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Old Oct 12, 2003, 09:34 PM
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GAANDAHL's Avatar
Red Wing, MN
Joined Aug 2000
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Mig 29 becomes arrow

I finally got my Mig 29 airborne today – briefly. I apparently overdid the tension on the bungee, and it left my ramp like an arrow from a hunting bow. Although I had done my best to set it up straight and true, apparently some trim was required as it was rolling to the right. I couldn’t overcome the roll before it hit, embedded up to the canopy in soft dirt. The left wing was knocked loose and the battery mashed a couple of formers.
Question of repair: with the short wingspan and reasonable root area I’m tempted to try epoxy on the wing/fuse joint followed by some fiberglass reinforcement around the repair, but without the surgery required to splice the spar. I haven’t repaired an EDF yet, would that approach underestimate the stresses on the plane?
Thanks,
George
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Old Oct 12, 2003, 09:36 PM
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Red Wing, MN
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Now the Mystery

I heard a “TING” sound as it came off the bungee, just before I cranked up the motor. The spinner is missing , but the screw that holds it on is still there. I’m guessing it was cracked by my bungee’s towhook, and flew apart when I started the motor. Would I be giving up significant thrust by operating without it? If so, who is likely to carry parts in the US? Thanks for any comments.
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Old Oct 12, 2003, 10:02 PM
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Stavanger, Norway
Joined Feb 2000
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ooh sorry to see that

Spinner probably came off due to too much tension, cracked and the rpm took it off. You'll probably see very little loss by flying without.

I think you can use epoxy/glass as you suggested for repairs, if you can add a part joiner even better. A 3-4" long 1/8" ply rib epoxied next to the spar will do nicely.
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Old Oct 12, 2003, 10:48 PM
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Red Wing, MN
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Thanks Haldor, there's nothing that can beat hearing from the designer! By the way, I was really impressed at the relative lack of damage from a pretty tough hit. Good design work! I'll start repairs next weekend.
Best,
George
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Old Oct 13, 2003, 12:48 AM
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Stavanger, Norway
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Good to hear damage was minimal considering the impact. It wasnt designed for crashing though so stop it would ya?
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Old Oct 13, 2003, 01:18 AM
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Las Vegas, NV
Joined Dec 1996
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Things happen so quick on a bungee, it's hard to react in time, especialy on a new airplane. That's why I like 90mm fan sized ROG birds with retracts. They're an important part of a balanced breakfast
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Old Oct 13, 2003, 09:53 AM
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Robert Belluomini's Avatar
United States, KY, Crestview Hills
Joined Dec 2000
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Re: Now the Mystery

Quote:
Originally posted by GAANDAHL
I heard a “TING” sound as it came off the bungee, just before I cranked up the motor. The spinner is missing , but the screw that holds it on is still there. I’m guessing it was cracked by my bungee’s towhook, and flew apart when I started the motor. Would I be giving up significant thrust by operating without it? If so, who is likely to carry parts in the US? Thanks for any comments.
I have extra cones that you are welcome to.
Bob
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Old Oct 13, 2003, 03:16 PM
Wof
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How long was the bungee at full stretch ?
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Old Oct 13, 2003, 07:52 PM
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Red Wing, MN
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Bob,
Thanks, I'll contact you off-line in a few days.

Wof,
It was 25 feet from the front of the ramp to the bungee stake. However the bungee was doubled over to effectively give 2 strands. It was off-scale on my fish scale. I was shooting for 13-15 lb, but probably had something closer to 20 lb. Whoosh!
George
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Old Oct 13, 2003, 07:54 PM
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Red Wing, MN
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Oops - make that 25 yards.
George
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Old Oct 14, 2003, 02:02 AM
Wof
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London Southend, Great Britain (UK)
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I am new to this bungee stuff i know there are enough threads to fill a book on the subject, i have only launched by bungee three times so i am no expert my one was only 12-15 metres long at full stretch.

Perhaps it may have been to short but i wanted to get it of that hook ASAP, seemed to work ok like yours it was doubled up pulled back until it felt right.

I might have just been lucky though
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Old Oct 14, 2003, 05:28 AM
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Red Wing, MN
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When I used it on the T-33 it was not doubled over and the plane stayed on the line for quite a distance. The launches had ample power but not so violent. On that setup I was pulling about 8 lb.
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Old Oct 14, 2003, 07:17 AM
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Stavanger, Norway
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Quote:
Originally posted by GAANDAHL
When I used it on the T-33 it was not doubled over and the plane stayed on the line for quite a distance. The launches had ample power but not so violent. On that setup I was pulling about 8 lb.
I'm 100% confident that thats all the MiG needs.
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Old Oct 15, 2003, 08:45 PM
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Red Wing, MN
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Thanks Haldor. Just before I made this attempt I changed my towhook location to that recommended by Trond (and I could tell it is a better position even during this brief launch). After repair I'll reduce tension and go again.
George
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Old Oct 16, 2003, 02:12 AM
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Trondelag, Norway
Joined Mar 2003
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Sorry about the mishap
I stretch mine to 12 lb with a simple fishing scale and seems to work well. Which rubber do you use?

Trond
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