Pursuit Single Engine P-51B-1-NA AAF No. 43-12093
SUBJECT: Preliminary high speed and climb performance tests
BRANCH: Flight SERIAL No. FS-M-19-1587-A A. Purpose 1. To report results of high speed and climb performance tests conducted at the manufacturer's factory on the P-51B-1-NA airplane, AAF No. 43-12093. B. Factual data. 1. Airplane was tested at a take-off gross weight of 8430 pounds, and was equipped as a standard production fighter with four .50 caliber guns with the gun openings taped but shell ejection chutes open, three antenna wires and a short radio mast aft of the cockpit. Finish was filled and sanded and was supposed to be the standard production finish. Airplane equipped with the Packpard Merlin V-1650-3 engine with 11.5 inch and 10.1 inch diameter blowers, and with a four-bladed Hamilton Standard propeller, blade design No. V-6487A-24. Power data obtained from Packard power curve P-18, No. 5 dated Nov. 21, 1942 for the V-1650-3 engine with 11.5 inch and 10.1 inch blowers. 2. High speeds obtained with the oil cooler flap and coolant flap set for automatic opertation since there were no provisions on this airplane for selective operation and no time was available for a test installation of a selective control. |
True Airspeed M.P.H. | R.P.M. | Man. Press. " Hg. | BHP From Power Chart | Altitude Ft. | Coolant Flap Position Inches open From Flush | Oil Flap Position Inches open From Flush |
(a) Low blower Operation | ||||||
363 | 3,000 | 60.5 | 1,450 | 5,000 | 6.0 | W.O (5) |
394 | 3,000 | 60.5 | 1,485 | 10,000 | 5.0 | 3.5 |
425 | 3,000 | 60.5 | 1,530 | 16,800 | 1.5 | 1.0 |
422 | 3,000 | 49.0 | 1,270 | 23,200 | 1.0 | Flush |
(b) High blower Operation | ||||||
422 | 3,000 | 60.5 | 1,270 | 23,200 | 1.0 | .5 |
441 | 3,000 | 60.5 | 1,275 | 29,800 | 1.0 | Flush |
421 | 3,000 | 48.0 | 985 | 35,000 | .5 | Flush |
403 | 3,000 | 40.7 | 815 | 38,000 | .5 | Flush |
Opening coolant flap wide open from flush position slowed the airplane from 349 M.P.H. I.A.S. to 325 M.P.H. at 18,000 Ft.; opening the oil cooler flap decreased the speed an additional 10 M.P.H. I.A.S.
3. Climb Data, 3,000 R.P.M., Oil and Coolant flaps Wide Open. |
Altitude Ft. | Man. Press. " Hg. | Rate of Climb Ft/min. | BHP from Chart |
(a) Low blower Operation | |||
S.L. | 60.5 | 3,600 | 1,500 |
5,000 | 60.5 | 3,570 | 1,510 |
10,000 | 60.5 | 3,540 | 1,525 |
13,000 | 60.5 | 3,520 | 1,510 |
17,400 | 52.3 | 2,965 | 1,320 |
(b) High blower Operation | |||
17,400 | 60.5 | 2,965 | 1,320 |
20,000 | 60.5 | 2,915 | 1,310 |
26,000 | 60.5 | 2,780 | 1,260 |
30,000 | 51.6 | 2,125 | 1,075 |
35,000 | 41.8 | 1,280 | 850 |
40,000 | 32.8 | 450 | 630 |
S/C 42,000 | 29.1 | 100 | 540 |
A/C 42,600 | 28.2 | 0 | 515 |
See also Official Army Performance Tests on P-51B Airplane, May 15, 1943
Pursuit Single Engine P-51B-1-NA AAF No. 43-12093
SUBJECT: Time to Climb
BRANCH: Flight SERIAL No. FS-M-19-1587-A (Addendum #1) A. Purpose 1. To report time to climb as calculated from data given in Memorandum Report, Serial No. FS-M-19-1587-A. B. Factual Data 1. Time to Climb; 3,000 r.p.m., oil and coolant flaps wide open. |
Altitude Ft. | Man. Press. " Hg. | Rate of Climb Ft/min. | BHP from Chart | Time to Climb Min. |
(a) Low blower Operation | ||||
S.L. | 60.5 | 3,600 | 1,500 | 0 |
5,000 | 60.5 | 3,570 | 1,510 | 1.4 |
10,000 | 60.5 | 3,540 | 1,525 | 2.8 |
13,000 | 60.5 | 3,520 | 1,510 | 3.7 |
17,400 | 52.3 | 2,965 | 1,320 | 5.05 |
(b) High blower Operation | ||||
17,400 | 60.5 | 2,965 | 1,320 | 5.1 |
20,000 | 60.5 | 2,915 | 1,310 | 5.9 |
26,000 | 60.5 | 2,780 | 1,260 | 7.7 |
30,000 | 51.6 | 2,125 | 1,075 | 9.8 |
35,000 | 41.8 | 1,280 | 850 | 12.3 |
40,000 | 32.8 | 450 | 630 | 18.6 |
S/C 42,000 | 29.1 | 100 | 540 | 26.3 |
A/C 42,600 | 28.2 | 0 | 515 | -- |
Memorandum Report on Pursuit Single Engine P-51B-1-NA AAF No. 43-12093, Time to Climb
Flight Tests on the North American
P-51B-5-NA Airplane, AAF No. 43-6883
The P-51B is a single engine, low wing, long range fighter.
