• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Building a foam board plane for a 25cc gas plane?

#1
I did not want to hijack the weed eater thread so I will start a new one. This will be after I learn to fly again.
Do you think it possible to build a foam board plane using the techniques used on FT planes to build a plane that would handle a 25cc gas motor? I would of coarse use some plywood to strengthen the plane in certain areas such as firewall, wing spares, landing gear mounts and so on. I was thinking some thing with a 6'-7' wing span and loosely based on a Cub.
Tell me what you think.

Casey
 

b-29er

Active member
#3
Using the concepts, yes. Using the techniques outside of FT materials...gonna get tricky. A lot of the FT plans use paper-on folds, meaning you cut a channel, fold the foam, and you get a strong glue joint with a build in clamp. Using larger foam insulation products, which would nearly be a requirement with the FT big foam not yet being available, you would need to tape each fold, unfold, and use an adhesive product. My preferred is gorilla, which works best when activated with water, which blows any chance of using tape to replace the paper out of the water.

If you're really tempted to go big, i'd go electric. As much as people like that whole gas motor noise, with it comes the gas motor weight, heavy vibrations, stresses from starting the motor, and the fact that many of the foams out there will be eaten by gasoline. And if you're still tempted to build a 25cc foam gas airplane, i'd do a canard. You're putting your weight and vibration right below a point on the aircraft that should already be strong, where the wing meets the fuse, and you're venting hot exhaust gases and oil behind the aircraft instead of down the side.
 

Kananga

Active member
#5
Fuel and foam don't mix.
You could do a lot of it in foam but a 100% foam plane for that weight and torque would surprise me. I'm watching with interest.
 

L Edge

Active member
#7
Bad idea. Looking at it from a safety point, think about this.

A plane that size to handle a 25 cc motor will weigh about 10-14 lbs if made out of foam etc, as you describe and think of the stresses on the plane such as aileron hinges, servos , firewall, etc. and what can happen if it fails.

Add a swinging prop of about 15-17 inches at say 1700 rpms that hits a person, or a severe crash which has gasoline that could cause a nasty fire with a blowing wind on dry grass!!!!! What about the engine crankshaft or muffler whatever when it hits turning at a high rpm?
 

Kananga

Active member
#8
When you say bad idea do you mean the foam part or the engine part?
The engine part is perfectly safe and nothing compared to jets and high nitro engines safety wise. There are liteary thousands and thousands of people flying that type of engine in various types of airframe including myself.

It sort of sounded you were against the idea of using that type of engine but you shouldn't be concerned.
 

L Edge

Active member
#9
When you say bad idea do you mean the foam part or the engine part?
The engine part is perfectly safe and nothing compared to jets and high nitro engines safety wise. There are liteary thousands and thousands of people flying that type of engine in various types of airframe including myself.

It sort of sounded you were against the idea of using that type of engine but you shouldn't be concerned.
Not the engine, but the building the plane made up of the foam that isn't designed right. One mistake, and a person(s) could get hust or worse.
 
#10
Bad idea. Looking at it from a safety point, think about this.

A plane that size to handle a 25 cc motor will weigh about 10-14 lbs if made out of foam etc, as you describe and think of the stresses on the plane such as aileron hinges, servos , firewall, etc. and what can happen if it fails.

Add a swinging prop of about 15-17 inches at say 1700 rpms that hits a person, or a severe crash which has gasoline that could cause a nasty fire with a blowing wind on dry grass!!!!! What about the engine crankshaft or muffler whatever when it hits turning at a high rpm?
That could said of any RC aircraft, LI/PO batteries are a fire Hazzard too. Where I fly I am the only one there and it is all desert.

Casey
 

Bricks

Well-known member
#12
Bad idea. Looking at it from a safety point, think about this.

A plane that size to handle a 25 cc motor will weigh about 10-14 lbs if made out of foam etc, as you describe and think of the stresses on the plane such as aileron hinges, servos , firewall, etc. and what can happen if it fails.

Add a swinging prop of about 15-17 inches at say 1700 rpms that hits a person, or a severe crash which has gasoline that could cause a nasty fire with a blowing wind on dry grass!!!!! What about the engine crankshaft or muffler whatever when it hits turning at a high rpm?
Have you ever been around any gas airplanes you make it sound like it is the end of all. No different then using balsa just foam does not like gasoline there are many foamies made out of foam core that use gasoline or Nitro engines.