(1)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito F. Mk. II. W-4076.
(2 x Merlin 21's)
Level speed measurments made with matt and smooth black finishes
Table I
Level speed measurments with matt black finish (RDM/2A).
| Height in standard atmosphere (feet) | True Air speed (M.P.H.) | A.S.I. Ø m.p.h. | Position error correction m.p.h. | Compressibility correction m.p.h. | (Mean) | Boost lb/sq.in. (Mean) | Supercharger gear |
|---|---|---|---|---|---|---|---|
| 18,000 | 345.5 | 245 | +19.1 | -4.5 | 3000 | 8.3 | F.S. |
| 20,000 | 352.5 | 243.5 | +18.8 | -5.0 | " | 8.3 | " |
| 21,400* | 358 | 241.5 | +18.7 | -5.4 | " | 8.3 | " |
| 22,000 | 357 | 239 | +18.4 | -5.5 | " | 7.8 | " |
| 24,000 | 354 | 229.5 | +17.6 | -5.6 | " | 6.4 | " |
| 25,000 | 352 | 224.5 | +17.1 | -5.6 | " | 5.7 | " |
| * Full Throttle height. | |||||||
| Ø A.S.I. and Position Error Corrections are for the A.S.I. connected between pressure and static sides of the Mark VIII head. | |||||||
Table II
Level speed measurments with smooth black finish (D.T.D.308)
| Height in standard atmosphere (feet) | True Air speed (M.P.H.) | A.S.I. Ø m.p.h. | Position error correction m.p.h. | Compressibility correction m.p.h. | R.P.M. (Mean) | Boost lb/sq.in. (Mean) | Supercharger gear |
|---|---|---|---|---|---|---|---|
| 18,000 | 355.5 | 253.5 | +19.8 | -4.8 | 3000 | 8.5 | F.S. |
| 20,000 | 361.5 | 250 | +19.5 | -5.4 | " | 8.5 | " |
| 21,400* | 366 | 247 | +19.2 | -5.8 | " | 8.5 | " |
| 22,000 | 365.5 | 244.5 | +18.9 | -5.8 | " | 8.0 | " |
| 24,000 | 362 | 234.5 | +18.1 | -5.0 | " | 6.6 | " |
| 25,000 | 360 | 229.5 | +17.6 | -5.0 | " | 5.9 | " |
| * Full Throttle height. | |||||||
| Ø A.S.I. and Position Error Corrections are for the A.S.I. connected between pressure and static sides of the Mark VIII head. | |||||||
(2)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito NF. Mk.XV. MP.469
(2 x Merlin 61's)
Short performance and handling trials
SUMMARY
This aircraft has extended wings, a low pressure cabin, four blade metal propellers, four 0.303" Browning guns in an external fairing below the fuselage and is intended for high altitude night fighter work. Short tests to determine its climb and level speed performance were made at the normal load of 17,465 lb. with the centre of gravity at 7.0" aft of datum; an assessment of the principal handling qualities was obtained.
At normal maximum climbing conditions the time to reach the service ceiling of 43,000 ft. is 32½ minutes; it is possible to climb about 800 ft. above this by closing the radiator flaps if care is taken with regard to the engine temperatures. The top speeds are 397 m.p.h. at 16,500 ft. in M.S. gear and 408 m.p.h. at 27,800 in F.S. gear. Owing to unreliable gauges no accurate assessment of the cooling can be obtained but the indications are that the maximum allowable coolant temperature may be exceeded under E.S.M. conditions whilst the oil cooling is satisfactory for T.S.M. conditions.
The handling is satisfactory, there being no tendency for any of the controls to freeze up at height, nor is the extent of icing inside the cabin at all serious; there is no marked difference in behaviour when compared with normal Mosquito aircraft.
(3)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito B. Mk. IV D.K.290/G
(2 Merlin 21's)
Level speed performance and position error trials
with and without stores carried.