Its long range makes it ideal for escort purposes, and its performance as a fighter aircraft is better or at least equal to that of any enemy fighter that might be encountered.
The rate of climb is good and the high speed in level flight is exceptionally good at all altitudes, from sea level to 40,000 feet.
The airplane is very maneuverable with good controllability at indicated speeds to 400 MPH. The stability about all axes is good and the rate of roll is excellent, however, the radius of turn is fairly large for a fighter. The cockpit layout is excellent, but visibility is poor on the ground and only fair in level flight. High speed and climb performances have been completed on this airplane at a take-off weight of 9205 lbs. This loading corresponds to the average P-51B combat weight with full oil, 180 gallons of fuel and specified armament and ammunition. The principal results are as follows: |
Maximum speed at critical altitudes. (67" Hg. man. pressure & 3000 RPM) |
Low Blower at 16,600 feet | 430.0 MPH |
High Blower at 29,400 feet | 442.0 MPH |
Maximum speed at sea level (67" Hg. manifold pressure & 3000 RPM) |
371.0 MPH |
Rate of climb at critical altitudes. (67" Hg. man. pressure & 3000 RPM) |
Low Blower at 13,800 feet | 3450 ft/min. |
High Blower at 25,500 feet | 2660 ft/min. |
Time to climb to high blower critical altitude, 25,500 feet. |
(67" Hg. pressure and 3000 RPM) | 8.28 min. |
Service ceiling | 42,000 ft. |
Preliminary Results of Performance Tests on
a P-51B Airplane with 44-1 Fuel
P-51B-5-NA, V-1650-7 Engine
Blower Setting | M.A.P. | Altitude | Climb ft/min. |
Low | 61" | 9000 | 3830 - 3950 |
Low | 67" | 6500 | 4300 - 4370 |
Low | 75" | 3500 | 4650 - 4670 |
High | 61" | 22000 | 3030 - 3060 |
High | 67" | 19000 | 3440 - 3480 |
High | 75" | 17800 | 3650 - 3680 (Flight 32) |
16000 | 3740 - 3790 (Flight 33) |
Climb data corrected to normal gross weight of 8,460 lbs. |
Blower Setting | M.A.P. | Altitude | TAS corrected to standard conditions |
Low | 61" | 15200 | (418) |
Low | 67" | 12100 | (420) |
Low | 75" | 7800 | 419 - 423 |
High | 61" | 26600 | (436) |
High | 67" | 24200 | (441) |
High | 75" | 21200 | 445 |
Values in parenthesis estimated from previous tests. |
P-51B-15-NA 43-24777
(Packard Merlin V-1650-7)
Performance Tests on P-38J, P-47D and P-51B Airplanes
Tested with 44-1 Fuel. (GRADE 104/150)
1. Flight tests were started on P-38J, P-47D, and P-51B airplanes at Wright Field on approximately 20 March 1944 in order to measure the performance and note any effect on flight characteristics when flown with 44-1 fuel.
Tests on the P-51B have been completed but tests on the P-38J and P-47D have not been completed to date.
