How Does This Happen??? :( - Page 3 - RC Groups
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Jul 07, 2012, 08:14 PM
Registered User
Usually, for the delam part, you can brush on some laminating (i.e. low viscosity) epoxy and let it sit so it can get through the pores and between the foam and the skin. This seems to work for layups that are the least bit dry. Doesn't have to LOOK dry to work. Then, of course, you'll want to wipe off the excess and apply some pressure with a vacuum back or soft foam to hold the kin against the core.
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Jul 08, 2012, 03:17 PM
Do it AGAIN! This time BETTER!
ThermalThief's Avatar

Tip Strike


I would agree tip strike. Didn't have to happen on the last launch could have been prior. Just enough to partially delam the carbon dbox...do a couple more launches and then boom!

Mine is repaired and has since been flown ballasted in 20+ winds.

Good luck on your repair.

Ken
Jul 08, 2012, 05:01 PM
Registered User
I have seen the same damage on a Topsky 2. A friend of mine was launching, and I was watching to analyze his tosses.
That was no tipstrike at all. It was a pretty hard launch, but nothing exeptional.
That plane had internal topdrive, so we blamed it on the hole in the foam, but the delam started at the LE, so we were never really sure.
I had a Binary3 some years ago, and that one also sufferd from delams in the outer wing. It din`t brake, but i still had to fix it after every other flight That wing had a really dry layup. I try to throw perfectly level, keep my shoulder loose and let the plane steer my arm rather then the opposite, so I won`t tipstrike.
If you are absolutly sure that you didn`t hit the ground, contact the vendor and complain.
Jul 08, 2012, 05:17 PM
Registered User
Quote:
Originally Posted by Bad scientist
I have seen the same damage on a Topsky 2. A friend of mine was launching, and I was watching to analyze his tosses.
That was no tipstrike at all. It was a pretty hard launch, but nothing exeptional.
That plane had internal topdrive, so we blamed it on the hole in the foam, but the delam started at the LE, so we were never really sure.
I had a Binary3 some years ago, and that one also sufferd from delams in the outer wing. It din`t brake, but i still had to fix it after every other flight That wing had a really dry layup. I try to throw perfectly level, keep my shoulder loose and let the plane steer my arm rather then the opposite, so I won`t tipstrike.
If you are absolutly sure that you didn`t hit the ground, contact the vendor and complain.
Well I am 99% absolutely sure. But there are many experienced guys in here that swear it just have been a tip strike.... This has got me rethinking. But its just the fact that I was purposely working on form, and that form doesn't get me anywhere close to the ground..... And the fact she has been my baby and I have been extra careful with stuff like tip strikes. Or less than perfect landings....

As for contacting the vendor I kind of gave up on that idea, simply because if 99% of the people here believe its a tipstrike, what will the vendor think?

Oh well.... It's pretty much fixed, it was just very hard to get epoxy actually into the crack. Even thinned out epoxy doesn't move through a hypodermic needle very well.
Jul 09, 2012, 12:15 AM
Registered User
What epoxy are you using, how much and what thinner and what is the hypo needle number?

I use the hypo for injecting thin epoxy and have no problem. I'll check on my hypo needles in the morning.

Gary
Jul 09, 2012, 02:37 AM
Registered User
It was the only one that walgreens had for "diabetics" its 29 gauge, 1/2" length. And I used west systems with 206 slow hardner. Mixed with about 10-15% denatured alcohol. I don't feel like I got a sufficient amount in there, there were also a few bubbles of skin afterwards, in which thin ca injected with a needle worked. Today I tested the wing under stress and didn't see any raising of the skin as it would when it is separated. I also went and flew for about 30 minutes with some mid power throws. It seems to work fine but I would like to inject a little extra epoxy if I can find a way to insure strength
Jul 09, 2012, 02:40 AM
ThomasLee's Avatar
I hope that was foam-safe CA... regular CA will eat away the XPS foam found in most bagged wings

Glad it's up in the air again though! phew! I bet you missed flying during this week
Latest blog entry: Vibe Assembly Instructions
Jul 09, 2012, 02:46 AM
Registered User
I used walgreens superglue!

Lol just kidding... Of course I used foam safe!
Jul 09, 2012, 02:58 AM
ThomasLee's Avatar
phew!
where did you find the super-thin foam safe? I've been trying to find some but wasn't able to
Latest blog entry: Vibe Assembly Instructions
Jul 09, 2012, 03:25 AM
Registered User
My LHS. They actually aren't so great for 80% of the stuff you normally need, but they do have some good scratch building supplies!
Jul 09, 2012, 06:25 AM
Registered User
FWIW There does appear to be a stress riser there judging from the two wings posted in this thread. Whats with that? Topsky should consider a doubler spanning out from the root. If it hadnt failed there perhaps the tips would have shown a mark. Just sayin
Jul 09, 2012, 03:45 PM
God Created me to Create
The_Builder's Avatar
Just to maybe put your mind to rest a bit, a tip strike will on occassion not cause a problem immediately. As someone who regularly destroys airplanes I have had ample opportunities to see how things react. The foam that is used in most bagged wings does not bond to the skins really well. I mention this because you could have hit the tip on another occasion and that got things in motion. Once there is even a small delam started it WILL spread if not addressed. They can be very hard to detect under a carbon D-Box because the D-Box is fairly stiff and opaque. You mentioned the red dirt, we have the same stuff here. There ius a very good chance it would not mark a wing tip because they simply are not porous enough to absord any of it.

Maybe that will ease the sting a little to know that it may not have happened right then and there when you were focussing on form.

Paul
Jul 09, 2012, 07:55 PM
Build something.
Nodd's Avatar
Quote:
Originally Posted by The_Builder
...Once there is even a small delam started it WILL spread if not addressed....
Ahh yes I'm sure he'll sleep well now.
Jul 09, 2012, 08:29 PM
God Created me to Create
The_Builder's Avatar
Quote:
Originally Posted by Nodd
Ahh yes I'm sure he'll sleep well now.
My point is to quit replaying that day in his head, it could have happened any time...

I did a little looking at your Balsa build, very nice!!
Jul 09, 2012, 09:30 PM
Build something.
Nodd's Avatar
Yeah sorry just busting your ballz. Glad you liked my build, I see you're big into the DLG scene, nice work on the Katana stuff.

Anyway don't want to stray off topic here. Great to hear our injured bird is back in the air. That was a quick mend.


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