Jerry Hey wrote:

Paul, if you can find the time please look at a clearance issue
with
the simple tangential.  Consider a 6 inch O.D.  by 10 inch  long
muffler.  The exhaust pipes would enter it at the top so it hangs
down
six inches below the top  of the exhaust port. This is about one
inch
below the pan rail.   The motor mount tube that runs from the top
of
the gear receiver out to the Barry mount  is the problem.  I am
afraid
it will not clear the muffler.    If it clears no problem.  If it
does
not clear, we might be able to use a smaller diameter muffler, or
run
the exhaust pipes straight in centered on the muffler can,
raising
the
muffler 3 inches.  The muffler cannot be raised further without
getting
too close the the intakes.  Also, we can play with the distance
the
muffler can is from the exhaust flange.     Note: this is not the
P-51
style mount.

There are real problems with the P-51 mount because there is a
gear
leg
clamp built into the receiver.  It consists of a 2" x .125 slot
milled
into the bottom portion of the gear receiver.  The slot faces
forward.
There is a bolt across the slot that exerts  clamping pressure on
the
gear leg.  Because of the slot  I cannot weld a motor mount tube
to
the
front of the receiver and this makes it impossible to maintain
exact
on
plane relationship between the top and bottom tubes.  I am going
to
look at putting the clamp on the back of the receiver- Don't know
yet
if that  is possible.

I wish I could model this myself instead of constantly bothering
you.

  Jerry

What kind of airplane is this? What are the firewall dimensions and
hard
point dimensions. I need to know that to do a 3D.
Why not go up with it instead of down?
A simple tangential will fit no problem.
OK I'll check it.

BTW I picked up six feet of 3/4 thick wall steel tubing for the
spacers.
So don't buy any. Do you have a lathe to drill these out?

The 4130 sheet is in the sheet metal shop and he said it would be
done
this
week.

Paul

Sorry Paul,  this is the Tailwind. I should have been more clear.
You
already have modeled various engine mount configurations for it so
you
have all the data.     You cannot go up with the simple tangential
because the intake throttle body and runners are in the way.
Perhaps
if we went from a 6 inch can down to a 4 inch it might be possible.
The two outside tubes are not a problem.  It is the one that goes
from
the top of the gear receiver to the barry mount that I am concerned
with.   Jerry

OK I'll check. 29 inches center to center on the rubber bushings?

Paul

Yes on the 29.     On the steel spacer,  yes,  I have a lathe and can
do.   Jerry

OK Jerry the muffler will fit fine if you make it 10 inches long
instead of
12. Here is the 3D. Six inch diameter can. 2.5 inch down pipe.

Paul Lamar

Thanks Paul,   getting an engine mount and exhaust system to coexist
has been a head ache since the first day. I hope this is the solution.
Facing this problem over and over is "exhausting."         In your
drawing what is the distance from the firewall to the prop flange face
or to the Barry mount centers?   I will build accordingly.     Jerry

37 inches. The rad is currently 19 inches wide but there is still room
along side for a stock 5 inch wide oil cooler. The length of the rad is
currently 17 inches overall. It ends at the motor plate. You could pick 
up several more inches on rad  length to a common 24 inches overall by
(19 inch core) using  a side exhaust. In fact the side exhaust would get the heat 
out better. Many larger airplanes use side exhaust with no problem.
Monitor the CO in the cockpit and use diverters or turbulators to 
divert the exhaust gases. Also seal the doors well. Inflatable
door seals are easy to make and they also do wonders for cockpit noise.

Paul Lamar
 
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