The Hurel-Dubois Miles HDM.105 was a transport aircraft fitted with very high aspect ratio wings for research purposes, building on research carried out with the Hurel-Dubois HD.10, and a stepping point to the planned production HDM.106 Caravan. The HDM.105/HDM.106 provided the starting point for the design of the Short SC.7 Skyvan.[citation needed]
Design and development
Maurice Hurel [fr], a French aircraft designer, became a champion of very high aspect ratio wings in a bid to significantly reduce induced drag, similar to the "Davis wing" of the Consolidated B-24 Liberator, but with much higher aspect ratios. After testing his wing design on the diminutive HD.10, Hurel was ready to progress to a full size transport aircraft, a joint venture between F.G. Miles Ltd. and Hurel-Dubois [fr], fitting a Miles Aerovan with a very high aspect ratio wing and carrying out comparison tests.[1]
The HDM.105 utilised the fuselage, tail unit and engines from Miles Aerovan Mk.4G-AOJF, fitted with a Hurel designed 75 ft 4 in (23 m) span 20.5:1 aspect ratio wing of NACA laminar flow sections, supported on aerofoil section lifting struts. The wings were fitted with double-slotted flaps actuated by Miles electric actuators from the original Aerovan. Roll control was by differential ailerons and inter-connected upper-surface spoilers. With no room for fuel in the slender wings, 13 imp gal (16 US gal; 59 L) fuel tanks were fitted in the vertical undercarriage strut fairings.[2]
Operational history
The HDM.105, with B-class registration G-35-3 (subsequently re-registered G-AHDM), was first flown on 31 March 1957 by I.A. Forbes, but was later damaged beyond repair in a landing accident at Shoreham on 28 June 1958 and dismantled.[2]
Variants
HDM.106 Caravan
Following the successful testing of the HDM.105 the joint company H.D. et M (Aviation) Ltd, was established to exploit derivatives. The HDM.106 Caravan was to have been an all-metal 8,000 lb (3,629 kg)transport aircraft, with 75 ft (23 m) span wings, powered by 2x 290 hp (216 kW) Lycoming GO-480, 2x 340 hp (254 kW) Lycoming GSO-480B or 2x 320 hp (239 kW) Turbomeca Astazou I engines, but the HDM.106 did not progress beyond the drawing board with H.D.
et M (Aviation) Ltd.[3][4]
The design for the HDM.106 was sold to Shorts who developed it into the very successful Short SC.7 Skyvan, but with a much reduced, moderately high, aspect ratio of 11:1.[2]
HDM.107 Aerojeep
The H.D.M.107, known as the Aerojeep, was a military version of the HDM.106 to a STOL light transport requirement of the US Army, to be powered by two 800 shp (597 kW) Lycoming T53 turboprop engines.
The Miles M.111 was proposed as a light single-engined transport utilising the outer wings and struts of the HDM.105, powered by a single 320 shp (239 kW) Turbomeca Astazouturboprop engine.[2]
Specifications (HDM.105)
Data from Flight : Foretaste of the Caravan - HDM.105 handling HDM.106 prospects,[1] Jane's All the World's Aircraft 1958-59,[4] Miles aircraft since 1925[2]