Somebody, please break Mach in the Reno Unlimited Class

[ilyan]

There is no technological reason why a piston engine propeller plane cannot break Mach, and the best place to do it and get everyone's attention is the Reno Unlimited Class.

Please see the article in Popular Science regarding David Rose and his supersonic piston engine prop job called Renegade. Here is the link:

http://www.popsci.com/military-aviation-space/article/2004-08/win-reno-go-supersonic#comment-128312

I've got my own ideas about a supersonic propeller plane with a piston engine. I want to use a Dyna-Cam piston engine, also called an Axial Vector Engine, produced by the Axial Vector Energy Corporation (AVEC).

I can't afford the equipment, nor do I have the skills needed to carry out such a project, but I know there are those of you out there who have the resources and the skills. I have a conceptual understanding, but I have no way to realize the idea.

[AirDOGGe]

Re: Somebody, please break Mach in the Reno Unlimited Class

There is no technological reason why a piston engine propeller plane cannot break Mach

There isn't? Yes there is.

For a propeller-driven aircraft to go the speed of sound, the propeller blades would have to be going FASTER than the speed of sound, correct?

That's where the whole tech-fail thing comes in. When propeller blades go supersonic, they LOSE efficiency. The plane slows down instead of going faster.

The experts already went down this road decades ago with the XF-84H. All that propeller did well was make lots of noise.

Please see the article in Popular Science regarding David Rose and his supersonic piston engine prop job called Renegade.

As far as Dave's wicked-looking bird goes, go back and note the date on the article. It's going on 8 years old.

The photos you see on the internet are even older, and I don't think the airframe has flown even as of today, much less attained any form of maximum airspeed to back up claims of supersonic or even near-transonic capability.. I can't find any NEW data or updates on the plane or dual powerplants in any form. Anyone?



And finally, concerning setting a supersonic speed at Stead (besides being illegal by federal law), you'd probably want some sort of straight-line course for maximum speed records of that magnitude, and because of said law, it would have to be over water.

Turning slows you down, and Stead's track is tight enough as it is at 500mph speeds. Besides, think of all those expensive broken windows in neighboring houses.

.

[ilyan]

Re: Somebody, please break Mach in the Reno Unlimited Class

A propeller blade is an airfoil, just like a wing. If you use the proper airfoil and apply enough power to keep it supersonic, it will generate lift, or thrust in the case of a propeller. The fan blade tips on a Boeing-777 at full power are supersonic. That fan is nothing more than a 21-blade propeller with a duct around it.

Of course, a blade tip being supersonic is not the same as the entire blade being supersonic, but again, a prop blade is like a wing. You can force the whole blade to go supersonic. If you apply enough power to spin it at sufficiently high RPM, it will generate thrust, and lots of it. All it takes is brute power, and that's what this type of project is all about.

The age old aviation cliché fits perfectly here: You can make a barn door fly if you give it enough power.

Is this efficient? No. That's not the issue here. Neither is noise. Reno fans like noise.

Is it possible? Yes. That's the task at hand.

True, Renegade never flew in the 2005 Reno Unlimited Class as it was intended to do. But that doesn't mean it would have failed. Somebody just decided not to pursue the project after the rules changed. Renegade was intended to be a purpose-built aircraft, designed specifically to be raced at just above Mach 1. Apparently, the Reno Air Race Association decided to change the rules so Renegade would not be allowed to race, and the project had no more purpose. See my blog article on the subject at http://earthsink.blogspot.com/

There must be at least one enthusiast out there who wants to resurrect such a project simply for the pure thrill of going supersonic with a piston engine and a propeller. I would do it without hesitation. I just don't have the money or the aircraft fabrication skills to realize such a goal.

Maybe I'm the only guy on the planet who feels the urge to design, build, and pilot a supersonic, piston engine, propeller driven airplane. I don't care whether or not I get to race it. I don't care if the whole idea sounds silly and absurd. I just want to do it.

