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Aviation History
1952
1952 - 1273.PDF
9 May 1952 549 MARATHON DATA (Four D.H. Gipsy Queen 70s: 34S h.p. for take-off) Span Length Height Wing area All-up weight Wing loading Max. speed at 6,750ft W.M. cruise at 5,000ft „ at 10,000ft ... at 14,500ft ... Rate of climb (max. weight), 4 c 3 Absolute ceiling Take-off run (18,0001b) ... to 50ft Landing, from 50ft ... Cabin length (civil version) ,, mean height ,, „ width ,, capacity „ 65ft 52ft 1 in 14ft 1 in 498 sq ft 18.000 lb 36.1 Ib/sqft 232 m.p.h. 200 m.p.h. 209 m.p.h. 196 m.p.h. 683ft/min 246ft/min 18,000ft 560 yd 1,030 yd 790 yd 18ft 6ft 2in 7ft 9in 760 cu ft Recently the Secretary of State for Air, Lord De L'Isle and Dudley, V.C., accompanied by Air Marshal Sir Hugh S. P. Walmsley, K.C.I.E., C.B., C.B.E., M.C., D.F.C., A.O.C.-in-C. Flying Training Command, visited Woodley Aerodrome, Reading, to inspect the Marathons. They were escorted by Sir Frederick Handley Page, C.B.E., and by A. Cdre. A. V. Harvey, C.B., M.P., who is a director of the company. Another aircraft in the running, which has already found favour with the Navy, is the Percival Prince (or Sea Prince as the variant is called) and a development of the design, under consideration by the R.A.F. for crew training as well as its other roles, has been named Pembroke. The modifications required for R.A.F. Marathons are not of a major kind; they amount mainly, as one would expect, to an interior refit. The engines, de Havilland Gipsy Queen 70/3S, are retained for the R.A.F. Marathons, and in order to give adequate range for the new duties, fuel tankage of 410 gallons is being provided. Four main-wing tanks carry 216 gallons; two new tanks in the outboard engine nacelles hold 130 gallons; and the four standard overload tanks in the wings contain 60 gallons. This is sufficient for an extreme range of 1,400 miles, or 7$ hours' duration at weak mixture cruising. This meets the requirement of five-hour training nights, and the Marathon can also cruise at 15,000ft as called for in the provisional specification, oxygen being provided in R.A.F. versions. Several combinations of crew are possible, and the accompanying plan indicates the seating arrangements, which, subject to confirmation, will be standard for R.A.F. machines. It will be seen that there are stations for a first (or staff) pilot, second pilot, radio operator, navigational instructor, ist u/t. navigator and 2nd u/t. navigator. In addition, a "gash bod" might be carried for special exercises or experience. The second pilot could be u/t. for four- engined experience or revision, or the seat could be left empty. For some training work the ist u/t. navigator might navigate the aircraft and the instructor could then be a wsrouow Mock-up of a proposed bomb aimer's station under the Marathon nose. This may possibly be adopted as a retrospective modification. w/op., and the w/op.'s station be occupied by a pupil. It is expected that the following equipment will be carried: Gee, Rebecca, radio compass, twin V.H.F., 1154-55 M.F., astro-compass, sextant, radio altimeter, G.4B compass and, when available, I.L.S. with Zero Reader. Two separate intercom systems are to be installed so that instruction can proceed without interfering with flying instructions or vice versa. Four generators are fitted. Detail differences externally visible will be blister windows beside each of the u/t. navigators' stations, and an astro-dome near the entrance door. A possible retrospective mod. is a bomb-aimer's position which would be faired into the underside of the nose on the starboard side. It would be entered through a hatch in place of, or near to, the second pilot's seat. The window nearest to the main door will be hinged to allow a camera to be used for pin-point and turning-point identification. The navigators' desks are of the large Varsity-type and their seats face backwards and are stressed for 25g. The usual R.A.F. emergency kit is carried, and the escape hatches and doors as provided for civil Marathons are retained. Pilots will notice several changes in the R.A.F.-type instrument panel (the flexible coaming is retained), and a full cross-feed fuel system is now provided. The earlier manual arrangements have been replaced by electric fuel-cocks. Deliveries with all changes incorporated are due to begin on July ist. One machine will go to Boscombe again for examination, although the aircraft as such was passed out many months ago. Another will go to a navigational training unit for appraisal. Three aircraft are to be delivered in August, three in September and three in October, and afterwards at four per month. During this period West African and Burma aircraft are also to be delivered. We may add here some brief details about the civil versions. W.A.A.C. are having increased fuel-tankage up to 350 gallons (i.e., they will have no overload tanks), while U.B.A. will have the full capacity of 410 gallons. Both types will have Gipsy Queen 70/4 engines, but, as in the R.A.F. version, reversing airscrews are considered unnecessary. A special ventilation system is installed for tropical climates, and the heaters are omitted. W.A.A.C. are making provision for a crew of two only in their first four aircraft—captain and 2nd officer/radio operator—while U.B.A. will carry a crew of three with separate radio operator in their three aircraft. The Marathon is the sort of aircraft that pilots like, and Boscombe's handling reports were good. Roominess, excellent view out and four-engined safety are all qualities which we believe will lead to popularity in the R.A.F. G.A. drawing and interior arrangement of the R.A.F. Marathon.
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