Some interesting Mustang trivia from a UK site:
http://www.historylearningsite.co.uk...51_Mustang.htm



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.

(note: NACA 66 series airfoil and a slightly thinner wing than that used
by earlier Mustangs)

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 can’t 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.

The Mustang I flew had been converted to have two seats. A second fully
functional seat had been added after removing the big radio and the 85
gallon fuel tank behind the pilot. I had learned to fly in a 1947 Piper
Cub J3. After take off and climb to 8000 feet in the Mustang, the pilot
offered me the controls. My Cub required about 6" of stick to the right
or left turn the airplane. Using the same on the right side of the
Mustang stick caused the view above my head to turn from sky blue to
green corn fields with no more effort that it takes to wink your eye.

There I sat hanging from my belts as amazed as the instructor was.
Finally he asked if I intended to continue inverted as we were not
cleared for aerobatics. The plane rolled back to level.

One problems with the P51D was that on take-off with a full load of fuel
(with drop tanks and ammo) the plane at maximum weight AND was tail
heavy.

Instructors in the US trained the new pilots to burn off their drop
tanks FIRST, then begin burning off fuel from the tank behind the pilot
in order to get maximum range.


The problem was that if a problem came up that meant returning to the
field to land, the plane could not be landed in the tail heavy
condition: it would flip upside down on its tail on approach. Many
green pilots were killed.


The experienced pilots quickly retrained the green kids to take off on
the wing tanks, then at about 2000 feet switch the tank behind the
pilot to burn off the 85 gallons that was making the plane tail heavy
during the remaining time it took to climb to 30,000 ft plus. That way
if they did have to drop the wing tanks to go after BF 109s for FW 190,
the Mustang would not have to fight in a tail heavy configuration,
which would mean sure death.


Landing the Mustang had some Do's and Don'ts. The plane required itself
to be flown onto the runway with ample power. Too many green pilots
would find themselves "short" of the runway and at just above stall
speed, trying to add a big burst of power from the Merlin. The Merlin
is not a high rev engine, but it IS an extremely high torque engine.

Opening the throttle would cause an immediate increase of torque to be
applied to the massive 4 bladed propeller which reacted slowly causing
reaction torque causing the plane to roll in the opposite direction of
the propeller rotation, usually causing a stall and crash since there
was no time to apply opposite stick to correct. Most experienced
Mustang drivers landed well above stall speed and slightly long to
assure that they would not be caught with this problem.