DOCSLIB.ORG

Development of Selected Advanced Aerodynamics and Active Control Concepts for Commercial Transport Aircraft

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Development of Selected Advanced Aerodynamics and Active Control Concepts for Commercial Transport Aircraft https://ntrs.nasa.gov/search.jsp?R=19870008226 2020-03-20T12:35:06+00:00Z - NASA Contractor Report* 378 1 Development of Selected Advanced Aerodynamics and Active Control Concepts for Commercial Transport Aircraft CONTRACT NAS1-15327 FEBRUARY 1984 NASA Contractor Report 3781 Development of Selected Advanced Aerodynamics and Active Control Concepts for Commercial Transport Aircraft A. B. Taylor M cDonne 11 Douglas Corporation Long Beach, California Prepared for Langley Research Center under Contract NAS1-15327 National Aeronautics and Space Administration Scientific and Technical Information Office 1984 FOREWORD This document is the summary report of the work carried out by Douglas Aircraft Company under Contract NAS1-15327, which was part of the NASA Energy Efficient Transport (EET) project. The EET is one of several projects contained in the Aircraft Energy Efficiency (ACEE) activity. Douglas-sponsored work was done in association with EET, and appropriate summaries of the results are included in the report. The NASA EET Project Manager was Mr. R. V. Hood of Langley Research Center. The Technical Monitor was Mr. T. G. Gainer; Mr. D. W. Bartlett was coordinator of aerodynamics research. The on-site NASA representative was Mr. J. R. Tulinius. Many of the wind tunnel programs were conducted at Ames Research Center and some at Langley Research Center, and acknowledgment is given to the Directors and staffs for their assistance. Acknowledgment is also given to the Director and staff of Dryden Flight Test Center for their assistance during the flight evaluation activity. The key Douglas program personnel were: M. Klotzsche ACEE Project Manager A. B. Taylor EET Project Manager J. E. Donelson Long Duct Nacelle Aerodynamic Development Task W. A. Shirley Active Control Transport Development Task D. K. Steckel, J. A. Dahlin, P. A. Henne High-Aspect-Ratio Supercritical Wing - Cruise Speed Task W. R. Oliver, J. B. Allen High-Aspect-Ratio Supercritical Wing - High Lift Task Dr. C. A. Shollenberger Winglet Model Testing - Preflight Evaluation Task P. T. Sumida Winglet Flight Evaluation Task J. T. Callaghan Winglet Model Testing - Postflight Evaluation Task D. S. Retrum, N. S. Vrabel Program Financial and Schedule Control Task Throughout the program, notable contributions were received from the following Douglas personnel: J. G. Callaghan Aerodynamics J. T. Callaghan Aerodynamics J. D. Cadwell, J. C. Strong Aerodynamics Wind Tunnel Testing) iii CONTENTS Page INTRODUCTION .............................................................. 1 SYMBOLS .................................................................... 3 LONG-DUCT NACELLE AERODYNAMIC DEVELOPMENT ...................... 5 Results ................................................................... 6 Conclusions from the Long-Duct Nacelle Task ................................. 9 EXPERIMENTAL INVESTIGATION OF ELASTIC MODE CONTROL ON A MODEL OF A TRANSPORT AIRCRAFT ................................... 11 Program Approach ......................................................... 11 Results ................................................................... 14 Conclusions from the Elastic Mode Control Investigation ........................ 17 HIGH-ASPECT-RATIO SUPERCRITICAL WING TECHNOLOGY .................. 19 HIGH-ASPECT-RATIO SUPERCRITICAL WING AERODYNAMIC DEVELOPMENT .CRUISE SPEED ............................................ 21 Three-Dimensional Wing Configuration ....................................... 21 Three-Dimensional Test Results ............................................. 21 Two-Dimensional Test Configurations ........................................ 26 Two-Dimensional Test Results ............................................... 27 Conclusions from the Three-Dimensional Tests ................................ 29 Conclusions from the Two-Dimensional Tests .................................. 30 HIGH-ASPECT-RATIO SUPERCRITICAL WING AERODYNAMIC DEVELOPMENT .HIGH LIFT ................................................ 31 Test Configurations ........................................................ 31 Results of the Wide-Body Tests .............................................. 33 Results of the Narrow-Body Tests ............................................ 33 Conclusions from the High-Lift Tests ......................................... 36 WINGLET TECHNOLOGY DEVELOPMENT FOR DC-10 DERIVATIVES ........... 39 WINGLET MODEL TESTING AND ANALYSIS .PREFLIGHT EVALUATION ..... 43 High-speed Stability and Control Wind Tunnel Tests ........................... 43 ....... A9 Low-Speed Performance ana atamiity and Coilti-ol Wiiid Tunnel Tests ............ Ltu Subsonic Flutter Investigations .............................................. 46 Configuration Integration Effects ............................................ 47 Conclusions from the Winglet Preflight Investigation ........................... 47 WINGLET FLIGHT EVALUATION ............................................. 49 Winglet Design Configuration ............................................... 49 Design Analyses ........................................................... 50 Flight Program Approach ................................................... 51 Flight Test Program ....................................................... 52 V CONTENTS (Continued) Page BWL Test Configurations ................................................... 52 BWL Results .............................................................. 55 Cruise Performance ........................................................ 59 RSWL Test Configurations .................................................. 61 RSWL Results ............................................................. 63 Impact of Flight Evaluation Results on Operational Performance ................. 66 Conclusions from the Winglet Flight Evaluation ................................ 67 WINGLET MODEL TESTING .POSTFLIGHT EVALUATION .................... 69 Effectof Wing Trailing-Edge Modifications on the High-speed Stability and Control Characteristics of the DC-10 with Winglets ............................. 69 Low-Speed Tests of the DC-10 Aircraft with Winglet and Wing Modifications ...... 71 High-speed Tests of the DC-10 Aircraft with Winglet and Wing Modifications ...... 76 Conclusions from the Winglet Postflight Investigations ......................... 80 CONCLUDING REMARKS ..................................................... 83 Elastic Mode Control ....................................................... 83 High-Aspect-Ratio Supercritical Wing ........................................ 83 Winglet ................................................................... 84 REFERENCES ................................................................ 85 APPENDIX .WIND TUNNEL TESTING CONDUCTED .......................... 87 . ILLUSTRATIONS Figure Page 1 Comparison of Baseline and Revised LDN Model ........................... 5 LDN model ........................................................... 6 Effect of LDN Installation on Inboard Channel Pressures ................... 7 Pylon Sections Showing Baseline and Faired Shapes ........................ 8 Semispan Active Control Model ......................................... 12 Full-Span Active Model Control ......................................... 13 Block Diagram of Aileron Control Laws ................................... 13 Open and Closed-Loop Semispan Flutter Characteristics for the Zero Fuel Configuration .......................................... 14 9 Semispan Model Flutter Speed Versus Percent Fuel ........................ 15 10 Semispan Power Spectral Density of Midspan Bending Moment .............. 16 11 Flutter Damping Versus Velocity for the Full-Span Model ................... 17 12 Full-Span Power Spectral Density of Midspan Bending Moment ............. 18 13 ATMR .General Arrangement ......................................... 20 14 ATMR Wing Planform ................................................. 21 15 High-speed HASCW Model ............................................. 22 16 Clean Wing Drag-Rise Characteristics .................................... 23 17 Comparison of Wing Sectional Pressure Distributions ...................... 23 18 Nacelle Positions Tested ................................................ 24 19 Effect of Nacelle Longitudinal Position on Nacelle/Pylon Incremental Drag .... 24 20 Buffet Onset Boundary ................................................. 25 21 Tail Configurations Tested .............................................. 25 22 Effect of Horizontal Tail Configuration on Pitching Moment ................. 26 23 Drag Rise Performance of Thick Aftersection Airfoil with and without Wedge ................................................ 28 24 Drag Rise Performance of Modified Upper Surface Airfoil with and without Wedge ................................................ 29 25 Wide-Body HASCW High-Lift Model ..................................... 31 26 Narrow-Body High-Lift Model ........................................... 32 27 High-Lift Components Evaluated in Wide-Body Test Program ............... 32 28 Comparison of Narrow-Body and Wide-Body Landing Configuration Characteristics ........................................... 34 29 Effect of Reynolds Number on Narrow-Body Landing Configuration ................................................. 35 vii ILLUSTRATIONS (Continued) Figure Page 30 Comparison of Narrow-Body and Wide-Body Takeoff Configuration .......... 35 31 Comparison of Narrow-Body and Wide-Body Takeoff Lift-To-Drag Ratios ...........................................
