Memories of the P51 Mustang

Memories of the P51 Mustang

It would have been more complete if you mentioned that the P51 was designed by North American Aviation, and production was started in California. The P51A had two problems: First was that Allison promised NAA and Larry Bell a 1,150 hp supercharged V12 power plant for both the P51 and the Bell P39 Aerocobra but tried and failed to copy the front mounted gear driven supercharger that Rolls Royce had designed into the Merlin Engine.


Both companies were forced at the start of production to use the naturally aspirated 750 Hp version of the same engine, which was great on fuel and reliability, but was too weak for both planes. 


The second problem with the P51 was the wing air foil design which was a modification of a 1933 design.  The air foil actually created drag at speeds over 200 mph that require tremendous increases in horsepower to overcome, and the faster the wing flew, the worse the problem became. The solution came from Cal Tech or U. of Southern California with a new air foil called lamilar flow air foil which allowed the air behind the wing to "knit" back together without creating excessive drag.  It also allowed the centre of lift to be set to the centre of gravity of the plane, and the two stayed together as speed increased unlike the original air foil where the two centrelines separated making handling of a tail heavy plane at high speed nearly impossible. Boeing was given the air foil design and used it on the B29 with great success.


As for the engine in the Mustang, all but the P51A engines were made by Packard Motor Car Company in Detroit, Michigan as Rolls did not have the engine building capacity to supply the needs of their own planes, much less the Mustang and the Bell King Cobra.  A real fight broke out between Packard and Rolls as at the time, the Merlin was only 1350 hp. Packard interviewed British and American pilots who had flown the engine who repeatedly told Packard that the engine was not even "trying" when at full power.


Packard made small modifications to the fuel system and produced 2,000 hp on their first try. Rolls said no-way were they going to have their name on that engine as it would not hold together. Packard had collected info that the average British fighter plane was shot down with only 97 hours on the engine. Rolls demanded 2,000 hours with only normal oil, fuel, and air filter changes and valve adjustments. Finally the War Department picked a number of 1,650 Hp and that was what went into production at Packard. Spare engines were sent to England to support the P51B and C. Spitfire pilots got hold of a few then demanded that Rolls at least match the Americans engines, which they finally did.


I grew up in Chicago and two of my neighbours flew Mustangs as bomber escort in Europe and in Korea against Yaks and Migs. The other fellow flew his against Japan from March 1945 on until the end of the war in the pacific. Both men loved their Mustangs. As Chuck Yeager said; it is not an airplane, it is more like a well tailored suit that you put on it fits so well you canít believe it! It goes where you point it. Just fly it fast and use the see-kill-go combat approach.

I have flown a Mustang back in 1964 after I first got my licence and fell in love with it. This one had a 2,000 HP Rolls post war engine and could screw itself right into the sky.


The Mustangs only rival was the Bell P63 King Cobra which used the same engine but mounted it mid ship allowing faster turns with less wing area, and it used the lamilar flow air foil also. While it had almost the same profile as the much smaller P39, it had over 40% more wing area and over 200% more horsepower. Since the P39 was such a failure (under powered and wing loading too high), the War Department promised 100% of the production of the P63 to the USSR before even seeing it. I worked for a man who flew them over to Russia as part of the lend / lease program. He said it was the best plane he had ever flown.


Most of the Mustangs were built in Texas near Dallas.<o:p></o:p>
The Mustang I flew had been converted to have two seats. A second fully<o:p></o:p>
functional seat had been added after removing the big radio and the 85<o:p></o:p>
gallon fuel tank behind the pilot. I had learned to fly in a 1947 Piper Cub<o:p></o:p>
J3. After take off and climb to 8000 feet in the Mustang, the pilot offered<o:p></o:p>
me the controls. My Cub required about 6" of stick to the right or left to<o:p></o:p>
turn the airplane. Using the same on the right side of the Mustang stick<o:p></o:p>
caused the view above my head to turn from sky blue to green corn fields<o:p></o:p>
with no more effort that it takes to wink your eye.  There I sat hanging<o:p></o:p>
from my belts as amazed as the instructor was.  Finally he asked if I<o:p></o:p>
intended to continue inverted as we were not cleared for aerobatics. The<o:p></o:p>
plane rolled back to level.<o:p></o:p>
One problems with the P51D was that on take-off with a full load of fuel<o:p></o:p>
(with drop tanks and ammo) the plane at maximum weight AND was tail heavy.<o:p></o:p>
Instructors in the US trained the new pilots to burn off their drop tanks<o:p></o:p>
FIRST, then begin burning off fuel from the tank behind the pilot in order<o:p></o:p>
to get maximum range.<o:p></o:p>
The problem was that if a problem came up that meant returning to the field<o:p></o:p>
to land, the plane could not be landed in the tail heavy condition: it would<o:p></o:p>
flip upside down on its tail on approach.  Many green pilots were killed.<o:p></o:p>
The experienced pilots quickly retrained the green kids to take off on the<o:p></o:p>
wing tanks, then at about 2000 feet switch the tank behind the pilot to burn<o:p></o:p>
off the 85 gallons that was making the plane tail heavy during the remaining<o:p></o:p>
time it took to climb to 30,000 ft plus.  That way if they did have to drop<o:p></o:p>
the wing tanks to go after BF 109s for FW 190, the Mustang would not have to<o:p></o:p>
fight in a tail heavy configuration, which would mean sure death.<o:p></o:p>
Landing the Mustang had some Do's and Don'ts. The plane required itself to<o:p></o:p>
be flown onto the runway with ample power. Too many green pilots would find<o:p></o:p>
themselves "short" of the runway and at just above stall speed, trying to<o:p></o:p>
add a big burst of power from the Merlin. The Merlin is not a high rev<o:p></o:p>
engine, but it IS an extremely high torque engine. Opening the throttle<o:p></o:p>
would cause an immediate increase of torque to be applied to the massive 4<o:p></o:p>
bladed propeller which reacted slowly causing reaction torque causing the<o:p></o:p>
plane to roll in the opposite direction of the propeller rotation, usually<o:p></o:p>
causing a stall and crash since there was no time to apply opposite stick to<o:p></o:p>
correct.  Most experienced Mustang drivers landed well above stall speed and<o:p></o:p>
slightly long to assure that they would not be caught with this problem.<o:p></o:p>
This high torque problem showed up on the F6F Hellcat and the Corsair which<o:p></o:p>
used the same design prop. Both Navy and Marine pilots reported the problem<o:p></o:p>
which was very bad on flat top landing where there was no margin for error.<o:p></o:p>



Thanks to Barry Biard - Too Old To Fly Anymore!

MLA Citation/Reference

"Memories of the P51 Mustang". 2014. Web.

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