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Aviation History
1948
1948 - 1584.PDF
380 September -23rd, 1948 CARRIER-BORNE ROMRER Composite Powered XAJ-1 : P. and W. Double-Wasps and a G.E. Turbojet THE latest in U.S. fission fashions is announced byNorth American Aviation, Inc., acting in concertwith the U.S. Navy. (The fission part may be purefiction, of course, but guessing is still uncensored, as well as a good sport, on both sides of the Atlantic.) While the flight debut of this aircraft has been publicly known and seen—and even reported in the American press—for the past couple of months, the U.S. Navy has only just re- moved its iron glove from the velvet curtain. Fortunately, the curtain has not yet been made that reaches higher than the airport fence. Apart from any guesswork about the naval functions of this aircraft, the main technical interest centres around the composite power plant, featuring a pair of Pratt and Whitney Double-Wasp piston engines on the wing and a General Electric (Allison) turbojet in the rear of the fuselage. This mixed power plant theme is apparently still a favourite with the U.S. Navy and has been seen before in the Ryan Fireball fighter and the Martin Mercator bomber. The piston engines with their Hamilton four- bladed airscrews provide high thrust for carrier take-offs and also good high-speed performance at altitude, and are used, therefore, for normal operations. The turbojet re- mains up the fuselage sleeve, so to speak, to be cut in for speed-boosting under combat conditions. In size, the XAJ-i is similar to North America's B-45 four-jet short-range bomber for the U.S. Air Force, which means that it is bigger and heavier than present carrier- based types. Nevertheless, it is lighter than the Navy's Lockheed Neptune, which has recently completed a number of successful carrier take-offs. A crew of three is carried in a pressurized cockpit. Other features not observable in the accompanying photograph are a tricycle nose-wheel landing gear and folding wings and tail for ease of handling and deck maintenance. The outer panels of the wing fold up and inward, while the vertical tail folds against the star- board surface of the horizontal tail. One noticeable feature is the very neat streamlining of the undersluns; piston engines on the wing, for not only is the nacelle itself exceptionally clean-cut and free of un- sightly blisters, but the cowl lines are well faired into the laminar-flow wing profile. Flush-type exhaust exits are located on the sides of the cowl underneath the wing— where they appear well-placed to scorch the lower wing skin. Whether this particular installation is intended as a thrust augmentor is not known, but in that case one might have expected to see the exhaust carried through clear to the tail of the nacelle, similar to the arrangement seen in the Republic XR-12 Photo-Scout and, more recently, in the Convair-Liner transport. Such a scheme has the dual merit of carrying the exhaust clear of the wing and provid- ing a modicum of jet propulsion. Obscured in the official picture is the air intake to the central turbojet, which is aspirated by fuselage side nostril ducts located under the wing. Also discreetly hid- den are the long, ingeniously designed bomb-bay doors, which give the impression that the XAJ-i is designed to play the rdle of a carrier-based atomic bomber. This seems a logical deduction, since the U.S. Navy is now laying down the World's super carrier expressly designed for atomic bomb delivery—presumably in an effort to trump the Air Force. This carrier will have a flush-deck, a waterline length of over 1,000 feet, and an estimated gross tonnage of around 80,000 U.S.'tons. Top-ranking Air Force'opinion has publicly berated this ambitious project as " a highly vulnerable ocean platform for launching a few bombers against enemy industrial centres." Apropos the XAJ-i, there is some doubt as to whether this particular brand of fruit compote is quite the dish the U.S. Navy appears to think it is. In view of current pro- gress with turboprop engines, by the time this big American carrier is launched in 1952, the high-powered piston engine may be outmoded. Despite recent progress in America with the compound piston engine (both Pratt and Whitney and Wright are developing this type), it seems much more logical—if one must serve a mixed dessert—to concentrate entirely on the turbine engine. On paper, at any rate, the most promising combination of all was undoubtedly the turbojet with ducted fan; hence it would be inter- esting to know the current status of this type of composite turbine. While, therefore, the XAJ-i is an interesting example of current American naval air thinking, in the opinion of this writer (a mere layman), it seems a fantastically expensive way of delivering an atom bomb on the target. The aerial part of the bill is practically unnoticeable, compared with the cost of the giant carrier and its huge flotilla of protec- tive escorts, representing in all a total investment roughly estimated to run as high as 1,000 million dollars. All this expensive convoy offers a sitting target close in-shore for the latest type of submarine, against which no satisfactory protection has yet been devised. Clearly the American tax- payer is about to learn the high price of admiralty in this post-atomic age. "FAVONIUS."
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