DOCSLIB.ORG

NASA Technical Paper 3537 Flight Test of the X-29A at High Angle Of

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
NASA Technical Paper 3537 Flight Test of the X-29A at High Angle Of NASA Technical Paper 3537 1995 Flight Test of the X-29A at High Angle of Attack: Flight Dynamics and Controls Jeffrey E. Bauer Robert Clarke John J. Burken Dryden Flight Research Center Edwards, California National Aeronautics and Space Administration Office of Management Scientific and Technical Information Program CONTENTS ABSTRACT ........................................................................ 1 INTRODUCTION .................................................................... 1 AIRCRAFT DESCRIPTION ........................................................... 1 Flight Control System .............................................................. 2 Mode Logic ................................................................... 2 Design Requirements ............................................................ 2 Design Technique .............................................................. 3 Longitudinal Control Law Design .................................................. 3 Roll and Yaw Control Law Design ................................................. 4 Pilot-Selectable Gain ............................................................ 4 Flow Angle and Pitot-Static Measurement Systems .................................... 5 Simulation ....................................................................... 5 TEST AND PROCEDURES ............................................................ 6 Envelope Expansion ............................................................... 6 Piloted Simulation and Updates ...................................................... 6 RESULTS AND DISCUSSION ......................................................... 7 Flight Characteristics and Correlation With Preflight Predictions ............................ 7 Wing Rock and Lateral Control Power .............................................. 7 Pitching Moment Characteristics ................................................... 8 Yaw Asymmetries .............................................................. 9 Flying Qualities Research .......................................................... 10 Structural Dynamics Interaction With the Flight Control System ........................... 13 SUMMARY OF RESULTS ........................................................... 14 APPENDIX A--LINEAR MODELS .................................................... 16 APPENDIX B--PILOT COMMENTS .................................................. 17 NOMENCLATURE ................................................................. 22 REFERENCES ..................................................................... 23 iii P_ PAGE .BL,_tI'K NOT FIL_',,_E';..' TABLES 1 The X-29A no. 2 geometry and mass characteristics .................................... 25 2 High-angle-of-attack design guidelines .............................................. 26 3 Longitudinal and lateral stick characteristics .......................................... 26 4 Matrix of test points for flying qualities research ...................................... 26 A- 1 An s-plane description of continuous dynamic elements ................................ 27 iv FIGURES 1 The X-29A no. 2 test airplane ..................................................... 29 2 The X-29A no. 2 cockpit displays .................................................. 30 3 The X-29A no. 2 spin chute assembly ............................................... 31 4 The X-29A longitudinal control system ............................................. 32 5 The X-29A lateral-directional control system ......................................... 32 6 Time histories of the angle-of-attack redundancy management failure from flight 27 .......... 33 7 The X-29A high-angle-of-attack envelope ........................................... 34 8 Drop-model wing rock with a 0.88 deg/(deg/sec) roll damping gain ....................... 35 9 Wing drop time history .......................................................... 36 10 Wing rock time history .......................................................... 40 11 Magnitude of bank angle oscillation as a function of angle of attack during wing rock ......... 41 12 Open-loop dutch roll pole locations ................................................. 41 13 Pitch rate comparison ............................................................ 42 14 Simulation match to flight data for pitching maneuver .................................. 43 15 Surface rates during pitching steps ................................................. 45 16 Minimum nosedown aerodynamic pitching moment ................................... 47 17 The X-29A high-angle-of-attack lateral--directional flight control system with variable gains highlighted ............................................................... 