View Single Post
  #27  
Old 01-14-2007, 08:52 PM
CPMcGraw's Avatar
CPMcGraw CPMcGraw is offline
BARCLONE Rocketry
 
Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
Default

Quote:
Originally Posted by John Brohm
Hey Craig - it's looking good. I'm looking forward to building this one.


I'm hoping the second prototype comes out lighter than the first one. Somehow the weight built up in the construction, and killed any chance it had of flying correctly. It took a full quarter ounce of lead to bring the CG/CP margin into the safe zone, on top of that.

If the second prototype balances where RockSim says it should (and I have my doubts even now), the flight performance should be quite good on a "B". I think RockSim is calculating the weight of the nose cone heavier than Carl's BC-760 actually is, and it's throwing the margin out of whack. I need a digital scale that can resolve finer points than a typical postal scale.

ADDENDUM: THAT'S ONE PROBLEM! RockSim is recording the weight of the nose cone as being 0.2258 oz, while the SEMROC website is saying the nose cone only weighs 0.09 oz. That's roughly 2.5X what it should weigh. What this means is, RockSim is over-estimating the typical weight of bulk balsa. I will go into the file and re-compute the design based on the website weight, and report on the results shortly.
__________________
Craig McGraw

BARCLONE Rocketry -- http://barclone.rocketshoppe.com
BARCLONE Blogsite -- http://barclone.wordpress.com
BARCLONE Forum -- BARCLONE Forum

BARs helping BARs

SAM 0044
AMA 352635
Reply With Quote