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View Full Version : Somebody, please break Mach in the Reno Unlimited Class



ilyan
12-29-2011, 09:30 AM
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.

:1zhelp:

AirDOGGe
12-29-2011, 04:16 PM
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 (http://en.wikipedia.org/wiki/Republic_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
12-29-2011, 04:57 PM
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.

:thumbsup:

First time Juke
01-02-2012, 12:59 PM
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
01-03-2012, 09:18 AM
Thanks for the link. Awesome designs!
:thumbsup:


http://earthsink.blogspot.com

First time Juke
01-04-2012, 02:40 AM
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
01-04-2012, 08:32 PM
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.
:thumbsup:

http://earthsink.blogspot.com

First time Juke
01-05-2012, 05:54 AM
http://www.engineeringtv.com/video/AVEC-Axial-Vector-Engine

AVEC engine once more...a new vid.

ilyan
01-05-2012, 09:12 AM
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!
:D


http://earthsink.blogspot.com

AirDOGGe
01-17-2012, 07:17 PM
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.

:thumbsup:


"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
01-18-2012, 08:31 AM
XF5U "the flying pancake" possibly could have gone supersonic if the aerodynamics were tuned for it, but they weren't.

mrcraigarcher
01-18-2012, 08:36 AM
(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
01-18-2012, 10:52 AM
Is this why the T-6s are so loud? (newbie question)

CraigYes 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
01-19-2012, 10:01 AM
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
01-30-2012, 11:49 PM
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.

First time Juke
02-02-2012, 09:21 AM
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.

XF-84 did brake the sound barrier.

bellarch
02-02-2012, 10:05 AM
From the absolutely mistake-free Wikipedia...
"The Tupolev Tu-95 (BEAR) is a large, four-engine turboprop-powered strategic bomber and missile platform. The aircraft has four Kuznetsov NK-12 engines, each driving contra-rotating propellers. An airliner variant Tu-114 holds the record as the world's fastest propeller-driven aircraft. Some experimental aircraft were designed for theoretically higher speeds, but none attained or registered them........ Its blades, which rotate faster than the speed of sound, according to one media source, make it arguably the noisiest military aircraft on earth,[2] with only the experimental 1950s era Republic XF-84H "Thunderscreech" turboprop powered American fighter design as a likely rival."

575mph was the "Record"

Let's add this up:

1. Contra-rotating props MAY help cancel-out, or mitigate efficiency losses.
2. Name your aircraft "BEAR" and of course records will be broken!

Question: Has there ever been a contra-prop fitted to a radial?

When Navy and Air Force pilots politely "shadowed" the bears during the cold war, there were zones pilots did not drift into due to the sonic harmonics...allegedly....:cool:

my $0.02

AirDOGGe
02-07-2012, 08:47 PM
XF-84 did brake the sound barrier.


There was no "XF-84", and the XF-84H certainly never went that fast, although it's prop blades did. Read the details in the article I posted above.


The jet-thrust-only F-84 prototypes were called "XP-84" and "YP-84A". They don't apply here, as neither had a propeller of any type.







Question: Has there ever been a contra-prop fitted to a radial?



I know one of the two experimental Lycoming XP-7755 radials (36 cylinders) (http://en.wikipedia.org/wiki/Lycoming_XR-7755) had coaxial splined prop shafts for such a dual-prop set-up. That's the engine Howard Hughes originally planned on using when designing the Spruce Goose, the engine's cancellation forcing him to use smaller P&W 4360's instead.


And speaking of that eccentric "rich guy" and those famous corncob Pratts, his experimental XF-11 twin-boom fighter that he crashed and almost died in had counter-rotating props mounted on it's 4360s.


That's all I know of on this side of the Atlantic.


.

First time Juke
02-10-2012, 01:51 PM
There was no "XF-84", and the XF-84H certainly never went that fast, although it's prop blades did. Read the details in the article I posted above.


The jet-thrust-only F-84 prototypes were called "XP-84" and "YP-84A". They don't apply here, as neither had a propeller of any type.








I know one of the two experimental Lycoming XP-7755 radials (36 cylinders) (http://en.wikipedia.org/wiki/Lycoming_XR-7755) had coaxial splined prop shafts for such a dual-prop set-up. That's the engine Howard Hughes originally planned on using when designing the Spruce Goose, the engine's cancellation forcing him to use smaller P&W 4360's instead.


And speaking of that eccentric "rich guy" and those famous corncob Pratts, his experimental XF-11 twin-boom fighter that he crashed and almost died in had counter-rotating props mounted on it's 4360s.


That's all I know of on this side of the Atlantic.


.

I actually was in e-mail ex-change with the pilot who flew the prop version supersonic...really nice gentleman and an american hero of course.

I doubt the supersonic needs a 5000 hp engine. It needs good clean aerodynamics and an excellent power to weight ratio.

But if you insist 5000 hp then this !

