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General control line discussion => Open Forum => Topic started by: Clint Ormosen on October 10, 2007, 11:50:29 PM

Title: Chipmunk engine?
Post by: Clint Ormosen on October 10, 2007, 11:50:29 PM

Some of you know that I started a JVL Chipmunk kit for VSC 20. My intention was to use a Brodak 40 in it, as the plans show. But I also have a new OS 46LA that I could use. I like the Brodak engine run and am not familiar with the OS 46. Is there really enough of a power difference to justify going to the 46? Also, the 46 is taller and will be harder to hide in the cowl.
Opinions?

Title: Re: Chipmunk engine?
Post by: Dan McEntee on October 11, 2007, 01:16:11 AM

  The .46 will also require you to use .018 lines. If the plane finished out anywhere under 50 ounces, I would go with the .40. I have flown a Super Chipmunk quite a bit with .40's and .46's, and i like the smaller lines better. If I felt I had to have a .46 in it, it would be a classic ST .46. Properly trimmed, that combo can handle the extra drag of the .018 lines, I think.
   What kind of kit is it?
   Good luck and have fun,
    Dan McEntee

Title: Re: Chipmunk engine?
Post by: Clint Ormosen on October 11, 2007, 04:11:17 AM

Oh yeah, I forgot about the 018 line requirement for the .46. I don't want to do that. The Brodak will be fine.

Quote from: Dan McEntee on October 11, 2007, 01:16:11 AM

   What kind of kit is it?
   Good luck and have fun,
    Dan McEntee

The kit is one of Walter Umland's kits. The classic legal VanLoo Chipmunk.

Title: Re: Chipmunk engine?
Post by: steven yampolsky on October 11, 2007, 06:46:46 AM

I fly my JVL Chipmunk with B40. It has PLENTY of power plus like Dan wrote: .015 lines are not allowed with LA46.the model also balances properly with B40. With LA46 you will need to add tail weight.

Title: Re: Chipmunk engine?
Post by: john e. holliday on October 11, 2007, 08:58:06 AM

As stated, go with the B-40.  I remember back in the 70's a young man building and flying the Sig Chipmunk as designed by Jim Van Loo kit.  It was powered with a Fox Stunt 35 that was box stock with no muffler.  it was flying so slow I kept waiting for it to fall out of the air.  He would do the whole pattern, but, would not fly competition.  Keep us posted.  DOC Holliday

Title: Re: Chipmunk engine?
Post by: Clint Ormosen on October 11, 2007, 09:59:16 AM

The Brodak it is. Thanks for the imput guys.

Title: Re: Chipmunk engine?
Post by: Randy Powell on October 11, 2007, 10:51:21 AM

Pete Peterson's awesome Van Loo Chipmunk (also an Umland kit) uses a Brodak 40. Pete's dinked around with it a bit and it runs very well. Plenty of power.

Does Brodak still sell this engine with the giant venturi? A friend had one that kept running away on him unless he overloaded it with a big prop. We finally got him to change out the enormous stock venturi for a smaller one and it solved the problem and the engine runs great and very consistent. Just wondering.

Title: Re: Chipmunk engine?
Post by: Clint Ormosen on October 11, 2007, 11:20:54 AM

Randy, as far as I know, they still come with the tall venturi. So does the .25.