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| Giant Scale Aircraft Discuss Giant RC Scale Aircraft. |
Topic Review (Newest First)
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| 10-13-2011 06:56 AM | ||||
| bradleyban |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Ive seen gorilla glue hold a propellor blade on a PZ Stryker. Like one blade was physicly broken off and glued back on. I wouldn't have had the balls to do it but I saw it done and it held for a day of flying. I was some scared let me tell ya. |
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| 10-13-2011 06:52 AM | ||||
| TBrum |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Quote:
I've seen that done before also Jim - that's why I stood on that wing in the video - it should have held no problem. In fact, to your point, both myself and Jack M should have been able to get up on that wing without a problem. I don't have an explanation for what happened  Even on my Ultralight 40% Ferrari Edge or Wingburners's 35% E330 (both with the insanely cores wing cores), I wouldn't have been afraid to do that! I'm baffled about what happened???? |
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| 10-13-2011 06:49 AM | ||||
| Bdegan |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Hi Jim, I have noticed the same about the Polyurethane glues as well. BUT......... Its only the glue that is allowed to expand and swell and fill with air that gets soft and easy to break. The Poly glue that is kept compressed and not allowed to expand, dries as hard as Epoxy. What you don't see when you do hinges is the glue that remains trapped in between the Robart hinge pin and the wood. Yes some expands and seeps out. But what does remain trapped inside doesn't get to expand like what you see on the outside and is very hard. Thats why all the weight is needed when sheeting foam cores using Urethane glues. It holds the sheeting down against the foam and doesn't allow the glue to expand. Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free! |
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| 10-13-2011 06:35 AM | ||||
| scaleguy |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Quote:
What was used to attch sheeting to cores, gorilla glue or epoxy? A few years back I was at a IMAC contest in Lansing MI and on Sunday a guy stopped by on his way home after crashing a 40% Carden 300 somewhere else. He stopped by just to visit but after the contest he took out the only surviving intact wing pannel and placed the root on a bleacher seat about 9" off the ground and the wingtip was resting on the ground. The builder wanted to demonstrate how tough his wing was. Cam is a BIG guy pushing about 250lbs he was able to stand on the wing up neer the root and the wing flexed, a little but did not break. The pilot, about 160lbs, got up on the wing as well, standing right beside Cam so his one foot was on the other side of the end of the wing tube probably about 16" from the tip. Again the wing flexed a little more but did not break. They started jumping up and down on the wing and after the third jump the wing finnally broke about 2/3rds of the way out. Cam uses epoxy and vacuum bags his wings. I don't know if he does any extra reinforcement but that demo was pretty impressive and that was about 6 years ago. While gorilla glue seems to really grip it is more brittle then epoxy. this is evident every time I use it to glue hinges in. It does not take much force to break away the overflow glue that oozes out of the hinge pocket when doing robbart style pin hinges. Just some food for thought. |
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| 10-12-2011 03:29 PM | ||||
| bradleyban |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Quote:
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| 10-12-2011 03:00 PM | ||||
| TBrum |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Quote:
I checked on the current 43% that I'm building... each wing is 57" long, the phenolic tube goes into the wing only 17" and the 12" balsa spar (top and bottom) is 5" over the tube and 7" extension towards the tip. So, on a 57" wing, only 24" is reinforced. Talking with Dennis, due to the chord design, 50% of the load is supported, aerodynamically by the first 25% of the root of the wing - so 0.25 x 57 = 14". The load drops off exponentially from 14" out. Dennis doesn't know what happened either, but, based on the photos, it was built correctly. The only thing could be sheeting thickness??? (I find it hard to believe though - the sheeting seemed lots thick enough at the fracture)... the strength of the wing is all in the sheeting and strength decreases drastically as thickness is reduced. Dennis has never seen this before and I wasn't even beating on it hard, so it's a true mystery!!! To be safe, from now on, I will also reinforce top and bottom of the cores with Carbon Fiber to be 110% sure that I'll never have a failure!! Cheers Trevor |
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| 10-12-2011 12:41 PM | ||||
| bradleyban |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Sounds fishy to me. Seems wierd that there is no spar from the break point out towards the tip. Theres still alot of wing there that need to be supported |
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| 10-11-2011 05:33 AM | ||||
| TBrum |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Good News and Bad News!!!..... . . . The Good:The builder of this 43% Extra 300 sent me pictures of the construction! - the attached pictures clearly shows that the hard balsa spar extension was installed correctly and based on the placement in the picture, it was installed in the correct position (~6" over the tube phenolic & ~6" overhang in the foam towards the wingtip).  When Jack Marcotte and I did the inspection at the feild of the wing cross-section, it was clear that the spars were present only on the root-side of the break, but not on the tip-side of the break, so we were correct to conclude that the wing failed right after the spar extensions. When I started digging into the foam towards the root, I hit hard material about 2" under the overhang of the balsa spars, which I assumed was the wingtube block and therefore assumed the spars were incorrectly placed - looks like it must have been some hardened Ultimate glue that penetrated into the foam?? . . . The Bad: Through some analysis of the attached video and comparison to the attached photo, it is clear that the wing folded just past the end of the balsa spars, which were installed correctly???? I called Dennis about it and Dennis has never seen such a thing either??? We still have no idea why this happened, since it was built correctly???? . . . The only thing we can think of is that perhaps the balsa skins were exceptionally thin in the area of the failure or perhaps there was a flaw in the sheeting in this area, but we will unfortunately never know! From now on, for peice of mind, to prevent this from ever happening in the future, I will always be reinforcing the wings with strips of Carbon Fiber - top and bottom
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| 09-13-2011 07:27 PM | ||||
| Jack Marcotte |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Quote:
lets try it again
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| 09-12-2011 09:55 PM | ||||
| TBrum |
Re: 43% Carden Ferrari BBT Extra300 / ZDZ180 Quote:
I'll test the Moki soon, but so far this explains the problems!! T |
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