The Supermarine Swan was designed as a civilian airline, but the sole example was completed as a military reconnaissance aircraft.
The Swan was designed by R.J. Mitchell in response to a possible order from Instone Air Line. In this version it was a sizable amphibian which could carry twelve passengers in the forward part of the hull. The two pilots sat in a raised cockpit mounted between the wings. It was powered by two Rolls Royce Eagle IX tractor engines, carried between the wings. The wings had a span of 68ft 8in, and could fold. It had a monoplane tail, but with three vertical surfaces and rudders.
Although the commercial order wasn't forthcoming, the Air Ministry was interested, and ordered one example to Specification 21/22. This aircraft, N175, was delivered in 1924 and made its maiden flight on 25 March 1924. At this stage it was an amphibian, powered by two Rolls Royce Eagle engines, and with the pilots still in their raised position between the wings.
The aircraft was soon modified. The Eagle engines were replaced with Napier Lion IIBs, the wing folding mechanism and wheels were removed, and it became known as the Swan Mk. II. This version of the aircraft was inspected at Woolston by HRH Edward, Prince of Wales, on 27 June 1924. Photographs from the event show the aircraft rather looming over the Royal party. The aircraft then went to Felixstowe for a series of successful trials.
While this was going on Mitchell had produced a new design for the Swan. This version would have carried two gun positions on the upper wing, a nose mounted gun and bombs under the wings. In later designs the cockpit and bows were streamlined, and finally the cockpit was moved forward.
These modifications were never carried out. Instead the aircraft was returned to Supermarine, and converted into a ten seat passenger aircraft. The passengers were given wicker seats and windows were cut in the fuselage side (presumably in the forward part as originally intended). This civil version of the aircraft made its maiden flight on 9 June 1926 with Henri Baird at the controls and ten passengers (this was presumably felt to be safe because of the long period of flight tests of the basic design). The Swan was then loaned to Imperial Airways, where it was used on the Channel Island route during 1927. In the autumn of 1927 the sole Swan was scrapped.
Although no more aircraft were ordered, the Air Ministry had been impressed with its performance, and this helped Supermarine win Specification R.18/ 24, which led to the successful Supermarine Southampton flying boat.
Engine: Two Rolls Royce Eagle IXs (as built), Two Napier Lion IIBs (as modified)
Power: 360hp each (Eagle), 450hp each (Lion)
Span: 68ft 8in
Length: 48ft 6in
Height: 18ft 3.75in
Empty weight: 7,800lb (Eagle), 9,180lb (Lion)
All up weight: 11,900lb (Eagle), 13,710 (Lion)
Max speed: 92mph (Eagle), 108.5mph (Lion)