How to make a propeller driven aircraft go really fast ?

[WonderousMountain]

Just spray the engine directly, and cool the charge.

If you go the one big engine route, I recommend X-20 arrangement.

 

[Tiger Tim]

Rv6ejguy now you’re just making me daydream about a 3/4 scale Tsunami for sport class...

 

[rv6ejguy]

Rv6ejguy now you’re just making me daydream about a 3/4 scale Tsunami for sport class...

You only live once and you can't take the money with you as they say... Don't dream- do!

 

[Speedboat100]

Risen does 312 km/h at 90 hp.

That has large wingspan...in comparison.

140 K usd.

Power to weight 0.19 hp/kg.

 

[Speedboat100]

Rv6ejguy now you’re just making me daydream about a 3/4 scale Tsunami for sport class...

It is almost possible with Mouse Merlin engine. Me-109 had 36 litre engine and Spitfire 28 litre.



Sweeping the wings and moving the wing forward and putting the gas into wings is the solution IMHO.

 

[Riggerrob]

Yes, gently swept wings help increase critical Mach number.
Many sailplanes, Formula 1 and Sport Class competitors now fly Schumann wings with elliptically curved leading edges that are gently swept. Some have straight trailing edges, but full Schumann wings have trailing edges that are slightly swept with an elliptical curve. Need composites to build gentle curves that precisely.

 

[Wild Bill]

I dont think it's trivial to get 1000hp and make it survive continuous use. Maybe if you use 2 engines. I believe the Pond Racer would qualify for sport class. It was fast enough it you could get some more reliable power in it.

The last time I followed the sport racing class, there was a requirement for the aircraft to be kit built.
Looking at the rules I found online that appears to no longer be the case.
Don’t see anything prohibiting twins..
Just the 1000 cu in limitation.

The pond racer was a cool design. Seems like I remember remember some having the opinion that aerodynamic wise it wasn’t that great.
Considering it never made the power it was supposed to, it turned some respectable speeds though.

 

[BJC]

The pond racer was a cool design. Seems like I remember remember some having the opinion that aerodynamic wise it wasn’t that great.
Considering it never made the power it was supposed to, it turned some respectable speeds though.

It is difficult (some say impossible) to have two separate engines and support structures that don’s have more drag than a single engine configuration with an engine of the same total displacement.

The Pond Racer was just another oddball design by whats-his-name.


BJC

 

[WonderousMountain]

It is difficult (some say impossible) to have two separate engines and support structures that don’s have more drag than a single engine configuration with an engine of the same total displacement.
BJC

No doubt,
.8^3 = .512 | Call it half. but frontal area = .8^2 is .64 x 2 engines. (1.28)

So if they don't go inline, or give some other advance, you're at a 5-4
disadvantage from the drawing board. Another problem with the Pond Racer was it's kinda lazy streamlining. However, the twin is proven power.

 

[Wild Bill]

It is difficult (some say impossible) to have two separate engines and support structures that don’s have more drag than a single engine configuration with an engine of the same total displacement.

The Pond Racer was just another oddball design by whats-his-name.
BJC

Yeah, 3 fuselage structures relatively close together along with all the intersections with the wing and horizontal stab seem like a deal breaker at unlimited speeds.

I’ve always wondered how a highly modified F7F would compete with the other unlimiteds at Reno.
Tigercats that I know of have been raced in a more or less stock configuration.
What would one do with a couple of R-4350’s and every speed mod possible?
I bet it would be be fast.
But that would be a 10,000 hp airplane against 3500-5000 hp airplanes.

 

[Steve C]

The Pond had only 2x 3 liter engines making probably 400hp each. They planned for 600hp, but had so many problems it never ran at full power. It hit 400 mph on course with that. It's good enough for sport class.

I had a 48lb model of the PR with relatively small motors in it. It still did over 180mph. The concern over intersection drag is way overblown. It's a fast shape and it also handled extremely well. I lost an engine on takeoff on the maiden flight. It was no problem.

 

[mcrae0104]

It is difficult (some say impossible) to have two separate engines and support structures that don’s have more drag than a single engine configuration with an engine of the same total displacement.

While I agree with this, I suspect that one of the design drivers may have been that it is easier to divide that power between two props rather than one giant one, given a small-ish airframe. Just a guess.

I'm eager to see these LS-powered contenders Ross alluded to. There have been some other weird attempts in the past...

 

[Dan Thomas]

While I agree with this, I suspect that one of the design drivers may have been that it is easier to divide that power between two props rather than one giant one, given a small-ish airframe. Just a guess.

I'm eager to see these LS-powered contenders Ross alluded to. There have been some other weird attempts in the past...

View attachment 102507View attachment 102509

Looks deadly. Wonder what it's L/D might be?

 

[Steve C]

I'm not sure if the planes he made were ever intended to fly. May have been more of a mechanical art thing.

 

[BBerson]

That co-axial thing makes no overall sense. Just put all 8 or more blades on one fan like every modern jet airliner.

 

[Dan Thomas]

I'm not sure if the planes he made were ever intended to fly. May have been more of a mechanical art thing.

Finally, some art that's worth what some folks will pay for it.

 

[Dan Thomas]

That co-axial thing makes no overall sense. Just put all 8 or more blades on one fan like every modern jet airliner.

I could see why he did the coaxial thing: to eliminate torque roll on takeoff and climb. Those short wings would have a hard time with that.

 

[BBerson]

I don't think torque is a big problem. We have RC models with enough thrust to hover vertically. The pilot hardly notices torque with a tiny bit of aileron.

 

[rbarnes]

That co-axial thing makes no overall sense. Just put all 8 or more blades on one fan like every modern jet airliner.

To put all the blades on the same hub would require the power from the two engines to be merged in a complicated transmission somehow. This way he just has a drive shaft from each engine going to each hub

 

[mcrae0104]

More info here: San Diego Air & Space Museum - Balboa Park, San Diego