XV-15 litho - NASA's History Office

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100 The End of an Era By the mid 1990s, the flight research situation in the Government was changing. NASA Administrator Daniel Goldin, in an attempt to reduce the operating costs of the Agency, directed that all flight activities were to be consolidated at one research center, the Dryden Flight Research Center (DFRC). For nearly two years following that directive, heated debates raged between NASA Headquarters (for consolidation) and the Centers, local officials, and members of Congress (from affected congressional districts) who argued for the continuation of flight activities at the Centers. Ultimately the decision was made to move all NASA flight test activity to DFRC by January 1, 1998. Meanwhile, XV-15 N703NA was undergoing a major inspection at Ames. In addition to the scheduled transmission overhaul, the composite blade cuffs were modified to prevent a reoccurrence of the failure that resulted in the emergency landing in September 1991, and modifications to the proprotor control system were designed to correct the dynamic problems and load limitations encountered during the initial flights with the advanced technology blade (ATB). When the final decision was made by NASA Headquarters to terminate XV-15 operations at Ames in early 1994, the inspection and modification work ceased and the XV- 15 TRRA was placed in temporary storage at Ames. Starting Over The availability of XV-15 N703NA was seen as an unexpected opportunity by Bell. Having lost N702NA in the unfortunate accident in August 1992, and with an ongoing requirement to conduct tilt rotor research, demonstrations, and applications evaluations in support of the V-22 program, Larry Jenkins, Bell’s director of technology, requested that a new bailment be established for N703NA. The NASA/Army owners of the XV-15, with no funding and no prospects for continuing the XV-15 flight test program, consented to a new agreement. The terms of the new bailment, described in a Memorandum of Agreement effective April 21, 1994, were approved by the NASA Ames Director, Dr. Ken Munechika; the NASA Associate Administrator for Aeronautics, Dr. Wesley Harris; the Director of the Army Aeroflightdynamics Directorate, Andrew W. Kerr; the Executive Director of the Army Aviation Research, Development, and Engineering Center, Thomas L. House; and Bell President Webb Joiner. The aircraft was again disassembled and was shipped from Ames to Bell’s flight test center onboard flatbed trucks immediately after the bailment was authorized. The delivery of that aircraft with the Boeing Helicopters composite blades (ATB) presented a problem for Bell. The unplanned cost of refurbishing the aircraft during the current fiscal year represented a large portion of Bell’s tilt rotor discretionary research funds. With inadequate funding for the development of the control system improvements, and with low confidence in compatibility of the ATB with the XV-15 and in the integrity of some of the ATB’s composite components, Bell sought an alternate approach. Bell’s preferred solution was to return to the use of their metal blades fabricated for the XV-15.
A review of the availability of flightworthy metal blades brought the plan to an immediate halt. It turned out that when the NASA/Army TRRA team at Ames initiated the ATB evaluations on the XV-15, the metal blades from N703NA were sent to Bell to replace the higher flight-time blades on N702NA, some of which had become unserviceable due to skin cracks. When N702NA crashed, all of its proprotor blades (from N703NA) were destroyed leaving only two usable left metal blades and four usable right blades. Short of fabricating a new blade for the left proprotor at great expense, there was no hope of obtaining the required blade. At this point another of those remarkable events that have periodically rescued the program from a seemingly unsolvable situation occurred. The Ames longterm hardware storage facility, located at Camp Parks near Oakland, California, requested the aircraft projects to remove or dispose of the aircraft-related items in storage since, under the new flight activities consolidation plan, the Ames aircraft assets were now to be moved away, primarily to DFRC. While searching through the large warehouse, a crate containing a left XV-15 metal blade was discovered. The blade, still in primer paint was apparently unused. The documents indicated that this blade was fabricated for structural fatigue testing under the TRRA contract, but funding limitations at that time caused that test to be eliminated. After inspection at Bell by Ernie Schellhase, who had designed these blades in the late 1960s under Bell’s IR&D funding, the blade was declared flightworthy. It was refinished and installed on N703NA, completing the required proprotor “shipset.” Once again, lady luck smiled on the TRRA. With the proprotor blade problem question resolved, Bell stepped up the refurbishment of N703NA. At the completion of this refurbishment, the aircraft had the original metal blades, a new data acquisition system (similar to the system being used on the V-22), and had the Ames-modified automatic flight control system restored to Bell’s control laws. Because of the extended time period since the last operation of the XV-15, arrangements were made for the Bell pilots to perform training sessions in the Ames simulator as the aircraft was nearing flight readiness. On March 3, 1995, test pilots Ron Erhart and Roy Hopkins returned this aircraft to flight at the Bell Flight Test Center, Arlington Texas, nearly 16 years after its initial flight at the same location. Deja Vu After a brief checkout period, XV-15 N703NA was pressed into action as the tilt rotor technology demonstrator, this time in executive transport colors including painted-on simulated windows. On April 21, 1995, it became the first tilt rotor to land at the world’s first operational vertiport, the Dallas Convention Center Heliport/Vertiport (figure 73). In June, when the Bell-Boeing V-22 Osprey made its first international public debut at the forty-first Paris Air Show, the XV-15 was also present (figure 74), marking a triumphant return 14 years after its initial appearance. With both aircraft performing flight demonstrations on the 101
Page 1:
The History of The XV-15 Tilt Rotor
Page 5:
Contents Prologue . . . . . . . . .
