m Reverted unexplained changes
|
|
||
(36 intermediate revisions by 22 users not shown) | |||
Line 1: | Line 1: | ||
{{Short description|American experimental tiltrotor aircraft}} |
|||
{{short description|Experimental tiltrotor, used to demonstrate the concept's high speed performance relative to conventional helicopters}} |
|||
{{Multiple issues| |
|||
{{More citations needed|date=April 2010}} |
{{More citations needed|date=April 2010}} |
||
{{Lead too short|date=December 2023}} |
|||
}} |
|||
<!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout, and guidelines. --> |
<!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout, and guidelines. --> |
||
{|{{Infobox aircraft begin |
{|{{Infobox aircraft begin |
||
Line 14: | Line 17: | ||
|introduced= |
|introduced= |
||
|retired= 2003 |
|retired= 2003 |
||
|status= |
|status= Prototype |
||
|primary user= [[NASA]] |
|primary user= [[NASA]] |
||
|more users= |
|more users= |
||
Line 22: | Line 25: | ||
|developed from= |
|developed from= |
||
|variants with their own articles= |
|variants with their own articles= |
||
|developed into= [[V-22 Osprey]] |
|developed into= [[V-22 Osprey]]<br>[[AgustaWestland AW609]] |
||
}} |
}} |
||
|} |
|} |
||
Line 30: | Line 33: | ||
==Development== |
==Development== |
||
===Early VTOL rotor aircraft=== |
===Early VTOL rotor aircraft=== |
||
The idea of building [[VTOL |
The idea of building [[VTOL]] aircraft using helicopter-like rotors at the wingtips originated in the 1930s. The first design resembling modern tiltrotors was patented by George Lehberger in May 1930, but he did not develop the concept further. In [[World War II]], a [[Germany|German]] [[prototype]] called the [[Focke-Achgelis Fa 269]] was developed starting in 1942, but it never flew. |
||
Two prototypes that made it to flight were the one-seat [[Transcendental Model 1-G]] and two-seat Transcendental Model 2, both powered by single reciprocating engines. Development started on the Model 1-G in 1947, and it flew in 1954. The Model 1-G flew until a crash in [[Chesapeake Bay]] on 20 July 1955, destroying the prototype aircraft but not seriously injuring the pilot. The Transcendental 1-G was the first tiltrotor aircraft to have flown, and it accomplished most of a helicopter-to-aircraft transition in flight to within ten degrees of true horizontal aircraft flight. The Model 2 was developed and flew shortly afterward, but it did not fly much beyond hover tests. The [[United States Air Force]] withdrew funding in favor of the Bell XV-3. |
Two prototypes that made it to flight were the one-seat [[Transcendental Model 1-G]] and two-seat Transcendental Model 2, both powered by single reciprocating engines. Development started on the Model 1-G in 1947, and it flew in 1954. The Model 1-G flew until a crash in [[Chesapeake Bay]] on 20 July 1955, destroying the prototype aircraft but not seriously injuring the pilot. The Transcendental 1-G was the first tiltrotor aircraft to have flown, and it accomplished most of a helicopter-to-aircraft transition in flight to within ten degrees of true horizontal aircraft flight. The Model 2 was developed and flew shortly afterward, but it did not fly much beyond hover tests. The [[United States Air Force]] withdrew funding in favor of the Bell XV-3. |
||
Line 36: | Line 39: | ||
The [[Bell XV-3]] was first flown in 1955. Like its predecessors, the XV-3 had the engines in the [[fuselage]] and driveshafts transferring power out to tilting wingtip rotor assemblies. |
The [[Bell XV-3]] was first flown in 1955. Like its predecessors, the XV-3 had the engines in the [[fuselage]] and driveshafts transferring power out to tilting wingtip rotor assemblies. |
||
Other rotor concepts, such as slowed |
Other rotor concepts, such as [[slowed rotor]]s, stopped rotors, folding rotors, and variable-diameter rotors, were investigated for subsequent designs, but Bell engineers [[Kenneth Wernicke]] and Bob Lichten deemed them unfeasible compared to experience with the XV-3 project.<ref name=as-xv3>Miller, Jay. [http://www.airspacemag.com/history-of-flight/origin-species.html "Origin of the Species"]. ''[[Air & Space/Smithsonian]]'', July 2004. Accessed: 17 March 2012.</ref> |
||
===Technological advances=== |
===Technological advances=== |
||
Line 43: | Line 46: | ||
