Help Support RocketryForum by donating using the link above or becoming a Supporting Member.


Results 1 to 17 of 17
  1. #1
    Join Date
    2nd January 2017
    Posts
    5

    Pyro Firing Times - How long to fire e-matches?

    I'm using a Altus Telemega and saw you can set the Pyro Firing Times. Is there a recommended duration when firing e-matches with a 1S LiPo (800Mah), does the recommendation change if I add a 2S as a separate Pyro battery?


  2. #2
    Join Date
    19th January 2009
    Location
    Stafford VA
    Posts
    7,188
    I'm not sure what you are asking. Is Pyro Firing Times the duration of the firing pulse, or the amount of time between some event and the start of the pyro firing?

    I've don't have the telemega, but none of the altimeters I've had allow setting the width of the firing pulse. Most are fixed at 1 second. What they do allow is adjusting how long after a trigger event the firing pulse occurs. The most common is the delay after apogee event. If your altimeter is the back-up in a two altimeter system, you might want the firing delayed a second or two after apogee.

    Handeman

    TRA #09903 L3 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  3. #3
    Join Date
    2nd January 2017
    Posts
    5
    Yes, with TeleMegas you can set the duration of the firing pulse on the Pyro channels. You can't set them on the Main and Apogee channels as you noted.

    I'm using the Pyro channels for staging, first for separation, then ignition. Upper stage is Cesaroni Red Lightning 38mm which uses a e-match type igniter.

    1 seconds seems too long for an e-match. I'm thinking between .1 and .5 seconds, probably going to use .25.

  4. #4
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,830

    Pyro Firing Times - How long to fire e-matches?

    Quote Originally Posted by TX-Redleg View Post
    Yes, with TeleMegas you can set the duration of the firing pulse on the Pyro channels. You can't set them on the Main and Apogee channels as you noted.

    I'm using the Pyro channels for staging, first for separation, then ignition. Upper stage is Cesaroni Red Lightning 38mm which uses a e-match type igniter.

    1 seconds seems too long for an e-match. I'm thinking between .1 and .5 seconds, probably going to use .25.
    Would a 1 second pulse hurt you? Most e matches fire pretty fast. That said, I cannot see how a 1 second pulse will hurt you.

    The above said, I do not have much knowledge of the Telemega. What are the outputs rated at and what is the resistance of the e match?
    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Member of the Tripoli Motor Test Committee, and keeper of the motor file

  5. #5
    Join Date
    19th January 2009
    Location
    Coopersburg, PA
    Posts
    83
    You'll find some timing info for two different types of initiators here.

    Randy

  6. #6
    Join Date
    19th January 2009
    Location
    Stafford VA
    Posts
    7,188
    The ematches tend to open when fired and current flow will stop even if the pyro channel stays on a bit longer. I can understand why there would be no adjustment for the main and apogee channels since they would always be used with matches. With that said, maybe the adjustment of the pyro channels is so they can be used with other things beside matches. I think I would leave the channel at 1 second like the main and apogee if I was using it for matches since I can't see an advantage in shortening it.
    Just MHO
    Handeman

    TRA #09903 L3 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  7. #7
    Join Date
    18th January 2009
    Location
    Virginia - Central
    Posts
    4,169
    Quote Originally Posted by Handeman View Post
    The ematches tend to open when fired and current flow will stop even if the pyro channel stays on a bit longer.
    If I understand correctly this is one of the reasons I can't figure the "series" wiring thing vs. "parallel" when trying for redundancy....or cluster airstarts -

    If an ematch fires but fails to completely ignite, - ie. pops the pyrogen off, doesn't that break the chain?
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?”
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  8. #8
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,830

    Pyro Firing Times - How long to fire e-matches?

    Quote Originally Posted by MaxQ View Post
    If I understand correctly this is one of the reasons I can't figure the "series" wiring thing vs. "parallel" when trying for redundancy....or cluster airstarts -

    If an ematch fires but fails to completely ignite, - ie. pops the pyrogen off, doesn't that break the chain?
    The firing time is so fast that it does not matter. If you are using Lipo’s, which can source a lot of current, and you do not want to the have your resistance too low- you could over current the output transistors and fry them. The devil is in the details- ohms law is a useful tool. You need to look at this from source to match. What can the battery source? What can the output circuits take, and are they current limited? What is the resistance of the load/ematch?
    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Member of the Tripoli Motor Test Committee, and keeper of the motor file

  9. #9
    Join Date
    18th January 2009
    Location
    Virginia - Central
    Posts
    4,169
    Quote Originally Posted by markkoelsch View Post
    The firing time is so fast that it does not matter. If you are using Lipo’s, which can source a lot of current, and you do not want to the have your resistance too low- you could over current the output transistors and fry them. The devil is in the details- ohms law is a useful tool. You need to look at this from source to match. What can the battery source? What can the output circuits take, and are they current limited? What is the resistance of the load/ematch?
    Thanks, - I read the big redundancy thread awhile back (IIRC discussion may have mentioned that) and I still wasn't getting it.
    Makes sense, I guess.
    Last edited by MaxQ; 7th May 2018 at 01:47 AM.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?”
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  10. #10
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,830
    Quote Originally Posted by MaxQ View Post
    Thanks, - I read the big redundancy thread awhile back (IIRC discussion may have mentioned that) and I still wasn't getting it.
    Makes sense, I guess.
    What part are you not sure of?
    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Member of the Tripoli Motor Test Committee, and keeper of the motor file

