Want to fit a 3 blade and/or a 4 blade into my P-51 MVVS 35cc combo. But Don't know what size/pitch to fit.

Any help?

Thanks

well, all I can tell you is I get 7500 with a Zinger 20-8 pro, but I hear the big Zinger's flex some. (oil, BellRay H1R 32:to1)

Jim

An 18x8 (x3) will do fine. The 35cc is a very flexible engine having a wide range of accepted loads.

Thank you gentlmen, appreciate the help

Pe,

I ran 4 tanks on the bench today, with the 20X8 prob, and Mobile1 32:1.

The tach read 6200 on full power. is this ok?

Another issue, does it mention on the manual if there is a certain way to fit the prop in (prop postion)? I can't recall if it's mentioned or not.

Thanks

RPM is in the operating range. Much depends on prop used and silencer type.
For a 2-bladed prop, the rpm are a bit low, so you seem to use a restrictive muffler.
Is the engine new? Then go easy for a while

Can you provide some more data please?

Prop is 2 bladed 20X8 Hawk (wooden). Muffler is the black box muffler by MVVS.

Tempreture was 12c , sea level. The engine is new, ran the 4 tanks on 1/3 or little less of throttle range. Did a full throttle just to check the RPM.

What is the Max. rpm for this engine, what can u get of it with box muffler.

I ordered the Bisson inverted for this engine, waiting for it to get here. wht would i expect the range of RPM with bisson muffler?


Thanks

Bisson inverted is what I have, cut a 1/2 inch or more off the stacks if they sticks way out of the cowl, this will give you more power/RPM.

Jim

The black box muffler is restrictive, It is meant to be compact, not competitive. You may gain a few hundred RPM with the bisson or the MVVS #3271, ending up in the better part of the 6000's. Any muffler made to shape of the planes nose, and with a volume over 15 times engine displacement would do as well.

For your information,

A Moki 30 turned a 20x8 prop at 5800 rpm, and so did the Supertigre 2300, both with the Krumscheid "banana" muffler. Anything above 6000 with that prop is very usable indeed.

Thank you Pe.

Pe,

I only found a mejzlik 18X10 3 blades, NOT a 18X8 as u mentioned is this ok?

Thanks

Yes, I think it would do.
The Bisson muffler compares with the 3271 type MVVS muffler. With latter muffler, and the Mejzlik 20x10 prop the engine spins at 6400 rpm (factory data), so your test with 20x8 prop and the compact muffler seems right on.
Entering these data into my trusted spreadsheet, and converting to 3-blade using E-calc's 1.97 prop power factor I expect:
with a 18x8x3 prop the engine would spin about 6800-6900 rpm, and with the 18x10x3 between 6300 and 6400 rpm static.
The 16x11x4 (4-blade, P=2.6) would also spin around 6400 rpm, if you can get such a prop somewhere. I do not know if Mejzlik will make 4-blade props to customer specification, But if you need one it would be worth a try.
All those propellers will be in the right power curve range for the 35cc engine, expect between 16 and 18lbs static thrust. This is enough to fly a 25 to 30lbs warbird in a realistic manner.
At 30 lbs your climb angle will be about 25 degrees at 45 Mph. Level top speed about 85 Mph. Stall speed 35 Mph.
At 25 lbs the climb angle will be about 35 degrees.

Thanks for the data Pe. VERY valuable.

I Think my WM P-51 GS is going to be in the 17-18 lb range with the smoke system.


Again Thanks for the help.

You're welcome.
With that weight, you will have towering to unlimited verticals.