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Engine basics => Engine set up tips => Topic started by: Manuel Cortes on September 20, 2006, 01:28:31 AM

Title: OS 30s
Post by: Manuel Cortes on September 20, 2006, 01:28:31 AM

Hello all;
I´ve restored two OS30s, previously RC but now converted CL with a .270 venturi insert and stock silencer (OS 703 model).They are in impressive order and I´m thinking to use in a stunter.
What prop do you recommend for these engines?
There is a lot diference between them and the 35s?
And finally, what do you think about the correct size plane for them?
As allways, thanks for your time.
Regards.
Manuel.

Title: Re: OS 30s
Post by: Tom Perry on September 20, 2006, 06:31:32 AM

Manuel,

I have a few of those engines and have run them on the bench with a wooden  9-5.  I am going to use them on a lightly built Ring Master.  I have seen them run on Flite Streaks with good results.  I will use a 9-5 or a 9-6 on the Ring Master as a starting point.  I use 5 or 10% nitro with 29% castor.  The con rods on this engine appreciate it.

Others with more experience may have a different view.   #^

Title: Re: OS 30s
Post by: Manuel Cortes on September 20, 2006, 01:16:47 PM

Thanks very much, Tom.
About your coments I can expect power slightly below than a standard Fox 35, isn´t it?
I flew a Nobler (29 Oz!!!) some years ago with a Merco 29 with spectacular results, up to tail cracked in a corner (too light, snif, snif) but it was an eye opener about stunters weight.
I´ll wait for more comments, guys!

Title: Re: OS 30s
Post by: Bill Little on September 20, 2006, 08:13:28 PM

I don't know that the OS 30S is much weaker than a "standard" Fox 35.  The OS 35S is a good bit stronger than the Fox 35, and I am guessing (I have an OS 30S) that the 30 is almost an equal.  I like a 9 1/2" X 5 wood prop (cut down 10").

Bill <><

Title: Re: OS 30s
Post by: Tom Perry on September 21, 2006, 07:40:02 AM

Just as the fox .29 and .35 stunt sleeve and piston are interchangeable so are the os .30 and .35.  I like all the engines mentioned and think they all run pretty well.  The OS's run better with the muffler than the foxes do and the fox engines seem to have more vibration. 

There are so many different props to choose from now than in past times you shold be able to find one that runs well for you.

I like to use wood props because frankly the composite props and the damage they can do scare the hell out of me.

I recently bought some 9-5 and 9-6 power props and they seem to work ok. on any of these engines.

Title: Re: OS 30s
Post by: Bill Little on September 21, 2006, 06:10:17 PM

Hi Tom,

I recently found a cache of Aldrich Custom 9-6 props.  They are SWEET!!!!!!!!!!!!!!  Look a lot like the paddle blade TF props.

Bill <><

Title: Re: OS 30s
Post by: Manuel Cortes on September 22, 2006, 02:26:59 AM

Thanks very much for your kind responses, I´ll give OS30 a try!!Probably a 91/2 x 5-6 will be a nice starting point.
Regards from Spain.
Manuel.

Title: Re: OS 30s
Post by: Phil Spillman on September 26, 2006, 08:34:46 PM

Hi Manuel, I agree with Bill Little and will add the suggestion that you try the Master Airscrew 9.5 X 6 prop. This is a specific prop made by MAS not a cut down version, although that will work as well, that I prefer for the .30,.35 O.S. engines as well as the Fox .35's. The OS engines, S varieties like you've got, are superior to the Fox engines in my experience stock to stock. I think that the venturi ID is critical in the successful running of these old engines.
You might have a machinest friend drill out two holes in the exhaust stack for the fitting of a Big Art type tube muffler. Also use at least 25% total oil in the fuel mixture. These engines are delicate and will scorch on typical RC types of fuel.
 Phil Spillman

Title: Re: OS 30s
Post by: Manuel Cortes on September 27, 2006, 02:58:19 AM

Thank you very much, I´ll try this prop!! ;D
Regards form Spain.