Hey guys

My last ARF lasted a while but it's demise was due to fuel/oil soaking through the covering joins.

I'm assembling my next ARF and want to seal the seams properly, whats the best way to do it? I'll go over it all with the iron, but have heard of using CA. I'm worried the CA will look terrible though, what are your tips? Can i wipe the excess CA off with acetone or something and still have a good finish? Or is there a better way?

The aircraft is a Sebart Su29 50e with a glow conversion and a Saito 91 - should be great!

Cheers

Mark

Mark,

Take the time to clean the plane thoroughly after each session. Also, buy exhaust diverters to keep as much of the exhaust off the plane as possible. If possible, mount the engine with the cylinder at the 7 o'clock position so the muffler is on the bottom and use the diverter.

Planes last a lot longer when they are not in an oil spray all the time.

CA will make a mess and cannot be removed with acetone. Seal the seams well with your covering iron and wipe the plane off regularly, even between flites if you have areas that get oil soaked.

Ditto.

Makes no difference what you do to the seams if you don't clean the oil off it will soak through the covering. The very best you can do you will still have some oil get through. Comes with the territory.

I make my seams usually 1/2" and iron down fully... cleaning, etc after flights and no issues thgugh my planes don't sit all day at the field either... i'm in and out usually in a couple hours.... busy busy busy  []
Mike

ARF covering schemes are nice-n-pretty. The few that I've looked at closely have a base covering (like white) with plenty of eye catching trim pieces in 3 or more colors. The trim pieces are simply low-heated during application so that that stay put. Nice eye candy. They can easily be pulled off by tugging on a loose tip or corner leaving little or no adhesive on the base.

Protect the covering & seams by (re)ironing the trim and seams with a hot iron. Hot is kinda nebulous because it depends on the covering. Hanger 9 uses Ultracote. Hot for Ultracote is 270 - 300 degrees or set your small trim iron to HI temp. The color of the covering will initially darken then lighten when it cools. Once you do this to a trim piece it won't be coming up easily any time soon.

Note: I use Ultracote exclusively so I'm hopin' that others with experience with other brands of covering can chime in on what an appropriate HOT temp is.

Also, I have violated some pretty basic covering "overlapping" rules. Rather than leave the edges to be ravaged by fuel spooge moving from the front to back  I cover the forward exposed edges with Ultracote clear - a really really light covering. I put it down with a LOW heat trim iron then come back with a mid range iron 'cause 270 degrees may easily ruin this stuff.

Then of course you could convert to electric - then this is a moot point.

TTFN,

It;s also a good idea when covering from scratch to have "all seams" facing away from the airflow... This takes some planning... especially on the wing but it can be done...

For example.. I cover the bottom first.. then the top piec will roll over the leading edge  top and back under the bottom such that the seem is facing away from the motor.  On the back side.. you would need to roll the bottom up and over the trailing edge. and let the top piece lay on top of it again so the seam is facing away from the motor.  On the fuse.. all seams are facing downward.. start at bottom , then sides. .then top.  Seams blend in more as well this way. I only try to use ultracote as it;s thinner with no reduction in strenght that I can tell.. and the seam "bump" is almost non-existent.

You need to find the root cause as to why it is immersed in so much fuel and oil that it seeps into the wood in the first place. Tank leak? Hole in a fuel line? Loose covering in the exhaust stream? It should not require added sealing beyond a proper 1/8" covering overlap seam and a wipe-off with a rag or paper towel after flying (Windex or other mild cleaner a big plus). You do also want to fuelproof the interior fuselage around the tank and firewall and outside in the engine compartment. Either with thinned epoxy or a canned poly wood finish.

Thanks for the advice guys!

I haven't been right into the building for a while and so am only talking about ARFs. The last model's engine has shot bearings and pumps out some serious black oil from the exhaust. Bonus about that is I can see exactly where the oil is to clean it up! I always cleaned it with windex though, after every flight and then more thoroughly at the end of the day. The covering still ended up lifting though and oil got to the wood. Mind you I'm talking about over a three year period.

I've mounted the engine inverted and have a pitts muffler for it, so the exhaust should be directed away from most of the aircraft. I've gone over all the seams with the iron and was advised to run a bead of estapol along them, which should dry clear.

I'm in the process of sealing the engine bay now with epoxy... you mention thinning it down which I hadn't planned on. Do you just thin it with Methalated Spirits?

Cheers again

Mark

I thin my epoxy with a small amount of isopropyl alcohol but not the 70% stuff. Wal-Mart sells 91% for a few pennys more and it works better with the lower water content. Don't use too much-just enough to make it easily brushable. As someone mentioned, do all the exposed bare wood areas around the firewall and fuel tank compartment.

Dont use windex to clean your planes if the covering is Monocoat because the amonia will disolve the covering adhesive and cause it to lift. I use alcohol based windshield washer fluid to clean my planes and it works great. I have also had good luck using Fantastic when I get some really tough stains that the alcohol won't take care of.

The simplest way to thin epoxy is to warm it. A heat gun, or even a hair dryer, will have it flowing like water in a few seconds. This does make it 'set' faster so use 30 minute (45 if you have it) epoxy.

Methylated Spirits will work. You need very little.

Acetone, if you have some, is an epoxy thiner. You need very little.

Carrell

I've used Top Flite Monokote Trim solvent to seal seams and it works great. Apply it with a fine modelers paint brush.

FWIW, Nitromethane will dissolve CA's. They're a poor choice where there's any exposure to raw fuel.

ARTF covering just does not last - or few last long, even if you seal the seams - been there, done it, got the T-shirt.

If I doget adecent ARTF, I will fly it first to see if it is worth while spending more money on. If it is a really exceptionally good flyer, I will strip it down and cover it with Oratex or Solartex and spray it with thin coats of automotive K-2 paint. This seals the plane allover, making it 100% fuel proof.I have planes done this way that is 15 years old and still not affected by fuel soaking.

A 2m roll of Oratex is the same weight as Oracover (I have weighed both recently), so it is the weight of paint extra.

You can spray colour matched K2 paint over Oracover to seal the seams.

However both the above procedures may not be everybody's cup of tea for it is time consuming and expensive... but worth while ?YES

Does that Monocoat Trim Solvent really work to seal leading edges? Can anyone else confirm?

I use Monokote trim solvent on all my planes to seal the edges after covering. I also use it instead of heat to adhere pinstriping and other small trim pieces. I have never had a problem with adhesion. I have not tried it with brands other than Monokote.
Chris

On the chinesee arf's the ones not covered with monokote or ultracoat/ ust the kb expoxy thinned down. brush it over the seams. i believe kb expoxie doesnt yellow as it ages. other will
hope that helps

Exactly! Every year I retack the seams with the iron just to be safe. Plus the wife complains when I bring a dirty oil dripping plane in the house. Besides, it's a good habit keeping my plane super clean when I'm done flying.


Pete