1.   Introduction.

            Level speed tests have been carried out on Spitfire VIII Coversion JF.319 fitted with a Griffon R.G.5.S.M. engine, 18 lb/sq.in. boost rating. Externally this aircraft was in a Spitfire Mark XIV condition.

2.   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.
(b)   Maximum level speed in M.S. gear, 389 m.p.h. at 6000 ft.

3.   Condition of Aircraft

(a)   Griffon R.G.5.S.M. engine No. 1282 fitted. This engine is cleared for 18 lb/sq.in. boost and has a .51 airscrew reduction gear.
(b)   10 ft. 5 in. dia. 5 blade Jablo Rotol airscrew, type R.19/5F5/1. Faired root blades to Drg. No. RA.10130
(c)   Mark XIV cooling systems as follows:

(d)   Tropical type of air intake to Drg. No. 35638 Sht. 35 was fitted without a filter or by-pass shutter.
(e)   Multi-ejector exhausts fitted.
(f)   Production windscreen (flat front panel) with streamline rear view mirror fitted.
(g)   T.R.1143 whip type aerial fitted.
(i)   Large fin (straight leading edge) with trimmer-cum-balance tab fitted to rudder.
(j)   2 cannon, 4 Browning armament with gun ports sealed.
(k)   All up weight to represent Spitfire XIV i.e. 8400 lb. C.G. 4.1 inches aft of datum.

4.   Reduction of Results

            Results have been reduced to I.C.A.N. standard conditions in accordance with A.P. 970. Chap. 1000 para. 23.

5.   Engine Limitations

            Maximum for all out level: 5 minutes duration 18 lb/sq.in. boost at 2750 r.p.m.

6.   Results

            The level speed results are given on the attached curves.