Load more

Recommended publications
  • Helicopter Dynamics Concerning Retreating Blade Stall on a Coaxial Helicopter
    Helicopter Dynamics Concerning Retreating Blade Stall on a Coaxial Helicopter A project presented to The Faculty of the Department of Aerospace Engineering San José State University In partial fulfillment of the requirements for the degree Master of Science in Aerospace Engineering by Aaron Ford May 2019 approved by Prof. Jeanine Hunter Faculty Advisor © 2019 Aaron Ford ALL RIGHTS RESERVED ABSTRACT Helicopter Dynamics Concerning Retreating Blade Stall on a Coaxial Helicopter by Aaron Ford A model of helicopter blade flapping dynamics is created to determine the occurrence of retreating blade stall on a coaxial helicopter with pusher-propeller in straight and level flight. Equations of motion are developed, and blade element theory is utilized to evaluate the appropriate aerodynamics. Modelling of the blade flapping behavior is verified against benchmark data and then used to determine the angle of attack distribution about the rotor disk for standard helicopter configurations utilizing both hinged and hingeless rotor blades. Modelling of the coaxial configuration with the pusher-prop in straight and level flight is then considered. An approach was taken that minimizes the angle of attack and generation of lift on the advancing side while minimizing them on the retreating side of the rotor disk. The resulting asymmetric lift distribution is compensated for by using both counter-rotating rotor disks to maximize lift on their respective advancing sides and reduce drag on their respective retreating sides. The result is an elimination of retreating blade stall in the coaxial and pusher-propeller configuration. Finally, an assessment of the lift capability of the configuration at both sea level and at “high and hot” conditions were made.
    [Show full text]
  • REPORT No. 201
    REPORT No. 201 THE EFFECTS OF -SHIELDING THE THIS OF AIRFOILS By ELLIOTT G. IWD Langley Memorial Aeronautical Laboratory 3-M REPORT No. 201 THE EFFECTS OF SHIELDING THE TIPS OF AIRFOILS By ELLIOTT G. REID SUMMARY Tests have recently been made at Langley Memorial Aeronautical Laboratory to ascertain whet her the aerodynamic characteristics of an airfoil might be subst antiall-j -impro~ed by imposing certain limitations upon the airflow about its tips. AU of the moditied forms were slightly inferior to the plain airfoil at small lift coefikients; however, by mounting thin plates, in planes perpendicular to the span, at the W@ tips, the characteristics were impro~ed throughout the range above three-tenths of the masimum lift coefficient. With this form of limitation the detrimental effect was slight; at the higher lift .—— coefEcients there resulted a eorsiderable reduction of induced drag and, consequently, of pow-er required for sustentation. The s16pe of the curve of lift ~erws angle of attack was increased. OUTLINE OF TESTS These tests wwe directed to-ward the disco~ery of some economical means of increasing the “ effecti~e aspect ratio” of an airfol As it. is recognized that the induced drag of an airfoiI is inversely proportional to its aspect ratio and that elimination of the transverse velocity, components of the air.tlow about a wing reproduces, in effecfi, the conditions which wouId exist with Mnite aspect ratio, it was planned to investigate the effects of elimination of a portion of the transverse flow by. fln.ite barriers at. the tips and ‘also by the production of an aer~- dcynamic counterforee, in lieu of the com- straints:-by the localization of severe washout at the tzps.
