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 modifications 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 massive 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 repayment 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.

The design of the AS.6 Envoy, began in late 1933 as and Hessell Tiltman, the technical director and chief designer based it on the Courier and using as many common parts as possible and their new Javelin or the Wolseley A.R.9 engine. T. Neville Stack was finally content with a Cheetah-engined machine with a cruise speed of 180 mph and endurance of six hours.

Tiltman followed the same basic construction as the Courier. The airframe was of wooden construction, the fuselage was a semi monocoque structure in two sections, the front fuselage comprising the cockpit, cabin, toilet and luggage compartment and the rear fuselage carrying the tail unit. The doors and windows were built integrally with the sides and the stressed ply skin cut away before assembly. All the major fuselage sections were jig built with longerons of spruce and a skin of birch ply laid at an angle of 450. No diagonal bracing was needed, as the skin carried all the shear loads, bending loads being carried by the longitudinal members.
The fuselage shell comprised two sides, a bottom and a top panel, to form a light, rigid box. The top and bottom curvature was formed with formers and stringers covered in fabric. With accommodation for a pilot and eight passengers the Envoy had all control surfaces fabric-covered, and a retractable tailwheel type landing gear and a variable-incidence tailplane were fitted.

Three versions were produced. The Series 1 and 2 Envoys had a twin spar wing with Warren girder inter spar bracing. The leading edge was covered by 1mm ply, and the wing was fabric covered. It was stiff in torsion and was complicated to build. The Series I (17 examples built) was without trailing-edge flaps; the Series II (13 built) introduced hydraulically operated split flaps which extended from the aileron to wing root on the trailing edge of each wing, and also from wing root to wing root beneath the centre-section. With flaps down the stalling speed was reduced by 11 mph (177 kph). The Series III (19 built) was similar, but had a number of detail improvements. The Series 3 Envoy, introduced at the end of 1936, was built with a ply-covered wing, the two spars forming a torsion box to eliminate the Warren girder bracing and give a stronger and stiffer wing. The production time for the wing was reduced by 35 40 percent. The tail unit was a wooden structure, fabric covered. The undercarriage, operated by a hydraulic handpump, was geometrically and functionally similar to the Couriers.

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 decided to identify it as the A.S.8, to be known as Viceroy.

Soon after the 1934 SBAC Show at Hendon, Tiltman received from the Air Ministry an in¬vitation to tender for an Envoy con¬verted to a Coastal Patrol aircraft. Nothing more was heard of the project.

The prototype first flew on 26 June 1934 and 50 were built, including the pro¬totype, by Airspeed for British, Japanese, Czechoslovakian, and Chinese. South Africa acquired seven En¬voys in 1936: three of these were used by the SAAF and had an armament com¬prising a forward firing machine-gun and a dorsal gun turret. The four civil Envoys which made up the total, and which were for operation by South African Air¬ways, were capable of quick conversion for use in a military role. A small number were supplied to the RAF. A number were used in the Spanish Civil War. Mitsubishi also built a number under licence.

Engines fitted to Envoys included the Wolseley AR.9, Scorpio I or Aries III, Armstrong Siddeley Lynx IVC or Cheetah IX, Wright Whirlwind R.760 and Walter Castor II.

AS.6
Engine: 2 x Wolseley AR.9, 149-kW (200-hp)

AS.6A
Engine: 2 x Armstrong Siddeley Lynx IVC, 179-kW (240-hp)

AS.6D
Engine: 2 x Wright R-760-E2 Whirlwind 7, 261 -kW (350-hp)

AS.6E
Engine: 2 x Walter Castor II, 254-kW (340-hp)

AS.6G
Engine: 2 x Wolseley Scorpio I, 186-kW (250-hp)

AS.6H
Engine: 2 x Wolseley Aries III, 168-kW (225-hp)

AS.6J
Engine: 2 x Armstrong Siddeley Cheetah IX, 261-kW (350-hp)
Maximum speed at 2225m (7,300ft): 338 km/h / 183 kts / 210 mph
Cruising speed at 3050m (10,000ft): 290 km/h / 157 kts / 180mph
Service ceiling 6860m (22,500ft)
Range: 1046 km / 565 nm / 650 miles
Empty weight: 1840kg (4,057 lb)
Maximum take-off weight: 2858 kg (6,300 lbs)
Wing span: 15.95m (52ft 4in)
Length: 10.52m (34ft 6in)
Height: 2.9m (9ft 6in)
Wing area: 31.49 sq.m (339sq.ft)
Wing load: 18.66 lb/sq.ft / 91.0 kg/sq.m

A.S.6Jc Envoy III
Engines: 2 x Armstrong Siddeley Cheetah A.S.9, 375 hp
Span: 52 ft 4 in
Length: 34 ft 0 in
Height: 9 ft 6 in
Empty weight: 4340 lb
Loaded weight: 6600 lb
Max speed: 203 mph
Cruise: 170 mph
Range: 620 mi

AS.6JM/C
Engine: 2 x Armstrong Siddeley Cheetah IX, 261-kW (350-hp)
Take-off weight: 2960 kg / 6526 lb
Empty weight: 1920 kg / 4233 lb
Wingspan: 15.9 m / 52 ft 2 in
Length: 10.5 m / 34 ft 5 in
Height: 2.8 m / 9 ft 2 in
Wing area: 31.5 sq.m / 339.06 sq ft
Max. speed: 325 km/h / 202 mph
Cruise speed: 270 km/h / 168 mph
Ceiling: 6700 m / 22000 ft
Range: 990 km / 615 miles
Crew: 2
Passengers: 6

A light transport of conventional all-wood construction, with all control surfaces fabric-covered, of 1935. The first British aircraft with retractable undercarriage to go into production, a five-six-seat cantilever low-wing cabin monoplane.

First flown on 11 April 1933 (G-ABXN) from Portsmouth, four days later it crashed at Portsmouth, receiving minor damage. Repaired, it had another accident at RAF Martlesham Heath. It was used in aerial refuelling experiments by Sir Alan Cobham, using two Handley Page W10s as aerial tankers. The experiments led to an attempt of a non-stop flight to India that started at Portsmouth on 24 September 1934. It ended the same day when Cobham had to make a forced landing at Malta, due to a broken throttle; in the event the Courier was damaged. The aircraft was impressed into the RAF in June 1940, s/n X9427.

Sixteen were built with a total of 15 production aircraft.

Gallery

AS.5A
Engine: Armstrong Lynx IVC

AS.5B
Engine: Armstrong Siddeley Cheetah V, 301 hp
Length : 28.51 ft / 8.69 m
Wingspan : 47.014 ft / 14.33 m
Wing area : 250.048 sqft / 23.23 sq.m
Max take off weight : 3999.9 lbs / 1814.0 kg
Weight empty : 2328.5 lbs /1056.0 kg
Max. speed : 144 kts / 266 km/h
Cruising speed : 126 kts / 233 km/h
Service ceiling : 16995 ft / 5180 m
Wing load : 15.99 lb/sq.ft / 78.00 kg/sq.m
Range : 556 nm / 1030 km
Crew : 1