Mustang history question

[mustangwatcher]

I'm looking for the EXACT # of days that it took North American to build the mustang. I keep hearing 120 days but that # varies with what website or "historian" you ask. Can you folks help me?

[warbird_patrick]

The NA-73X project that was contracted to North American Aviation saw the first prototype of what would become the P-51 Mustang roll out in 117 days. The NAA production plants were very well organized and under tight control and supervision. NAA was producing a P-51 Mustang about every 21 minutes

[Saville]

I thought the contracted time was 120 days; the airframe rolled out in 117, but delays in delivering the engine put them a day or so over the 120.

But I'm going form memory and I could be mistaken.

[Joe Scheil]

Remember too that the Mustang "Legend" kind of overlooks a few things to make a good story here. There was a lot of work in making the plane what it was...

In Jan or Feb 1940 NAA was going to be contracted to build P-40 airframes under license and Kindleberger knew this. According to Norm Avery in "North American Aircraft Vol 1" the P-40 was a vital asset to the US Defense effort, and no delay in deliveries could be tolerated, so therefore no additional aircraft could come from Curtiss lines to the RAF. Colonel Oliver Echols authorized British buyers to purchase under a "Cash and Carry" plan fighters from another source and use Curtiss engineering data if a different design was selected. In February, BPC asked if NAA could produce the P-40, and due to the difficulty of integrating the Curtiss system to the NAA system. Lee Atwood and Kindelberger knew they could design a better plane than the P-40. Planning a sales trip to Britain, the next two weeks were filled planning preliminar drawings and estimates. At this time Edgar Schmued began to collect people and almost instantly Ed Horkey was brought in, and the design of the airfoil which began rather benignly as the NA-5 to define the airfoil The rather benign project NA-50B was later changed to the NA-73X when the laminar flow airfoil was chosen. The extensive theoretical design work the NACA had done on these airfoils had been a long time in the making and NAA was the first to use this data, along with the XP-46 engineering data purchased from CUrtiss. The letter contract for 320 planes was prepared in April, on the condition that XP-46 data be used as a guide as the British had funded the development. Interestingly the NAA men found the XP-46 to not have been a low drag airplane at allm and the data while interesting was less advanced than the preliminary work already done by NAA! The Foreign release agreement was signed May 4 and specified two planes for the USAAC, 41-38 and 39. The NA-73 project was now official. There is no real data for when the first metal was cut... A notable point is that many of the young designers were eager to use their CALTECH experience as they were all from a very new and fertile crop of Caltech graduates. This institution played a big part in the genesis and tweaking of the Mustang. In October the latest Allison V-1710-39 was received, and taxi runs began on October 15, 1940. Two Brief flights were made on October 26, and the NX19998 was to fly six more times with Vance Breese before she was handed over to the company test pilot Paul Balfour. His 15 minute flight on Nov 20 was cut short when he incoorectly set the fuel selector and starved the engine...The airplane was repaired and began flying again January 11, 1941...The first production airplane rolled off in April 1941 and the plane AG345 flew within one year of contract issuance, meeting the goal set in the original contract. The first Mustang I's arrived in the UK in October 1941. The two Air Corps Mustangs flew May 20 1941, and arrived at Wright Field on August 24, 1941. The Mustangs languished for a while as the Wright Field project officers were so tied to the manufacturers they "Supported" that the XP-51's were not tested. Only after Grover Loening wisited the UK in 1942 was the matter brough to the attention of the Air Corps, and the testing of the XP-51's were transferred to Eglin field where it was finally discovered that this was a very well designed and potent fighter plane. General Hap Arnold stated later that it was the fault of the USAAC that they did not have the Mustang sooner. TO keep the production lines open, as the British had placed no further orders for 1942 now General Echols placed an order for 500 A-36 Invaders, finding an allocation for Attack aircraft funds. There was no additional money for fighters. TO have a General make a decision like this on his own is an amazing twist to history, as if the A-36 order had not come, the Mustang would have fallen out of production by April 1942. Rolls Royce began experimenting with 5 different Mustangs in July 1942 installing Merlins in the airframes, and NAA began work on its own conversion as well. The order for 400 Mustang III's was placed August 26, 1942 and the Mustang was now so good an aircraft that it could no longer be ignored by the Air Corps.

So how long did it take?