Prototype Seafire F.45 TM379
Changes for naval service were confined to the addition of an arrester hook, slinging points and the substitution of a naval radio set.
The F.45 aircraft featured the 60-series Griffon engine, the first to have a two-stage, two-speed supercharger. The modified Spitfire F.21 prototype TM379 was used for conversion work by Cunliffe-Owen and fitted with a “sting” arrestor hook and slinging points for the catapult. In order to avoid the doors fitted to the main undercarriage legs from snagging the arrestor wires, they had to be shortened, while those fixed to the wheel bay were lengthened to compensate. TM379 underwent testing in October 1944 and was later tested with contrarotating propellers on April 10, 1945. Two more Spitfires, TM383 and TM389, were contracted in July 1944 for conversion into navalized form, but TM389 was later cancelled. The F.45 was considered an interim aircraft as it had a non-folding wing, and only 50 airframes were manufactured, all from Castle Bromwich and considered development and training machines rather than operational aircraft. They were not expected to be used in frontline units. The serial numbers for the F.45s were LA428 to LA457 and LA480 to LA499.