AGMA 90FTM7-1990 pdf free.Advanced Rotorcraft Transmission Program – A Status Review.
AIRCRAFT SELECTION
The Boeing Helicopters aircraft selection for this program was a Tactical Tilt Rotor (TTR) aircraft which met the requirements outlined for the FAAV (nominal gross weight of 10,000 to 20,000 pounds). The TTR is a small lightweight attack tilt rotor aircraft designed to be highly maneuverable and survivable. It is also applicable to counter air attack and air-ta-air combat missions. Its primary mission gross weight is about 17,223 pounds.
In general the Tr’R drive system arrangement is similar to that of the V-22 Osprey aircraft. It s a twin engine configuration (see Figure 1) with one engine mounted In each wing tip nacelle and pivots with the rotors as on the V.22 aircraft. The engine size is in the 2480 SHP class. A candidate engine for this size was a growth derivative of the T700-701C. Some additional characteristics pertinent to the ART effort are given in Table I and Figure 2. Interconnect cross shafting is also required between the rotors and engines so that one engine may drive both rotors in the event of an engine failure. Specifics of accessory drives, APU, and details of the lube system (and cooling) are being developed and the transmissions will be designed to provide for 30 mInutes of operation after lube loss or gear/shaft damage. In general all subsystems of the TTR will provide both crashworthy and damage tolerant characteristics.
TRADE STUDIES
In order to evaluate the effect of Advanced Technology improvements on aircraft size and performance, computer programs were initially used to develop the reference aircraft design. In the early stage of this program a few key parameters were used to develop the drive system design. As the design progressed, detailed rotor and engine performance data were entered to improve the precision of the calculations. The program was used to discover broad trends early in the design process and it was also used to determine the effect of relatively small modifications once the design is more developed.
During the early development of the ART drive system, comparisons and trade studies were conducted between novel transmission configurations with high payoff potential. In addition to the configuration, advance technology features such as high temperature materials, novel gear and bearing designs, composites, and lubrication methods were also evaluated in achieving the goals of the ART Program. The Boeing Helicopters approach included the study of the following transmission configurations:
1. Selfaligning Beanngless Planetary (SABP) Configuration The basic attributes of this configuration was the elimination of planet carriers and bearings and the static gear load cancellation through aligned gear meshes.
2. SplIt Torque Configuration – The basic attributes of this configuration was the multiple parallel torques load paths which provided design/flexibility in optimizing the gear mesh loads.AGMA 90FTM7 pdf download.