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-   -   How to keep weight down. Epoxy or ca (https://www.rcuniverse.com/forum/kit-building-121/7889326-how-keep-weight-down-epoxy-ca.html)

rowdog_14 08-26-2008 07:11 PM

How to keep weight down. Epoxy or ca
 
I am getting another GEE BEE and want to get every oz off of it. I have used epoxy on all my models to glue servo trays, horizontal and vertical stabilizers. Could I use the thick CA or Gorilla Glue instead of epoxy. I think these are lighter. I want to keep the strength of epoxy but the the lightness of CA. Give me some suggestions.

Thanks
Karlston

R8893 08-26-2008 07:33 PM

RE: How to keep weight down. Epoxy or ca
 
Either will work; they have for me. I rarely use epoxy for anything anymore. Except finishing resin and paint.

outdoorhunting 08-27-2008 07:55 AM

RE: How to keep weight down. Epoxy or ca
 
The only thing I use epoxy for is around the firewall. I use fiberglass resin for fuel proofing & a base for paint over balsa. It's cheap, you can mix it to dry slow or fast for each application, & it's very easy to sand !! Oh,yeah, thick CA & always have a fan going !!

cold_reboot 08-27-2008 08:55 AM

RE: How to keep weight down. Epoxy or ca
 
+1. The only thing I use epoxy on are firewalls, landing gear mounts, elevator and rudder. CA for everything else. Thin CA works great for sheeting, tac it down with Thin then I'll use Medium CA for strength (usually a filet). Medium CA is also gap filling, which is a plus. Makes the building a lot faster since the cure time is so short, but medium, and more so thick, give ample repositioning time should you need it. Thin is pretty much instant as you'd expect.

CrateCruncher 08-27-2008 11:39 AM

RE: How to keep weight down. Epoxy or ca
 
If you look into the cumulative weight contributed by each part of an airplane the weight difference in adhesive is minuscule in comparison to everything else and yet failed joints are one of the leading causes of airplanes being lost. A better place to look is in tires, fuel tank capacity (do you really need a 20 min flight duration?), battery pack size, etc. Many GeeBee fuselages are designed far heavier than they need to be. The inherent rigidity of such a wide and short shape simply doesn't require a multitude of plywood bulkheads and longerons.

That being said, I use Titebond wood glue for most joints because its cheap, lightweight and handles shock better than brittle CA. I still use 30 min epoxy in high stress areas.

rowdog_14 08-27-2008 04:25 PM

RE: How to keep weight down. Epoxy or ca
 
Thanks I was kinda on the same page with CrateCruncher. I will just keep using my epoxy and ca for the hinges. It is a Great Planes so it is pretty much built, I was just trying to save a few oz when installing the rudder, the elevator, and the cowl tabs.

Thanks everybody.

Gray Beard 08-27-2008 05:48 PM

RE: How to keep weight down. Epoxy or ca
 
Are you talking about an ARF????? When building A kit there are A number of places to get rid of weight and A number of ways to do it. CC is very correct, the glues you use are not the place to save weight. Some of the glues like Gorilla are about the same weight anyway. Once covered you are limited to what you can do.

rowdog_14 08-27-2008 08:44 PM

RE: How to keep weight down. Epoxy or ca
 
I have are already answered your question before you asked it :)

jaka 08-28-2008 03:21 PM

RE: How to keep weight down. Epoxy or ca
 
Hi!
I seldom use epoxy glue. Use Flash Ca glue on firewalls and every thing else . Fly pylon racing and scale.

OffroadBEAR 08-28-2008 06:28 PM

RE: How to keep weight down. Epoxy or ca
 
I would recommend using epoxy for the stabs an cowl tabs. The cowl tabs will see a lot of vibration, and the stabs are not an area you want to worry about and think, "I hope that stuff'll hold." IMHO, its worth the fraction of an ounce weight penalty for piece of mind. Being an ARF, the best way to cut weight is in the components.

BTW, the reason gray beard asked if it was an ARF is because this is the kit forum, and it wasn't clear that you were referring to an ARF. :)

fairplane 08-28-2008 09:32 PM

RE: How to keep weight down. Epoxy or ca
 
My sig kadet mkII just went out of control 2wks ago-the servo tray was CA'd in and came away from the fuse-I would use epoxy/did to repair the servo tray mount. Luckily the plane went down in a tall canola field and there was no damage-my 2 cents

pauser98 09-07-2008 11:43 PM

RE: How to keep weight down. Epoxy or ca
 
I use epoxy for places where some time is needed for alignment and adjustment. Like stab, tail fin and joining the two wing halfs.

Chris


submikester 09-08-2008 12:31 AM

RE: How to keep weight down. Epoxy or ca
 
2 oz of epoxy weighs the same as 2 oz of CA. Do you really use less of one glue over another? I have been using tite bond a bit more lately and certainly don't think I use less glue with it. Probably a bit more in fact, it's cheaper so I don't tend to be stingy. Epoxy isn't something I use in everyday building - just in certain parts which require less rigidity, strength, flex or fuel proofing. Firewalls, landing gear blocks, tail assembly, various mounting points...etc.

bajajrider 09-09-2008 05:33 PM

RE: How to keep weight down. Epoxy or ca
 
try out locktite 'sumo' glue. its a poly glue like 'gorilla', but it foams 50-60% less, and dries translucent white.
easier to cut away after dried too.

i also only use epoxy(thinned) for fuel proofing, or mixed w/micro ballons for fillets.

i glue 90% of my planes stabs with thin ca, if you have a tight joint it will bond very well.
(a tight butt joint glued with thin ca is stronger than a joint with gaps glued with epoxy/thick ca)

dbacque 09-09-2008 08:52 PM

RE: How to keep weight down. Epoxy or ca
 
It's not the type of glue, it's the quality of the joint. Make every joint fit as tightly as possible and you'll use less of whatever glue you use.

Filling gaps with either epoxy or thick CA is a no-no. Balsa is lighter than either one. A good tight fit means you use a very thin layer of glue and you can use whichever glue you need for the particular application.

A gob of epoxy isn't the way to get a servo rail to stay in place. A carefully cut balsa gusset with a thin film of epoxy, CA, aliphatic resin, Ambroid or whatever will be lighter and stronger. Firewalls? I use nothing but epoxy but with a good tight fit and balsa triangle stock to increase gluing area. Tail surfaces, actually I've changed to using mostly CA here and have never had a failure.

Dave

andrew66 09-09-2008 09:56 PM

RE: How to keep weight down. Epoxy or ca
 
another thing you could do, is replace some of the light ply with balsa. in the scratch build that im doing, the plans call for 1/8 lite ply or 3/16 balsa for the formers. im using balsa, which is lighter, and plenty strong enough. build light to fly, not strong to crash!
whatever way u go, i hope the best of luck,
andrew

dbacque 09-09-2008 11:17 PM

RE: How to keep weight down. Epoxy or ca
 
The 1/2A plane I'm currently scratch building has numerous parts made from light weight contest balsa with a skin of 1/32" ply. Put the strength where you need it.

Dave


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