2. All tests were flown with the airplanes loaded to their maximum combat gross weight. The P-38J airplane tested was P-38J-15, AAF No. 43-28392, equipped with Allison V-1710-89 and 91 engines with Curtiss electric three blade propellers. Gross weight at take-off was 17,360 lbs. with the c.g. at 26.72%. The P-47D tested was AAF No. 42-26167 and was equipped with Pratt & Whitney R-2800-63 engine and an A-23 turbo regulator. Gross weight at take-off was 13,320 lbs. with the c.g. at 29.5%, gear up. The P-51B tested was the P-51B-15, AAF No. 43-24777 and was equipped with a Packard V-1650-7 engine with a 11 ft. 2 in., four blade constant speed propeller. Gross weight at take-off was approximately 9680 lbs. The weight included 265 gal. of fuel, full oil, and no ammunition (85 gal. in auxiliary tank instead of ballast for ammunition). 3. There was no noticeable change in handling characteristics of any of the airplanes tested when operating at the higher powers which were obtainable with the 44-1 fuel. Only a slight increase in vibration was noted at the higher powers. On one long range test made with the P-51B, there was no apparent trouble due to the 44-1 fuel. 4. All performance data obtained on the P-51B is included in the attached curves. It will be noted that all tests were run with the wing racks installed. Speeds would be approximately 12 mph faster with the wing racks removed as shown by the dash line curve on the Speed vs Altitude Curve. Approximately 16 MPH increases in speed below critical altitude and approximately 600 ft. per minute increase in rate of climb below critical altitude was obtained by using the 75 Hg. Manifold pressure allowed by 44-1 fuel. No tests were made on this airplane with standard fuel. |
With Wing Racks | Without Wing Racks | ||
67" Hg., 3000 RPM | 75" Hg., 3000 RPM | 75" Hg., 3000 RPM | |
Max. speed at Sea Level | 364 mph | 380 mph | 388 mph |
Max. speed in MS gear | 408 mph at 10400 ft. | 411 mph at 7400 ft. | 422 mph at 7400 ft. |
Max. speed in FS gear | 426 mph at 23900 ft. | 431 mph at 20600 ft. | 444 mph at 20600 ft. |
67" Hg., 3000 RPM | 75" Hg., 3000 RPM | ||
Max. speed in MS gear | 3,920 ft/min at 5,600 ft. | 4,380 ft/min at 2,300 ft. | |
Max. speed in FS gear | 3,170 ft/min at 19,200 ft. | 3,700 ft/min at 15,700 ft. |
Flight Tests on the North American
P-51B-15 Airplane, AAF No. 43-24777
Using 44-1 Fuel
The P-51B-15 airplane, AAF No. 43-24777 is a low wing fighter equipped with a Packard V-1650-7 engine.
Equipped with an additional fuselage tank and wing racks to which may be attached fuel tanks the airplane has long range for a fighter.
The airplane is very maneuverable with excellent controllability at all speeds up to slightly over 400 MPH indicated, the highest speeds attained in level flight. Stability is good about all axes, and recovery from stalls is normal. The airplane has a fairly short radius of turn and an excellent rate of roll. Visability is poor in taxing and only fair in level flight. The cockpit layout in general is good. All tests were made at a gross weight at takeoff of 9335 lbs. which included full oil and 265 gallon of fuel. Level flight and climb performance were completed with wing racks. In addition level flight speeds were obtained at the critical heights without wing racks. In level flight the high blower critical altitude for 75 in. Hg. manifold pressure and 3000 RPM was 20,800 ft. At this altitude the airplane attained a maximum true speed of 444.0 MPH at 75 in. HG. manifold pressure without wing racks, a high