I'm getting to the stage when I'll be covering my Tower Trainer 40 soon and I'm not sure about a few things.

First, if I use epoxy to fuelproof the engine area, will film covering stick to it when I overlap the film from the fuse sides on to the epoxied areas?

Secondly, how do I fuel proof the area where the torque rods exit the wing? Am I supposed to slide some covering underneath the torque rod? Do I apply some fuel proof dope or polyurethane around them before attempting covering?

Lastly, where I melt/cut away the covering to expose the slots for the CA hinges, is it a good idea to fuel proof these areas too before covering or does the CA take care of that?

Thanks![8D]

First: Cover first, fuel proof second, then the thinned epoxy used for fuelproofing will seal the covering in the engine bay and it'll be strong and nice.

Secondly: I don't fuelproof where the torque rods exit the fuse or around pushrods. The norm is to fuelproof the engine bay and some also do the fueltank area, nothing else. (You wont have fuel gushing all over the plane, only close to the engine and in the line where the muffler spits it out)

Third: Just slit the CA-hinge slot open, insert the hinge and CA them in place, nothing else is needed.

test005 has your answer good luck merry x-mas

Consider buying a product called Balsarite and use it for fuelproofing and to help the covering stick to the wood. I've used this stuff on EVERY plane I have built and the results have been great. Before I begin covering I apply one coat everywhere I want the covering to stick. I also apply 3 to 4 coats on any exposed wood, on areas where the covering seam will be on bare wood, such as the wing saddle area, and in the bottom of the fuel tank compartment. The heat bonds the covering to the Balsarite and the Balsarite protects the wood. I don't see any fuel creep or peeling covering.

Edit: forgot to answer question 2. I sand the pushrod tubing flush with the plane. Since they were glued in with CA, the wood in the area is already fuel proofed. The Balsarite I apply before covering adds a bit more protection and ensures that the covering doesn't peel after I've cut the opening for the pushrod.

Test Pilot, If you don't allready know about these little exhaust deflectors, they're about the best 4 or 5 bucks you'lll ever spend. They work really well at keeping alot of fuel from the pipe off of your plane.

http://www2.towerhobbies.com/cgi-bin...&I=LXD636&P=ML


Test, that sounds like a good idea for an ARF I'm about to do, what do you use to thin your epoxy with? Thanks in advance.


Mark

Mark, there are 3 common choices for thinning epoxy. A little denatured alcohol or acetone works well, but only use a very small amount. One issue with diluting the epoxy is that it will not cure as hard. Another choice, that won't weaken the epoxy when it's cured, is to just heat it up a bit. Note that this will reduce the cure time, so use 30 minute or slower epoxy.

Thanks Chuck, good tip, that sounds simple enough. I just wanna go over the firewall a bit since it is an ARF to make sure it's ok. I think heating up the 30 minute will be the ticket. Thanks again & have a great Christmas!!


Mark

That was too obvious! Silly me.

Thanks for the tip on the Balsarite, Chuck. Sounds like good insurance.

And Mark, I may use one of the deflectors. The muffler on the Evolution .46 has a exhaust that can be aimed in the direction of choice, so I'll wait and see how my plane looks like when it gets down on the ground.

Thanks all for the information.

If you use one of those deflectors, watch that it doesn't reduce your engine's performance. I used one once (Once) and got a severe drop in RPM.

Covering won't stick to epoxy very well (If at all), but I fuel-proof first (With thinned epoxy or Polyurethane) and then (Where the covering ends on epoxy - like in the engine compartment) I'll hit the covering edges with CA

I was worried about interfering with engine performance. Good tip.

Does the covering stick to polyurethane well? I've got almost a gallon of it that is designed for floors and is high gloss.

The covering may stick to polyurethane OK, but that kind of poly may not be fuel proof. Better run a test before putting it on your plane.

I always fuel proof last. I like to do the inside of the fuse where the tank goes and if you fuel proof it before covering it doesn't allow the air to escape as well. Metal handled flux acid brushes work really well and you can bend the handle to get all around the inside of the fuse. I also use black fuel proof dope on my firewalls for a little more finished look.

I like to fuel-proof first so that if an edge of the covering DOES lift up, it won't expose un-treated wood

That's why I'm so sold on Balsarite, it fuel proofs and helps the covering stick better. I even use it to fuel proof bare wood in the engine and fuel tank areas on ARFs.

How about both? Fuel proof the at risk parts of the airframe first with balsarite and then the engine area again later, after covering, with thinned epoxy?

I'm like Minnflyer, I like to fuel proof first and then cover. If the covering lifts then there won't be bare wood exposed. What I do to try and keep the covering from lifting is at the edge where the covering meets the epoxy on the wood I will use a very small amount of epoxy brushed on the edge of the covering to hold it down.

Ken

While you could do this I'm not sure I understand why you'd want to. Balsarite does the fuel proofing for you. I just paint 3 or 4 coats of it in the engine area before covering. I guess you add another coat to the engine area and seams after covering.

Do you have to 'fuel proof' a ARF??

Chuck,
I don't use Balsarite. I use epoxy to fuel proof. I use black primer paint and spray the engine compartment with it, then I will paint the epoxy over that (thinned with heat and not alcohol), and I will paint the epoxy up over the edges of the engine compartment. Then I will apply the covering and overlap the edge of the engine compartment. Then a very small bit of epoxy brushed on the seal down the edge of the covering. I used to use thin CA to tack down the edge of the covering, but I didn't like the way if left a "fog" on the covering (and the fact that I've been trying to phase out using CA anyplace that I can).

ibflying,
Yes, you should fuel proof an ARF too. Any exposed wood needs to be fuel proofed, otherwise you run the risk of the airframe failing. Fuel and exhaust residue will saturate the wood which softens the wood and makes it weak, it also can cause glued joints to fail. In fact, ARF's are sometimes more difficult to fuel proof because you can't also get into the inside of the fuselage to fuel proof it.

I always fuel proof the inside of the area where the fuel tank is inside of the fuselage. I learned to do this the hard way. I had an Ultra Sport 60 that had developed a fuel leak inside the fuselage. The fuel soaked into the wood of the fuselage and the F2 former. This former is where the front of the wing is held in place with. The fuel caused the glue to fail on the joint between the former and the fuselage, and the former pulled out while doing an outside loop. The fuselage and wing went two different directions, the fuselage becoming a lawn dart and the wing gracefully fluttering back down to the ground. In fact, I still have that wing as it wasn't damaged coming down, didn't even break the monokote!!!!

Hope this helps

Ken

I've been flying electrics for two years. You don't get much residue on those planes, so I guess I'm a little paranoid, this being my first glow plane.

Do you cover the engine area as well too? I was thinking similar to RC Ken and fuelproofing the engine area with balsarite, then putting the covering down on the plane (not engine area) and then brushing on epoxy on the areas left exposed as final insurance.

There is often more than one way to accomplish the same thing. I've been using just Balsarite in the engine area for a long time and it has worked well. I don't coat the Balsarite with anything, it's already fuel proof. Ken described the method he uses and that sounds like it works well too.

Just to clarify what Ken said, An ARF should already be fuel-proofed. But they will generally do the engine compartment and not the tank area. Doing the tank area is not critical, unless you have a leak - Then you'll really wish that you had fuel-proofed it!

"Should" being the key word. Unfortunately, it seems that I've ended up with more that were not fuel proofed, even in the engine compartment, than were. Sounds like you've been assembling better ARFs than me.