[First time Juke]

Re: Somebody, please break Mach in the Reno Unlimited Class

Then I have a kite for you.

It is a bit noseheavy , but can be corrected. I know John Roncz..we could come up with a right set up for it.

Radiators are on top of the engines ( not drawn, secret until yesterday ).

It has got all you need..supersonic aerodynamics and insane power to weight ratio.

[ilyan]

Re: Somebody, please break Mach in the Reno Unlimited Class

Thanks for the link. Awesome designs!

http://earthsink.blogspot.com

[First time Juke]

Re: Somebody, please break Mach in the Reno Unlimited Class

The lighter axial engine possibly could have solved the noseheavy issue as well on my design.
Are you more of an author type and not really an air racer at any level ( R/C perhaps a little ) ?

[ilyan]

Re: Somebody, please break Mach in the Reno Unlimited Class

I am more of an author by trade, but more of a pilot at heart. Due to lack of resources and lack of formal engineering skills, I am limited to using my conceptual imagination for the foreseeable future.

I have a private pilot license and an instrument rating, but I have not flown for over 20 years. However, I keep my mind active and my hope bright that someday I will again log abundant hours of flight time, and most of those hours will hopefully be in aircraft of my own design, and hopefully some of those hours will be at Stead Field in the Unlimited Class.

In the mean time, if anything I write happens to inspire someone with the right skills and resources to realize a daring idea or a controversial project then my efforts are well spent.

http://earthsink.blogspot.com

[First time Juke]

Re: Somebody, please break Mach in the Reno Unlimited Class

http://www.engineeringtv.com/video/AVEC-Axial-Vector-Engine

AVEC engine once more...a new vid.

[ilyan]

Re: Somebody, please break Mach in the Reno Unlimited Class

Thanks for the link. Very interesting. Gotta love those low-friction silicon-nitrate bearings. So hard it takes diamond to cut and polish them, and they are less than a third the weight of an equal size steel bearing. No cylinder wall side loading is nice, too. Notice how small the pistons are, and there are no piston rings.

I would like to learn more about the new "motion-to-power" thermodynamic cycle that Douglas Hahn, AVEC's Chief Engineer mentioned in the video.

All I can say is, I want one!

http://earthsink.blogspot.com

[AirDOGGe]

Re: Somebody, please break Mach in the Reno Unlimited Class

A propeller blade is an airfoil, just like a wing. If you use the proper airfoil and apply enough power to keep it supersonic, it will generate lift, or thrust in the case of a propeller. The fan blade tips on a Boeing-777 at full power are supersonic. That fan is nothing more than a 21-blade propeller with a duct around it.

Of course, a blade tip being supersonic is not the same as the entire blade being supersonic, but again, a prop blade is like a wing. You can force the whole blade to go supersonic. If you apply enough power to spin it at sufficiently high RPM, it will generate thrust, and lots of it. All it takes is brute power, and that's what this type of project is all about.

The age old aviation cliché fits perfectly here: You can make a barn door fly if you give it enough power.

Is this efficient? No. That's not the issue here. Neither is noise. Reno fans like noise.

Is it possible? Yes. That's the task at hand.

True, Renegade never flew in the 2005 Reno Unlimited Class as it was intended to do. But that doesn't mean it would have failed. Somebody just decided not to pursue the project after the rules changed. Renegade was intended to be a purpose-built aircraft, designed specifically to be raced at just above Mach 1. Apparently, the Reno Air Race Association decided to change the rules so Renegade would not be allowed to race, and the project had no more purpose. See my blog article on the subject at http://earthsink.blogspot.com/

There must be at least one enthusiast out there who wants to resurrect such a project simply for the pure thrill of going supersonic with a piston engine and a propeller. I would do it without hesitation. I just don't have the money or the aircraft fabrication skills to realize such a goal.

Maybe I'm the only guy on the planet who feels the urge to design, build, and pilot a supersonic, piston engine, propeller driven airplane. I don't care whether or not I get to race it. I don't care if the whole idea sounds silly and absurd. I just want to do it.

