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imp. gall

P-51 variants

and The North American Aviation P-51 Mustang was an American long-range single-seat fighter aircraft that entered service with Allied air forces in the middle years of World War II.



This article is a guide to some of the basic dimensional data, performance characteristics and armament of the P-51 series, using representative figures gathered from reliable sources.

P-51 Mustang Dimensions, performance and armament

The basic dimensions of the P-51/A-36 variants remained consistent from the XP-51 through to the experimental "lightweight" P-51s, although there were relatively minor variations in height and wing areas. The P-51H was the first production version of the Mustang to feature a lengthened fuselage and taller tailfin.

Power ratings

The power rating for the engines could vary according to the type of supercharger fitted, the size of the compressor impeller(s) and the gear speeds selected.

In the case of the Packard Merlin V-1650s, used from the P-51B on, two sets of power ratings can be quoted because these engines were fitted with two-stage, two-speed superchargers; the maximum power generated by the V-1650-3 was 1,490 hp (1,111 kW) at 13,750 ft (critical altitude) (4,191 m) in low blower using of Mercury "boost"; i.e. 61" Hg. The "boost" is the pressure to which the air–fuel mixture is compressed before being fed through to the engine's cylinders (manifold pressure). Because air pressure and air density decrease with altitude the efficiency of a piston engine drops because of the reduction in the amount of air that can be drawn into the engine; for example the air density at is 1/3 of that at sea level, thus only 1/3 of the amount of air can be drawn into the cylinder and only 1/3 of the fuel can be burnt.

In the case of the Mustang the air being forced through the supercharger air intake was first compressed by the supercharger's first stage, or low blower. A Bendix-Stromberg pressure carburettor injected fuel at 5 psi through a nozzle direct into the supercharger and the compressed air/fuel mixture was then directed to the cylinders. An intercooler was provided to stop the compressed mixture from becoming too hot and either igniting before reaching the cylinders, or creating a condition known as knocking.

Once the aircraft reached and climbed through the critical altitude the power would start to drop as the atmospheric pressure dropped; a second stage compressor was needed to allow the engine to continue to perform at higher altitudes. When the aircraft reached a certain altitude (20,000 ft (6,096 m) for the -3) the second stage, or high blower of the supercharger was started; the air/fuel mixture coming through the low blower then flowed through the second stage to be compressed again. This second stage blower required approximately 200 hp (149 kW) to drive it. As a result the maximum power generated by the V-1650-3 in high blower was 1,210 hp (902 kW) at 25,800 ft (7,863 m), using 61" Hg.

The V-1650-7 used in later P-51B/Cs and in the P-51D/K produced slightly more power but, because of the use of slightly different gear ratios for the impellers, the critical altitude ratings of the supercharger stages were lower, 8,500 ft (2,590 m) and 21,400 ft (6,523 m) respectively. Experience showed that most air-to-air combat over Europe was taking place between these altitudes.

The power of the engine could also change according to the Octane rating of the aviation fuel being used. Higher octane fuels allowed boost pressures to be increased without the risks of pre-ignition or knocking.

The British and Australian air forces measured boost pressure using the formula of lbs/sq.inch (or psi). The normal atmospheric pressure at sea level is 14.5 psi, so a reading of +6 means that the air/fuel mix is being compressed by a supercharger blower to 20.5 psi before entering the engine; +25 means that the air/fuel mix is now being compressed to 39.5 psi. One pound of boost equals of Mercury (Hg).

Inches of Mercury (" Hg) Pounds of Boost
80" of mercury= +25 lb boost
67" of mercury= +18 lb boost
61" of mercury= +15 lb boost
46" of mercury= +8 lb boost
44.5" of mercury= +6 lb boost

Reliability of performance figures

When reading performance figures it should always be borne in mind that weight, the aerodynamic drag generated by different external fittings, the condition of the airframe and/or engine, and all sorts of other factors could influence how an aircraft performed. For example, the P-51's laminar flow wings needed to be kept as clean and smooth as possible; even relatively minor damage on the wing leading edges could drastically reduce top speed. The most accurate performance figures for the P-51 came from tests carried out at facilities such as the USAAF's Flight Test Engineering Branch, which was based at Wright Field near Dayton, Ohio and, for the RAF, the Aircraft & Armament Engine Establishment (A&AEE) based at Boscombe Down. North American Aviation carried out their own performance tests, as did the only other manufacturer of the P-51, the Commonwealth Aircraft Corporation (CAC) of Australia.

