How would you win the Sport Racing class/why am I wrong?

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

mm4440

Well-Known Member
Joined
Jan 14, 2012
Messages
288
Location
LA area, CA
2 big block aluminum V8's in the DO-335 configuration. Steel tube fuselage, composite flying surfaces. Gear retracts into fuselage.
Alternative based on DH 103 Hornet. pilot can bailout without the prop behind him. The 335 had one of the first ejection seats and the pilot could blow off the rear prop and vertical fin.
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
2,144
Location
Canada
My head is about half way between these two. Huge displacement V8 on the nose, tube fuselage, composite flying surfaces, shoulder wing, no fuel or other systems in the wing, gear retracts into the fuselage. I figure I’m not good enough to get it right on the first try so that basic configuration ought to give the most flexibility for modification including big stuff like shimming wing incidence or replacing flying surfaces altogether.

Basically a smaller, more refined Mr. Smoothie.
Who built the original "Mr. Smoothie?"
He looks like Steve Wittman's "Chief Oshkosh."
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
2,144
Location
Canada
Alternative based on DH 103 Hornet. pilot can bailout without the prop behind him. The 335 had one of the first ejection seats and the pilot could blow off the rear prop and vertical fin.
To further reduce profile drag, you could configure it more like a Twin Mustang or Rutan Boomerang. With only a single fuselage containing the pilot, frontal area is minimized because only one fuselage has to be wide enough to contain a cockpit..

Anything faster than 300 mph. is going to need an ejection seat, no matter what the configuration.

At those landing speeds, I prefer a nose wheel.
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
2,144
Location
Canada
Has been discussed before. 1000 cubic inch turbocharged Mountain motor in a slightly enlarged composite GP-5 type airframe, slightly swept wing. 2500hp pretty easy. Should go 550 mph on the straights.
Are you suggesting a Schumman wing like is currently fashionable among Formula 1 and sailplane competitors? Schumman wings have most of thier taper in the slightly swept leading edge. The trailing edge is straight or slightly swept.
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
9,679
Location
KWHP, Los Angeles CA, USA
The Scheumann wing planform has proven, significant gains at higher AoA and/or in turns. Since pylon racers spend slightly more than 50% of the time in banked turning flight.... it adds up.
 

rv6ejguy

Well-Known Member
HBA Supporter
Joined
Jun 26, 2012
Messages
4,560
Location
Calgary, Alberta, Canada
Are you suggesting a Schumman wing like is currently fashionable among Formula 1 and sailplane competitors? Schumman wings have most of thier taper in the slightly swept leading edge. The trailing edge is straight or slightly swept.
No, I'm suggesting ridiculously high hp in a very small airframe like a GP-5. Wing details are irrelevant when you have 3 times the hp as the fastest current competitors. :cool:

gp5.jpg
 

Toobuilder

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 19, 2010
Messages
5,283
Location
Mojave, Ca
Indeed. The Bearcat was the US military's attempt at the smallest possible airframe bolted to a big engine. Of course, it also had to carry armor and guns so its still a big airplane. But an automotive V8 can make R-2800 power at about 20% of the weight and frontal area and will fit nicely on a Lancair Legacy sized airplane, so that how to go fast. No need fo a big old boat like a Warbird to make big power. The only reason they were popular is that you could buy them for 3 grand and race the next day, not because that was the most effective way to go fast.

Essentially, it was like a demolition derby... Cheap, throw away hardware for a little fun once in a while.
 

Kyle Boatright

Well-Known Member
HBA Supporter
Joined
Nov 11, 2012
Messages
1,268
Location
Marietta, GA
Essentially, it was like a demolition derby... Cheap, throw away hardware for a little fun once in a while.
This. Right up until the throw-away hardware was all used up. The military phased out the last of the recip stuff about 40 years ago. That left some inventory of radial spares, but there is almost no ability to economically replace those stocks when they are gone.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
15,583
Location
Memphis, TN
If the surplus was not sold to the public, unlimited would still have looked like WW2 planes. The same engines would have been used, there just wouldn’t have been quite as big. 7/8 probably. No need for wells for guns or armor plating.

Those planes could take the speed off the shelf. At what speed is a Lancair or Glasair uses up its reserve of structural integrity? They were dive testing some Spitfires to 600 mph, back when they tested until stuff fell off. P-47s had a useable dive speed of 525 mph. Where do they need to go with these airframes?
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,972
Location
Thunder Bay
Who built the original "Mr. Smoothie?"
He looks like Steve Wittman's "Chief Oshkosh."
Yeah, or a much more elegant Wittman Bonzo. It’s quite late here and I’m still at work so this is off the top of my head but IIRC Mr. Smoothie was designed or built or owned by Pearson-Williams and was originally intended for an Allison engine but ended up with a Conqueror. While the landing gear was retractable it was damaged in ground transport to the races and was wired down when it was found the gear couldn’t be properly fixed with the time/facilities they had.
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
9,679
Location
KWHP, Los Angeles CA, USA
Back to the OPQ... I still believe the DO-335 layout offers advantages in frontal area, torque, no asymmetrical thrust, and lower structure weight (engine, pilot, LG, main frame masses all closer to the center).

