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Aviation History Month Day 20 - 20th of November 1940

It was on this day in aviation history the prototype for a new fighter, the NA-73X, registered as NX19998, ended upside down on its back in a farmer's field.

The Mustang prototype is on its back in a field. (© North American Aviation Inc.)

The first flight of the aircraft had already taken place on the 26th of October 1940, a total of 7 flights had been made up to this day. All these flights had been piloted by a freelance pilot, Vance Breese.

The eighth flight was to be a high-speed test, with North American Chief Test Pilot, Paul B Balfour, at the controls. The designer of the aircraft, Edgar Schmued, offered Schmeud to show him around the aircraft and asked him to take a seat in the cockpit to familiarise himself with the aircraft and run true the take-off and flight routine.

To which Balfour (apparently) responded that all airplanes are alike and he would not require a checkout.

Early in the morning (05.30 am) the groundcrew started the Allison V-1710-39 liquid-cooled V12 and let it warm up to operating temperature, after which it was shut down. Just prior to Balfour's arrival the engine was started again, although it took a bit more effort than before.

With Balfour at the controls, the aircraft got airborne at 07.10 in the morning, All went well until about 12 minutes into the flight when the Allison engine sputtered and stopped running. Balfour was too far from the airport to attempt a return to the airfield, so he opted to land in a farmers field, What he couldn't see from the air was that the field was freshly plowed and therefore the ground was very soft. As soon as the gear touched the ground it sunk in the soft soil and the prototype flipped over.

The aircraft being recovered (© North American Aviation Inc.)

Balfour managed to crawl out of the inverted aircraft, uninjured. The crashlanding was investigated and it was found that the engine had stopped due to fuel starvation, the pilot had forgotten to select the correct tank. Other rumors at the time were saying that carburetor icing was the cause.

After the aircraft was recovered it was returned to the factory to have the (extensive) damage repaired, the following damage was recorded by the investigation;

  • Engine housing damaged

  • Both wingtips damaged

  • Tail surfaces damaged

  • Top fuselage damaged

  • Other minor damages

Only 3 hours and 20 minutes of flight time had been recorded from the first flight till the moment of the crash landing.

Vance Brees has claimed that he had a bet with the executives of North American that Belfour would crash the aircraft on his first flight in the aircraft. If so he won the bet!

After the repairs were completed the test program of the NA-73X would continue and be developed into the world-famous North American P-51 Mustang. Although another chief test pilot was hired by North American, Robert C, Chilton.

NA-73X in flight with Robert Chilton at the controls. (© North American Aviation Inc.)

Specifications of the NA-73X;

  • Lenght 32 feet 2 5/8 inches (9.82 meters)

  • Wingspan 37 feet 5/16 inches (11.29 meters)

  • Empty weight 6278 lbs (2848 kg)

  • Take off weight 7965 lbs (2613 kg)

  • Engine Allison V-1710-38 V-12 engine Supercooled, Turbocharged Max 1490 hp at 3300 rpm

  • Max speed 332 knots (382 mph - 615 kph) at 13.700 feet (4176 meters)

  • Service ceiling 32.000 feet (9754 meters)

  • Fuel capacity 180 gallons (681 liters)

  • Range 750 miles (1207 km)

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