Table of P-51 Dimensions, performance and armament

Mustang I to P-51D
Mustang Mk I A-36 P-51A P-51B P-51D/K
Wingspan 37 ft 0 in (11.277 m) 37 ft 0 in (11.277 m) 37 ft 0 in (11.277 m) 37 ft 0 in (11.277 m) 37 ft 0 in (11.277 m)
Wing area 233.0 ft² (21.65 m²) 233.0 ft² (21.65 m²) 233.0 ft² (21.65 m²) 233.0 ft² (21.65 m²) 235.75 ft² (21.9 m²)
Length 32 ft 3.5in (9.83 m) 32 ft 3.5in (9.83 m) 32 ft 3.5in (9.83 m) 32 ft 3.5in (9.83 m) 32 ft 3.5in (9.83 m)
Height 12 ft 2 in (3.71 m) 12 ft 2 in (3.71 m) 12 ft 2 in (3.71 m) 12 ft 2 in (3.71 m) 12 ft 2 in (3.71 m)
Empty weight 5,990 lb (2,717 kg) 7,240 lb (3,284 kg) 6,800 lb (3,084 kg) 7,010 lb (3,179 kg)(without fuselage tank) 7,635 lb (3,363 kg)
Loaded weight 8,633 lb (3,915 kg) 10,000 lb (4,535 kg) 9,600 lb (4,354 kg) 9,800 lb (5,125 kg) Maximum permitted (straight flying)(without fuselage tank) 10,500 lb (5,262 kg) Maximum permitted (straight flying)
Engine Allison V-1710-39 Allison V-1710-87 Allison V-1710-81 Packard Merlin V-1650-3 (P-51-B-1NA to -5NA; P-51-C-1NT Packard Merlin V-1650-7
Power 1,220 hp (909 kW) at 10,000 ft (3,048 m) (44.7" Hg, 3,000 rpm) 1,325 hp (988 kW) at 5,400 ft (1,646 m) (47" Hg, 3,000 rpm) 1,330 hp (991 kW) at 11,000 ft (3,353 m) ("War Emergency" 57" Hg, 3,000 rpm) 1,490 hp (1,111 kW) at 13,750 ft (4,191 m) (61" Hg, low blower, 3,000 rpm) 1,590 hp (1,185 kW) at 8,500 ft (2,590 m) (61" Hg, low blower, 3,000 rpm
Maximum speed 382 mph (582 km/h) at 13,700 ft (4,176 m) 368 mph (570 km/h) at 14,0000 ft (4,267 m) 409 mph (597 km/h) at 10,000 ft (3,048 m) 441 mph (570 km/h) at 30,000 ft (9,144 m) 438 mph (651 km/h) at 25,000 ft (7,620 m)
Rate of climb ft/min (m/s) at ft (m) ft/min (m/s) at ft (m) 2,660 ft/min (13.5 m/s) at 14,750 ft (4,496 m) 3,520 ft/min (17,9 m/s) at 13,000 ft (3,962 m) 3,510 ft/min (17.8 m/s) at 7,000 ft (2,133 m)
Service ceiling ft (m) ft (m) ft (m) 41,800 ft (12,740 m) 41,800 ft (12,740 m)
Wing loading 37.0 lb/ft² (180.6 kg/m²) 42.9 lb/ft² (209.46 kg/m²) 41.2 lb/ft² (201.1 kg/m²) 42.5 lb/ft² (207.5 kg/m²) 44.5 lb/ft² (217.3 kg/m²)
Power/mass 0.14 hp/lb (0.23 kW/kg) 0.13 hp/lb (0.21 kW/kg) 0.14 hp/lb (0.22 kW/kg) 0.15 hp/lb (0.21 kW/kg) 0.15 hp/lb (0.22 kW/kg)
Combat range 480 mi (644 km) internal fuel,
  • 750 mi (1,207 km) 2 x 75 US gall (284 l) drop tanks.

400 mi (644 km) internal fuel,
  • 750 mi (1,207 km) 2 x 75 US gall (284 l) drop tanks.

400 mi (644 km) internal fuel,
  • 750 mi (1,207 km) 2 x 75 US gall (284 l) drop tanks.

500 mi (805 km) on internal fuel,
  • 880 mi (1,416 km) 2 x 75 US gall (284 l)drop tanks,
  • 1,000 mi (1,609 km) 2 x 110 US gall (416 l) drop tanks.

