P-51A (Mustang II)

Design changes

Last of the Allison Mustangs


Serial numbers

3-Way drawings



Design changes

By August 24th, 1942, the USAAF had more money to purchase fighter aircraft and thus an order was immediately placed for 1,200 NA-99 fighters. They were designated P-51A by the USAAF and essentially the P-51As were very similar to the A-36 Apaches.

The most noticeable differences are:

  • Removal of the dive bombing equipment
  • A new Allison V-1710-81 engine rated at 1,200 horsepower, driving a larger 10-foot-9-inch diameter, 3-bladed Curtiss Electric propeller, increasing top speed to 409 mph (658 km/h) at 10,000 ft.
  • New armament of four .50 caliber Browning machine guns, 2 in each wing (inboard guns had 350 rounds each and the outboard guns 280 rounds each). The chin guns were removed.
  • A fixed belly scoop
  • One wing rack on each wing, able to carry either 75 or 150 gallon drop
  • L-shaped pitot tube
  • One landing/taxi light

P-51A cockpit layout
P-51A cockpit layout

N-3 Gunsight
Left: carburator air scoop system - Right: the N-3 gunsight

Last of the Allison Mustangs

The first P-51A flew on February 3rd , 1943, and was piloted by Ben Chilton.

P-51A production line (NAA)The P-51A was the first ever fighter version of the Mustang to be purchased and used by the USAAF. Of the 1,200 aircraft which were ordered only 310 were actually built between March and May of 1943 (by then the first XP-51B had flown with the Merlin engine and the USAAF opted for that version). Because of constant changes in production, a block numbering system is used so that personnel can readily identify equipment carried in a certain airplane by referring to the dash number following the model designation. There were three production blocks which carried the following serial numbers:

43-6003 through 43-6102 (P-51A-1-NA)

43-6103 through 43-6157 (P-51A-5-NA)

43-6158 through 43-6312 (P-51A-10-NA)

Of the 310 P-51As built, 35 were fitted with twin K-24 camera installations and were designated as F-6Bs. The British received 50 aircraft which they named Mustang II (serials FR890 FR 939).

Thanks to the use of drop tanks, range increased from 750 miles at 300mph (with internal fuel) to 2,350 miles (with drop tanks).

There were still a few drawbacks on the P-51A however:

  • Thanks to the new Allison, the P-51A had better performance then it's predecessors but still lacked performance above 22,000 ft.
  • Due to the thin wings, the four 0.50 caliber guns had to be mounted almost laying on their sides. As a result the ammunition belt feeds were installed with a kink in order to direct the bullets into the guns. In high-G maneuvers (which are obviously common during air-to-air combat) this resulted in unfortunate gun jams.

The P-51A was also the last Mustang that used the Allison engine. About 1,580 Allison-powered Mustangs were manufactured in total. The US operated the P-51A mainly in Asia with the 23rd , 311th and 1st Air Commando Groups.

The USAAF finally realized the potential of the Mustang at that time and in all, the P-51s were praised by their pilots and ground crews for its high performance (at lower altitudes) and its reliability.

Little did they know that one more modification would lead to Mustang magnificence.

Very few Allison Mustangs have survived throughout the years. Two are currently still flying: P-51A-10NA (43-6251) "Miss Virginia", operated by the Planes of Fame Air Museum, based in Chino and P-51A-1NA (43-6006) "Polar Bear", operated by Jerry Gabe. One of the original XP-51B's is kept in the EEA Airventure Museum in Oshkosh , Wisconsin .

Photo courtesy of www.warbirddepot.com
P-51A-10NA (43-6251) "Miss Virginia" (photo by

P-51A-1NA Polar Bear (Photo by Christophe Haentjens)
P-51A-1NA (43-6006) "Polar Bear" at the 2007 Gathering of Mustangs & Legends

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Copyright © 2007 Christophe Haentjens - http://www.crazyhorseap.be