C . Space Environment Branch ...10

AERO-ASTRODYNAMICS LABORATORY BIMONTIZLY PROGRESS REPORT

August and September 1967

TECHNICAL AND SCIENTIFIC STAFF ...... PROJECTS OPPICE ...... ADVANCED STUDIES OFFICE ...... A . Systems Analysis Section...... B . Flight Mechanics and Performance Analysis Group ...... C . Astrodynamics & Mission Analysis Group ...... AEROSPACE ENVIRONMENT DIVISION ...... A . Office of the Chief ...... 8 B . Atmospheric Research Facility ...... 9 C . Space Environment Branch ...... 10 D . Terrestrial Environment ranch...... 11 E . Environment Applications Branch ...... 14 ASTRODYNAMICS AND GLIIDANCE THEORY DIVISION ...... 18

I A . Scientific Advisory Office ...... 18 B . Optimization Theory Branch ...... 19 C . Guidance Theory Branch ...... 21 D . Astrodynamics Branch ...... 23 VI. AEROPHYSICS DIVISION ...... 25 A . Fluid Mechanics Research Office ...... 25 B . Mechanical Design Office ...... 26 C . Aerodynamics Design Office ...... 28 D . Experimental Analysis Branch ...... 33 r E . Thermal Environment Branch ...... 36 F . Unsteady Aerodynamics Branch ...... 37 VII. DYNAMICS AND FLIGHT MECHANICS DIVISION ...... 40 A . Multi-Projects ...... 40 B . Saturn V ...... 41 C . Saturn IB ...... 43 D . Saturn Apollo Application Program ...... 44 INDEX (Continued)

A. Special Projects Office ...... 51 B . Plight Mechanics Branch ...... 51 C . Tracking and Orbital Analysis Branch ...... 55 D . Flight Evaluation Branch ...... 60 AERO-ASTRODYNAMICS LABORATORY BIMONTHLY PROGRESS REPORT

August and September 1967

I. TECHNICAL AND SCIENTIFIC STAFF

1. The four earth orbital aeronomy experiments, including the passive sphere ensemble, the paddlewheelldif fuse spherelsmooth sphere combination, the densitometer and a mass spectrometer, have been investigated to determine their capabilities and limitations compared with similar concepts that have been proposed or performed. The results indicate that the Odyssey package constitutes a relatively ambitious program that can provide much useful atmospheric data in the poorly charted altitude range from about 140 km to 240 km. Thermal analyses have continued to investigate different surface finishes and materials and to include spin rate effects.

Informal discussions with Dr. Fellows and some members of the OSSA Planetary Atmospheres Committee were held in August 1967. This first contact and subsequent critical analysis by some members of the colmnittee established the recommendation that we complete our analysis and prepare for a formal presentation to the Planetary Atmospheres Committee. (Few)

2. Early Extravehicular Engineering Activities (EVEA)

The mid-term presentation on Contract NAS8-18128 "Extravehicular Engineering Activities (EVEA) Program Requirements with Emphasis on Early Experiments" was given by North American Aviation, Inc. , at MSFC on August 9, 1967. During the afternoon the MSFC-MSC contract management panel in a meeting chaired by the Contracting Officer's Representa- tive, Chester May, R-AS-VO, gave a critique of NAA's efforts to date. Again NAA was made aware of study deficiencies which had previously been called to their attention. NAA promised to comply with NASA contract directives. The difference between experimental EVEA and EVEA experiments was mutually defined.

Twenty technicallscientific experiments (requiring EVEA) proposed by North American Aviation, Inc., under Contract NAS8-18128 "Extravehicular Engineering Activities (EVEA) Program Requirements with Emphasis on Early Experiments," were reviewed the first of September. NAA intended to detail these proposed experiments to be performed in the 1971-1974 time frame for Phase I1 of the contract. Only six of the twenty experiments could be recommended to the COR as being feasible, timely, and furthering EVEA technology. In a subsequent meeting with NAA at Downey, California, the COR determined -- based on the experiment recommendations of his MSFC-MSC management panel -- that the contractor has still not fulfilled Phase I contract requirements even after earlier discussions with him on this deficiency. Resulting was a change in NAA technical key personnel and a five-month extension of the study contract at no further cost to the gwernment. Phase I1 will begin about Nwember 1967. (Nathan)

3. The Newtonian flow formalism developed in earlier work was applied to compute pressure distribution and polars for several surfaces. A paper was prepared for presentation at the forthcoming Fifth Technical Meeting of the Society of Engineering Science.

The current computer program for piecewise evaluation of covariance functions was studied in detail as part of the involvement in the crossed-beam undertaking.

A note is being written on the wind component measurable by crossed-beam experimentation.

11, PROJECTS OFFICE

1. Engine-Out and EDS Analyses

A number of MSFC-MSC Meetings have been held to resolve the Apollo/Saturn engine-out and vehicle breaklip problems. Work has been concentrated on AS-503 and AS-504. The following is a sumary of our present status:

The differences in the spacecraft loads on AS-503 and AS-504 are not as great as presented earlier. An error, a sign convention of a yaw acceleration term, in the spacecraft structural equations used in MSFCITBC simulations, was uncovered. In correcting this error, the spacecraft structural loads were reduced approximately 10 percent. With the corrected data, based on the limited cases examined, the AS-504 spacecraft has a 1.05 factor of safety during the maximum "q" region for one-engine-out. The spacecraft criterion is to maintain a 1.1 safety factor to assure the capability of always being able to abort from a malfunctioning vehicle. Since all indications are that the spacecraft is somewhat marginal for one-engine-out condition, MSC is planning spacecraft component testing. Test of the complete stacked spacecraft configuration may also be conducted. To support these tests and MSCINAA detail stress analyses, MSFC is generating additional data based on the latest spacecraft weights. The results of the launch vehicle tension structural tests of critical joints are showing that a greater launch vehicle capability exists than earlier calculated. This should also help resolve the problem of vehicle breakup at abort.

Plans are to have another joint MSFC/MSC Meeting when the state of the current activities (i.e., S/C structural testing, detail analyses by MSFCITBC and MSC/NAA, etc.) have progressed sufficiently to aid in formulating a firm course of action.

2. S-IB Aerodynamic Data

The Saturn IB, CSM configuration aerodynamic data have been revised to be compatible with the current configuration and recent wind tunnel stability tests. The basic effects are a forward shift in center of pressure (CPID)and a reduction in normal force coefficient, CN These data have been impacted within MSFC, and should not disturb %e Saturn IB program. These data will be used to verify design and to determine possible flight restrictions.

3. Saturn IB Minuteman

CCSD has completed a threermonth preliminary design effort of the Saturn IB Minuteman Configuration. Using the latest weights and design concept, i.e., MIM mounted parallel with the nozzles canted 7.5 degrees, the performance increase due to the Minuteman strap-on is - 6,000 to 6,500 pounds. Aero-Astrodynamics Laboratory areas requiring further study include vehicle control, Minuteman plume and shock impingement, Minuteman flutter, aerodynamic heating, S-IBIS-IVB separation and EDS crew safety. Plans are to conduct wind tunnel tests within the next six months. These include pylon flutter, base heating and launch deflector, detail loads, acoustics, and refined static stability and aerodynamic heating.

4. Flight Limits Subpanel (FLSP)

The Tenth Flight Limits Subpanel meeting was held at MSC on July 26, 1967. The minutes are documented in memorandum 67-E'M-13-319, dated August 29, 1967.

5. AAP Cluster

Work continued on the analyses of the first cluster mission in payload performance, orbital lifetime analysis, and tradeoff studies of orbital operations involving power, thermal, and attitude control conditions. The revisit mission AAP-3A between Mission A (AAP-1/ 2) and Mission B (AAP-314) was eliminated. Payload improvement studies completed for AAP-2 and UP-4 include investigation of jettisoning the SLA/NC during ascent as an integral unit by use of the LET jettison motor. Results show adequate clearance and a payload improvement of 2900 pounds. Payload improvement considerations for the AAP-1 and AAP-3 include the use of the CSM as a third stage to orbit andlor the use of a lightweight short SLA. Another approach is to reduce the required CSM weight by the elimina- tion of the SPS system. Various meetings have been held with MSC on performance improvements mainly through the Mission Requirements Panel and its Guidance, Performance and Dynamics Subpanel. Work is in progress for a meeting with Mr. Mathews on the AAP cluster in mid-October. Present lifetime studies show that the insertion altitude for the AAP-2 (OWS) can be reduced from the present baseline of 260 n.mi. This result stems from the improved prediction of the solar activity at launch that can be made as we get further into the solar cycle, the reduction of the solar activity as the launch schedule is adjusted to later flights, and the reorientation of the OWS solar array during storage to a position normal to the OWS centerline. The decision to reorient the OWS solar array during storage was based upon the desire to store the OWS vehicle in a local vertical (gravity gradient) orientation to save propellant of the OWS Auxiliary Attitude Control System (AACS).

111. ADVANCED STUDIES OFFICE

A. Systems Analysis Section

The final review of the DAC study, Contract NAS8-21051 "Use of Large Solid Motors in ~oosterApplications:' was conducted at MSFC on August 30, 1967. One major task, a detailed comparison of TVC systems for application to the 260" SRMIS-IVB launch vehicle studied previously, resulted in recommendation of a movable nozzle TVC over a liquid injection system. The results of the other major task in the study, the preliminary design and evaluation of a 156" SRM/S-IVB launch vehicle, indicated that a cluster of four 156" SRM's with approximately 1.12 million lbs of propellant each was the most desirable configuration for a boost stage. This design seems feasible, is cost effective, and yields a payload of 108,300 into a 105 n.mi. orbit. No major design problems were encountered. DAC performance on this study was quite satisfactory, and sufficient technical depth was achieved to make the results meaningful. The final report has been reviewed, and comments have been transmitted to DAC through the COR. B. Flight Mechanics and Performance Analysis Group, R-AERO-XF

1. In support of ASO, the performance of a nuclear stage as the third stage of a Saturn V has been investigated, and the preliminary results have been documented. Additional effort is anticipated for proposed extensions.

2. Preliminary performance analysis has been generated on the 660K vehicle (Saturn V with 156" liquid pods) as requested by R-P&VE-A. This information is to be used in the long range planning activity in ASO.

3. Considerable interest is being shown in the Titan family of launch vehicles. This office is gathering available data on this system and will soon initiate studies to evaluate its performance capability.

4. A memorandum, R-AERO-X-67-82, "Performance and Trajectory Data for the Saturn SA-217 Vehicle Improvement Studies," has been distributed.

5. The OPGUIDE trajectory computer program, furnished by IBM, is being exercised on the CDC-3200. This trajectory tool should increase our quick response capability.

6. The Booster Optimization Program is being modified to handle intermediate orbits other than circular. In the past this program would simulate only LOR-type mission profiles.

7. This group is generating preliminary performance analysis in support of the AS0 in-house Low Cost Launch Vehicle Study and Saturn Utilization Study. These in-house studies are expected to continue for about 4 to 6 months.

C. As trodynamics & Mission Analysis Group

1. Low Thrust Computer Program

A low thrust trajectory shaping program which calculate optimum heliocentric transfer arcs has been obtained from Princeton University. The program has two basic modes of operations: (1) Path optimization between two terminal points with all vehicle parameters fixed. The optimization is carried out by the calculus-of-variations technique. (2) Spacecraft optimization in which the propulsion parameters are allowed to vary and the program determines the best combination of specific impulse and thrust level. The quantity maximized in this mode is the payload defined as the initial mass of the spacecraft less the masses of fuel, fuel tanks, structure and power plant. The program has the capability of optimizing the magnitude and direction of the departure hyperbolic excess velocity. The mass flow rate may be a constant as in a nuclear-electric system or may be varied as a function of distance from the sun as in a solar-electric system. 2. Voyager Missions

R-AERO-X results of the MSFC study of possible alterna- tives to the 1973 Voyager mission are summarized in the datafax to OSSA from Dave Newby. There has been some additional parametric data generated to determine optimum AV to be imported by the transtage and the spacecraft to perform the earth escape and Mars capture maneuver. Effort will now be renewed on the in-house study "Application of the Voyager Spacecraft to Venus and Jupiter Missions" being conducted by personnel of the collocated elements and Advanced Sys tens Off ice.

3. Planetary Parking Orbit Analysis

The mission requirement for the capture and escape maneuver associated with planetary parking orbit can be evaluated with a computer program developed and checked out by Northrop. At present, the program optimizes the composite capture and escape maneuver requirement for planar conditions. The program is being extended to handle the general 3-dimensional problem.

4. Missions for Exploration of the Outer Planets

A mission planning handbook for exploration of the outer planets -- Saturn, Uranus, Neptune, and Pluto -- using .Jupiter's gravity assist, has been completed by Lockheed's mission support personnel. The handbook should be available for distribution in two or three weeks.

5. Out-of-the Ecliptic-Plane Missions

Northrop has been assigned a task to generate attractive mission profile and associated parameters for out-of-ecliptic plane missions. Flight duration from 1 to 365 days and launch opportunity from earth during any month of the year will be considered.

6. Manned Planetary Flyby Mission Based on SaturnfApollo System

NASA Headquarter's has released the final reports of the "Nanned Planetary Flyby Missions Based on Saturn/Apollo System." The reports are now being distributed.

7. Alternative Mission Modes Study

A final briefing of the results from the "Alternative Mis- sion Mode Study was given by TRW personnel on September 13, 1967. The object of this study is to make more attractive, through trajectory shaping and phasing, the following: (a) initial weight required in earth orbit,

(b) miss ion duration,

(d) earth reentry velocity,

(e) mission window sensitivity,

(f) sensitivity of mission requirement from one opportunity to the next opportunity,

(g) operation flexibility.

Of all the missYon profiles considered, the Venus swingby mode continues to look the most attractive. However, the Mars conjunction class mission profile offers about the same weight in earth orbit, but has a longer mission duration (about 350 days).

The study results are documented in two volumes: Volume I contains the summary of the study results, Volume I1 the detail technical results. The two volumes will be distributed in about a month. IV. AEROSPACE ENVIRONMENT DIVISION

A. Office of the Chief

Mr. Otha H. Vaughan, Jr. has continued to receive, identify, and assemble a catalogue of the photographic data from the Orbiter Program. This photography provides a useful reference for studies relating to the Voyager Program and other types of missions.

Mr. Vaughan has maintained contact with members of University of Arizona's Lunar and Planetary Laboratory, Jet Propulsion Laboratory, Manned Space Center, United States Geological Survey, Center of Astro- geology, Bellcoma, NASA Headquarters, and Langley Research Center who have been analyzing the Orbiter data in support of the Apollo Program.

Don Weidner and 0. H. Vaughan have co-authored a report, "Mar's Environment: An Interpretation of the Atmosphere and Surface." This report is almost complete and should be documented during October.

A report on the environment of Mercury being.prepared by Mr. Vaughan should be completed by October 25, 1967. This report sum- marizes the atmosphere and surface cohditions expected for Mercury.

Don Weidner and 0. H. Vaughan are continuing with Northrop support to develop a thermal environment prediction of the surface temperature and its effects on the atmosphere of Mars. Recent computer runs have indicated that the surface temperature program can predict the temperature; however, we are still trying to correlate with actually measured data. Later we hope to predict atmospheric conditions for Mars.

