Spitfire VIII Conversion JF.319
Level Speed Tests With Griffon R.G.5.S.M. Engine
18 lb/sq. in. Boost Rating
Summary of Results
At the all up weight for the Spitfire XIV i.e. 8400 lb. and at 18 lb/sq.in. and 2750 r.p.m., the results are:-
(a) Maximum level speed in F.S. gear, 447 m.p.h. at 25600 ft.
|Level Speeds and Boost
Spitfire F. Mk. VIII(Conv) (Prototype Mk.XIV) JF.319
Climb and level speed performance and position error
|(i) On the climb at combat rating.|
|Max. rate of climb in MS supercharger gear||5,040 ft/min. at 2,100 ft.|
|Max. rate of climb in FS supercharger gear||3,550 ft/min. at 22,100 ft.|
|(ii) In all-out level flight.|
|Max. true air speed in MS supercharger gear||391 mph at 5,500 ft.|
|Max. true air speed in FS supercharger gear||446 mph at 25,900 ft.|
|Performance on Climb at Combat Rating|
|Level Speed Performance|
Spitfire XIV low altitude speed at +21 lbs./sq.in.
20 July 1944
Speeds of F.Mk. XIV (Griffon 65)
Spitfire XIV RB.176
Top level speed at +25 lbs/sq.in. Boost
Climb and Level Speed Performance (+18 Boost)
Maximum Climbing Performance
Level Speed Performance
|Comments from No. 610 Squadron ORB relating to performance of Spitfire XIV
Climb and Speed at +18 lbs Boost Supermarine, October 1944. There was much discussion during the summer and fall of 1944 between the Air Ministry, Supermarine and Rolls-Royce as to whether, for production reasons, the Spitfire XIV should switch to a .45 reduction gear to match that of the Spitfire 21 or retain the .51 gear. It was decided that the advantages of the .51 were such that it would be retained for the Spitfire XIV.
Technical Note No.Aero.1501(Flight) Improvement of Performance of Fighter Aircraft Operating Against the German Flying Bomb
610 Squadron Operations Record Book, July 1944 - "21 lbs boost on 150 octane petrol"
610 Squadron Operations Record Book, 6 September 1944: First operation over Germany by Spitfire XIV Wing comprised of 350, 402 and 610 squadrons.
402 Squadron Operations Record Book, 26 February 1945 - "150 grade fuel"