Somebody, please break Mach in the Reno Unlimited Class

[First time Juke]

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.

XF-84 did brake the sound barrier.

[bellarch]

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

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....

my $0.02

[AirDOGGe]

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

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) 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]

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

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) 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]

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

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)

[AirDOGGe]

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

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:





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:





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]

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

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]

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

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]

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

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) . 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).

[Lockheed Bob]

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

YeahAirDOGGE .I wouldn't want that setup running between my legs.

[First time Juke]

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

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 ?

[John]

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

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.

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

[AirDOGGe]

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

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...). 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.

[AirDOGGe]

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

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.)


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