One of the major problems with the early [[tiltrotor]] aircraft designs was that the driveshafts carrying power from the fuselage out to the wingtip rotors, along with the gearbox and tilting mechanisms at the wingtips, had substantial loads placed upon them and were heavy. They were transferring large amounts of power and torque long distances for an aircraft power transmission system. |
One of the major problems with the early [[tiltrotor]] aircraft designs was that the driveshafts carrying power from the fuselage out to the wingtip rotors, along with the gearbox and tilting mechanisms at the wingtips, had substantial loads placed upon them and were heavy. They were transferring large amounts of power and torque long distances for an aircraft power transmission system. |
||
The XV-15 experimental aircraft introduced a major design concept advance: instead of engines in the fuselage, the XV-15 moved the engines out to the rotating wingtip pods, directly coupled to the rotors. The normal path for power was directly from the engine into a speed-reduction gearbox and into the rotor/propeller without any long shafts involved. There was still a driveshaft along the wings for emergency use to transfer power to the opposite rotor in case of engine failure, but that shaft did not normally carry any power loads, |
The XV-15 experimental aircraft introduced a major design concept advance: instead of engines in the fuselage, the XV-15 moved the engines out to the rotating wingtip pods, directly coupled to the rotors. The normal path for power was directly from the engine into a speed-reduction gearbox and into the rotor/propeller without any long shafts involved. There was still a driveshaft along the wings for emergency use to transfer power to the opposite rotor in case of engine failure, but that shaft did not normally carry any power loads, allowingit to be lighter. |
||
The tilting engine concept introduced complexities in the design of the engines and engine pods to be able to shift from operating horizontally to operating vertically. Those problems were addressed fairly early in the XV-15 program. |
The tilting engine concept introduced complexities in the design of the engines and engine pods to be able to shift from operating horizontally to operating vertically. Those problems were addressed fairly early in the XV-15 program. |
||
Line 56: | Line 59: | ||
====Competing designs==== |
====Competing designs==== |
||
[[File:XV-15 N703NA USCG.jpg|thumb|A XV-15 in [[United States Coast Guard|USCG]] |
[[File:XV-15 N703NA USCG.jpg|thumb|A XV-15 in [[United States Coast Guard|USCG]] livery landing on the lawn of the Pentagon, September 1999]] |
||
[[File:Xv-15 inflight.jpg|thumb|right|XV-15 in forward flight]] |
|||
Boeing Vertol proposed its Model 222 (not to be confused with the later [[Bell 222]] conventional helicopter), in which the engines were in fixed pods at the end of each wing, and a small, rotating pod with the rotor was slightly closer to the fuselage on the wing. This design simplified the engine design by keeping it horizontal at all times without having very long driveshafts to the tilting rotors. |
Boeing Vertol proposed its Model 222 (not to be confused with the later [[Bell 222]] conventional helicopter), in which the engines were in fixed pods at the end of each wing, and a small, rotating pod with the rotor was slightly closer to the fuselage on the wing. This design simplified the engine design by keeping it horizontal at all times without having very long driveshafts to the tilting rotors. |
||
In the Bell design, Bell Model 301, the whole wingtip pod rotated between horizontal and vertical, with the engine and rotor assembly fixed together within the pod. This simplified the power transmission, but it had more complicated requirements for the engine design and was probably slightly heavier than the Boeing proposal. |
In the Bell design, Bell Model 301, the whole wingtip pod rotated between horizontal and vertical, with the engine and rotor assembly fixed together within the pod. This simplified the power transmission, but it had more complicated requirements for the engine design and was probably slightly heavier than the Boeing proposal. |
||
After a review of both proposals, NASA selected the Bell 301 for further development, and a contract for further R&D was issued on 31 July 1973. Extensive engineering and testing took the next four years to complete the development of the aircraft. The first of two Bell XV-15s, tail number '''N702NA''', first flew on 3 May 1977. After minimal flight tests at the Bell test facility, the aircraft was moved to Ames Research Center in |
