Jump to content


Photo
- - - - -

ejection system


  • Please log in to reply
12 replies to this topic

#1 chand

chand

    Playing with fire

  • Full Member
  • PipPip
  • 41 posts

Posted 25 March 2015 - 10:04 AM

What are types of ejection system and I need a good ejection system which eject my prachute for bigger rocket

#2 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 25 March 2015 - 10:30 AM

Here, let me get that for you...

 

http://lmgtfy.com/?q...ejection system


  • Piccaso likes this
Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#3 gregh

gregh

    Pyrotechnician

  • Full Member
  • PipPipPipPip
  • 333 posts
  • Gender:Male
  • Location:Kentucky
  • Interests:Fireworks, Family, Fireworks, Classical Guitar, Did I mention I love fireworks?

Posted 25 March 2015 - 02:38 PM

That still cracks me up, +1 Dag!



#4 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 25 March 2015 - 09:28 PM

Love to help but...

 

SPOON-FEEDING-re%20(1).gif


Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#5 chand

chand

    Playing with fire

  • Full Member
  • PipPip
  • 41 posts

Posted 11 April 2015 - 12:35 PM

guys can we build ejection system with using accelernometer it will measuer 0 g and it will apply volt to ignitor

#6 Shunt

Shunt

    Pyromaniac

  • HE Qualified
  • PipPipPip
  • 113 posts
  • Gender:Male
  • Location:Southeast USA
  • Interests:Good times with good friends I can trust with pyro.

Posted 11 April 2015 - 06:43 PM

Is this possibly a language translation issue?  If that is the problem I would like to help  :whistle:



#7 stix

stix

    Firebreather

  • Donator
  • PipPipPipPipPip
  • 1,103 posts
  • Gender:Male
  • Location:Australia
  • Interests:Pyrotechnics, Model Rocketry, Programming, Photography

Posted 11 April 2015 - 08:40 PM

guys can we build ejection system with using accelernometer it will measuer 0 g and it will apply volt to ignitor

 

I think this is very well thought out and absolutely brilliant!

 

I'm left wondering if the accelernometer will measuer (weigh) 0 grams, which would be handy indeed, OR if the accelernometer will measuer 0 g's as in gravities - which could indicate it's broken or not moving.

 

I love the ambiguity - perhaps a career in politics is beckoning?

 

Thankyou Chan :P


I just start the conversation - someone else has to question them.


#8 MrB

MrB

    Firebreather

  • HE Qualified
  • PipPipPipPipPip
  • 1,748 posts
  • Gender:Male

Posted 12 April 2015 - 10:56 AM

Accelerometer, measuring G-forces. To the best of my understanding, something set up to trigger like this would trigger pretty much as soon as the motor burns out. While you at that point have loads of stored up energy left to expend, decelerating while gaining altitude. (G-forces in the opposite direction.)

And at the peak of hight you'd hit a new 0-G state, and start accelerate back towards earth. You would then experience crazy G's shortly, and then be static at zero. I guess the static zero could trigger the parachute, but i have a feeling it's a bit late, your lawn dart would be stuck firmly in the ground at this point...

 

You could use a G-force sensor to trigger a parachute, but i have a feeling it's a bit more complicated then you really want to consider. I'd suggest using the launch g-forces to trigger the system, and then measuring the deceleration to get a baseline for when you want to trigger it. But i'm not really in to this sort of rocketry, so i wouldn't really know.

 

Isn't an altimeter a better choice? When it starts to return values that means your on the way down, trigger.

B!



#9 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 14 April 2015 - 08:12 PM

Its a LOT more complicated but you have the nuts and bolts of it B.  It's super easy to zipper an aluminum tube with Kevlar shock cord if it doesn't get cut!  I had a 3 meter J powered rocket zipper at 2000' ASL that broke the 10,000 pound shock cord off the canopy shroud leaving the broken canopy to float back down by itself and allowing 120# of aluminum to lawn dart into about 6 feet of hard farmers field.  We never did get the nose out of the dirt, it was deeper down than the shovel would reach...  

 

$3000 lawn dart, that one.  


  • stix likes this
Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#10 MrB

MrB

    Firebreather

  • HE Qualified
  • PipPipPipPipPip
  • 1,748 posts
  • Gender:Male

Posted 15 April 2015 - 03:10 AM

Its a LOT more complicated but you have the nuts and bolts of it B.

 

Yeah, it's simplified, but to me it makes a lot more sense with a flight-recorder and a altimeter, then g-force. A G-force sensor might provide "interesting" data, If you can recover the data from the lawn dart.