Mr. 0. H. Vaughan has recently completed a proposed lunar exploration mission plan, which is documented in TM X-53655, "A Pro- posed Hypothetical Lunar Exploration Mission in the Flamsteed Crater Region of the Moon."

Some of the Orbiter I and I1 photographs were analyzed to help establish and update design criteria for lunar surface roving vehicles. This analysis was then combined with other data (personal discussions with members of JPL, USGS, MSC, and Bellcomm) and a report, T&l X-53661, "Lunar Env jronment: Design Criteria Models for Use in Lunar Mobility Surface Mobility Studies," has been prepared. Mr. 0. H. Vaughan is still a member of the Voyager Science Panel here at MSFC, and will concinue to work with them when requested. B. Atmospheric Research Facility

1. Eighty-four rawinsonde flights were made during this reporting period in support of acoustic studies, static tests, Army surface- to-surface missile launch, as well as for the continuing compilation of a station history. There were 33 flights in support of acoustic studies and static test: 18 flights for the S-IC firings on August 1 and August 3, and 15 flights for four F-1 tests. Six flights were made in support of a Boeing contract requiring dual radiosondes per flight with dual tracking. The Army Test Range was supported with three flights in their surface-to-surface missile launch on August 24. The station history program required 42 releases.

A workshop, conducted by the Atmospheric Research Facility personnel on the Bendix Model 3002 lightweight transpondersonde, was attended by personnel from the several test ranges and research laboratories throughout the U. S. The workshop consisted of releases of the Model 3002 and discussions of the problems encountered and possible solutions. The major problem was defined as noise in the ranging circuit of the radionsonde itself.

2. The CPS-9 Weather Radar+is being installed by GEETA. The azimuth unit and reflector were located and are now on site. The tower is complete except for placement of the azimuth unit and warning lights on the tower. The radar installation crew are now installing the electronics.

3. The cross-beam project equipment was sent to Colorado during this period. The sensors and mounting booms were removed from the Army's tower, and were packed and shipped to Colorado. These booms and sensors were installed on the Colorado tower, and Colorado personnel trained for operations of the meteorological equipment.

4. The Ionospheric Sounding Station was checked out and mounted in an equipment van. The system, which worked properly under dumy loads, is ready to be moved to the antenna field location and begin the operational checkout. The 600 ohm Resistor Model in the antenna system has been shipped and should be on site the first week in October.

5. Data acquisition is continuing for the tower interference study and wind profile mapping program from the 150-meter meteorological tower at Kennedy Space Center.

6. Meteorological satellites were tracked and the position and movements of hurricanes were plotted. The hurricane position and movement were relayed to Industrial Operations, MSFC. This information is continuously relayed to responsible parties until the storm is no longer a definite threat to KSC and/or MTF. Tests began on four Climet Wind Speed and Wind Direction Sensors on the Dynamic Wind Stand. These data are to be used in an Anemometer Comparison Study. More tests are scheduled on other types of anemometers as wind conditions permit.

C. Space Environment Branch

1. Ionospheric Study Program

The transmitting site at Pulaski, Tennessee, has been put on operational status, and it is expected that the Limrock School site will become operational within a matter of days.

Initial data are being taken for further study of acoustic gravity wave propagations from high energy ground-based acoustic sources Preliminary reports on this study will be given this month at meetings in Lucerne, Switzerland, St. Gallen, Switzerland, and Ankara, Turkey.

Papers have been accepted for presentation at the Fall Meet- ing of the Acoustical Society of America which will be held in Miami Beach, Florida,on November 14-17, 1967. A paper will be presented at the URSI meeting to be held in Ann Arbpr, Michigan, during October on temperature and electron density measurements taken at Cape Kennedy on January 24 of this year.

Solar Flare Probability Model:. A preliminary report has been submitted by Northrop on a solar flare probability mode. A recent meeting on the statistical techniques being used in this program revealed that, whereas the results are interesting and with more data may provide a worthwhile prediction model, the current trend seems to indicate that a different line should be pursued.

2. Participation in MSFC Research Achievements Review No. 10

Personnel from the Space Environment Branch participated in the Aerospace Environment MSFC Research Achievements Review No. 10 in the Morris Auditorium, Bldg. 4200, Thursday, September 28, 1967. The following is a list of these people and the title of the papers they presented:

Robert E. Smith, Chief, Space Environment Branch, "Diurnal Variation of Density and Temperature in the Upper Atmosphere."

William T. Roberts, ,Space Environment Branch, "Ionospheric Disturbance and Diurnal Variation of Electron Density and Temperature."

George S. West, Jr., Space Environment Branch, "Martian Atmospheric Variability ." D. Terrestrial Environment Branch

1. The explicit purpose of the NASA Administrator Headquarters Policy Directive NPD 8070.1 frm the Deputy Administrator, entitled, "Policy Concerning the NASA Space Vehicle Design Criteria Program," is to establish the policy and objective and to assign responsibilities governing the NASA Space Vehicle Design Criteria Program. Pertinent to this Directive, the Terrestrial Environment Branch has agreed to prepare a monograph to define the vertical structure of the thermo- dynamic quantities of the earth's atmospheres. This task is referred to as "Inflight Atmospheres." Preparatory work for this task is reported under item 2 below. Specific work on this task will begin next month.

Two important definitions are given in the Policy Directive cited in the previous paragraph:

a. "Space Vehicle Design Criteria provide environmental and design factors that are to be taken into account in the des,ign of space vehicles in order to enhance space vehicle mission success. They do not, however, specify the capability of a specific vehicle to meet specific mission requirements."

b. "The term 'space vehicle' includes both launch vehicles and spacecraft ."

These definitions were prepared for the purpose of the Directive, and should not be used out of context.

However, advance planning has led to several related tasks oriented to meet a cmon objective; viz., to determine the capability of specific space vehicles to meet specific mission objectives in terms of atmospheric launch constraints. This is a major work area for the Terrestrial Environment Branch. The following sections illustrate progress in meeting this objective.

2. Reference Atmospheres

The Supplemental Atmospheres are model atmospheres for different latitudes and are supplementary to the 1962 U.S. Standard Atmosphere. This task is to establish convenient and efficient corn- puter subroutines for the supplemental atmospheres to be used in advanced re-entry heating studies, and to form the bases for cornparing further investigations leading to the development of the NASA Inflight Atmospheres Monograph. 3. Research Achievements Review

Progress relating to problems concerning atmospheric constraints to Saturn Vehicle Launches and Mission Analysis was presented at the Tenth Research Achievements Review on September 28, 1967. A paper concerning these subjects will soon be published in comprehensive form.

a. Empirical Statistics

(1) Hourly Peak Wind Speed Sample for Cape Kennedy, Florida.

Hourly Peak Wind Speed Statistics compared to Saturn V design winds.

(2) Maximum Winds in 10-15 km layer over Cape Kennedy, Florida.

(a) Analysis-of-runs procedure for determining conditional probabilities of winds aloft.

(b) Persistence- studies of winds aloft.

(3) Thunderstorm Statistics

(a) Frequency of occurrence at Cape Kennedy.

(b) Peak winds associated with thunderstorms.

b. Theoretical Statistics

Extreme Value Theory:

(1) Fisher-Tippett Distributions

(2) Calculated Risk Concept

(a) Daily peak wind speed statistics for Cape Kennedy.

(b) Hourly peak wind speed statistics for Cape Kennedy: (1) all hours, (2) speci- f ied starting hours.

To aid in determining the probability of an Apollo LEV impacting on land, all necessary wind observations and statistics plus three possible methods of using the data were given to MSC. Also, an analysis of low level (0 - 2 km) easterly (060° - 120') winds by month and time of day was presented.

5. Contractor

a. Lockheed Support Contract

For mission analysis purposes, a method of computing atmospheric launch constraint probabilities has been developed. Five atmospheric variables -- ground winds, winds aloft, cloud ceiling, visibility, and weather -- are considered as constraints. Capability at present includes probability of "no launch" at T = 0, and conditional probability of "no launch" for the next 24 hours.

b. NWRC Contract - Government Order 76789

Several Cape Kennedy atmospheric data samples are being developed and continuously updated at the National Weather Records Center. Those completed include hurricanes and peak hourly wind speeds. Still under development are thunderstorm, cloud and visibility, and winds aloft samples.

c. University of Georgia

Current efforts are being devoted to mathematical launch probability models for the Saturn ViVoyager relative to launch constraints from atmospheric causes. The principal atmospheric launch constraints are known to be persistent with respect to time and space, and they may be correlated with respect to each other. Consequently, classical statistical analysis which requires randomness for the variables is not valid. Bayesian methods and Markov processes are being investigated for solving "error propagation" problems to determine composite launch probabilities. The resulting atmospheric launch probability model is a prerequisite for mission analysis, design studie and total sys terns capability. E . Environment Applications Branch

1. R-AERO-Y/SRI Contract

Work is progressing satisfactorily on contract MSFClNAS8- 21148 entitled, "Relationship Between Micro-, Meso-, and Synoptic-Scale Atmospheric Motions," with the Stanford Research Institute, Menlo Park, California. The principal investigator (Mr. Roy Eulich) indicated recently that SRI is preparing a plan to analyze the FPS-16 radarf~imsphere wind profile data, made available to SRI by R-AERO-Y, so that necessary answers can be obtained to fulfill the scope of work. Particular emphasis is being placed on techniques of forecasting short-term detailed wind velocity variations in the upper atmosphere. Mr. Kaufman (COR on this contract) has requested Mr. Eulich to visit MSFC/R-AERO-Y about December 1, 1967, to familiarize all responsible R-AERO-Y personnel on work being done on this study.

2. Wind Monitorship Activities

The wind monitorship room at HOSC is equipped for operational use. The real time contingency FPS-16 radarl~imspheredata reduction program(~)for CDDT and preflight,data analyses has been checked out. The only difficulty is that, during the time the vehicle flight simulation is being run coincidently with the wind pfofile data reduction process, a few wind velocity data points are deleted. The real time anemometer data Irom LC39A are now being received and appear to be representative. Further checks are to be made to compare these LC39AfHOSC anemometer data to verify accuracy, etc.

3. Gust Factor Analysis

Gust factor analysis from wind data measured from February through August 1967 at IiASA's 150-meter Meteorological Tower Facility, KSC, Florida, is continuing. The analysis is being made to relate gust factor to height, mean wind speed, and time periods used to define the mean wind speed. Results will be presented in memorandum form in the near future.

4. NWRC Meteorological Tower Data Reduction

A magnetic tape was received from the National Weather Records Center, Asheville, North Carolina, of data from NASA's 150-meter Yeteorological Tower Facility, KSC, Florida, for December 1965 through December 1966. MSFC'S Computation Laboratory is processing these data through the numerous programs for R-AERO-YE studies. 5. Wallops Island FPS-16 ~adarl~imsphereProgram

The FPS-16 radarlJimsphere wind profile data acquisition program is being initiated at Wallops Island, Virginia. Once the magnetic tape and data format programs are firmly established, the Wallops Island personnel responsible for this task will begin making two sequential Jimsphere balloon releases per month (i.e., 6-8 balloons released per sequence which covers a period of 9-12 hours, respectively). Mr. Susko of R-AERO-YE is coordinating this effort with the Wallops Island personnel.

6. MSFCIUSAF Clear Air Turbulence Program

Mr. Charles K. Hill, R-AERO-YE, participated with U. S. Air Force personnel from Wright Patterson Air Force Base, Ohio, in a clear- air turbulence measurement program at Cape Kennedy on September 12-15, 1967. FPS-16 radar/Jimsphere balloon wind data obtained in series of six flights daily at intervals of 1 112 hours were analyzed to identif) potential regions of turbulence in the 15-18 km layer. An Air Force instrumented U-2 aircraft was vectored into the layers as specified by Mr. 1 Aircraft instrumentation problems and poor local flying conditions resulted in program delays; however, on September 15, the U-2 successfully flew into and investigated several regions where the generation of turbulence was considered possible. Although one layer was found where light turbulence was. experienced, severe clear-air turbulence was not detected because of the upper attitude wind conditions during this period.

Cooperation from the U. S. Air Force personnel and the KSC data measurement and processing personnel was excellent. MSFC's brief participation in this program was considered favorable, and should additional research in this area become desirable, further work on this can be conducted.

7. Analysis of Wind Field Conditions which Adversely Affect Vehicle Operations

The final evaluation of five proposals submitted in response to RIQ DCN 1-8-75-00033 on "Analysis of Wind Field Conditions which Adversely Affect Vehicle Operations," has been completed. As a result of this technical evaluation, the University of St. Thomas in Houston, Texas, has been determined to be the best qualified to perform the desired tasks. The primary emphasis in this work will be in developing a thunderstorm model applicable to the KSC environment which will enable a better understanding of intensity, movement, and associated surface winds in these storms in the vicinity of the Saturn launch complexes. 8. 1600 Ft. Tower Wind Data from Norman, Oklahoma

Hourly digitized wind data for the period May 18 through July 25, 1966, have been received for the 1600-foot tower near Oklahoma City. The National Severe Storm Laboratory in Norman, Oklahoma, is measuring and reducing these data for R-AERO-YE, completing the reduction of the tower data through January 1967, and is now checking and correcting errors. It is expected that a full year of these data will be available soon, along with some selected periods of fast-run data during which thunderstorms or frontal conditions existed.

9. MSFC Anemometer Comparison Tests

A new series of anemometer comparison tests has been initiated. In this series, it is expected that all presently available anemometers will be tested. These anemometers will be of the cup, propeller, hot-wire, and sonic types. It is hoped that from many of the anemometers tested it will be possible to get the vertical component of wind velocity, in addition to higher resolution horizontal speed and direction data. The results of these tests will be made available in internal memoranda.

10. MSFC/GCA Temperature Sensor Contract

Mr. Dennis W. Camp visited the GCA Corporation, Bedford, Nassacl~usetts, on September 7-8, 1967, to discuss the Jimsphere temperature sensor contract (NAS8-20588) and to witness demonstration flights of the sensor. One of the two demonstration flights was not completely successful due, it was believed, to a bad connection between the electronic package and the balloon-borne antenna. The other flight appeared to be successful. As a result of these two flights, it was determined that acceptance testing of the temperature sensor system is scheduled for the second week of October at Cape Kennedy, Florida.

