1 or 2 igniters ( per motor) for a 3 motor cluster?

[JDcluster]

I usually go with just 1 per motor but, on it's first flight; I got 2 out of the 3 to ignite in my Tri-Star.
The motors were about 5 years old; AT DMS I 140.
The rocket reach 2,000+ ft on the pair.
I was contemplating using 2 per motor but opted not to at the pad. I was afraid that they could clogg the nozzle and possibly CATO on the pad. I use the BKNO3 / Viton mix dip on Chinese e-matches.

It's the only one that has failed since I started dipping them.

I have another flight planned for this weekend's METRA October launch.
Motors this time will be three I 370's of mine own making; 38 mm x 480 Loki hardware.
82% solids freshly cored this week.

 

[Cameron Anderson]

Friends and I have discussed this at length...the consensus is that using two ignitors won't result in a CATO because one ignitor either lights and brings the motor to pressure and spits the other ignitor out, or the first fails and the second works and does the same thing.
Unless you're using a nozzle with a very narrow throat, 2 ignitors isn't an issue. Provided you have electronics to support 2 per, why not?

 

[Johnly]

An I-140 has a pretty small throat for inserting 2 igniters. A SU motor would preclude you from installing a pellet or sliver of BT to assist with ignition.
I've lit ancient motors with BKNO3, so perhaps it was just misfortune.

 

[Rocketjunkie]

Aren't I140s White Lightning? White lightning propellant gets hard to ignite (see old reloads with white Mg corrosion) over time. Redline is even worse. The other propellants age much better.
Sounds like your next flight will be on fresh Rx motors. You shouldn't have any trouble.

 

[JDcluster]

Yup, No problem this time around. I opted for 1 igniter per motor; 38 mm x 4 grain x 3.
I did test all 3 igniters with a meter before sitting it out on the pad. (I had 1 other flight this weekend where the igniter was bad.) All 3 motors lit with a nice straight boost and perfect recovery.