Page 9:
Dedication The story of the success
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Foreword The development of tilt ro
Page 17 and 18:
List of Figures Figure 1 Leonardo d
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Figure 41 Simultaneous static test
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Figure A-2 Transcendental Model 2 t
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List of Acronyms AARL Army Aeronaut
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TRENDS Tilt Rotor Engineering Datab
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Figure 2. Illustration of vertical
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Figure 4. McDonnell XV-1 compound h
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Figure 7. Henry Berliner tiltpropel
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Top: Figure 9. The Baynes Heliplane
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Figure 13. Illustration from the Ha
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Figure 17. Bob Lichten, extreme lef
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Figure 20. Tiedown tests of the XV-
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16 Research and Engineering), obtai
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18 management continued to show int
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20 Building the Technology Base Aer
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Figure 25. Bell 25-ft. diameter pro
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Figure 28. Performance tests of 5-f
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Figure 31. Bell 25-ft. diameter pro
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28 Tilt Rotor Research Aircraft Pro
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30 During the late 1960s and early
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32 range of loading conditions and
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34 The initial projected cost of $4
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Figure 35. Illustration of the Boei
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Figure 36. 1/5 scale XV-15 model in
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40 under the contract. To accomplis
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42 Aircraft Development The primary
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44 Test stand angle box Test stand
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Figure 40. Proprotor response to co
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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
Page 90 and 91: Figure 49. Tiedown test facility at
Page 92 and 93: 66 Wheel height Top: Figure 51. Met
Page 94 and 95: 68 Symmetric beam mode Antisymmetri
Page 96 and 97: Figure 55. XV-15 during short takeo
Page 98 and 99: Top: Figure 56. Flow visualization
Page 100 and 101: 74 during “degraded” flight con
Page 102 and 103: Figure 59. Hover acoustics tests du
Page 104 and 105: 78 Nose weight Top: Figure 61. Typi
Page 106 and 107: 80 Following the completion of cont
Page 108 and 109: 82 After the proprotors stopped, th
Page 110 and 111: 84 sudden stoppage of the right eng
Page 112 and 113: 86 A reconversion to the helicopter
Page 114 and 115: 88 Paris Air Show By early 1981, th
Page 116 and 117: 90 enroute from Farnborough to Fran
Page 118 and 119: Top: Figure 66. Senator Goldwater i
Page 120 and 121: Figure 69. Shipboard evaluations of
Page 122 and 123: Figure 71. XV-15 at the New York Po
Page 124 and 125: 98 Crash (October 16 and 17, 1991).
Page 128 and 129: Top: Figure 73. XV-15 at the Dallas
Page 130 and 131: 104 management system was very effe
Page 132 and 133: 106 could make use of the same flig
Page 134 and 135: Figure 76. The Bell tilt rotor eagl
Page 136 and 137: 110 demonstrations two years earlie
Page 138 and 139: 112 Future Tilt Rotor Aircraft By t
Page 140 and 141: 114 tiltrotor aircraft program. Thi
Page 142 and 143: 116 Model 1-G Characteristics Power
Page 144 and 145: Figure A-3. Transcendental Model 2
Page 146 and 147: Figure A-4. XV-3 three-view drawing
Page 148 and 149: Figure A-5. XV-3 inboard drawing, s
Page 150 and 151: Nacelle angle (degrees) 124 120 90
Page 152 and 153: Figure A-8. General layout and majo
Page 154 and 155: Figure A-9. Side view inboard profi
Page 156 and 157: Figure A-11. XV-15 height-velocity
Page 158 and 159: 132 Weight Design . . . . . . . . .
Page 160 and 161: 134 WBS LEVEL: Bell Army/NASA I II
Page 162 and 163: 136 US Army Air Mobility Research a
Page 164 and 165: 138 Army/NASA (continued) Staff (19
Page 166 and 167: 140 Appendix C—Chronology 1452-15
Page 168 and 169: 142 1968 Boeing Vertol awarded cont
Page 170 and 171: 144 November, Initial piloted simul
Page 172 and 173: 146 24 March 1982 XV-15 demonstrate
Page 174 and 175: 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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