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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

Mechanical (not magnetic) Apogee Detector

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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Alien Space Agency
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Mechanical (not magnetic) Apogee Detector

Post by Alien Space Agency » Wed Feb 10, 2016 9:31 am

Hi guys :)

Can anyone share their thoughts about this recovery system?
http://www.youtube.com/watch?v=ldaHifNAxsg

How effective do you think this is?


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Re: Mechanical (not magnetic) Apogee Detector

Post by skysaber89 » Wed Feb 10, 2016 10:55 am

This looks to be quite fascinating. I would love to see this tested. Mechanical apogee detectors are inherently less reliable, at least I would think this to be the case, because of the moving parts. This one seems very well thought out however. It very well could work nicely.
It does seem that it is adding a lot of unnecessary weight, though. It also cannot be used in WRA2 competitions as it is made from metal bits. That is my understanding of the rules, though I could be wrong.



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Re: Mechanical (not magnetic) Apogee Detector

Post by Alien Space Agency » Wed Feb 10, 2016 11:07 am

Yeah, I do think so as well. But if used for research, it would be perfect, especially if you don't know when to deploy the chute.


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Re: Mechanical (not magnetic) Apogee Detector

Post by addstogether » Wed Feb 10, 2016 9:00 pm

It should be fine in WRA competitions I think if it was in its own plastic deployment bay separate from the pressurised components and therefore no metal parts in contact with pressurised rocket. Well that's my thought on it. I could be wrong however a quick email to find out might be in order.



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Re: Mechanical (not magnetic) Apogee Detector

Post by addstogether » Wed Feb 10, 2016 9:06 pm

Have you thought of using threaded plastic rods instead of metal. These can be picked up from most hardware stores.



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Re: Mechanical (not magnetic) Apogee Detector

Post by Alien Space Agency » Thu Feb 11, 2016 12:09 am

The metal rods act as the contacts for activating the mech. I was thinking of arranging the contacts like a cage so no matter what orientation the rocket is in, as long as it tips past 100 deg, it will deploy. Here is a rough MSP drawing of my idea:
mad.png
The red circles are the positive terminals, and the blue, negative. The black circle is the ball bearing.

Kudos.

Maru
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Re: Mechanical (not magnetic) Apogee Detector

Post by motorcyclepilot » Thu Feb 11, 2016 2:32 pm

I think US Water Rockets Air Command Rockets discounted all mechanical apogee detectors as unreliable. Since the rocket and the mechanism are in the same inertial frame, you cannot rely on gravity to trigger this device.



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Re: Mechanical (not magnetic) Apogee Detector

Post by Alien Space Agency » Fri Feb 12, 2016 12:13 am

The metal ball bearing is free to move around the mechanism. After burnout, the bearing moves up, once it tips over, it moves to one side and activates the servo.


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Re: Mechanical (not magnetic) Apogee Detector

Post by motorcyclepilot » Fri Feb 12, 2016 4:09 pm

Alien Space Agency wrote:The metal ball bearing is free to move around the mechanism. After burnout, the bearing moves up, once it tips over, it moves to one side and activates the servo.
Yes, the bearing is free but why would it move "up" or to one side? Taking acceleration into consideration, the bearing would move up immediately after burnout when the rocket is no longer accelerating, not at apogee, causing an early chute deployment.

I was wrong about credit for testing of gravity mechanisms. It was Air Command Rockets. Sorry guys!

Here's a link to their test video: https://youtu.be/oC8AbWXFiTw

Worth watching, as they have in-flight video of testing a gravity based mechanism.

If gravity based mechanisms were reliable then we would all be using them for apogee detection and deployment due to their simplicity and ease of construction.



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Re: Mechanical (not magnetic) Apogee Detector

Post by Alien Space Agency » Fri Feb 12, 2016 9:07 pm

Well that problem is already taken into account when Dan was designing this. Actually the contacts are on the side, and not on the top. So no activation comes during burnout.
BEEF].png
PS. Before I came here ACR was my guide. So I more or less watched ALL their vids.
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Re: Mechanical (not magnetic) Apogee Detector

Post by addstogether2 » Thu Apr 28, 2016 11:36 pm

Yes Air Command's site has been a goto for many!


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