CP/CG for Centuri USS America

I'm trying to build a clone of the Centuri USS America, does anyone
have either a good CP or a model that they can load with a C6-3 and
measure the CG?
I know the original didn't require nose weight, but I plan on a 24mm
mount and basswood fins extending thru the booster tubes into the
motor mount, so I can use RMS reloads and less fin breakage.
Couldn't find it in RMRR or google.
Thanks,
Bob Ellis
Reply to
Bob n Robin
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Those things were very stable. Add power without guilt.
Reply to
Jerry Irvine
Thanks Jerry, but I was also considering upscalling it and wanted to see just where the CP/CG was to decide if it could handle plywood/G10/glassed fins for a future model.
I remember the fins as being really easy to break, even with the trussed shock cord. If it has a really good stability margin I should be able to build the fins a bit heavier. If it isn't that good a margin, I might have to extend the central BT a bit and add some weight to the nose to get the margin back.
Bob Ellis
Reply to
Bob n Robin
Do the cardboard cutout method for the CP. Then when you build itadjust the CG with mass.
IIRC it also has draggy elements near the fins this increasing DYNAMIC stability.
Jerry
Reply to
Jerry Irvine
Jerry,
Look at the model on JimZ, it's three non-symetrical body tubes, six fins of three different sizes and shapes, all attached to the outboard tubes not the central BT. Add in six engine pod (tubes) and that's a few too many cardboard cut-outs for me.
Still looking for someone with an old model that can fit a motor and tell me where the real life CG is.
Bob Ellis
Reply to
Bob n Robin
I have the yellow one in stock. But My "America" was crushed by multiple C5-3 flights well over a decade ago.
Jerry
Reply to
Jerry Irvine
I have the kit assembled, haven't flown it, never will as it's a beautiful kit.
Don't have any C6-3's, just a C6-5, which should be close by a couple of grams or so. The CG on a stock U.S.S. America with said C6-5 is 8.25 " from the very end of the center body tube. That is also without chute, everything else in the kit is installed including baffle port system and butterfly shock cord attachment.
Just in case you get another upscale urge the E.S.S. Raven is 10 inches from the motor end (I might try that although a stock atmospheric scoop would have some kind of drag.
Paul
Reply to
buffalo
Thank you Paul!.
The difference between a C6-3 and C6-5 is only about .1 gram, not a problem. But, could you measure again with a bit of wadding and a chute (even one not assembled, just plastic and string). On that design rocket the chute sitting ahead of the baffle can move the CG forward quite a bit. (Keep saying to yourself "I must resist the urge to fly this...I did my L1 Cert on an NCR Intercepter G with out a scratch, then zippered it on the next flight.)
BTW, I assume that the 8.25" is from the rear of the center body tube?
Thanks for the info on the Raven, it's on my list, along with the Greyhawk.
Bob Ellis
Reply to
Bob n Robin

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