Reliable timer release

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
SaskAlex
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Reliable timer release

Post by SaskAlex »

Well last year I made the first version of my current parachute deployment system. There are virtually no external parts, it's light (just 48 grams without parachute), and it hasn't failed me yet. I thought it was rather unique until I saw Air Command's video of their system, which is fairly similar.

I'm not much for computer animations, so I just took a bunch of pictures.
Attachments
The nose cone is permanently attached to the base of the system with braided fishing line. It has open cell foam inside to act as a spring. The parachute is attached to a loop of string on the base with a simple lark's head knot.
The nose cone is permanently attached to the base of the system with braided fishing line. It has open cell foam inside to act as a spring. The parachute is attached to a loop of string on the base with a simple lark's head knot.
DSCI0050.JPG (88.76 KiB) Viewed 195 times
A piece of PET is used to jam the gears of the timer. It runs through a hole in the wall and gets pulled out at launch.
A piece of PET is used to jam the gears of the timer. It runs through a hole in the wall and gets pulled out at launch.
DSCI0042(2).jpg (39.84 KiB) Viewed 195 times
The plate is made out of plywood about 1/4" thick. It is turned on a lathe to be a precise fit, but careful sanding would probably be fine, too. It is gooped in place, and a little more than 1/16" sticks above the PET. The nose cone fits on very precisely and comes off easily.
The plate is made out of plywood about 1/4" thick. It is turned on a lathe to be a precise fit, but careful sanding would probably be fine, too. It is gooped in place, and a little more than 1/16" sticks above the PET. The nose cone fits on very precisely and comes off easily.
DSCI0049.JPG (32.16 KiB) Viewed 195 times
DSCI0038(2).jpg
DSCI0038(2).jpg (31.87 KiB) Viewed 195 times
A piece of wire with a hooked end is used to pull the elastics through a hole in the plywood and onto the timer.
A piece of wire with a hooked end is used to pull the elastics through a hole in the plywood and onto the timer.
DSCI0040(2).jpg (32.06 KiB) Viewed 195 times
DSCI0041(2).jpg
DSCI0041(2).jpg (31.71 KiB) Viewed 195 times
My payload is an MD-80 clone and a perfectflight alt15k on a frame made of popsicle sticks. The altimeter and camera are easily removable.
My payload is an MD-80 clone and a perfectflight alt15k on a frame made of popsicle sticks. The altimeter and camera are easily removable.
DSCI0045.JPG (87.58 KiB) Viewed 195 times
DSCI0046.JPG
DSCI0046.JPG (87.53 KiB) Viewed 195 times
The payload friction-fits into the payload bay
The payload friction-fits into the payload bay
DSCI0044(2).jpg (35.99 KiB) Viewed 195 times
It friction-fits into a sleeve attached to the rocket
It friction-fits into a sleeve attached to the rocket
DSCI0047.JPG (92.65 KiB) Viewed 195 times
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wracing
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Re: Reliable timer release

Post by wracing »

Very Nice! Thanks for sharing.

Best - W
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U.S. Water Rockets
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Re: Reliable timer release

Post by U.S. Water Rockets »

Would this be the same system you use on your recent 1000+ foot launches?

That's really impressive that you have managed to break 1000 feet without resorting to all of the fancy technology that people have been trying to use for years and have failed. You better be careful because you're going to make everyone jealous! LOL!

Great work!
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SaskAlex
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Re: Reliable timer release

Post by SaskAlex »

U.S. Water Rockets wrote:Would this be the same system you use on your recent 1000+ foot launches?

That's really impressive that you have managed to break 1000 feet without resorting to all of the fancy technology that people have been trying to use for years and have failed. You better be careful because you're going to make everyone jealous! LOL!

Great work!
Yes, this is the system I have been using on all my recent launches. I think the key to a reliable mechanical release is simplicity. And I don't think you can make any electronic system lighter than a simple mechanical one like mine. I think the advantages of fancy technology are that it can be easier to make it dependable, and they can have greater ease of use. I just finished my second year of electronic systems engineering, so I'm sure I'll be trying out some more high tech methods in the not-too-distant future. For now, though, I'm really happy with this system.
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Tim Chen
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Re: Reliable timer release

Post by Tim Chen »

Alex,

Do you have a timer on the boosters as well as one on the sustainer?
Tim Chen
Captain, Team Enterprise
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SaskAlex
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Re: Reliable timer release

Post by SaskAlex »

Tim Chen wrote:Alex,

Do you have a timer on the boosters as well as one on the sustainer?
Yes, the booster has it's own timer. The parachute just sits on top of one of the bottles making up the booster, and long elastic runs over top of it and to a timer on the side of the bottle. I don't care about the aerodynamics of the booster since it travels such a short distance, so it's a really simple set up.
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