Parachute mech

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
poriet
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Parachute mech

Post by poriet »

Hi,
I have just constructed a nose-cone release mechanism. It's winter and the weather is awful, so it's still not flown.
The release mechanism may not be original. I salvaged the carriage slide mechanism from a DVD. Well, actually, this one came from a CD device made by Sony, but it was only half the size of a CD or DVD ROM pc drive.( The mech from a DVD of a laptop would probably do the same job. ) The key to this one is that the motor is a simple DC motor with tiny gears, whereas quite a lot are a tiny stepper which cant be adapted to this purpose as easily. If I can work out how to do it I'll send a pic for any interested parties.
The nosecone is hinged one side and held by a small rod the other side: the rod is glued to the slider of the DVD.
The key, it seemed to me, would be to yank the slide back with sufficient force to reliably release the nose-cone which is held tight by a rubber band. The cone flips open and, with luck, the chute falls out. If it gets stuck, or doesnt deploy properly, a lot of work is going down the pan.
Another problem hs salways seemed to me to be the power source. For the first try, I used a 4-pack of AAA NiCads. I hate NiCads with a passion; unreliable. This time I've used a Li-Ion battery from a mobile phone. Although the phone was junk and the battery old, a check showed its energy was almost unimpaired. These tiny cells are very handy: plenty of power and light. By using a tiny SMPS to get 10V, I charged a 2000uF cap. This is then discharged through the motor which jerks back most pleasingly.( I've added some other refinements to shut the motor down so it doesnt keep going and damage the tiny plastic gear-wheels. )
Anyway, it seems to work like a charm on the bench. Now I have all the fun of trying to cram all this package of electroinics inside the rocket body. Time to get to grips with smd, methinks.
Regards
Bruce
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Spartan117
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Re: Parachute mech

Post by Spartan117 »

poriet wrote:Hi,
I have just constructed a nose-cone release mechanism. It's winter and the weather is awful, so it's still not flown.
The release mechanism may not be original. I salvaged the carriage slide mechanism from a DVD. Well, actually, this one came from a CD device made by Sony, but it was only half the size of a CD or DVD ROM pc drive.( The mech from a DVD of a laptop would probably do the same job. ) The key to this one is that the motor is a simple DC motor with tiny gears, whereas quite a lot are a tiny stepper which cant be adapted to this purpose as easily. If I can work out how to do it I'll send a pic for any interested parties.
The nosecone is hinged one side and held by a small rod the other side: the rod is glued to the slider of the DVD.
The key, it seemed to me, would be to yank the slide back with sufficient force to reliably release the nose-cone which is held tight by a rubber band. The cone flips open and, with luck, the chute falls out. If it gets stuck, or doesnt deploy properly, a lot of work is going down the pan.
Another problem hs salways seemed to me to be the power source. For the first try, I used a 4-pack of AAA NiCads. I hate NiCads with a passion; unreliable. This time I've used a Li-Ion battery from a mobile phone. Although the phone was junk and the battery old, a check showed its energy was almost unimpaired. These tiny cells are very handy: plenty of power and light. By using a tiny SMPS to get 10V, I charged a 2000uF cap. This is then discharged through the motor which jerks back most pleasingly.( I've added some other refinements to shut the motor down so it doesnt keep going and damage the tiny plastic gear-wheels. )
Anyway, it seems to work like a charm on the bench. Now I have all the fun of trying to cram all this package of electroinics inside the rocket body. Time to get to grips with smd, methinks.
Regards
Bruce

Can you upload pix of the system? It sounds like something that anyone could make for free, since everyone can easily strip a junk computer and cel phone. Who doesn't have 3 or 4 of each laying around the basement? LOL.
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Re: Parachute mech

Post by WRA2 »

poriet wrote:Hi,
I have just constructed a nose-cone release mechanism. It's winter and the weather is awful, so it's still not flown.
The release mechanism may not be original. I salvaged the carriage slide mechanism from a DVD. Well, actually, this one came from a CD device made by Sony, but it was only half the size of a CD or DVD ROM pc drive.( The mech from a DVD of a laptop would probably do the same job. ) The key to this one is that the motor is a simple DC motor with tiny gears, whereas quite a lot are a tiny stepper which cant be adapted to this purpose as easily. If I can work out how to do it I'll send a pic for any interested parties.
Hi Bruce,

At the bottom of the "posting page" you will find a tab called "upload attachment". Just click it and then browse to the photo on your PC using the "browse" button, then click "add the file". You can even add comments to go with the attachment (optional).

Nice work developing a deployment system using the remains of a CD/DVD drive. PH:
Lisa Walker,
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poriet
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Re: Parachute mech

Post by poriet »

Thanks for the info, Lisa.
I appreciate your comments, but whether or not it's a nice development remains to be seen!

Bruce
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U.S. Water Rockets1
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Re: Parachute mech

Post by U.S. Water Rockets1 »

poriet wrote:Thanks for the info, Lisa.
I appreciate your comments, but whether or not it's a nice development remains to be seen!

Bruce
Have you stripped the mechanism down to just the motor and gear system, or are you actually flying the CD tray and frame and all that junk? You could easily cut most of the excess stuff off the CD drive and just use the part of the mechanism that works like a powerful linear servo. A really cheap and easy linear servo motor would be useful in more than just deploy systems. That's a good suggestion!
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Re: Parachute mech

Post by WRA2 »

poriet wrote:Thanks for the info, Lisa.
I appreciate your comments, but whether or not it's a nice development remains to be seen!

Bruce
You are welcome.
It's winter here on the forum too! :D
Lisa Walker,
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bugwubber
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Re: Parachute mech

Post by bugwubber »

Facinating, I have a junk phone and a dvd player that is just barely playing dvds. I've been thinking its time for new dvd player... :-)
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