SUMMARY
| Condition | Weight (lbs) | Height feet | All-out level power | Max. weak cruising power | ||||
|---|---|---|---|---|---|---|---|---|
| R.P.M. | Boost (lb/sq.in) | T.A.S. (m.p.h.) | R.P.M. | Boost (lb/sq.in) | T.A.S. (m.p.h.) | |||
| Stores IN | 20,000 | 2,000 *11,700 15,000 | 3000 | +12 +12 +8.9 | 321 364 360 | 2650 | +4 | 272 - 323 |
| 18,600 | 2,000 *11,700 15,000 | " | +12 +12 +8.9 | 323 366 362 | " | " | 274 - 325 | |
| Stores OUT | 17,820 | 2,000 *11,700 15,000 | " | +12 +12 +8.9 | 323 366 362 | " | " | 274 - 325 |
| 16,500 | 2,000 *11,700 15,000 | " | +12 +12 +8.9 | 326 369 365 | " | " | 277 - 329 | |
| * Full throttle height under all-out level power conditions. | ||||||||
(4)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito B. Mk. IX. LR.495
(2 Merlin 72's)
Performance trials without external bombs or fuel tanks
SUMMARY
Climb and level speed performance trials have been completed on this aircraft at a take-off weight of 21,910 lb., a loading corresponding to full fuel and oil and four 500 lb. bombs carried internally, but no external bombs or fuel tanks fitted.
The principal results are as follows:
| Max. rate of climb in MS gear (2850 rpm) +12 lb/sq.in. boost | = 2060 ft/min at 14,000 ft. |
| Max. rate of climb in FS gear (2850 rpm) +12 lb/sq.in. boost | = 1310 ft/min. up to 26,700 ft. |
| Service ceiling (FS gear, 3000 rpm) | = 37,000 ft. |
| Absolute ceiling (FS gear, 3000 rpm) | = 37,800 ft. |
| Max. speed in MS gear (3000 rpm, +18 lb/sq.in. boost) | = 393 mph at 13,800 ft. |
| Max. speed in FS gear (3000 rpm, +18 lb/sq.in. boost) | = 405 mph at 25,700 ft. |
(5)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito FB. Mk. VI. HJ.679
(2 Merlin 25's)
Brief Performance trials
SUMMARY
| Climb performance | ||
|---|---|---|
| (i) Loading I (21020 lb.) | Max. rate of climb in M.S. gear | = 1740 ft/min @ 10400 ft. |
| Max. rate of climb in F.S. gear | = 1440 ft/min @ 17000 ft. | |
| Time to reach 20,000 ft. | = 12.85 mins. | |
| Time to reach 25,000 ft. | = 18.8 mins | |
| Estimated service ceiling | = 29800 feet | |
| Estimated absolute ceiling | = 31000 feet | |
| (iii) Loading III (21,985 lb.) | Max. rate of climb in M.S. gear | = 1560 ft/min @ 10400 ft. |
| Max. rate of climb in F.S. gear | = 1300 ft/min @ 17200 ft. | |
| Time to reach 20,000 ft. | = 14.25 mins. | |
| Time to reach 25,000 ft. | = 21.05 mins | |
| Estimated service ceiling | = 29,100 feet | |
| Estimated absolute ceiling | = 30,400 feet | |
| Level speed performance | |||||
|---|---|---|---|---|---|
| Condition | S/C gear | Max. T.A.S. (mph) | Respective full throttle height | ||
| All-out level | Max. cruising | All-out level | Max. cruising | ||
| Loading I (Aux. tanks on) | M.S. | 351 | 321 | 4,700 | 12,200 |
| F.S. | 363 | 332 | 11,900 | 18,600 | |
| Loading II (Aux. tanks off) | F.S. | 368 | 338 | 12,000 | 18,700 |
(6)DeHaviland Aircraft Co. Ltd.
Hatfield Aerodrome
D. H. Mosquito Mk. VI. HJ.679
(2 Merlin 25's)
Tests carried out at Hatfield to check the Maximum Level Speed obtained in previous tests
SUMMARY
Conclusions
Both check tests (Tests 1 and 2) are substantially in agreement with the original Hatfield tests (April 1943) - in point of fact the speed obtained in Test 2 is about 3 m.p.h. faster in F.S. Gear and about the same as the original tests in M.S. Gear, when allowance is made for the fact that external fuel tanks were not fitted on the original tests (April 1943).
It will be seen that about 3 m.p.h. in maximum speed was picked up due to cleaning up the aircraft between Tests 1 and 2.
All these tests show the speed obtained at Hatfield to be about 15 m.p.h. above that obtained at Boscombe Down.
