Airspeed AS.8 Viceroy
In parallel with the design work on the Envoy, Tiltman was also working on the Cheetah-engined machine for Stack. This required so many variations from the basic Envoy that it was designated the A.S.8 Viceroy.
A batch of six machines was laid down, the initial flight test of the prototype, G-ACMT, being scheduled for April 1934. Maximum effort was made on the prototype, but modifica-tions to the airframe and the complexity of building with different engines caused much delay. At Farnborough deep prejudice existed over cantilever wings, and they demanded a 25 per cent increase in the load factor. After four months negotiation, and Tiltman testing a complete wing to destruction proved this increase was unnecessary.
On June 26, 1934, FIt Lt C. H. S. Colman, Airspeed's test pilot, flew 'CMT for the first time. It handled extremely well with no snags, and was demonstrated at the Society of British Aircraft Constructors' Show at Hendon on July 2.
The certification trials at Martlesham Heath were troubled, mainly with the Wolseley engines, in which two fuel pump spindles sheared. A failed gasket in the hydraulic system caused the machine to land with one undercarriage leg half down, with consequent damage and delay, and the fuel tanks developed leaks. The major problem, was that the machine was overweight, and its single-engine performance was not satisfactory. It was felt that the new Wolseley IB engines would cure this defect. Generally, the test pilots were extremely impressed with the handling and performance of the Envoy, and a Certificate of Airworthiness was, issued on October 9, 1934.
All entries in the Australia Race had to be handed over to the Royal Aero Club scrutineers by October 14. The manufacturers of the Viceroy's engines and automatic pilot failed to keep their delivery promises, and the machine did not fly until September 19. To add to Airspeed's problems, the engine revs were low and the weight high. Its 315 hp Cheetah VI engines gave it a top speed of 210 m.p.h. (338 km/hr) at 7,000ft (2,135m). It cruised at 190 mph (306 km/hr) and, with a mas-sive long range fuel tank in the cabin, had a range of 1,400 miles (2,253km).
To save time, a Martlesham test pilot flew to Portsmouth to carry out the C of A trials. The machine was completely satisfactory and displayed a top speed of 210 mph (338 km/hr).
The MacRobertson Race to Australia was in two sections, absolute speed and handicap with a maximum elapsed time. The Viceroy was so heavily handicapped as to have virtually no chance of success. Stack's Viceroy was forced down at Abbeville in Northern France with electrical trouble. The weather was foul. He soon took off again for Marseilles, but returned almost immediately. During the evening of October 20 he left for Rome, reached Athens and withdrew from the race. At the end of 1935 Stack and Turner sued Airspeed for "the recission of a hire purchase agreement and repay-ment of £2,448 paid by them for the Viceroy." They alleged that Airspeed had been negligent in failing to ensure that the aircraft was fully airworthy. The case was settled out of court, the plaintiffs withdrawing all their allegations and agreeing to return the Viceroy to the Company with a further payment of £1,850.