One major problem with the design of the Hawker Tempest and Typhoon aircraft was that they had a large ‘chin’ radiator. If another aircraft got into trouble it could belly flop land, in a field for example, and slide along the ground to a standstill. The chin radiator fitted to Napier Sabre powered aircraft meant that any such landing was much more risky because it would make contact with the ground first, dig in and flip the aircraft over.
Napiers spent a great deal of time researching and developing a range of solutions. The requirement was to allow sufficient airflow across the radiator with adjustment to correctly regulate the cooling. This increased as the engine Series was developed and required extra cooling.
The solution was to create an annular radiator allowing air to pass through the spinner of the aircraft. As can be seen in the images several types of annular radiator were tested and developed. In reality very few Sabre engined aircraft actually received this modification die to the war ending. The unique Vickers Warwick HG248 was the only twin engined Sabre aircraft and it had annular radiators.
Source:
https://npht.org/napier-sabre-annular-radiator/As part of the power plant testing, Napier had developed a unique annular radiator for use on the Tempest, in an effort to streamline the aircraft by doing away the big scoop radiator.
The radiator development program used two modified Tempest Mk. V, serials EJ518 (fitted with a Sabre VI) and NV 768. NV 768 was later fitted with a ducted spinner with the same diameter as the fuselage and, although test flown, the spinner was not actually planned for use on production Tempests. Neither feaure was incorporated onto Tempest production line and the aircrafts were scrapped after the war.
Much more detail here:
https://www.key.aero/article/playing-it ... nd-tempest
Hawker Tempest V NV768 experimentally fitted with a ducted spinner and an annular radiator.