speed of 431 MPH at 75 in. Hg. manifold pressure with wing racks, and a high speed of 417 MPH at 67 in. Hg. manifold pressure with wing racks. At 24,000 ft., high blower critical altitude for 67 In. Hg. manifold pressure and 3000 RPM, a maximum true speed of 426 MPH was attained. In climb the low blower critical altitude for 75 in. HG. manifold presure and 3000 RPM was 2,200 ft. At this altitude the airplane attained a maximum rate of climb of 4380 ft/min. at 75 in. Hg. manifold pressure and 3,820 ft/min. at 67 in. Hg. manifold pressure. The service ceiling of the airplane was 40,500 ft. and the absolute ceiling was 41,200 ft. High speed in level flight at 3000 RPM, mixture auto rich, and oil and coolant shutters in automatic. |
Present War Emer. Power | Proposed War Emer. Power | ||||||
Altitude Ft. | Blower | Man. Press. | Std. BHP | True Speed | Man. Press. | Std. BHP | True Speed |
0 | Low | 67.0 | 1580 | 361.5 | 75.0 | 1788 | 376.5 |
4000 | Low | 67.0 | 1622 | 380.0 | 75.0 | 1830 | 376.5 |
*7400 | Low | 67.0 | 1660 | 395.5 | 75.0 | 1868 | 395.5 |
**10300 | Low | 67.0 | 1695 | 409.0 | |||
17000 | Low | 52.8 | 1350 | 398.0 | |||
24000 | Low | 39.8 | 1037 | 385.0 | |||
18000 | High | 67.0 | 1390 | 408.0 | 75.0 | 1577 | 423.0 |
*20800 | High | 67.0 | 1390 | 417.0 | 75.0 | 1572 | 431.0 |
**24000 | High | 67.0 | 1390 | 426.0 | |||
28000 | High | 57.3 | 1200 | 419.0 | |||
32000 | High | 48.4 | 1038 | 410.0 | |||
28000 | High | 36.4 | 822 | 390.0 |
Also see: P-51B High Speed Performance Engineering Division's charting of North Amerian Flight Test Data.
P-51B-15
43-24755, 43-24757, 43-24775
(Packard Merlin V-1650-7)
Service Test of Nominal 104/150 Grade Fuel
Performance gains. - Attempts were made throughout the test to determine the average gain in performance due to the increased power rating allowed by the special fuel.
Speed runs and climbs were made by approximately twenty-five pilots of all grades of experience.
Speed curves shown in Inclosure 3 are average curves drawn from all data obtained from all three airplanes of each type.
Data are not reduced to standard conditions, but are plotted against pressure altitude from actual free air temperatures.
All flights were made with full military load.
P-51-B-15 Airplane. Increase of power from the standard war emergency rating of sixty-seven inches Hg. to the test rating of seventy-five inches Hg. resulted in an average true air speed increase of fifteen m.p.h. from sea level to the seventy-five inches Hg. low blower critical altitude (about 8000 feet). Speed increase was also approximately fifteen m.p.h. from fourteen thousand feet to the high blower seventy-five inches for critical of about twenty-one thousand feet. No measurable difference was found between airplanes. The aneroid controlling supercharger shifting point was reset at the begining of the test to shift from low to high blower at sixty-two inches Hg. in a war emergency climb. This change resulted in a blower shift altitude of approximately seventy-five hundred feet, so that it was necessary to select low blower manually for cruise at medium altitudes where the desired power was available in low blower. |
Flight Tests on the North American
P-51D Airplane, AAF No. 44-15342
Fuel consumption and speed data listed in the flight operation instruction chart have been spot checked by duplicating in the test program some of the power settings shown in the T. O.
By comparing the results obtained with the T. O. figures, a quick estimate of the validity of the T. O. may be made.