 

It's super easy to zipper an aluminum tube with Kevlar shock cord if it doesn't get cut!  I had a 3 meter J powered rocket zipper at 2000' ASL that broke the 10,000 pound shock cord off the canopy shroud leaving the broken canopy to float back down by itself and allowing 120# of aluminum to lawn dart into about 6 feet of hard farmers field.  We never did get the nose out of the dirt, it was deeper down than the shovel would reach... 

 

Damn. I mean, yeah, the forces on the parachute & cords when it catches the air will be intense. Thanks for sharing.

B!



#11 stix

stix

    Firebreather

  • Donator
  • PipPipPipPipPip
  • 1,103 posts
  • Gender:Male
  • Location:Australia
  • Interests:Pyrotechnics, Model Rocketry, Programming, Photography

Posted 15 April 2015 - 03:23 AM

Sh*t Dags - that's one expensive lawn dart :o

 

My last attempt at parachute recovery (about 3yrs ago) was a failure - but a bit less expensive. It was more about the time lost. Disappointing though because I spent a lot of time making an electronic delay unit. The unit was made as small as possible on vero board to fit into the smallest body tube possible that suited my standard "E" sugar motors (KNDX).

 

I did a lot of testing before hand. The ejection charge was fired using the mini light bulb method. The timer was activated as the rocket left the launch tower via a small reed switch and magnet. Tested and tested again. I'll never really know what happened, but the rocket took off like the "powers of piss" and soon disappeared - It was only about 2ft high and as you would know, it gets hard to visually track after a couple of hundred meters.

 

The theory using the delay (timed ejection) was that I used OpenRocket to determine how long after launch it would reach apogee. I was confident in the reliability and total impulse of my motors, so this seemed like a reasonable solution for determining the time of parachute ejection. I added a couple of seconds to be sure it had apexed and was heading down.

 

Who knows. Perhaps the ejection system worked exactly as planned but the rocket was heading back down with great speed and ripped the recovery system to shreds.

 

An electronic altimeter or accelerometer or the other one that uses the earths magnetic field to determine apogee seems like a good solution but expensive. I did some research a few days back about "mechanical systems" which I've always been fond of and saw a contraption that Dan Pollino came up with (he is well regarded in the amateur rocket world). I thought I'd bookmarked it but can't find it now.

 

It was very similar to a crackpot solution that I had in mind some years back. In essence, a ball bearing was contained in a structure that would fall or make an electrical contact ONLY when apogee was reached, and therefore cause ignition of the ejection charge. I really like those mechanical device ideas (I guess I'm showing my age).

 

At the moment I'm getting back into rockets (sidetracked again!!) Got some cheap Sorbitol so I'm experimenting. Actual recovery of the rocket is the main game AFAIC, so I'm going to post in this thread my thoughts and ideas for a simple, reliable mechanical ejection system.

 

Anyways, this thread could do with some more nonsense :D

 

Cheers.


Edited by stix, 15 April 2015 - 03:30 AM.

I just start the conversation - someone else has to question them.


#12 dagabu

dagabu

    Grandmaster

  • Donator
  • PipPipPipPipPipPipPipPipPipPip
  • 8,784 posts
  • Gender:Male
  • Location:Up Nort

Posted 17 April 2015 - 04:43 PM

That's pretty normal for a dart with that kind of telemetry gear in the nose, all sorts of engineering went into that one and we still got the programming wrong. 


Dave
 
PGI Member http://www.pgi.org
IPA Member http://www.iowapyro.com
 
"The art of fire is indeed the supreme art; for fire is at once the universal slave, the universal master."

#13 WRAITH

WRAITH

    Playing with fire

  • Full Member
  • PipPip
  • 30 posts
  • Gender:Male
  • Location:South Australia
  • Interests:Chemistry, Pyrotechnics, Mini Scale Modern Cannons Jet Turbines (thermodynamics), Model Rocketry, Electrotechnology, Mechanical Engineering & Philosophy.

Posted 24 February 2021 - 06:41 PM

Old post, but maybe someone could gain from this idea for firing the ejection charge without the use of computer aided devices. Just simple electronics use of a 12V A23 battery, then making a nichrome bridge tilt switch circuit. Simple circuit & fires when needed by the use of a reed switch or directional tilt switch, either made with mercury encapsulated in glass or metal powder in glass. Switch is placed upside down in rocket & during apogee or when it starts levelling out the encapsulated material makes the circuit complete, heats nichrome & ejection charge fires the parachute at zero G's.
  • WRAITH likes this




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users