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Aviation History
1953
1953 - 1223.PDF
FLIGHT, n September 1953 379 HEMISPHERICAL BOMBING . . . Three years ago, Flight Refuel ling fitted three hose units to this KB-29 and trials were con ducted with R.A.F. Meteors (Mks. 4 and 8 shown) and U.S.A.F. fighters of various types. The wing-tip units were care fully designed to keep the drogue and the fighter clear of vortices at all times during fuel transfer. J* •;.. •. • EMM -' * -o—*•- a refuelling radius of about 1,020 miles, where some 46,000 lb (5,700 gal) of fuel can be transferred. This has the effect of increasing the ultimate radius from 2,750 miles to 3,950 miles. If this maximum quantity of fuel is to be transferred at the refuelling point thus obtained, it will be seen by Fig. 8 that, for the bomber to be able to return to its base in the event of a baulked refuelling, the maximum bomb-load cannot exceed 46,000 lb; and in order to accommodate greater bomb-loads the refuelling must take place at a shorter radius, where the bomber is unable to accept the full quantity of fuel available in the tanker. This gives a kink in the bomb-load diagram. (Fig. 9.) As the distance to the refuelling point becomes shorter there is a radius at which one tanker is able to refuel two bombers, and the diagram shows this to be 260 miles from base; it will be noticed that under this arrangement the maximum bomb-load per bomber (assuming capacity to be available) is about 66,000 lb, at a radius of 1,320 miles. In practice a small additional fuel allowance might be found necessary if the two bombers were to be refuelled consecutively. Bomb-loads have been plotted in Fig. 9. The diagram shows that whereas, unrefuelled, the radius for a 10,000 lb bomb-load is 2,370 miles, the bomb-load, flight-refuelled, at the same radius can be increased to 47,000 lb. It is also seen that the bomb-load carried by each of two bombers when refuelled from one tanker is not much less than for the single bomber/tanker ratio. This is par ticularly so at radii below 2,440 miles, where the fuel transfer restriction comes into play. The bomb-loads have been repeated on Fig. 10, expressed as average bomb-load per aircraft, taking into account both bombers and tankers. From this it will be seen that flight-refuelling increases the average bomb-load at radii above 1,610 miles for the single bomber /tanker ratio, and above 1,230 miles for the multiple refuelling condition. It is also seen that for maximum bomb-load per aircraft the two-bomber-to-one-tanker ratio should be used up to a radius of approximately 2,400 miles, but that at greater radii the best results are obtained by the arrangement of one bomber to each tanker. For the aircraft considered, Fig. 8 shows that the optimum return refuelling point is 1,820 miles from base, with a fuel transfer of 24,500 lb (3,050 gal). Used in conjunction with the single outward refuelling, the ultimate radius is increased to 5,160 miles, or for the two-to-one outward refuelling the ultimate radius becomes 4,780 miles. The bomb-loads for various radii hi. v; been ed Jed to Fig. 9. Tanker Requirements.—In the example being considered it is possible for a single tanker to carry out both the outward and the return refuellings for all the bomb-load cases given, instead of separate tankers being employed. For example, for the single outward and single return refuelling case, for the 40,000 lb bomb-load, the distance to target is 3,640 miles, or an out-and-return distance of 7,280 miles. The tanker's flight distance, returning from the first refuelling and flying out to the second refuelling is 1,020+ 1,820=2,840 miles. Hence, the time for turn round of the tanker is equivalent to 7,280—2 x 2,840 •= 1,600 miles flown by the bomber. For a cruising speed of 600 knots, this amounts to 2.93 hours. Again, for a 50,000 lb bomb-load, distance to target and back is 6,320 miles. The tanker's flight distance from the first refuelling to the second refuelling is 860+1,820 = 2,680 miles. Hence, the time for turn round is equivalent to 6,320 — 5,360 = 960 miles, or, 1.60 hours. Lastly, for a 60,000 lb bomb-load, the distance to target and return is 5,060 miles. The tanker's flight distance between the two refuellings is 480 +1,820 = 2,300 miles. Hence, time for turn round is 5,060 - 4,600 = 460 miles, or, say, 0.77 hours. (A border-line case.) For the two-to-one outward and one-to-one return refuelling and a maximum bomb-load, viz. 60,000 lb, the distance to target and return is 4,820 miles. The tanker's flight distance between the first and second refuelling is 260 + 1,820 = 2,080 miles. Hence, time available for turn round of the tanker is equivalent to 4,820 - 4,160 = 660 miles, or, 1.1 hours. This means that in all bomb-load cases the same tanker can do both refuellings, and, therefore, the bomb-load of two bombers is shared between three aircraft. MAXIMUM DISPOSABLE LOAD \x CAPACITY BOMB LOAD _ REFUELLED OUT AND IN IBM! REFUELLED OUT 2B.1T. REFUEL IN 1B:1T 1pbO 2000 3DOO 4.000 BOMBING RADIUS (n. a.m.) 5.000 Fig. 9. (Left) bomb load diagram—150,000 lb bomber. Fig. 10. (Below) Average bomb load per aircraft—150,000 lb bomber. * 60h 1000 2000 3000 4000 BOMBING RADIUS (nam.)
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