After a review of both proposals, NASA selected the Bell 301 for further development, and a contract for further R&D was issued on 31 July 1973. Extensive engineering and testing took the next four years to complete the development of the aircraft. The first of two Bell XV-15s, tail number '''N702NA''', first flew on 3 May 1977. After minimal flight tests at the Bell test facility, the aircraft was moved to Ames Research Center in Sunnyvale, California, where it was then mounted in the large Ames wind tunnel and tested extensively in various simulated flight environments. |
||
For the [[United States Department of Defense|U.S. Department of Defense]] Joint-service Vertical take-off/landing Experimental (JVX) aircraft program, Bell Helicopter and [[Boeing Rotorcraft Systems|Boeing Vertol]] teamed to submit a bid for an enlarged version of the XV-15 in 1983. The Bell Boeing team received a preliminary design contract that year, which led to the [[Bell Boeing V-22 Osprey]].<ref name="Norton_p22-33">Norton 2004, pp. 22–33.</ref> |
For the [[United States Department of Defense|U.S. Department of Defense]] Joint-service Vertical take-off/landing Experimental (JVX) aircraft program, Bell Helicopter and [[Boeing Rotorcraft Systems|Boeing Vertol]] teamed to submit a bid for an enlarged version of the XV-15 in 1983. The Bell Boeing team received a preliminary design contract that year, which led to the [[Bell Boeing V-22 Osprey]].<ref name="Norton_p22-33">Norton 2004, pp. 22–33.</ref> |
||
Line 70: | Line 73: | ||
Following wind tunnel and flight testing by Bell, the aircraft was then moved to [[Dryden Flight Research Center|NASA Dryden]], which is at Edwards Air Force Base in the California High Desert. The XV-15 flight testing continued expanding its flight envelope. It was able to successfully operate in both helicopter and normal aircraft flight modes and smoothly transition between the two. Once the aircraft was considered sufficiently tested, it was returned to Ames Research Center for further testing. |
Following wind tunnel and flight testing by Bell, the aircraft was then moved to [[Dryden Flight Research Center|NASA Dryden]], which is at Edwards Air Force Base in the California High Desert. The XV-15 flight testing continued expanding its flight envelope. It was able to successfully operate in both helicopter and normal aircraft flight modes and smoothly transition between the two. Once the aircraft was considered sufficiently tested, it was returned to Ames Research Center for further testing. |
||
The XV-15s were deemed sufficiently tested, and one aircraft was taken to the 1981 [[Paris Air Show]] for demonstration flights. The New York Times praised its performance. "And if ever there was a lovable plane, it is the Bell XV-15... The machine, the hit of the show, performed a series of maneuvers including bowing to the crowd."<ref>https://www.nytimes.com/1981/06/14/business/the-paris-airshow-wining-dining-and-dealing-for-military-might.html?pagewanted=2</ref> Over the next year, Senator Barry Goldwater, Navy Secretary John Lehman, and other officials were offered guest co-piloting flights to promote tiltrotor technology for military development.<ref>R. Whittle, ''The Dream Machine''. pp. 95–100.</ref> |
The XV-15s were deemed sufficiently tested, and one aircraft was taken to the 1981 [[Paris Air Show]] for demonstration flights. The ''[[The New York Times|New York Times]]'' praised its performance. "And if ever there was a lovable plane, it is the Bell XV-15... The machine, the hit of the show, performed a series of maneuvers including bowing to the crowd."<ref>{{Cite news|url=https://www.nytimes.com/1981/06/14/business/the-paris-airshow-wining-dining-and-dealing-for-military-might.html?pagewanted=2|title = The Paris Airshow: Wining, Dining and Dealing for Military Might|newspaper = The New York Times|date = 14 June 1981|last1 = Anderson|first1 = Susan Heller}}</ref> Over the next year, Senator Barry Goldwater, Navy Secretary John Lehman, and other officials were offered guest co-piloting flights to promote tiltrotor technology for military development.<ref>R. Whittle, ''The Dream Machine''. pp. 95–100.</ref> |
||
The XV-15s were a standard demonstration in the annual summer airshow at the co-located [[Moffett Federal Airfield|Moffett Field Naval Air Station]] for several years during the 1980s. Both XV-15s were flown actively throughout the 1980s testing aerodynamics and tiltrotor applications for civilian and military aircraft types that might follow |
