I'm rebuilding my GP trainer 40. I noticed the wing saddles do not seal around the wing very good. There are gaps in certain places that are fairly large. How do i form the saddles to fit better?

Well Ive done it 2 ways. On my 4 *60 i took a piece of triangle balsa stock, wet it down real good and with the wing in place pinned the the balsa to the fuselage forming a fillet between the fuse and the wing. leave it there until dry then glue in place. Use syran wrap to keep the water off of the wing. while it dries.
The second way is to go ahead and cover the aircraft, wrap the wing in syran wrap. the put a bead of aquirium sealant on the fuse and bolt the wing in place. let dry 24 hours. then cut the access sealant off the fuse thus fills the gap the sealant is fuel proof and lasts a long time. just use caution you dont get the sealant where you dont want it.
gtood luck

Hi:
Yep, the sealant method is simple and it works great. Only, instead of aquarium sealant which may be hard to come by, use simple silican bathtub sealant found at Home Depot or Lowe's or your local hardware store.

Here is the routine. Cover the wing center section with saran wrap (or equivalent) holding it in place with masking tape. Get it pretty tight. Then run a rather heavy bead of the sealant along the saddle. Mount the wing and tighten it down being careful to maintain alignment. Let it sit for 24 hours. Then remove the wing, remove the saran wrap, and with a sharp blade cut away the excess sealant (you only have to do the outside unless you are really a neat freak), then go fly!

This stuff really takes heat well. You can use it for gasket material on your engine without worrying about it burning away. I have used it as a gasket between the exhaust port and the muffler without any problem. It lasts for years!

Good luck,
Phil

what i always do when building a kit is attach the wing and then use a cross grain sheet of 1/16 balsa as a guide, wrapping it around the wing and marking the fuselage with a pencil, that'll give me a line exactly 1/16" from the wing surface to the fuselage, i then sand the fuse to that line (don't sand away the line just up to it) then when you finish the covering add 1/16" wing tape for a perfect sealed fit. allot less hassle and mess then the silicone job.

kc

the silicone and saran wrap is the best method to use you dont need any sealing tape at all that does everything at once.and like was said here if you just want to hide the gap to wing then use the triangle stock wet down,that does make the fit look neat.be careful looking for bath tub calk at the hardware store some of that stuff is latex,make sure it says silicone,it even comes in colors so you might find a match to your covering or close.

The silicone method sounds the easiest. I was thinking about using some micro balloons mixed with epoxy, squeeze it between the gaps then let it dry and grind off the excess and that would give me a hard surface that wouldn't flex or come off. Anyone use that method.

RCU member Caffeenman has a great how-to on his website for doing "the perfect" wing saddles. You can find the how-to here:
[link]http://airfieldmodels.com/information_source/how_to_articles_for_model_builders/construction/wing_saddles/index.htm[/link]

Hope this helps

Ken

I haven't done the epoxy thing, however I do use balsa filler with saran wrap to "true up" the wing saddles prior to covering. Covering OR paint will not adhere to the silicone.

Here is an old school technique.
Set the wing on the table and brace it up at 0-0.
Set the fuselage over the wing and brace it up at 0-0.
Scribe a line on the side of the fuselage that matches the wing.
Don't sand to the line, just use the line as a reference.
Sand the saddle until it matches the scribed line just above it.

Thanks RCKen,

That article is just what i was thinking about. It shows all the steps i need. I will definately try that method. You always seem to be a great wealth of good info.

skeeter

I've used the 'perfect fit' like shown by PilotFighter and the epoxy/micro balloons method, and on a 2 stroke (and most 4 bangers too) glow engines the oil still gets between the wing and the fuse, the wing tape seals that and will NOT allow any oil residue in at all (even on 150+ mph planes) and the wing tape takes a whole 30 seconds to install on both sides, and NO MESS so you don't have to wait long hours while silicone cures and you don't have silicone all over the place. I've seen the silicone used by allot of people and it's just not visually appealing at all to me, i guess if they'd of took the time for the perfect fit then used it, it might of had a better outcome but I've yet to see one that way.

kc

kc

i've never had a problem with fuel residue getting into the compartment on this plane, maybe because it's a high winger. It does have large gaps in the saddle though in some spots. I'm talking maybe 1/4" in some places. It was in storage for over 15 yrs and am rebuilding it to start flying again. The rats got to it in a really bad way, but it is starting to shape back up again. Once i finish the recovering i'll be proud to say i built it. Back then they really didn't have many arf options, not that i would have bought one anyway. I like building to much.

KC36330, I hope the tornados that tore through Enterprise missed you. It's on the news right now. If you read this, check in please.

just got power restored, hopefully it'll stay on. I've seen first hand probably 20 tornado's in my lifetime and this was one of the loudest and very near the biggest I've ever seen. i lucked out and only got some tree breakage and wind damage but 2 blocks over it's completely leveled. the news seams to only be showing the high school (which now has confirmed fatalities, 9 as of now) but allot of the rest of town is much worse, i haven't heard if Morgan fuel made it through or not, they've completely sealed off down town and we are as of 5pm local time under curfew. worst part is it's starting to get nasty again, winds picking up and thunder and lightening picking back up.

kc

EDIT: Morgan didn't get much damage so fuel costs should stay the same

Good to hear it pretty much missed you KC. It's sad about those who weren't so lucky. Hopefully the storm will move out of the area now.