On Mon, 23 Jul 2007 17:33:21 -0500, Big John
wrote in :

Larry

The Merlin could be throttle bursted (Idle to full throttle as fast as
you could move it) and you would have full power, 3000 rpm and 61
inche3s in 1 to 1 1/2 seconds. Only engine I ever flew with that kind
of response to throttle movement.

I would characterize that as a very significant latency in power
response to throttle control input. But your next paragraph seems to
suggest that to be the reverse.

So a pilot who slammed the throttle full open was presented with the
torque in that short period of time and unless you had some airspeed
or full rudder in, you were a goner.

I understand. But I presume the CFI taught not to do a burst-throttle
at low airspeed.

I'm still interested in the command latency you mentioned above. Did
the throttle have a similar latency throughout its travel, such that
the pilot was always anticipating the delay, or did the throttle
latency only occur, or was most pronounced, near the closed position?

As a result of the throttle latency, I can envision a situation where
the pilot is in a bit of a panic over his increasing descent rate
after reaching the apex of his arc immediately after the bounced
landing attempt. He smoothly applies throttle, but nothing happens.
About the time his initial throttle application begins to become
effective, he is facing a very hard second bounce, so in the vain
attempt to arrest his descent immediately, he applies more throttle as
he increases AOA, thus slowing the aircraft to the point that control
authority is insufficient to overcome the enormous torque that has
been erroneously commanded.

Is that scenario plausible?

At cruise you could burst throttle and you had plenty of rudder to hold
the torque. You still flew the engine smoothly however as no reason to
burst throttle.

I see.

I saw one instance where a sister Sq was making a heavy weight take
off mission. 6 five inch HVAR's (high velocity arial rockets), two 110
gallon drop tanks (we also used 75 gallon tanks on some missions) and
full ammo for the 6 guns.

My tent was near the end of the R/W and several of us were out
watching the other Sq take off. This one pilot (not the sharpest both
before and after) lined up and ran up to probably 40 inches (guess on
my part from engine sound) and started roll and we could hear him go
to full throttle. He rolled about 25 feet and we saw the elevator go
full down and the tail lifted off the ground. As soon as it lifted and
the tail wheel left the runway the bird made a abrupt 90 degree left
(with torque) turn and ran off runway into a 5 foot ditch. We didn't
have time to blink as it happened.

Wow!

We never lifted the tail until we had 30-40 mph so we could control
the torque with tail wheel. If you lifted tail a little bit early then
you had to be prepared to put a lot of rudder (even full if required)
in to hold the bird straight down runway.

So there were at least a couple of measures instituted to overcome the
P-51's tendency to torque roll uncontrollably.

30" max MP on the go around.

40 mph before lifting the tail on departure.

As Dudley has said, you need/needed to know the airplane and fly it
within its limits or it could kill you.

I suppose there are other gotchas than the immense torque.

As you can probably tell, I loved the bird back then and drool when I
hear a Merlin today as brings back many memories. )

Big John

Well, you should write them up, so that they aren't forever lost. I'm
sure there would be interest in such a memoir.