> Hey Paul,
>
> I have seen a number of Midget Mustangs (the single seater)
powered by
> O-320's. I just saw an MM powered by an O-360 with a C/S
prop. I'd
> have to think it would be fairly reasonable to stuff a
13B into
an MM.
> Maybe even mount the radiator under/behind the pilot, just
like the
> P-51. Could help the weight and balance. I've also seen a
couple of
> MM's with retractable landing gear. Such a combination
should
qualify
> for Sport Class - enough have been built. I'd like to
have a
structural
> analysis for flutter. It shouldn't be against class rules
to put
enough
> more beef in the structure to make it go
400mph.. Hah. :) Or
at least
> fast enough to raise some eyebrows.
>
>
> Regards
>
> Matt-
If you want to run in the Sport Class with a Midget
Mustang, I
would
use an
aluminum 20B. A better place for the radiators is in the
inboard
leading
edges. I think this is actually a lower drag installation and
you won't
have to sit on those coolant lines.
Steve Brazil
Rather than an Al 20b, I'd go with a turbocharged aluminum 13b. It
would fit better, and probably fly better, and be plenty of
horsepower.
I see a development path on the airframe starting with an O-200
(I have
one), moving to an NA P-Port Iron 13b, and then to turbocharged
Al (if
I'm still having fun).. I realize there's no replacement for
displacement however.
Thanks,
Matt-
You know Matt there are plenty of cheap Formula 1 airplanes for
sale.
Here is the slickest one I have seen so far. Not necessarily
for sale.
Paul Lamar
That's a Mike Arnold designed airplane Paul (the Endeavor - AR-6). Mr
Arnold came to fame as a film maker turned airplane designer who built a
65hp Rotax powered airplane that ran ~215mph on a timed course -
setting
a world record, and earning the claim to being the only (or one of few)
man carrying powered airplanes with a flat plate drag equivalent of less
than 1 sq ft. Mr. Arnold studied and applied Hoerner's works
extensively in the AR-5, and then again in Dave Hoover's Endeavor. A
talented guy.
I suspect that the AR-6 is actually a nice flying airplane, unlike most
of the F1 birds. In a conversation I had with Gary Hubler a few years
ago, I got the impression that Mariah (a heavily modified Cassutt)
actually didn't fly particularly well - on the first flight he was doing
aerobatics - a loop required forward stick pressure all the way around.
They put lead in the prop extension/spinner to try to get the CG more
reasonable. Most of the fast f1 airplanes have really thin airfoil
sections and tiny control surfaces. Eeesh.
The MM's are too big to be competitive in F1 racing (IMO), but if you
put more hp on them they could be pretty fast. They have conventional
Aluminum construction which should make structural analysis and
improvement easier. The MM is already pretty strong - being rated at
something around 9g ultimate and having a 230mph published VNE.
Obviously a study would be required to see what the limitation on VNE is
and how to increase it.
I would prefer to keep the overall airframe weight close to the stock MM
max takeoff weight (at odds with the above goal).. At that weight the
MM has a reasonable stall speed (~60mph). The stall speed has the
largest effect on bad-landing (off airport) survivability. It's _much_
easier to provide impact protection for 60mph than for 90mph. I am not
a daredevil nor a fighter pilot, and so I would like whatever I come up
with to remain a nice sport airplane.. My goal isn't to actually win at
Reno, but to have something that I could fly to the races, raise a few
eyebrows, and have well less than $50k in (total). It would be fun to
be able to spank a few F1 rockets and slower Lancairs too.
Regards,
Matt-
I totally agree on the stall speed. The energy in a crash is m*V^2.
Fowler flaps can triple the landing lift coefficient required so if
you want
to go fast and keep 60 MPH stall speed you need just enough wing
area to have
a stall speed of 60 MPH with the flaps out. The other mandatory
requirement for
going fast at Reno is a high aspect ratio wing. AKA low span loading
as you are
in a continuous turn almost. Induced drag is Cl^2/(pi*A). 2G turn
twice the Cl.
Three G turn 3 times the Cl. Four times as much induced drag at only
a 2 G turn.
All of this assumes you keep the weight as low as possible.
I don't think a single place qualifies for Sport Aircraft at Reno.
That I think is why they put the pax sort of next to the pilot
in the Nemesis Nxt.
--
Paul Lamar ...No rotor no motor.
The Sport Class rules:
A. Aircraft eligible for competition within the Sport Class shall fall
into either of two catagories: Sport or Super Sport. Sport aircraft
shall be limited to production model kit-built aircraft, to include
Long and Vari Eze models, of which 5 or more kits have been produced
and delivered to customers by the manufacturer, powered by a
reciprocating engine of 650 cu in. or less, and capable of a 200 MPH
qualification lap speed. Super Sport aircraft shall be limited to
production model kit-built aircraft, of which 5 or more kits have been
produced and delivered to customers by the manufacturer, powered by a
reciprocating engine of 1000 cu in. or less, and capable of a 300 MPH
qualification lap speed. A kit is herein defined as consisting of
wings, empenage, fuselage and all related control surfaces. Also
included must be landing gear, canopy, motor mount and sufficient
build instructions. The prototype may be included as one of the 5
required kits. The specifications listed herein will be the only
specifications of the Sport Class. Aircraft not in compliance will be
disqualified from the competition. The Sport Class Board of Directors
will implement disqualification upon due consideration along with
recommendation of the Technical Committee and/or the Contest
Committee. Any significant airframe modifications to eligible kit
built aircraft must be approved by the Pilot Standards/Committee prior
to entry.
My interpretation of this would allow running a single seat MM in Sport
Class... There was a single seat Harmon Rocket and I think a single
seat Edge 540T a few years ago (the Rocket was surprisingly slow, and
the Edge was surprisingly fast).
I think they made the NXT a 1.5 seater for marketing considerations, and
possibly for aerodynamics (area rule). I understand that some future
NXT's might be narrowed to a true single seater.
Regards,
Matt-
OK I stand corrected. Looks like an RV3 also qualifies.
Of course the wing is too short to be competive. That is why the Rockets
are so slow and why the Edge is so fast. What is the wing span on the MM?
Paul Lamar ...No rotor no motor.
Paul,
Of course one of the other considerations is how much motor you can
stuff in there. Looking at the NXT with the cowl off ther isn't a lot of
room to make the engine compartment narrower. With the turbos, and the
intercoolers there is just very little room in there. A 20B would fit in
a single though! The lyc wouldn't allow a much smaller package!
Bill Jepson
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
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.