"A propeller blade is an airfoil, just like a wing. "

Similar to a wing, yes, but not a wing. While a blade rotates forward through the air leading-edge-first like a wing, it's flight path is perpendicular to that path. The environment is quite different. That's why the best wing shape and airfoil profile is not directly applicable to a propeller, which may work better with a completely different profile.

Apples may be round like oranges and bear on fruit trees like oranges and are good to eat like oranges, but they aren't oranges.



The shockwaves themselves coming off the blades and striking the wings and airframe may cause issues and will have to be dealt with. Supersonic aircraft can fly ahead of their shockwaves and the drag and disturbances they cause, but an aircraft in front of a supersonic prop can't escape the latter's "thunder". Rotating sonic booms (The gut-wretching SCREECH in "XF-84H THUNDERSCREECH") in front of any aircraft/pilot gives me pause for thought.


(The shockwaves of supersonic propeller TIPS like those on the T-6 Texan are mild in comparison and don't really apply to this discussion).


Even though interest in supersonic propellers was lost to the jet age, there was quite a bit of research done, and the Soviets continued propeller research far longer, yet nobody came up with a usable Mach1+ propeller and still hasn't to this day.


Perhaps someone soon will find an answer, but not like this. The NACA and others had expensive tools, computers and the best engineers on the project, and NASA and it's peers plus other modern professional designers have a great amount of previously-attained knowledge to draw from and MUCH faster computers to work with today, so if an answer is found, I expect it to come from one of them.


What chance does a small-scale experimental aircraft builder have? This isn't rocket science, but it's not far from it. It could even be harder than the latter at this point of development.

I'll rate the chances of even a builder of Rutan's level of producing a successful supersonic propeller as "Possible, but not probable".


.

[First time Juke]

Re: Somebody, please break Mach in the Reno Unlimited Class

XF5U "the flying pancake" possibly could have gone supersonic if the aerodynamics were tuned for it, but they weren't.

[mrcraigarcher]

Re: Somebody, please break Mach in the Reno Unlimited Class

(The shockwaves of supersonic propeller TIPS like those on the T-6 Texan are mild in comparison and don't really apply to this discussion).

Is this why the T-6s are so loud? (newbie question)

Craig

[AAFO_WSagar]

Re: Somebody, please break Mach in the Reno Unlimited Class

Is this why the T-6s are so loud? (newbie question)

Craig

Yes and it's the same reason that when you're up in places like the San Juans, you will hear the tips of seaplanes off in the distance on takeoff.... wonderful sound if ya asske me!!

[AirDOGGe]

Re: Somebody, please break Mach in the Reno Unlimited Class

XF5U "the flying pancake" possibly could have gone supersonic if the aerodynamics were tuned for it, but they weren't.

Put a big enough jet or rocket engine on it and you could make almost anything go supersonic, assuming the item seeking high-speed flight can withstand the stresses and forces. Stability would be an issue though


.

But either way, please take note that a propeller with blades traveling through the air faster than sound waves doesn't mean an aircraft sporting them would do likewise. I don't know if one could, but I don't think so, due to loss of propeller efficiency in the aircraft's transonic region. Surely someone in some nation would have done it by now if it were possible.

Just the thought of the shockwaves from the spinning blades encountering and interacting with the shockwave(s) produced from the plane's forward momentum as it approaches transonic speeds is mind-boggling!


Even today such "Sonic-props" are being studied, and may exist in some form eventually, but nobody is talking about breaking the sound barrier with one. They are just seeking greater efficiency.

[AirDOGGe]

Re: Somebody, please break Mach in the Reno Unlimited Class

I just stumbled across what appears to be the most informative article yet I have read on the XF-84H.

http://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=821

It state as that the idea behind the supersonic propeller was to create a fighter aircraft as fast as a standard F-84 jet, but with the range of a propeller-driven fighter, not to break the sound barrier with it.