Thanks much Pete. That's the exact quote I was getting on this, so this
has to be the training manual in question.
I asked around the P51 community a bit on this and have heard back from
Vlado Lenoch and Glenn Wegman. Neither mentioned the manual per se, but
not to my surprise, agreed with me that there are no basic issues in
slipping the 51 save doing it below 200 feet due to the quick and
sometimes unpredictable payoff behavior of the wing at low speed and
high angles of attack.
When I was told about this being in this manual, I immediately dove into
my dusty old desk and dug out the old dash 1 for my airplane. Under
rudder control, it plainly states that sideslips are no issue at all,
and in fact mentions sideslips by name.
My take on the training manual is that pilots coming out of Advance in
the AT6 and transitioning into 51's during lead in fighter training were
faced with dealing with the laminar characteristics of the Mustang
coming off the comparatively higher lift characteristics of the T6,
which could be slipped like mad. I'm fairly certain, although I could
never prove this, that the Training Command thinking at the time was to
save lives and conserve sheet metal. The Mustang really doesn't need to
be slipped on final due to the extremely high drag of the last flap
position at 50 degrees (47 actually) plus running up the prop to low
pitch against the stops is like dragging your feet in the mud in this
airplane. My guess is that ATC just decided after looking at the log
books for total time of the guys transitioning into the Mustang that
having this restriction saved them a lot of trouble writing accident
reports, since it wasn't necessary to slip the airplane anyway.
The wording is interesting though, and I guess one could stretch a point
in justifying the restriction by noting control response degradation in
the left side of the Mustang's envelope.

About the military/civvie conversions;
Mine had the old radios and junk in it.
The military Mustang had a bunch of crap in it that more or less kept
the cg in limits. When the guys started gutting them and converting
them, they took a lot out and threw the cg forward enough that they
needed weight in the tail or at least had to be REAL careful landing
them. It wasn't uncommon to see full nose up pitch trim on some of them
after 3 pointing them.
I always landed the Mustang with some speed on the airplane, tail low on
the mains anyway, but the cg can be a problem for the pilots who like to
do 3 pointers in the airplane.
I remember Vlado telling me something about Moonbeam's configuration,
but I forget if he has the cg issue. I would assume he does, as Collins,
Bendix, and King, are a whole lot lighter than that old crap we had in
there :-))
Dudley
I guess the bottom line on what the manual says would be;
Manual says "no slips"
Dash 1 says, "No slip restrictions"
I would say, "no problem at all, but not under 200 feet"
Other P51 pilots are checking in with "I do it"
Puzzling how the government does things isn't it? :-))))
Dudley


"Peter Stickney" wrote in message
...
In article et,
"Dudley Henriques" writes:
Thanks much Pete. This training manual supposedly says that the 51
can't
hold a slip due to aileron or rudder issues that make it straighten
out
if the pilot tries to hold it in a slip.
I've done hundreds of slips to both sides in this airplane and never
had
such an issue. I'm assuming the training manual was written as an aid
in
transitioning low time pilots into the high performance 51, as the
dash
one specifically states that slips are not an issue.
The 51 does pay off fairly quickly on landing if you get it too deep
into the left side before touchdown and it can be a bit hairy. You
generally wouldn't hold a slip in the 51 under 200 agl for safety
reasons, and between the last flap position drag index and running
the
prop up to low pitch, you really don't need slips in the 51, but I'm
really interested in researching the obvious conflict between the
training manual, the dash1, and my own personal experience in the
airplane along with every other 51 driver I have asked about this.
Thanks much for the help. I'll watch the thread for you.

Dudley,
Here's what I have. From AAF Manual 51-127-5, "Pilot Training Manual
for the P-51 Mustang", 15 August 1945.

Page 66:
"The P-51 does not hold a sustained sideslip. The aileron control is
not sufficient to hold the airplane in a sideslipping angle. However,
you can sideslip it long enough to avaid enemy fire in combat. When
any sideslipping is attempted, be sure to recover completely above 200
feet."

In truth, that sounds a bit fishy to me, as well. Of late, I've been
wading through the incredible amount of Tech Reports that have been
made available on the NACA Tech Reports Server. (About 10,000
inindexed
files. I'm not complaining. Indexing them is a huge effort, and I
_like_ roaming through huge reams of extreme Aero-Geekery. Color me
strange.) Among them are the reports on the wind tunnel test series
that were run to prove out the extended fin used on the P-51H (And the
Temco TF-51Ds from the 1950s, and the Cavalier '51s). They show that
for the P-51D configuration, with the great big long nose, the
direction stability's a bit weak at low speeds. (Not bad, mind, but
they wanted it better) Even though the '-51's ailerons get a bit
mushy
when slow, that ahouldn't have been a problem.

I've also got a copy of the report of the modern-era flight tests
comparing the F6F, P-51, P-47, and F4U by John Ellis and Chris Wheal
that were published in _Cockpit_. (The journal of teh Society of
Experimental Test Pilots)

I regards to sideslip behaviour, they make this comment:
"Steady heading sideslips in cruise and land configurations revealed
nothing out of teh ordinary beyond the fact that the rudder forces in
both the Hellcat and Corsair were extremely high. Full rudder
sideslips generally required 50-60% of available aileron deflection in
cruise at 180-190 kts, and 20-50% aileron in the landing
configuration."
That doesn't sound like it can't sideslip to me.

There is one thing in the _Cockpit_ article that I find a bit odd.
They rate the P-51 as being rather heavy in pitch. According to their
data, they measured 'bout 20 lbs/G. That doesn't seem right to me -
from other data, I'd have thought that about 6 lbs/G would have been
more like it. Now, I know that late-model P-51Ds had bobweights in
the pitch system to help counteract the really light forces that you
got with an extremely aft CG, such as when the fuselage tank was
installed & filled. Would having the bobwights in the airplane with a
forward CG heavy things up to that extent? Or could hte airplane have
been out of rig? (If it helps, the P-51D they used for the tests was
N51HT, Harry Tope's airplane.


--
Pete Stickney

Without data, all you have are opinions