The XV-15s were a standard demonstration in the annual summer airshow at the co-located [[Moffett Federal Airfield|Moffett Field Naval Air Station]] for several years during the 1980s. Both XV-15s were flown actively throughout the 1980s testing aerodynamics and tiltrotor applications for civilian and military aircraft types that might follow. |
||
The [[Fédération Aéronautique Internationale]] classifies the XV-15 as a Rotodyne, and as such it holds the speed record of {{convert|456|kph}},<ref>"[http://www.fai.org/fai-record-file/?recordId=1553 FAI Record ID #1553] {{webarchive|url=https://web.archive.org/web/20131203032031/http://www.fai.org/fai-record-file/?recordId=1553 |date=2013-12-03 }}" ''[[Fédération Aéronautique Internationale]]'' Record date 6 April 1990. Accessed: 18 November 2013.</ref> and the 3 km<ref>"[http://www.fai.org/fai-record-file/?recordId=1551 FAI Record ID #1551 - Rotodyne, Time to climb to a height of 3000 m] {{webarchive|url=https://web.archive.org/web/20131203035628/http://www.fai.org/fai-record-file/?recordId=1551 |date=2013-12-03 }}" ''[[Fédération Aéronautique Internationale]]'' Record date 15 March 1990. Accessed: 18 November 2013.</ref> and 6 km time-to-climb.<ref>"[http://www.fai.org/fai-record-file/?recordId=1552 FAI Record ID #1552 - Rotodyne, Time to climb to a height of 6000 m] {{webarchive|url=https://web.archive.org/web/20131203044149/http://www.fai.org/fai-record-file/?recordId=1552 |date=2013-12-03 }}" ''[[Fédération Aéronautique Internationale]]'' Record date 15 March 1990. Accessed: 18 November 2013.</ref> <!--still holds several others: http://www.fai.org/fai-record-file/?recordId=1549 , http://www.fai.org/fai-record-file/?recordId=1550 , http://www.fai.org/fai-record-file/?recordId=1553 , http://www.fai.org/fai-record-file/?recordId=1554 . Use Rotodyne as search name --> |
The [[Fédération Aéronautique Internationale]] classifies the XV-15 as a Rotodyne, and as such it holds the speed record of {{convert|456|kph}},<ref>"[http://www.fai.org/fai-record-file/?recordId=1553 FAI Record ID #1553] {{webarchive|url=https://web.archive.org/web/20131203032031/http://www.fai.org/fai-record-file/?recordId=1553 |date=2013-12-03 }}" ''[[Fédération Aéronautique Internationale]]'' Record date 6 April 1990. Accessed: 18 November 2013.</ref> and the 3 km<ref>"[http://www.fai.org/fai-record-file/?recordId=1551 FAI Record ID #1551 - Rotodyne, Time to climb to a height of 3000 m] {{webarchive|url=https://web.archive.org/web/20131203035628/http://www.fai.org/fai-record-file/?recordId=1551 |date=2013-12-03 }}" ''[[Fédération Aéronautique Internationale]]'' Record date 15 March 1990. Accessed: 18 November 2013.</ref> and 6 km time-to-climb.<ref>"[http://www.fai.org/fai-record-file/?recordId=1552 FAI Record ID #1552 - Rotodyne, Time to climb to a height of 6000 m] {{webarchive|url=https://web.archive.org/web/20131203044149/http://www.fai.org/fai-record-file/?recordId=1552 |date=2013-12-03 }}" ''[[Fédération Aéronautique Internationale]]'' Record date 15 March 1990. Accessed: 18 November 2013.</ref> <!--still holds several others: http://www.fai.org/fai-record-file/?recordId=1549 , http://www.fai.org/fai-record-file/?recordId=1550 , http://www.fai.org/fai-record-file/?recordId=1553 , http://www.fai.org/fai-record-file/?recordId=1554 . Use Rotodyne as search name --> |
||
===Further testing=== |
===Further testing=== |
||
[[File: |
[[File:XV-15 Paris 1980.jpg|thumb|XV-15 N702NA at the 1981 Paris Air Show]] |
||
The first XV-15 prototype aircraft, N702NA, was transferred back to Bell for company development and demonstration use. On 20 August 1992, the aircraft crashed while being flown by a guest test pilot. He was lifting off for a final hover when a bolt slipped out of the collective control system on one pylon, causing that rotor to go to full pitch. The aircraft rolled upside down out of control and crashed inverted. While significantly damaged, the aircraft was largely structurally intact and both the pilot and copilot escaped with only minor injuries from the crash. The cockpit of the aircraft was salvaged and converted for use as a [[flight simulator]]. |
