FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1962
1962 - 1171.PDF
81 •LIGHT International, : July 1962 This general-arrangement drawing may be compared with that which accompanied the original Avro 748MF submission to the Ministry of Aviation, a copy cf which was reproduced in our February I issue. Major changes are discussed in the text. The shaded areas are those which are of completely new design, and the "kneeling" arrangement of the main legs gives the two wheel positions and ground angles indicated THE 748MF TAKES SHAPE Progress with Avro's Close-support Transport PRELIMINARY details of the Avro 748MF were given in our issue dated February 1 of this year. At that time the aircraft had just been chosen by the Ministry of Aviation to meet an RAF requirement for an aeroplane capable of carrying a wide range of military equipment, including vehicles, and of operating from short, unprepared strips. Such a machine is needed to provide close-support airlift for all manner of limited-war operations; it could fulfil a variety of other military roles and should also find applications as a singularly versatile civil transport. The Standard of Preparation for such an aircraft was issued late last year, and A. V. Roe & Co Ltd tendered the 748MF design in December. The company had previously studied several military derivatives of the 748 airliner, and had also carried out a series of flight trials to prove the exceptional STOL performance of this aircraft. These trials culminated in January with operations at maximum weight on both one and two engines from deeply rutted soft mud at Martlesham Heath. It is the company's claim that the Flight Manual for the 748 airliner shows this aircraft to have a field performance superior to that of any comparable civil aeroplane yet flown. The high-lift wing profile combines with simple Fowler- type flaps to achieve a maximum lift coefficient of 3.1, with a fixed leading edge and no high-lift devices of any kind. As a result Avro were able to meet the RAF requirement with a completely straight forward and simple aeroplane, which differs from the civil airliner in the following major respects:— The engines arc the most powerful type of Rolls-Royce Dart, the R D«.12, driving 14ft 6in reversing propellers. The location of the wing on the fuselage is 3ft further aft and altered in other respects: the centre fuselage above the wing box is new; and the rear fuselage is lift longer and of entirely new design incorporating a i-.-ar-loading door system. ^ internally, the 748MF has a strengthened freight floor, loading system, provision for a navigator's station and crew toilet, and special military and operational equipment. The wing centre-section is extended 18in on each side, and 21in has b =<;n removed from each wing tip; in addition, the integral tankage is extended and the wing structure locally reinforced to permit rough-field operation at increased gross weights. The vertical tail is increased in area and the horizontal tail reduced in size and tilted to a dihedral angle of 15°. The undercarriage has larger tyres and incorporates a "kneeling" system with the aid of which the sill of the rear door may be placed at any desired height from the ground. Minor alterations have been made to the shape of the nacelles. It is appropriate to discuss each of these features in turn. Little amplification is needed on the first point, beyond noting the similarity of the RDa.12 to the civil RDa.10, deliveries of which have already been made to Japan for the YS-11 transport. Dry take-off ratings are the same (2,400 s.h.p.), but the water/methanol system of the military engine has a higher maximum flow-rate and thus permits greater power to be obtained under all conditions. To bear the increased thrust and torque loads the engine moun ting and sub-frame are strengthened. Dowty-Rotol have designed new blades for the propeller, with a profile giving maximum thrust at low forward speeds. Other features of the propeller are automatic pitch-coarsening and a conical spinner. An increase in fuselage length was necessitated by the require ment for 39ft of pay load space behind the flight deck. The interior is completely unobstructed, and has a flat floor entirely at one level. The cross section is a true circle, with an external diameter of 105in, and the pressure differential is 5.51b/sq in. Floor width is 82.12in, and the nominal loading envelope is a width of 76in to a height of 38in tapering thereafter to a width of 48in at the limiting height of 65in. These limitations may be substantially exceeded locally. In recent weeks the design team at Chadderton have spent a great deal of time on the rear fuselage and door system, which has now reached the final design stage. Comparison of the three-view drawing with that published on February 1 emphasises that the rear-end design has been g reatly cleaned up. The aperture is closed by a conventional loading ramp and a
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
