Rebuild after a prang...

Grr, I pranged my Mega Mosquito this weekend after many painstaking hours of filling, sanding and priming. I'd like to rebuild the rocket, but the body tube is thoroughly crunched. I had a few ideas in mind for rebuilding the Mosquito, but wanted to get the opinions of a few people who have rebuilt after prangs before I proceed.

Options:
1) Remove fins, motor mount and launch lugs to be reused with a new piece of BT-80. I could use a heat gun to soften the wood glue I used to assemble the rocket, but I suspect the paint will bubble before I get the desired effect. Tearing the tube away from the parts I'm trying to save might be an option, since the tube appears to be a total loss.

2) Cut the tube above the upper launch lug. Use a tube coupler in the lower tube to push out the dents (not as bad in the lower tube as in the removed section) and soak the dents with thin superglue. Then replace the removed upper tube section with a fresh piece of BT-80 and short coupler. Or use one long coupler that will strengthen the damaged lower tube and support the fresh upper tube.

Of the two options, #2 seems like the better route to go. Not sure if I should leave the coupler inside after applying super glue to the dents, or remove it to avoid the weight penalty.

Apologies for the low quality of the photo!

Since the tube is all that's bad, replacing just that would be my way to go. Just cut the tube around the fins and use a Dremel or preferred sanding apparatus, to remove the remaining tube and glue from the fins. You can do the same thing to the motor mount as well. I've tried undenting tubes before but was never happy with the end result. You'll find that either option you choose will take about the same amount of time, so just replace the whole tube. You'll probably wish you had if you don't.

plain old white vinegar will soften glue.
Rex

Option 1 I would call "rebuilding." Option 2 I would call "repairing." Your own choice of thread title say it all: rebuild.

Sorry for the uninformed question: Is "prang" slang for BT damage? Thanks in advance!

I always associate "prang" with a nose-first crash, involving a failure in the deployment of the recovery system - coming in ballistic. Or near ballistic.

75Grandville said:

I always associate "prang" with a nose-first crash, involving a failure in the deployment of the recovery system - coming in ballistic. Or near ballistic.

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Ahh, gotcha', okay, thanks. That makes sense.

and then there is the power prang(usually associated w/ multi-stage rockets) where the rocket comes in ballistic under power.
Rex

Rex R said:

and then there is the power prang(usually associated w/ multi-stage rockets) where the rocket comes in ballistic under power.
Rex

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Oh wow...wow. That would be pretty rough, to say the least. Pretty well total loss.

I pranged one due to low altitude that came in ballistic during the ejection delay. The nose cone buried itself, and a split second later the ejection charge went off, which kicked the rest of the rocket several inches into the air. Despite the pain, it was pretty funny.

jqavins said:

I pranged one due to low altitude that came in ballistic during the ejection delay. The nose cone buried itself, and a split second later the ejection charge went off, which kicked the rest of the rocket several inches into the air. Despite the pain, it was pretty funny.

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Glad you saw the humor in it... makes me not feel so bad chuckling a bit to myself reading it. Sometimes laughing is all you can do...

Funny you should mention it. I also crumpled my Mega Mosquito's main body tube last month.
And I'm facing the same questions you are. I hadn't thought about a stiffening tube or coupling tube until now.
But as the damage doesn't seem to be as bad as yours, I just might remove the inside anchor for the shock cord, and try that.
Anyone know how much a coupling tube for a BT-80 (Mega Mosquite) might run?

Prang...there's a word you don't hear much anymore. I'm not sure when it originally entered modroc usage but it was wildly popular in the 1970s. Apparently originated from old British RAF slang for an aircraft crash, happily stolen by the rocket community.

caveduck said:

Prang...there's a word you don't hear much anymore. I'm not sure when it originally entered modroc usage but it was wildly popular in the 1970s. Apparently originated from old British RAF slang for an aircraft crash, happily stolen by the rocket community.

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I thought it came from the noise a piano made when it fell on Wile E. Coyote.:wink:

Donnie said:

Glad you saw the humor in it... makes me not feel so bad chuckling a bit to myself reading it. Sometimes laughing is all you can do...

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Don't feel bad at all; the humor is why I posted it

Kirk G said:

Funny you should mention it. I also crumpled my Mega Mosquito's main body tube last month.
And I'm facing the same questions you are. I hadn't thought about a stiffening tube or coupling tube until now.
But as the damage doesn't seem to be as bad as yours, I just might remove the inside anchor for the shock cord, and try that.
Anyone know how much a coupling tube for a BT-80 (Mega Mosquite) might run?

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I will likely get my replacement parts thru Balsa machining Service. Standard thin-wall BT-80 is $6 for 34" and couplers are $1 for 4" or $1.50 for 6". The thought of using the motor mount and nose cone to build a Super Big Bertha and ditching the rest has also occurred to me.

Kirk G said:

Funny you should mention it. I also crumpled my Mega Mosquito's main body tube last month.
And I'm facing the same questions you are. I hadn't thought about a stiffening tube or coupling tube until now.
But as the damage doesn't seem to be as bad as yours, I just might remove the inside anchor for the shock cord, and try that.
Anyone know how much a coupling tube for a BT-80 (Mega Mosquite) might run?

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One cheap way might be to contact Lee at Merlin Missiles to see if it's possible to bring one to the next launch.......