High speed and climb performance have been obtained on this airplane at a take-off gross weight of 9760 pounds. Performance was obtained up to an altitude of 35,000 feet in increments of 5000 feet in a clean configuration. The clean configuration included one external bomb rack on each wing. Additional configurations were flown at 5000 and 15,000 feet including two 110 gallon tanks, two 500 pound bombs, and two 250 pound bombs. The principal results are as follows: A. Clean Configuration (with bomb racks). |
1. | Maximum speed at critical altitudes | ||
High Blower | |||
War Emergency power (3000 RPM and 67") 26000' | 442 MPH | ||
Military power (3000 RPM and 61") 28000' | 439 MPH | ||
Normal Rated power (2700 RPM and 46") 29400' | 420 MPH | ||
Low Blower | |||
War Emergency power (3000 RPM and 67") 10000' | 417 MPH | ||
Military power (3000 RPM and 61") 13200' | 413 MPH | ||
Normal Rated power (2700 RPM and 46") 16200' | 387 MPH | ||
2. | Maximum speed at sea level | ||
War Emergency power (3000 RPM and 67") | 375 MPH | ||
Military power (3000 RPM and 61") | 364 MPH | ||
Normal Rated power (2700 RPM and 46") | 323 MPH | ||
3. | Rate of climb at critical altitude. | ||
War Emergency power (3000 RPM and 67") high blower (19,000') | 3200 ft/min. | ||
War Emergency power (3000 RPM and 67") low blower (4,800') | 3600 ft/min. | ||
4. | Time to climb to service ceiling, war emergency power 3000 RPM and 67") (41600') | 28 minutes. |
B. True speed loss, MPH from clean configuration due to external load items (2700 RPM and 46"). |
2-110 Gal. Tanks | 2-500 Lb. Bombs | 2-250 Lb. Bombs |
5000 ft. 45 | 36 | 25 |
25000 ft. 47 | 33 | 23 |
Performance Calculations for Model P-51D Airplane
(N.A.A. Model No. NA-122)
Summary
Maximum Speed War Emergency Power
(3000 RPM. 67" Hg. M.P.) | ||
At Sea Level | 368 MPH | |
At Low Blower A.C.A.* | 414 MPH/11,300 ft. | |
At High Blower A.C.A.* | 440 MPH/24,500 ft. | |
Maximum Rate of Climb War Emergency Power
(3000 RPM 67" Hg. M.P.) | ||
At Sea Level | 3410 ft./min. | |
At Low Blower A.C.A.* | 3510 ft./min./7500 ft. | |
At High Blower A.C.A.* | 2680 ft./min./21,200 ft. | |
Time to Climb to 20,000 ft. at War Emergency Power |   6.4 min. |
Performance Calculations for P-51H Airplane
(N.A.A. Model No. NA-126)
Maximum Speed Combat Rating
(3000 R.P.M. 90 Hg. M.P. W.I.) | ||
In High Blower at A.C.A.* | 471 m.p.h./22,700 ft. | |
In Low Blower at A.C.A.* | 449 m.p.h./9000 ft. | |
In Low Blower at Sea Level | 413 m.p.h. | |
Maximum Rate of Climb Combat Rating
(3000 R.P.M. 90 Hg. M.P. W.I.) | ||
In Low Blower at Sea Level | 5120 ft./min. | |
In Low Blower at A.C.A.* | 5210 ft./min/4600 ft. | |
In High Blower at A.C.A.* | 3970 ft./min/18,300 ft. | |
Time to Climb to 20,000 ft. with Combat Power (90) Hg. M.P. |   4.58 min. |
Also see: | P-51H Altitude Performance |
Brake Horsepower vs Altitude V-1650-9 |
Flight Tests on the North American
P-51H Airplane, AAF No. 44-64161
A. Maximum speed at critical altitudes |
High blower | (67.0" and 3000 RPM) 30750' | 450.0 MPH |
(61.0" and 3000 RPM) 32550' | 444.5 MPH | |
Low blower | (67.0" and 3000 RPM) 16400' | 435.0 MPH |
(61.0" and 3000 RPM) 19300' | 432.5 MPH |
B. Maximum speed at sea level |
(67.0 and 3000 RPM) | 358.0 MPH | |
(61.0 and 3000 RPM) | 351.0 MPH |
C. Rate of Climb |
1. Sea Level | (67.0 and 3000 RPM) | 3200 ft/min. |
(61.0 and 3000 RPM) | 2875 ft/min. | |
2. Low blower critical altitudes | ||
(67.0 and 3000 RPM) | 3395 ft/min. | |
(61.0 and 3000 RPM) | 3080 ft/min. | |
3. High blower critical altitudes | ||
(67.0 and 3000 RPM) | 2640 ft/min. | |
(61.0 and 3000 RPM) | 2360 ft/min. | |
4. Time to climb to service ceiling | ||
(67.0 and 3000 RPM) | 23.7 min. | |
(61.0 and 3000 RPM) | 24.6 min. |
Flight Test of the P-51H Airplane, AAF No. 44-64182
Summary
All tests at the fighter configuration (bomb and rocket racks only) were flown at a take-off weight of 9544 lbs.