The first XV-15 prototype aircraft, N702NA, was transferred back to Bell for company development and demonstration use. On 20 August 1992, the aircraft crashed while being flown by a guest test pilot. He was lifting off for a final hover when a bolt slipped out of the collective control system on one pylon, causing that rotor to go to full pitch. The aircraft rolled upside down out of control and crashed inverted. While significantly damaged, the aircraft was largely structurally intact and both the pilot and copilot escaped with only minor injuries from the crash. The cockpit of the aircraft was salvaged and converted for use as a [[flight simulator]]. |
||
The second XV-15 prototype, N703NA, was used for tests |
The second XV-15 prototype, N703NA, was used for tests supporting the military V-22 Osprey program and [[AgustaWestland AW609|Bell/Agusta BA609]] civilian transport (still under development in 2023 as the AgustaWestland AW609). It continued in primarily NASA test operations until September 2003. The shortest takeoff distance was achieved with the nacelles at 75 degrees angle.<ref name=NASA_SP-2000-4517>Maisel 2000, p. 70.</ref> |
||
After N703NA was retired from test operations, it was donated to the Smithsonian [[National Air and Space Museum]] in Washington, D.C. The XV-15 was flown cross-country from Fort Worth, Texas to the museum before being decommissioned for display. It is now on display at the [[Steven F. Udvar-Hazy Center]] at [[Washington Dulles International Airport]]. |
After N703NA was retired from test operations, it was donated to the Smithsonian [[National Air and Space Museum]] in Washington, D.C. The XV-15 was flown cross-country from Fort Worth, Texas to the museum before being decommissioned for display. It is now on display at the [[Steven F. Udvar-Hazy Center]] at [[Washington Dulles International Airport]]. |
||
Line 88: | Line 91: | ||
[[File:Bell XV-15 line drawing.png|right|350px]] |
[[File:Bell XV-15 line drawing.png|right|350px]] |
||
[[File:Bell XV-15 tilt rotor research aircraft.png|title=Cutaway drawing|right|350px]] |
[[File:Bell XV-15 tilt rotor research aircraft.png|title=Cutaway drawing|right|350px]] |
||
{{External media |topic=|width= | |
{{External media |topic=|width= |float=right |
||
|image1=[[Cutaway drawing]] of [http://www.flightglobal.com/airspace/media/experimentalaircraftcutaways/images/8965/bell-xv-15-cutaway.jpg XV-15 ] }} |
|image1=[[Cutaway drawing]] of [http://www.flightglobal.com/airspace/media/experimentalaircraftcutaways/images/8965/bell-xv-15-cutaway.jpg XV-15 ] }} |
||
{{Aircraft specs |
|||
|ref=Jane's All the World's Aircraft 1988-89<ref name=JAWA88-89>{{cite book |title=Jane's All the World's Aircraft 1988-89 |editor1-last=Taylor |editor1-first=John W.R. |year=1988 |publisher=Jane's Information Group |location=London |isbn=0-7106-0867-5 |edition=79th |pages=347–348}}</ref> |
|||
{{aircraft specifications |
|||
|prime units?=kts |
|||
<!-- if you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] --> |
|||
<!-- |
|||
|plane or copter?=copter <!-- options: plane/copter --> |
|||
General characteristics |
|||
|jet or prop?=prop <!-- options: jet/prop/both/neither --> |
|||
<!-- Now, fill out the specs. Please include units where appropriate (main comes first, alt in parentheses). If an item doesn't apply leave it blank. For instructions on using |more general=, |more performance=, |power original=, and |thrust original= see [[Template talk:Aircraft specifications]]. |
|||
--> |
--> |
||
|crew=2 on Rockwell-Columbus LW-3B [[ejection seat]]s |
|||
|ref=NASA SP-2000-4517<ref>Maisel 2000, pp. 130–132.</ref> |
|||
|capacity=up to 9 passengers if seats fitted / {{cvt|3400|lb|0}} max. payload STOL |
|||
|crew= two (pilot, copilot) |
|||
|length ft= |
|||
|capacity= |
|||
|length |
|length in=505 |
||
|length |
|length note= |
||
|span ft= |
|||
* '''Wingspan:''' 57 ft 2 in (17.42 m) with turning rotors |
|||
|span |
|span in= |
||
|span |
|span note= |
||
| |
|width ft=57 |
||
|width in=2 |
|||
|height main= 12 ft 8 in |
|||
|width note=overall with rotors turning |
|||
|height alt= 3.86 m |
|||
|height ft=12 |
|||
|area main= <!--ft²--> |
|||
|height in=8 |
|||
|area alt= <!--m²--> |
|||
|height note=over tail fins |
|||
|airfoil=NACA 64A015 |
|||
::::{{cvt|15|ft|4|in|0}} with nacelles vertical |
|||
|empty weight main= 10,083 lb |
|||
|wing area sqft=169 |
|||
|empty weight alt= 4,574 kg |
|||
|wing area note= |
|||
|loaded weight main= <!--lb--> |
|||
|aspect ratio= |
|||
|loaded weight alt= <!--kg--> |
|||