    [Show full text]
  • May 1983 Issue of Soaring Magazine
    Cambridge Introduces The New M KIV NA V Used by winners at the: 15M French Nationals U.S. 15M Nationals U.S. Open Nationals British Open Nationals Cambridge is pleased to announce the Check These Features: MKIV NAV, the latest addition to the successful M KIV System. Digital Final Glide Computer with • "During Glide" update capability The MKIV NAV, by utilizing the latest Micro­ • Wind Computation capability computer and LCD technology, combines in • Distance-to-go Readout a single package a Speed Director, a • Altitude required Readout 4-Function Audio, a digital Averager, and an • Thermalling during final glide capability advanced, digital Final Glide Computer. Speed Director with The MKIV NAV is designed to operate with the MKIV Variometer. It will also function • Own LCD "bar-graph" display with a Standard Cambridge Variometer. • No effect on Variometer • No CRUISE/CLIMB switching The MKIV NAV is the single largest invest­ ment made by Cambridge in state-of-the-art Digital 20 second Averager with own Readout technology and represents our commitment Relative Variometer option to keeping the U.S. in the forefront of soar­ ing instrumentation. 4·Function Audio Altitude Compensation Cambridge Aero Instruments, Inc. Microcomputer and Custom LCD technology 300 Sweetwater Ave. Bedford, MA 01730 Single, compact package, fits 80mm (31/8") Tel. (617) 275·0889; TWX# 710·326·7588 opening Mastercharge and Visa accepted BUSINESS. MEMBER G !TORGLIDING The JOURNAL of the SOARING SOCIETYof AMERICA Volume 47 • Number 5 • May 1983 6 THE 1983 SSA INTERNATIONAL The Soaring Society of America is a nonprofit SOARING CONVENTION organization of enthusiasts who seek to foster and promote all phases of gliding and soaring on a national and international basis.
    [Show full text]
  • Robins 50E ARF Scale
    SebArt professional line RobinS 50E ARF scale ASSEMBLY MANUAL The real plane The Robin DR400 is a wooden sport monoplane, conceived by Pierre Robin and Jean Délémontez. The Robin with a forward-sliding canopy, the DR400 flew in 1972. It has a tricycle undercarriage, and can carry four people. The DR400 aircraft have the 'cranked wing' configuration, in which the dihedral angle of the outer wing is much greater than the inboard. This model is considered easy to fly by many and quiet during flight due to its wooden frame. The wing is a distinctive feature of this airplane; the Robin is light, stiff and strong, with the dihedral of the outer panels imparting substantial lateral stability in flight. Being fabric covered, it presents a smooth surface to aid airflow, unhindered by the typical overlapping panels or rivets found on metal aircraft. The secret to the DR400's relatively high performance lies in the pronounced washout in the outer panels. Since they have a lower angle of attack to the airflow than the centre section, they create less drag in cruise flight. Specifications: Year Built: 1968 Capacity: 4 persons Length: 6.96 m (22 ft 10 in) Wingspan: 8.72 m (28 ft 7¼ in) Wing area: 14.20 m2 (152.85 ft2) Empty weight: 600 kg (1323 lb) Powerplant: 1 × Lycoming O-360-four piston engine, 134 kW (180 hp) Performance Maximum speed: 278 km/h (173 mph) Range: 1450 km (900 miles) Service ceiling: 4715 m (15,470 ft) The model The RobinS 50E ARF scale, was designed by the 15 times Italian Champion Sebastiano Silvestri, vice-European Champion and 2 time F.A.I World Cup winner F3A.