11. Turbulence Characteristics at KSC

The data acquisition program at NASA's 150-meter meteorological tower at KSC is continuing. These data constitute both routine measurements of wind velocity, temperature, and other atmospheric variables, as well as special measurements of the wind speed and direction for the study of turbulence characteristics at KSC. These data are being analyzed via two approaches: spectral techniques and discrete gust techniques. The Pennsylvania State University, under contract NAS8-21140, is examining the spectral nature of these data, while Cornell Aeronautical Laboratory, Inc., under contract NAS8-21178, is examining the discrete gust properties of these data. In addition, R-AERO-YE is performing studies in both of the above mentioned areas. a. Pennsylvania State University (NAS8-21140)

During this period, it has been requested that the termination date of contract NAS8-21140 be changed from June 2, 1968, to September 13, 1968. The change is needed because MSFC Computation Laboratory will perform a majority of the computational effort. Thus, funds that would have been used by PSU for computations are now available for performing a more detailed and extended scope of work. The COR and the principal investigator have agreed on this extension. The current spectral computer program being used to reduce the 150- meter meteorological tower data on this contract has yielded physically impossible results, namely, negative spectral estimates and coherence values greater than one. The difficulties have been attributed to improper detrending procedures in the Tukey-Fourier transform computer deck. This program, which is now being modified, will be operational by the second week of October.

b. Cornell Aeronautical Laboratory, Inc. (NAS8-21178)

During the first part of this reporting period, Dr. G. E. McVehil and Mr. Roland Pilie of CAI, met with Dr. J. R. Scoggins and Mr. G. H. Fichtl of R-&RO-Y and Mr. T. G. Reed of R-AERO-AU to discuss ground wind inputs needed for Saturn V vehicle response studies. This was the initial meeting between CAL representatives and MSFC personnel on this contract. Since Dr. Scoggins, the original COR on this contract, is no longer with MSFC, Mr. G. H. Fichtl is now the current COR. Several wind inputs for vehicle response studies were discussed. It was concluded that information is needed with regard to (1) the probability of a gust striking a launch vehicle with a gust factor of 1.4 (present MSFC design value) and being completely correlated over 75 percent of the vehicle for periods of 3 seconds and 20 seconds after the onset of the gust with variations in wind direction being less than t15; (2) the reliability of the gust factor employed by MSFC; and (3) the spectral nature of the lateral and longitudinal components of turbulence in the frequency band interval of .2 to 3 cps. Six one-hour cases of turbulence from the NASA 150-meter meteorological tower at KSC were sent to CAL for analysis during this period. These are fast wind cases (wind speed greater than 10 m sec-I). CAL will analyze these data with regard to wind statistics for varying record length (5 minutes to 1 hour) and probability distributions of wind velocity. In addition, CAL is studying these basic areas stated above. V. ASTRODYNAMICS AND GUIDANCE THEORY DIVISION

A. Scientific Advisory Office

1. The preliminary hand-computing of the various influences on the lifetime of artificial Mars satellites and the survey of the pertinent literature have been continued.

Two special aims have been pursued:

(a) To restrict the usual concept of "lifetime" to "lifetime useful for a given mission" in order to monitor a specific area of the surface for an optimal time-interval.

(b) To investigate the feasibility of using perturbations by Jupitep at times of close approach of Mars and Jupiter for a desired kick at periapsis, or also to orient the orbit of the satellite in such a way that undesired perturbations could be avoided.

It is planned to complete the hand-computing soon, and to adapt the problem for machine computations in order to obtain precise results for this multi-parameter study. (Festa)

2. A paper entitled, "e-~ixeB Stability," has been completed and submitted to the Bulletin of the Canadian Mathematical Society for publication.

A first draft of the paper, "C&nonical Realizations," has been completed. The paper has been accepted for publication at the Asilomar Conference in Circuits and Systems in November.

The paper, "Equivalence of Certain Stability Properties," has been accepted for publication in the SIAM Review in January.

A paper based on results in "Equivalence of Certain Stability Properties," has been completed and submitted to the American Mathematical Society for presentation at the 74th Annual Meeting in San Francisco in January.

The paper "On A Finite Time Stability Property of Krasovskipf has been completed and submitted for publication in the SIAM Review.

Current effort is concentrated upon developing a practical stability concept which includes, as special cases, the classical stability of Liapunov as well as practical stability concepts of Krasovskii and Halaney. (Gunderson) B. Optimization Theory Branch

1. Trajectory Optimization

a. Investigations on the transformation of the Hamiltonian which describes the optimal trajectory of a rocket in a purely Keplerian gravitational field have continued. Automation of canonical transformations in the optimization problem is being studied. Once such a program is in existence, it should be relatively easy to examine new transformations. This procedure should ultimately lead to the incorporation of the "angular momentum" integral into the optimal trajectory equations.

b. An analytic solution for the motion of a body under the influence of a uniform planar force field and a Keplerian field has been derived and numerically verified. A report on the subject has been submitted for review.

c. Because of the large variety of numerical trajectory optimization techniques currently being used by various organizations, it would be desirable to establish some basis of comparison of the virtues and limitations of the various techniques to determine the advantages and disadvantages of each for various classes of problems. A new project involving comparison of numerical optimization techniques has been initiated. This comparison is not, as yet, well defined with respect to the parameters to be compared. Various quantities such as radius of convergence, running time, ease of programming, etc., must be examined.

d. Northrop Schedule Order /I32

Objective: To determine the applicability of functional analysis to the optimization of aerospace vehicle trajectories.

The first formal publication of this study has been received. This report entitled, "Conversion of Boundary-Value Problems into Problems of Numerical Integration," was published as TR-792-7-231, ~ortronics/~untsville.Discussions with the contractor (during this reporting period) were conducted to map future research activities.

c. North American Aviation (NAS8-21007)

Objective: To develop methods of finite thrust optimal transfer.

During this reporting period, work continued on the numerical solution to the three-dimensional orbit transfer problem. Difficulties have arisen due to a conversion of computer facilities at the contractor's plant. As a consequence, the contractor may ask for a no-cost extension to the contract. The section of the contract dealing with impulsive lunar transfer trajectories is now operating satisfactorily.

2. Flight Control

a. Honeywell (NAS8-21171)

Objective: To improve the performance of the load relief control system for the Saturn VfVoyager designed by Honeywell under NAS8-11206.

Activities during the first two months of the contract have centered in the following areas: (1) the preparation of the 45- foot data for analysis on the digital and analog programs; (2) the planning of the details of the study to insure maximum utilization of the earlier study, and to reflect current requirements; and (3) verification of the computer programs to be used in the analysis.

Nominal time responses of the 45-foot payload vehicle will be determined and compared with the 54-foot results. The system will be modified to reduce any.sensitivity to vehicle parameter varia- t ions.

b. Boeing (NAS8-21070)

Objective: To study the application of the Saturn V/ Voyager load relief system and other load re'lief systems to the Saturn/ Apollo.

The time-varying hybrid simulation of the rigid vehicle with various candidate control schemes is complete. A selection of the system(s) to be analyzed further, considering flexible body behavior and compensation network requirements, is expected to be made soon. Reduc- tions of up to 40 percent in peak bending moment compared with attitude control have been achieved with linear feedback. This maximum reduction was achieved with a relatively complex system employing angular platform acceleration (as is used in the Acceleration Vector Attitude Control systems), rotational, and body-mounted linear acceleration feedback. It has not yet been determined whether or not this system should be considered further (because of its complexity).

c. Honeywell (NAS8-21063)

Objective: To investigate further the application ot the statistical optimization technique developed under NAS8-11206. Data preparation is essentially complete, modification oL thc optimization program to include flexible body and slosh effects for the present study is nearing completion, and the distributed wind loads model or gust penetration model to be used in this study has been derived. (Distributed loads representations are necessary to keep bending moment rates used in the program finite for the current wind model. )

d. Systems Technology, Inc. (NAS8-11419)

Objective: To determine the limitations of conven- tional control systems for vehicles exhibiting a large amount of inter- model coupling.

Copies of the final report have been received. The report is to be distributed with a cover memo outlining the results of the study. As reported previously, successful control for this class of vehicles was achieved by use of a lagged normal accelerometer for flexible body and slosh stabilization.

C. Guidance Theory Branch

1. Support Contract Studies

a. General Inteplanetqry Studies

The results of a study to determine the advantages and disadvantages of using the spacecraft as a "kick" stage have been documented.

Work was completed on a guidance analysis to determine the effects of the large drift and drift rates that occur as a result of using the load-relief control system during high winds. The results were given to R-AERO-GO for use in their studies of the load-relief control system.

A study has been initiated to determine the effects of Saturn V hardware errors on the injection accuracy of an interplanetary trajectory. This study should produce a statistical description of the injection errors.

b. Quasi-Optimal Guidance Study

The Quasi-Optimal Guidance Scheme (QUOTA) has been compared to COV and the flight times for various cutoff conditions were the same. A perturbation study indicates that QUOTA is capable of correcting for system disturbances in a near-optimum way. QUOTA'S flexibility was demonstrated by its capability to fly a continuous thrust orbital transfer between an inner circular orbit and an outer coplanar circular orbit. So far, we have not been able to make the IGM fly this type of mission.

c. Optimal Guidance Study

Newton's method with integrated error partials is being applied to missions with intermediate coasting arcs. The program is being checked out. When this is completed, effort will be directed toward increasing the speed of the program so that it can be used as a guidance scheme.

2. Contracts

a. Vanderbilt University

The final report has been received.

b. Lockheed-Voyager Terminal Guidance Analysis

A computer program has been modified and an iteration scheme has been incorporated to isolate automatically the total fuel expenditure and weight de1ive;ed for a given guidance technique and starting point in Mars orbit. Runs are being made to determine the available perigee rotation capability as functions of particular approach hyperbolas and guidance scheme employed. c. Lockheed - Rendezvous Guidance

Two reports entitled, "Simplified Laws for the Two- Finite Burns Minimum Fuel Planar Rendezvous Problem," and "Closed-Loop Terminal Guidance for the Two-Finite-Burns Minimum Fuel Rendezvous Problem," have been published. Computer simulation of the first-burn guidance equations is extremely rapid for a given fuel allotment, and a simple method is being developed to minimize this allotment. Simula- tion of complete two-burn rendezvous missions including closed loop terminal guidance is being undertaken.

d. General Precision

Although the contract expired on September 7, 1967, the contractor is still working to complete the study and write the final report. The contractor is comparing the quasi-optimum steering laws with IM. A family of 500-second-duration optimal trajectories is being used for the comparison on General Precision's generalized nonlinear control system simulation program. 3. In-House Studies

a. Voyager Studies

A study to determine the possible gains in launch opportunity via plane change maneuver with the S-IVB has continued. The performance has been determined by impulsive approximations; however, integrated trajectories are being run to verify that IGM can handle this "dog-leg" maneuver. The integrated trajectories will also be used to verify the performance calculations.

Alternate mission modes have been proposed for the Voyager program. During this reporting period, two of these modes were investigated and the results presented.to Mr. Newby. There were (1) the Saturn 1~1Centaurwith a small spacecraft, and (2) the Saturn IB with a large spacecraft that could be used to provide the out of orbit burn to injection and the braking maneuver at Mars. Neither of these modes appeared very attractive from a payload standpoint.

b. In support of the optimal guidance study, closed form solutions for the error partials across a coast arc have been formulated. The equations are being worked out in a.form suitable for programming as a subroutine which can be incorporated into the optimal guidance program.

c. An IBM source deck for computing three-dimensional, nonatmospheric, minimum time trajectories has been acquired. The deck, called "OPGUIDE 1," is being converted for use on the CDC-3200 computer.

D. As trodynamics Branch

1. Interplanetary Transit Studies (In-House)

a. Work has been resumed on the n-body interplanetary program. The free flight portion of the deck, along with the input and output routines and the coordinate transformations, has been essentially completed. Work is now being concentrated on the inclusion of an isolation routine, as well as other deck improvements such as optimum change of phase points, generation of initial ephemeris data, and the appro- priate selection of sets of independent and dependent variables for use with the isolation routine.

b. Studies to produce tradeoffs which can be made with respect to orbit size, arrival energy and orbit insertion AV requirements continue. This should provide an easy method for studying trade- of fs between -ientif ic and engineering cons traints . c. A routine has been incorporated into the Marshall Inter- planetary Conic Program which will compute a daily launch window and the parameters of the near-earth launch hyperbola as functions of the direction of the launch asymptote, the performance of the launch vehicle and the launch azimuth. The launch window is defined by the time of day of launch, coast time in orbit, and the coordinates of the initial and terminal points of the various burns.

With this additional capability, the Marshall Inter- planetary Conic Program can be used as a suitable replacement for the JPL Conic Program.

2. Interplanetary Transit Studies (Support Contractor)

a. A computer program developed by LMSC/HRECfor determining the occultation characteristics of various Mars satellite orbits is still being checked out. Final checkout has been delayed by problems discovered in relating the interplanetary phase to the orbital phase. Orbital definition is very much dependent on the interplanetary arrival conditions at Mars, and the proper usage of the developed program requires the proper relating of these two phases. Previous studies have considered the two phases as separate problems.

b. Work has been completed on the analysis of broken-plane transfers to determine the feasibility of modifying some of the operational single-plane computer programs to consider the broken-plane cases when near 180-degree heliocentric transfers are encountered.

c. Documentation of the various flight parameters for Type I1 Earth-Mars trajectories in the 1973-1979 time period and the constant energy, flight parameter plots for energies up to 40 km2/sec2 during the 1973-1979 time period has been completed.

d. Two alternate Voyager payloads were studied under the assumption that the lander capsule would be dropped from the Voyager mission. The first alternative studied was to convert the capsule weight to additional spacecraft propellant. The second was to keep the same propellant loading and to reduce the payload. An analysis of the results of both a1ternatives was presented.

e. Studies have been initiated on the mathematical model- ing of relativistic effects, potential functions, n-body terms, and non- gravitational forces which need to be included in the construction of an idealized interplanetary computer program. These studies also include investigations of targeting functions and the convergent proper ties of isolation routines. Initial work has been concentrated on a review of previous work in the area of interplanetary programs and the adequacy of the mathematical models within these programs. After this review, work will be centered on the least understood forces, and attempts will be made to improve the models. Work on an isolation routine is intended to provide a workable, all-purpose routine for the wide variety of interplanetary problems encountered.

3. United Aircraft Corporation (NAS8-21091)

A format for reviewing articles and papers has been adopted. Each of the approximately 300 entries will be described by four cate- gories : (1) classif ication description, in which the problem treated is summarized, (2) applications, (3) approach used in solution, and (4) results. Entries will be reviewed and described by topic with an overall classification being made for each specific subject area only after all papers in that area have been reviewed. Topics already reviewed and classified include deorbit and orbit rendezvous. Transfer between coaxial ellipses has been chosen as the next subject for intensive study.

A source of translated Russian papers on impulsive transfer, overlooked in the initial literature search, has been discovered in 11 Cosmic Research." Thus, several pertinent Russian papers have now been added to the bibliography.

VI. AEROPHYSICS DIVISION

A. Fluid Mechanics Research Office

1. Aerodynamic Crossed-Beam Programs

Schlieren still photographs and movies have been completed in the TAJF for the S-I1 cluster base model plume and jet interaction regions. Also completed is a test program measuring the total pressure in the cluster plume and shear layers. The combined results of the above tests give valuable qualitative information of supersonic sound sources in clustered jets. The cluster model has been instrumented £01 making mean and fluctuating base pressure measurements, and the test phase in TAJF is underway.

2. Nozzle Contour Computer Program for IBM-1130

A nozzle contour program written for the cluster nozzle program has been completed and is now operational. The program was written for determination of the internal configuration of the model for the F-1 simulation test to be run in the 14-inch special test section. For detailed discussion see R-AERO-A-67-17. 3. Crossed-Beam Field Tests

A new mobile field laboratory and two special remote detection systems with extremely low noise levels have been moved to the Army firing range at Patton Road. These instruments were designed to verify crossed-beam wind measurements under optimal condition, i.e. , under a clear sky. Field tests at the 400-foot high meteorological tower were performed by crossing the beams in front of an anemometer at the top of the tower. The results indicate the following: (a) Atmospheric beam modulations which can be detected under clear skies are well above the instrument noise. (b) The cross correlation of two beams indicates that the rms signals which are common to both beams are approximately 10 times smaller than the integrated rms beam modulation. (c) The temporal cross correlation curves always show several peaks. It appears that one can locate one peak at a time lag which corresponds to the anemometer wind reading. (d) The extension of field tests to partially clouded skies will require the addition of digital recorder, electronic and optical filters or infrared detectors. Field tests with the present sys tem will continue as scheduled at the meteorological test site of Colorado State University.