500 mi (805 km) on internal fuel,
  • 880 mi (1,416 km) 2 x 75 US gall (284 l)drop tanks,
  • 1,000 mi (1,609 km) 2 x 110 US gall (416 l) drop tanks.

Ferry range 900 mi (1,448 km) internal fuel,
  • 1,600 mi (2,575 km), 2 x 75 US gall (284 l) drop tanks,
  • 2,500 mi (4,023 km,) 2 x 150 US gall (568 l)ferry tanks.

900 mi (1,448 km) internal fuel,
  • 1,600 mi (2,575 km), 2 x 75 US gall (284 l) drop tanks,
  • 2,500 mi (4,023 km,) 2 x 150 US gall (568 l)ferry tanks.

900 mi (1,448 km) internal fuel,
  • 1,600 mi (2,575 km), 2 x 75 US gall (284 l) drop tanks,
  • 2,500 mi (4,023 km,) 2 x 150 US gall (568 l)ferry tanks.

1,200 mi (1,931 km), wing/fuselage fuel tank,
  • 1,830 mi (2,945 km), 2 x 75 US gall (284 l) drop tanks,
  • 2,120 mi (3,412 km),2 x 110 US gall (416 l) drop tanks.

1,200 mi (1,931 km), wing/fuselage fuel tank,
  • 1,830 mi (2,945 km), 2 x 75 US gall (284 l) drop tanks,
  • 2,120 mi (3,412 km),2 x 110 US gall (416 l) drop tanks.

Armament

  • 6x .50 (12.7 mm) M2 Browning, two in fuselage, two in each wing;
    350 rpg inboard guns, 280 rpg outboard; 400 rpg, fuselage.
  • 2 x 250 lb (113 kg) or 2 x 500 lb (227 kg) bombs

  • 4 x .50 (12.7 mm) M2 Browning, two in each wing; 350 rpg inboard guns, 280 rpg outboard.
  • 2 x 250 lb (113 kg) or 2 x 500 lb (227 kg) bombs

  • 4 x .50 (12.7 mm) M2 Browning, two in each wing; 350 rpg inboard guns, 280 rpg outboard.
  • 2 x 250 lb (113 kg) or 2 x 500 lb (227 kg) bombs

  • 6 x .50 (12.7 mm) M2 Browning, three in each wing; 400 rpg inner pair, 270 rpg outer four.
  • 2 x to 2 x bomb
  • provision to carry up to 6 x(with bomb racks) or 10 x (bomb racks removed) 5 in HVAR rockets on zero-length launchers.

CA-18 Mk 22 to F-82E
CA-18 Mustang Mk 22 XP-51G P/F-51H P/F-82E
Wingspan 37 ft 0 in (11.277 m) 37 ft 0 in (11.277 m) 37 ft 0 in (11.277 m) 51 ft 2 in (15.6m)
Wing area 235.75 ft² (21.9 m²) 233.0 ft² (21.65 m²) 233.0 ft² (21.65 m²) 417.63 ft² (38.8 m²)
Length 32 ft 3.5in (9.83 m) 32 ft 3.5in (9.83 m) 33 ft 4 in (10.16 m) 39 ft 1 in (11.91 m)
Height 12 ft 2 in (3.71 m) 12 ft 2 in (3.71 m) 12 ft 8 in (3.88 m) 13 ft 8 in (4.19 m)
Empty weight 7,120 lb (3,229 kg) 5,750 lb (2,608 kg) 7,148 lb (3,242 kg) 15,615 lb (7,083 kg)
Loaded weight 10,500 lb (5,262 kg) Maximum permitted (straight flying) 8,885 lb (4,030 kg) 9,420 lb (4,273 kg) Clean (no external stores) 24,864 lb (11,278 kg)
Engine Rolls-Royce Merlin 70 Rolls-Royce Merlin R.M 14 S.M Packard Merlin V-1650-9 Allison V-1710-143 port, -145, starboard
Power 1,375 hp (1,025 kW) at 13,500 ft (4,115 m) 54" Hg, low blower, 3,000 rpm. 2,080 hp (1,551 kW) at 22,800 ft (6,949 m) "War Emergency", 80" Hg, low blower, 3000 rpm. 1,930 hp (1,439 kW) at 23,500 ft (7,163 m) "War Emergency", 80" Hg, low blower, 3,000 rpm. 1,600 hp (1,193 kW) at take-off: 58" Hg, 3,200 rpm
Maximum speed 448 mph (390 knots) (722 km/h) at 14,000 ft (4,267 m) 495 mph (796 k/mh) at 22,800 ft (6,949 m) 487 mph (784 k/mh) at 25,000 ft (7,620 m) 461 mph (401 knots), (742 km/h) at 21,000 ft (6,400 m)
Rate of climb 3,510 ft/min (17.8 m/s) at 7,000 ft (2,133 m) 5,020 ft/min (25.5 m/s) at 20,000 ft (6,096 m) 4,680 ft/min (23.7 m/s) at 2,200 ft (570 m) 3,770 ft/min (19.15 m/s) at 13,000 ft (3,962 m)
Service ceiling 41,800 ft (12,740 m) 46,000 ft (14,021 m) 41,900 ft (12,771 m) 38,898 ft (11,856 m)
Wing loading 44.5 lb/ft² (217.3 kg/m²) 38.1 lb/ft² (186.1 kg/m²) 40.4 lb/ft² (149.7 kg/m²) 59.5 lb/ft² (290.6 kg/m²)
Power/mass 0.13 hp/lb (0.19 kW/kg) 0.23 hp/lb (0.38 kW/kg) 0.20 hp/lb (0.33 kW/kg) 0.13 hp/lb (0.19 kW/kg)
Combat range 500 mi (805 km) on internal fuel,
  • 880 mi (1,416 km) 2 x 61.5 imp gall (284 l)drop tanks,
  • 1,000 mi (1,609 km) 2 x 91.5 imp gall (416 l) drop tanks.