  11. #11
    Join Date
    23rd July 2011
    Location
    Butte, MT
    Posts
    2,727
    Quote Originally Posted by MaxQ View Post
    If I understand correctly this is one of the reasons I can't figure the "series" wiring thing vs. "parallel" when trying for redundancy....or cluster airstarts -

    If an ematch fires but fails to completely ignite, - ie. pops the pyrogen off, doesn't that break the chain?
    Only if the bridge wire burns through causing an open circuit. The only times I’ve seen (or had) ematches fail without lighting they still had continuity.
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  12. #12
    Join Date
    23rd January 2009
    Location
    NE Ohio
    Posts
    2,545
    Quote Originally Posted by MaxQ View Post
    If I understand correctly this is one of the reasons I can't figure the "series" wiring thing vs. "parallel" when trying for redundancy....or cluster airstarts -

    If an ematch fires but fails to completely ignite, - ie. pops the pyrogen off, doesn't that break the chain?
    When the current flows the bridgewire temperature starts to rise, quickly. If the ematches are in series the wire in each match heats at the same rate (nominally). The temperature that the pyrogen ignites is well below the temperature that the wire melts. So both wires will be well above the pyrogen ignition temperature before one of them melts and opens.
    John Derimiggio NAR/TRA L3
    MarsaSystems

  13. #13
    Join Date
    18th January 2009
    Location
    Virginia - Central
    Posts
    4,169
    Quote Originally Posted by markkoelsch View Post
    What part are you not sure of?
    Electronics in general ....not my best skill set.
    Rolling CF and Fiberglass, scaling and design and build, I'm ok.
    Most of this stuff beyond Ohms law and I'm lost.

    You guys have explained it well though.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?”
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  14. #14
    Join Date
    22nd January 2009
    Location
    Palo Alto, CA
    Posts
    2,091
    Quote Originally Posted by Steve Shannon View Post
    Only if the bridge wire burns through causing an open circuit. The only times I’ve seen (or had) ematches fail without lighting they still had continuity.
    Also, ignitors used for airstarts can have a long time at high current because the gas inside the motor is highly conductive. If you use head-end ignition you can count on having a hard short for as long as the output is active.
    Adrian Adamson
    Featherweight Altimeters LLC
    www.featherweightaltimeters.com

  15. #15
    Join Date
    19th January 2009
    Location
    Stafford VA
    Posts
    7,188
    Quote Originally Posted by Steve Shannon View Post
    Only if the bridge wire burns through causing an open circuit. The only times I’ve seen (or had) ematches fail without lighting they still had continuity.
    I had several ematches that tested about 0.7 ohm and failed to fire and where open afterwards. I fact, I had two on the same flight, both different brand commercial ematches. Fortunately the rocket fell flat from 4400 ft and was recovered without damage. Should have bought a lottery ticket that day!
    Handeman

    TRA #09903 L3 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  16. #16
    Join Date
    23rd July 2011
    Location
    Butte, MT
    Posts
    2,727
    Quote Originally Posted by Handeman View Post
    I had several ematches that tested about 0.7 ohm and failed to fire and where open afterwards. I fact, I had two on the same flight, both different brand commercial ematches. Fortunately the rocket fell flat from 4400 ft and was recovered without damage. Should have bought a lottery ticket that day!
    Wow!
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  17. #17
    Join Date
    2nd January 2017
    Posts
    5
    I had a successful flight last weekend using .25 sec for the pyro times for the separation charge and sustainer igniter (e-match). The battery was a 1S 800 mah. I also learned that it took 1.2seconds to achieve pressure after the igniter fired for the CTI H120-RL in the sustainer.


Similar Threads

  1. Help... Altus TeleMega - Why didn't Pyro-B 2nd stage igniter fire???
    By TX-Redleg in forum Rocketry Electronics and Software
    Replies: 5
    Last Post: 21st March 2018, 02:34 AM
  2. First Fire Mini/JR Firing Current
    By Firefox in forum Propulsion
    Replies: 2
    Last Post: 17th June 2016, 10:29 PM
  3. Davey Fire Electric Matches or replacements?
    By majordude in forum High Power Rocketry (HPR)
    Replies: 3
    Last Post: 16th June 2014, 03:50 AM
  4. Firing Issues - Veri-Fire Solo
    By AJM in forum Ground Support
    Replies: 16
    Last Post: 29th August 2012, 06:23 PM
  5. Replies: 26
    Last Post: 4th July 2007, 03:04 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •