> I don't know that a Midget Mustang would be legal--not because
it is
> single
> place but because I don't think it was ever offered in a kit as
> complete as
> the rules, that someone posted, defined. I wouldn't write off the
> aluminum
> 20B; an O-360 with an aluminum constant speed prop weighs around
> 350lb and I
> think the aluminum 20B with a turbocharger and a composite prop
> would beat
> that.
>
> It is also true that the Midget Mustang is a tough little
> airplane. What
> you have to worry about, taking it a lot faster than it was
intended,
> is
> flutter and the increased dynamic pressure. I think you will need
> additional spanwise stiffeners on the forward wings and tail
> surfaces, maybe
> a thicker windscreen, stronger landing gear fairings and a stronger
> cowl.
> There are people who can help analyze and prevent flutter. You may
> also
> need taller gear for the larger prop.
>
> This could be interesting. The reason that that Zivko Edge went so
> fast is
> that it had a GEARED O-540. They're going fast enough now that
> propellers
> are getting critical and 2.85 to 1 reduction is available for
> rotaries.
>
> Steve Brazil
>
> Steve,
>
> I agree with all of your analysis except for whether I want the
weight
> of an O-360 and a CS prop on the front of a MM. I kind of think
I don't
> want that. I'd like to shoot for O-320 weight or less in order to
> retain bad-landing survivability, and to have good span loading
and low
> trim drag. Obviously if your sense of the numbers is better
than mine,
> a 20b as you described would be the way to go.
>
> Regards,
>
> Matt-
>
> There isn't much difference in weight between the O-320 and O-360.
> It can
> be as little as ten pounds depending on variant. The big problem
> with that
> airplane is the propeller. The drawing calls out a 56 inch diameter
> prop.
>
>
http://www.mustangaero.com/images/Midget%20Mustang/Midget%203%20View.JPG
>
> <
http://www.mustangaero.com/images/Midget%20Mustang/Midget%203%20View.JPG>
>
> I think you will need a four-blade prop about 72 inches in diameter
> which
> will mean the gear will need to be another probably six inches
> taller. MT
> is probably the only supplier around for a composite prop like
that,
> the
> weight of a metal one, if there was one available, would be
prohibitive.
> Another six inches in the aft fuselage would help along with a
little
> taller
> vertical and it would still only be about 17 feet long. I think
this
> would
> work but you will have to be very careful getting used to
flying it.
> I was
> talking to my buddy today who I had helped race his RV at Reno
a few
> years
> ago and he thinks this has possibilities too. Talking about RV's it
> isn't
> the aspect ratio of the Rockets as much as it is the NACA 23014
airfoil.
> The Midget Mustang has a much faster, thinner laminar airfoil.
>
> I still think the airplane to look at is the short wing Glasair II
> RG. It's
> a nose dragger, which I don't care for, but it's easier to deal
with
> on the
> ground. It has enough room in the cowl for a turbocharged,
aluminum
> 20B and
> it was designed from scratch to use an engine of this weight.
It has
> room
> for a 72 inch propeller and you should have no problem with the
rules.
> There are also abandoned kits around that can be had for
reasonable
> money.
> One of these things with 500hp and a prop running at 2500rpm would
> be in
> the
> running. A FIXED GEAR Glasair II TD ran at better than 265 at
Reno last
> year with probably 240hp from his four-cylinder Lycoming (I
don't know
> if it
> had 390 or 400 cubic inches).
>
> Steve Brazil
>
> Steve,
> That airplane is supported by the factory. It started life as a
390,
> don't know the current displacement! I can say that it has a
hell of a
> lot more than 240 HP! 300+ as a mimimum.
> FWIW.
> Bill Jepson
>
>
> I appreciate the thoughts.. My idea was to pick the smallest proven
> airframe that could accommodate a 13b and still be a nice flying
> airplane. The 13b is great because it's possible to keep costs
down by
> using off the shelf parts, and because it's just simpler - fewer
total
> parts. Like I said in previous messages, I am interested in have
a nice
> sport plane, not some flying "manhole cover," so I think a 20b is a
> non-starter. I am not trying to discourage others from pursuing their
> own dreams, however.
>
> I had also concluded that a Midget Mustang with a 13b would need
longer
> gear for prop clearance. Before I gave up on the idea of running at
> Reno, my buddy and I were speculating on the Sport Class rules and
> whether the description of the kit to include landing gear meant
that
> the airplane actually had to use the landing gear from the kit, or
> whether substitutions could be made. If it were required to use the
> original gear, certainly extensions could be devised. My other
idea was
> to use (pieces of) the existing gear as a portion of the lower
section
> of a retractable system akin to the Grumman Bearcat - the upper
portion
> of which swings out, the lower portion swings in, kind of folding on
> itself.
>
>
http://www.warmkessel.com/jr/flying/td/jd/images/pp39_main_gear.jpg
>
> How to put retractable gear on a little airplane with a big
engine...
>
> Regards,
>
> Matt-
>
> Matt,
> The rules are pretty liberal on modifications. Daryl
Greenameyer's plane
> had large portions of the fuselage reshaped. Also the wing was
completly
> re-done. This may be one of these "old boy" deals. Before trying it
> yourself you would be best off to check with the officials and
get it in
> writing that a mod was OK!
> Bill Jepson
If you want to see what a Midget Mustang would look like cleaned up,
look at
this:
http://www.polenspecial.com/polen_special.htm
This thing actually started out as a Midget Mustang. I don't know
how much
of it is still but it shows how clean this thing can be made. It
also uses
an O-360 with a constant speed prop.
Steve Brazil
I see where they claim it has excellent auto rotation qualities.
Paul Lamar
Auto rotation??
I have been a Polen Special fan since I was a little kid - I remember
reading and re-reading the article in Sport Aviation. I also have read
that the original airplane had some kind of flutter problem with the
vertical stab, which I believe has since been fixed.
Somehow I didn't remember that the Polen was an offshoot from the Midget
Mustang, however. That is interesting.
Regards,
Matt-
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