(7)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito IV D.K.290
(2 Merlin 21's)
Comparitive level speeds with ducted saxaphone and multi stub exhausts
SUMMARY
| True air speed (mph) | |||
|---|---|---|---|
| Height | S/c gear | Ducted saxaphone system | Multi stub system |
| 6,000 15,000 18,000 | M.S. M.S. M.S. | 324 358** 351* | 340 373** 369 |
| 16,000 21,600 24,000 | F.S. F.S. F.S. | 346 367** 358 | 360 380* 374 |
* It will be seen from Fig.1 that above 15,000 ft. using MS gear,
i.e. above the full throttle height, the boost pressure with ducted saxaphone was 0.7 lb/sq.in. lower than for the speeds with multi stub exhausts but when
employing FS gear the comparitive difference was only 0.3 lb/sq.in. It is thought
that the larger difference of 0.7 lb/sq.in. encountered was due to a great extent
to a defect in the carburettor possibly in the butterfly mechanism and hence the speeds in MS gear above the full throttle height should not be used for determining the comparitive effect of the exhausts.
** It will be seen that at constant boost the effect on true air speed of fitting the multi stub exhaust system is a gain of 15 mph in MS supercharger gear and 13 mph in FS supercharger.
(8)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito PR Mk XVI DZ 540
(2 Merlin 73's)
Performance, brief handling and pressure cabin tests
SUMMARY
Brief handling and performance trials and tests of the pressure cabin installation have been made on this aircraft, which is the prototype Mosquito PR Mk XVI. The tests were done at the maximum permissible weight of 22340 lb. The principle results are as follows:
| Climb. | Maximum rate of climb in MS gear (2850 RPM, +12 lb/in2 boost) = 1,960 ft/min at 14000 ft. |
| Maximum rate of climb in FS gear (2850 RPM, +12 lb/in2 boost) = 1,150 ft/min up to 26100 ft. | |
| Service ceiling (FS gear, 3000 RPM) = 36000 ft. | |
| Absolute ceiling (FS gear, 3000 RPM) = 36700 | |
| Speed | Maximum all-out level speed in MS gear (3000 RPM, +18 lb/in2 boost) = 385 mph at 13000 ft. |
| Maximum all-out level speed in FS gear (3000 RPM, +18 lb/in2 boost) = 401 mph at 25200 ft. | |
| Maximum crusing speeds. | MS gear (2650 RPM, +7 lb/in2 boost) = 352 mph at 18800 |
| MS gear (2650 RPM, +7 lb/in2 boost) = 366 mph at 30,600 | |
(9)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito F Mk. II. W.4096
(2 Merlin 21's)
Comparitive level speed performance with standard
and tropical engine cowlings
SUMMARY
| (i) Standard cowling: | |
|---|---|
| Max. true airspeed at all-out level power | (a) M.S. s/c = 348 mph at 10,800 ft. |
| Max. true airspeed at all-out level power | (b) F.S. s/c = 358 mph at 17,700 ft. |
| Max. true airspeed at weak mixture cruising power | (a) M.S. s/c = 318 mph at 16,000 ft. |
| Max. true airspeed at weak mixture cruising power | (b) F.S. s/c = 324 mph at 21,700 ft. |
| (ii) Tropical cowling: | |
| Max. true airspeed at all-out level power | (a) M.S. s/c = 336 mph at 9,400 ft. |
| Max. true airspeed at all-out level power | (b) F.S. s/c = 346 mph at 16,000 ft. |
| Max. true airspeed at weak mixture cruising power | (a) M.S. s/c = 310 mph at 15,200 ft. |
| Max. true airspeed at weak mixture cruising power | (b) F.S. s/c = 314 mph at 20,900 ft. |
(10)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito FB. Mk. VI. HX.809
(2 Merlin 25's)
Level speed performance at normal & increased boost rating
SUMMARY
Level speed performance at +18 lb/sq.in. boost and +25 lb/sq.in. boost has been completed on Mosquito FB.Mk.VI, HX.809.
The principal results are as follows:
| MS Gear | |
| Max. speed at +18 lb/sq.in boost | = 353 at 5100 ft. |
| Max. speed at max. full throttle boost (23.9 lb/sq.in.) | = 354 mph at sea level. |
Use of +23.9 lb/sq.in. boost instead of +18 lb/sq.in. at sea level increases the speed by 22 mph.
| FS Gear | |
| Max. speed at +18 lb/sq.in boost | = 363 at 12500 ft. |
| Max. speed at +25 lb/sq.in. | = 369 mph at 7200 ft. |
Use of 25 lb/sq.in. boost instead of +18 lb/sq.in. increases the speed below full throttle height by 23 mph.
