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Aviation History
1990
1990 - 2914.PDF
A FA CONVENTION USAF A-12: now you see it... Contractors exhibiting a small model of the USAir Forces's proposed version of the US Navy's classified A-12 attack aircraft say that they were told by the Navy to remove it, and then — by the Air Force — to put it back. General Dynamics (GD) says that the Navy told it to remove the A-12 model from its stand at the Air Force Association's (AFA's) annual convention in Washington, but Air Force sec retary Donald Rice's office countermanded the instruction a day later. It showed the aircraft's plan- form as being almost a right- angled triangle with a virtually straight trailing edge and no vertical tail surfaces. The twin F412 engines had the trapezoidal inlets previously shown in the Navy's artist's impression but the nozzles were also visible side by side in the rear "fuselage", exhausting over the upper-fuselage flat area and reminiscent of the YF-23's noz zle design. Two adjacent flaperons were visible on each wing trailing edge, together with a single third surface hinged from the central trailing edge and a type of leading-edge lift device — possibly conventional slats. A refuelling point appeared on the top surface well behind the prominent tandem cockpit but no tailhook was visible. General Dynamics says that the naval aircraft has folding wings for carrier operation. GD staff say that the Navy did not object to the model being shown in public but did object to it being at the AFA conven tion. The Navy was unable to comment at short notice. A Navy briefing to the Tail- hook Association earlier this month showed the A-12's un folded wingspan as being slightly wider than the 19.45m of an F-14 with wings forward, its length at about 10.8 m and its folded span at around 9.85m. Navy officials said its short length gave it a smaller carrier footprint when folded than the A-6 it is to replace. • Boeing studies two- crew KC-135 upgrade BY KIERAN DALY Boeing is offering an upgrade for the US Air Force's 640- strong KC-135 tanker fleet that would allow a two-man cockpit crew to operate the aircraft. Boeing, which made the sug gestion in response to a USAF Request for Information, says that the aircraft could be equipped with a glass cockpit for less than $1 million each. Director of KC-135 program mes at Boeing, Steve Starch, says that if the need for navigators was eliminated then up to 1,000 fewer personnel would be needed for the tankers. Starch says that further sav ings in the maintenance costs of new-generation avionics against the existing fit would result in the programme paying for itself in three to five years. He explains: "The Air Force's Lockheed liquid-cools ffTF avionics vironment compared with any thing out there today and it is in our proposal." Mullin says that the avionics now account for about 25% of the aircraft's flyaway cost but only about 6% of the weight —both figures markedly lower than earlier estimates. The three main contractors have now finished their finan cial investment in the pro gramme, which totals $675 mil lion, together with $410 million from subcontractors, $817 mil lion from the Government, and engine contractor money. Mullin says: "The Air Force has made it clear that it is looking for a balanced ap proach. Anybody who goes hog- wild on stealth or on avionics or on supersonic aerodynamics will be in trouble. The last four years we have spent doing more trade-off studies than I have ever done before in getting what is the right balance in the aircraft." He says that Lockheed is also looking at incorporating some YF-22 modules in possible air craft for the US Navy's Ad vanced Tactical support (ATS) aircraft requirement or E-2C update. "We have looked at the op tions for ATS with the Navy. One is a new aircraft and one is an S-3 derivative. In both cases we have looked very seriously at using a large amount of ATF avionics," says Mullin. D Avionics in the Lockheed/ Boeing/General Dynamics YF-22 contender for the USAF Advanced Tactical fighter (ATF) contest will operate at tempera tures as little as half those expreienced in current fighters, according to programme man ager Sherm Mullin. The consortium says that reli ability of the liquid-cooled avi onics in the aircraft, which is due to fly in the next few days, will be about four times that of the F-15, and Mullin explains that lower operating tempera tures are a key factor. The YF-22 system allows liq uid to circulate through the shelves between the avionics racks which contain about 100 electronic modules. Mullin says: "We are trying to keep to a 60°C temperature at the junctions, which are the hottest points on the racks — current avionics typicallv run at 100-C to 120'C. "Using liquid cooling in the common integrated processors, radar and most other units was a fundamental change in our analysis. We had been agonising over how you get better avionics reliability and we decided to do the obvious. A lot of the prob lems are thermally induced be cause [avionics] get too hot and their temperature fluctuates constantly, which no doubt causes failures. "The system we are using is a totally different operating en- . «iSiBpa^(| I Warn first concern is that the reliabil ity and supportability of their present instruments are deterio rating as the years go by". Boeing figures show mean times between failures of about 200h for the KC-135 radar com pared with about 6,000h for a 737; 400h for the inertial navi gation system compared with ll.OOOh; and about 300h for the horizontal situation indicator compared with 17,000h. Starch says that the KC-135 structures have a fleet average used life of only 10,000h out of a 30,000h expected life, which would allow them to operate beyond 2020. All of the fleet is being reworked to KC-135R standard by re-engining with IR software aids US Gulf targeting US Air Force aircrew using precision-guided munitions in the Gulf will be able to use new computer programmes to predict maximum stand-off ranges and target infra-red sig nature appearance. USAF Systems Command (AFSCOM) says that software packages called tactical decision aids (TDAs) allow weather fore casters and crews to employ infra-red, television, laser or millimetre-wave guided weap ons more effectively in extreme conditions. Maj Jim Hancock of AFSCOM says: "The drawback of preci sion guided weapons is that weather can limit their use and the effect of conditions is not always intuitive. "For example aircrew search ing with infra-red for a target in 6 FLIGHT INTERNATIONAL 26 Seplember - 2 October, 1990
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