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Mustang l - ll story.

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With all the interest in the early Mustangs, here is a short synopsis. 

When the RAF asked NAA to build their designs under license, NAA did one better and designed a brand new aircraft, in about 120 days. The RAF placed an order for 320 aircraft and named them the “Mustang”.  The first was the Mustang l.

Mustang l:

The first batch of Mustang Is were the NA-73, basically the same design as the XP-51 using the original powerplant, the Allison V-1710-39.
NAA kept the first production aircraft, AG345, for a test mule and to work out various concerns.
The RAF received the first Mustang Is in October, but 20 aircraft were lost at sea during shipment. When the RAF perfomed tests on the Mustang I, they were very enthusiastic about the new fighter. It was 30 mph faster than the Spitfire and had more than double the range. 
AG348 was the last Mustang with the short nose intake as problems were foundwith carburetor induction during high-angles of attack. NAA then extended the nose intake right up to the spinner. This was a similar fix to what Curtiss performed with some Tomahawk variants. Also, up to serial AG348, Mustangs we’re basically hand assembled, but starting with AG349, they were built on an assembly line. 
In December 1940, the RAF added another 300 aircraft to their order.
Still called Mustang I, the new NAA designation was changed to NA-83, due to an improved  flared ejector exhaust.

Mustang Ia:

March of 1941 when amend-Lease was passed, the US placed an order for 150 more Mustangs to be sent to Britain. This allocation was NA-91, RAF designation of Mustang Ia. The Mustang Ia was equipped with four Hispano 20mm cannons installed in the wings, with the two nose guns deleted.  They packed one HELL of a punch.
Out of the 150 ordered, only 111 were serialed for the RAF and probably less than that actually received. 

After Pearl Harbor, the US Army held the remaining order of NA-91s Thea t for Britain. These, about 55, were designated P-51 and were fitted with four .50 cal guns instead of the cannons.

Aerial cameras were installed on some and they were designated F-6.

The US Army also developed a dive bomber version, called the A-36 "Apache". 

Mustang II:

The US Army placed their second order for P-51s, this time the P-51A, NA-99. 1,200 were ordered in August of 1942. The differences between the P-51A and the P-51/Mustang I was a new Allison V-1710-81, no nose guns, just four .50 guns in the wings, a fixed belly scoop and they were plumbed for drop tanks.  The Mustang configuration was getting closer to what we know today…

Since the RAF was shorted on the last order, 50 NA-99s were designated Mustang II and sent to the RAF.  The new Allison had a significantly improved supercharger which greatly increased mid-altitude performance. The Mustang II had a top speed of 412 mph at 10,000 feet, making it the fastest mid-altitude fighter of it’s time. Yes, the P-47 and the Tempest were faster, but they were much later developments and had twice the horsepower. 

With the development of the Merlin installation, the full order of NA-99 was cut short for the introduction of the P-51B/C.

I believe that production of Allison powered Mustangs ceased at that time.  
It’s interesting to note that a well tuned Allison powered Mustang could run away and hide from the Merlin powered Mustang at mid altitudes.

A total of 1,579 Allison powered Mustangs were produced.

If anyone wants to add to this, feel free, but we must remember that if it wasn’t for the RAF and their need of a hot new fighter, we would have never had the Mustangs we know and love.

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Thank you for the information and research on the early Mustangs. I sure wish Tamiya would see the light and do the series a series of early Mustangs through the B/C. Of course, the odds are slim to nil of this every happening in 32nd scale but maybe 48th scale, as their excellent P-51B/C is getting a bit aged in the tooth these days.


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4 hours ago, Spitfire said:

Nice summary, I do like the early Allison Mustangs, shame they are so neglected by the mainstream model makers.



No problem, Dennis. I may be off on a few of the specifics, but I think I’m pretty close. Feel free to change or add to anything.  
People seem eager to discount the Allison powered Mustangs as a lesser machine, but they were the best in the world at the time.  Those 4 Hispanos packed one helluva punch, although I still scratch my head at both Britain and Germany insisting on staying with rifle caliber machine guns as their primary armament. Britain with the 303, and Germany with the 7.92mm (8mm Mauser).

The Allison Mustang was an excellent photo ship, a great ground attack machine, and an excellent mid altitude fighter that only got better as the Allison matured. It had crazy range, and was insanely fast. It served the RAF well in Europe, finding it’s spot quickly, but absolutely shined in the MTO and the Far East.  The work it did with the Air Commandos is legendary.  As far as I know, the only reason they were phased out is because NAA stopped building them.

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  • 4 weeks later...

I bet they were well appreciated when they arrived. 4 x 20mm cannons in an early  1941 fighter ....Typhoon was so equipped from September 41 but had all the problems ...not so sure about the Hurricane IIc ....summer /autumn 1941 ?

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On 2/24/2023 at 9:06 AM, Clunkmeister said:

One thing with the Allison powered Mustangs.

Notice that the inner gear doors are always locked up when parked. 

I think all Mustangs did this but later models the hydraulics would bleed off and the would come down but went back up when started....harv

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