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Speed - Performance - Drag Race > r/c car engines in helis?

Mopzilla
Veteran
Location: Cupertino, CA USA

I have been thinking about this for a while. Why don't we use r/c car engines in our helis? The engines I am talking about are ones of .21 displacement, going to over 2 hp, being able to hit RPMs of up to 38,000+. I have a .30 size with the OS .32, and it only has about 1.2 HP at its max.

I believe it was a Novarossi R-1 modified used to push a SNRS4 car to over 100 mph.

These car engines use up less fuel with their lower displacement, have huge heat sink heads. Why not use them?

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Ever stop to think, and forget to start again?

06-20-2002 Over year old.

rockcrawler
Veteran
Location: Covington Wa

The modifyed drag racing helis do run the hopped up car engines,
at very high rpms.
The one I saw was a jr ergo with a .21 and tuned pipe.
The main ring gear was huge, and it sat on 40 degree angle
skids instead of level for full throttle take offs.

06-20-2002 Over year old.

Hughes500Pilot
Key Veteran
Location: Anaheim, CA

Been There, Done That

I saw 3 .21 powered drag racing helis at a fun fly a couple years back. They were geared way down to handle the 30,000 RPM's from the engine.

I'll see if I can find the photos I took and post them.

-Steve

06-20-2002 Over year old.

sweetP
Senior Heliman
Location: Sarasota,Florida

Hey hows about an OS 91 DF. Can you say flamethrower on 5%. The main gear would be huge!

What was my tag line? AMA 139721

06-21-2002 Over year old.

Mopzilla
Veteran
Location: Cupertino, CA USA

in that case.... how do you change the gear ratio in a shuttle ZXX? It seems that i can't because the placement of the engine and shaft support seem to be set...

So why not just have a super fast rotor system? maybe use smaller blades?

here are some engines:
OS .91 DF - Max Output: 4.8 BHP at 22,000 rpm

O.S. .21 RG-X (P) - Power Output: 1.9 BHP at 30,000 RPM, $180

O.S. .21 VZ-R (P) w/20K Carb - Power Output: 2.5 BHP at 34,000 RPM, $300, here is a good pic:

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Ever stop to think, and forget to start again?

06-21-2002 Over year old.

Taipan
Key Veteran
Location: Sydney, Australia

I don't know anything about car engines, but wouldn't they not last long as they're essentially being oversped? Maybe they overheat easily and/or are not reliable. I have no idea why mfrs don't use them, maybe torque is better than rpm. Also pretty much the bigger the engine, the slower it revs.

The best thing about them is they don't use fans!

As for the super fast rotor system, it would need a very strong metal r/h. I know smaller/lighter blades produce less g-forces but would be the other way round at those speeds. Plus it may put a lot of stress on the controls & would be risky/dangerous. Probably wouldn't be as stable.

The one issue of MHW showed a modified Concept with a custom made metal flapping head. Has the OS21RZR & runs a headspeed of 2200! Uses a 2 ounce fuel tank, just enough for one race.

I asked earlier if anyone has tried the 91DF & they all thought I was crazy!

Got just 1 reply. My bet it isn't very reliable. Many jets have crashed due to flame-outs.

I'm amazed how reliable the OS32 is compared to aircraft & car engines! Heli engines are very refined.

The only commercial kit is the JR Ergo CCPM Racing as shown below. There are a limited number of kits & not sure if they're still produced.
[break]

More about it here; http://www.jason.net/heli/racing.htm

06-21-2002 Over year old.

Doug
Elite Veteran
Location: Naples Florida....

would be ok for short periods. In cars they only use full power for short periods. To pull even 1 hp continious for 10 min, I think the engine will be in trouble.

06-21-2002 Over year old.

slant911
Veteran
Location: Las Vegas, NV. Hirobo, Magnum Fuels, MAH

There is a guy out at my field that took a JR Voyager (Electric Heli) and put a .12 size car engine in it. Ater a lot of tinkering with it and gearing and such he got it to fly pretty darn good. The problem ended up being that the plastic parts in the head were not meant to take that sort of stress and ultimately failed in flight. Last I heard from him he was rebuilding it with a different head (metal) and other upgraded parts. It was very cool to see it fly.

06-21-2002 Over year old.

HOMEPAGE

Mopzilla
Veteran
Location: Cupertino, CA USA

Just for the record, what is the average RPM of the OS .32SXH in a hover?

Max RPM as listed is 22k. 1.2hp at 18k. DF engine, however, also gives 25k rpm, but listed at 4.8 HP at 22k rpm..... I like!!!!

but for $320, i dunno... just add $500 and i can get a fury...

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Ever stop to think, and forget to start again?

06-21-2002 Over year old.

slant911
Veteran
Location: Las Vegas, NV. Hirobo, Magnum Fuels, MAH

I think the Os .32 goes about 16000 to 17000 RPM's. Somewhere in that neighborhood.

06-21-2002 Over year old.

HOMEPAGE

baby_zyklon
Key Veteran
Location: Singapore

I don't think the a car engine especially a .21 size will last long in a heli , because they run to a very high temp even when in a car where the throttle push and release, so I think in a 3d heli the engine will be overheated in last then 2 flights. Also car engines are not as tolerance to heat as heli(that explain the big heat), one extremely hot run of 5min will definately ruin the engine.

#61 on the 700N list and Proud of it.

06-22-2002 Over year old.

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volare
Veteran
Location: Cincinnati Area

Get yourself a radiator and overheating may not be a problem, right Mop?

06-23-2002 Over year old.

Mark Ryder
Administrator
Location: Encino, CA

06-23-2002 Over year old.

HOMEPAGE

Mopzilla
Veteran
Location: Cupertino, CA USA

mark - looks like one of the OS RZ engines?

Anybody know if i can still buy that kit somewhere?

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Ever stop to think, and forget to start again?

06-23-2002 Over year old.

Ooppss
Senior Heliman
Location: At the field flying !!

01-18-2003 Over year old.

w.pasman
Elite Veteran
Location: Netherlands

I heard that those car engines should not be run at full power for more than 5 seconds. For cars that's not a problem as you'll be at the next turn anyway after 3 seconds. But for helis that's different.

01-19-2003 Over year old.

HOMEPAGE

Mopzilla
Veteran
Location: Cupertino, CA USA

It is fine to run these car engines at top speed for more than 5 seconds, in fact I have done it all the time in one of my r/c cars, and they went very fast and well... the engine lasted about 1 gallon though.. they only do last 1-3 gallons depending on how much you run it.

They are very good fast engines

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Ever stop to think, and forget to start again?

01-21-2003 Over year old.

ScottH
Senior Heliman
Location: Long Beach, Ca.

Heli engines are designed for more torque. HP is just a formula, showing work. The higher the rpm, the higher the HP for a constant torque. The .21 car engines have impressive HP numbers due to their high rpm, but their powerband is very narrow. Heli's need a wide torque curve to hold headspeed throughout the pitch range. That, and some serious gearing is required at 30,000 rpm that a car engine spins....
Scott

01-21-2003 Over year old.

chrtir
Heliman
Location: Ramstein AB Germany

i would have to agree with scott

01-21-2003 Over year old.

Lwnemesis
Senior Heliman
Location: Seattle, WA

Scott, is correct. Its not the HP that turns our rotors is the Torque. All those tiny engines would not be able to cope with the load.

01-23-2003 Over year old.

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Speed - Performance - Drag Race > r/c car engines in helis?

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