THE TECHNICAL ASPECTS OF THE TRANSFER OF FUEL TO A TIP MOUNTED RAMJET ENGINE COMBUSTION CHAMBER

The Hiller-Hornet, now designated by the Military as the HOE-1/YH-32 model helicopter, is a ramjet powered helicopter with the engines mounted on the tips of the main rotor blades. As such, considerable time has been expended on the design of the fuel system required to transfer the fuel to these remotely located engines. A photograph of the subject helicopter is shown as Figure No. 1. This ship is an outgrowth of the original XHJ-1 models first flown in August 1950 and used for some months after that as a "flying test stand" for ramjet engine development. During the period since that time considerable testing of engines and connected systems has been accomplished. To date some 460 hours of flight test work, over 1,500 hours of whirl testing, and more than 1,500 static tests have been run. This program has brought to light many problems which are associated either directly or indirectly with the fuel system, and these problems and their solutions are the subject of this paper. The problem at hand, of course, deals with the idiosyncrasies of transferring fuel from the fuel tanks to the engine combustion chamber in such a way that adequate control of the engine under all flight conditions is possible. In this instance, the discussion will be confined specifically to the Hiller-Hornet helicopter although much of the information is of a general nature. Maximum consideration will be given to the technical aspects of the problem and not to the specific problems of fuel pump design, valve choices, etc., although some of the more difficult parts of the design problem may be touched upon.