Launch Controller Voltage Confusion

[mccordmw]

I'm a little confused about how the general consensus is that a 12V launch controller is needed to start the L1+ APCP motors. I'm only at mid-power level now and reading up a ton on HRP while getting ready to build my L1 certification rocket, so I'll profess ignorance here. The igniters I have are simple e-matches that I dipped in Quickdip pyrogen to give a nice, hot, long burn.

https://www.amazon.com/dp/B00RJRORBA/?tag=skimlinks_replacement-20

When performing tests, these ematches seem to ignite just fine using my 3 and 6V ignition boxes. If these ignite, I'm not sure why they wouldn't start one of my CTI 38mm or 54mm motors.

Can someone enlighten me? Thanks!

 

[rharshberger]

You can use less, however the long wires required for HPR (100' min) can induce losses sufficient that 3-6-9v wont do the job unless a relay box is use. Some HPR igniter require higher current. CTI uses low current ematches because they use a BP ignition pellet in their 24mm up to 54mm iirc.

 

[astrowolf67]

I think the 12 volt requirement stems from Copperhead ignitors, and, the common availability of 12 volt batteries. While most modern ignitors will be just fine with lower voltage, higher voltage, and more current availability sure won't hurt, especially if you are launching clusters. Plus, the added capacity will last longer on a full day's worth of launching.

 

[watermelonman]

I'm a little confused about how the general consensus is that a 12V launch controller is needed to start the L1+ APCP motors. I'm only at mid-power level now and reading up a ton on HRP while getting ready to build my L1 certification rocket, so I'll profess ignorance here. The igniters I have are simple e-matches that I dipped in Quickdip pyrogen to give a nice, hot, long burn.

https://www.amazon.com/dp/B00RJRORBA/?tag=skimlinks_replacement-20

When performing tests, these ematches seem to ignite just fine using my 3 and 6V ignition boxes. If these ignite, I'm not sure why they wouldn't start one of my CTI 38mm or 54mm motors.

Can someone enlighten me? Thanks!

Your Cesaroni 38mm and 54mm motors are a little unique. Many other motors require higher voltage, higher current ignitors.

 

[mikec]

For example, from the Aerotech Firstfire instructions: "Make sure that your launch controller power supply is capable of
delivering 12 volts at a minimum of 3 amps to the igniter."

 

[Handeman]

I think the "general consensus is that a 12V launch controller is needed to start the L1+ APCP motors." comes from a lot of people that use and support club launches. It is certainly possible to launch a L1 HPR that is a Class One rocket and doesn't require a waiver, most HPR rockets do require a waiver and the clubs have those waivers. They also have launch controllers that are built to handle almost anything someone may bring to launch. That is usually a 12 VDC system with a relay so the battery is near the pads.

Since most HPR are launched at club launches and clubs have heavy duty 12VDC systems to handle everything, I believe that is where that "general consensus" comes from.

 

[JoeG]

I'm not sure I subscribe to your supposition. If you were to ask on this forum, "What is required to light a L1+ APCP motor?" Answers would be all over the place. I doubt very seriously that there would be consensus. We like to offer differing opinions.

Yes, the majority of launch systems are 12 volt systems using high amperage batteries mostly for the ability to launch continuously and , as Handeman said, to be able to light any type of motor starter that was hooked up rather than any one type or size of motor. At a club launch as in most things we have to consider the least common denominator. If all the motors had e matches or Q2G2's we may be able to get by with just a few 9 volt batteries as found in your altimeter/stager.

Mark, the good news is that if you are using e matches you can be assured that most any launch system you use will be suitable for your purposes.

 

[RocketRev]

Hello Mark,

The other thing to think about is that most high power igniter manufacturers are making their igniters for use with 12V launch systems. The reason the manufacturers are building their igniters for 12V launch systems is that the vast majority of club systems out there are 12V systems.

How many clubs use 12V launch systems? I don't know, but I can tell you that every single club that I've ever flown with uses a 12V system. Even the clubs without Wilson F/X systems that I've flown with over the years all use 12V systems.

The one exception that I had experience with was the first year that the Kloudbusters debuted their new launch system at LDRS 12 (? I think it was LDRS-12?) they were having trouble with their design and they boosted the voltage to 24V in order to get it to work. It did work, but they had a lot of igniters that burned SO FAST that they failed to ignite the motors they were in. Before their next launch, they got their system design fixed and its been a 12V system ever since.

All of the multi-pad launch systems that I've built over the last almost 50 years have been 12V systems. And of course all of my Wilson F/X digital launch control systems have been built for 12v, again because that's the high power rocketry igniter voltage standard.

Yes, some of them will work with less voltage, but the vast majority of igniter manufacturers build igniters with 12V launch systems in mind.

Brad, the "Rocket Rev.," Wilson