    [Show full text]
  • A Method for Localizing Wing Flow Separation at Stall to Alleviate Spin Entry Tendencies
    78-1476 A Method for Localizing Wing Flow Separation \* at Stall to Alleviate Spin Entry Tendencies T. W. Feistel and S. B. Anderson, NASA Ames Research Center, Moffett Field, Ca.; and R. A. Kroeger, University of Michigan, Ann Arbor, Mich. AlAA AIRCRAFT SYSTEMS AND TECHNOLOGY CONFERENCE L Los Angeles, CalifJAugust 21-23,1978 This is a US. Government work and is not copyrightable under U.S.C. 105. -- A \IETIIOD FOR 1I)CALIZING WISC fLW SEPARRTION .\T STALI TO ALI.FVIAT? SPIN ENTRY TENDENCIES T. W. Fe15t~!l' and S. B. AndersonT Am. Research Center, NASA. MJffs>tt Field. Calrforn1.3 md R. &. Krocger' university Of Mlch1g.m. Ann li-bor. Mic:irgan ABSTRACT Theoretical models of three-dimensional wings, using a nonlinear-lifting-line approach with a sim- A wing leading-edge modification has been ulated Stalled wing section, had suggested that developed, applicable at present to single-engine strong vorticity would be Shed at the edges of the light aircraft, which produces stabilizing vortices unattached section. A wind-tunnel model was fabri- at stall and beyond. These Vortices have the effect cated with partial span slats added along the of fixing the stall pattern of the wing such that entire leading-edge except for a ma11 length near the various portions of the wing upper surface stall the mid-semispan. These differences in leading- nearly symmetrically. The lift coefficient produced edge configuration were intended to produce a is essentially constant to very high angles of strong streamwise vorticity around the stalled sec- attack above the Stall angle of the unmodified wing.
    [Show full text]
  • Tailless Aircraft : an Overview
    o Journal of Aeronautics and Aerospace ISSN: 2168-9792 Engineering Editorial Tailless Aircraft : An Overview Srikanth Nuthanapati Department of Aeronautics, IIT Madras,Chennai,India. EDITORIAL Apart from its main wing, it lacks a tail assembly and any other Low or null pitching moment airfoils, as seen in the Horten horizontal surface. The main wing incorporates aerodynamic family of sailplanes and fighters, provide an alternative. These control and stabilisation functions in both pitch and roll. A have a unique wing segment with reflex or reverse camber on the tailless design might nevertheless feature a rudder and a vertical back or entire wing. The flatter side of the wing is on top, while fin (vertical stabiliser). Low parasitic drag, similar to the Horten the steeply curved side is on the bottom, resulting in a high angle H.IV soaring glider, and strong stealth qualities, similar to the of attack in the front part. Northrop B-2 Spirit bomber, are theoretical advantages of the Fitting large elevators to a standard airfoil and trimming them tailless configuration. The tailless delta has proven to be the considerably upwards can approximate reflex camber; the most successful tailless layout, particularly for combat aircraft, centre of gravity must also be moved forward from its normal albeit the Concorde airliner is the most well-known tailless position. Reflex camber tends to cause a tiny downthrust due to delta. the Bernoulli effect, thus the wing's angle of attack is increased A horizontal stabiliser surface separate from the main wing is to compensate. This, in turn, adds to the drag.
    [Show full text]
  • Design Development and CFD Simulation of a Variable Twist Wing
    Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-5, 2017 ISSN: 2454-1362, http://www.onlinejournal.in Design Development and CFD Simulation of a Variable Twist Wing 1 2 3 G.Sawan Kumar , Shuvendra Mohan , R.Surendra Rao 1 Space And Astronautical Engineering, University of Sapienza, Rome, Italy 2Aeronautical Engineering, Institute of Aeronautical Engineering, Dundigal, Hyderabad, India 3Mechanical Engineering Department, Kasi reddy naryan reddy college of engineering and research, Hyderabad, India Abstract: Wing twist is an aerodynamic feature these equations are difficult to solve. For a wing to added to aircraft wings to adjust lift distribution produce "lift", it must be oriented at a suitable angle along the wing. Often, the purpose of lift of attack relative to the flow of air past the wing. redistribution is to ensure that load distribution is When this occurs the wing deflects the airflow uniform from wing tip to root, it ensures that the downwards, "turning" the air as it passes the wing. effective angle of attack is always lower at the wing Since the wing exerts a force on the air to change its tip than at the root, meaning the root will stall before direction, the air must exert a force on the wing, the tip. This is desirable because the aircraft's flight equal in size but opposite in direction. This force control surfaces are often located at the wingtip, and manifests itself as differing air pressures at different the variable stall characteristics of a twisted wing points on the surface of the wing. alert the pilot to the advancing stall while still A region of lower-than-normal air pressure is allowing the control surfaces to remain effective, generated over the top surface of the wing, with a meaning the pilot can usually prevent the aircraft higher pressure existing on the bottom of the wing.
