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Aviation History
1962
1962 - 2074.PDF
FLIGHT International, 13 September 1962 trolled by the pilot are supplied with a greater amount of bleed air than those controlled by the variable-stability system, the pilot has a direct overriding capability. The variable-stability nozzles are driven by electric servo-motors and are positioned by the sum of six inputs. During the Ames investigations, the reaction jet force is determined from the sum of four different signals, consisting of three rate-gyro outputs and the pilot's control displacement. The output of the gyro that measures angular rate about the axis being investigated produces a signal which is coupled to the nozzle corresponding to that axis, while the other two gyros cause a cross-coupling motion which is used to eliminate the gyroscopic cross-coupling due to the jet engines. Each input signal is controlled by a potentiometer which enables the pilot to select the magnitude and sign of these signals. Angular rate signals are used to position the variable-stability nozzles to oppose aircraft motion in direct proportion to the angular velocity, thus creating rate-damping. The response from the pilot's input either supplements or opposes the basic reaction nozzles, and thus changes the amount of control power. Requirements of control power and damping for visual flight conditions are investigated while the aircraft is hovering out of ground effect and in generally calm wind conditions. Evaluation consists of manoeuvring at speeds up to 30kt forward and rearward, 20kt sideways, and at altitudes up to 50ft. Hovering turns, sideways flight, and forward and rearward "quick stops" have been per- BELL X-I4A Powered by two 2,450lb-thrust General Electric J85 engines with individual cascade deflection from 0C to 90:; originally the engines were Bristol Siddeley Vipers. Span, 34ft; length, 25ft; height, 8ft. The aircraft made its first free hovering flight at the Wheatfield, NY, plant of what was then Bell Aircraft Corp on February 19, 1957; complete transition from VTOL to forward flight and back again was accomplished at Niagara Falls municipal airport on May 24, 1958, and the aircraft was delivered to Ames Research Center in October 1959. Ryan VZ-3RY Vertiplane Powered by a 785 s.h.p. Lycoming YT53 free-turbine engine in the fuselage, geared to both propellers. Span, 23ft 5in; length, 27ft 8in; height, 10ft Sin; gross weight is about 2,6001b. Taxying trials began in February 1958 and free flight followed tethered trials early in 1959. On the 22nd flight, in NA5A hands, the aircraft crashed (the pilot escaped in his Martin-Baker seat); it was subsequently rebuilt. be used operationally on the C-130 or other aircraft. Modifications now are under way on the BLC-130 to improve controllability and angle of approach, and eventually flight tests of the modified air craft will be made. Ames researchers are hoping to achieve a land ing speed of 50kt, with a landing roll of no more than 500ft. Once the new capability has been demonstrated, NASA hopes wing lift can be enhanced so as to improve the C-130's thrust, weight ratio. More sophisticated controls will be required, including the use of variable propeller pitch for lateral control, and the *^K _ 1 The grotesque-looking Ryan VZ-3RY in a 70 flight profile, with full flap at 25kt. Right, the tufted Ryan on view at Ames with full flap, gas control nozzle can be seen at the end of the fuselage The exhaust formed to determine the effect of various combinations of control power and damping on the ability of the pilot to position the air craft accurately and quickly over a ground reference point. Another aircraft that has undergone rigorous testing at Ames is the Ryan VZ-3RY deflected-slipstream configuration, which has been studied for its stability and control features at low speed. Its work has largely been connected with a major effort undertaken at Ames to evolve designs for much larger V/STOL aircraft. Both propellers are coupled to the output of a single free-turbine engine in the fuselage. The jetpipe is extended to the extreme tail, and terminates in a valve box coupled directly to the pilot's controls. Shutters discharge all the gas at approximately 90° to the centreline axis in order to eliminate forward thrust; pitch and yaw moments are imparted merely by partially shielding one side of the nozzle box. Roll control is achieved by so connecting the propeller-pitch linkage into the aileron circuit that, when the huge flaps are lowered, sideways movement of the control column varies propeller pitch differentially. NASA has made flights with the Lockheed C-130 turboprop transport equipped with boundary-layer control. Field-length of this machine is roughly half that of an ordinary C-l 30, but handling qualities, such as controllability in very steep approaches, will require considerable improvement if boundary-layer control is to development of a wing with greater flap area and some tilting for slipstream coverage of the entire span. This effort, which will make use of what can be learned from the Ryan VZ-3RY, is aimed at the development of a good V/STOL transport in three to five years. Such a transport ultimately is expected to be more efficient and satisfactory than the XC-142 V/STOL evaluation aircraft now being built. This machine was described in Flight International last December 21, but much new information has now been given by Mr A. L. Robinette, manager, plans and programmes, V/STOL, of Chance Vought. Approximately two years ago—he writes—the Department of Defense decided that the next step in military VTOL effort should be a tri-Service programme to build a full-size aircraft, with a substantial payload capability, with which to conduct operational- suitability testing. A general set of specifications was developed jointly, and the Navy was designated as the DOD developing agency. In February 1961, industry was invited to submit proposals for the design, fabrication, and test of five aircraft to meet the following specifications: cruise speed, 250-300kt; Vmax, 300-400kt; combat radius, 200-300 n.m.; ferry range, 2,200-2,600 n.m.; pay- load, 8,0001b (32 troops); cargo compartment, 30ft > 7ft 6in x 7ft; carrier suitability, 50ft x 30ft x 17ft, and gross weight of 35,0001b. Continued overleaf
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