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O.S. 91 SHAFT TOO SHORT - 7/29/2008 8:55:22 PM   
msimi



Posts: 127
Joined: 2/13/2003
From: Danville, CA, USA
Status: offline 		Gotta' pretty unusual situation. Anyone got an answer? I have converted an O.S. 91 C-Spec to power a GP Lancair ES. Runs perfect BUT... After mounting a spinner back plate and a thrust washer there isn't enough thread on the crankshaft to support a prop nut. Even a Dave Brown adapter doesn't grab enough threads. Even counterbored the prop center hub a bit. Any deeper might weaken the prop.
       Post #: 1

RE: O.S. 91 SHAFT TOO SHORT - 7/29/2008 10:14:02 PM   
w8ye



Posts: 18114
Joined: 12/11/2001
From: Taylortown, OH, USA
Status: online 		Tru Turn makes a spinner adapter barrel nut with a pretty deep reach.

I couldn't get the Tru Turn site to come up but here is a link to Central Hobbies which the detail is not as good
http://www.centralhobbies.com/spinners/truadapt.htm


< Message edited by w8ye -- 7/29/2008 10:17:31 PM >

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Attended the CutFinger Institute of DirtNap University for years but never did graduate....

Club Saito Member #7
Original AMA #31261

(in reply to msimi)
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RE: O.S. 91 SHAFT TOO SHORT - 7/29/2008 11:41:58 PM   
ChrisAttebery



Posts: 425
Joined: 9/15/2004
From: Gilroy, CA, USA
Status: offline 		What prop are you using? One solution is to find a prop with a shorter hub. For instance, two popular props for the Saito 82 are the MAS 14x6S2 and the APC 14x4W. There's quite a bit of difference in the thickness of the hub between the two. That C-spec motor is high reving and would probably be happy turning a low pitched prop.

The other solution is to have a custom prop nut made. The nut would have to be turned down to fit inside the prop hub. Think of it like a T nut. The T would be the hex to tighten the nut with. You'd probably have to bore the hub of the prop out to allow enough meat in the threaded portion of the nut.

Good luck,


Chris

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WM T-34 - OS 46AX - Club racers
Rusty Miss Ashley - Nelson Q40

(in reply to w8ye)
       Post #: 3

RE: O.S. 91 SHAFT TOO SHORT - 7/30/2008 12:37:55 AM   
w8ye



Posts: 18114
Joined: 12/11/2001
From: Taylortown, OH, USA
Status: online 		This nut is your thread size and will reach under the prop to catch the threads and it has the spinner threads in the end.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCT61&P=7

< Message edited by w8ye -- 7/30/2008 12:49:47 AM >

_____________________________

Attended the CutFinger Institute of DirtNap University for years but never did graduate....

Club Saito Member #7
Original AMA #31261

(in reply to ChrisAttebery)
       Post #: 4

RE: O.S. 91 SHAFT TOO SHORT - 7/30/2008 2:49:45 AM   
msimi



Posts: 127
Joined: 2/13/2003
From: Danville, CA, USA
Status: offline 		PURRRRRFECT!!

Ordering tonight from Tower. I thank you... The Lancair thanks you... The wife? Eh, not so much. "$28.99??!! Are you crazy??!!
Aw well, she'll get over it.
Your input came just in time. I was about to gaul a second adapter and risk messin' up the shaft. The prop that I tested on Sunday is a three blade MAS 14x9. Have not tached it yet but it seems to have a lot of pull. Hope it is sufficient to fly scale.

(in reply to ChrisAttebery)
       Post #: 5

RE: O.S. 91 SHAFT TOO SHORT - 7/30/2008 4:53:39 PM   
ChrisAttebery



Posts: 425
Joined: 9/15/2004
From: Gilroy, CA, USA
Status: offline 		Amazing, that's pretty much what I was thinking.

quote:

ORIGINAL: w8ye

This nut is your thread size and will reach under the prop to catch the threads and it has the spinner threads in the end.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCT61&P=7


_____________________________

WM T-34 - OS 46AX - Club racers
Rusty Miss Ashley - Nelson Q40

(in reply to w8ye)
       Post #: 6

RE: O.S. 91 SHAFT TOO SHORT - 7/30/2008 5:51:39 PM   
msimi



Posts: 127
Joined: 2/13/2003
From: Danville, CA, USA
Status: offline 		When I get this beast all together I'll have to bring it down to Tomcats after the maiden.

(in reply to ChrisAttebery)
       Post #: 7

RE: O.S. 91 SHAFT TOO SHORT - 7/30/2008 8:46:10 PM   
ChrisAttebery



Posts: 425
Joined: 9/15/2004
From: Gilroy, CA, USA
Status: offline 		Sounds like a plan.

I almost bought one of these motors for a large profile. I wasn't sure it would spin a big enough prop so I passed on it.

_____________________________

WM T-34 - OS 46AX - Club racers
Rusty Miss Ashley - Nelson Q40

(in reply to msimi)
       Post #: 8

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