B. Mechanical Design Office

1. Viscous Cross-Flow Pressure Model

A 4-inch diameter pressure model, an ogive-cylinder with 689 pressure orifices, for test in the LTV High Speed Wind Tunnel is being designed. The design will allow replacement of the ogive nose with other selected shapes.

2. Centaur Stage for Aeroelastic Model of Saturn IB

Request has been made for the design and fabrication of an aeroelastic Centaur stage for the existing Saturn IB, 5.5 percent ground wind model. Preliminary design investigation is in progress. Tests will be conducted at LRC 16' wind tunnel.

3. The following is a partial list of additional projects and their current status :

Visual Aid Gimbal Assembly (-F) Delivered

Modify Survey Probe Assembly (-AD) Delivered

Orbital Workshop Model for Area and Moment Determination (-AD) Del ivered

Slosh Force Measuring Device (-D) Fabrication Odyssey Display Model (-T) Delivered

~odificationl~e-design of Special Test Section 14" Wind Tunnel for 5" O.D. Fabrication Base Flow Models (-AM)

5" O.D. Saturn V Base Flow Model with Pressure Instrumentation for X-Beam - Des ign 14" W. T. (-AM)

Diaphragm Cutter Assembly for the High Reynolds Assembly (-AE) Fabrication

4 Percent Saturn V Force Model - AEDC (-AD) Fabrication

Remote Control Hardware for Floor and Ceiling Adjustment - TTS, 14" Wind Drafting Tunnel (-AE)

Temperature - Mismatch Test Section (-AT) Fabrication

5 Component, 112-inch O.D. Balance (-AE) Delivered

Variable Porosity Walls for TTS - 14" W.T. Delivered (-AE)

Saturn V, Thin Skin Heat Transfer Model - Fabrication JPL (-AE)

Flat Plate Model (NSL Design) - Arnes (-AD) Delivered

Free Oscillating Balance and Model Assembly (Lockheed Design) (-AU) Delivered

S- I1 "Hot Transfer Sidewall Assembly" (-AT) Fabricat ion

Major Components for High Reynolds Number Tes t Equipment (-AE) Fabrication

Flat Plate Model (NSL Design), 14" W.T. (-AD) Fabrication

Visual Aid Model (-DIR) Fabrication C. Aerodynamics Design Off ice

1. S-I1 Insulation Tests

Tests have been conducted in the MSFC 14" TWT to determine the structural integrity of Saturn V-S-I1 stage insulation under a simulated flight aerodynamic environment. Several 10 x 10-inch specimens of S-I1 insulation were tested at a Mach number of 1.80. The majority of the tests were conducted at flight dynamic pressures of 5 percent below, 25 percent above, and 45 percent above the maximum flight dynamic pressure. Various insulation defects such as cracks, debonded areas, cracks with debonded areas, and debonded bubbles were simulated during these tests. The conclusions based on the results of these tests are as follows :

(a) Cracks transverse to the flow up to six inches in length with and without debonding will not fail.

(b) Debonded areas up to six inches in diameter with or without cracks of any length up to the diameter of the debond will not fail.

(d) If a defect should occur that is a two-inch diameter or larger semicircular crack with debonding, then insulation failure would very likely occur and cause debris to travel down the vehicle during flight. However, since the probability that this type of defect will occur is small, the insulation probably will not fail if the differential pressure between the inside and outside of the insulation skin is kept small. Since these tests did not include internal pressurization of the test samples, the effects of a pressure differential cannot be assessed.

A memorandum presenting a detailed description of these S-I1 insulation tests should be completed by mid-October. Preliminary copies are available upon request.

MSFC wind tunnel tests were obtained on the impact characteristics of S-I1 insulation samples on Saturn V components also. The critical components are the fiberglas shroud on the LH2 feed line and tile aluminum engine shroud. The insulation was represented by actual pieces of the external nylon-phenolic laminate, which is the part most likely to be removed and which has the highest density. The target consisted of panels of fiberglas and aluminum of the same material and thickness as on the vehicle components. Insulation particles, which were injected upstream of the throat, were accelerated to supersonic velocities before impacting the panels. The target panels were sting- mounted at a 15-degree inclination to the airstream, identical to the slope of the shrouds on the vehicle. Data were obtained with Fastex cameras during the tests and by inspection of the panels after the tests. The movies showed that the particles tumbled in random attitudes and were practically unaffected by the curved flow field in the presence of the target. Inspection of the impacts which took place on the various targets revealed only smears of paint from the laminate with no penetration or scarring. The only deformations occurring were to the sharp metallic leading edge of the wedge holding bracket.

2. Saturn IB AAP Aerodynamics

The configuration for Saturn IB AAP with the nose cone shape has not been finalized. The configuration perturbations are (1) replac- ing Saturn IB APS units with Saturn V APS units, (2) decreasing the length and height of the solar panel conduits, and (3) adding a rocket tower to the nose cone for early nose cone jettison. Preliminary aerodynamic characteristics for the above configuration changes have been estimated and provided to control personnel for study. A small scale wind tunnel test will be scheduled as soon as a configuration is frozen.

The thrust of the nose cone separation rocket was decreased by 12 percent because of reaction on the nose cone. A side load of 0.12 (thrust) sin 3" exists because of a 3-degree cant of the tower engine.

3. Apollo-Saturn IB (AS-205) Static Aerodynamic Character is tics

The aerodynamic characteristics of the Apollo-Saturn IB vehicles were revised and are being published in NASA TM X-53657. These data, to be used for control, performance and structural analysis, are based primarily on wind tunnel tests of scale models. Total vehicle, vehicle component, lift-off, separation, and second stage aerodynamic characteristics are included. Total vehicle aerodynamics include static stability characteris tics, axial force characteristics, load dis tributions, and pressure distributions. These data are defined at various Mach numbers, with the exception of pressure and axial force coefficient distributions, which are presented at zero angle of attack. Vehicle components included are command module, launch escape system, and fins.

4. Static Stability and Axial Force Characteristics of the Apollo-Saturn IB (AS-205) Launch Vehicle

An analysis report of experimental aerodynamic tests conducted in the MSFC 14" TWT and the LTV 4-foot high speed wind tunnel should be published during October 1967. Included in the report are three-component aerodynamic force data which span a Mach number range from 0.50 through 2.99, an angle of attack range from -4 through +10 degrees, and a roll angle range of 0, 45, 90 and 135 degrees. 5. Static Stability and Axial Force Characteristics of a Proposed AAP-I1 Configuration

A preliminary AAP-I1 con£ iguration was tested in the MSFC 14" TWT during August 1967. An aerodynamic analysis report will be published during October 1967. However, this configuration has already been superseded. Further tests will be conducted when the vehicle geometry becomes more stable.

6. Evaluation of Flow Coefficients for Flat Plate Outlets in Support of the Saturn V Venting Study

NSL is conducting the experimental program in the Ames 6 x 6-foot supersonic wind tunnel. Minor tunnel and instrumentation problems, which have slowed the initial phases of the test, have been corrected, and double shift operation will be instigated to make up the 10s t time. The initial data look good. The test is expected to last approximately six weeks.

Test hardware for use in the MSFC 14 x 14-inch TWT is being fabricated in anticipation of a November test date. The tests at MSFC will complement the Ames investigation and will determine the feasibility of studying orifice flow coefficients in a small blowdown wind tunnel.

7. Orbital Aerodynamics

Lockheed personnel, under Schedule Order No. 83, have calculated orbital aerodynamic data for a configuration of the Orbital Workshop with the Command and Service Module docked to the Multiple Docking Adapter at port number 5. These data are presented in the f 01lowing memorandum:

"Orbital Aerodynamic Character istics for the Orbital Workshop with the End-Docked Command and Service Mo,dule (MSFC Drawing SK10-7298),11 R-AERO-AD-57-71, August 10, 1967.

8. Body of Revolution Viscous Cross-Flow Investigation

Model design has begun on a 4.0-inch diameter ogive- cylinder pressure model to be used during Phase IIb of the viscous cross-flow program. The model, which will be tested in the LTV high speed wind tunnel, will have 689 pressure orifices. To obtain this large number of pressure orifices without severely affecting the sting- to-model diameter ratio, the scanivalves will be located inside the model. A firm test date will not be established until fabrication of the model is approximately 75 percent complete.

Evaluation of wind tunnel data on force model tests is continuing. 9. Aerodynamic Characteris tics of the Aborted Saturn V Vehicle

Aerodynamic characteristics of the aborted Saturn V vehicle, published in NASA TM X-53656, are based primarily on wind tunnel tests of scale models. Total normal and axial force characteristics with local normal force, local axial force, and local pressure distributions necessary for performance, control, and basic structural analyses of the vehicle are presented. All results are presented for various Mach numbers between 0 and 3.0 and vehicle angle of attack variations between 0 and 16 degrees.

10. Induced Flow over Saturn V Vehicle Due to First Stage Engine Plumes

R-P&VE-V (Mr. Jankowski) requested an estimate of the maximum potential induced flow along the Saturn V vehicle on the pad due to S-IC engine plumes. These data, which are to be used for vehicle ground support equipment design verification, have been released in office memorandum R-AERO-AD-67-82.

11. Aerodynamic Characteristics for Apollo/Saturn V Lift-Off Analyses

Wind tunnel and analytical analyses have recently been completed to verify the aerodynamic characteristics and tolerances used for Saturn V lift-off analyses. The results of these analyses indicate small changes in the previously released nominal power-off aerodynamic characteristics (NASA TM X-53577 and Office Memorandum R-AERO-AD-67-15), and an associated increase in previously applied tolerances to encompass potential engine power-on effects. The new tolerances and data are being released in Office Mrmorandum R-AERO-AD-67-83.

12. Saturn V Lift-Off Aerodynamics

Static aerodynamic loads for the Saturn V launch vehicle as a function of lift-off attitude in the presence of the launch complex for varying wind directions were obtained from tests conducted in the LTV low speed wind tunnel using a 0.9 percent scaled model of the vehicle during the week of August 21, 1967. Loads were also obtained in the presence of a partially simulated engine exhaust plume.

The computer program which was written by NSL to calculate the flow field surrounding the Saturn V launch vehicle during lift-off has been completed. Several difficulties with these computations limit their value for this problem. Tests have been conducted using the MSFC 1/56 scale Saturn V cold flow launch deflector facility to obtain qualitative information about the flow field surrounding the Saturn V launch vehicle during lift- off. Visual techniques consisted of observing tufts which were taped to the vehicle and observing the trajectories of small (1116") styrofoam balls while the simulated cold flow engines were in operation.

13. Saturn V - Static Stability and Pressure Test

Testing of a 4 percent scale model of the Saturn V launch vehicle in the AEDC 16-foot transonic wind tunnel to determine high angle of attack static stability and detailed load distribution over the tailbarrel is now scheduled for November 27, 1967.

The model is now being fabricated, but the delivery date has slipped to October 2, 1967.

A conference was held at AEDC to discuss pretest problems of instrumentation and data reduction. Representatives of Aero-As trodynamics Laboratory (R-AERO-ADE), Computation Laboratory (R-COMP-RRP), and Northrop Space Laboratories attended.

14. Nonlinear Lift of Bodies of Revolution

On June 29, 1967, the Chrysler Corporation was awarded Contract NAS8-2078 entitled "Experimental Investigation of Nonlinear Lift of Bodies with Varying Cross Section." Phase I of this contract provides for the experimental determination of detailed pressure distributions on bodies of revolution with shapes as follows: (1) ogive- cylinder and (2) ogive-cylinder-frustum-cylinder. Phase I of the contract also provides for a flow visualization study which includes shadowgraphs, Schlierens, vapor-screen photos, and oil-flow studies. Phase I1 of this contract provides for an experimental survey of the vortex sys tem in the wake of the ogive-cyl inder-frus tum-cylinder configuration. All experimental measurements will be made in the MSFC 14" TWT at angles of attack of 0, 5, 10, 15, 20, and 25 degrees. Phase I tests will be conducted at Mach numbers of 0.40, 0.80, 1.20, and 1.96. Phase 11 tests will be conducted at a Mach nunber of 1.96.

The Chrysler Corporation has conpleted the design of the models and support equipment for the Phase I tests; their design has been approved by R-AERO-ADE. They have also submitted a Phase I pretest report for approval. D. Experimental Analysis Branch

1. Low Density Wind Tunnel

Calibration runs on the Mach 4 low density nozzle have been completed using the impact pressure probe and static pressure probe. The flow has been surveyed plus/minus twelve inches axially from the nozzle exit. This series of tests completes the calibration with ambient stagnation temperatures. During this time it will become necessary to cool the nozzle walls with liquid nitrogen to reduce the thick boundary layer of the rarefied gas flow and increase the isen- tropic core d iameter .

A helium refrigerator which became available after termination of an Aero Lab contract with Celestial Research Co. is being shipped to R-AERO-AEP. It will be used to increase the capability of the low density wind tunnel by allowing gases other than C02 to be used as the test medium.

Tests will resume on drag measurements in the rarefied gas flow as soon as a more sensitive drag balance is purchased.

2. Impulse Base Flow Facility

The first phase of the three engine parametric tests (AT-68) is now expected to begin in early October 1967. An improved diaphragm cutting mechanism has been incorporated on the model. Even after allowing for mass flow differences, the performance of the new supported- diaphragm cutter surpassed the old cutter.

3. High Reynolds Number Special Test Equipment

Construction has begun on the multi-purpose building which will house the High Reynolds Number Equipment. Contracts have been awarded on the following items:

(a) Supply tube

(b) Settling chamber

(d) Building.

Contracts on all remaining hardware are now being awarded. Assembly and checkout of this equipment is expected to begin in June 1968. 4. Thermal Acoustic Jet Facility

a. A test program on the cold flow duct to survey the total pressure in the plumes of the clustered jets on the S-11 cluster model is underway. Total runs 289.

b. An experimental investigation with a spark schlieren system in the cold flow duct is being made. The results of this test will be used as an input for the design of a high speed shock motion monitor by IIIRI. Total runs 13.

c. Repeat runs of a previous test on cold flow duct are being made. This phase consisted of a pressure survey of single nozzle plumes, using a traversing pressure probe. Total runs 20.

Performance tests of the Helium Heater at the contractor's plant revealed a design deficiency in the insulators of the new heater package. The fix appears to be easily accomplished, and delivery of the unit to MSFC is expected within two weeks.

5. 7 x 7-Inch Bisonic Wind Tunnel

An investigation was run to calibrate a 45-degree half- angle cone pressure probe manufactured by Boeing for Saturn V/S-I1 Stage base flow studies being conducted by R-AERO-AT at AEDC.

