Failed Parachute Deploy & Ballistic Trajectory

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david2665
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Failed Parachute Deploy & Ballistic Trajectory

Post by david2665 »

Hi all,

So i finally got round to launching a rocket, to test the Launchpad AlTImeter and axial deploy system.

I aready posted the launch video http://www.wra2.org/forum/viewtopic.php?f=53&t=2932

The parachute failed to deploy, which is strange because the Launchpad AlTImeter (US Water Rockets TH: !!!) logged an apogee of 101ft. I assume the servo moved, since the rubber band had released, and it never failed to move during ground tests.

Can't be sure what caused the nosecone not to come off.....since its now a further 1 inch compressed onto the body !!!

I'm thinking:

1. Spring is too weak to overcome the force of the airflow?? Maybe due to the trajectory?
2. Vaccuum inside the nosecone held it onto the body??


Also, there was absolutely no wind, yet the rocket took off and immediately assumed a ballistic trajectory.

I'm interested to know peoples thoughts on this one.

Maybe its because i didn't use a launch rail to guide the rocket in the initial stages? Can a slight misalignment (fins, body sections) cause a rocket to fly in this way?


Dave
Astrofox
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Re: Failed Parachute Deploy & Ballistic Trajectory

Post by Astrofox »

Dear Dave,
I noted that just before launch, the bottle rocket was not entirely upright and was tilted slightly. Because of that, the bottle rocket assumed a ballistic trajectory. This is a form of a g-turn, which is a commonplace in real rocket launches, and such phenomena is caused by pitching the craft down slightly and letting the aerodynamics of the craft take over.

I am not sure as to what may have stopped the deployment of the chute, but I have had cases that involve the parachute attaching itself to any stray pieces of tape, or snagged onto a piece of plastic. But of course, this may not be the case with your rocket.

Good luck with launches!
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Blenderite
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Re: Failed Parachute Deploy & Ballistic Trajectory

Post by Blenderite »

I am going to have to agree with Astrofox. I think the trajectory was caused by initial angle.

As far as the parachute failure, how was your deployment system designed? Was the setup built like USWR shows in their tutorial? Let us know more about the design and perhaps we can help. Pictures are worth a thousand words!!
-Blenderite

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