brocja01

Hey all, I got my Super Flying Models Super Chipmunk that Hobby Lobby had on its crash sale last week (http://www.mth.com.tw/htms-en/htms/EP15.htm) and I didn't realize it comes with a 300 motor and gear box, but unfortunatly I don't have the money to get into electric this days.

But I do have a Sure Start laying around and I would like to know how I would go about attaching a firewall to foam. The instructions say that when I attach the horizontal stab I need to use 5 minute epoxy, is epoxy good enough to attach the firewall to the foam for the Sure Start?

I thought epoxy would eat the foam. I also realize that I will need to fuel proof the foam, and I know ptulmer gave me some advice on that, but I can't remember the thread in which he gave me product in which to fuel proof the foam with.

Any thoughts would be creatly appreciated.

flyinrog

My Feedback: (1)

There was a thread long ago where we took some of the $3 walmart gliders and whacked off 3 or 4 inches of the nose epoxied on a small piece of plywood and screwed the engine to that and go from there,,no real point to fuel proofing the plane,the styro gets kinda yellowy after a while, but if you try and fuel proof it then it may take a bit longer but would do the same thing plus weigh a little more....Rog

efish

My Feedback: (5)

Hi, I used to fly converted GWS foamies. As flyinrog says, the foam is fuel proof.

What I found was that the planes lasted longer and looked a LOT better if you applied covering film. It really makes clean up (and repairs) so much easier. In fact, my norvel powered Corsair is still flying good.

combatpigg

My Feedback: (3)

I did a drug store foamy with a Norvel .061. Take 1/8" ply and epoxy it to the foam. I tried to help keep the firewall from ripping loose by drilling through the firewall in several places so that bamboo skewers could be glued into the foam, to give the firewall more support. A wrap of 3/4 oz cloth that has been misted with 3M77, then epoxyied to the forward part of the fuselage and edges of the firewall will help keep things attached, especially if you use an electric starter. Gorilla glue, Elmers, or TITEBOND aliphatic glue work OK on foam

Andrew

Bamboo skewers work great with foam. CP's approach adds glueing area and stiffens up the fuselage. Chuck 'em in your drill and drive it in 5" or 6". I really prefer polyurethane glue (I like Elmer's Pro-Bond) to epoxy or TITEBOND since it expands into any open areas between the beads. I drop the skewers in a bowl of water while I'm daubbing up the holes and coating foam.

Skewers are tough and you can buy about 80' of bamboo for a buck.

brocja01

Well after further investigation of the plane. It already has a ply firewall install that the 300 engine and gear was attached to. And it is attached very well to the foam body. I should be able to simply attach the Sure Start without any problems. Now I just need to come up with a way to build out the fire wall to push the Sure Start out away from the fire wall so I can use the cowl that came with the plane. The sure start is much shorter than the electric setup the plane came with.

Any suggestions? I'm figuring I may have to push the engine 1/2 to 3/4 of an inch out. This is just a rough guess.

D Bronk

Brass Tube ,with tiny washers soldered to each end of them to make standoffs.Or epoxy 2 strips of Plywood the thickness of your distance needed, spaced apart, and ,in line with the engine mounting holes..

combatpigg

My Feedback: (3)

I would glue 2 maple blocks to the firewall, leaving a space for the air intake in between the blocks.

brocja01

So maple would be strong enough, and yet light enough not to really throw off the balance of the plane?

gcb

Brocja01,

You are replacing motor and batteries with engine and tank. I would suggest that you check the balance BEFORE permanently installing that stuff. You may have to chop off some fuselage or extend it, etc.

Maple is good. CL flyers use it to mount engines in most cases. Different execution but same use.

Good luck.

George

combatpigg

My Feedback: (3)

Well, Lord only knows how much you need to move the engine forward? If it is 3/4 of an inch or less, there is standard hobby shop maple or even bass stock that will do. If you need to move it up further, then I would go with balsa block to make up some of the distance. Only you can, with the plane in your hands, mock it up and make the final call if it will balance or not, before you commit to gluing the filler material in.