6. 14 x 14-Inch Trisonic Wind Tunnel

The following tests were run during August and September 1967:

(a) A test for R-AERO-AD, in conjunction with R-P&VE to determine the effect of the Saturn VIS-I1 stage nylon-phenolic outer laminate insulation covering particles impacting on simulated fairings and shrouds. The laminate particles were released in the tunnel still- ing chamber and moved downstream into the test section in the tunnel airstream. Total runs: 50.

(b) An investigation to determine the static longitudinal stability and axial force characteristics of the uprated ~pollo/~aturnI (AS-205) abort configuration. Total runs: 92.

(c) A forced oscillation test to determine the dynamic stability characteristics of the Saturn 203 and 206 forebody configura- t ions. This investigation was conducted by Lockheed for R-AERO-AU. Total runs: 92. (d) An investigation to calibrate and develop a probe or probes for measuring local Mach number and flow direction. These probes are to be used by R-AERO-AD in an experimental program to survey the vortex system in the wake of an inclined body of revolution. Total runs: 167.

(e) A test for the U. S. Army Materiel Command, Nike-X Project Office to determine the static longitudinal stability and axial force character istics of the SPEEDBALL, second stage (APACHE) con£ iguration with the Coast-Phase-Control-System (CPCS) Module. Total runs: 60.

The compressor is still inoperative and present operation is from Test ~ivision's3500 psi air supply. Work on the compressor system is continuing, and the compressor is now expected to be assembled, checked out, and back in operation on or before October 23, 1967.

7. Cold Flow Test Facility

The first runs were made in an investigation to determine if the nonsymrnetrical "pumping" effects of the Saturn V engine plumes traversing two different flame trenches of the launch pad will increase the normal aerodynamic loads for the power-on case with lift-off ground winds. Total runs: 8.

8. Atmospheric Crossed-Beam Field Testing

Field testing of the atmospheric crossed beam was started at the AMICOM 400-foot tower as a joint IITRI-MSFC effort. The systems were checked out and minor problems resolved. Only a few good runs were obtained because of poor weather.

The continuous bad weather experienced in Huntsville prompted an early change of test site to the Ft. St. Vrain tower near Colorado State University. The four anemometers, booms, cabling, etc., were removed from the 400-foot AMICOM tower for use in Colorado. These items are to be replaced at a later date. The instrumentation truck was driven to Colorado by a contract driver; the two telescope trailers, not being roadworthy, were transported by truck.

Two MSFC employees drove another vehicle, carrying smaller items of equipment. They will be at the site for approximately three weeks, for the installation, setup, and checkout of the system and some familiarization with the overall system. The equipment will remain at the site through next spring. 9. Instrumentation

Work continued on the real time digitizer system for the atmospheric crossed-beam program. The damaged digital magnetic tape unit is to be returned in late September. The system should be completed in late October. It probably cannot be used until next spring, however, as the crossed-beam equipment is in Colorado and we do not have travel funds to do any work there.

10. Data Reduction and Programming

The static pressure data from the supersonic phase of the Saturn V 4 percent acoustics were converted to cards and plotted. This plotting is about 80 percent complete.

A program was written to aid in the analysis of the starting loads of the High Reynolds Number Facility. Transfer function of the model-sting was assumed, various input functions were applied, and the outputs were calculated and plotted.

11. Orbital Aerodynamics Scanner Sys tems

The photo-cell scanner system is now ready for any use. Testing of the system, using circular and square shapes, indicated an accuracy of about 2 to 4 percent in area and about 0.1 inch uncertainty in centroid location.

E. Thermal Environment Branch

1. Voyager Thermal Environment

Work is nearing completion on a preliminary thermal environment for a Saturn VIVoyager launch vehicle and spacecraft. The environment is being generated from lift-off through spacecraft insertion into orbit around Mars. A dual purpose has been served by the study. In addition to producing a good preliminary environment,, the effort has provided an excellent opportunity to exercise the capability to compute a complete thermal environment including interplanetary environment predictions. Upon completion of the task, no further work in this area is anticipated until a better definition of requirements exists.

2. Entry Heating

Effort during this reporting period has been directed toward reprogramming a viscous hypersonic shock layer analysis to include the capacity to handle gas mixtures other than air. Additionally, an investigation has been undertaken to determine the form of correlation formulae which would allow the solution to be extended around a body away from the stagnation region. 3. Odyssey

Work has been completed on a thermal analysis of selected Odyssey experiments. Specifically, a study was made on the passive sphere experiment to determine a materials/ construction combination which gives a nearly uniform temperature distribution.

4. Orbital Heating Program

Documentation is complete and the program is now operational.

5. Saturn 205 Thermal Environment

The thermal analysis of the increased aerodynamic heating due to the addition of anti-flutter heat sections to the S-LVB forward interstage of Saturn 205 is nearing completion. The flow conditions in the hat section gap and surrounding areas have been established, and the heat transfer coefficients and recovery temperatures for the maximum heating trajectory are almost complete.

F. Unsteady Aerodynamics Branch

1. Saturn IB Ground Winds

Checkout of the dynamic characteristics of the Saturn IB/ Centaur ground winds model for modification to simulate AS-204 is continuing by Lockheed. However, completion of the checkout will be delayed until updated dynamic characteristics for the AS-204 are supplied by R-P&VE. R-P&VE is presently updating these dynamic characteristics using information obtained from the pull tests . R-AERO-AUE recently conducted a parametric study of predicted ground wind loadings for the AS-204 using assumed but reasonable values for the full-scale dynamic character istics. This in£ormation has been published and will soon be distributed.

2. Saturn V

a. Ground Winds

The design of the Saturn ~/~oyagermodel is nearing completion, and fabrication has begun at Atkins and Merrill. A meeting was held on September 20, 1967, at MSFC to discuss the model design and to coordinate the design with modifications of the existing magnetic damper sys tem.

Checkout and modification of the damper system by Lockheed have been partially delayed because of an inoperative power amplifier. The system is being checked out using the Saturn 1~1~entaur model. These checkout tests will continue as soon as the power amplifier is repaired or a new power amplifier, which is on order, is delivered.

b. Inflight Fluctuating Pressure and Acoustic Environments

Overall fluctuating pressure levels from the 4-percent Saturn V model scaled to full scale flight conditions have been submitted to R-P&VE-S. Also the first set of cross-power spectral densities have been machine-analyzed and are being scaled for R-P&VE-S in order that they may obtain more detail for their assessment of the structure. These pertain primarily to the forward skirt of the S-I1 stage and the IU.

Additional (500) cross-power spectral densities have been ordered; they will include the Service Module, IU, S-I1 forward skirt, RCS motors, APS, Ullage Motors, Command Module, Service Module, LEM, and S-IVB aft conical skirt. The additional cross-power spectral densities include both the longitudinal and circumferential directions.

3. Launch Site Acoustic Environments

a. Acoustic data from the AMTF at Test Lab. are still being analyzed for determination of effects of the flow differences between cone and bell nozzle engine configuration.

b. Acoustic data from model tests to determine the effects of clustering on acoustic power spectral characteristics are being recorded at Test Lab. The baseline single engine tests have been completed; however, the cluster tests remaining will be delayed because of low priority.

c. The phase correlation study of the acoustic field for the Saturn V 1120-scale model is also being delayed because of low priority. This study is designed to measure the spectral and spatial correlation characteristics of the acoustic pressure field on the Saturn V (S-IC stage) resulting from the rocket exhaust noise during launch.

d. The jet impingement acoustic data from Test Lab. are being analyzed at Test Lab. in the form of 113 octave bandtime histories and spectra on certain measurements. The data from the smaller 500- pound thrust engine study are available, and the 4000-pound thrust engine test data are to be completed by November. Priority has caused the major delay in this program output.

e. The full scale, horizontal, undeflected 5-2 engine firing has been monitored for several tests to acquire acoustic data. These data have been delivered for the first series of tests at one expansion ratio, and for the one chamber pressure value. More tests are to be monitored as soon as several Test Lab. problems with the test are resolved. f. A recalibration of the acoustic measurements on the S-IVB stage of AS-507 and 508 has been provided to Douglas. Recent wind tunnel data from AEDC warranted the modification of the levels to acquire the best coverage. Twelve measurements were involved.

g. In response to R-P&VE1s request for detailed environmental predictions of the acoustic environments for on-pad and inflight periods for MLV configurations of Saturn IB and Saturn V, the following memos have been prepared to provide spectra for each condition for the various zones on the vehicle. The overall sound pressure levels or fluctuating pressure levels are provided for the on-pad and inflight conditions, respectively.

1. "Response to Request for Acoustic Environments for MLV, Configuration - 3(MLV-SAT-IB-27)(MS-156)," R-AERO-AU-67-75, September 22, 1967.

2. "Response to Request for Acoustic Environments for MLV, Configuration - 3(MLV-SAT-IB-27)(MS-156)," R-AERO-AU-67-74, September 22, 1967.

3. "Response to Request for Acoustic Environments for MLV, con£ igurat ion - 4~(MLV- SAT-V-4 (s ) B) ," R-AERO-AU- 67 -7 3, September 22, 1967.

4. "Response to Request for Acoustic Environments for MLV, Configuration - 2(MLV-SAT-IB-5A),I1 R-AERO-AU-67-70, September 14, 1967.

5. "Response to Request for Acous tic Environments for MLV, Configuration - IC(SAT-IB Cone Vehicle)," R-AERO-AU-67-69, September 6, 1967.

6. 11 Response to Request for Acoustic Environments for MLV, Configuration - IB(MLV-SAT-IB-13-7B)," R-AERO-AU-67-67, August 30, 1967.

7. "~esponseto Request for Acoustic Environments for MLV, Configuration - [email protected])," R-AERO-AU-67-66, August 25, 1967.

4. Aeroelastic Characteristics of Saturn IB and Saturn V

a. Pitch Damping

Good results were obtained from the pitch damping tests on SA-203 and 206 forebody configurations which were completed on August 18, 1967. These experimental results were compared with predictions obtained from an approximate theoretical method using the linearized method of characteristics, and were found to agree within a few percent. This theoretical method is being expanded for use in pre- dicting the aerodynamic pitch damping of con£ igurations with more than one body discontinuity.

b. Quasi-Steady Oscillating Wake Study

The fourth phase of this study is now scheduled to begin in mid-October 1967, the test date having slipped from the previously reported end of September. An extensive calibration is included in this phase for support of earlier tests.

5. Aeroelasticity

The final report on the work performed under NASA Grant NGR-23-005-166 at the University of Michigan will be published as two separate articles. The first is entitled "Aeroelastic Stability of Plates and Cylindersff by W. J. Anderson, the principal investigator of the grant. In this report the linear stability criteria are presented for the panel flutter of thin plates and thin-walled cylinders. The analysis is accurate for the static divergence and coupled mode flutter of flat panels in supersonic flow and also for divergence problems wherein experimental measurements can supply the values for the necessary aerodynamic parameters. One result is to point out the importance of static instability for flat panels in a transonic viscous flow. A second result is to illustrate that the asymmetric divergence of cylinder shells is very sensitive to small changes in the pressure distribution.

The second report is entitled "Engineering Estimates for Supersonic Flutter of Curved Shell Segments." Here, design curves for rectangular segments cut from a circular cylindrical shell are presented in the form of a thickness parameter required to prevent flutter as a function of curvature and length-to-width ratio. The results are intended to aid in the design of wind tunnel models for panel flutter tests .

VII. DYNAMICS AND FLIGHT MECHANICS DIVISION

A. Multi-Projects

Rendezvous Guidance Targeting: A computer program has been developed that will generate launch window targeting data for the launch vehicle for position intercept or orbital transfer conditions for subsequent rendezvous with a target vehicle of a known ephemeris. The basic inputs to the program are (1) target ephemeris, (2) duration of desired launch window, (3) desired orbital transfer conditions, (4) target and pursuit vehicle venting data and attitude timelines, and (5) nominal flight time and range angle to perigee of the pursuit vehicle. The computer program will determine an analytical solution of the targeting data based on a spherical earth, vacuum, and no vehicle perturbations. The program uses these analytical solutions as first guesses for a numerical orbit integration which simulates the true gravitational field, atmospheric density, and propellant venting. A table of targeting data is formed and processed to generate a functional repre- sentation of the data. Further work will continue to increase the flexibility and reduce the required computer time. (DG)

B. Saturn V

1. Mission Profile

a. AS-503 Mission Profile

A joint effort between R-AERO-DAP and R-AERO-FO is being made defining a two-restart S-IVB mission for AS-503. The present thinking is that the SC/LM will get off in earth parking orbit and leave the S-IVB with about 150k propellant. A first restart burn of 70 seconds is being investigated with the "best" combination of constant pitch-yaw attitudes to insure tracking and communication coverage for a second restart approximately 80+ minutes after second burn cutoff. An attempt will be made to optimize the third burn such that there are approximately 70,000 pounds of propellant on board after the third burn and the flight trace crosses mainland tracking station to monitor a proposed simulation of the AS-504 fuel dump and impact in the Atlantic Ocean. The study is about 70 percent complete with a target date for a rough draft set at October 15. The final data will be presented to the Guidance and Performance Subpanel and or the Flight Mechanics Panel. A joint R-AERO-DAP/R-AERO-FO memorandum will be distributed soon.

A second 530-miss ion profile is being investigated based upon obtaining a larger nodal shift than the profile above. First, before the node change maneuver is made, the spacecraft is separated from the S-IVB stage. Then, the S-IVB stage is reignited for a 170-second,burn, slewing the line of nodes 32.8". After a coast of about one orbit, the S-IVB makes a third burn over Bermuda tracking station with a fixed attitude (along the velocity vector) for a duration so as to leave 55,000 pounds of propellant on board (about 28.4 seconds). (DAO)

b. Dual Thrust

A dual thrust system for application to F-1 engine for use in the Saturn V program has been investigated and documented in Memorandum R-AERo-~Ap-53-67. The addition of the dual thrust system

4 1 to the F-1 engine results in a payl-oad increase of approximately two thousand points at TLI. Apparently no major vehicle impact is realized from this mod if ication, maximum dynamic pressure is less than 750 pounds per sq. ft. and maximum acceleration at IECO equal 4.3 g's. Work is about 60 percent complete on a dispersion analysis of the effects of the dual thrust system and approximately 25 percent on an investigation of engine-out influences. (DAP)

c. Disposal of the S-IVB Stage on the Lunar Mission

A feasibility study of the possibility of using the residual propellant left on the S-IVB stage after translunar injection to obtain enough AV to cause the stage to escape the earth-moon system has been completed. The study showed that there is a relatively high probability of obtaining this effect. The AV would be applied along the negative velocity vector resulting in a slowing down of the stage causing it to pass behind the trailing edge of the moon. The stage would pick up sufficient AV from the gravitational effect of the moon to escape the earth-moon system. Methods of implementation are now being investigated. (DAM)

2. ~~namicsand Control

Saturn V Instrument Unit Local Deformations: A correlation study was conducted to determine the cause of local deformations at the EDS gyro package in the Saturn V instrument unit. The deformations were found proportional to the bending moment at the instrument unit. The proportionality constant is being used by Boeing to predict the local deformations for flight vehicles until the structural model can be improved to include such effects. (DDS)

3. Project Information Applicable to Many Vehicles

a. Current Performance

TBC is implementing the changes in the Saturn V current performance requested in R-AERo-~Ap-38-67 (namely, that 504 and subs, current performance, employ the same propulsion model used in the 504 Reference Trajectory, TBC document ~5-15481-1). Changes in FPR and FGR are being incorporated into the current performance report in response to a telephone conversation between R-AERO-DAP and TBC. All changes and modifications should be completed in October. (~~~/~oeing)

b. Ring Baffle Requirement for Saturn V Synchronous Orbit Vehicle

A study of slosh baffle requirements for the S-IVB/V Synchronous Orbit Mission is reported in R-AERO-DD-41-67. As a result of this study, it was recommended that provision be made for an additional baffle location in the LH2 tank. (DDS) 4. Project Information Applicable to Individual Vehicles

a. Saturn V Dynamics Data

Revised torsional vibration analyses for the AS-501 and AS-502 vehicles have been issued. These revisions account for the recent modification of the CM-SM interface structure. (~~S/~oeing)

b. 501 Control Stability Re-evaluation

The results of a root-locus stability analysis for the AS-~O~/S-ICstage flight vehicle are presented in Memo R-AERO-DD- 48-67. This study, which includes local bending effects at the rate gyro location and the final AS-501 control system provided by the Astrionics Laboratory, shows the control system to have adequate stability in elastic body and sloshing modes. (DDD)

c. AS-501/S-IVI3 Low "g" Slosh

A draft of the final documentation of digital studies on low "g" slosh on AS-501 has been delivered by Northrop. This study made use of a DSL-90 simulation which eliminates all of the scaling and drift problems encountered in analog runs. (DDD/Northrop)

C. Saturn IB

1. Dynamics and Control

a. Uprated Saturn I Rigid Body Response Analysis

Apollo configuration aerodynamic data were revised resulting in a forward shift of the center of presssure envelopes. The effects of this revision on rigid body responses were studied by comparing responses obtained with the previous aerodynamic data to those obtained with the revised data. The following table presents the peak responses of angle of attack and gimbal angle resulting from forcing the nominal vehicle with the 95 percent synthetic design wind profile.

