[F-FT] Straightening Alpha-III fin can

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David Erbas-White - 30 Jan 2005 16:20 GMT

I have a couple of Alpha-III kits for use with student groups. They
have the orange fin can, but these were apparently stored in such a way
that the fins are significantly warped. Does anyone have any
suggestions for how to 're-warp' these plastic cans back into place?
Some temperature to store them at, then clamping or something similar?

David Erbas-White

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Kevin Trojanowski - 30 Jan 2005 17:07 GMT

> I have a couple of Alpha-III kits for use with student groups. They
> have the orange fin can, but these were apparently stored in such a way
> that the fins are significantly warped. Does anyone have any
> suggestions for how to 're-warp' these plastic cans back into place?
> Some temperature to store them at, then clamping or something similar?

I can't tell you how to straighten them, but I have seen them fly just
fine with warped fins.

-Kevin

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randyolb@charter.net - 30 Jan 2005 17:45 GMT

That's frustrating and all too common. I can't tell you how many times in
the last 36 years that I've opened kits to find the main bt or other parts
very oval, wavy or crimped. Ususally it was packed wrong at the factory, not
from shipping or handling. I have a 2156 Saturn V kit I had to use for spare
parts for the other 3 we regularly fly.

Anyway, the Alpha's fins are thin enough that you should be able to reshape
them. I'd suggest warming them slowly with a blow dryer ( low heat ) and try
to manually bend them back into shape.

Are they warped beginning from the bt, or in the middle of the fins? If the
warp begins at the bt, it will be easier than if they're warped in the
middle.

Randy

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Bob Kaplow - 31 Jan 2005 02:51 GMT

> Anyway, the Alpha's fins are thin enough that you should be able to reshape
> them. I'd suggest warming them slowly with a blow dryer ( low heat ) and try
> to manually bend them back into shape.

That's about what I was going to suggest. Sometimes these are soft enough
that they can just be gently bent back by hand without any heat.

    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"
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Fred Shecter - 30 Jan 2005 18:21 GMT

Extremely common. Heat fins (blow dryer or equivalent) and gently bend back
to shape. Just like sheetmetal, there will be "springback", so go a bit
beyond straight as you bend.

It's annoying when two fins are bent in such a way that they act like huge
flaps and make the model go unstable. If all are bent in the same (cw/ccw)
direction, you get spin and it's not so bad.

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>I have a couple of Alpha-III kits for use with student groups. They have
>the orange fin can, but these were apparently stored in such a way that the
[quoted text clipped - 3 lines]
>
> David Erbas-White

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Model Forum / General / Rockets / January 2005

[F-FT] Straightening Alpha-III fin can