XV-15 litho - NASA's History Office

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Figure 20. Tiedown tests of the XV-3 with protective shields at Bell in July, 1957. (Bell Photograph 220955) Figure 21. XV-3 in hover at Ames Research Center. (Bell Photograph 228649) 14 In the following 18 months, the XV-3 (tail number 4148) with its new rotor system underwent two wind tunnel entries in the 40- by 80-foot wind tunnel (September-October 1957 and October 1958) and an additional series of ground tiedown and flight tests. During this period further changes were made to improve stability, including the reduction of the rotor diameter to 23 feet, the addition of external struts to stiffen the wing, and a significant increase in the stiffness of the rotor controls. The configuration that emerged accomplished the elusive goal of completing a dynamically stable full conversion to the airplane mode. This occurred at Bell on December 18, 1958, with test pilot Bill Quinlan at the controls. Subsequent flights explored the effect of wing stiffness (by modifying the strut attachments) and expanded the flight envelope within the fairly narrow range of the XV-3’s performance capabilities. Government Flight Tests The XV-3 was transported to Edwards Air Force Base where, from May through July 1959, Air Force Major Robert Ferry conducted a Government flight evaluation. The tests included handling qualities assessments, Short Takeoff and Landing (STOL) operations, and autorotation demonstrations. The Air Force test report, 7 authored by Project Engineer Lt. Wallace H. (Wally) Deckert, USAF, and Major Ferry, noted numerous deficiencies in the performance and flying qualities of the aircraft. However, in spite of the deficiencies, the report concluded that “the fixed-wing prop-rotor (i.e. the tilt rotor) principle is feasible and should be given serious consideration in future Vertical or Short Takeoff and Landing (V/STOL) aircraft design competition.” “The XV-3 demonstrated that the fixed-wing prop-rotor con- 7 W. H. Deckert, R. G. Ferry, “Limited Flight Evaluation of the XV-3 Aircraft,” TR-60-4 ARDC XV-3, May 1960.
cept is operationally practical with safety and complexity comparable to helicopters.” After the conclusion of the flight program at Edwards AFB, the XV-3 was transported to NASA ARC onboard an Air Force C-130, where flight testing continued until July 1962 (figure 21). The first full tilt rotor conversion at Ames was performed by test pilot Fred Drinkwater on August 12, 1959 (figure 22). This flight program was followed by an additional entry in the Ames 40by 80-foot wind tunnel (in June-July 1962, figure 23) to investigate the effects of changes to the pitch-flap coupling on rotor flapping and highspeed airplane mode stability. Pitch-flap coupling refers to a feature provided by the hub design wherein the blade pitch angle is changed in a manner that alters the amount of outof-plane flapping motion that occurs. A standard stabilizing pitch-flap coupling, referred to as δ 3 ,reduces the flapping displacement by reducing the pitch angle as flapping increases. After another modification (this time to increase the pylon/wing stiffness) the XV-3 was able to reach a speed of 155 knots before indications of low damping, i.e. aeroelastic instability, were seen. While this was a definite improvement over the earlier stability limits of the XV-3, it would still be inadequate for the intended military mission application of the tilt rotor aircraft and was substantially below the predicted performance capability of this aircraft type. Stability Validation In 1965, after a period of model-scale testing and analytical studies, Bell funded a ground test to continue its investigation of XV-3 tilt rotor dynamics. To further pursue this work in a full-scale wind tunnel test, Robert (Bob) Lynn, Bell’s Chief of Research and Development (who later was Bell’s Senior Vice President, Top: Figure 22. XV-3 in airplane mode of flight near Ames Research Center. (Bell Photograph 028304) Bottom: Figure 23. XV-3 in the Ames Research Center 40- by 80- ft. wind tunnel. (AMES Photograph A37017) 15
Page 1: The History of The XV-15 Tilt Rotor
Page 5: Contents Prologue . . . . . . . . .
