OS .15 GV

[bill marvel]

Bob Zambelli and I have been exchanging messages about this pretty little OS .15 Max.  Neither of us had heard of a GV model.  I have no idea where I got it or how long I have had it.  I suspect it was in a box of junk airplane parts and engines given to me by a friend of my son some 20-25 years ago.

Bob and I are trying to identify the shaft thread.  I want to build a Perky racer and need a spinner adapter nut for it.

Anyone familiar with this engine?

bill marvel

[bill marvel]

Here's a couple of more pictures to help.

Regards
bill marvel

[bill marvel]

And, one more (This is kinda fun.  I have not taken or posted pictures on this forum before.  It is incredibly easy!!!)

bill marvel

[Richard Grogan]

I think I have an RC version of it. Let me check...

[rustler]

Surely it's the standard MAX O.S. 15, which superseded the MAX-III 15. The undrilled bosses in the exhaust stack indicate it was supplied with the O.S. strap on silencer. The GV letters under the mounting lug are typical of O.S. markings, and a source of much mystery. So far nobody has explained the logic behind the system!

[Annette Elmore]

I thought all OS MAX's prior to the Max-s 35/20/25 had separate steel cylinder heads the one piece crancase with a slide in liner only came with the aforementioned engines.

This would make this the same era as the 20/25 although i've never seen one with the hefty lump of metal at the bottom of the venturi!

Looking up on the OS History site lookee here:





http://www.osengines.com/history.html



Tony

[Annette Elmore]

I asked them what this one was:








They said it was a Max-ii although the frontal treatment looks a bit different to the one on their site:



Tony

[Steve Helmick]

As stated above, this is the model commonly called the "S" (right or wrong) between the Max III and the FP series. There were .10, .15, .20, .25, .30 and .35 in this series. I believe the .40's were all "H" types, with ball bearings, and there was a .35H with a single rear bearing and front bushing, for combat.

I bought a .10 "S" R/C for a Livewire Rebel I framed up for my brother, as a Christmas gift, sometime in the early '80's. I also had a .20 "S" CL for a trainer for my son, and I had a .35S for my Mathis Excalibur, built in '67/'68. I wasn't that impressed with the .35S. It would 'runaway', tho I didn't know that was what was happening, and the rods wear out rather quickly. A lot of this was fuel shortcomings, I know. I didn't know anybody around here flying CL Stunt then. If you run it, use something with a lot of castor, like 10-29 Powermaster, and don't expect it to run like an FP. I'd rather have an FP or LA, actually.  Steve

[Annette Elmore]

I've 2 OS-MAX-S 35's - I've also bought 2 of Leonard (Stuka Stunt) Neumann's replacement bushed conrods....

[James Lee]

According to Jim Dunkin's 'Reference Book of International .15ci/2.5cc Model Airplane Engines' the OS 15 shown at the start of the  thread is a 1975 version of the OS Max 15.  The OS max preceding it was the Max-III with the steel fins....
Jim 

[dennis lipsett]

To the best of my knowledge there was never a series of motors from OS called the S series. The motors that you call that including the beloved OS 35S were part of the F series from OS. They were supplanted by the FSR series then the SF,SX,FP,AX

[john e. holliday]

Okay fellows, if in doubt about the thread size, I suggest a trip to your local Ace Hardware with engine in hand and go thru the metric section of hardware.  My store also a gauge to check with before going to the bins.  DOC Holliday