gittarpikk

Ok I think it is time for a gear drive 1/2 A for planes like 3D's that fly slower and have to climb straight up...so a larger prop (lower pitch)can be used and get the better HP from higher rpms... Trouble is none are made... I remember seeing one..and it had a a small flywheel (yes thats weight) and I believe it was used on a sailplane... I do know that the IC stroke(verified by those in the know) will shred a belt drive in short order..so those are out... I had in mind a metal gear such as those on a R/C nitro car set in a U mount driving a shaft running on ball bearings and terminated in a prop hub. It looks like if one made the U-bracket out of something lite like kevlar ect.. it would not add much weight and the gains in much bigger props swinging a lower RPM would far outweigh the slight extra weigh added.
Perhaps there is a plastic gear drive that is used for an electric motor can be reworked by adding metal gears and save the engineering phase...
Any thoughts on this pleasae let me know... maybe some interesting co-developing.. I have the ability to market them is this is achievable
Mike

combatpigg

My Feedback: (3)

I would love some type of setup that would allow the turning of a 10-2 or 3 prop at a usable level of thrust for 3D with a .061. It would have to be all plastic with cheap, easy to change gears. The problem is that it is hard to get something from nothing and there is power lost in the gears. The prop shaft will need a pair of sealed ball bearings. I don't think you could get instant enough throttle response from such a measly engine[ moving this much machinery] but HOPEFULLY, I'm wrong.

mclintock

My Feedback: (3)

Hobby-lobby has some 480 type mpjet (yes, the mp jet that used to make the killer .061) gearboxes for three dollars! They look quite strong, and three dollars!

It would be a good start.. I think you might need a little flywheel for the engine.. Bo-link makes a line of cars using norvel .061 engines, maybe a flywheel from one of those.. There is a seller on ebay listing a bo-link modified norvel for 25 bucks buy it now...
I think he works at bolink or somethig..



[link=http://www.hobby-lobby.com/gear480.htm]mp jet gearboxes at hobbylobby[/link]

gittarpikk

Thanks for the info.. I found the gearboxes...but I also seen they had one for about $23 that was all metal , of convertional design (can be reworked with a different self-designed bodyplate) and had all the ball bearings etc.I did not find the Bolink reworked .061 at ebay... maybe you can link me if you can find it.. I would think that yes a flywheel might be ok... but a metal gear with a lower ratio maybe and no flywheel might save weight, performance and prevent the tearing up of gears due to the IC powerstroke of the nitro engine. If this works, maybe I could buy the individual parts bulk from Hobby-lobby or mpjet and have the bracket custom made (there is a very hi tech fab shop that can water-jet cut and laser cut parts only about 3 miles from here.

Geez... surely I'm not the only one that has wanted/attempted to do this...If so...this ought to be interesting..;-)

ajcoholic

My Feedback: (10)

We have discussed gear drive conversions for 1/2A's here before, try a search and see what comes up. I have fooled around a bit with them, and I want to try a belt drive (I for one think it WILL work, and better than a gear setup) as I have used it in larger engines for other purposes that were driven off the crank OK.

The problem is the gear system will weigh as much as the engine, so you are probably better off IMO just going to a larger engine.

But, experimentation is fun, and you never know. But plastic gears? I guarantee they wont last. Brass, aluminum or steel are necessary. Been there done that

AJC

Jim Thomerson

I have a Pewee 020 I got off ebay with an attached gearing and maybe an 8 x 4 prop. I've never run it, but I really ought to. There is a gear on the crank, a gear holder which clamps on the crankcase bearing area and about a 3:1 gear driving the propshaft. Real simple, probably well under an oz. I'm wondering about side loads on the crank.

Jim

gittarpikk

Hmmm can we get a pic of that?... shux , you KNEW that was coming though...!

gittarpikk

There is a guy seloling plans off ebay for $29 that has (2) used baby bee motors and the plans to make/machine a cool looking gear drive for 2 cox .049's for a twin arrangement...real simple also..(I just looked and its gone now). But I thought it might just work for a single engine as well.. sounds like what I might have seen

ajcoholic

My Feedback: (10)

The peewee unit was sold by Bob Kress if memory serves me right, I also had one.

The guy selling plans off ebay is using a picture of one of MY twins I made, and the plans are simply copied from an American Modeler magazine from the late 60's.

Do a search here, I posted my own drawings and instructions here on how to build them, and its FREE

AJC

ajcoholic

My Feedback: (10)

here is the link:

http://www.rcuniverse.com/forum/m_11...tm.htm#1199286

fritzke

My Feedback: (1)

And another:
http://www.rcuniverse.com/forum/m_12...tm.htm#1271052
Dave

Tom @ Buzzard Bluff

I just dug out my geared Pee Wee which I assume is the Kress unit and weighed it. With 7x4 Top Flite wooden prop it weighs 2.5 oz. on my digital scale. Hardly a lightweight. Too lazy to count gear teeth but definitely not 3 to 1.
I've never ran it because the gear mesh appears to be compromised. The gears only mesh half of their width. I can't believe that is a 'good thing'. The flywheel/drive gear is brass but the driven gear appears to be nylon or another slick, transluscent white plastic of some sort. From the looks of the piston I don't think it's ever been ran.
I see no adjustment for setting gear mesh but I think you have me curious enough to take it apart for a closer look. Tom

ZAGNUT

My Feedback: (1)

years ago i geared down an .049 reedy with something similar to the kress drive.

i made the hole in the mount plate larger than the nose of the engine's case and used an offset or eccentric bushing. this gave about 1/8" adjustment for the gear mesh and allowed experimenting with different gears.

for the large gear i used various nylon gears designed for glow powered cars and had no problems with stripped teeth.


dve