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Aviation History
1947
1947 - 1974.PDF
544 FLIGHT NOVEMBER 13TH, 1947 American Newsletter Progress of Jet Bombers and Fighters : The New Beechcraft Twin-Quad : Rocket-Propulsion ^Research By " KIBITZER " DETAILS and photographs of some new American air-craft, both civil and military, have appeared in thePress over here during the last week or two. Con- sidering how reserved other nations are about new develop- ments, the rather free-and-easy attitude of the Americans is often surprising, particularly in view of the incredible "war-talk" that goes on here in the less responsible sec- tions of the Press and community. But the publicity de- partments of the manufacturers, and even the Public Re- lations sections of the Army and ISfavy, have their job to do, and must often be torn between security and publicity, a fact that seems, occasionally, to prove somewhat em- . barrassing to those who are responsible for the country's secrets! Two cases in point are the releases, photographic and printed, of the Boeing XB-47 swept-back wing jet bomber, and photographs of the North American swept-back wing XP-86 fighter. The former, which has been mentioned before in this letter, is undoubtedly the most advanced machine of its type in the world. It is powered with six General Electric J.35 jet engines giving a total thrust of 24,000 lb. Four of the six power units are situated close to the fuselage but below and forward of the wing, being carried by forward-staggered and totally enclosed streamlined engine bearers—presum- ably so that they may be well away from the high-lift wing and help towards a better position of the e.g., which is always a difficulty on machines with swept-back wings. The other two units are farther out towards the wing tips,"where their position will undoubtedly help to lessen the bend- ing moments of the wing itself. Range of the XB-47 *s given as 2,000 miles (which must mean that the fuselage'is almost entirely filled with fuel, the wing being too thin to be of much use as a tank), while the top speed is given as 630 m.p.h. at 30,000ft ! The wing sweep-back is 45 deg. If the estimated speed is reached it will need all known aero- dynamic aids for overcoming compressibility, as the designers say the machine will be capable of Mach numbers of the order of 0.95. Despite the large size of this aircraft— it has a span of 116ft and a fuselage length of 108ft—it carries only a crew of three in the pressurized forward part of the fuselage. The armament consists of remote-con- trolled fifty-calibre guns in the tail, and a bomb bay capable of taking a 20,000-lb bomb. In order to get over take-off troubles at full load—a not inconsiderable problem—pro- vision is made for 18 JATO units, giving 1,000 lb thrust each. The undercarriage is of the "bicycle" type de- veloped by Glenn Martin, and although this machine has not flown at the time of writing, it is now undergoing taxy- ing trials and should get into the air before too long. The other swept-back wing aircraft, and one that has already flown, is the North American XP-86, about which little has been said in print but of which a photograph has been published. It is known, however, that the Army are pinning great hopes on this aircraft as a possible future world's speed-record holder (for they are still striving to regain this title from the Navy—even, it is said, to the extent of grooming the Bell XS-i rocket aircraft for the job). As this latter was designed for air-launching, this rumour should be treated with considerable reserve. The photograph of the XP-86, however, shows a modern- looking fighter of some 15,000 lb, with its wings, rather small tailplane and rudder all swept back in the neigh- bourhood of perhaps 35 deg to 45 deg. It has a central nose entry duct, but an interesting point about the entry and tailpipe orifices is that both are slightly lipped-^ at the top, giving a slight "pen-nib" shape. So far sus the en try. is concerned, one does not know whether this '' Parker Pen'' look is due to a desire to avoid certain in- take compressibility troubles, or to improve intake flow at high angles of incidence, but it is said that the lipped tail-pipe exit improves take-off thrust and helps to elimin- ate snaking at high speeds^. The civil aircraft of which a photo has been released ,is the long-exrj^ed/ Beechcraft rer machine. (see Flight, October i6£ Model 34, a twin-screw The XB-47 makes its debut. Features apparent here are the underslung jet units, "bicycle" undercarriage and built-in A.T.O. installation. Fitted with four 375 h.p. Lycoming engines, coupled to- gether in pairs driving a single airscrew on each wing, ranges of up to 1,400 miles at a cruising speed of 180 m.p.h. are claimed at very economical operational figures. It has the Bonanza-type butterfly tail, and wings with a certain amount of taper, but the cabin looks rather square andL ugly, although its shape is undoubtedly efficient for bothjl passenger and cargo space. The engines are almost com- pletely buried in the wings and have leading-edge intakes, but the airscrews themselves are situated well forward of the 'wings, being presumably shaft-driven from a gear- box so designed that an inoperative engine can be dis- engaged by the pilot. So far Beechcraft have been very quiet about the whole project, but have stated that they do not intend to build any until an adequate number of orders are in hand. Which opens up the old question, which should come first, the aircraft or the orders? TESTS WITH THE XS-1S OME further details of the Bell XS-i research aircraft have also been released, and although this machine was only designed in the first place as an intermediate step towards a rea) supersonic type—possibly the XS-2— the data on its construction and performance are interest- ing. Of quite conventional plan form, but designed for air
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