Friday, July 1, 2022

A good idea in theory, but the aircraft refused to take off

The P-82 was two P-51 Mustangs joined together to form a long-range protective fighter to escort B-29 bombers for the invasion of Japan. Two atomic bombs took care of the invasion plans, but the Army Air Force went ahead with production of the Twin Mustang.

All aspects of the aircraft were precisely engineered, which is good for things that take to the air.

“The XP-82 was to be powered by two Packard-built Rolls-Royce V-1650 Merlin engines. Initially, the left engine was a V-1650-23 with an additional gear in the propeller reduction box to allow the left propeller to turn opposite to the right propeller, which was driven by the more conventional V-1650-25.

“In this arrangement both propellers would turn upward as they approached the center wing, which in theory would have allowed better single-engine control. This proved not to be the case when the aircraft refused to become airborne during its first flight attempt.

“After a month of work North American engineers finally discovered that rotating the propellers to meet in the center on their upward turn created sufficient drag to cancel out all lift from the center wing section, one quarter of the aircraft's total wing surface area. The engines and propellers were then exchanged, with their rotation meeting on the downward turn, and the problem was fully solved.

https://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang

Slide rules and pencils and paper, combined with aircraft engineering experience, said, “This is how it will work.” Reality, though, was something else entirely. You have to wonder, “What was the test pilot’s reaction when the aircraft would not leave the ground?”

 

2 comments:

  1. That Murphy character sure likes to pop up when he is least expected, doesn't he? I'll but that pilot did indeed have a rather perplexed expression on his face, but not as perplexed as the engineers.

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  2. Every airplane has a takeoff speed, and I would guess the test pilot was surprised when the YP-82 refused to follow written expectations.

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