interesting OS 29

Went by a local hobby shop today. They had received engines and RC kits from an estate. One of the items was an old OS 29 that looked like someone had taken a control line engine and added a device with a butterfly valve above it to make the engine RC. Have any of you seen this setup before, it was something new for me.

>Went by a local hobby shop today. They had received engines
>and RC kits from an estate. One of the items was an old OS
>29 that looked like someone had taken a control line engine
>and added a device with a butterfly valve above it to make
>the engine RC. Have any of you seen this setup before, it
>was something new for me.

Funny, but the early RC engines were control line (or free flight) engines converted to RC. Nowadays we take an RC engine and make into a controlline engine. The buterfly was added to keep the fire lit when the engine was throttled back. It added enough back pressure to do the job. That was before mufflers. Nowadays the muffler will add enough back pressure of its own so the butterfly is no longer needed.

Leonard

The butterfly wasn't over the exhaust, I've seen that many times. This was over the venturi to restrict airflow into the engine (looked like the carb on a car and worked the same). Don't know if this is something someone made special for the engine if it was something that could be purchased. The engine was a 29S with a bell shaped venturi and a needle valve assembly you would find on a normal control line, or freeflight engine it had steel fins/sleeve unit.

Hope this helps an engine expert here.

TIA
Carl

Carl: This was a single exhaust model, right?

Next time you are there, check what it says on the case.

You can go to the OS History website and see if you can find a similar engine, perhaps without the butterfly. You can get to it through Phil Brown's listing of various CL sites.

I am not an OS Enines model expert, but are you certain that the engine was a Max-S .29 instead of the model previous to the "S" model? I thought that there was no Max-S .29, only the Max-S .30 and .35. Both those engines had a caburetor or venturi insert, didn't they?

That's the way the first OS R/C engines were. It makes a good stunt engine.

The link below from the OS timeline shows a .15 with what sounds very much like the carb you described.

None of the larger engines are shown with this carb but I know the timeline isn't complete because I have 2 versions of the 29 Max II but only one is shown. For the timeline itself, go to
http://www.osengines.com/history/ostimeline01.html

That is it only in a 29 size. Your photo looks like it has an exhaust cover too. The one i saw had nothing over the exhaust.

Hi,
I don't pretend to be an expert on OS stuff,but I know that the early versions of the MAX 111 29 & 35s ( shiny case and serial # on
L.H. mounting lug )had the throttle set-up you describe.
BOB ALLAN.

RetredNed
Bob Allen