|airfoil='''Wings''' - [[NACA airfoil|NACA 64A015]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref> |
|||
|useful load main= <!--lb--> |
|||
|empty weight lb=9570 |
|||
|useful load alt= <!--kg--> |
|||
| |
|empty weight note= |
||
| |
|gross weight lb=13000 |
||
|gross weight note=VTO |
|||
|more general= '''Engine power ratings:''' |
|||
|max takeoff weight lb=15000 |
|||
** 1,550 shp (1,156 kW) normal takeoff power (10 min max) |
|||
|max takeoff weight note=STO |
|||
** 1,802 shp (1,354 kW) emergency power (2 min max) |
|||
|fuel capacity={{cvt|229|USgal|impgal l|0}} in four wing tanks |
|||
<!--*'''Rotor diameter:''' 25 ft (7.62 m)--> |
|||
|more general= |
|||
* '''Fuel weight:''' 1,436 lb (651 kg) |
|||
<!-- |
|||
Powerplant |
|||
--> |
|||
|eng1 number=2 |
|||
|eng1 name=[[Textron Lycoming LTC1K-4K]] |
|||
|eng1 type=[[turboshaft]] / [[turboprop]] engines |
|||
|eng1 shp=1550 |
|||
|eng1 note=normal takeoff power (10 min max)<ref>Maisel 2000, pp. 130–132.</ref> |
|||
::::{{cvt|1802|shp|0}} emergency power (2 min max) |
|||
:::: (modified Lycoming T53-L-13B) |
|||
|rot number=2 |
|||
|engine (prop)=Avco Lycoming LTC1K-4K (modified [[Lycoming T53|T53-L-13B]]) |
|||
|rot dia ft=25 |
|||
|type of prop=turboshaft engine |
|||
|rot dia in=<!-- helicopters --> |
|||
|number of props=2 |
|||
|rot area sqft=981.8 |
|||
|power main= 1,550 shp |
|||
|rot area note=total<br> |
|||
|power alt= 1,156 kW |
|||
*'''Blade section (original):''' - '''root:''' [[NACA airfoil|NACA 64-935/528/118]]; '''tip:''' [[NACA airfoil|NACA 64-(1.5)12/208]]<ref name="Selig"/> |
|||
|power original= |
|||
*'''Blade section (Boeing ATB):''' - '''root:''' V43030-1.58/VR-7; '''tip:''' Boeing VR-8<ref name="Selig"/> |
|||
<!-- |
|||
Performance |
|||
--> |
|||
|max speed kts=332 |
|||
|max speed note=at {{cvt|17000|ft|0}} |
|||
|max speed mach=<!-- supersonic aircraft --> |
|||
|cruise speed kts=303 |
|||
|cruise speed note=max. at {{cvt|16500|ft|0}} |
|||
::::{{cvt|200|kn|mph km/h|0}} at {{cvt|20000|ft|0}} |
|||
|stall speed kts= |
|||
|stall speed note= |
|||
|never exceed speed kts=364 |
|||
|never exceed speed note= |
|||
|minimum control speed kts= |
|||
|minimum control speed note= |
|||
|range nmi=445 |
|||
|range note=with maximum fuel |
|||
|combat range nmi= |
|||
|combat range note= |
|||
|ferry range nmi= |
|||
|ferry range note= |
|||
|endurance=<!-- if range unknown --> |
|||
|ceiling ft=29000 |
|||
|ceiling note=<br> |
|||
*'''Service ceiling OEI:''' {{cvt|15000|ft|0}} |
|||
*'''Hover ceiling IGE:''' {{cvt|10500|ft|0}} |
|||
*'''Hover ceiling OGE:''' {{cvt|8650|ft|0}} |
|||
|g limits=<!-- aerobatic --> |
|||
|roll rate=<!-- aerobatic --> |
|||
|glide ratio=<!-- sailplanes --> |
|||
|climb rate ftmin=3150 |
|||
|climb rate note=at sea level |
|||
|time to altitude= |
|||
|sink rate ftmin=<!-- sailplanes --> |
|||
|sink rate note= |
|||
|lift to drag= |
|||
|wing loading lb/sqft= |
|||
|wing loading note= |
|||
|disk loading lb/sqft=15.2 |
|||
|disk loading note= |
|||
|fuel consumption lb/mi= |
|||
|power/mass={{cvt|0.45|hp/lb|0}}<ref name=wickTilt>{{cite journal |last1=Warwick |first1=Graham |title=Tilting at targets |journal=Flight International |date=February 1992 |page=44}}</ref><!--url inactive. when flight archive re-opens unlikely to be the same--> |
|||
|thrust/weight= |
|||
|max speed main= 300 knots |
|||
|max speed alt= 345 mph, 557 km/h |
|||
|cruise speed main= <!--knots--> |
|||
|cruise speed alt= <!--mph, km/h--> |
|||
|never exceed speed main= <!--knots--> |
|||
|never exceed speed alt= <!--mph, km/h--> |
|||
|stall speed main= 100 knots when in airplane mode |
|||
|stall speed alt= 115 mph, 185 km/h |
|||
|range main= 445 nmi |
|||
|range alt= 515 mi, 825 km |
|||
|ceiling main= 29,500 ft |
|||
|ceiling alt= 8,840 m |
|||
|climb rate main= <!--ft/min--> |
|||
|climb rate alt= <!--m/s--> |
|||
|loading main= 13.2 lb/ft<sup>2</sup> |
|||
|loading alt= 73 kg/m<sup>2</sup><ref name=wickTilt>Warwick, Graham. "[http://www.flightglobal.com/pdfarchive/view/1992/1992%20-%200262.html Tilting at targets]" page 44 ''[[Flight International]]'', February 1992. Accessed: 4 January 2014.</ref> |
|||
|thrust/weight= <!--a unitless ratio--> |
|||
|power/mass main= <!--hp/lb--> |
|||
|power/mass alt= <!--W/kg--> |
|||
|more performance= |
|more performance= |
||
*'''Power loading:''' 1.35 kg/kW<ref name=wickTilt/> |
|||
* '''Hovering altitude:''' 8,800 ft (2,635 m) out of ground effect |
|||