47 18 Stability axis roll rate (at 200 kn and an altitude of 20,000 ft) as a function of angle of attack... 48 19 Body axis yaw rate required (at 200 kn and an altitude of 20,000 ft) for coordination of stability axis roll rate of figure 18 .................................................. 48 20 Effect of sideslip on roll coordination for a typical bank angle maneuver ................... 49 21 Roll coordination data (all data represented as if roll were negative (to the left)) ............ 51 V 22 Maximum rudder deflection during 180 ° roll captures at 200 kn equivalent airspeed .......... 52 23 Maximum aileron deflection during 180 ° roll captures at 200 kn equivalent airspeed .......... 53 24 Angle of sideslip buildup during position limiting ..................................... 54 25 Effects of filtering on lateral acceleration components ................................. 55 26 Cockpit lateral acceleration at roll initiation .......................................... 56 27 Largest cockpit lateral acceleration components during maneuver ......................... 56 28 Flight data fit to determine roll mode time constant .................................... 57 29 Roll mode time constant as a function of stability axis roll rate at a 30 ° angle of attack ........ 58 30 Proposed criteria for a 30 ° angle of attack ........................................... 58 31 Roll rate gyroscope signal power spectral density ...................................... 59 A-1 Linear matrices ................................................................. 60 A-2 Longitudinal control system ...................................................... 63 A-3 Lateral--directional control system .................................................. 63 vi ABSTRACT has several advantages in this flight regime. 5' 6 The configuration was designed to be departure resistant and to maintain significant roll control at high angles of The NASA Dryden Flight Research Center has flight tested two X-29A aircraft at low and high angles of attack. To further investigate the potential of a forward- swept wing at high angles of attack, the X-29A military attack. The high-angle-of-attack tests evaluate the fea- utility and agility test program was initiated in 1986 as sibility of integrated X-29A technologies. More specif- a follow-on to the low-angle-of-attack program, l' 2 7-10 ic objectives focus on evaluating the high-angle-of- This paper provides results from the envelope expan- attack flying qualities, defining multiaxis controllabili- ty limits, and determining the maximum pitch-pointing sion and handling qualities testing at intermediate angles of attack. Topics include envelope expansion, capability. A pilot-selectable gain system allows exam- ination of tradeoffs in airplane stability and maneuver- flight test techniques, and flight test results. Compari- ability. Basic fighter maneuvers provide qualitative sons of the flight test results to the predictions are made where appropriate. evaluation. Bank-angle captures permit qualitative data analysis. This paper discusses the design goals and approach AIRCRAFT DESCRIPTION for high-angle-of-attack control laws and provides results from the envelope expansion and handling qual- The X-29A aircraft is a single-seat, single-engine ities testing at intermediate angles of attack. Compari- fighter class aircraft (fig. 1). An F-5 forebody is used sons of the flight test results to the predictions are made forward of the pilot station, and F-16 integrated servo- where appropriate. The pitch rate command structure actuators are used for all except the strake actuators. of the longitudinal control system is shown to be a val- The cockpit has conventional dial display gauges id design for high-angle-of-attack control laws. Flight (fig 2). No cathode-ray-tube screens or head-up dis- test results show that wing rock amplitude was over- plays are used. predicted and aileron and rudder effectivenesses were The wing has a thin, 4.9 percent-thick streamwise underpredicted. Flight tests show the X-29A airplane supercritical airfoil section with a 29.27 ° forward to be controllable in all axes, with no nose wandering, sweep along the leading edge and a -33.73 ° quarter- up to 40 ° angle of attack. chord sweep. The wing structure includes aeroelastical- ly tailored graphite-epoxy covers to help provide the INTRODUCTION stiffness needed to overcome the torsional divergence problems associated with forward-swept wings. The The NASA Dryden Flight Research Center (NASA wing is relatively simple, employs full-span trailing- Dryden) X-29A program was structured to test the edge flaps, and does not use leading-edge devices. X-29A no. 1 airplane at low angles of attack and the These double-hinged flaps also provide discrete vari- able camber. no.
