De Havilland DH 85 Leopard Moth
Following a series of fatal wing failures and the resulting bad press concerning the initially very popular and successful D.H.80 Puss Moth, Geoffrey de Havilland set about redesigning the basic airframe which resulted in the D.H.85 Leopard Moth. Although similar in appearance the aircraft was superior overall. A spruce and plywood fuselage was chosen over welded steel tube construction. The timber airframe was not only cheaper to manufacture but was also lighter, the improved gross to tare weight ratio allowing a third passenger to be carried in a side by side arrangement behind the pilot. This produced a wider slab sided fuselage in the early models, however this was later addressed by longitudinal stringers on the outside of the fuselage and applying a fabric covering. The tapered and thinner fabric covered wing allowed a faster cruising speed (118 mph/ 1 90km/h at 1,000 ft/304 m), but also meant a higher landing speed. The principal way of visually distinguishing between the two aircraft was the position of the main undercarriage compression legs. The Puss Moth’s main legs were anchored at the top of the front windscreen, whereas these legs only travelled as high as the base of the windscreen frame on the Leopard Moth. These legs could be rotated through 90 degrees to serve as a rudimentary air brake, this action reducing air speed by about 35 mph (56 km/h). These steepened the glide angle from 12-1 to 9-1. The 2 gallon (9 litre) oil tank also moved from an external position in the Puss Moth, to behind the firewall in the Leopard.
An initial batch. of six machines were built at de Havilland's Stag Lane facility, a cautious approach adopted until a first flight could be undertaken and the design could prove its worth. Powered by a 4 cylinder inline air- cooled 130 hp D.H. Gipsy Major driving a two blade fixed pitch propeller, the prototype (G-ACHD) made its first flight on 27 May 1933 at Stag Lane piloted de Havilland for a 20 minute flight.
It was later in the calm of the evening that the remarkable stability of the D.H. 85 was revealed. When flying with the chief engineer Bob Hardingham, de Havilland left the controls and joined Bob in the passenger seat, only being obliged to lean over an adjust the trim once. It was obvious that design was worth pursuing and marketing efforts were spooled up. Included in this effort was an offer to private owners that would see an entirely new (to aviation at least) maintenance service offered. An owner could opt to take advantage of fixed charges for servicing and overhaul required for the Certificate of Airworthiness - all of which would be carried out by de Havilland's own engineering staff.
Geoffrey de Havilland flew the prototype, which he retained for his private use, to victory in the 1933 running of the King's Cup Race, clocking an average speed of 139.51 mph (224.51 km/h). The two other Leopard entries (G-ACHC and G-ACHB) came in third and sixth in what was an impressive performance from the new type.
Orders started coming in from both the private sector and business owners and consequently serious production got underway at Stag Lane and thereafter Hatfield, over the next three years. The first 30 aircraft featured a slab side fuselage, but later aircraft were fitted with stringers which ‘padded out’ the sides. During this time 132 examples were built, 71 of which operated in the UK. Several of these undertook long range flights to such diverse destinations as the Cape Verde Islands, Timor and Australia, the latter as a survey flight prior to the MacRobertson Air Race in 1934 when G-AC1X flew an outbound trip lasting 15 days. It almost halved that on the return leg and in doing so set a record of eight days, 12 hours. It was from Australia again that one of the last of these types of flights occurred when 'Jimmy Broadbent flew VH-AHB from Darwin to Lympne on 3rd May 1937 in just over six days.
A total of 61 examples were built for export, mostly as self assembly kits and were spread throughout the world from India to South Africa and from Switzerland to Argentina.
The price of a DH 85 in the 1930s was £1125.
As with many civil aircraft, Leopard Moths were conscripted into RAF service at the outbreak of WW2, 44 being impressed into the communications role whilst those in the Commonwealth found themselves similarly employed.
Following an accident that saw Geoffrey de Havilland's G-ACHD come off second best after a run in with a brick wall during a servicing incident, the aircraft was handed over to the Engine Division for use as a test bed for the new 200 hp Gipsy Six which was heavier and longer than the Major. This was compensated for by reducing the sweep back of the wings and moving the wheels fractionally forward. Designated the D.H. 85A, engine tests continued for 20 hours before a flight was made on 23rd October 1933. Prior to the MacRobertson Air Race G-ACHD was again anchored to the ground for some 500 hours of trials of a Gipsy Six fitted with both Ratier and Hamilton props were tested from May to August 1934 when the engine was finally granted approval. It ended its days undergoing icing trials, eventually being scrapped by the end of 1940.
Three years' production, initially at Stag Lane and then at Hatfield, totalled 132 examples.
De Havilland DH.85 Leopard Moth