FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1949
1949 - 0168.PDF
112 FLIGHT JANUARY 27TH, 1949 Refuelling in Flight Needham gave particulars of four versions,in order to allow for future developments. They were: — F.R.13 (with piston engines driving air-screws); F.R.14 (with gas turbines driving airscrews); F.R.15 (with plain jet propul-sion); and F.R.16 (with compound engines driving airscrews). The four designs areshown in Figs. 3, 4, 5 and b. As the normal payload was the same forall four designs, the fuselage accommodation was basically the same. By arranging wingloadings, operating heights, and desired cruising speeds to give optimum conditions,it was found possible to utilize the same basic wing for all four designs. The maindifferences were to be found in the power- plant installations, and in their fuel systems.The jet-propelled project had a shortened undercarriage and a modified fin and rudder.The salient features of the four machines are given in the table.Operational data for the four types are shown diagrammatically in Figs. 7 and 8.Normal full payload of 13,300 lb can be carried in all four types for all wind con-ditions. Under average conditions the inter- ception points on westbound flights wouldbe over Shannon and Gander, while for strong headwinds the first interceptionwould be a short distance west of Shannon. Mr. Latimer-Needham dealt in great detailwith calculations and estimates for the operations, but unfortunately we have notthe space to give these considerations in detail. Overland Routes Mr. Latimer-Needham then turned to anexamination of an overland service with a flight-refuelled Handley Page Hermes. Hepointed out that it is generally permissible to bring the flying weight of an aircraft(after refuelling) to a figure greater than its normal maximum take-off weight. Theeffect of this is a further increase in pay- load, and at the same time the distanceto the optimum point is reduced, thus diminishing the tanker flight length. Referring to Fig. 9, which relates to theHermes operating over a route of 2,000 miles, it is seen that for the normal gross weightof 80,000 lb the optimum point (OP.) is 665 miles from the origin, and the payloadis 11,000 lb, an increase of 5,700 Ib over that carried in unrefuelled flight. By in-creasing the flying weight by 2! per cent of the gross weight, the payload increasesto 12,300 lb, and the optimum point distance is reduced to 585 miles. Similarly, for a 5per cent overload the corresponding payload and refuelling point distance become13.650 lb (maximum payload capacity) and 500 miles respectively. A series of formula; was given by meansof which a fairly accurate route analysis could be made. These should enable poten-tial operators to estimate the merits of flight refuel-ling on their routes. Having outlined thebenefits to be derived from flight refuelling, thenext step was to ex- amine the other side ofthe ledger and find out the cost of the operation.Mr. Latimer - Needham pointed out that it waspossible to assess the. value of some of the ad-vantages in terms of cash, but not all. Amongthe latter were the value of non-stop services, and the regularity and punc-tuality of services. To give some idea of the actual cost of fueltransfer en route, the case was taken as anillustration of a future frequency of at least two per day, in which casethe cost of a refuelling with a tanker of about FIG. 3 FIG 5 FIG Four versions of a design study of a flight-refuelled airliner to carry SO passengers. They are • Fig. 3, the F.R.I3 ; Fig. 4, the F.R.I4 ; Fig, 5, the F.R.I5 ; and Fig. 6, the F.R.I6. 65,000 lb weight should not exceed £250.This figure allowed for a tanker flight dura- tion of 2^ hours, or a radius of operationof about "100 miles. Increments of radius increased the cost by about ^30 per 100 MAIN PARTICULARS OF THE F.R.13, 14, 15 AND 16. upMax. allweight. Weight empty... Equipped wt. -!• crew. Max. fuel wt. Normal payload Wing span Length Height to top of fin. Wing area Max. wine load- Engines ... T.O. power total Max. speed at height. Cons't speed cruising. Range at coni't 5 peed (no al- lowance*). F.R.13 95,1901b 56,2601b 58,0901b 22,0001b I3.3OOIb 126ft 4in 105ft 34ft 6in 1,566 so ft 60.7lb/»q ft 4 Bristol Cen- taurus 663. 11,240 h.p. 360 m.p.h. at 20,000ft (W.M.) 315 m.p.h. at 20,000ft. 3 180 st.m. F.R.I4 101,4501b 55,6001b 57,4301b 30,0001b 13,3001b 126ft 4in 105ft 34ft 6in 1.566 sq ft 64.7lb/sq h . 4 gas turbines 13,520 e.b.h.p. 430 m.p.h. at 25,000 ft (5 min) 390 m.p.h. at 25,000ft (Max cont). 365 m.p.h. at 25,000 ft. 3,340 sr.m. F.R.I5 F.R.I6 109,5001b 48,4301b 50,2601b 45,8951b I3,3O0lb 126ft 4in 105ft 32ft 2in 1,566 sq ft 701b/jq ft 4 jet engines 26,O00lb thruu 560 m.p.h. at 30,000ft <ap- prox). 460 m.p.h. at 30,000ft. 2,900 st.m. miles. In the case of only one operation aday, if it were considered necessary to main- tain two aircraft at the tanker station, thecost would go up to ^400, or even /450 in certain localities. Basing his estimates oncertain figures given in Mr. Masefield's paper^Mr. Latimer - Needham - arrived at the conclusionthat a flight refuelling cost of /250 was equal tothe sum saved by the'. avoidance of a landingfor an aircraft weighing 135.000 lb. All otherbenefits of flight re- fuellinf! were gratis. In his very thorough -survey of flight refuel- -Id- ling. Mr. Latimer-Need- I-":..ham did not confine him-- - self to civil aviation. ';'The •» possibilities for "j bombing are obvious, v;anS he took as an ill us- i tration a hypotheticalbomber with a maximum take-off weight of135,000 lb and a maxi- mum flying weight of140,000 lb, the latter realized after refuelling.Calculations shown in graph form indicated 1 94,0001 b 58,1IO!b 59,9801b 19,2801b 13,3O0lb 126ft 4in 105ft 34ft 1.566 sq ft 60,000lb/sq ft 4 compound en- ginet. T2.480 e.b.h.p. 418 m.p.h. at 25,000ft. 316 m.p.h. 25,OO0ft. 3,450 st.m.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
