Modified CTI igniter in Aerotech motor

[billdz]

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?

 

[ECayemberg]

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-

 

[tim cubbedge]

People at Dyer Park dip CTI matches in CA glue & then in BP. Talk to Mike or Rick.

 

[jrkennedy2]

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

 

[Reinhard]

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.

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+).

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.

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

 

[jimzcatz]

You can get pellets at Walmart. Work fine in ANY motor.

 

[Banzai88]

You can get pellets at Walmart. Work fine in ANY motor.

I've asked before and no one has ever answered: Do you just drill out the top grain to fit and insert the pellet?

 

[Steve Shannon]

I've asked before and no one has ever answered: Do you just drill out the top grain to fit and insert the pellet?

No, do not drill the grain. Select a Pyrodex pellet that fits the existing core.

 

[tim cubbedge]

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.

 

[Steve Shannon]

Yes, they make them in 45 or 50 caliber and they can be trimmed to fit.

 

[mhanna]

I've used the pellets on 38mm motors and they have worked every time.

 

[Nytrunner]

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

Or does that then make the motor "research".....

 

[Steve Shannon]

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

Or does that then make the motor "research".....

That’s basically what you’re doing. In my opinion it’s not a modification.

 

[billdz]

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.

 

[tim cubbedge]

Try a gun shop. Not all Walmart’s carry them. They’re made by Pyrodex. Cabellas or bass pro shop also carries them.

 

[billdz]

Something like this?
https://www.cabelas.com/product/sho...n-pellets-pellets-per-box/740965.uts?slotId=4

 

[tim cubbedge]

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

 

[Steve Shannon]

Something like this?
https://www.cabelas.com/product/sho...n-pellets-pellets-per-box/740965.uts?slotId=4

Yes. There are other brands also.

 

[billdz]

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

No issue, just trying to learn. What about the cannon fuse?

 

[jimzcatz]

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" .

 

[tim cubbedge]

What about the cannon fuse?

What is your ignition source?

 

[billdz]

What is your ignition source?

Ematch or CTI igniter

 

[tim cubbedge]

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