Jumbo Tanker Accident

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.

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. 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 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.

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.

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

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
******************************************


On Mon, 23 Jul 2007 20:31:47 GMT, Larry Dighera
wrote:

On Mon, 23 Jul 2007 14:31:46 -0500, Big John
wrote in :

Last one of these accidents I saw, the pilot (from a sister Sq who
made wheel landings) used to much power on go around and torque rolled
into sandy soil next to runway (did not burn).

Thank you for the firsthand information.

What puzzles me is why, when the PIC finds that he is unable to
control the torque, he doesn't reduce the power? Or is the power
application so swift that there isn't time to react to the torque
roll?

Commercial pilots are taught to apply power smoothly (slowly), it
would seem that there would be time to do that in this sort of
situation. Am I wrong?

On Mon, 23 Jul 2007 17:17:30 -0400, Dudley Henriques
wrote in
:


What puzzles me is why, when the PIC finds that he is unable to
control the torque, he doesn't reduce the power? Or is the power
application so swift that there isn't time to react to the torque
roll?

Commercial pilots are taught to apply power smoothly (slowly), it
would seem that there would be time to do that in this sort of
situation. Am I wrong?

No, you're right, and that is exactly how it should be done; quickly but
extremely smoothly, with adequate rudder and aileron applied together.
As for what's "puzzling you"; in these airplanes you don't get the
luxury of finding out you can't control the torque on a go-around. By
that time it's way too late, and reducing the power may not be an option
due to the flight configuration and/or circumstances.

You mean, if you see that the rudder is against the stop, and you're
starting to roll further to the right, you can't reduce the power to
counter the torque induced roll? What would happen? You'd at least
land/crash on the mains instead of the canopy, wouldn't you?

You get one shot in these airplanes to do it right; just one.

To do it right, perhaps. But if you're out of control, you still have
some options other than letting the torque flip you over, don't you?
Or is there too much inertia with that big prop to expect a throttle
reduction to reduce torque fast enough to prevent it from rolling you
inverted?

The way to control torque in the Mustang is to know exactly the conditions
that will cause the issue and take the proper steps to prevent it from
happening.
Dudley Henriques

Okay. But once the PIC realizes that s/he's going to "scratch the
paint," the PIC's mind set should be to minimize the potential injury.
Wouldn't cartwheeling be preferable to landing on your head?

What is approach speed for a P-51 anyway?

Larry Dighera wrote:
On Mon, 23 Jul 2007 17:17:30 -0400, Dudley Henriques
wrote in
:

What puzzles me is why, when the PIC finds that he is unable to
control the torque, he doesn't reduce the power? Or is the power
application so swift that there isn't time to react to the torque
roll?

Commercial pilots are taught to apply power smoothly (slowly), it
would seem that there would be time to do that in this sort of
situation. Am I wrong?

No, you're right, and that is exactly how it should be done; quickly but
extremely smoothly, with adequate rudder and aileron applied together.
As for what's "puzzling you"; in these airplanes you don't get the
luxury of finding out you can't control the torque on a go-around. By
that time it's way too late, and reducing the power may not be an option
due to the flight configuration and/or circumstances.

You mean, if you see that the rudder is against the stop, and you're
starting to roll further to the right, you can't reduce the power to
counter the torque induced roll? What would happen? You'd at least
land/crash on the mains instead of the canopy, wouldn't you?

You get one shot in these airplanes to do it right; just one.

To do it right, perhaps. But if you're out of control, you still have
some options other than letting the torque flip you over, don't you?
Or is there too much inertia with that big prop to expect a throttle
reduction to reduce torque fast enough to prevent it from rolling you
inverted?

The way to control torque in the Mustang is to know exactly the conditions
that will cause the issue and take the proper steps to prevent it from
happening.
Dudley Henriques

Okay. But once the PIC realizes that s/he's going to "scratch the
paint," the PIC's mind set should be to minimize the potential injury.
Wouldn't cartwheeling be preferable to landing on your head?

What is approach speed for a P-51 anyway?


