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Aviation History
1950
1950 - 0254.PDF
168 FLIGHT, 2 February 1950 AMERICAN NOTEBOOK By Stanley H. Evans F.R.Ae.S., A.F.I.Ae.S. PROBATIONARY PROBOSCIS UNLIKE the elephant, which seemingly remains self-satisfied with its antediluvian suctorial organ, thegas turbine has not yet settled down to the dull conformity of a standardized breathing apparatus. As might have been expected from radial-engine cowling prac- tice, the nose type of air intake (seen in the original Gloster- Whittle design) led the fashion parade. Current turbojet installations, however, show a wide variety of aspiration systems, being adapted to breathe through the nose, mouth, ears, belly, dorsal, or reversed piscatorial gills of the fuse- lage anatomy ; or through various forms of leading-edge scoop in the wing. Whether to ascribe this to the versatile touch of genius or the changing whims of the aero-thermo- dynamicist may be a nice point, but beneath the surface lies the more prosaic (but vitally important) sphere of the equipment designer struggling to shoe-horn all the military essentials into a very tight-fitting shoe. And of all the essential military equipment that has to be compressed into the smallest possible fringe of air- frame, the armament group rates top priority and cannot be subordinated to any other design requirement—not even optimum aerodynamic performance. The classic doctrine that a fighter aircraft is only as good as its offen- sive armament has been proved in two wars and is likely to remain a truism, since the prime reason for putting a fighter into the air is, obviously, to bring its ballistic punch into action on a target. But the modern jet fighter is now learn- ing to probe with radar, and so to the ballistic side of the business has been added the trickery of electronics for sight- ing and even gunlaying on the target. Because, therefore, armament and radar must function hand-in-glove, considerable research and design develop- ment has been directed towards improved engine aspiration systems which leave the nose extremity of the fuselage avail- able for the installation of a radar scanner and ancillary equipment. Thus, in our recent review of the Douglas Skyrocket (Flight, January 5th, 1950), we have drawn attention to the submerged, flush-type inlet scoop now com- "... the YF-86D differs from the rest of the famil/ line in breathing through the mouth instead of the nose . . . what might have been a proboscidean dead-end or cul-de-sac has been warded off." " ,^ • j ;. ing into vogue in the U.S.A., but an interesting application of what can be done as an interim or probationary measure to an existing nose-type intake, to adapt it for modem radar requirements, may be seen in ,the North American YF-86D, now under flight test at Muroc. To appreciate the design background of the YF-86D, a note on the aspiration system of the standard F-86A Sabre is relevant. It features a single, straight-through ram duct with nose entry, patterned like its naval cousin and predecessor, the FJ-i Fury shipboard fighter, on earlier N.A.C.A. research ; at the time the F-86A was on the board in 1944-45, this arrangement was considered the most effi- cient aero-thermodynamic combination. The Republic F-84 also falls in much the same category, except that the duct is bifurcated to clear the pilot and controls. Lock- heed, on the other hand, have always avoided the nasal accent, preferring to inhale through the ears, as it were. From which it should not be inferred that our Lockheed friends were more prescient than the rest (at any rate, in Tha North American YF-86D is a second edition of the well-known F-86A Sabre and has been designed as a high-altitude interceptor fighter. Noticeable changes from the first edition are the mouth-type air intake and nose radome, together with the addition of an afterburner to the Gensral Electric '-47 turbojet unit.
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