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  #1  
Old 07-23-2016, 09:00 PM
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Default Super Big Bertha epiphany

Today I was gathering the parts necessary to clone the Super Big Bertha, but then I looked again at the 1993 catalog and realized the SBB had an OD of 2.56" and not 2.80" (as I'd always thought.) Therefore, my PNC80B nose cone isn't the right size--unless I upscale the SBB even more.

My question is: what nose cone DID the Super Big Bertha use?

Thanks.
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Old 07-23-2016, 09:06 PM
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Quote:
Originally Posted by jeffyjeep
Today I was gathering the parts necessary to clone the Super Big Bertha, but then I looked again at the 1993 catalog and realized the SBB had an OD of 2.56" and not 2.80" (as I'd always thought.) Therefore, my PNC80B nose cone isn't the right size--unless I upscale the SBB even more.

My question is: what nose cone DID the Super Big Bertha use?

Thanks.

It's the right size. BT-80 is 2.56" I.D. They just stuck the I.D. in the specs instead of the O.D., which is 2.6".
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Old 07-23-2016, 10:08 PM
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Ah so! Thanks.
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Old 07-24-2016, 03:06 PM
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Since the Super BB is less than twice the size of the standard BB should the fins be made from 3/16" or 1/4" stock? I have premium Midwest sheets of both, but I don't know which to use.
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Old 07-24-2016, 04:01 PM
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It depends on what you want to do with it. Some folks think a model has to fly 100,000 ft (GH), while others may just want to look at it on their shelf.

I've done several BT-80 upscales that I use at school demos. I purposely went with 1/4" balsa to keep the rocket light, but add a bit of drag. It lets me go with smaller motors and keep the rockets on small playgrounds. Believe it or not, I have a BT-80 based Red Max with 1/4" fins and a big honkin balsa nosecone that will fly on a C11-3 and could use another second of delay.

If you want to go altitude, use 1/8" ply. If you want a scale hangar queen, use 1/4" and hit it a few extra times with the sander. If you plan to fly it a lot but still want scale thickness, you can even do 1/8" ply frame sandwiched between two sheets of 1/16" balsa. It's not really that much more effort. Go TTW regardless because that's a lot leverage on a surface mount.
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Old 07-24-2016, 08:15 PM
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Will do! Thanks for the advice.

Jeff
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  #7  
Old 07-25-2016, 06:37 AM
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Or paper the balsa fins. Not positive, but I think the kit had 3/16" balsa fins. Pretty sure that is what I used on my Maxi Alpha with computer labels on the outside for strength. I'd honestly be less worried about cracking a 3/16" papered fin on landing than flutter and shred.
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Old 07-25-2016, 01:28 PM
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I would NEVER use 1/4" thick fins of ANY wood on a rocket this SMALL.
Most likely I would use epoxy mounted/filleted 3/16" Basswood or possibly 1/8" Aircraft-ply, either of which would hold up fine through H-power if it is not Warp-9 or V-max propellant.
Basswood is much easier to shape/finish than ply.
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Old 07-25-2016, 01:32 PM
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Quote:
Originally Posted by ghrocketman
I would NEVER use 1/4" thick fins of ANY wood on a rocket this SMALL.
Most likely I would use epoxy mounted/filleted 3/16" Basswood or possibly 1/8" Aircraft-ply, either of which would hold up fine through H-power if it is not Warp-9 or V-max propellant.
Basswood is much easier to shape/finish than ply.

You will never fly a demo on a tiny field where you need the drag. Get over it GH.
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Old 07-25-2016, 07:05 PM
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I just finished a clone of the SBB and went with 3/16" balsa covered in paper with TTW mounting. I build almost everything with basswood fins but have been experimenting lately with laminates. I'm gonna give it a retro inspired paint job and fly it on E-12s.
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