542 mi (872 km) on internal fuel
  • 936 miles (1,506 km), 2 x 75 US gall (284 l) drop tanks,
  • 1,104 mi (1,777 km), 2 x 110 US gall (416 l) drop tanks.

Ferry range 1,200 mi (1,931 km), wing/fuselage fuel tank,
  • 1,830 mi (2,945 km), 2 x 61.5 imp gall (284 l)drop tanks,
  • 2,120 mi (3,412 km), 2 x 91.5 imp gall (416 l) drop tanks.

1,350 mi (2,172 km) on internal fuel
  • 1,930 mi (3,106 km), 2 x 75 US gall (284 l) drop tanks,
  • 2,230 mi (3,589 km), 2 x 110 US gall (416 l) drop tanks.
  • 2,900 mi (4,667 km), 2 x 165 US gall (l) ferry tanks.

Armament

  • 6 x .50 (12.7 mm) M2 Browning, three in each wing; 500 rpg inner pair, 270 rpg outer four.
  • 2 x to 2 x bombs
  • 6 x 5 in HVAR rockets on zero-length launchers (three on each wing outboard of bomb racks).

  • 4 x .50 (12.7 mm) M2 Browning, two in each wing; 250 rpg.
  • Provision for one 75 US gall (284 l) drop tank on rack under each wing.

  • 6 x .50 (12.7 mm) M2 Browning, three in each wing; 390 rpg inner pair, 260 rpg outer four.
  • 2 x to 2 x bombs
  • provision to carry up to 6 x(with bomb racks) or 10 x (bomb racks removed) 5 in HVAR rockets on zero-length launchers.

  • 6 x .50 (12.7 mm) M2 Browning, center-section of wing, 400 rpg.
  • 8 x .50 (12.7 mm) M2 Browning, jettisonable pod under center-section, 400 rpg.
  • 8 x to 2 x bombs
  • provision to carry up to 25 x 5 in HVAR rockets, 5 each on "Christmas tree" racks disposed as 1 rack under wing center-section, 2 each outer wing panels.

References

Notes

Bibliography

  • Anderson, Peter N. Mustangs of the RAAF and RNZAF. Sydney, Australia: A.H & A.W Reed PTY Ltd, 1975. ISBN 0-589-07130-0.
  • Gruenhagen, Robert W. Mustang: The Story of the P-51 Fighter (rev. ed.). New York: Arco Publishing Company, Inc., 1980. ISBN 0-6680-4884-0.
  • Knaack, Marcelle Size. Encyclopedia of U.S. Air Force Aircraft and Missile Systems: Volume 1 Post-World War II Fighters 1945-1973. Washington, DC: Office of Air Force History, 1978. ISBN 0-912799-59-5.
  • Smallwood, Hugh. Spitfire in Blue. London: Osprey Aerospace, 1996. ISBN 1-85532-615-9.

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