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MC
DONNELL
Mc
DONNELL XHJD-1 |
|
En
búsqueda de trabajo para su novata compañía, James McDonnell estaba
preparado a considerar cualquier alternativa lógica y hasta en
arriesgar algo de dinero a cambio de adquirir conocimientos en nueva
tecnología, tal como en la de las aeronaves con alas rotativas. Para
esto se contactó con la compañía Platt-LePage Aircraft a mediados de
1942, y un año mas tarde, autorizó a Constantine M. Zakhartchenko y un
pequeño grupo de ingenieros a emprender la investigación, diseño y
construcción de rotores. En
compensación, se le permitió a McDonnell enviar a algunos ingenieros
para unirse al equipo de Platt-LePage para aprender las técnicas de
ingeniería de los helicópteros. Por otra parte, se le permitió
trabajar sobre un requerimiento de un helicóptero de dos motores y dos
rotores encargados por el Ejército. Aunque este desarrollo no llegó a
buen puerto en la competencia del Army (se seleccionó al Kellet
XR-10), a cambio se incrementó su investigación, obteniendo de
Platt-LePage un contrato para que McDonnell Aircraft Corporation
iniciara un desarrollo paralelo de un concepto de rotor doble con dos
motores. Como plataforma de investigación se propuso el MODELO 65,
el cual se usaría para el estudio
de los efectos del rotor, la carga del disco, la variación del
flapeo de las palas y otras variables. Considerando
la disposición del rotor lado a lado propuesto por McDonnell, sería el
helicóptero operando en el rol de lucha antisubmarina mas grande del
momento, el Departamento de Aeronáutica firmó una carta de intención
el 15 de mayo de 1944, cubriendo el diseño, construcción y prueba de
un XHJD-1. Esta carta de intención fue confirmada el 23 de marzo
de 1945 por un contrato. El 27 de abril de 1946, en el aeropuerto
Lambert Field, de St Louis se realizó el primer vuelo en estacionario. Diseñado
para transportar hasta 10 ocupantes, voló con dos plazas y 816 Kg. de
equipamiento de instrumentos de pruebas, el Whirlaway estaba
adaptado con dos rotores lado a lado montados sobre unos pilones hacia
fuera de las nacelas de los motores. Los motores eran unos Pratt &
Whitney R-985-AN-14B de 7 cilindros radiales de 450hp, montados sobre
unas pequeñas alas. Desde abril
de 1946 hasta junio de 1951, el XHJD-1 fue usado para diferentes
vuelos de prueba, incluidos la evaluación de perfomance, estabilidad y
vibración. En este proceso el Whirlaway, que constaba de un diámetro
de rotor de 15,24 m fue reemplazado por diferentes tipos de rotores de
varios diámetros, además de reforzársele la cola. Pero debido a que
en este periodo, la tecnología e investigación en la rama de los helicópteros
había avanzado bastante, ni el XHJD-1 o el Modelo 65C entraron
en producción. Hasta la finalización de las pruebas, el XHJD-1 fue
el primer helicóptero en llevar el nombre de
McDonnell como el primer helicóptero bimotor exitoso. Fue donado
al National Air and Space Museum. |
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In seeking to find work for his fledgling company, James
McDonnell was prepared to consider all logical alternatives and was
willing to risk some capital to acquire know-how in new technology such
as that required to develop rotary wing aircraft. To that end, he first
made a small investment in the Platt-LePage Aircraft Company in mid-1942
and, a year later, he authorized Constantine M. Zakhartchenko and a
small group of engineers to undertake research on design and
construction of rotors. In return for his initial investment, McDonnell was
allowed to have some of his engineers join the Platt-LePage design team
to learn the techniques of helicopter engineering. Moreover, he was
appraised of Platt-LePage's preliminary work on a twin-engined,
twin-rotor helicopter to meet Army requirements. Although that design
eventually proved unsuccessful in the Army competition (the AAF selected
the Kellet XR-10), it fared better in a different guise as
McDonnell, in return for an increase in his investment as finalized in
June 1944, obtained Platt-LePage's agreement allowing the McDonnell
Aircraft Corporation to initiate the parallel development of the
