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Vendors Corner => LEE MACHINE SHOP => Topic started by: Bob Reeves on October 25, 2011, 06:30:36 AM

Title: Hey Jim, prop shaft extension?
Post by: Bob Reeves on October 25, 2011, 06:30:36 AM

I'm thinking about the feasibility of building an A4 for carrier with an OS 61 RR. The big problem is because it's a delta the engine would have to be located behind the canopy or it would need 15 ounces of tail weight. I'm thinking it will need a prop shaft extension but not sure how long till I figure out how big the thing will need to be.

Wonder how long I could go till I would need a carrier bearing and if I use a carrier bearing how will it get lubed. Would a sealed bearing hold up with a 61 turining 20 grand? Might be able to cut the length needed for the shaft extension with a custom spinner? So what ya think?

Title: Re: Hey Jim, prop shaft extension?
Post by: James Lee on October 25, 2011, 08:25:44 PM

Bob
Try running a line from the muffler and let the exhaust oil give the bearing a bath.....
How about some drawings...?
Thanks
Jim   

Title: Re: Hey Jim, prop shaft extension?
Post by: Tim Wescott on October 25, 2011, 08:41:03 PM

Go ducted fan?

Dick Sarpoulis did a Hanriot Biche H 110 in Flying Models in 78 or some such.  It was a pusher; he put the engine in front with a boat propeller shaft back to a crank case in the rear; he fed the rear crank case with oil from the exhaust.

So it's been done, and been reported to work.

Title: Re: Hey Jim, prop shaft extension?
Post by: rustler on October 26, 2011, 03:22:47 PM

I would think the prop drivers on the McCoy 60 are about as long as you would try as a pure cantilever extension, without a bearing. Similarly the extension on the K&B 7.5 DF engines. The revs those engines reach indicate it's an acceptable length if done to a high enough engineering standard. The longer the extension the more exagerated any slight misalignment becomes.