    [Show full text]
  • The Aerodynamics of the Spitfire.Pdf
    Journal of Aeronautical History Draft 2 Paper No. 2016/03 The Aerodynamics of the Spitfire J. A. D. Ackroyd Abstract This paper is a sequel to earlier publications in this Journal which suggested a possible origin for the Spitfire’s wing planform. Here, new material provided by Collar’s drag comparison between the Spitfire and the Hurricane is described and rather more details are given on the Spitfire’s high subsonic Mach number performance. The paper also attempts to bring together other existing material so as to provide a more extensive picture of the Spitfire’s aerodynamics. 1. Introduction To celebrate the Spitfire’s eightieth year, the Royal Aeronautical Society’s Historical Group organised the Spitfire Seminar held at Hamilton Place, London, on 19th September 2016. This celebration offered the author the opportunity to talk about the aerodynamics of the (1, 2) Spitfire. Part of that lecture was based on material already published in this Journal which suggested that the semi-elliptical wing planform adopted could have come from earlier publications by Prandtl. Section 2 offers further thoughts on this planform choice, in particular how this interlinked with the structural decision to place the single wing spar at the quarter-chord point and the selection of the aerofoil section. Since the publication of References 1 and 2, new material has come to light in the form of an investigation by A. R. Collar in 1940 which compares the drags experienced by the Spitfire and the Hurricane. This investigation, described in Section 3, indicates that a significant part of the Spitfire’s lower drag can be attributed to the better boundary-layer behaviour produced by its wing’s thinner aerofoil section.
    [Show full text]
  • THE DEFINITIVE GUIDE to PROPERLY RIGGING the WEEDHOPPER WING By: Dean A
    THE DEFINITIVE GUIDE TO PROPERLY RIGGING THE WEEDHOPPER WING By: Dean A. Scott, July 1,2003 Some Background A typical wing or propeller produces lift when it’s at an angle of attack (AOA) between 2 and 15 degrees. At 15 degrees AOA they will stall. So, In order to prevent either one of the plane’s wings from dropping due to such a stall condition and causing the plane to dive and roll into a spin, washout is used to stabilize the wing by slanting the tips of the wing upwards at the trailing edge (TE). This slight twist of the wing progressively reduces the AOA out towards the wing tips so that the tips still produce lift even if the root is stalled. With the wing tips still flying and the root stalled, the wings maintain a level attitude and a stall spin is prevent. A propeller is a good example of washout. Compared to a wing, they have an exaggerated twist with the tips at only a few degrees AOA (pitch) while the root has a far greater AOA. This is because the prop has a greatly reduced radial velocity towards the center, thus requiring an increasing AOA or pitch to produce lift/thrust. Since the Weedhopper flies at an AOA of 2.4 degrees in level cruise, wing tip washout must be set to at or near level to reduce drag. These instructions explain how to do that. But first, the wing’s dihedral, or degree of upward slant as a whole, needs to be set first.
