The Boulton Paul P.122 was a design for a rocket powered interceptor, designed in response to Specification F.124T.
Specification F.124T called for a small rocket powered bomber interceptor, to defend against the new generation of high speed Soviet bombers. The aircraft would have to have a very high rate of climb and good high altitude performance, and be able to glide back to land after the fuel was expended.
The P.122 (and most of its rivals) would have been powered by the 8,000lb thrust Armstrong Siddeley Screamer variable thrust rocket. The Screamer used methanol, water and liquid oxygen fuel.
The P.122 was a twin-boom aircraft, with its cannon armaments carried in extensions of the booms in front of the wings. It didn't have a conventional undercarriage, and instead took off from a jettisonable trolley and landed on a skid built into the fuselage.
The P.122 was estimated to have a very impressive rate of climb, but the entire project came to nothing after Saunders-Roe produced a similar type of aircraft but with a small turbo-jet engine to allow for a controlled return to land. The Air Ministry decided to add this to the specification, and later asked Saunders-Roe to built two prototypes of their S.R.53 design.
Engine: Armstrong Siddeley Screamer
Power: 8,000lb thrust
Span: 21ft 7in
Length: 36ft 7in
Climb Rate: 1.4min to 10,000ft; 2.3min to 40,000ft; 3min to 60,000ft
Armament: At least two cannon