ZX-21...time to cluster...

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All motors ignited and the ejection charge left no residue or marks on the chute. Baffle worked well. We loaded 'er up one more time and everything went as planned with the exception of a slight weathercock due to a sudden gust. I'll be building more cluster birds. :D
 
Originally posted by Martin Vrstal
...
Come on down and fly it with me at MWP2
https://tripoliquadcities39.com/page11.html
Would really enjoy that Marty. That launch is well within the window of driving from where I live too. Unfortunately, I have a trip on that week/weekend which was planned a few months back. Make sure ya get some good pics so I can see what I missed. ;)
 
Here's another showing the boost. She left quite a smoke trail.
 
Originally posted by daveyfire
Beautiful project, Stones! Looks like a fantastic cluster bird... is there an upscale in the works? :)
Hmmmmm.....wonder what I could come up with for a NC for 3"/4" version? I'm thinking pink foam again. ;)
 
Stones,

Excellent design; Great flights!

Apparently, your rocket design shows the RockSim equations as being better at predicting stability than the Barrowman equations. That says a lot for the mathmatics behind the program, I wonder how other software packages compair since most use the Barrowman equations. This is a great example to validate the flight stability predicted by RockSim simulation program.

Bruce S. Levison, NAR #69055
 
great job Stones - thanks for the pictures!

cool rocket!
 
Originally posted by teflonrocketry1
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This is a great example to validate the flight stability predicted by RockSim simulation program.

Bruce S. Levison, NAR #69055
At least, for the 2 flights it has on it so far. ;)
As much as we all trust the Barrowman equations, I wanted to prove to myself, if nothing else, that if the Rocksim equation says it's stable, then I'll trust it to be stable. Otherwise, why have a Rocksim equation at all.
Granted, this was a fairly low wind couple of flights, no more than 6-7 mph but, that 1st flight was almost unbelievably straight. I'll post future flights to see if it was a fluke.
 
nice job,I also go by the rocksim results...I don't even turn on the barrowman... I've never had one go unstable.... after seeing your great pic . it's time to build annother D-cluster!
 
Originally posted by Elapid
beautiful pics!

as far as trusting rocksim's stability calculations without question, i'd ask Jamie Clay about that one.
:(
details can be found here:
https://www.dph.com/vidroc/Joe/index.htm

I believe that there is a major problem with the way Jamie Clay is interpreting the RockSim file he is using; no wonder he doesn't trust the software! I get a Static Margin on an M motor for Barrowman of 1.02, and 1.67 by RockSim, not enough for stability on a long rocket with small fins!

Bruce S. Levison, NAR #69055
 
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