Case Old Aerodynamics New Aerodynamics

Mach 1 7.0" .83" 7.0" 1.75"

Max qa 7.0" 2.4" 7. 1" 4.6"

Max q 6.3" 6.3" 6.4" 6.2" With allowances for vehicle perturbations and flexible body demands on gimbal angle, the limits of gimbal throw angle are being approached for the Apollo configuration.

The engine-out capability is also expected to change adversely because of the new aerodynamics. Preliminary results indicate that an engine-out capability will not exist under some circumstances with the system gains as presently defined. This is being investigated more thoroughly . (DC)

2. Project Information Applicable to Many Vehicles

Uprated Saturn I/CSM (2.5 Stages) to Orbit: A preliminary study has been completed for performing a sub-orbital start of the SM. The orbital was 81 x 120 nautical miles with an inclination of approximately 28.50. The SM was cons trained to burn 15,000 pounds of propellant for the nominal trajectory. There was no coast between S-IVB cutoff and SM ignition. Data were also generated for burning 10,000 pounds of SM propellant, and early shutdowns of the S-IB inboard engines were investigated. For the nominal trajectory, a payload of 40,568 pounds was placed into orbit, and payload of 40,212 pounds was attained for burning 10,000 pounds of SM propellant. S-IB inboard engine cutoffs of 10 and 20 seconds before outboard cutoff yielded changes in nominal payload and longitudinal acceleration of 388 pounds, 1.95 m/sec2 and 978 pounds and 4.45 m/sec2, respectively. (DAP)

3. Project Information Applicable to Individual Vehicles

AS-204 Nose Cone Separation for Abort: A study to indicate the earliest time at which it is feasible to jettison the AS-204 nose cone in the event that the S-IVB stage engine fails to ignite is near completion. Results indicate that it is possible to jettison the nose cone in this event at least as early as in the case where the S-IVB stage engine does ignite and subsequently fails. Contacts with I-MO personnel at MSC indicate that they need relative motion trajectories for alternate mission planning. These trajectories have been computed and are now being prepared for publication. (DC)

D. Saturn Apollo Application Program

1. Cluster

a. Mission Profile

(1) Baseline Mission Description Document for AAP-2: A 16-man month effort has been initiated under the Phase C payload integration contract extension with Martin Company to develop a mission description document. This document, when completed, will consist of seven volumes which summarize the data and analysis necessary to define the vehicle, experiments, and f lightlmiss ion requirements and constraints for AAP-2. Data to be included are mission description, detailed reference trajectory, detailed integrated mission timeline, attitude timeline, mission support requirements, subsys tern requirements, and alternate mis- s ion and contingency plan. (~AMIMartin)

(2) Mission Timeline for AAP-314: A 15-man month effort has been initiated under the Phase C payload integration contract extension with Martin Company to analyze the individual experiment performance requirements of Flight 314 experiment candidate group to consider the astronaut time, power, spacecraft and experiment orientation, light conditions, and all other performance schedule. (DAM/Martin)

(3) AAP-4 Mission Utilizing Elliptical Orbits: The AAP-314 mission plan at this time calls for launching the AAP-3 vehicle into a 120 n.mi. circular orbit via an 80 x 120 n.mi. elliptical transfer to the 120 n.mi. circular orbit. After one day, the AAP-4 launch vehicle is to place the IXIATM into a 160 n.mi. circular orbit. The AAP-3 (CSM) is then to transfer and rendezvous with the LM/ATM and then the docked configuration will rendezvous with the orbital workshop in approximately a 240 n.mi. circular orbit. Now if the AAP-4 launch vehicle does not meet lift-off the following day, the difference in the nodal regression of the workshop and the CSM will cost approximately 40 meters per second per day velocity correction provided the maneuver is applied at the orbital line of nodes. This means the CSM will be inserted into the workshop orbit immediately to conserve fuel and make the mission more flexible.

A study of the AAP-4 (LM/AIM) has showed that if the perigee of an ellipse is fixed at 90 n.mi. and the apogee fixed at 650 n.mi., the performance requirement is equivalent to a 160 n.mi. circular orbit. If an intercept rendezvous concept is used and the apogee dropped to 300 n.mi., approximately 2,500 pounds can be saved. This means that the CSM would transfer into an 80 x 290 n.mi. ellipse at the intercept point and achieve a co-elliptical transfer with the IMIATM (90 x 300 n.mi.). The AV required to achieve this is not much greater than dropping from a 240 n.mi. orbit to a 120 n.mi. and back up again. All of these possibilities for saving payload should be studied closely before accepting a set plan for achieving rendezvous. Further details will be forthcoming in a memorandum. (~G/Northrop)

(4) CSM and LM/ATM Mission Profile Trade-offs: Two mission profiles have been investigated for CSM propellant expenditure in the dual rendezvous of CSM/A?M-ows in the AAP-3/AAP-4 mission. One profile requires the CSM to transfer from its injection orbit (81 x 120 NM) directly to the OWS orbit (257 NM circular) then after launch of ATM initiate dual rendezvous from the OWS orbit. This profile is being considered to reduce the plane change requirement resulting from nodal regression rate difference between separate CSM and OWS orbits. The other profile, which is the standard being used for preliminary mission planning, requires the CSM (after injection into an 81 x 120 NM orbit) to remain in a 120 NM circular waiting orbit until ATM is launched, then from that 120 NM altitude initiate fuel rendemous. The circular injection altitude of the AM has been varied in the 257 NM waiting orbit profile leading to a plot of CSM propellant expenditure vs ATM injection altitude. A fixed ATM injection altitude of 160 NM has been assumed for the 120 NM waiting orbit profile. Some interesting data have resulted from a comparison of the two profiles. For example, in the 257 NM waiting orbit profile, the CSM propellant expenditure for transfer from its injection point to the OWS is 1,850 pounds and for AM injection at 160 NM, the dual rendezvous from OWS altitude requires 3,030 pounds of propellant, giving a total of 4,900 pounds for the complete set of maneuvers. For the 120 NM parking orbit profile, the total propellant required for dual rendezvous (with ATM at 160 NM) is 2,775 pounds. However, this expenditure does not include the 542 pounds per day (at 120 NM) plane change propellant penalty. A lesser propellant penalty is incurred for higher altitude waiting orbits. Even so, unless long duration waiting times of several days were involved, it would not pay for the CSM to go to a 257 NMwaiting orbit altitude. The results of this study are tb be used as an aid for establishing firm vehicle insertion altitudes for AAP-3/4. (DAO)

(5) Cluster 1,Mission Trade-Off: A study is being made to point out the trade-offs resulting from either reducing the guaranteed lifetime of the cluster mission or schedule relaxation (increased lifetime from decreased solar activity). The effect would be to gain workshop (AAP-2) payload capability due to lower insertion altitude and a reduction of AAP-1 and 3 service module propellant requirements. Gains from slipping the launch schedule one year are a payload increase of 950 to 1700 pounds, an AAP-1 propellant reduction of 110 to 190 pounds and an AAP-3 propellant reduction of 200 to 370 pounds. The effects of reducing guaranteed lifetime to 240 days (LMIATM lifetime 60 days) are generally larger. The stated variations in the above examples result in the uncertainty of workshop solar panel orientation during the storage periods. (DAO)

(6) Satellite Occultation in Earth Orbit: This study has been completed and documented. The total variation in percent of orbital period in sunlight of the workshop (260 n.mi. inclination 29") was found to be from 62 to 70.5 percent. If the workshop is launched on July 1, the sunlit percentage of the orbit will be 62 percent increasing to70.5 percent six months later. A December 1 launch has the opposite variation. (DAO) (7) J-2s Ennine Restart: At present, the J-2s engine production units are to be available by January 1970 and qualification tests will be completed by mid-1970. The first J-2s engine may use a solid propellant gas generator for starting in lieu of tank head starting. NPSH requirements will be qualitatively lower than the present 5-2. Because of other pressing studies, an integrated J-2s engine restart trajectory has not been obtained. However, an impulsive study shows that the J-2s restart mode can yield 7,300 pounds of payload wer direct injection to 260 NM, considering required restart propellant and approximately 2000 pounds of hardware additions. (DAO)

(8) Dual Rendezvous of Spacecraft: The study has been refined to use a newly developed 3-D orbital rendezvous computer . program - containing a terminal phase rendezvous scheme which is both simple and practical. The scheme is based on forcing a null rotation rate of the slant range between two vehicles and thrusting in accordance with passage through velocity "gates." By considering the target and pursuit vehicle velocities broken into components along and normal to the slant range direction of the vehicles, the null rotation rate criteria are developed by equalizing the normal velocity components of the target and pursuit vehicles. The velocity "gate" requirement defines a velocity in the slant range direction, and the summation of the components gives the desired velocity. Thrusting. is directed along the delta velocity vector between the desired velocity and actual velocity of the pursuit vehicle. Cutoff occurs when the desired velocity and actual velocity are equal. By the use of this technique, terminal rendezvous has been accomplished with only a few meters separation and a fraction of a meterlsec. delta velocity. The propellant expenditure has also proved economical. (DAOtNor throp)

(9) First Cluster Mission Decision Logic: Large mission decision logic displays have been generated in a combined baseline- module form depicting UP-112 launch insertion and rendezvous, OWS cluster operation and UP-314 launch, insertion, and dual rendezvous. The charts are developed for a manned-unmanned order of launch with the nominal mission constituting a continuous baseline running the length of the charts. In addition, the logic is developed in enough detail to serve as a flow chart for the main routine in the mission success probability program being generated under the direction of DAM. (DAOINor throp)

b. Guidance

AAP-3 Three-Stage Launch Vehicle Guidance: The AAP-3 mission calls for using the S-IVB stage to deliver the CSM into 80 x 120 n.mi. ellipse, and-after transit to apogee, the CSM is to circularize at a 120 n.tni. orbit. Preliminary studies indicate that if the propellant loading of the S-IVB stage and the CSM is altered to allow the S-IVB stage to thrust to fuel depletion and the CSM take-over and thrust to the 80 x 120 n.mi. ellipse, a significant payload increase can be realized. An MSFC interpretation of the MIT guidance equations was used to steer the CSM after S-IVB fuel depletion. The three-stage itera- tive guidance mode equations were used in which the coast period between S-IVB cutoff and CSM ignition and the CSM performance characteristics were included in the IGM closed intervals in order to have near optimum take-over conditions for the CSM. This type of formulation allows the S-IVB stage to be steered with the knowledge that the CSM is taking over. The MIT guidance system gave an acceptable orbit and met equivalent performance with the IGM simulation to CSM cutoff. At the present time, only two-stage guidance equations exist for the uprated Saturn IB vehicles. A coast period and an additional stage would have to be added to the guidance equations to offer this flexibility. The impact of this change in the instrument unit has not yet been assessed by Astrionics Laboratory. The two-stage guidance equations can be used by extending the burning time beyond S-IVB fuel depletion by a few seconds and selecting targeting data from that point (six seconds beyond fuel depletion). The two-stage guidance equations steering toward a pseudo-targeting point will give compatible take-over conditions for the MIT guidance system at CSM ignition even under 3-s igma vehicle perturbations. The CSM flight performance reserves for Saturn IB perturbations are only slightly higher with the two-stage equations as compared to the three-stage guidance equation. The two-stage ICM equations seem more desirable than the three-stage IGM equations from the standpoint of orbital plane enforcement. The MIT guidance system does not have rigid orbital plane enforcement capability. If the desired orbital plane at CSM cutoff is specified at the pseudo- target point, then there will be no plane change required of the CSM. The three-stage guidance equations would take out only part of the plane change required by S-IVB fuel depletion; this can be an expensive and essential orbital correction for a rendezvous mission. The results of this study will be published soon. (DG)

c. Dynamics and Control

(1) AAP-Cluster Dynamics: Preliminary normal mode vibration analyses have been completed for six configurations which occur during assembly of the AAP cluster. The results have been for- warded to Astrionics for use in control system design. Efforts to improve the analytical results will continue. (D~SJLockheed)

(2) Active Control Studies: The problem of controlling an orbiting vehicle by means of control moment gyros has been investigated. The application of the direct method of Lyapunov leads to a set of control laws that are asymptotically stable. The results thus obtained are similar to what is known as the decoupled control system investigated by Lockheed. The satisfactory results obtained by Lockheed were verified by a digital program simulating the CMG control of a rigid space vehicle. The results obtained seem to be superior to those of the Langley control, but the functional relationships appear to be too complex to implement.

Development of an in-house program which includes aerodynamic and gravity forces and torques for attitude control studies is continuing. Passive control run studies have been made. Active control methods are now being incorporated into the deck.

The study to determine CMG SIWAC desaturation capability has continued. The method studied is to attempt to desaturate the inner gimbals while using the outer gimbals for maintaining control. The studies, which thus far look feasible, have indicated the ability to desaturate each gimbal separately and maintain control with very small deviations.

