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Aviation History
1980
1980 - 1643.PDF
FLIGHT International, S July (980 35 Wm mm TOM %M HiMAT technical description GRAHAM WARWICK reports from Los Angeles FLIGHT-TEST results form the basis of aircraft design. Empirical de sign relies on rules of thumb derived from experience. HiMAT is a highly manoeuvrable research vehicle built to calibrate the thumbs of those engineers designing the next wave of US fighters. Built by Rockwell International, funded by Nasa and the US Air Force, HiMAT is a remotely piloted vehicle incorporating innovations aimed at increasing the manoeuvr ability of future combat aircraft. As many advances as economically feasible are squeezed into an airframe little more than 20ft long. The aim— to outmanoeuvre the F-16 in the crucial transonic regime where most air combat takes place. Maximum sustained turn perform ance is reached when available thrust is matched by drag generated in the turn. The dominant component is drag due to lift—induced drag. Shock- induced separation of airflow over a wing causes drag to rise before Mach 1 is reached. To improve tran sonic turn performance it is necessary to delay separation and to operate at the lowest possible angle of attack. Few technology advances offer a significant performance increase in isolation. Test programmes centred on a single innovation often avoid the problems of integrating that advance into an operational aircraft. Incorporating many innovations in a full-size airframe can be costly and risky. HiMAT is designed to investi gate high-risk technologies, and their interactions, at minimum cost and risk. HiMAT is a scale model required to demonstrate the manoeuvring per formance of a full-size 1990s fighter capable of a sustained 8g turn at Mach 0-9, 30,000ft. In similar condi tions, the F-16 will pull 4J2g and the F-4E 334g. Constrained by the need to Cutaway by IRA EPTON use an existing engine, Rockwell en deavoured to match thrust-to-weight ratio and wing loading at the tran sonic design point. The match was made with a 44 per cent scale model powered by a 5,0001b-thrust General Electric J85-21 afterburning turbojet. So a 17,0001b fighter became a 3,4001b model aircraft. Rockwell identified 32 technology features suitable for the 1990s fighter design and, after trade-off studies, selected those which offered the biggest payoff at acceptable risk. Economics and time dictated that some of these prime technologies could not be incorporated in the scale model. Others could not be used to their full extent, but the eventual research vehicle is a close approxi mation to the fighter. Features selected for the fighter were: close coupled canard; blended wing/body; vortex strakes; Rockwell aerofoil; variable-camber wing; drag i 4 5 19 Steel landing legs and skids 31 Fuel shut-off valve 3* H?; h^o"i~p-*r<~p 33 Routing tunnel 34 Generator 35 Batteries •• • *5. '..;•:,.;•..•" • "J,;;- tl Oil toowr 38 Throttle actuator 39 General Electric J3S-2I engine: 5.0001b thrust •::'#K '1-y.^f ;ik.^:k: 41 Routing tunnel #2. f s... <• ;-,i ,< •>- n 43 Fuel-level control valve 4# F.j*l?S! *r •" " •.•;• • ."<!>< I •••' • «, - '•••/• ,•; . t: i. .;:. „< .1 , ..y 47 Lan/ard iwitch 48 Forward engine .suspension 49 Linear accelcromecer •; •••>••••• •••-, •<••..-'• 52 Engine oil cooler 53 Oil tank 54 Scarcer-air adapter 55 Elevon servo-valves 56 Pressure switch 57 Emergency reservoir ..' ; i .-:,•<•;•.. iVt\!'llii'lj 59 Fuel iei-purr.D 60 Demodulator 61 L-band uplink antenna 62 Dump valve 64 Elevator actuator 65 Elevator servo-valve 66 Elevon actuator • ! . i jii . 69 Aileron actuator •:'-% l e 71 Undercarriage up-lock .• ••.•••:..•; 73 Hydraulic actuator lock ":•:*• 75 Smoke generator \ •(: :•••..• ',,•••>.:• •' » 'V&Sl • :•./:.:: r •' • :• •••. • •••.< •••'••< • ••;; •: « •.•• r • ... n 81 Elevator (carbon-fibre): 20 up. 30 down 82 Elevon (carbon-fibre) 16 77 up, 25 16 down 83 Winglet: carbon-fibre laminates 84 Aileron (carbon-fibre): 17 66 up. 17 66 down 85 Replaceable glassfibre leading edges 86 Titanium wing-to-tail-boom structure 87 Replaceable carbon-fibre leading edge 88 Canard flaps: 14 75 up. 14 75 down 89 Canard: carbon-fibre laminates ,3 . •••!': O'i • •>.. • ; •••••.;• •••: ••:?. I :>•>•;• ,::. . ' /: ••• h'.i »:ds'i •• : i '.• -:•..••• ••••;: 94 Windshield shroud 96 Underwing panel—inboard
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