No. First of all, the term "full rudder" as relates to a go-around needs
some amplification for you if you are talking P51's. (Actually all
airplanes but especially the Mustang)
What corrects torque is aileron NOT rudder as many pilots believe. You
can sit on the ramp in a Mustang and power will compress the left main
gear strut. If you try this at over 40 inches standing still in a 51, it
will jump the chocks..it has THAT much power! Torque correction is in
ROLL, not in yaw, and this requires right aileron.
Anytime the propeller disc is slanted to the relative wind (you are
moving)you have P Factor. Anytime the propeller disc is transitioning in
pitch you have gyroscopic precession. With power applied you have spiral
slipstream on the vertical tail surfaces.
ALL of these left turning forces are active on the 11'3" Hamilton
Standard propeller mounted on the nose of a P51.
If you bounce this airplane, you had too much forward stick in hand
through the touchdown and the tail was probably too high. In the 51,
this is a classic bounce scenario, usually won't happen unless you're
landing hot.
When an airplane like a 51 bounces on touchdown, you have to be quick
and you have to be SMOOTH on both the controls and the throttle. Ham
fist either or both and it can spoil your day.
You recover from the bounce exactly as I described in my prior post or
you take it around exactly as I described it in the same prior post.
You NEVER allow a Mustang to bounce through an unassisted decelleration
letting it go high on you in the bounce.
As for torque. In applying power during a bounce correction, you have to
consider torque by holding in enough right aileron to correct it; P
Factor in any condidion other than stable level flight where both sides
of the blade arc are at equal aoa, and most certainly gyroscopic
precession 90 degrees to any deflection of the propeller disc while in
pitch transit. As power is applied, you will also be dealing with
spiraling slipstream. You correct with perfectly blended right aileron
for the torque, right rudder for the GP, PF, and SS. It goes without
saying that with all this going on, you don't EVER....and I mean EVER
allow a P51 to bounce through a bad touchdown to the point where full
application of these controls can't handle the situation. If you find
yourself in this condition, you are about to crash and power reduction
at that point would most likely not prevent that crash and would most
likely simply alter the angle at which the Mustang impacts the ground.
To answer your question specifically; cutting the power would certainly
aid in stopping the forces acting on the airplane, but that scenario
would most certainly be coming way too late based on the fact that the
need to do it would have already put the airplane beyond recovery
parameters considering ALL factors.

You asked about approach speed for the Mustang;
At the GW I flew the airplane most of the time, I used 150 for a normal
pattern, turning base to final dropping it to 120; then over the fence
at about 115 decelerating on down into the flare.
Dudley Henriques

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.

On Wed, 25 Jul 2007 14:51:12 -0500, "Neil Gould"
wrote in
:

Compared to what?

I am rewarded with an immediate increase in power when advancing the
throttle of an IO-360 or O-540; there is no significant delay between
opening the throttle and an increase in power.

But perhaps I was misinterpreting what was said. Of course there is
some delay before a burst-throttle and the engine reaching full power
due to the necessity of accelerating the mass of the moving parts
involved.

Recently, Larry Dighera posted:

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.

Compared to what? I can't think of any engine that responds more quickly
than that.

Neil
(not a P-51 pilot, but my father was...)

Larry Dighera wrote:


But perhaps I was misinterpreting what was said. Of course there is
some delay before a burst-throttle and the engine reaching full power
due to the necessity of accelerating the mass of the moving parts
involved.

I think he's saying that any delay is even shorter in the Merlin, but
even more than that, the power differential in that Merlin between
cruise or whatever and "burst throttle" is magnitudes more than in your
360 or 540. These two things together are maybe what get you into
trouble if you are not careful and power is not increased smoothly.
I have a flight manual for the P-51 that I got when I flew Crazy Horse.
On take-offs and go-arounds it also says to advance the power "smoothly."

Recently, Larry Dighera posted:

On Wed, 25 Jul 2007 14:51:12 -0500, "Neil Gould"
wrote in
:

Compared to what?

I am rewarded with an immediate increase in power when advancing the
throttle of an IO-360 or O-540; there is no significant delay between
opening the throttle and an increase in power.

The original statement was the the Merlin would go from idle to _full
power_ in 1 to 1-1/2 seconds. I seriously doubt that your IO-360 or O-540
will do better, especially considering what the "full power" of a P-51 is.
;-)

But perhaps I was misinterpreting what was said. Of course there is
some delay before a burst-throttle and the engine reaching full power
due to the necessity of accelerating the mass of the moving parts
involved.

Absolutely.

Neil