Three different control laws were used in the CMG SIWAC control studies : linear, uncoupled, and Kurzhals . Instability appeared when the inner and outer gimbals reached 70 degrees for the Kurzhal control law. For the linear law, the system went unstable for smaller angles. The uncoupled control la* maintained satisfactory control but computer requiremeLts were greater than for the others. (~CAILockheed)

d. Project Information Applicable to Individual Vehicles

(1) SJA/Nose Cone Separation as an Integral Piece: Development of a scheme to jettison the SLA and nose cone as an integral piece from the S-IVB stage and Multiple Docking Adapter during the early part of S-IVB stage burn for the AAP-flight has continued; two additional studies have been made with more refined input data and an additional configuration. Feasibility of the scheme with adequate clearance both as the SLA clears the MDA and for possibility of recontact is shown in each study. Results of the studies have been documented in two memos: R-AERO-DCC-7-67 dated September 15, 1967, and R-AERO-DCC-8-67 dated September 25, 1967.

Since trajectories of the SLA/nose cone relative to S-IVB stage have been found, they can be used to determine clearance on the AAP-4 flight also. (DC)

(2) AAP-2 Rigid Body Controllability Analysis: A rigid body controllability analysis of two configurations of the AAP-2 vehicle has been completed and is being prepared for transmittal to R-TO. The purpose of the analysis was to provide information useful for evaluation of the relative merits of the two configurations. The 95 percent wind envelope peaking at the maximum q time point was used in the analysis. The first configuration investigated had 12-inch solar panel conduits mounted on the S-IW stage. This configuration was controllable under both the nominal case and a .4 caliber center of pressure dispersion case. The engine gimbal limits were reached in the dispersed case.

The second configuration investigated had 18-inch solar panels and the Saturn V APS modules on the S-IVB stage, as well as a nose coneiSLA jettison rocket mounted forward. Control for this configuration was maintained for the nominal case although the engine gimbal limits were reached. However, for .4 caliber center-of-pressure dispersion, the vehicle was unable to maintain control. This configuration has therefore been eliminated from further consideration. (DC)

2. AIM Pointing Accuracy

A six-man effort has been initiated at Northrop in support of program development and system analysis for ATM pointing accuracy studies. The immediate goal 'is to produce a computer program for analyses considering a two-body elastic system with both RCS and CMG control. (~~~iNorthrop) VIII. FLIGHT TEST ANALYSIS DIVISION

A. Special Projects Office

1. Saturn V

The Saturn V Flight Test Evaluation Plan, which is the basic directive for flight reporting of vehicles AS-501 through AS-504, was published on August 1, 1967. FEWG splinter meetings were held at NAAISD, Seal Beach, California, on August 1 and 2, at DAC, Huntington Beach, California, on August 3, and at TBCIMichoud, New Orleans, La., on August 4, 1967. The purpose of these meetings was to identify and discuss resolutions of evaluation problems for the last time in large meetings before the AS-501 launch, with special emphasis on problems involving data flow. As a result of these discussions, some revisions to the Saturn V Flight Test Evaluation Plan are now being published.

2. Apollo Applications

The AAP Payload Evaluation Plan, now ready for publication (MPR-SAT-FE-67-2), gives the overall organization and establishes general responsibilities and procedure guidelines. Because of the anticipated diversity of payloads, a specific evaluation plan will be documented for each mission to coordinate the efforts of the various disciplines and agencies in the post flight evaluation.

Measurement selection criteria for flight evaluation are being developed in response to R-TO efforts to define the overall flight measuring program for AAP payloads.

3. Seminar

The first volume of papers from the Environment Induced Orbital Dynamics seminar has been distributed. Eight papers, three references for papers that have been published, and the attendee list are included. Volume 11, which contains the remaining papers available, is now being assembled.

B. Flight Mechanics Branch

1. SaturnIB

The AS-2041LM-1 Launch Vehicle Operational Flight Trajectory (Revision l), R-AERO-FMR-184-67, dated August 10, 1967 has been distributed. Addendum 1 to SA-204lI.M-1 Range Safety Analysis, R-AERO- FNR-181-67, has been distributed.

The revision to the operational trajectory and the addendum to the range safety analysis reflect a 6 seconds longer S-IVB stage burn time.

The AS-204lI.M-1 Launch Vehicle Operational Alternate Mission Trajectories, R-AERO-PMR-193-67, dated September 8, 1967, has been distributed. This report is based on the nominal trajectory presented in the 204lI.M-1 (Rev. 1) operational trajectory document.

b. AS-205 Rendezvous Mission

The AS-205 typical trajectory profile to a 120 x 150 nautical mile elliptical orbit, R-AERO-FMR-199-67, dated August 25, 1967, has been distributed. This trajectory reflects a 36,300 pound spacecraft weight. With this weight, the S-IVB stage useable propellant at insertion is approximately 1600 pounds.

The S-IB stage, chi polynomial and S-IVB stage IGM pre- settings for this mission were distributed under memorandum R-AERO-FM- 179-67, dated August 8, 1967.

Because of the high insertion altitude of the 205 mission, a re-entry "g" problem exists if abort occurs during about 200 seconds of S-IVB stage flight. A considerable amount of effort has been expended searching for ways to relieve the problem. The work should be completed about November 15, 1967.

c. 206 Restart Mission

A rough draft of the operational trajectory has been received from CCSD. A majority of the work on the range safety and dispersion analyses has been completed. All of these data should be distributed during the month of October.

d. 2061207; 2081209; 210/211; 212 Missions

Preliminary work shcedules have been established for these missions. The 207 Launch Vehicle Operational Flight Trajectory Dispersion Analysis, R-AERO-FM-192-67, has been distributed, and the fixed-time partial derivatives to be used in the spacecraft dispersion analysis have been transmitted to MSC. 2. Saturn V

The final range safety Cape tape, which was delivered to KSC on August 5, 1967, was composed of 20 different variations and a nominal. Five additional engine-out cases have been completed for KSC.

The dispersion analysis has been corrected by TBC and distribution made by R-AERO-FMT.

Revision C of the operational trajectory has been checked and is now being distributed.

An overspeed study involving 6 cases from lift-off to re-entry has been completed and delivered to MSC through the Guidance and Performance Subpanel.

The abort and alternate mission document has been corrected .by TBC and distributed by R-AERO-MT.

The dispersion analysis has been checked, and approved without change.

Identification of components is almost complete so that the survivability analysis can be run on the 502 laun vehicle. Modification of orbital debris computer programs to run c. .he Univac 1108 computer should be completed by the end of November

A first-stage tilt program to meet the demands of KSC is being developed. NSL will do an S-shape tilt program study.

Work is continuing on the dispersion analysis. GFDA propulsion data are being checked closely to avoid the recurrence of errors in the GmA propulsion data found in the 502 data.

d. Lunar Landing Mission

R-AERO-FMT has developed the MSC/MSFC Joint Space Program (ARMPT) Deck to the point where flight to the moon and back to the earth can be completely simulated. This deck contains all the items necessary to do rapid targeting with the only problem being core to do the search routines -- which is, of course, the heart of the program. It is hoped that by mid-November our capability will be canplete. Official documentation is not yet available concerning the July exercise in rapid retargeting. However, at a status meeting, the following objectives were accomplished:

(1) Our first cut MSCIMSFC links are closed.

(2) The TLI targeting routine is operational.

(3) Automation was demonstrated by targeting through 10 azimuths consecutively without leaving the machine.

14) TLI targeting and TLI targeting verification links are operationa; that is, staging on computer to run TLI verification passes with IGN and vice versa.

(5) Total targeting computer time has been cut in half.

Only one major problem exists, and that is the TLI verification program itself. Although working, it can be initialized in earth parking orbit; hence, the computer time for an IW-TLI verification is excessive. A reconstructed program is being developed which could solve this problem eventually.

3. Apollo Applications

A range safety analysis for optimum flight profiles into an 87 x 140 n. mile orbit with orbital inclinations of 35, 40, 45 and 50 degrees has begun. These flight profiles, for both northerly and southerly launches with no yaw maneuvers, are to be completed by November 15, 1967.

4. Voyager

The range safety analysis, which has been completed for the Saturn V Voyager mission for launch azimuths of 45 and 115 degrees, includes spent stage impacts; nominal, maximum and minimum performance trajectories; velocity vector turning rate capabilities; and a probability analysis. . Tracking and Orbital Analysis Branch

1. Saturn IB

(1) The analysis of the orbital decay and lifetime for the AS-204 S-IVBIIU, documented in memorandum R-AERO-FT-53-67, is based on the final operational trajectory.

(2) A joint R-AERO-FT and R-AERO-FM memorandum, R-AERO-FT-56-67, presenting Bermuda coverage of the launch phase for various contingency cases for flight control purposes, has been issued.

(3) The analysis of AS-204lLM-1 launch vehicle tracking and communications, performed by CCSD, was distributed under cover memorandum R-AERO-FT-55-67.

(4) Magnetic tape information based on AS-204lLM-1 was sent to CCSD, DAC, and IBM, to comply with agreements with Mr. 0. Ely, R-ASTR-I. This tape contained time tables of slant range, elevation, azimuth and look angles for various tracking and communications sites.

A preliminary copy of the AS-205 orbital tracking and communications coverage timelines was given to Mr. Cremin, R-AERO-DAB and Mr. Jensen, R-P&VE-PTP.

Preliminary tracking and communications timelines on the AS-206 restart mission have been received from CCSD.

2. Saturn V

(1) The AS-501 tracking and communications coverage document prepared by TBC was received and distributed under cover memorandum R-AERO-FT-61-67.

(2) Magnetic tape information based on AS-501 was sent to NAA, TBC, DAC, and IBM, to comply with agreements with Mr. 0. Ely, R-ASTR-I. This tape contained time tables of slant range, elevation, azimuth and look angles for various tracking and communications sites. b. AS-503 Restart Studies

(1) Preliminary analyses on the AS-503 restart mission were presented at the G&P Subpanel Meeting held at MSC on August 3, 1967. Mr. Toelle, R-AERO-DA, presented all data prepared jointly by R-AERO-DA and R-AERO-FT. A joint memorandum to the G&P Subpanel was prepared documenting results. (R-AERO-FT-54-67).

(2) The results of additional studies performed on the AS-503 restart mission based on action items from G&P Subpanel Meeting of August 3, 1967, were presented to representatives of R-AERO, R-ASTR, R-P&VE, and I-MO on September 1, by Mr. Benson. The presentation, which included joint efforts of R-AERO-DA and R-AERO-FT, was essentially a "pre-meeting" to determine what was to be presented at the G&P Subpanel on September 7. Some additional studies, identified as possible candidate profiles for the AS-503 restart mission, were to be carried out after return from the G&P Subpanel meeting on September 7. Mr. Coulter presented the AS-503 restart data at the September 7th meeting at MSC. A joint memorandum will be prepared documenting the additional studies.

The AS-504 tracking and communications coverage document prepared by TBC has been reviewed twice and rejected twice. The new submittal date for the document is September 29, 1967.

3. Apollo Applications

a. Cluster I Mission

(1) Several studies which have been completed on the orbital decay and lifetime of the Cluster I Mission include the latest information on the orbital configurations, masses, and aerodynamic parameters and include parametric studies for various altitudes and various launch periods. Memorandum R-AERO-FT-53-67 and R-AERO- FT-62-67 documented the results. Other studies are continuing.

(2) Lifetime and decay studies for an alternate mission for the AAP-3 and AAP-4 vehicles are presented in Memorandum R-AERO-FT-60-67.

b. General

(1) Meetings have been held with representatives from the Martin-Marietta Corporation on branch task to be performed under the AAP integration contract. Martin-Marietta is to write detailed descriptions of these tasks and include them in a total work package. They will be reviewed at least one more time before contract negotiations begin.

(2) Attitude Prediction

(a) The theoretical study of attitude motion by Dr. James C. M. Yu is being published.

(b) Orbital Workshop (OWS) con£ igurations are being run on the computer to determine gravity gradient and solar radia- tion stabilization.

(c) The theory developed for a direction cosine integration scheme in the attitude prediction program is being programed and verified. The present program gives undesirable singularities in the attitude angle plots for angles at 90, 180, 270, and 360 degrees. The direction cosine integration scheme will eliminate these singularities.

4. Voyager

a. Representatives of R-AERO-G, and R-AERO-P attended a presentation on July 28 by Boeing of Seattle on some of the Navigation and Guidance analysis work they have performed on the Voyager Program. Of particular interest was the Orbit Determination Studies that have been performed. A limited number of copies of the presentation will be available. TBC, informed of our interest in the mission operations area, will attempt to schedule a presentation on their mission operations work on lunar orbiter.

b. A memorandum (R-AERO-FT-51-67) presenting the results of the Fourth Mission Operations Working Group meeting held at JPL on July 26, 1967 was distributed. All objectives, primarily the publishing of mission operations plan, have been achieved; this was the terminal meeting of the MOWG.

c. Mr. Fleischmann and Mr. Smith attended the Fourth Meet- ing of the Voyager Trajectories Performance, Navigation, and Guidance Working Group held at Langley on August 7 and 8. Mr. Fleischman presented lifetime studies on the canister in Mars orbit.

d. Analyses performed under action item 4-7 of the Fourth Meeting of the Trajectories, Performance, Navigation, and Guidance Work- ing Group, are now complete. The action item stated that an analysis of the magnitude of gravity gradient torques and aerodynamic drag torques for the Voyager spacecraft in a 1,000 km by 10,000 km orbit about Mars was desired. In order to examine the maximum torques experienced by the spacecraft, the following assumptions were made:

(1) The spacecraft was in a 1,000 km circular orbit about Mars.

(2) The attitude of the spacecraft was such as to produce the maximum torques at 1,000 Ian.

(3) The spacecraft contained no propellants or mwing parts.

(4) The Smith-Beutler atmosphere was used.

Applying these assumptions, it was found that the magnitude of the gravity gradient torque is .002 newton-meters, and the atmospheric drag torque is at most one order of magnitude less than the gravity gradient torque. Data have been given to Mr. McAnnally, R-AERO-P.

e. In response to an action item from the Voyager Trajec- tories, Performance, Navigation, and Guidance Working Group, an analysis was performed on solar gravity and solar pressure perturbations on the Voyager orbiter in a Mars orbit. Results are presented in Memorandum R-AERO-ET-59-67.

5. Contracts

a. The Bissett-Bemn Corporation under contract entitled, "A Study of Orbit Error Analysis," has delivered a computer program to perform error analyses on interplanetary trajectories. Analyses will pertain to accuracies in position and velocity which can be determined by ground based tracking systems assuming various error sources. A draft of the final report for this contract has been reviewed and comments given to B&B Corporation. Mr. Hal Dale of the B&B Corporation spent two days with members of the branch as well as Mission Support personnel discussing the program and the final report.

b. Honeywell, Inc., gave a presentation to Laboratory personnel on their efforts under contract entitled, "Study of Automated Planning," a study which was to determine the feasibility of linear programing as a tool for optimum experiment scheduling. Results indicated that linear programing is feasible with some reservations. Copies of the final report should soon be available.

c. Copies of the final report on the Graphic Lifetime Contract with LMSC have been received. The report contains normalized lifetime information for both Mars and Venus orbiters. d. A draft of the error analysis technique survey (first phase of the Mars Transfer Trajectory Error Analyses Contract) has been received and is being reviewed. Martin-Marietta of Denver was at MSFC on September 19 to receive comments on the survey and direction on the next phase of the contract.