Load more

Recommended publications
  • The Role and the Use of the Rudder
    of us have ignorantly followed sim- The Role and the Use plistic rules. When the aircraft is in equilibrium flight, it is not accelerating in any di- of the Rudder rection or about any axis. It is only then that the attitude indicators are reli- able. You know how long it takes for Daniel L. Johnson, Different parts of the aircraft may the airspeed indicator to catch up with reporter be in quite different air. This causes a change in angle of attack. Such lags uncommanded pitch, yaw, and roll are present in all indicators, reflecting changes, to which we respond swiftly time needed for the aircraft to come "It is interesting that we, as student with control movements. The thermal into equilibrium after any change in a pilots, are given several hard and fast tries to spit you out. force or moment. rules, which, as we venture out on our There are two situations in which The primary purpose of the vertical own, arent so hard and fast after all." this is especially important: circling in stabilizer is to achieve yaw, or weath- — RBick a thermal and landing in turbulence. ercock, stability. When the fuselage is We also learn that we cannot correct yawed, the vertical stabilizer creates a - Author caveat: I have done my best to every wrinkle in the air, and we must restoring moment that realigns it with be faithful to the science while clarifying learn to "fly attitude," knowing when the airflow, in the same way a weather- control use. But like all inexpert writing, to let the little wrinkles average them- vane works.
    [Show full text]
  • How to Spin Unintentionally
    so there's margin for roll correction in either direction. The yaw string in that moment, due to turbulence or normal awkwardness, will DANIEL L.JOHNSON wobble back and forth between a slip and a skid, "centered" on the average. But the wing does not care about its average air- flow; it cares about each moment's flow. How to Spin "The middle of the air" (metaphori- cally) is the safe place to be, but the centered yaw string, in a steep turn, is at the border between a skid and a slip, Unintentionally so a (literally) centered yaw string is (metaphorically) "on the edge of the air" vector pointing straight down? (centered Try to stay in the middle of the air. in a slow turn. Humorously, an actually- Do not yo near the edges of it. ball) o o J middle yaw string is metaphorically at • Does it mean drag is balanced be- The edges of the air can be recognized the brink of the cliff. by the appearance of ground, tween the wings? Thus, we should prefer the yaw string buildings, sea, trees, • Does it mean that each wing is to flop between center and our high side, and interstellar space. about equally far from stalling? not crossing the center to the low side. It is much more difficult to fly there. These things are easy to synchronize "Attention," as we explained last - unknown wit when nearly level (up to a 30-degree month, acts through 'built-in brain net- bank). But as the turn becomes steeper, works that can be improved with training hesis: Most gliding fatal accidents it becomes impossible to meet all four of and practice.
    [Show full text]
  • Speed, Angle of Bank and Yaw String
    Speed, Angle of Bank and Yaw String. Over the years I have been coaching it surprises me how few pilots are able to fly gliders in circles, in a manner that is necessary to milk the most out of thermals. Hopefully if you put into practice what I will mention in the next few paragraphs you will be able to take a major step forward in your flying performance. Much is spoken of the importance when thermalling of maintaining a constant angle of bank and speed. Without accuracy your circle will shift erratically and thus any deliberate modification of the circle will be negated by the otherwise inaccurate flying. However how accurate is accurate? Below is a chart giving angle of bank, on the left, against speed in knots along the top. The figures given in the grid are the diameter of the circle. E.g. a speed of 50 knots and 45° angle of bank will give a circle of 129 meters. 40 45 50 55 60 30° 145 184 227 275 328 35° 112 152 188 227 270 40° 100 126 156 189 226 45° 82 105129 156186 50° 70 89 110 133159 55° 59 74 92 111132 Now let us consider a pilot with an angle of bank of 45° and speed from 45 Knots giving a circle of 105 meters diameter. He maintains this for half a turn, and follows it by a further half a turn of 40° at 50 Knots. The very small change in speed and angle of bank but giving 156-metre diameter turn, for the next half circle, It can now be seen that these small changes of speed and angles of bank will move the centre of the original circle by around 25%.
