I'm not sure whether this belongs here or in the vintage forum, but since it looks like it was originally a ducted fan I'm hoping some of you know something about it.

http://cgi.ebay.com/os-61v-gear-redu...#ht_500wt_1182

This is not my engine, I am not promoting it, I do not know the seller and have no stake in the auction I linked to. I'm wondering if any of you have ever seen one of these before or know what OS was trying to do with it?

As I recall, the .61VF was a ducted fan engine, and I'm guessing the reduction gearbox was a way to turn a bigger prop at a lower speed, but why? It seems to me like it was a really complicated and expensive solution to a simple problem. And I can just imagine the complications it brought, like cooling the gearbox and shearing teeth in the event of a prop strike.

On the other hand, I bet it would sound really cool in a Mustang on a low pass at high RPM screaming through a tuned pipe and a whining gearbox...

That thing looks too cool....if I had some extra cash it would be a new toy.

The real Mustang had a high RPM engine running through a whining gearbox...

That engine must have been their answer to the "Byro-drive" 60s.
I wonder how many were made?
I wonder how many were ever sold?

I can't see that engine lasting the weekend...............

Well when that engine was built there weren't very many (if any) giant scale engines.....so this was one of the first examples of trying to swing a bigger prop at all costs...at that time people were trying to gang two 60's together to swing the big props...(aka hannos dalotel). I have only seen one run and it pretty much knashed along with all the gear noise. The bigger engines (and the gas engines) killed the idea (along with the associated problems of a gearbox).

Steve

these os engines were OS effort at larger props for quieter turnaround pattern they werent a sucess besides being nosey as well, there were two ratios offered, and a rear exhaust version as well RIP FWIW

a prop strike could/might do in the gear box ????[:@]

I don't know much about this whole thing but a guy at my field has this same engine and gearbox from OS and it seems to have been used good and hard with no wear and tear on the gears. I thought it was just the weirdest thing coming from OS when I saw it... That's my ~1.5cents

OS made a few different versions of that engine back in 1982.





http://www.osengines.com/history/ostimeline09.html

Steve mention that it was to sving a big prop at all cost. Ithink rules and regulations did have somethting to do with it too. FAI did at the time not allow engines larger than 10ccm (.61cid) in competition. Then, if you wanted to use a big prop or you could gain an adventage in competition by doing so, a geared engine was the ansver. In free flight geared glow or diesel engines is still in use as the rules call for a max engine size of 1.5 or 2.5ccm in some classes and maximum climb is wanted.</p>