Data at war emergency rating with water injection at 3000 rpm.
|
Altitude Ft. | True Air Speed MPH | MP "Hg. | Blower | Throttle Setting |
S.L. | 401 | 90 | Low | Part |
*6800 | 431 | 90 | Low | W. O. |
**13400 | 423 | 90 | High | Part |
***21200 | 451 | 90 | High | W. O. |
25000 | 448 | 78 | High | W. O. |
* | Low Blower Critical Altitude for 90" Hg., MP |
** | Altitude for Blower Shift. |
*** | High Blower Critical Altitude for 90" Hg., MP. |
Climb data for war emergency power rating (3000 rpm with water injection). |
Alitude Ft. | True Air Speed | Rate of Climb Min. | Time of Climb Min. | MP "Hg. | Blower | Throttle Setting |
S.L. | 175 | 4680 | .0 | 90 | Low | Part |
2200 | 181 | 4680 | 0.5 | 90 | Low | W. O. |
9600 | 202 | 3660 | 2.2 | 90 | High | Part |
16000 | 224 | 3680 | 4.0 | 90 | High | W. O. |
30000 | 283 | 1720 | 9.4 | 53.5 | High | W. O. |
Also see: | |
P-51H Speed Clean | |
P-51H Speed with Racks | |
P-51H Climb |
Improved Performance Low Altitude Figher Aircraft.
'Mustang' AL.963 with Merlin 65 (Special).
General Conclusion:-
Preliminary flight performance data obtained on a Merlin 65 engine re-rated to +23 lb. boost prior to tests on R.M. 14 S.M. engine. This engine was fitted with an S.U. injection pump to give the increased fuel flow requirments necessitated by the higher boost. |
(1) | Level speeds. An increase of 17 M.P.H. is obtained from G.L. up to 7,000 ft. and from 15,000 ft. to 19,000 ft. |
  | |
(2) | Climb. Rate of climb improved by 900 ft/min. from G.L. up to 4,000 ft. and 960 ft/min. from 13,000 ft. up to 15,000 ft. |
Mustang III FX.858
(Merlin 100)
Brief performance trials and position error measurement
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. |
Mustang III FX.953
(Packard Merlin V.1650-3)
Position error, climb and level speed performance trials
Position error and performance trials have been completed on this aircraft at a take-off weight of 9200 lb. without external bombs or fuel fitted.
The principal results are as follows :- 1. Climb |
(a) | Normal rating (2700 rpm., 46 in. manifold pressure) | |
Max. rate of climb in MS gear | = 2060 ft/min at 16700 ft. | |
Max. rate of climb in FS gear | = 1555 ft/min at 30200 ft. | |
Service ceiling | = 40700 ft. | |
Absolute ceiling | = 41300 ft. |
(b) | Combat rating (3000 rpm., 67 in. manifold pressure) | |
Max. rate of climb in MS gear | = 3610 ft/min at 10600 ft. | |
Max. rate of climb in FS gear | = 2690 ft/min at 23400 ft. | |
Service ceiling | = 42800 ft. | |
Absolute ceiling | = 43600 ft. |
2. Level speed |
(a) | Max. cruising (2700 rpm., 46 in. Hg. manifold pressure) | |
Max. speed in MS gear | = 406 mph at 20600 ft. | |
Max speed in FS gear | = 438 mph at 33000 ft. (approximately) |
(b) | All out level (3000 rpm., 67 in. Hg. manifold pressure) | |
Max. speed in MS gear | = 424 mph at 15500 ft. | |
Max. speed in FS gear | = 450 mph at 28000 ft. |
Mustang IV T.K.589
(Packard Merlin V.1650-7)
Position error of static vent and
brief level speed trials
Conclusions.
