The Airspeed AS.39 Fleet Shadower was a British aircraft intended for long-range patrol missions, but unfortunately, it never progressed beyond the prototype phase.
Another aircraft, the General Aircraft Fleet Shadower, was also developed as a prototype.
Despite the potential of the fleet shadower concept, both designs were quickly surpassed by advancements in airborne radar technology during wartime.
The Royal Navy identified a requirement (Operational Requirement OR.52) for an aircraft that could monitor enemy fleets during nighttime, leading to the creation of Specification S.23/37.
This specification demanded an aircraft that was slow-flying, low-noise, and had a long range, suitable for deployment from an aircraft carrier’s flight deck.
The specified performance criteria included maintaining a speed of 38 knots (70 km/h) at an altitude of 1,500 ft (460 m) for a minimum of six hours.
Five firms expressed interest: Percival, Short Brothers, Fairey Aviation, General Aircraft Ltd, and Airspeed.
General Aircraft proposed the G.A.L.38, which shared a close resemblance in general design to the AS.39.
General Aircraft and Airspeed were chosen to construct two prototypes each, with Airspeed being awarded a contract on August 10, 1938.
The AS.39 was a monoplane with a high-wing, semi-cantilever design.
Its wings and tail unit were made of wood, while the fuselage was constructed with an all-metal monocoque structure.
The outer panels of the wings were strut-braced, providing additional support.
The landing gear was of a fixed, divided type, and it had a tailwheel.
This observation aircraft was designed to accommodate a crew of three individuals, including a pilot, observer, and radio operator.
The unique crew configuration featured the observer positioned in the nose, which had clear-vision windows on three sides.
The pilot’s compartment was raised to allow passage to the radio operator’s compartment.
To enhance performance, four small Pobjoy Niagara V seven-cylinder air-cooled radial engines, each with a power output of 130 hp (97 kW), were mounted on the wings.
This arrangement ensured that the propwash over the wing was maximised, resulting in increased lift at low speeds.
Additionally, the wings were designed to be foldable, enabling storage when the aircraft was used on an aircraft carrier.
Out of the two prototypes that were initiated, only one managed to reach completion.
Its inaugural flight, however, faced a delay on 17th October 1940 due to complications arising from the Niagara V engines, which were plagued by a vibration issue.
The prototype encountered challenges in terms of stability and handling during stall situations, exacerbated by the engines’ lack of power.
In response to a proposal, Airspeed was approached to consider re-engineering the aircraft with two Armstrong Whitworth Cheetah XI radial engines, along with the addition of rear-facing machine guns.
Although only a preliminary proposal had been put forth, the second aircraft remained unfinished.
On 17th February 1941, the Navy terminated the fleet shadower program, including the AS.39, and instructed the company to dismantle both aircraft.
Meanwhile, the competing G.A.L.38 managed to stay airborne for a few months before it too was cancelled and subsequently scrapped in March 1942.
The requirement for such aircraft had become obsolete with the advent of radar technology in long-range patrol aircraft like the Liberator I.
Specifications
Crew
3
Length
39 ft 10 in (12.14 m)
Wingspan
55 ft 4 in (16.87 m)
Height
10 ft 5 in (3.18 m)
Wing area
469 sq ft (43.6 m2)
Empty weight
4,592 lb (2,083 kg)
Gross weight
6,935 lb (3,146 kg)
Powerplant
4 × Pobjoy Niagara V,
7-cylinder air cooled radial piston engines,
140 hp (100 kW) each
Performance
Maximum speed
126 mph (203 km/h, 109 kn) at 5,000 ft (1,524 m)
Cruise speed
113 mph (182 km/h, 98 kn) at 5,000 ft (1,524 m)
Stall speed
33 mph (53 km/h, 29 kn)
Endurance
6 hours
Service ceiling
14,700 ft (4,500 m)
Absolute ceiling
16,700 ft (5,090 m)
Rate of climb
865 ft/min (4.39 m/s)
Time to altitude
10,000 ft (3,048 m) in 18 minutes.
Sources
Airspeed Aircraft Since 1931-H.A. Taylor.
The World’s Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters-Jim Winchester.
National Museum of the Royal Navy, Fleet Air Arm Museum.
