|Brief performance trials at combat rating have been completed on this aircraft at a take-off weight of 9260 lb. The principal results at 3000 rpm, +25 lb/sq.in. boost are as follow :-|
|Maximum rate of climb in MS gear||4500 ft/min. at 1600 ft.|
|Maximum rate of climb in FS gear||4000 ft/min. at 13000 ft.|
|Service ceiling (100 ft/min)||39800 ft.|
|Absolute ceiling||40700 ft.|
|Maximum speed in MS gear||419 mph at 5200 ft.|
|Maximum speed in MS gear||455 mph at 17800 ft.|
| The estimated increase in rate of climb below full throttle height due to the use of +25 lb/sq.in. instead of +18 lb/sq.in. boost is about 850 to 900 ft/min., whilst the corresponding increase in all-out level flight is about 26 mph true speed.
1.1 A brief check of the combat performance of this aircraft, which is the first to be fitted with the Merlin 100 (RM.14 SM), was required. This report deals with the measurement of position error, climb and level speed performance trials at the combat rating of 3000 rpm and +25 lb/sq.in. boost. The estimated performance at +18 lb/sq.in. boost is also given.
Provisional results were forwarded to DANA1 by letter dated 29th April 1944.
2. Condition of the aircraft relevant to tests.
2.1 External details.
|Four 0.5 in. machine guns in the wings, ports and ejector chutes sealed with fabric.|
|Camera gun port sealed.|
|Aerial mast and aerial.|
|IFF aerial 14 in. long, ¼” dia. under starboard wing.|
|Aerials from fuselage to each tail plane tip.|
|Strengthened NA multi-stub ejector exhausts with shroud-plates.|
|Air intake under nose just aft of spinner with internal ice-guard about half-way along the air scoop.|
|Coolant and oil cooler radiator intake under fuselage in the normal position for Mustang aircraft. In accordance with U.S.A. recommendations the “fully closed” position of the exit duct flap was adjusted by a stop on the operating lever, to give a minimum opening of 7 ¼” (i.e. 2” more than the normal value).|
|Note: Photographs of this aircraft were not obtained, but reference may be made
to photographs of Mustang III FX. 953 (9th Part of Report No. A. &A.E.E. /781c) which was similar in external features with the exception that some aerials were not fitted.
2.2 Pressure head details. Details of the underwing Kollsman pitot-static head are given in Fig. 1.
2.3 Loading. The take-off weight of the aircraft was 9260 lb. and the C. of G was at 99.9 ins. aft of the axis of reference. This corresponds to typical service loading, with no external bombs or fuel tanks carried.
2.4 Engine numbers and limitations.
|Merlin 100, Nos. 90353/A505163.|
|The relevant limitations are as follows:-|
|Climb (combat) 5 mins. limit||3000||+25|
|All-out level, 5 mins. limit||3000||+25|
| All trials were done using 150 grade fuel to specification RDE/F/290.
2.5 Propeller details.
Hamilton hydromatic, 4 metal blades, diameter 11’2”.
3. Scope of tests.
3.1 The position error correction was measured by the aneroid method, in level flight, with flaps and undercarriage retracted, over a speed range from 140 mph to 420 mph IAS.
3.2 Performance on the climb at combat rating was measured, using best climbing speeds estimated from partial climbs on a similar Mustang III aircraft, FX.953. Owing to the high initial climb and low gear change altitude, MS and FS gear climbs were done separately but this Report gives the results when changing gear at the best height for optimum performance.
3.3 Level speeds at combat rating were done from 2000 feet to 38,000 feet.
These performance results have been corrected to ICAN standard conditions by the methods of Report No. A. & A.E.E./Res/170, using a supercharger constant of 0.002 and the results of the level speed tests have also been corrected to 95% of the take-off weight by the method of the same Report. The compressibility correction has been calculated by the methods given in Addendum to Report No. A. & A.E.E./Res/147 and a strut correction, based on the results of ARC 6420 was also applied to the ASI reading.
