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Old Jan 20, 2015, 02:55 AM
Capt K. Lee
Joined Feb 2014
7 Posts
Discussion
Spars surface or drilled

My question is "Is it better to dig out a section of aircraft to place a strengthening carbon fiber spar or to drill out a precise directional hole and epoxy a carbon fiber rod into place." This is based on the premise of crash proofing your aircraft.

I severely damaged my cowling on an Apprentice. I used the advice of strengthening the next one with duct tape and have smashed it several times with nary a crack. Now, I'm looking at placing carbon fiber rods in my larger aircraft. I've seen the rods on the Apprentice under the horizontal stabilizers and those placed throughout other aircraft glued directly in the wing. So, is it worth the time and effort to surface epoxy or take the time and extreme effort to drill into the aircraft to hide the rod and give proportional strength to both sides?
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Old Jan 20, 2015, 07:01 AM
Da' Cajun
Boogie_'s Avatar
Lake Charles, Louisiana
Joined Jun 2009
3,009 Posts
Assuming you're talking about foam planes....

If your goal is aesthetics then drill a hole.
For ease of installation cut out a slot and install them flush with the surface.
Or, use flat carbon sticks and make a slit with a razor knife (exacto).
I prefer GG over exopy for stuff like this.

That said, the best solution is to not crash.
No sarcasm intended.

Improving your piloting skills is the best way to "crash proof" your planes.
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Old Jan 20, 2015, 08:13 AM
Registered User
United Kingdom, Scotland, Killearn
Joined Aug 2014
182 Posts
I think you are maybe referring to a video I have seen where the presenter shows how he drills through a wing section accurately. I tend to think that if you insert a spar into a long hole like that it is going to be very difficult to get adhesion along its length.

My own preference is for cutting a slot in depron or foam, taping up the margins (and behind if the slot goes all the way through). Lay epoxy into the trough, press in the spar and fill the rest of the slot with epoxy, spreading it flush with a spatula. Take off the tapes while the epoxy is still green. Very quick and gives a fairly neat finish. I haven't tried GG for this - Boogie - I assume you tape over the slot to prevent foaming out of the slot?

I'm a bit sceptical about the idea that you can crash proof even foam planes. A crash that's heavy enough to take out a wing will have a very good chance of breaking a carbon spar. Indeed, it was fuselages I got through when learning to fly RC.

I'd tend to agree with Julian, that the answer really lies in piloting skills, whether you develop these via a simulator or by regular flying for real. There is a learning curve to be assaulted and, for all but complete naturals, a number of broken airframes and repairs along the way. I bought three of the same model - because they were cheap - and that way I always had one that was ready to fly. It is important to get back on the horse quickly and not to be discouraged. And all of a sudden you will find that you are going home with an intact model more often than not.

Alec
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