Modified CTI igniter in Aerotech motor

Discussion in 'Propulsion' started by billdz, Jan 11, 2019.

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  1. Jan 11, 2019 #1

    billdz

    billdz

    billdz

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    My understanding is that CTI igniters are basically ematches that ignite a pyrogen pellet in the top grain. AT igniters, in contrast, have their own pyrogen. Thus, since there is no pyrogen pellet in AT motors, CTI igniters do not work in AT motors.

    At a recent launch, I saw a guy using modified ematch/CTI igniters with AT motors. He said he either wrapped a piece of cannon fuse around the tip of the ematch or dipped the tip into glue and rolled it in black powder. Worked fine for him, but I'm thinking these methods can be unsafe unless you really know what you are doing.

    Anyone tried this?
     
  2. Jan 11, 2019 #2

    ECayemberg

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    Yes.

    People have been augmenting e-matches for decades. However, not all ematches play nice with pyrogen varieties. One needs an e-match that burns slowly enough to reliably ignite the pyrogen which then ignites the propellant. Many low current matches burn too fast to reliably ignite the augmented pyrogen. Typically, the higher current, longer burning matches are the appropriate choice here.

    I'm a bit out of touch with the current match offerings; I only speak Daveyfire and Oxral ;).

    -Eric-
     
  3. Jan 11, 2019 #3

    timbucktoo

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    People at Dyer Park dip CTI matches in CA glue & then in BP. Talk to Mike or Rick.
     
  4. Jan 11, 2019 #4

    jrkennnedy2

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    I've had pretty good results with QuickDip on CTI starters.

    https://www.apogeerockets.com/Rocket_Motors/Motor_Starters/QuickDip

    It seems to be able to reliably start AT 38 and 54 single-use motors. For grins I occasionally light one off (starter, not motor) on the driveway just to watch it sparkle. Works well there too, at least real spark-ly...

    FWIW

    :)
     
  5. Jan 11, 2019 #5

    Reinhard

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    In my admittedly limited experience, AT Blue Thunder motors will light just fine with an ematch. Other propellants are likely different. Some CTI igniters also come with pyrogen (e.g. Vmax and anything 75mm+).

    Most issues with motor ignition don't result in unsafe conditions - even catos are no threat if the proper safety distances are observed. Clusters are different, but those can be challenging with most types of igniter.

    Reinhard
     
  6. Jan 11, 2019 #6

    jimzcatz

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    You can get pellets at Walmart. Work fine in ANY motor.
     
  7. Jan 12, 2019 #7

    Banzai88

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    I've asked before and no one has ever answered: Do you just drill out the top grain to fit and insert the pellet?
     
  8. Jan 12, 2019 #8

    Steve Shannon

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    No, do not drill the grain. Select a Pyrodex pellet that fits the existing core.
     
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  9. Jan 12, 2019 #9

    timbucktoo

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    50 caliber pellets fit in 75mm motors no problem. I think they make smaller caliber pellets that will fit 54mm nozzles, if not just shave them down to fit. I just feed an e-match through the pellet & insert like any other starter. Have to shave the hole a bit with exacto. Very reliable.
    IMG_4948.jpg
     
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  10. Jan 12, 2019 #10

    Steve Shannon

    Steve Shannon

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    Yes, they make them in 45 or 50 caliber and they can be trimmed to fit.
     
  11. Jan 12, 2019 #11

    mhanna

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    I've used the pellets on 38mm motors and they have worked every time.
     
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  12. Jan 12, 2019 #12

    Nytrunner

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    Can you embed the pellet in the top grain (essentially creating a cesaroni setup)?

    Or does that then make the motor "research".....
     
  13. Jan 12, 2019 #13

    Steve Shannon

    Steve Shannon

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    That’s basically what you’re doing. In my opinion it’s not a modification.
     
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  14. Jan 12, 2019 #14

    billdz

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    What is the brand name or product numbers for the Walmart pellets? Just looked at their website but did not see anything that looks like what is eing discussed.
     
  15. Jan 12, 2019 #15

    timbucktoo

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    Try a gun shop. Not all Walmart’s carry them. They’re made by Pyrodex. Cabellas or bass pro shop also carries them.
     
  16. Jan 12, 2019 #16

    billdz

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  17. Jan 12, 2019 #17

    timbucktoo

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    Yes but what's your issue with conventional starters anyway? I only use them for Loki & AT 75 mm motors on up.
     
  18. Jan 12, 2019 #18

    Steve Shannon

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  19. Jan 12, 2019 #19

    billdz

    billdz

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    No issue, just trying to learn. What about the cannon fuse?
     
  20. Jan 12, 2019 #20

    jimzcatz

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    You do not have to find them to fit through the nozzle.You build the motor with it in. If it won't fit the core, you can break it up Largest piece will usually suffice.The only time you need nozzle clearance is if you are making stick ignitors, which most of us do with big/long motors. And no, making your own ignitors does not change you to "Research" .
     
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  21. Jan 12, 2019 #21

    timbucktoo

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    What is your ignition source?
     
  22. Jan 12, 2019 #22

    billdz

    billdz

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    Ematch or CTI igniter
     
  23. Jan 12, 2019 #23

    timbucktoo

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    don't think it will light canon fuse but I have never tried it. BP pellets guaranteed to light with ematch.
     
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