.......Climb and maximum level speed performance has been measured on Typhoon IB, R.7700, with 4 x 20 mm. guns fitted, at a weight of 11,070 lb. The position error correction was also measured. The results are summarised below.

(a) Climb performance.
.
Max. rate of climb in M.S. supercharger gear	- 2790 ft/min. at 6,300 ft.
Max. rate of climb in F.S. supercharger gear	- 2000 ft/min. at 17,800 ft.
Time to reach 15,000 ft.	- 6.2 minutes.
Time to reach 25,000 ft.	- 12.4 minutes.
Estimated service ceiling	- 32,200 ft.
Estimated absolute ceiling	- 33,000 ft.
.
(b) Level Speed.
.
Max. true level speed in M.S. supercharger gear	- 376 m.p.h. at 8,500 ft.
Max. true level speed in F.S. supercharger gear	- 394 m.p.h. at 20,200 ft.

1. ...Introduction.

.......Performance trials were required on Typhoon IB, R.7700. This part of the report gives the results on climb and in all-out level flight.

2. ...Condition of aeroplane relevant to tests made.

.......2.1 External details. The aeroplane was fitted with 4 x 20 mm. guns, the muzzles being sealed and the ejection chutes under the wings uncovered.

.......The bullit-proof windscreen was fitted internally and there was no external rear view mirror. The rear hood panels behind the pilot which on previous Typhoons had been of metal, were on this aeroplane of transparent material.

.......An aerial mast passed upwards through this panel, but no aerial was attached. Aerials were fitted between the sides of the fuselage and the tailplane.

.......The exhaust system consisted of six backward facing stub pipes of the lengthened type as shown in the photograph attached to the 8th part of Report No. A.& A.E.E./761,a.

.......2.2 Details of propeller.

Type of propeller	D.H. Hydromatic
Serial No.	A-56024
Diameter	14'-0"
No. of blades	3
Direction of rotation	L.H.
Serial No. of hub	DHA-56024
Serial No. of Blade No.1	BA-234
Serial No. of Blade No.2	BA-383
Serial No. of Blade No.3	CB-532
Basic pitch setting	74 deg.
Pitch range	40 deg.
Course pitch setting	74 deg.
Fine pitch setting	37 deg.
Weight (dry without spinner)	487 1/4 lb.

.......2.3 Loading. The tests were made at a weight of 11,070 lb. with the centre of gravity 8.3 in. foward of the datum, measured with the undercarriage down. The centre of gravity limits are from 9.5 in. to 7.0 in foward of the datum, or to 6.2 in. foward of the datum including the 1% S.M.C. extension.

.......2.4 Engine limitations. The relevant limitations for the Sabre II, obtaining at the time of the test, were:-

		R.P.M.	Boost lb/sq.in.
	Maximum permissible for climb	3500	+6
	Maximum permissible for level flight (5 min. limit)	3700	+7

3. ...Scope of tests.

.......The aeroplane was climbed to 31,000 ft. with the radiator shutter open, at the best climbing speed as found from partial climb tests. This was an inital speed of 185 m.p.h. A.S.I., decreasing by 3 m.p.h. per 1,000 ft above 16,000 ft. Supercharger gear was changed from M.S. to F.S. at 12,600 ft.

.......Maximum level speeds were measured in M.S. supercharger gear between 2,000 and 18,000 ft., and in F.S. gear between 15,000 and 26,000 ft. with the radiator shutter closed. The position error correction was measured by the aneroid method. The position of the pressure head is given in Fig.3.

.......The tests were made between June and September, 1942.

4. ...Results of test.

.......The results of climb and level speed tests have been reduced by the method of A.& A.E.E. Memorandum dated 27th August, 1942 and are given in Tables I and II and Figs. 1 and 2. In calculating the level speeds, in addition to the usual position error and compressibility corrections applied to the air speeds, a further correction has been incorporated which allows for the effect of shock waves on the Mk.VIIID pressure head.

.......The results are summarised as follows:-