Comparison of results @ +18 lb/sq.in. boost with those of Mosquito VI HJ.679, indicate that the speed of that aircraft is of the order of 10-15 mph below average, thus supporting the conclusion made in the 7th part of report No. A. & A.E.E./767,e, that HJ.679 was not fully representative of the type.
(11)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito B. Mk. IX. LR.495
(2 Merlin 72's)
Level speed performance
with two external 500 lbs. bombs fitted
SUMMARY
Level speed tests have been made on this aircraft at the maximum permissible take-off weight of 22,850 lbs., corresponding to the bomber overload condition with external 500 lb. bombs on faired racks under the wings. The tests were made at the normal maximum rating of +18 lb/sq.in. boost and repeated at an increased rating of +21 lb/sq.in.
The principle results are as follows:-
| M.S. gear |
| Maximum level speed (+18 lb/sq.in. boost) 373 mph at 13000 ft. |
| Maximum level speed (+21 lb/sq.in. boost) 375 mph at 10600 ft. |
| Maximum crusing speed (+7 lb/sq.in. boost) 334 mph at 18400 ft. |
| F.S. gear |
| Maximum level speed (+18 lb/sq.in. boost) 383 mph at 25100 ft. |
| Maximum level speed (+21 lb/sq.in. boost) 388 mph at 23000 ft. |
| Maximum crusing speed (+7 lb/sq.in. boost) 345 mph at 30800 ft. |
Use of +21 lb/sq.in boost instead of +18 lb/sq.in. boost increases the top speed below the full throttle heights by 12 mph in M.S. gear and 13 mph in F.S. gear.
The reduction in speed due to fitting the external 500 lb. bombs on faired racks is not known exactly owing to deterioration of the airframe between the two sets of tests but it appears to be of the order of 15-18 mph.
(12)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito B. Mk. XX KB.328
(2 Merlin 31's)
Level speed performance trials
SUMMARY
Level speed performance trials have been completed on this aircraft, a Canadian built version of the B. Mk.IV at a take-off weight of 21430 lb., the loading corresponding to 4-500 lb. bombs in the bomb bay and external fuel tanks beneath the wings.
The principal results are as follow:
| MS gear | |
| Max. all-out speed (+14 lb/sq.in boost) = 354 mph at 7000 ft. | |
| Max. cruising speed (+7 lb/sq.in boost) = 332 mph at 11200 ft. | |
| FS gear | |
| Max. all-out speed (+16 lb/sq.in boost) = 364 mph at 12500 ft. | |
| Max. cruising speed (+7 lb/sq.in boost) = 345 mph at 17700 ft. |
Comparison of the results with those of other Mosquito aircraft fitted with engines of similar power shows that the full throttle heights and performance of KB.328 are rather below average.
(13)Aeroplane and Armament Experimental Establishment
Boscombe Down
Mosquito NF. Mk. 30 MM.748
(2 Merlin 72's)
Position error and level speed performance trials
SUMMARY
Position error trials, and measurement of the level speed performance under combat and cruising power have been made on Mosquito NF Mk.30 MM.748 at a take-off weight of 21,600 lb., with 2 x 50 gallon under-wing tanks fitted.
The position error correction at 20,540 lb. varies non-linearly from +3.5 mph at 150 mph ASI to +8 mph at 180 mph ASI, then linearly to +19.0 mph at 340 mph ASI.
The maximum true level speeds are:
M.S. Supercharger gear.
| M.S. Supercharger gear. | |
|---|---|
| Max. cruising power. | Combat power |
| 340 mph at 17,000 ft. | 371 mph at 12,200 ft. |
| F.S. Supercharger gear. | |
| Max. cruising power. | Combat power |
| 364 mph at 27,500 ft. | 397 mph at 24,800 ft. |
The performance generally is up to the expected standard for this varient of the Mosquito.
Supplemental
Miscellaneous
Lewis Brandon of 157 squadron commented in his book:
"We were told that we would be kept on operation Diver for a while. Swift modifications were carried out to all the Mozzies. The exhaust shrouds were dispensed with, extra boost was given to the engines, we were supplied with 150 octane petrol and, of course, the noses were strengthened. With the exception of the exhaust shrouds, all these modifications were retained when we returned to our bomber support role."Lewis Brandon, DSO DFC*, Night Flyer, p 156. ISBN 0 907579 77 9, 1961, (Republished 1999 by Crecy Publishing)