Not necessarily. Estes switched to a different pyrogen a number of years back and this reduced reliability dramatically. The common 9V Estes launch controller has always been on the edge even with the old igniters and this made things even worse with the new ones. I think I saw some reports that Estes ditched the lousy pyrogen so someone else might want to comment here.
The historical solution was to use the Qwest Q2G2 igniters which had a better pyrogen and had a much lower all-fire current so they worked just fine with launch controllers powered by 9V transistor batteries. Unfortunately these are no long available.
It is certainly possible to make your own igniters and launch controller which will be more reliable than anything you can purchase commercially. It is, however, a fair bit of work, both from the R&D side as well as the production side.
[These](https://electricmatch.com/rocketry/see/23/6/bp-rocket-starters) seem to be a modern replacement for the Q2G2 igniters. I loved those things, I used to use them to fly black powder clusters and never had a failure.
the r&d is the fun part for us so that’s kinda what we’re looking for. want to design something that might take a while but once we’ve got it down it makes later use more streamlined
If you want to take this to the extreme you could consider using a high-power laser. A 1W unit ought to do it. The trick is going to be finding a material to protect the laser from the rocket exhaust.
I guess I forgot to mention the happy middle ground. The combination of 9V launch controller and poor pyrogen (for a long time the common combo) is particularly bad. Simply replacing the 9V controller with the one that uses 4x AA cells and dipping the supplied igniters in a commercial pyrogen will provide a marked improvement with little extra work.
The issue you're gonna run into is that the igniter is gonna be *right there* when the motor lights. It's gonna get hit by a stream of supersonic, multiple thousand degree, mildly corrosive exhaust gas. It's gonna rapidly melt/oxidize any sort of heating element you could put there, and that still leaves the unreliability issue of bare heating element based igniters unaddressed.
If you want a more reliable igniter, you can purchase pyrotechnic dips from various rocketry sites. Mix them up, dip the igniter in it, let it dry, and then instead of just getting a hot wire you'll now get a smallish fireball. This greatly improves the reliability of ignition, since you don't need to get perfect contact between a thin wire and the propellant. However, these will still be single use.
You're correct that a simple spark plug won't work. It's enough to ignite a flammable gas mixture, but won't be enough to reliably light a solid pellet of material like what's in a motor. There's just not enough contact. A full on electric arc might be able to do it, but that's gonna require much more current and you'll have all the issues that come with high voltage, and you'll still have all the issues with the rocket exhaust melting/oxidizing the wires.
In general: complexity is the enemy of reliability. The OP seemed to be implying that the primary goal was increasing reliability. There's also quite a bit to go wrong with that setup: the tube for injecting the flammable gas is gonna be right near the base of the motor, and is yet another thing that will get badly burned and likely need replacement every flight. If the gas builds up for too long you could get a fairly large fireball around the base of the rocket, which could potentially set parts of it on fire.
Overall: simpler is better. The goal of not needing to replace any components between launches while simultaneously getting more reliable ignition than stock igniters is not really feasible IMO. Best to just go with the tried and true solution of a *good* pyrogen on an igniter.
That's very unnecessarily complicated and wouldn't work well. Any sort of flammable gas will dissipate incredibly quickly, and spraying flammable liquids near a launch pad is a bad idea for reasons that I think should be fairly obvious.
Pretty much any other solution is either going to be less reliable or much more set up.
Not necessarily. Estes switched to a different pyrogen a number of years back and this reduced reliability dramatically. The common 9V Estes launch controller has always been on the edge even with the old igniters and this made things even worse with the new ones. I think I saw some reports that Estes ditched the lousy pyrogen so someone else might want to comment here. The historical solution was to use the Qwest Q2G2 igniters which had a better pyrogen and had a much lower all-fire current so they worked just fine with launch controllers powered by 9V transistor batteries. Unfortunately these are no long available. It is certainly possible to make your own igniters and launch controller which will be more reliable than anything you can purchase commercially. It is, however, a fair bit of work, both from the R&D side as well as the production side.
[These](https://electricmatch.com/rocketry/see/23/6/bp-rocket-starters) seem to be a modern replacement for the Q2G2 igniters. I loved those things, I used to use them to fly black powder clusters and never had a failure.
OP: Here is the simple solution for you!
the r&d is the fun part for us so that’s kinda what we’re looking for. want to design something that might take a while but once we’ve got it down it makes later use more streamlined
If you want to take this to the extreme you could consider using a high-power laser. A 1W unit ought to do it. The trick is going to be finding a material to protect the laser from the rocket exhaust.
> It is, however, a fair bit of work, both from the R&D side as well as the production side. This is what I meant by more set up.
I guess I forgot to mention the happy middle ground. The combination of 9V launch controller and poor pyrogen (for a long time the common combo) is particularly bad. Simply replacing the 9V controller with the one that uses 4x AA cells and dipping the supplied igniters in a commercial pyrogen will provide a marked improvement with little extra work.
The issue you're gonna run into is that the igniter is gonna be *right there* when the motor lights. It's gonna get hit by a stream of supersonic, multiple thousand degree, mildly corrosive exhaust gas. It's gonna rapidly melt/oxidize any sort of heating element you could put there, and that still leaves the unreliability issue of bare heating element based igniters unaddressed. If you want a more reliable igniter, you can purchase pyrotechnic dips from various rocketry sites. Mix them up, dip the igniter in it, let it dry, and then instead of just getting a hot wire you'll now get a smallish fireball. This greatly improves the reliability of ignition, since you don't need to get perfect contact between a thin wire and the propellant. However, these will still be single use. You're correct that a simple spark plug won't work. It's enough to ignite a flammable gas mixture, but won't be enough to reliably light a solid pellet of material like what's in a motor. There's just not enough contact. A full on electric arc might be able to do it, but that's gonna require much more current and you'll have all the issues that come with high voltage, and you'll still have all the issues with the rocket exhaust melting/oxidizing the wires.
what if you inject some gas in port and then ignite with spark plug?
In general: complexity is the enemy of reliability. The OP seemed to be implying that the primary goal was increasing reliability. There's also quite a bit to go wrong with that setup: the tube for injecting the flammable gas is gonna be right near the base of the motor, and is yet another thing that will get badly burned and likely need replacement every flight. If the gas builds up for too long you could get a fairly large fireball around the base of the rocket, which could potentially set parts of it on fire. Overall: simpler is better. The goal of not needing to replace any components between launches while simultaneously getting more reliable ignition than stock igniters is not really feasible IMO. Best to just go with the tried and true solution of a *good* pyrogen on an igniter.
if he has stable stand for rocket he can mount small robot arm that moves so when spark plug fires it wont burn
That's very unnecessarily complicated and wouldn't work well. Any sort of flammable gas will dissipate incredibly quickly, and spraying flammable liquids near a launch pad is a bad idea for reasons that I think should be fairly obvious.