Gas conversion chart? Make it simple! Please.
 

Ready to go to gas permanently! Well, maybe not for every model, but certainly for some. Especially for those on the drawing board.

Is there a "shortcut to CC's" That is, a conversion chart which will easily tell you what gas engine to use to replace what you have?

Or a chart that spells it out for you easily?

All I know is two and four cycles, and wouldn't know how to choose a gas engine to replace what the two or four's are doing?

Thanks in advance!

CK

RE: Gas conversion chart? Make it simple! Please.
 

That is a long and hard question to answer.

All in what type of plane and how you want to fly it.

I have all way's used 78-80" for the point of using gas over glow for the wing loading but there are some pretty light smaller gas engines now that could change the rule.

If you could tells us what you have on the drawing board might be able help you better.

Milton

RE: Gas conversion chart? Make it simple! Please.
 

I guess what I am trying to say is if you had a Telemasters with a 96" wing span you could fly it with a 38-45cc motor but if you had a 98" Extra or Edge you would need a 80-100cc engine.

Milton

RE: Gas conversion chart? Make it simple! Please.
 

There are 16 and a fraction cc's in a cubic inch but there isn't a direct relation from one type of engine to another. Most of the newer kits and arfs will give the engine range in glow and gas. Look at the ads in the magazines. There are some smaller engines on the market that would work in 1.20 to 1.50 sized airplanes. People have even put gassers on the Funtana 90 that normally uses a glow 91 FS. The problem you run into is that a plane designed for glow may require cutting the cowl all to pieces to fit in a gasser and its muffler. To go Gas or Glow can also depend on the airframe and the firewall. May have to add structure which adds weight. There is no simple answer. A plane with a tapered cowl may hide a glow engine but a gasser is halfway out the bottom.

RE: Gas conversion chart? Make it simple! Please.
 

Every plane is different, like they said. Really no set formula. I just ordered a SV26 that has a rear carb and pitts muffler for a Carl Goldberg Ultmate. I picked it up with only a few flights on it. The guy had a Magnum .65 on it and had to add nose weight. Total for engine, muffler, mount, and weight was 2 pounds and 6.6 ounces! The SV26 will add a pound of weight. I'll be able to use a little bit smaller fuel tank also to save weight. The plane with the glow engine weighed 8 pounds 3 ounces, with a wing loading of 19.03oz. With the 26 the weight will be 9 pounds and 3 ounces and the wing loading with be about 21.5oz. Pretty good for a biplane. Nothing will stick out the side of the cowl. Engine will hang out of the bottom though. That's OK by me, it'll be nice'n cool.[sm=shades_smile.gif]

RE: Gas conversion chart? Make it simple! Please.
 

You guys are great, thanks for the replies.

Milton,

This is the model I have on the drawing board. I already asked about engine choice a while back, and the results were all over the place.

This model will be 80" in span the cord is 10". The nose moment is way out there! So weight is a factor. I have a Webra 1.2 two stroke I thought I'd use. I hate cleaning up the fuel mess, especially on a bipe.

When glo engines are converted to spark, like CH Ignition, do they burn gas or glo fuel. I have no idea about that? Is this an option?

The thin nose would be altered with a gas engine.

RE: Gas conversion chart? Make it simple! Please.
 

I don't know much about full scale planes but that one looks like a full scale with a Turbo prop engine.

That said with a 80" wing span and if no more that around 15-17 pounds most any good 40cc should fly it well, You could go smaller but the power would not be there if you need it.

Now if nose weight is a problem and you have to keep it down I am sure a 26-30cc would fly it scale like and not be any extra there if you needed it, you did not say what the all up weight is suppose to come out to be.

A 120 four stroke is equal to about a 20cc gas engine, But gas engines do not put out as much power per cc as glow.

Just think about a chainsaw, That is really all our RC gas engines are but just made for RC use, So regular gas with oil mixture and you are ready to go, Most gas engines will have some instructions on to how to mix the oil and gas for break in and after break in.

Milton

RE: Gas conversion chart? Make it simple! Please.
 

The "old" days of gas conversions used 1 cubic inch per 10 pounds of airplane for a rough starting point, but that went in the sewer with 3d:)

RE: Gas conversion chart? Make it simple! Please.
 

After making the post about the chain saw I remembered something that happened in 1978 or 79

A guy came out to the Flying field with a chain saw all taken apart talking about how he was going to fly a model plane with it, We all thought yea just keep on dreaming, Well I guess we were the ones dreaming. :)

Milton

RE: Gas conversion chart? Make it simple! Please.
 

Milton,

I'm not smart enough to figure out the weight "before" a model is built.

OK, a 120 4S is equal to a 20cc gas, so where would a 1.2 two stroke be? What about a 1.8 two stroke?

Maybe I should stay with the engines I have and get used to the clean up.

This is actually the model I'll be doing. The nose is a bit different.

Charles

RE: Gas conversion chart? Make it simple! Please.
 

http://joshmadison.com/article/downl...t-for-windows/

Go there and download the conversion program for easy future referencing in various things. If the link doesn't work just Google "convert" and connect to the one by Josh Madison.

RE: Gas conversion chart? Make it simple! Please.
 

I just use the number 6 Not exact but is close enough

50cc X 6 = 3 ci

1.6 ci divided by 6 =25 cc
1.8 ci divided by 6 = 30cc

Works for me.

Milton

RE: Gas conversion chart? Make it simple! Please.
 

You should see if it's OK with the engine before putting it in an airplane that ugly. Goood lord!

RE: Gas conversion chart? Make it simple! Please.
 

True, but the full scale will carry a whole lotta weight and turn inside a dime.

RE: Gas conversion chart? Make it simple! Please.
 

Might be so but it looks as if the second one has never bothered to clear a fence.

RE: Gas conversion chart? Make it simple! Please.
 

Man those are crop dusters from way back, A model of it took first place at Top Gun this year.

Milton

RE: Gas conversion chart? Make it simple! Please.
 

Opps that is a two winger, The Ag Wagon is a single wing

Milton

RE: Gas conversion chart? Make it simple! Please.
 

Guys,

Thanks for the complements.

There's an outfit in Texas that takes the Ag Cats and turns them into forest fire fighters.

Milton,

Nice website! Your Area 51 offereing may be suitable for my Skyshark P-40?

I should be doing your graphics.

Charles

http://www.cfcgraphics.com

RE: Gas conversion chart? Make it simple! Please.
 

Look like a cool project and a biplane with an 80-inch wing and all that drag from scale detail I would go with a 50 CC to a 62 CC. I would think your flying weight will be 22 to 24 lbs and you may want to have power to fly it scale like with good vertical. I had a G 62 set up from Ralph at rcignition.com with a shaft extension to move the cylinder back in side a scale cowl and to move the weight back. Works great because the head did not stick out of the cowl. I have a Webra Bully 35 CC that I had a shaft extension made to keep from adding tail weight. Engines with electronic ignition will be easier to change, look for an engine that can be changed easy. Ralph made me 2 different G 62s both having special prop shafts. The extra cost is worth it, saves weight and improves the look of scale cowls.