|armament= |
|||
|avionics= |
|avionics= |
||
}} |
}} |
||
Line 167: | Line 201: | ||
|similar aircraft= |
|similar aircraft= |
||
* [[Canadair CL-84]] |
* [[Canadair CL-84 Dynavert]] |
||
* [[Sikorsky S-69]] |
* [[Sikorsky S-69]] |
||
* [[Sikorsky S-72]] |
* [[Sikorsky S-72]] |
![]() |
This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)
|
XV-15 | |
---|---|
![]() | |
XV-15 in a hover | |
Role | Experimental VTOL aircraft
Type of aircraft
|
National origin | United States |
Manufacturer | Bell Helicopter Textron |
First flight | 3 May 1977 |
Retired | 2003 |
Status | Prototype |
Primary user | NASA |
Number built | 2 |
Developed into | V-22 Osprey AgustaWestland AW609 |
The Bell XV-15 is an American tiltrotor VTOL aircraft. It was the second successful experimental tiltrotor aircraft and the first to demonstrate the concept's high speed performance relative to conventional helicopters.
The idea of building VTOL aircraft using helicopter-like rotors at the wingtips originated in the 1930s. The first design resembling modern tiltrotors was patented by George Lehberger in May 1930, but he did not develop the concept further. In World War II, a German prototype called the Focke-Achgelis Fa 269 was developed starting in 1942, but it never flew.
Two prototypes that made it to flight were the one-seat Transcendental Model 1-G and two-seat Transcendental Model 2, both powered by single reciprocating engines. Development started on the Model 1-G in 1947, and it flew in 1954. The Model 1-G flew until a crash in Chesapeake Bay on 20 July 1955, destroying the prototype aircraft but not seriously injuring the pilot. The Transcendental 1-G was the first tiltrotor aircraft to have flown, and it accomplished most of a helicopter-to-aircraft transition in flight to within ten degrees of true horizontal aircraft flight. The Model 2 was developed and flew shortly afterward, but it did not fly much beyond hover tests. The United States Air Force withdrew funding in favor of the Bell XV-3.
The Bell XV-3 was first flown in 1955. Like its predecessors, the XV-3 had the engines in the fuselage and driveshafts transferring power out to tilting wingtip rotor assemblies.
Other rotor concepts, such as slowed rotors, stopped rotors, folding rotors, and variable-diameter rotors, were investigated for subsequent designs, but Bell engineers Kenneth Wernicke and Bob Lichten deemed them unfeasible compared to experience with the XV-3 project.[1]
One of the major problems with the early tiltrotor aircraft designs was that the driveshafts carrying power from the fuselage out to the wingtip rotors, along with the gearbox and tilting mechanisms at the wingtips, had substantial loads placed upon them and were heavy. They were transferring large amounts of power and torque long distances for an aircraft power transmission system.
The XV-15 experimental aircraft introduced a major design concept advance: instead of engines in the fuselage, the XV-15 moved the engines out to the rotating wingtip pods, directly coupled to the rotors. The normal path for power was directly from the engine into a speed-reduction gearbox and into the rotor/propeller without any long shafts involved. There was still a driveshaft along the wings for emergency use to transfer power to the opposite rotor in case of engine failure, but that shaft did not normally carry any power loads, allowing it to be lighter.
The tilting engine concept introduced complexities in the design of the engines and engine pods to be able to shift from operating horizontally to operating vertically. Those problems were addressed fairly early in the XV-15 program.
In the late 1960s and early 1970s, NASA and other researchers worked extensively on theoretical and wind tunnel tests of various rotor pods. Two companies were involved in the research and proposing designs: Bell Helicopter and Boeing Vertol. The focus was on tilt-rotor pods, integration of the tilting rotors with the wings and fuselage of the aircraft, and studying the airflow as the rotors tilted. Tilt rotors with fixed rotors and with folding rotors were investigated.
What was to become the XV-15 program was launched in 1971 at NASA Ames Research Center. After preliminary work, a competition was held to award two $0.5 million research and development contracts for prototype designs. Companies that responded included Sikorsky Aircraft, Grumman Aircraft, Boeing Vertol, and Bell Helicopter.