    [Show full text]
  • Aircraft General Knowledge
    Part-FCL Question Bank SPL Acc. (EU) 1178/2011 and AMC FCL.115, .120, 210, .215 (Excerpt) 80 – Aircraft General Knowledge 80 Aircraft General Knowledge ECQB-PPL - SPL Publisher: EDUCADEMY GmbH [email protected] COPYRIGHT Remark: All parts of this issue are protected by copyright laws. Commercial use, also part of it requires prior permission of the publisher. For any requests, please contact the publisher. Please note that this excerpt contains only 75% of the total question bank content. Examinations may also contain questions not covered by this issue. Revision & Quality Assurance Within the process of continuous revision and update of the international question bank for Private Pilots (ECQB-PPL), we always appreciate contribution of competent experts. If you are interested in co- operation, please contact us at [email protected]. If you have comments or suggestions for this question bank, please contact us at [email protected]. v2020.2 2 80 Aircraft General Knowledge ECQB-PPL - SPL 1 Which levers in a glider's cockpit are indicated by the colors red, blue and green? Levers for usage of ... (1,00 P.) gear, speed brakes and elevator trim tab. speed brakes, cable release and elevator trim. speed brakes, cabin hood lock and gear. cabin hood release, speed brakes, elevator trim. 2 The thickness of the wing is defined as the distance between the lower and the upper side of the wing at the... (1,00 P.) thinnest part of the wing. most inner part of the wing. thickest part of the wing. most outer part of the wing. 3 How is referred to a tubular steel construction with a non self-supporting skin? (1,00 P.) Grid construction Honeycomb structure Monocoque construction Semi-monocoque construction.
    [Show full text]
  • TOTAL ENERGY COMPENSATION in PRACTICE by Rudolph Brozel ILEC Gmbh Bayreuth, Germany, September 1985 Edited by Thomas Knauff, & Dave Nadler April, 2002
    TOTAL ENERGY COMPENSATION IN PRACTICE by Rudolph Brozel ILEC GmbH Bayreuth, Germany, September 1985 Edited by Thomas Knauff, & Dave Nadler April, 2002 This article is copyright protected © ILEC GmbH, all rights reserved. Reproduction with the approval of ILEC GmbH only. FORWARD Rudolf Brozel and Juergen Schindler founded ILEC in 1981. Rudolf Brozel was the original designer of ILEC variometer systems and total energy probes. Sadly, Rudolph Brozel passed away in 1998. ILEC instruments and probes are the result of extensive testing over many years. More than 6,000 pilots around the world now use ILEC total energy probes. ILEC variometers are the variometer of choice of many pilots, for both competition and club use. Current ILEC variometers include the SC7 basic variometer, the SB9 backup variometer, and the SN10 flight computer. INTRODUCTION The following article is a summary of conclusions drawn from theoretical work over several years, including wind tunnel experiments and in-flight measurements. This research helps to explain the differences between the real response of a total energy variometer and what a soaring pilot would prefer, or the ideal behaviour. This article will help glider pilots better understand the response of the variometer, and also aid in improving an existing system. You will understand the semi-technical information better after you read the following article the second or third time. THE INFLUENCE OF ACCELERATION ON THE SINK RATE OF A SAILPLANE AND ON THE INDICATION OF THE VARIOMETER. Astute pilots may have noticed when they perform a normal pull-up manoeuvre, as they might to enter a thermal; the TE (total energy) variometer first indicates a down reading, whereas the non-compensated variometer would rapidly go to the positive stop.
    [Show full text]
  • The Yaw String Method of Tinkering with Sailplane
    THE YAW STRING METHOD OF poise maneuv€rs. But I hated the way it thermaled. I was too accustomed to pulling back on the stick of my Libelle TINKERING WITH SAILPLANE until iust above the stall and corkscrewing around near the core of a thermal. t could not come close to doint this WING DESIGN in PC2. To get maximum per{ormance takes an entirely different thermaling technique, to which l'm not sure I By Paul N. Chase want to adapt. I think a r€lated problem occurs during landing round-our the sailplane appears to sink into the Submitted io the SSA office. runhay abruptly wrLh flving speed )rill remaining. even while incrcasing pitch attitude. SUMMARY t he wing on PC2 appears to have a -harp rncrease in I know you won't believe this, but I actually fine tuned drag starting four to five knots above the stall with no my Ventus B wing to my style of flying by Putting turbu- other indications in the airframe. The sailplane sounds lator tape at different test positions on the uPPer surface alrighL feels alight and contiols alrightr it just starts of the outer 12 feet of one wing and recording the amount sinking at a rapidly increasing rate as stall is apProached. of good and bad yaw at low and hith airspeeds. When I I have houble judging where this increased sink rate found the desired compromise chordwise position, I put starts when I am in a steep turn trying to center a small tape on the entire win8.