    [Show full text]
  • An Electric-Powered RC Version of the French Light Home-Built
    by Laddie Mikulasko An electric-powered RC version of the French light home-built FOR MANY YEARS, I set my sights on building a scale model of the famous French home-built Jodel D.9 Bébé. It has a long history. Eduardo Joly and Jean Delemontez began building the prototype in 1946. The name “Jodel” was derived from a combination of their names. The pair started constructing the airplane without plans; they drew the individual parts’ shapes directly onto the wood. The D.9 was first flown in 1948 with an old 19-horsepower Poinsard engine and showed excellent flying qualities. It soon became the most popular home-built in Europe, and then its popularity spread around the world. More than 5,000 D.9s have been built from plans or kits, and many are constructed to this day. The D.9 was a starting point in the series of the manufacturers’ designs. The Jodel Company was eventually formed, and all of the additional designs were produced. A Volkswagen engine powered most of the early airplanes. A beautifully painted D.9 that Bernard Schacknowski of Paris, Illinois, built in 1963 motivated me to build the model. His was one of the first, if not the first, of those aircraft constructed in 1 the US. He streamlined the airplane’s nose by As is the full-scale version, this /4-scale enclosing the Continental A-40 engine. Jodel D-9 Bebe is a sweetheart on landing. October 2009 25 Photos by the author Above: All ribs are cut out, and the main and auxiliary spars are in the process of construction.
    [Show full text]
  • (12) Patent Application Publication (10) Pub. No.: US 2014/0021302 A1 Gionta Et Al
    US 201400213 O2A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2014/0021302 A1 Gionta et al. (43) Pub. Date: Jan. 23, 2014 (54) SPN RESISTANT AIRCRAFT Publication Classification CONFIGURATION (51) Int. Cl. (71) Applicant: ICON Aircraft, Inc., Los Angeles, CA B64C2L/00 (2006.01) (US) B64C2L/It (2006.01) (52) U.S. Cl. (72) Inventors: Matthew Gionta, Tehachapi, CA (US); CPC ................. B64C 21/00 (2013.01); B64C 21/10 Jon Karkow, Tehachapi, CA (US); John (2013.01) Roncz, Elkhart, IN (US); Dieter USPC ......................... 244/200.1; 244/198: 244/200 Koehler, Powell Butte, OR (US); Len Fox, Bend, OR (US); David Lednicer, (57) ABSTRACT Redmond, WA (US) A configuration and system for rendering an aircraft spin resistant is disclosed. Resistance of the aircraft to spinning is accomplished by constraining a stall cell to a wing region (21) Appl. No.: 13/946,572 adjacent to the fuselage and distant from the wing tip. Wing features that facilitate this constraint include but are not lim (22) Filed: Jul.19, 2013 ited to one or more cuffs, stall strips, Vortex generators, wing twists, wing Sweeps and horizontal stabilizers. Alone or in combination, aircraft configuration features embodied by the Related U.S. Application Data present invention render the aircraft spin resistant by con (60) Provisional application No. 61/674.267, filed on Jul. straining the stall cell, which allows control surfaces of the 20, 2012. aircraft to remain operational to control the aircraft. 230 Patent Application Publication Jan. 23, 2014 Sheet 1 of 6 US 2014/002 1302 A1 Patent Application Publication Jan.
    [Show full text]
  • How Much and Where By: David Andersen
    Why? How Much and Where by: David Andersen Washout is a twist in a wing that causes the wingtip to meet the airflow at a lower angle than the root in normal upright flight. Some planes don’t need it; some planes can’t fly without it. It’s not just to prevent tip stalls! Why ... Washout causes the root of the wing to stall before the wingtips stall. The subsequent loss of lift in the root area gently lowers to the nose or prevents it from rising further, preventing the entire wing from stalling suddenly and provoking an unwanted snap roll. Stalls do not always occur at low airspeeds. Pylon racers, for example, can stall in high-G turns, sometimes with disastrous results. At high angles of attack, ailerons become less effective because they are both lifting, and the difference in lift becomes less with increasing angle of attack. Washout causes the ailerons to meet the air at a lower angle. This improves aileron effectiveness at all attitudes, especially at low airspeeds. In a banked turn, the down aileron increases lift and drag while the up aileron reduces lift and drag. The difference in wingtip drag tends to yaw the airplane in a direction opposite to the turn - “adverse yaw.” Washout tends to reduce the effects of adverse yaw but only in the portions of the ailerons that are close to zero angle of attack. Some airplanes are trimmed so that there is less down aileron travel than up travel, called “aileron differential.” But aileron differential is only a partial cure.
    [Show full text]