What size gas engine for airplane?
01-01-2016, 08:20 PM
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What size gas engine for airplane?
I am thinking about a 10cc or a 15cc gas engine, I only want to buy one class of cc size. I am thinking .45 to .60 size sport aerobatic arfs, I am concerned that the 10cc would be a dog on a 60 size airplane, and the 15cc would be too much on a .45 size ? so if either engine will fly both 45 & 60 size airplanes well, which one should I choose ? also what brand: Evolution or RCGF ? thanks for your help
Last edited by dandeeman; 01-01-2016 at 08:27 PM.
01-02-2016, 05:29 AM
#2
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This depends, big time, on your expectations regarding this planes performance. I don't think you're going to find a "fitsall" engine for .45-.60 size planes. Actually I know you aren't. There's too big a range there.
While pondering the subject, compare the weight of a 15cc engine to a DLE 20. Pretty darn close, and the 20 will blow a 15 into the weeds. One of the most spectacular sport/acrobatic planes around are the 70" Great Planes Revolvers. Designed for a 60 originally, 20cc power turns them into something that puts big grins on a lot of faces. That's heads up flying though.
The Evo 10 works great in sport planes with about 650 sq in of wing, as long as you keep it under 6.5lbs or so. Vertical will be good, but not unlimited. For unlimited, you need to be closer to 5lbs, which is getting pretty light for even a .45 size plane. I've spent the last few seasons figuring that out.
RCGF 10 hasn't been out long enough to have an established track record. I've heard some good things, like it will swing 14" props, which puts it into the performance class of some of the 15cc gassers.
Bottom line, you have to be very careful with wing loading to get a great sport/acrobatic plane. Picking the right engine critical - especially in these smaller classes.
While pondering the subject, compare the weight of a 15cc engine to a DLE 20. Pretty darn close, and the 20 will blow a 15 into the weeds. One of the most spectacular sport/acrobatic planes around are the 70" Great Planes Revolvers. Designed for a 60 originally, 20cc power turns them into something that puts big grins on a lot of faces. That's heads up flying though.
The Evo 10 works great in sport planes with about 650 sq in of wing, as long as you keep it under 6.5lbs or so. Vertical will be good, but not unlimited. For unlimited, you need to be closer to 5lbs, which is getting pretty light for even a .45 size plane. I've spent the last few seasons figuring that out.
RCGF 10 hasn't been out long enough to have an established track record. I've heard some good things, like it will swing 14" props, which puts it into the performance class of some of the 15cc gassers.
Bottom line, you have to be very careful with wing loading to get a great sport/acrobatic plane. Picking the right engine critical - especially in these smaller classes.
01-02-2016, 11:57 AM
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I like this engine.
http://www.agaperacingandhobby.com/v...?productid=517
It may not be the most powerful but that front carband steel cyl makes it the most reliable
http://www.agaperacingandhobby.com/v...?productid=517
It may not be the most powerful but that front carband steel cyl makes it the most reliable
01-02-2016, 05:48 PM
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I like this engine.
http://www.agaperacingandhobby.com/v...?productid=517
It may not be the most powerful but that front carband steel cyl makes it the most reliable
http://www.agaperacingandhobby.com/v...?productid=517
It may not be the most powerful but that front carband steel cyl makes it the most reliable
01-02-2016, 07:35 PM
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They have that clapper valve in the back. Its just an extra part that can cause trouble.
Also puts the carb burred in the back where you cant get at it.
I have a DLE 30, an RCGF and an NGH.
The DLE took me six months and a note from Frank Bowman to get running properly.
The RCGF seized when I first ran it. RCGF replaced it but I still have not got a decent run out of it. I probably can fix it but I am tired of fooling with it.
Also puts the carb burred in the back where you cant get at it.
I have a DLE 30, an RCGF and an NGH.
The DLE took me six months and a note from Frank Bowman to get running properly.
The RCGF seized when I first ran it. RCGF replaced it but I still have not got a decent run out of it. I probably can fix it but I am tired of fooling with it.
01-03-2016, 08:42 AM
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Yes, I formed my opinion when I spent six months getting the back end of that DLE properly sealed and the reed valve cage smoothed out. I need to do that on the RCGF.
In the meantime the NGH has been through 4 airplanes and three crashes and is still running strong. I have to use 25/1 fuel because it is an early one without needles on the rod, but oil is cheap
One other thing. The RCGF siezed because the needles on the rod came apart. I think you are better off with a plain bearing on the rod with those smaller gas engines. Just use more oil.
Nitro engines have done that for years and they produce more power than the equivalent size gas engine
In the meantime the NGH has been through 4 airplanes and three crashes and is still running strong. I have to use 25/1 fuel because it is an early one without needles on the rod, but oil is cheap
One other thing. The RCGF siezed because the needles on the rod came apart. I think you are better off with a plain bearing on the rod with those smaller gas engines. Just use more oil.
Nitro engines have done that for years and they produce more power than the equivalent size gas engine
Last edited by dirtybird; 01-03-2016 at 08:52 AM. Reason: more info
01-06-2016, 06:35 AM
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Thanks for all the help. I will be able to refer to this info in the near future. I am leaning towards the RCGF and will use more oil just to play it safe. The info about the square inches of wing, weight of plane, using the evo 10 is a very helpful start. Does the following sound like a good basic starting point (depending on type of airplane, performance, prop size etc...) ? 10cc for 45 size airplanes, 15cc for 60-75 size airplanes, 20cc for 120 size airplanes ? Thanks
01-06-2016, 08:48 AM
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I'd be pretty careful with that. For example there are under 5lb .45 size planes, and there are 6.5-7lb .45 size planes. It should be easy to see the effect those weight differences might have on a 10cc gas engine's performance?
The same holds true of the others. At best, you'll just be in the right ball park with those assumptions.
Suggest you look at it a different way, with more emphasis on weight (finished, ready to fly) and wing area, and much less emphasis on suggested engine size. I gave you about what to expect for the 10cc above. For the 20cc, you're looking for 850 sq. in. wing or larger, and no more than 10lbs for great sport performance (unlimited vertical). For 20cc 3D, you'll need closer to 1000 sq in and try to keep it under 8.5-9lbs.
A lot of guys use thrust to weight ratios when thinking 3D, with 1.5:1 minimum. So a 10lb plane will need about 15lbs of thrust on tap.
Playing with those numbers (thrust to weight), you'll see how these 100cc planes seem to execute without stress.... It's these smaller ones that struggle.
The same holds true of the others. At best, you'll just be in the right ball park with those assumptions.
Suggest you look at it a different way, with more emphasis on weight (finished, ready to fly) and wing area, and much less emphasis on suggested engine size. I gave you about what to expect for the 10cc above. For the 20cc, you're looking for 850 sq. in. wing or larger, and no more than 10lbs for great sport performance (unlimited vertical). For 20cc 3D, you'll need closer to 1000 sq in and try to keep it under 8.5-9lbs.
A lot of guys use thrust to weight ratios when thinking 3D, with 1.5:1 minimum. So a 10lb plane will need about 15lbs of thrust on tap.
Playing with those numbers (thrust to weight), you'll see how these 100cc planes seem to execute without stress.... It's these smaller ones that struggle.
Last edited by ahicks; 01-06-2016 at 08:52 AM.