    [Show full text]
  • SSA Webinar Handout Intermediate
    SSA Webinar Handout Intermediate/Advanced Thermaling Techniques April 14, 2020 Glider Pilot Vocabulary Climb Rate: The rate at which an aircraft rises relative to the ground. Core: In the context of this discussion, the strongest part of a thermal at a given altitude or one of multiple thermals in a close group of thermals at a given altitude. Glider: Heavier-than-air aircraft with no propulsion system. Lag: In the context of this discussion, the delay between a change in the vertical speed of the air at the glider’s location and the response of the vario indicating this change. Lift (noun): For a glider pilot, this term can have one of two meanings. First, “lift” can mean one of the basic aerodynamic forces generated by the motion of the wing through the air. In simple terms, in normal straight-and-level flight, it’s the main force opposing weight. In the context of this webinar, however, most of the time the term “lift” is used, it simply means air that is rising relative to the ground. “Natural” sink rate: The rate at which an aircraft would descend relative to the ground if in air that has no vertical motion relative to the ground. Sailplane: A glider with a fixed wing, a tail (usually), and movable control surfaces, typically controlled by stick and rudder by a pilot seated in a cockpit. Often used interchangeably with the term “glider” by those who fly sailplanes. Hang gliders and paragliders are gliders – but aren’t sailplanes. Surge: In the context of this discussion, a brief (few to several seconds) shot of stronger lift (i.e., air moving upward at a higher rate) within a given thermal.
    [Show full text]
  • F/A-18A-D Flight Control Computer OFP Versions 10.6.1 and 10.7
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 5-2004 F/A-18A-D Flight Control Computer OFP Versions 10.6.1 and 10.7 Developmental Flight Testing: Out-of-Controlled Flight Test Program Yields Reduced Falling Leaf Departure Susceptibility and Enhanced Aircraft Maneuverability Eric John Mitchell University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Part of the Aerospace Engineering Commons Recommended Citation Mitchell, Eric John, "F/A-18A-D Flight Control Computer OFP Versions 10.6.1 and 10.7 Developmental Flight Testing: Out-of-Controlled Flight Test Program Yields Reduced Falling Leaf Departure Susceptibility and Enhanced Aircraft Maneuverability. " Master's Thesis, University of Tennessee, 2004. https://trace.tennessee.edu/utk_gradthes/2372 This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a thesis written by Eric John Mitchell entitled "F/A-18A-D Flight Control Computer OFP Versions 10.6.1 and 10.7 Developmental Flight Testing: Out-of-Controlled Flight Test Program Yields Reduced Falling Leaf Departure Susceptibility and Enhanced Aircraft Maneuverability." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Master of Science, with a major in Aviation Systems.
    [Show full text]
  • Glider Handbook, Chapter 4: Flight Instruments
    Chapter 4 Flight Instruments Introduction Flight instruments in the glider cockpit provide information regarding the glider’s direction, altitude, airspeed, and performance. The categories include pitot-static, magnetic, gyroscopic, electrical, electronic, and self-contained. This categorization includes instruments that are sensitive to gravity (G-loading) and centrifugal forces. Instruments can be a basic set used typically in training aircraft or a more advanced set used in the high performance sailplane for cross- country and competition flying. To obtain basic introductory information about common aircraft instruments, please refer to the Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25). Instruments displaying airspeed, altitude, and vertical speed are part of the pitot-static system. Heading instruments display magnetic direction by sensing the earth’s magnetic field. Performance instruments, using gyroscopic principles, display the aircraft attitude, heading, and rates of turn. Unique to the glider cockpit is the variometer, which is part of the pitot-static system. Electronic instruments using computer and global positioning system (GPS) technology provide pilots with moving map displays, electronic airspeed and altitude, air mass conditions, and other functions relative to flight management. Examples of self-contained instruments and indicators that are useful to the pilot include the yaw string, inclinometer, and outside air temperature gauge (OAT). 4-1 Pitot-Static Instruments entering. Increasing the airspeed of the glider causes the force exerted by the oncoming air to rise. More air is able to There are two major divisions in the pitot-static system: push its way into the diaphragm and the pressure within the 1. Impact air pressure due to forward motion (flight) diaphragm increases.
