Paul,

You hit the nail on the head. The look of this plane was 100%
inspired by what I thought would look good. Basically it's a WAR
Replica aircraft with a composite fuselage (as opposed to wood
frame), and a rotary instead of a 0-200 or comparable. I wanted a
aircraft that was uniquely my own so I picked the planes I liked the
most (Corsair, Spitfire, Mustang, Fw-190) and combined all the style
elements that I liked into one plane. And yes the cowling was most
definitely inspired by looks not practicality but the volume the
radial style cowling offers is it's own practicality. I tried
raising the engine up until the spinner was tangent to a curve that
was drawn from the top of the firewall and looked at component
locations. About the only thing that didn't give me an immediate
headache trying to figure out where it would go is the alternator.

As you can see in the attached screen grab there isn't much room
between the firewall and the main spar (which goes all the way to
the bottom skin). The grey tube is your ejector and there just isn't
any room for it unless I hang it under the plane. It looks a lot
bigger when placing it right up against the rest of the plane. I wear
size 13 shoes and having a tunnel go between them although plausible
would make me want to jump out of my skin (I'm slightly
claustrophobic) if I couldn't have any room for my feet side to side.
I have built a mockup of the cockpit if you were wondering.

I moved the exhaust outboard a little and that allowed the center of
the ends of the motor mount tubes to get within about 1" of each
other at the motor mount plate. Hopefully that will be enough. It
does require a bulge on the side of the cowling. Aircraft design is
all about compromises and the bulge is the one I'm most comfortable
with. I can live with it being a little noisier and having a little
higher fuel consumption. In exchange I get a whole lot of space to
put everything and a good looking plane as well. And the bulge will
add a little more Fw-190 to the flavor.

So basically unless there is some major functionality issue that
hasn't been mentioned yet I think my basic course is set.

Will Aldridge

That's a beautiful airplane no doubt about it.

Please send me the 3DM on the pilot.

Paul Lamar


Paul,

It's pretty crude but you're welcome to it. It's roughly a 95% guy.
Maybe about 6'2". I measured myself to make him and broadened the
shoulders and hips a little and made him slightly taller just so I
knew there would be some wiggle room in the cockpit. And he's wearing
size 13 shoes.

Will

Thanks. He is about my size with the same shoes :)

I think you might have problems with the muffler. Most people do.

Could you make the fuse a little deeper oval? The intersection drag
with the wing would be less and you could get the muffler in there.
I'll get my Hoerner Fluid Dynamic drag out and scan it shortly.

Not the whole thing of course.

Paul Lamar

The design although not quite set in stone is at least set in foam.
  I've already started building the fuselage and wing spars.  I have a
build thread on homebuiltairplanes.com here:
http://www.homebuiltairplanes.com/forums/member-project-logs/16831-wa-1-2-spitsairwulfstang.html

  So although it hasn't been glassed yet it's still pretty much in
final form.

I had an idea that you will probably shoot down but it involves a
ovoid ejector of smaller diameter than your design and much shorter.
The screen caps will show better than words.



Above you see the ejector (made from 4" tube split in half with flat
  sides) and the intake duct.



Above shows the ejector removed so you can see the headers which
would have the swiss cheese holes in them.




And the last shows what it would look like with the cowl on. Not
shown in the pic is the cutout in the side of the fuselage.

This was very quickly roughed in just to give the general idea.  Is
this in any way feasible?

You mentioned that most people have trouble with their mufflers and
I'm wondering what they are?

Thanks,

Will Aldridge


Very ingenious ejector. Solves the motor mount problem too.

That will work of course but I doubt it will be quite enough.

The six foot coax ejector is not exactly quite. It just has a more
pleasant sound. This too may have a more pleasant sound but I doubt
it will be quiet enough.

We get lots of complaints about the noise. The six foot coax muffler
is barely acceptably quite.

Basically they melt from the 1400 t0 1700 F heat.

Paul Lamar


One additional idea I hade was to crimp the ends of the headers to make them fish tail shaped. That might conceivably cut down the noise a little more and it is almost over the wing so it might make It quieter under the plane. I know that parts melting is a problem but I was also wondering about a constricter plate at the end of the ejector?

Will Aldridge

You can do that but make the area constant and beef up the thickness of the metal
as just flattening it causes it to vibrate and fatigue.

Also extend the outer part back behind the cockpit. Beef up any long and large flat areas
with thin SS hat sections on the inside.

As you can tell we have been around and around on mufflers for the past 16 years :)

The coax muffler has been the best thing since sliced bread :)
It is the culmination of 16 years of aircraft rotary muffler experience.

Paul Lamar



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