6. Other

a. A draft copy of a prospective technical note entitled, "A General Analytical Method for Artificial Satellite Lifetime Determina- tion," by Frank Garcia, Jr., of MSC has been received for information and comments before publication. Comments were submitted to Mr. Grant of MSC in a letter dated August 14, 1967.

b. Mr. R. Benson presented a one-hour lecture on Orbital Decay and Lifetime at the Fifth Annual Suwner Lecture Series in Aerospace Science and Engineering held in Morris Auditorium on August 25, 1967. These lectures are presented to smer employees of MSFC and AMC.

c. Mr. Malone, R-ASTR, has requested that an internal note be prepared to document work performed by R-AERO-FT on the LEM Relay Communications Systems. This work was done in support of R-ASTR approximately eight months ago and was not published because of the status of this project. We are now finishing the work and should be able to publish soon.

d. An unsolicited proposal from Alabama A&M College was received and reviewed for possible research funding. The proposal was to perform an analog investigation of satellite orbits and the perturb- ing forces affecting these orbits. In essence, all work proposed has already been accomplished through use of digital computer programs to a much higher degree of accuracy than could be attained through analog simulations. The evaluation and comments to the proposal were submitted to Mr. Murphree, R-AERO-T.

e. Approval has been received on the abstract for the paper entitled, "The Influencing Factors in Satellite Orbital Decay and Life- time Analysis." A copy of the approval (MSFC Form 2818) along with the abstract has been submitted to Mr. Vaughan, R-AERO-Y, as a candidate paper to be presented at the AMS Meeting to be held at New Orleans on May 6-9, 1968. This paper will be co-authored by Mr. Revels and Mr. Fleischman.

f. A report comparing calculated lifetimes versus actual lifetimes for 54 satellites on'seven atmospheric models has been received from LMSC. These comparisons along with additional data being investigated by LMSC will be incorporated into a NASA Dl X. g. Letters have been written to various stage contractors informing them of future deliveries of magnetic tapes containing various tracking information, look angles, elevation, slant range, etc. This information is being supplied for the contractors to evaluate their systems after the flights. Information on magnetic tapes will be compared with similar information from the post-flight trajectory. Mr. Olen Ely, R-ASTR-IR, requested R-AERO-FT to supply this information as a part of the tracking and connnunications studies being performed for R-AERO-FT by both CCSD (Saturn IB) and TBC (Saturn V).

D. Flight Evaluation Branch

1. Saturn IB

Acoustic Data: Computation Laboratory has completed reduction of all telemetered flight acoustic data on the Acoustic Analyzer. The data, digitized and plotted on the SC-4020 plotter, include output of the 113 octave band filters and sound pressure levels in dB/Hz.

2. SaturnV

a. General

(1) S-IC Stage Engine Alignment

TBC-Huntsville has asked R-AERO-FF to concur with TBC-Michoud thrust alignment data for the Saturn V S-IC2, S-IC3, and S-IC4 vehicles. NASA data for the same stages were requested in a memo dated June 8, 1967, from Mr. McNair to Mr. McCool, R-P&VE-X. In response to this memo, Mr. Dale Strider of R-P&VE-VSL verbally told R-AERO-FF that R-P&VE does not have all of the information and, since the individual contributions of engine, actuator and stage to the total engine misalignments are required, the data should be obtained from R-QUAL, R-ASTR and R-P&VE, respectively. Mr. Jim Pierce, R-QUAL-AMR, verbally agreed to write a memo which either verifies TBC's SIC2 engine contribution data or contains the correct S-IC2 engine contribution data. Mr. Pierce is not willing to make a statement about the data for S-IC3 and subsequent stages at the present time. R-AERO-FF has not received an answer to these requests .

(2) Emergency Detection System

Memo R-AERO-FF-74-67, dated September 14, 1967,on the subject of loss of hydraulics at first and second S-IVB ignition was supplied to I-MO-MGR. The attitude and attitude rate buildups were shown based upon a 4.37 degree engine equilibrium position as determined by R-ASTR. (3) Post-Flight Processed IU Telemetered Data

R-AERO-FFA has published two memos describing the IU data tapes which will be generated and distributed to PDRD requestors after each Saturn V flight. The memos include lists of measurements that will be contained on the tapes and specify the period of flight and associated sample rates. The two tapes are designated "IU control parameter collation tape" and "IU miscellaneous parameter collation tape." Specific information concerning the individual tapes can be found in memo R-AERO-FF-60-67, "Saturn V Instrument Unit Control Param- eters Collation Tapes," dated August 14, 1967, and memo R-AERO-FF-63-67, "Saturn V Instrument Unit Miscellaneous Parameter Collation Tapes," dated August 17, 1967.

The "S-IC Control Parameters Conditioned Data Tapes," which will be available 10 days after launch, will supersede the IU control parameter data tape. The format and related information are contained in memo R-AERO-FF-59-67, "S-IC Control Parameters Conditioned Data Tape," dated August 14, 1967.

(1) Insertion Tracking

It now appears that there will be no ship C-band radar to support the AS-501 mission. The radars onboard the tracking ships are incapable of tracking because of rust, etc. Therefore, a study was performed to determine what effect the loss of this data would have on the determination of the post-flight parking orbit trajectory. The results of this study, documented in memorandum R-AERO-FF-75-67, indicate that it is important to have tracking data as soon after insertion as possible. Insertion tracking is very desirable, if not essential, for an accurate determination of the orbital trajectory. It is possible to make this determination without tracking data at insertion, but the accuracy of the orbital parameters is significantly degraded. This study also confirmed that less accurate tracking data fairly close to insertion can be very helpful in the determination of orbital param- e ters . (2) Pad Fallback

TBC special study SSR-147 "Pad Fallback Study for Mission AS-501" was distributed by memo R-AERO-FF-72-67, dated September 14, 1967. The effects of single and dual engipe failures and single actuator hardover failures on tower collision, holddown arm interference, and pad fallback are shown. These results may be used to assess the requirements for ground-commanded near-pad abort. Abort and Alternate Mission

A new scope was defined for the AS-503 and subsequent vehicle abort and alternate mission analyses. The scope includes the requirements for the preparation of a document covering Saturn V Launch Vehicle malfunctioned flight envelopes for S-IC single and dual engine out; for S-I1 stage without second plane separation, without LES jettison, with single and dual engine out, with propellant utilization (PU) valve failure, with guidance accelerometer failure, with no ignition, and with total propulsion shutdown; and for the S-IVB stage with early engine cutoff, with PU valve failure, with overspeed, and with guidance accelerometer failure.

A study is being conducted by R-P&VE-PP to define the approximate times of flight when an S-IC or S-I1 dual engine failure would result in shutdown of the remaining engines on the stage.

Propulsion sys tern simulations for the various failure cases were requested from R-P&VE-PP for AS-504 and subsequent Saturn V vehicles. The cases requested were S-IC and S-I1 stage single engine outs, S-I1 and S-IVB stage PU valve failures and S-IVB stage extended first burns. The other failures mentioned in the scope will be simulated from these cases.

3. Apollo Applications

a. Data Compression

A research of methods to compress data from long duration space flights was made. As a result, a reasonably simple technique for accomplishing this compression appears to be valid for steady state conditions. This method curve fits a sample of data (from ti to tn, consisting of N data points). Using the coefficients calculated from the curve fit a projection is made to points beyond tn. The projection is terminated when observed data exceeds a certain tolerance band placed on the curve fit and projected data. Compressed data to represent this segment of observed data consist of a few data points as calculated from the curve fit and its projection. No other data are retained.

To establish tolerance bands, it is necessary to calculate a standard deviation (o) of the observed data (X) between ti and tn. X. = observed data 1

X: = calculated data 1 N = number of data points.

The tolerance bands are established by using some multiple (a) of 0. The projection of the curve fit will terminate at the point where M number of consecutive observed data points are outside of the tolerance band (a . a) and are on the same side of the projection. This condition constitutes the need for generating a new curve fit and projection.

This compression technique has been tested on actual flight data. The results of the technique are encouraging; however, as may be expected, the degree of the polynomial curve fit, the multiple (a) of a, and other controlling variables have considerable influence on the degree of compression attainable. To properly use this technique, more testing on actual flight data will be needed to gain experience and knowledge of the relationship of the controlling variables with compression degree.

The special staff and board meeting scheduled for August to discuss FEWG-Payload was cancelled. It has not yet been re-scheduled.

A major concern of the FEWG-Payload staff is the criteria for selection of engineering measurements for the first cluster configuration. The request for this criteria was submitted by Mr. Powell (R-ASTR) as a guide to help him determine some criteria for this selection from the evaluation view point.

A special meeting was held Tuesday, September 12 (all senior representatives were present) to discuss (1) AAP schedule, (2) final review of AAP Payload Evaluation Plan, (3) engineering measurement selection criteria and (4) payload integration contractor activities. The majority of the time was spent on item number 3. After some discussion concerning this item, it was decided that a smaller group would meet on September 14 to come to some definite conclusion for this selection criteria. 4. Contracts

a. Saturn Q Systems (TBC/Huntsville)

(1) Post-Flight Trajectory

Considerable effort has been spent preparing TBC to assume the responsibility of establishing the post-flight trajectory on Saturn V vehicles. TBC has converted all of the programs from the IBM-7094 to their System 360. TBC has just completed a dry run under simulated conditions to produce a quick-look (48 hour) trajectory. This was done assuming there was no telemetered guidance data available. The dry run, which went well, gave the personnel involved some excellent experience. They realize that they still need to know a lot more about the capabilities and limitations of the programs. A dry run on the intermediate (7-day) and final (14-day) trajectories is planned for the very near future. TBC will do a parallel effort with MSFC on AS-501 and will assume the entire responsibility by AS-504.

(2) Post-Flight Clustered Engine Analysis

Using the Trajectory Application Method (TAM), TBC completed an analysis of the propulsion system performance for a hypothetical S-IB stage. The results of the analysis were very good. Since this analysis was performed using ideal data, a more realistic evaluation using actual flight data will be made as the next step in TBC's preparation for the S-IC stage clustered engine analysis.

A hypothetical S-IC stage flight was furnished TBC for checkout of their Propulsion Evaluation Program (PEP). This program is unique since it uses telemetered vehicle attitudes and engine gimbal angles with the components of vehicle inertial acceleration (from tracking) to determine the individual engine thrust errors. TBC has had a considerable amount of difficulty trying to get the program to give good results. The problem seems to be one of statistics associated with accuracy of telemetry and tracking.

b. S-I1 Stage (NAAISD)

Pos t-Flight Propulsion Simulation

SD has completed a practice flight evaluation of the S-I1 stage propulsion system performance using their 6D flight simulation program. The results of the analysis were good in that their program accepted the format on the various input tapes furnished by MSFC. The formats of these tapes are the same as those to be furnished for the AS-501 flight evaluation. c. Mission Support

(1) Strapdown Guidance (Nortronics)

Nortronics/Huntsville has begun work on the SD-53 flight evaluation task. No tangible results have yet been received. There was a month's delay because of the uncertainty of who would actually perform the task, Nortronics or Lockheed.

(2) Guidance and Tracker Evaluation (GATE) (Lockheed)

Lockheed under the mission support effort has been analyzing and verifying the main pos t-flight trajectory program (GATE). This program makes a composite fit of all the tracking data and estimates a set of guidance and tracker error coefficients. By applying these guidance error coefficients back to the telemetered guidance velocity data, a "best estimate" trajectory will result. The program has been verified and is being documented by IMSC. The final draft of "Manual For the GATE Program" has been received for review and will be published soon.

5. General

a. Powered Flight Trajectory Techniques

A paper entitled "Powered Flight Trajectory Determina- tion Techniques as Applied to Saturn V Vehicles" was presented at the AIM Guidance, Control and Flight Dynamics Conference in Huntsville on August 14, 1967. The paper was well received and many questions and inquiries have been answered concerning it.

b. Kalman Filter Studies

To more efficiently use our existing powered flight trajectory determination techniques and to develop improved techniques, a better understanding of the Kalman filter is necessary. Thirty-three proposals were received in response to an RFQ entitled, "Studies in the Theory and Application of Kalman Filtering." The technical evaluation of these proposals was documented in memorandum R-AERO-FF-76-67. Five of the proposals were technically acceptable.

c. Automatic Guidance Data Edit

In the past, a considerable amount of work has been in processing minor loop telemetry data. Techniques have been formulated to automatically edit the telemetry, eliminate noise or wild data points, and interpolate the data to a common time at even time intervals. The minor loop parameters consist of X, Y, 2 fine gimbal measurements; pitch, yaw, roll ladder outputs; and accumulated pulse outputs of the guidance accelerometers. Provisions have been included in the program to adjust for cycling of the onboard counters and necessary scaling to convert the outputs to engineering units.

Since each parameter has a time associated with it, an interpolation procedure was included to relate all parameters to a common time. This cmon time will be in terms of Range Time at even time intervals to be compatible with other post-flight data. The program has been checked out using data tape generated by the laboratory.

PUBLICATIONS

1. Hayes, Russell M., "An Algorithm for the Determination of the Definiteness of a Real Square Matrix," NASA TM X-53644, August 8, 1967, Unclassified.

2. Aerospace Environment Division, "Recent Contributions in Dynamical and Statistical Meteorology to Aerospace Vehicle Problems," NASA TM X-53649, August 24, 1967, Unclassified.

3. Liu, Frank C., "On Dynamics of Two Cable-Connected Space Stations," NASA TM X-53650, August 28, 1967, Unclassified.

4. Baker, C. D., J. C. Blair, and W. E. Causey, "Some Flight Mechanics Considerations for the Voyager Mission," NASA IM X-53654, September 8, 1967, Unclassified.

5. Vaughn, 0. H., "A Proposed Hypothetical Exploration Mission in the Flamsteed Crater Region of the Moon," NASA TM X-53655, September 14, 1967, Unclassified.

6. Glasgow, R. M. , "Static Aerodynamic Characteristics of the Aborted Apollo-Saturn V Vehicle," NASA IM X-53656, September 22, 1967, Unclassified.

7. Nunley, B. W., "Static Aerodynamic Characteristics of the Apollo Saturn IB Vehicle," NASA 'IN X-53657, September 25, 1967, Uncl.

8. Vaughn, 0. H., "Lunar Environment: Design Criteria Models for Use in Lunar Surface Mobility Studies," NASA IM X-53661, September 28, 1967, Unclassified.

9. Wood, G. A., "Insertion Velocities Required to Enter Various Orbits About the Planet Mars," Aero-Astrodynamics Internal Note #6-67, August 8, 1967, Unclassified. APPROVAL

~epudDirector, Aero-Astrodynamics Laboratory

&-n. 4*b-4 E. D. Geissler Director, Aero-Astrodynamics Laboratory

DISTRIBUTION

R-AERO-DIR PAO, Mr. Kurtz Dr. Geissler Mr. Jean R-DIR, Mr. Weidner Mr. Butler MS-H, Miss Jerrell (3) R-AERO-R Mr. Bean (4) I-V-P, Mr. Price Mrs. Hightower

R-AERO-P (8) R-AERO-D (16) R-AERO-A (20) R-AERO-G (6) R-AERO-Y (8) R-AERO-F (8) R-AERO-X (4)

R-AERO-T Mr. Murphree Mr. Cumings Mr. Dickey Dr. Heybey Mr. Jandebeur Dr. Liu Dr. Krause Mr. Nathan Mr. Few