twin-engined, twin-rotor concept. On the strength of both this agreement
and the work accomplished by Zakhartchenko's team, McDonnell proposed a
helicopter of this design to the Navy to serve either as a testbed or as
an anti-submarine warfare platform. As a testbed, the proposed Model
65 was intended to be used for the study of the effects of rotor
diameter, disk loading, variations in rotor blade flap and lag angles,
and other variables. In the ASW role, it was to be able to carry an
adequate load of detection gear and weapons. Considering the side-by-side rotor arrangement
proposed by McDonnell to be a most suitable configuration for large
helicopters capable of operating in the ASW role, the Bureau of
Aeronautics issued a Letter of Intent on 15 May, 1944, covering the
design, construction, and testing of one XHJD-1. This Letter of
Intent was confirmed on 23 March, 1945, when Contract NOa(s)-3703 was
awarded. At the time of contract award, design of the Whirlaway,
entrusted to a team led by Constantine Zakhartchenko, was well underway
and ground testing was begun early in 1946. Piloted by Charles R. Wood
Jr, the XHJD-1 made its first hover flight at Lambert Field, St
Louis, on 27 April, 1946. Designed to carry up to ten occupants but normally
flown as a two-seater with up to 816kg of test instrumentation, the Whirlaway
was fitted with twin side-by-side rotors mounted on pylons extending
outboard of the engine nacelles. The nacelles, each housing a 450hp
Pratt & Whitney R-985-AN-14B seven-cylinder radial engine, were
attached to short wings which supported approximately 10 per cent of the
gross weight during cruise and as much as 30 per cent of the weight in
power-off autorotation, with consequent substantial improvement in
overall performance efficiency. Furthermore, this feature, combined with
the ability to transmit power from either engine to both rotors by
transmissions and gear boxes, enabled the XHJH-1 to maintain
level flight at full gross weight on the power of only one engine. From April 1946 until June 1951, the XHJD-1
was used for numerous flying research tests including the evaluation of
performance, stability balance and vibration characteristics peculiar to
its twin-rotor configuration. In the process, the Whirlaway had
its original 15.24-m diameter rotors replaced by rotors of varying
diameters and had a braced tailplane with externally balanced control
surfaces added before translation flights began. Once vibration and
resonance problems with its unsynchromzed three-blade rotors were
alleviated through the use of shock-absorbing rotor mounts, the XHJD-1
was considered to handle well and was flown some 250 hours without
serious mishap In the process, it was flown not only by McDonnell and
Navy pilots but after being fitted with a rescue winch, was also
evaluated in November 1949 by USAF pilots from the Arctic Rescue
Helicopter Board. However, as helicopter technology had made significant
progress since development of the Whirlaway had been initiated,
neither the XHJD-1 nor its proposed Model 65C development
was put into production. Upon completion of its trials programme, the XHJD-1
- the first helicopter to bear the McDonnell name and the world's first
successful twin-engined, twin-rotor helicopter was donated to the
National Air and Space Museum. Rene J. Francillon "McDonnell Douglas Aircraft since 1920: Volume II", 1997 |
|
Characteristics |
Information |
Characteristics |
Information |
First
Flight Primer Vuelo |
1946 |
Engine Motor |
2
P&W R-985 |
Seating
Capacity Plazas |
2 / 10 |
Power Potencia |
450 HP each |
Empty
Weight Peso Vacío |
3629 Kg |
Hover
Ceiling O.G.E. Estacionario O.G.E |
Mt |
Maximum
Weight Peso Máximo |
4990 Kg |
Hover
Ceiling I.G.E. Estacionario I.G.E |
Mt |
Vel.
Cruise Vel. crucero |
80 Kts |
Service
Ceiling Techo de Servicio |
3930 Mt |
V.N.E. V.N.E |
100 Kts |
Maximum
Range (Std) Alcance (Std) |
260 NM |
Dimensions / Dimensiones |
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Total
Length Largo Total |
32,15 Ft |
Main
Rotor Diameter Diam. Rotor Principal |
46,06 / 50,0 Ft |
Total
Height Alto Total |
12,23 Ft |
Tail
Rotor Diameter Diam. Rotor de Cola |
NA |
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