Page 9: Dedication The story of the success
Page 13: Foreword The development of tilt ro
Page 17 and 18: List of Figures Figure 1 Leonardo d
Page 19 and 20: Figure 41 Simultaneous static test
Page 21 and 22: Figure A-2 Transcendental Model 2 t
Page 23 and 24: List of Acronyms AARL Army Aeronaut
Page 25: TRENDS Tilt Rotor Engineering Datab
Page 28 and 29: Figure 2. Illustration of vertical
Page 30 and 31: Figure 4. McDonnell XV-1 compound h
Page 32 and 33: Figure 7. Henry Berliner tiltpropel
Page 34 and 35: Top: Figure 9. The Baynes Heliplane
Page 36 and 37: Figure 13. Illustration from the Ha
Page 38 and 39: Figure 17. Bob Lichten, extreme lef
Page 42 and 43: 16 Research and Engineering), obtai
Page 44 and 45: 18 management continued to show int
Page 46 and 47: 20 Building the Technology Base Aer
Page 48 and 49: Figure 25. Bell 25-ft. diameter pro
Page 50 and 51: Figure 28. Performance tests of 5-f
Page 52 and 53: Figure 31. Bell 25-ft. diameter pro
Page 54 and 55: 28 Tilt Rotor Research Aircraft Pro
Page 56 and 57: 30 During the late 1960s and early
Page 58 and 59: 32 range of loading conditions and
Page 60 and 61: 34 The initial projected cost of $4
Page 62 and 63: Figure 35. Illustration of the Boei
Page 64 and 65: Figure 36. 1/5 scale XV-15 model in
Page 66 and 67: 40 under the contract. To accomplis
Page 68 and 69: 42 Aircraft Development The primary
Page 70 and 71: 44 Test stand angle box Test stand
Page 72 and 73: Figure 40. Proprotor response to co
Page 74 and 75: Figure 41. Simultaneous static test
Page 76 and 77: 50 helicopters. For the conversion
Page 78 and 79: 52 Prior to the start of flight ope
Page 80 and 81: Figure 44. Initial Bell tiedown sho
Page 82 and 83: 56 degrees 25 and a brief assessmen
Page 84 and 85: Figure 45. XV-15 in the Ames Resear
Page 86 and 87: 60 NAVAIR managers as a means of de
Page 88 and 89: Figure 46. Government and Bell pers
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Figure 49. Tiedown test facility at
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66 Wheel height Top: Figure 51. Met
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68 Symmetric beam mode Antisymmetri
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Figure 55. XV-15 during short takeo
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Top: Figure 56. Flow visualization
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74 during “degraded” flight con
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Figure 59. Hover acoustics tests du
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78 Nose weight Top: Figure 61. Typi
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80 Following the completion of cont
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82 After the proprotors stopped, th
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84 sudden stoppage of the right eng
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86 A reconversion to the helicopter
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88 Paris Air Show By early 1981, th
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90 enroute from Farnborough to Fran
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Top: Figure 66. Senator Goldwater i
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Figure 69. Shipboard evaluations of
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Figure 71. XV-15 at the New York Po
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98 Crash (October 16 and 17, 1991).
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100 The End of an Era By the mid 19
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Top: Figure 73. XV-15 at the Dallas
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104 management system was very effe
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106 could make use of the same flig
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Figure 76. The Bell tilt rotor eagl
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110 demonstrations two years earlie
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112 Future Tilt Rotor Aircraft By t
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114 tiltrotor aircraft program. Thi
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116 Model 1-G Characteristics Power
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Figure A-3. Transcendental Model 2
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Figure A-4. XV-3 three-view drawing
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Figure A-5. XV-3 inboard drawing, s
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Nacelle angle (degrees) 124 120 90
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Figure A-8. General layout and majo
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Figure A-9. Side view inboard profi
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Figure A-11. XV-15 height-velocity
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132 Weight Design . . . . . . . . .
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134 WBS LEVEL: Bell Army/NASA I II
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136 US Army Air Mobility Research a
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138 Army/NASA (continued) Staff (19
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140 Appendix C—Chronology 1452-15
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142 1968 Boeing Vertol awarded cont
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144 November, Initial piloted simul
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146 24 March 1982 XV-15 demonstrate
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148 30 July 1987 FAA/NASA/DOD Tilt
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150 21 August 1990 V-22 reached 340
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152 14 June 1993 The Department of
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154 Appendix D—Awards and Records
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Figure D-1. Jean Tinsley, first wom
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Figure E-3. XV-15 flying by the Sta
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Figure E-7. Bell test pilots Roy Ho
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Figure E-11. Ken Wernicke, Bell til
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164 Appendix F—Bibliography Tilt
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166 Ball, J. C. “XV-15 Shipboard
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168 Churchill, G. B.; Dugan, D. C.
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170 Edenborough, H. K. “Investiga
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172 Harendra, P. B.; Joglekar, M. J
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174 Kvaternik, Raymond G. “Studie
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176 Magee, J. P.; Pruyn, R. “Pred
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178 Martin, Stanley, Jr.; Erb, Lee
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180 Rutledge, Charles K.; George, A
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182 Tischler, M. B.; Leung, J. G. M
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184 Whitaker, H. L.; Cheng, Yi. “
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186 Daniel C. Dugan Daniel Dugan gr
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188 Carnet, 88 Carpenter, Ron, 91 C
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190 Moffett Airfield, Moffett Field
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Monographs in Aerospace History Lau
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National Aeronautics and Space Admi
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