A compressed air or mortar shell ejection seat could be fitted, or a mil surplus seat can certainly be found without an enormous effort. You'd even get an FAA approval to have a live seat in waivered airspace. However, an ejection seat would be rendered useless in the vast majority of air racing scenarios. High altitude test flying, yes of course. Pylon racing, no.

And with an inline twin engine configuration you would need two simultaneous engine failures in order to need the seat. As highly dangerous as unlimited racing is, IIRC there have actually been fairly few inflight fires that have happened, even fewer where an ejections eat would have saved the pilot.

With onboard fire bottles, modern fuel cells, and hydraulic "fuses" that shut off flow when a line is breached... it's a small slice of the pie chart where the Dornier layout would kill a pilot but a DH layout would not have.
 

Toobuilder

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 19, 2010
Messages
5,283
Location
Mojave, Ca
If the surplus was not sold to the public, unlimited would still have looked like WW2 planes. The same engines would have been used, there just wouldn’t have been quite as big. 7/8 probably. No need for wells for guns or armor plating.

Those planes could take the speed off the shelf. At what speed is a Lancair or Glasair uses up its reserve of structural integrity? They were dive testing some Spitfires to 600 mph, back when they tested until stuff fell off. P-47s had a useable dive speed of 525 mph. Where do they need to go with these airframes?
Not sure what you are getting at here... Are you suggesting that "size" determines strength? True, a Legacy is not going to 600, but thats only because its not designed to go that fast. Much easier to make a small airplane strong than a big one.
 

PMD

Well-Known Member
Joined
Apr 11, 2015
Messages
561
Location
Martensville SK
With the Otto Celera flying now, I am surprised nobody mentioned making a beefed up and shrunken 500 with enough wing to turn efficiently. It is a shame that nobody builds a 12 cylinder version of the monster v8 drag race engines. Would take a lot of prop blades to absorb 2,000+ HP, but should be do-able.
 

rv6ejguy

Well-Known Member
HBA Supporter
Joined
Jun 26, 2012
Messages
4,560
Location
Calgary, Alberta, Canada
Is a Lancair-size airframe big enough to carry the necessary fluids to cool 3000ish hp?
3000hp, no, 2000 to 2400hp probably with a liquid cooled engine as you don't need so much spray bar water as a Lyconental. The race will only be 5-6 minutes at these speeds. One wing fuel, the other spray bar water. ADI in a fuselage tank.
 

AJLiberatore

Well-Known Member
Joined
Nov 27, 2011
Messages
124
Location
Canton MI
After winning the lottery for really big $'s 🤣 4 Configs...

* Yak-3 EV w/ the YASA Motors, QS Solid-State Batteries.
* EV variant of the Pond Racer Config, Again YASA's and QS
* Slimmed down OV-10-ish w/ and Inverted V-Tail off the booms w/ 2 Highs Diesels, maybe the V12's would be too much, pick the engines that meet the max Cu In's.

A lower buck special...
* A cleaned up modernized version of the Wittman Bonzo.
* Direct Drive Big Block, insert your favorite Detroit derived V8 (V10 or 12?)
* Oh ya, fixed gear and all. IMHO it would be the crowd favorite....

I could sketch them up, it might take me a while, (Free hand not CAD)...
 

rv6ejguy

Well-Known Member
HBA Supporter
Joined
Jun 26, 2012
Messages
4,560
Location
Calgary, Alberta, Canada
The current winners are all side by side designs with more frontal area than a dedicated single seat design. The 550-580 inch, direct drive air cooled engines produce 850-900hp at best guess at around 100 inches MAP. Takeaway is that a single seat design with a modern liquid cooled, geared 750-1000 inch, 2000-2500+hp engine would be MUCH faster. The Sport Class rules have barely been tapped to date.
 
Joined
Mar 2, 2020
Messages
8
Money no object I'd consider a bespoke inline billet aluminum 6 cylinder, something like the cummins based engines that are becoming really popular in diesel truck drag racing. The inline 6 engine has decent balance characteristics if kept in the proper operating RPM, with a single rod per main throw, and big journal diameters and overlap to handle mega manifold pressure. They should be able to live all day at 60-80 PSI (not inches) of MP You'd have to do a custom spark based cylinder head, but in the grand scheme of things, it wouldn't be too difficult. I'd consider running it on straight methanol, maybe with 10%-20% nitromethane. The engine profile is right for something like a Thunder Mustang. Probably going to have to enlarge the tail surfaces to account for the P factor, and take off and land in a 3 point to get enough propeller on it to make use of the power.
 
Top