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Aviation History
1956
1956 - 0709.PDF
709 Nerd 1500 Griffon. The F-lOlAs are intended for Strategic Air Command and the firsttrue production machine should be coming through in June. By April this year 31 development Voodoos were reported to have beencompleted. Span, 39.7ft; length, 67.4ft; gross weight, over 40fi00 1b.McDonnell F-101B Voodoo An intercepter version of the F-101A, armed with Hughes Falcon missiles, this variant is likewise in production.Destined for Air Defense Command, it is intended to "operate under all weather conditions to execute two primary missions—the identifica-tion of unknown aircraft and their destruction if they are hostile." North American F-86D Sabre. Although it appears likely that theHughes Falcon air-to-air guided missile will progressively be adopted as the primary armament of this single-seat all-weather intercepter itspresent standard armament is a battery of 24 Mighty Mouse folding- fin air-to-air rockets, carried in a retractable tray in the belly of thefuselage. The Mighty Mouse has a calibre of 2fin and a striking power roughly equivalent to that of a 3.7m shell. It is spin-stabilized, thefour narrow-chord fins being folded while it is contained in its launch- ing tube. Acceleration at launching is extremely high and 2,000 m.pJi.is rapidly attained. The warhead is normally set to explode at a range of about 1,000ft or upon impact. The rocket battery is fired in conjunction with a Hughes E-4 fire-control system which, when it picks up a target, "locks on" and, by means of a Lear automatic pilot, steers the aircraft so as to effect aninterception. The flight path is so controlled as to aim the fighter at the target when the latter crosses the fighter's bows. Known ascollision course, or lead collision interception, this method of attack is an established procedure in U.S.A.F. squadrons. Based on the Mighty Mouse rocket salvo, the Hughes fire-controlsystem works in the following way. The pilot is vectored towards his target by G.C.I. in much the same way as for a stern chasing attack,but he is not placed astern of his quarry. The attack can be made theoretically from any quarter at the same height, but aircraft character-istics make a head-on approach rather dangerous and it is the object to avoid stern-chasing. The ideal is 90 deg abeam. The pilot has infront of him, in the centre of his normal blind-flying panel, a radar scope. His aerial is scanning a vertical fan beam backwards and for-wards laterally, and the trace of this appears as a fast-moving vertical line on the scope. Superimposed on this presentation is a line resemblingin aspect and function the horizon bar of the normal artificial horizon, so that the pilot can fly blind watching the scope alone and occasionallyreferring to the A.S.I or other instruments. At a certain point the target echo will appear as a blip on the screen.Its range and bearing will be indicated by its position on the scope, vertically for range and sideways for bearing relative to the intercepteVscentreline. The pilot then locks his aerial to follow the blip only by manoeuvring the aerial's search trace—by manipulating a handle untilthe line is stationary across the blip. He then presses a switch on the grip which causes die blip to glow larger. The set is then locked on. Immediately a ring appears together with a steering dot. The ringwill be large in diameter and a break in its circumference will appear opposite the relevant point on a scale round the edge of the scope toindicate the rate, in feet per second, at which the intercepter is closing on the target. The steering dot will be so positioned on the scope thatif the pilot manoeuvres the aircraft to bring the dot into the centre of the ring, referring the while to the artificial horizon bar, his course will becorrect for eventual firing of his rockets. The distance between intercepter and target closes, and when thefiring point is 20 sec away, the diameter of the large ring will decrease until it closely surrounds the steering dot. At that point the pilot mustfly very accurately as the critical moment of firing is at hand. A little over four seconds short of firing, a signal on the scope tells the pilot topress the firing trigger to arm (but not fire) the rockets. He has already selected the number of rockets he wants to use. At the exact momentthe rockets are fired, and a large X appears on the scope to tell the pilot he is free to break away. Should he fail to get into proper position,the X will denote a missed pass and the rockets will not be fired. The rockets travel much faster than the aircraft towards the target,so that the intercepter can fly straight on at the same height after firing without colliding with the target. In a head-on attack, of course, actualevasive action would be required and this consists of pulling 50ft upwards under automatic control. However, the exceedingly shorttime available for the controls to take effect and produce this manoeuvre, not to mention the lag which may occur in the aircraft, due to high indicated speed, of sloppiness at very high altitude, leave little hopeof successful evasion in any but the most favourable conditions. After the attack the radar can be set up for further interception, ifany rockets remain; or it can be deflected downwards and used for map-painting and general navigation. A base so distinctively placedrelative to a prominent coastal feature as Mansion, where F-86Ds are operating, would give echoes probably good enough to allow a reason-ably accurate approach to the glide-path in poor weather or at night with the aid of the aircraft's radar alone.It was learned at the Fighter Weapons and Rocketry Meeting of the U.S.A.F. Air Defense Command during 1955 that maintenance ofthe Hughes fire-control system showed improvement over the previous year but, according to Aviation Week, "still had a long way to go" inreaching "acceptable reliability." The commander of the training base estimated that the great majority of misses were due not to errors on Nord 1405 Gerfaut II Marcel Dassault Super Mystere B.I. SJ1.C.A&EJ12 Durandal.
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