avkozloff(at)roadrunner.c
Guest
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 Posted: Mon Sep 26, 2011 6:24 pm Post subject: Fwd: Galloping Ghost total loss cooling system. |
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Hey Pulsar Gang:
This is the most complete story of the GG I've seen that I just received
from my SZP neighbor who is a Rotary Engine expert.
--
Alex Kozloff
Pulsar I N190AK
Santa Paula, CA 93061
(949) 400-6364 Cell
(805) 525-1415 Office
_!_
------- Forwarded message -------
From: "Rotary Engine" <rotaryeng(at)earthlink.net>
To: "AAA Put this in the To box" <rotaryeng(at)earthlink.net>
Cc:
Subject: Galloping Ghost total loss cooling system.
Date: Mon, 26 Sep 2011 18:44:40 -0700
Paul,
I don't keep up with these racing planes, but what happened to the radiator
on this Mustang? How is the engine cooled? And I thought that the Mustang's
radiator ductwork was designed so that it actually yielded positive thrust?
If so, why remove it?
Csaba Csera
===================================================================================
From a pilot friend.
Galloping Ghost crash
Ok... here's the skinny on the accident....
A P-51 normally has two trim tabs. One on each elevator... This one had one
and other one was fixed in place.
He was warned about all the forces being put on that one tab. It failed.
He had at least a 10G load when the plane pitched up from the loss of the
trim tab and he went "nighty night" and probably never woke up.
Here's the "theory" of the crash from experienced racers.
In 1989 this type of thing happened to another pilot but he lived to tell
the story. When flying a P-51 at 450+mph you need to have full nose down
trim to keep
the plane level. The elevator trim tab broke off and the aircraft
immediately went in to a
10G climb, confirmed by the G-meter. The pilot came to, from the sudden
blackout and
realized he had slipped through the shoulder harness and was looking at
the floor of
the airplane. He was able to reach the throttle and pull it back to slow
down and was able
to recover and land.
Fast forward to 2011
Photo one is the airplane taxiing, note the pilots head in the canopy.
Photo two is typical oil canning as a result of the tremendous torque these
engines put out at high power. [The oil canning could be due to several
things.
One is the down force on the tail to counter the effect of a CG ahead ahead
of the lift. Another is the helical shape of the slip stream affecting the
vertical fin and horizontal stabilizer causing a torque on the fuselage.
Another could be caused by the violent snap roll the aircraft experienced.
Obviously the skin thickness was reduced when the aircraft was rebuilt
to reduce weight. The history of that is interesting as it was changed
on late model production P51's as well. PL]
Photo three is a photo of GG upside down with a missing elevator trim tab.
Note all you see is the back of the pilots head indicating he is being
forced down in the cockpit.
Photo four is a view of the left side nose down with the tail wheel
extended
and no view of the pilot. The tail wheel is held up by hydraulics only with
no mechanical uplock, thus indicating a high G-force causing it to extend.
Photos five and six are from the left side prior to impact, note no view of
the pilot and the tail wheel extended.
Photo seven is the debris just after the crash. To the right of center
above
the crowd it appears to be the wing with the leading edge down.
The people were mostly hit by chunks of concrete, asphalt and aircraft
debris. They were also hurt by the trampling of people getting out of the
way.
Peter
============================================================================
Its a myth the thrust from the P51 cooling system completely over came
the drag from the cooling system. It was still more drag than no
cooling system at all. One must add in the frontal area of the duct
and scoop. One reason the rotary adds less cooling system drag as
the engine is so compact the entire cooling system can be placed in the
cowl without adding frontal area.
However that is not to say the rotary has no cooling drag. The cooling
scoop acts more or less as a perpendicular flat plate extending down
from the cowl surface. The porosity of this plate
plate controls the cooling drag. If there is no rad in the duct the air
going
in the scoop will go out the exit only with a bit of skin friction drag.
The key to low cooling drag is come up with a rad or rad configuration
that achieves the cooling with a minimum of drag. The P51 rad and rad
configuration was not optimum. Later work on heat exchangers improved
the situation.
That is a long story and best told by my book "How to Cool Your Wankel"
and other books such as "Compact Heat Exchangers" and "The Aerodynamics of
Propulsion".
http://www2.leewardairranch.com/racing
"She [GG] now represents the leading edge of air racing technology with a
3,600 hp
racing engine, state-of-the-art boil-off cooling system, streamlined
aerodynamics
and a real-time data acquisition and management system."
Of course the amount of cooling required is directly proportional to
the amount of HP being generated. That is not the same as saying directly
proportional to speed as you have more mass of air to work with at higher
speeds.
The total loss boil off cooling system adds weight and will only work for
short
periods of time as found in Reno air races. The weight has a small affect
on drag. Probably the largest effect is a change in CG location that must
be trimmed by the horizontal trim tab.
Paul Lamar
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