Nine Motor Cluster. My 2015 Project

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SteveA

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Flew on seven, thought I might try nine.


Sigma-3.jpgSigma-2.jpgSigma.jpg

Have a good one!
Steve
 
Is it stable fully loaded?

Ditto!
Even with 8 fins those tiny fins are WAY to small to provide stablitiy to this design. I just recently built a 7motor model of the Conestoga 1620 rocket. I had fins about the same porportion and the model was compeltely unstable right off the launch rod. After re-sizing the fins the model is completly stable in all motor configurations.

Add about 10% fin area to your design then check the stability again.
 
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Yeah, too small on the fins but it looks KILLER! I would envision the same fin scheme there but have 4 of them clear material but a portion painted to look like all the other little fins. That's a good looking rocket! I like the visual proportions.
-Ken
 
First, thanks for all the great comments and yes, it is stable fully loaded. I played with the length and the nose mass until it worked out to be a stable flyer. I designed it late last summer and wanted to build it in the wake of my seven motor cluster, but rocketry season ended for me and I didn't really get a chance and then the move came and postponed it indefinitely until now. So, I'll build it this spring and hopefully fly it before the Kansas summer winds get cranked up. QQuake, you bet. I'll post the file. :eek:
 
NICE! Yeah, that's my philosophy too. The more motors, the more smoke, fire, and roar=more fun. And, more to go wrong, but what the hell...right? Plus it make for some pretty cool smoke plumes.

More motors = more fun

Here's the business end of a Falcon 9 I built.
View attachment 256505

It flies on a core 29 and 8 outboard 18's.
 
NICE! Yeah, that's my philosophy too. The more motors, the more smoke, fire, and roar=more fun. And, more to go wrong, but what the hell...right? Plus it make for some pretty cool smoke plumes.

You bet. I haven't flown it with the outboards yet, but I finally got some alligator clips to whip up a whip. Maybe this weekend?
 
Very cool. And if the winds don't cooperate in Western Kansas you can always go West to the calm Summer launch days at CRASH.

The winds never cooperate in Western Kansas. We have two speeds here, high and higher. I might just take you up on your offer.
 
John and Ken, the simulations produced stable fights each time. That being said, launches have to be on days when there are no winds or extremely light winds. Otherwise she's a bit wobbly off the rod.
 
John and Ken, the simulations produced stable fights each time. That being said, launches have to be on days when there are no winds or extremely light winds. Otherwise she's a bit wobbly off the rod.

Simulations and Free Flight are two very different environments. Particularly with Roc-Sim! I can all but guarantee if you build it and fly it with those tiny fins even if all motors ignite it will be all over the sky with the first tiny cross wind disturbance. Increase the size of your fins, which will not harm or alter the design but will make your model eligable for a second flight rather then rebuilding.
 
The winds never cooperate in Western Kansas. We have two speeds here, high and higher. I might just take you up on your offer.

Go West Young Man! The wind at Sunday's launch was so dead calm the Pad Fuhrer launched a MPR minimum diameter bird to 3,700 feet and it landed about 60 feet off the range. Short, low power distanced recovery walks for all the high power guys, they barely got any exercise. At a mile high the rocket will perform better. If that is not good enough just get in the car early in the morning and go to 8,000 feet at Hartsel in South Park. You will be top dog with your roc simmed wonder. With good science you will be well ahead of the guys in line with their ME 163, crazy train and jet pack Barbie rockets.
 
There's only one way to know for sure. Stick a sack full of motors in that puppy and let her rip! :duck:
 
Simulations and Free Flight are two very different environments. Particularly with Roc-Sim! I can all but guarantee if you build it and fly it with those tiny fins even if all motors ignite it will be all over the sky with the first tiny cross wind disturbance. Increase the size of your fins, which will not harm or alter the design but will make your model eligable for a second flight rather then rebuilding.

I'll increase the fins. I'm not too worried about igniting nine. Seven lit fine (I don't use clip whips) I figure the addition of two was not that significant.

It's lengthy, but the back half is the scouts fighting over who gets to carry it back.

[video=youtube;84MXaFYC-Go]https://www.youtube.com/watch?v=84MXaFYC-Go&spfreload=10[/video]
 
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