    [Show full text]
  • BPPP Flight Instructor Standardization Manual
    BPPP Instructor Standards Manual ABS Air Safety Foundation P.O. Box 12888 Wichita, Kansas USA 67277 www.bonanza.org Revision 8 December 2012 Revision 8 December 2012 INTRODUCTION AUTHORITY The BPPP Instructor Standards Manual (Manual) is published under the authority of the Beechcraft Pilot Proficiency Program, Inc. (BPPP), a wholly owned subsidiary of the American Bonanza Society Air Safety Foundation. PURPOSE The BPPP Instructor Standards Manual is provided to BPPP designated flight instructors for their use when conducting flight training on behalf of BPPP. It also serves as a text in the ABS Flight Instructor Academy and as a resource for Academy graduates. The Manual contains limitations, best practices and maneuver elements intended to promote procedural standardization among BPPP instructors when conveying to the BPPP clinic pilot the knowledge, flying skills and confidence to operate their airplane safely and efficiently. The material in this manual is intended solely for the use of BPPP administrators and instructors when conducting flight training within the scope of the BPPP Program. ISSUANCE Initial issuance of a BPPP Instructor Standards Manual is free of charge to flight instructors in the BPPP program. Replacement of the Manual is made at a cost to the instructor as determined at the time of replacement. The Manual remains the exclusive property of BPPP and may not be copied or transferred in whole or in part to any other person or entity without the express permission of the BPPP Director of Training and Instructor Standardization. At the time the instructor is no longer participating in the BPPP flight training program, the Manual must be returned to BPPP.
    [Show full text]
  • General Purpose GPS Navigation Module
    Project: FJL – GPS1 General Purpose GPS Navigation Module MQP Ver. 1.9 3/4/10 Nicholas Granata – Cappabianca [email protected] WPI box number 724 ECE box number 7 1 Table of Contents Table of Contents .......................................................................................................................................... 2 1.0 Introduction ............................................................................................................................................. 4 1.2 Project Statement ................................................................................................................................... 4 1.3 Summary ................................................................................................................................................. 5 2.0 Introduction ............................................................................................................................................. 6 2.1 Soaring ..................................................................................................................................................... 6 2.1.1 Glider Lift ............................................................................................................................................ 10 2.1.2 Glider Performance ............................................................................................................................ 11 2.2 GPS.......................................................................................................................................................
    [Show full text]
  • Flying Light Twins Safely
    Flying Light Twins Safely Note: The graphics and some of the material in this document have been modified from the original printed version. Introduction The major difference between flying a light twin and a single-engine airplane is knowing how to manage the flight if one engine loses power. Safe flight with one engine inoperative (OEI) requires an understanding of the basic aerodynamics involved as well as proficiency in single-engine flight. This booklet deals extensively with the numerous aspects of OEI flight. You must remember, however, not to place undue emphasis on mastery of OEI flight as the sole key to flying light twins safely. The Normal Takeoff For normal takeoff planning, use the manufacturer’s recommended rotation speed (Vr) or lift-off speed (Vlof). If no such speeds are published, use a minimum of minimum control speed (Vmc) plus 5 knots for Vr. As a rule, light twins should not be airborne before reaching Vmc. After lift-off, the next consideration is to gain altitude as rapidly as practicable. After leaving the ground, altitude gain is more important than achieving an en route climb airspeed. Allow the airplane to accelerate in a shallow climb to attain Vy, the best rate of climb speed when both engines are operating. Maintain Vy until a safe single- engine maneuvering altitude, typically at least 400 feet above ground level (AGL), has been achieved. (If Vy would result in a pitch attitude of more than 15 degrees, consider limiting the initial pitch attitude to 15 degrees to minimize control difficulty if an engine is lost.) A transition to an en route climb can then be made as climb power is set.
    [Show full text]