The maximum true airpseed of this aircraft, using 3,000 RPM in M.S. gear was 396 mph at 10,300 feet, with +18 lb/sq.in. boost, and 398 at 4,300 ft. with +25 lb/sq.in. boost. Use of +25 lb/sq.in. instead of +18 lb/sq.in. boost increased the True Air Speed below full throttle height 25 mph. |
Height ft. | T.A.S. m.p.h. | A.S.I. m.p.h | P.E.C. | C.E.C. | Boost lb/sq.in. |
0 | 379 | 374 | +5.25 | -.25 | +25.0 |
2,000 | 388 | 372 | +5.25 | -1 | +25.0 |
*4,300 | 398 | 370 | +5.25 | -2 | +25.0 |
6,000 | 398 | 362 | +5 | -2.75 | +23.0 |
8,000 | 398 | 351 | +5 | -3.25 | +20.6 |
10,000 | 397 | 340 | +4.75 | -3.75 | +18.3 |
12,000 | 395 | 329 | +4.75 | -4.25 | +15.9 |
0 | 354 | 349 | +5 | 0 | +18.0 |
2,000 | 362 | 347 | +5 | -.75 | " |
4,000 | 370 | 345 | +4.75 | -1.5 | " |
6,000 | 379 | 344 | +4.75 | -2.25 | " |
8,000 | 387 | 342 | +4.75 | -3 | " |
*10,300 | 396 | 338 | +4.75 | -3.75 | " |
Combat Conditions |
3000 r.p.m. + 25 lbs/sq.in. B.H.P. at S.L. = 1940 |
Max. power in "M.S." gear = 1940 B.H.P. at S.L. |
Max. power in "F.S." gear = 1810 B.H.P. at 12,000 ft. |
Supercharger change height = 5,000 ft. |
3000 r.p.m. at 67" Hg. boost pressure. B.H.P. at S.L. = 1630 |
Max. power in "M.S." gear = 1,700 B.H.P. at 5,750 ft. |
Max. power in "F.S." gear = 1,555 B.H.P. at 17,750 ft. |
Supercharger change height = 10,500 ft. |
3000 r.p.m. + 61" Hg. boost pressure. B.H.P. at S.L. = 1490 |
Max. power in "M.S." gear = 1580 B.H.P. at 8,500 ft. |
Max. power in "F.S." gear = 1400 B.H.P. at 21,000 ft. |
Supercharger change height = 13,400 ft. |
Climb and cruise |
2,700 r.p.m. + 46" Hg. boost pressure. B.H.P. at S.L. = 1050 |
Max. power in "M.S." gear = 1150 B.H.P. at 11,250 ft. |
Max. power in "F.S." gear = 1080 B.H.P. at 22,000 ft. |
Supercharger change height = 14,250 ft. |
Weak mixture cruise |
2,400 r.p.m. + 36" Hg. boost pressure. B.H.P. at S.L. = 730 |
Max. power in "M.S." gear = 820 B.H.P. at 13,000 ft. |
Max. power in "F.S." gear = 755 B.H.P. at 22,500 ft. |
Supercharger change height = 16,250 ft. |
The Merlin engined P-51 went operational 1 December 1943 with the 354th Fighter Group based in Boxted UK.
By D-Day, seven 8th Air Force Groups would join them as well as seven RAF Squadrons.
In the MTO, the 31st and 52nd Fighter Groups exchanged their Spitfires for Mustangs in spring 1944.
The P-51B that equipped these units was delivered with the Packard Merlin V-1650-3 until April 1944, when replacement aircraft began to be delivered with the V-1650-7 engine featuring maximum power peaking at lower altitudes.
The P-51 operated on 100/130 grade fuel with War Emergency Power limited to 67" up to June 1944.
On 29 March 1944 the Commanding General, Army Air Forces authorized the procurement of the necessary parts to modify all P-38, P-47 and P-51 airplanes in the United Kingdom for the use of Grade 150 fuel, subject to the relevant engines being cleared to use the fuel. 1 2 During March & April 1944 flight tests were conducted at Wright Field on the P-51B-15 airplane, AAF No. 43-24777, using 44-1 fuel, at the request of the Power Plant Laboratory, Engineering Division. 3 These tests were made to determine the performance of the airplane at the higher powers allowable with 44-1 fuel as compared with the performance at powers allowable for standard aviation fuel. Parallel tests were conducted by Proving Ground Command at Eglin Field, Florida on P-51B airplanes, AAF Nos. 43-24755, 43-24757, and 43-24775. The Power Plant Laboratory concluded in a 19 April 1944 memorandum report that the "Packard built Rolls-Royce V-1650-7 engine will satisfactorily comply with a 75 In. Hg manifold pressure war emergency rating with Grade 44-1 fuel". 4 As a result of the engine clearance and airplane trials the P-51-B airplane was cleared for operation at 75" Hg by late April. 5 The modifications required to the P-51 to use the 150 grade fuel were: modify manifold pressure regulator, modify supercharger volute drain valve, install new type induction center manifold extension gland seals, use of Lodge RS5/5 or KLG RC5/3 spark plugs, installation of bulged exhaust stacks, and reset supercharger aneroid switch. 