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Old Nov 15, 2012, 01:07 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
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FWIW.... Heli engines these days are turning around 17000 RPM.

One mans opinion.... Mine I think in the end, you would be far happier with a belt reduction drive. You won't have to have the engine scream at 17,000 RPM. The heli drive will also let the prop windmill while not under power due to the auto rotation clutch. Maybe this is something you planned on???? "Gear" belts and pullyes are readily available and making a drive would not be to hard. E-bay might cough up an old Byron drive also.

You have quite the project there. Keep us in the loop!

Ken
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Old Nov 15, 2012, 02:00 PM
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United States, MD, Elkton
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Thanks,Ken-you are PART of the loop !
I don't believe I need a lot of rpms-I flew a 1/3 Scale Sopwith Pup (9') with this prop at a cruise of about 3,000 r's..No way I need that performance on this low wing loading rubber powered free flight model...I will allow as I might need 1500 to 1700,but I don't think so.
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Old Nov 15, 2012, 04:46 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
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I was just thinking..... It you wanted to keep the windmill of the heli drive but want belt drive, all you have to do is add a one way bearing to the driven pulley.

Ken
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Old Nov 15, 2012, 05:18 PM
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So...this is a home built, re-engineered free flight helicopter with a 40 inch rotor? Aside from the fact that I'm very glad I live a long way from Iowa, the "glide" descent of this craft may be more rapid than you anticipate. Small models bounce where large ones crash (spectacularly). Just food for thought.
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Old Nov 15, 2012, 08:24 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
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I thought it was and it is.......

That is an old GMP (Goram Model Products) heli frame. I have what's left of a Cobra converted to a 60. Not bad helis for the day. They used a lot of Hirobo parts. The clutch set up on those can be a tad problematic. You had to shim the clutch with .001 shim stock to get zero run out on the start shaft. That and possibly shim it sideways if you got a "bad one" from the factory. If you had a good one and spent a lot of time, like we did back in the day, it will run smooth. Just be prepared if it doesn't..... Mine had ball bearings (some were brass bushings) in the pinion gear that needed to be serviced periodically. It will be a pain to do that with the setup you have there. You have to pull the engine out of the frame to do it. It was bad enough on a heli. It will be worse on your set up.

Now that I see that, I would steer away from that particular setup.

Ken
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Old Nov 16, 2012, 03:39 AM
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Quote:
Originally Posted by Gnu4FF View Post
So...this is a home built, re-engineered free flight helicopter with a 40 inch rotor? Aside from the fact that I'm very glad I live a long way from Iowa, the "glide" descent of this craft may be more rapid than you anticipate. Small models bounce where large ones crash (spectacularly). Just food for thought.
Maybe you didn't read post #11,or at least look at the pictures.This is not a helicopter.We are using a helicopter DRIVE system to power a vintage model airplane with a flight speed of a jogger-just for fun....
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Old Nov 16, 2012, 04:24 AM
Complete RC Idiot Savant
The Netherlands
Joined Nov 2009
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But it is intended as a free flight model, yes?

Can't think of a reason, not to install radio gear and just enjoy it flying a little bit longer and a little bit more controlled....

Brgds, Bert
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Old Nov 16, 2012, 06:33 AM
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Oh -no Bert ! It's R/C..I'm sorry I didn't clarify that...Much too safety concious to allow something this big to wander around freely.
My intention is to build a large model representing a 32" original.
I've been considering ailerons as part of the wing construction,as well.
Things are progressing nicely,but I'm having difficulty conveying my point.It seems folks pick up in the middle of the thread,and make assumptions that aren't valid.
Once more...Start up,take off ,climb to altitude shut down ,glide, land.
Longevity , cooling, feasability, are unimportant..I'm doing it because I've always wanted to....I'm 71 yrs.better do it soon,eh ?
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Old Nov 16, 2012, 06:56 AM
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Earl,

On your early photos one aspect concerned me, but you probably have thought of that already. In any case, here goes: the shaft is pretty long and will need support. Two bearings, on at the tip and one in the middle would be enough.