4.1 P.E.C. Fig. 2 gives the position error correction and Fig.3 the correction to the altimeter when connected to the static head. The P.E.C. varies linearly from -20.9 at 420 mph IAS to -8.4 at 240 mph IAS. The correction is zero at 177 mph and +4.6 at 140 mph IAS. This agrees within 2 or 3 mph, with the P.E.Cs measured on two Mustang I and one Mustang X aircraft.
4.2 Combat climb. Fig.4 and Table I give boost, rate of climb, ASI, and time to height at combat rating. The maximum rate of climb is 4500 ft/min. in MS gear, up to 1600 feet, and 4000 ft/min. in FS gear, at 13,000 ft.
It is estimated that use of +25 lb/sq.in. instead of +18 lb/sq.in. increases the maximum rate of climb by 900 ft/min. in MS gear and 850 ft/min. in FS gear.
4.3 Combat level speed. Fig.5 and Table II give level speed results at combat rating. Results are estimated for comparison at a maximum boost of +18 lb/sq.in. The salient points are as follow:-
|Top Speed||+18 lb/sq.in.||+25 lb/sq.in.|
|a) in MS gear||419 mph at 10,800 ft.||419 mph at 5,200 ft.|
|b) in FS gear||452 mph at 23,500 ft.||455 mph at 17,800 ft.|
|Use of +25 lb/sq.in. instead of +18 lb/sq.in. boost increases the maximum speed below the full throttle heights by 26 mph.
4.4 Propeller tip Mach numbers on all-out level speeds exceed 0.9 over most of the height range.
The values are:-
(based on standard conditions)
|MS gear 5,200 ft.||0.88||0 to + 2°C|
|FS " 17,500 "||0.96||-24 to -19°C|
|" " 25,000 “||0.97||-40 to -34°C|
|" " 30,000 “||0.99||-53 to -48°C|
|" " 35,000 “||1.00||-62 to -58°C|
|Owing to the brief nature of the trials, it was not possible to check the effect of RPM on level speed but this is in progress on Mustang III FX. 953 and a report will be issued later.|
Combat climb performance
3000 RPM Weight 9260 lb.
Radiator and oil cooler flaps fully open
|Height||Rate of climb|
|Time to Height|
|*||Full throttle heights|
|Service ceiling||39,800 feet|
|Absolute ceiling||40,700 feet|
Combat level speed performance
Corrected to 95% take-off weight = 8800 lb.
Radiator and oil cooler flaps at minimum opening
|2000||404||416||-21¼||- 1½||+ ¼||+25.0||MS|
|4000||413||413||-21||- 2¾||+ ½||+25.0||||
|5200*||419||412||-21||- 3¼||+ ½||+25.0||||
|6000||419||407||-20½||- 3¾||+ ¾||+23.9||||
|8000||419||395||-19½||- 4½||+ ¾||+21.4||||
|9000||419||389||-19||- 5||+ 1||+20.1/+25.0||MS/FS|
|10000||423||387||-18¾||- 5¼||+ 1||+25.0||FS|
|12000||431||382||-18½||- 6¼||+ 1¼|||||||
|14000||439||377||-18||- 7||+ 1¾|||||||
|16000||447||373||-17½||- 8¼||+ 2|||||||
|17800*||455||369||-17¼||- 9¼||+ 2¾||+25.0||||
|32000||438||276||- 9½||-10½||+ 2½||+ 8.7||||
|34000||432||261||- 8¼||-10||+ 2½||+ 6.6||||
|36000||425||247||- 7||- 9¾||+ 2¼||+ 4.8||||
|38000||416||230||- 5½||- 8¾||+ 1¾||+ 2.8||||
|*||Full throttle heights|
|D.D.R.D.A.||D.P.C.A. (3 copies)|
|A.C.A.S. (T.R.)||O.C. Handling Sqdn.|
|D.R.A.E. (5 copies)||R.T.P. (TIB) (6 copies +1)|
|R.D.T.3.||R.T.P.2(a) (35 copies)|
|A.D.D.A.N.A. (2 copies 1 for action)||RTO AST Hamble|
|D/DED||Rolls-Royce Berby (4 copies)|
|CTA/DED pass to A.D.R.D.E.1.||Rolls-Royce,Hucknall (2|
WWII Aircraft Performance Mustang Performance