6 By June 1944, final release on Project P.P.F. had been made approving 75" manifold pressure for the P-51 (both the 1650-3 and 1650-7 engines), as well as increased powers for the P-38 and P-47. 7 Deliveries of Grade 100/150 aviation fuel to Eighth Air Force fighter airfields commenced in June 1944. 8 9 10 This coincidentally occured about the same time as the introduction of the P-51D into service. Even though the USAAF had cleared the P-51 for 75" Hg., the Eighth Air Force chose 72" Hg as the P-51's War Emergency Rating. 11 12 Apparently there is more to the story, however, as Encounter Reports demonstrate that 75" Hg was used operationally. 13 14 By January 1945, fourteen of the Eighth Air Force's fifteen Fighter Groups were operating Mustangs, the sole holdout being the 56th FG in P-47's. Maintenance difficulties with spark plug fouling led to the decision to convert all fighter groups to 100/150 grade fuel reformulated with increased levels of ethylene dibromide (1.5T). Deliveries of PEP, as the new 100/150 blend was called, began to be issued to all fighter groups in February 1945. The use of PEP, however, cooroded the valve seats of the V-1650 at an unacceptable level. Consequently, the standard 100/150 (1T) grade fuel was reverted to by the end of March 1945. 15 16 The Eighth Air Force also had hoped to supply the 352nd and 361st Fighter Groups based on the continent with 100/150 grade fuel. This was deemed impractical from a logistical viewpoint, although admittedly such difficulties did not prevent the RAF's 2nd TAF from being supplied with 100/150 grade fuel. 17 Technical Operations, Eighth Air Force issued a 4 April 1945 Memorandum in which 100/150 grade fuel experience in the Eighth Air Force was summarized. It is reproduced in full below: 1. The following is a summary of 100/150 grade fuel experience in Eighth Air Force. |
Those RAF Mustang units tasked with defending against the V-1 were modified to operated at +25 lbs./sq.in. - the equivalent of 80" Hg. 21 22 On 24 August 1944, by which time the V-1 threat had subsided, the Ministry of Aircraft Production directed Rolls Royce: "all Packard Merlin V.1650-7 engines to be modified to operate at 25 lbs. boost". 23 Raising the WER rating from 67" Hg to 80" Hg increased Sea Level speed by 30 mph. 24 On 18 September 1944 ADGB noted, that with respect to the Mustang III/Packard Merlin 1650-7, "A total of over 7,000 hours have been flown at a maximum boost pressure of + 25 lbs./sq. in.". 25 The RAF's Mustang Pilot's Notes gives the Combat Engine Limitation as "81 ins. boost for 5 minutes when using 150 grade fuel". 26 Combat Reports and Squadron Operations Record Books show 150 Grade fuel and +25 lbs boost was used operationally over the continent by UK based Mustangs of ADGB. 27 28 |
1st Lt. Raymond R. Flowers, 1 November 1944, 20th FG | I closed steadily pulling over 70 inches. |
1st Lt. James F. Hinchey, 14 November 1944, 353rd FG | For fifteen minutes at 74 hg and indicating 600 mph |
2nd Lt. Thomas R. Drybrough, 27 November 1944, 353rd FG | "I had been pulling over 70" H.G. and was indicating about 425 MPH at approximately 14,000 feet." |
1st Lt. Charles E. Yeager, 13 September 1944, 357th FG | I rolled over and was pulling around 70Hg. |
Capt. Charles E. Yeager, 6 November 1944, 357th FG | I got behind him and was pulling 75 Hg. |
Lt. Col. Roy A. Webb, 25 June 1944, 361st FG | I closed very slowly and pulled as much as 70 inches of mercury. |
1st Lt. Thomas H. Hall, 15 August 1944, 364th FG | I put on 70 inches and gradually pulled up on them. |
Lt. Col. Kyle L. Riddle, 24 December 1944, 479th FG | "I pulled about 70" to 75" mercury..." |
F/Lt Pearson, 5 April 45, 65 Squadron | "Opening up to 70 inches I overtook him..." |
F/Lt. G. M. Davis, 23 March 1945, 129 Squadron | "Opened up to +25 lbs of boost 3,000 revs and dived down to engage." |
Encounter Reports of P-51 Mustang Pilots
By Brent Erickson, Neil Stirling, and Mike Williams
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