Keep us posted on this project ;-)
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Old Nov 16, 2012, 07:09 AM
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Originally Posted by Patxipt View Post
Earl,

On your early photos one aspect concerned me, but you probably have thought of that already. In any case, here goes: the shaft is pretty long and will need support. Two bearings, on at the tip and one in the middle would be enough.

Keep us posted on this project ;-)
Yes-it's been considered.Actually,the front bearing/prop mount is a .70 size 4 cycle crankcase.It has been milled away to leave it as a bearing holder/thrust retaining prop mount.Soon pix will clarify that. a bearing will be added at 45% of the shaft to garble 'waves' and a universal will be used at the engine.
We are using the crankshaft as soon as we balance it to neutral,since the rod and piston have been removed.
Thanks for your input.
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Old Nov 16, 2012, 08:43 AM
Complete RC Idiot Savant
The Netherlands
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Quote:
Originally Posted by epoxyearl View Post
Oh -no Bert ! It's R/C..I'm sorry I didn't clarify that...Much too safety concious to allow something this big to wander around freely.
My intention is to build a large model representing a 32" original.
I've been considering ailerons as part of the wing construction,as well.
Things are progressing nicely,but I'm having difficulty conveying my point.It seems folks pick up in the middle of the thread,and make assumptions that aren't valid.
Once more...Start up,take off ,climb to altitude shut down ,glide, land.
Longevity , cooling, feasability, are unimportant..I'm doing it because I've always wanted to....I'm 71 yrs.better do it soon,eh ?
Don't worry Earl, I followed from the start, but I just only saw the "take off, climb, shut down, glide, land" part, and thought it would be a little bit strange not to do that in RC. I really like this project, even though I am not nearly your age, I have had similar thoughts of enlarging the peanuts models I used to build but never could get flying straight....

Good luck realizing this project!

Brgds, Bert
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Old Nov 16, 2012, 12:21 PM
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So now,following the advice that I so needed,we've clarified that it'll be R/C-and due to the overwhelming agreement,the heli drive is gone,to be replaced by an Evolution .46 two stroke and a belt drive reduction.The 8.5 to 1 reduction has been upped to a 6.0? to 1 belt with one way clutch,but no automatic clutch-without the starter shaft of the heli,I'll need a boat belt to start it.-no biggie.
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Old Nov 16, 2012, 12:37 PM
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Chicagoland
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That's should be just about right. ~6:1 should put the 32x14 around 2300 RPM at about 1HP. The engine does just about that at 14k. I'd say it's a great match.

Greg
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Old Nov 16, 2012, 05:27 PM
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Thank you

I've gotten the information I needed to change the rotation of the engine,and I'll have results posted after I run it...
We aren't going to use it now,as it has too much HP for the project.

The Sparky is using an Evolution .46 and a 6 - 1 belt drive reduction to turn the 32" prop at around 2k,plenty for the model.
I want to thank all the Engine Masters for your patience,input ,and support..These projects are important to me,and helpful people make me feel not so stupid trying them.
I'll leave the thread open for new information,and drop a bomb.!
Can you visualize a P-63 with the engine behind the pilot? I thought so.....put 2 and 2 together ....why did I need a looooonnnnng shaft to turn a large prop ???
Wait'll NEXT year ! Thank guys.
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Old Nov 17, 2012, 03:37 AM
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Belgium
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Quote:
Originally Posted by epoxyearl View Post
I've gotten the information I needed to change the rotation of the engine,and I'll have results posted after I run it...
We aren't going to use it now,as it has too much HP for the project.

The Sparky is using an Evolution .46 and a 6 - 1 belt drive reduction to turn the 32" prop at around 2k,plenty for the model.
I want to thank all the Engine Masters for your patience,input ,and support..These projects are important to me,and helpful people make me feel not so stupid trying them.
I'll leave the thread open for new information,and drop a bomb.!
Can you visualize a P-63 with the engine behind the pilot? I thought so.....put 2 and 2 together ....why did I need a looooonnnnng shaft to turn a large prop ???
Wait'll NEXT year ! Thank guys.
Talking long shafts how about this one ? Made on special order by machinist/guru Gert Lang from Germany. But I do'nt know what airplane it was for, still a little too short for a King Cobra though. But I remember reading in some model magazine in the past about someone having built a P-63 with the engine in the middle.
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