Lockheed Bob
02-10-2012, 08:46 PM
Going back to the question of dual-rotation radial. The original Curtis XP62 had a Wright 3350 with that setup but it never went into production. The Fisher (GM) XP75 had a Allison V-3420-19 with dual-rotation & that didn't go into production either. Pictures of both are in a book called U.S. Fighters by Lloyd S. Jones (Army-Airforce 1925 to 1980s) :beerchug:

AirDOGGe
02-11-2012, 01:38 PM
Actually the Allison (basically two V-12s, not a radial) had dual side-by-side output drive-shafts that led to a remote gearbox with the contra-prop shafts., like this:

http://airpigz.com/storage/2010-september/reno-2010/Allison_V-3420_Front.jpg?__SQUARESPACE_CACHEVERSION=12847634 48260



I don't think I've seen one with a coaxial gearbox and prop shafts actually mounted on the engine. The 3420's that I've seen were all single output, like this:

http://farm4.static.flickr.com/3519/4082262846_82ac4fa2ed.jpg



If you know of one with contra props mounted to the engine itself, please inform me. That would be an interesting item to know of.




I actually was in e-mail ex-change with the pilot who flew the prop version supersonic...really nice gentleman and an american hero of course.


Well, forgive me if I dis-believe you, but that statement goes against every aviation book and article I have ever read on the topic of the XF-84H. Can you verify it somehow?

What was the name of this "hero"? If you corresponded with him then surely you remember who he was.


.

Lockheed Bob
02-11-2012, 03:35 PM
AirDOGGE,The photos of the XP75 that first flew on Nov.17,1943 had the Allison-3420-19 driving contra-rotating props via an extension shaft. Plane by Fisher (GM) was flown at Cleveland airport & I did get to see it being tested including an in-flight fire in which the test pilot was killed.

W J Pearce
02-11-2012, 06:29 PM
OK, sorry but I have not really read all the posts on this thread. I'm sorry for posting with out actually reading each and every word but, well, I'm lazy. Sorry in advance if I am providing information that is not relevant.

Regarding the XF-84H, it is my understanding the the top speed was estimated to be 520 mph but the aircraft never achieved anything near that. But the props were supersonic.

Regarding contra props on radials. Yes, R-1830, R-2800, R-3350, R-4360 all had CR versions. In addition, the, Mitsubishi MK4D Kasei 14, Mitsubishi MK4S Kasei 14, Nakajima Ha-109, BMW 802 (I think but maybe not), BMW 803, Lycoming XR-7755, and Wright XR-2160 all had CR versions.

I can not think of any British or Russian CR radials. The Bristol Brabazon had two Centaurus engines, each driving a set of propellers so the engines were not really CR but the aircraft was.

I am not aware of any Allison 3420s with the CR box mounted to the engine. Obviously there were CR versions done through shafts like the XP-75.

AirDOGGe
02-11-2012, 07:48 PM
AirDOGGE,The photos of the XP75 that first flew on Nov.17,1943 had the Allison-3420-19 driving contra-rotating props via an extension shaft.


That's the engine seen in the top photo of my last post, although according to the Smithsonian Air & Space museum, it's a Allison V-3420-23 (V-3420-B10) (http://www.enginehistory.org/Museums/nasm.shtml) . It had 2 opposite-turning shafts running to a nose-mounted gearbox supporting the contra props. Personally, I couldn't tell a dash-19 from a dash-whatever-you-got.

Here's another photo of the version the XP-75 used (too big to display, CLICK HERE TO VIEW) (http://www.enginehistory.org/Gallery/JimBuckel/Allison%20V-3420%20for%20Fisher%20P-75A%20Eagle%201-17.JPG).

Lockheed Bob
02-11-2012, 08:35 PM
YeahAirDOGGE .I wouldn't want that setup running between my legs.:beerchug:

First time Juke
02-17-2012, 10:35 AM
I am just wondering when I counted/estimated ( by adding all bits and pieces together ) the weight for my really lite endurance AC design with a wing half weight of about 25 lbs ( with landing apparatus )...that couldn't the mach come faster at you when you increase the power to weight ratio / thrust to weight ratio by making the weight go down instead of just look for an enermous engine for it ?
:dunno:

John
03-10-2012, 11:33 AM
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.

:1zhelp:

Look up: XF-88B (Voodoo). Apparently it has been done, but with jet engines and jet assist.

AirDOGGe
03-16-2012, 10:41 PM
Look up: XF-88B (Voodoo). Apparently it has been done, but with jet engines and jet assist.


Exactly, and that's one big "but" (fortunately, AirDOGGe LIKES big butts...:rolleyes:). While sporting a prop for supersonic propeller research, the B model didn't go supersonic on prop-power alone.


According to one description:

Probably the fastest aircraft ever fitted with an operating propeller was the experimental McDonnell XF-88B, which was made by installing an Allison T38 turboshaft engine in the nose of a pure jet-powered XF-88 Voodoo.

This unusual aircraft was intended to explore the use of high-speed propellers and achieved supersonic speeds. This aircraft is not considered to be propeller-driven since most of the thrust was provided by two jet engines.


The XF-88B is basically a jet airplane that had a turboprop grafted on the nose later in life for research purposes. It's not a prop-driven supersonic aircraft as the XF-84H was intended to be.


Note that in nearly every photo of the former in flight I can find on the 'net the prop is shown feathered, like these samples shown below. That's an interesting point-of-observation right there, although admittedly it doesn't prove anything.


http://img831.imageshack.us/img831/574/xf88b001voodoo.jpg

AirDOGGe
03-18-2012, 12:47 PM
If interested, here's some real video of the XF-88B in action. it includes footage with the plane sporting a 3-bladed propeller that is possibly the one that was eventually mounted on the propeller-driven-only XF-84H.

( I believe I read somewhere that the latter's supersonic prop was first tested on this jet-propelled aircraft.)


http://www.youtube.com/watch?v=l1rqlfhLdvc