R&D contracts were issued to Bell Helicopter and Boeing Vertol on 20 October 1972. The two companies' design proposals were delivered on 22 January 1973.
Boeing Vertol proposed its Model 222 (not to be confused with the later Bell 222 conventional helicopter), in which the engines were in fixed pods at the end of each wing, and a small, rotating pod with the rotor was slightly closer to the fuselage on the wing. This design simplified the engine design by keeping it horizontal at all times without having very long driveshafts to the tilting rotors.
In the Bell design, Bell Model 301, the whole wingtip pod rotated between horizontal and vertical, with the engine and rotor assembly fixed together within the pod. This simplified the power transmission, but it had more complicated requirements for the engine design and was probably slightly heavier than the Boeing proposal.
After a review of both proposals, NASA selected the Bell 301 for further development, and a contract for further R&D was issued on 31 July 1973. Extensive engineering and testing took the next four years to complete the development of the aircraft. The first of two Bell XV-15s, tail number N702NA, first flew on 3 May 1977. After minimal flight tests at the Bell test facility, the aircraft was moved to Ames Research Center in Sunnyvale, California, where it was then mounted in the large Ames wind tunnel and tested extensively in various simulated flight environments.
For the U.S. Department of Defense Joint-service Vertical take-off/landing Experimental (JVX) aircraft program, Bell Helicopter and Boeing Vertol teamed to submit a bid for an enlarged version of the XV-15 in 1983. The Bell Boeing team received a preliminary design contract that year, which led to the Bell Boeing V-22 Osprey.[2]
Following wind tunnel and flight testing by Bell, the aircraft was then moved to NASA Dryden, which is at Edwards Air Force Base in the California High Desert. The XV-15 flight testing continued expanding its flight envelope. It was able to successfully operate in both helicopter and normal aircraft flight modes and smoothly transition between the two. Once the aircraft was considered sufficiently tested, it was returned to Ames Research Center for further testing.
The XV-15s were deemed sufficiently tested, and one aircraft was taken to the 1981 Paris Air Show for demonstration flights. The New York Times praised its performance. "And if ever there was a lovable plane, it is the Bell XV-15... The machine, the hit of the show, performed a series of maneuvers including bowing to the crowd."[3] Over the next year, Senator Barry Goldwater, Navy Secretary John Lehman, and other officials were offered guest co-piloting flights to promote tiltrotor technology for military development.[4]
The XV-15s were a standard demonstration in the annual summer airshow at the co-located Moffett Field Naval Air Station for several years during the 1980s. Both XV-15s were flown actively throughout the 1980s testing aerodynamics and tiltrotor applications for civilian and military aircraft types that might follow.
The Fédération Aéronautique Internationale classifies the XV-15 as a Rotodyne, and as such it holds the speed record of 456 kilometres per hour (283 mph),[5] and the 3 km[6] and 6 km time-to-climb.[7]
The first XV-15 prototype aircraft, N702NA, was transferred back to Bell for company development and demonstration use. On 20 August 1992, the aircraft crashed while being flown by a guest test pilot. He was lifting off for a final hover when a bolt slipped out of the collective control system on one pylon, causing that rotor to go to full pitch. The aircraft rolled upside down out of control and crashed inverted. While significantly damaged, the aircraft was largely structurally intact and both the pilot and copilot escaped with only minor injuries from the crash. The cockpit of the aircraft was salvaged and converted for use as a flight simulator.
The second XV-15 prototype, N703NA, was used for tests supporting the military V-22 Osprey program and Bell/Agusta BA609 civilian transport (still under development in 2023 as the AgustaWestland AW609). It continued in primarily NASA test operations until September 2003. The shortest takeoff distance was achieved with the nacelles at 75 degrees angle.[8]
After N703NA was retired from test operations, it was donated to the Smithsonian National Air and Space Museum in Washington, D.C. The XV-15 was flown cross-country from Fort Worth, Texas to the museum before being decommissioned for display. It is now on display at the Steven F. Udvar-Hazy CenteratWashington Dulles International Airport.
External image | |
---|---|
![]() |
Data from Jane's All the World's Aircraft 1988-89[9]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
Related lists
Bell Aircraft and Bell Helicopter/Bell Textron aircraft
| |
---|---|
Manufacturer designations |
|
Fighter aircraft |
|
Target drones |
|
Attack helicopters |
|
Observation and utility helicopters |
|
Commercial helicopters |
|
Tiltrotors |
|
UAVs |
|
Non-production helicopters |
|
Experimental aircraft |
|
Names |
|
1 Unknown/not assigned |
| |
---|---|
Original sequence (1954-1962) |
|
Tri-service sequence (1962-present) |
|
1 Not assigned • 2 Assigned to multiple types • 3 Unofficial |