https://en.wikipedia.org/wiki/Supermarine_Seafang
"Drawing-board design
In 1943, as the design of the Spiteful was developing, Supermarine presented a brochure to the Air Ministry describing a "High-Performance Aeroplane for the Royal Navy", also known as the Supermarine 391. This design was intended to be used as a carrier-borne fighter, with a secondary role as a strike aircraft, able to carry an 18-inch (45.7 cm) Mark XV aerial torpedo. Bombs or rockets could also be carried and the fixed armament was four Hispano Mk. V 20mm cannon. The 391 used the Spiteful/Seafang wing and undercarriage mated to a wide centre-section incorporating leading edge air intakes feeding the coolant radiators for a 3,550 hp, 24 cylinder 46-H-24 (later known as the "Eagle"); this engine drove contra-rotating, four-bladed propellers. The fuselage was longer with a redesigned fin and rudder unit.
Specifications for the 391 include a wingspan of 43 ft 6 in (13.3 m), a fuselage length of 39 ft 9 in (12.1 m) and a wing area of 335 ft² (31.2 m²). Maximum weights were 15,750 lb (7,144 kg) as a fighter and 17,250 lb (7,825 kg) when armed with a torpedo. The maximum speed was projected to be 546 mph (879 k/mh) at 25,000 ft (7,620 m)."
http://www.whatifmodellers.com/index.php/topic,18267.0.html
https://www.rcgroups.com/forums/showthread.php?287752-Mystery-Aircraft/page937
Eagle engine(Sleeve vaule engine with two stage two speed mechanical supercharger and intercooler). I can't find exhaust nozzles in type 391 drawing. ??? Covered by plate? I want to know the position of engine exhaust gas outlet which perhaps located behind the radiator cooling air intake. Wyvern's engine cooling system design is interesting.
http://www.modelenginenews.org/gallery/croft/eagle/index.html
http://plane-crazy.k-hosting.co.uk/Aircraft/Props/Wyvern/westland_wyvern.html
https://www.youtube.com/watch?v=6_V2HqAZzms