Julianconde
Active Member
For HPR how much current is needed to ignite the motors. A-K ??
HPR launch controller
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Scott_650
Well-Known Member
Our club systems - our launches are combined Tripoli/NAR - both use 12V vehicle batteries, a motorcycle sized gel cel for the LPR rack and car/truck sized battery for the HPR pads. I don’t know what AH or CCA rating either has - sorry - but we’ve never had them fail during an all day launch session. My Estes #2240 PSII Controller uses 6 C cell sized batteries and has easily fired up any H motor and below I’ve used, even with cheapo bought on the fly convenience store alkalines.
waltr
Well-Known Member
All the basic igniters are the same to get them lit. It is just the amount of pyrogen on them for different size motors.
Most are rated to fire at 1Amp of current and I would ensure the system can supply 2Amps total.
Now if long leads you need to ensure the Voltage is high enough to still have over 1Amp through the igniter after the Voltage drop through the wires.
The big difference for High power is the distance from controller to the pad. A long run of wire can have a significant Voltage drop lower the current to the igniter.
Most are rated to fire at 1Amp of current and I would ensure the system can supply 2Amps total.
Now if long leads you need to ensure the Voltage is high enough to still have over 1Amp through the igniter after the Voltage drop through the wires.
The big difference for High power is the distance from controller to the pad. A long run of wire can have a significant Voltage drop lower the current to the igniter.
These links might address your specific question.
https://www.apogeerockets.com/education/downloads/Q2G2_Igniter_Report.pdfhttps://estesrockets.com/wp-content/uploads/Educator/2811_Estes_Model_Rocket_Launch_Systems.pdfhttp://www.privatedata.com/byb/rocketry/Ignitor/igniters.pdf
In general, what Walt has suggested is true. Also, if you have long cable runs out to an HPR pad, then use heavy gauge wire and a beefy battery that can accomodate the extra wire losses. Better still, use a relay-based pad unit.
Getting the igniter to ignite is only half the story; you need the correct igniter to ignite the motor. Some HPR motors require more energy from the igniters to get them going. If you're using motor reloads, then it is relatively easy to expose some fresh propellant at the top of the core of the upper grain to assist with reliable motor ignition (particularly with old grains). If you're using single-use motors it's a little harder. Sometimes you might need to substitute the igniter provided for a better one (more pyrogen), or use more than one.
https://www.apogeerockets.com/education/downloads/Q2G2_Igniter_Report.pdfhttps://estesrockets.com/wp-content/uploads/Educator/2811_Estes_Model_Rocket_Launch_Systems.pdfhttp://www.privatedata.com/byb/rocketry/Ignitor/igniters.pdf
In general, what Walt has suggested is true. Also, if you have long cable runs out to an HPR pad, then use heavy gauge wire and a beefy battery that can accomodate the extra wire losses. Better still, use a relay-based pad unit.
Getting the igniter to ignite is only half the story; you need the correct igniter to ignite the motor. Some HPR motors require more energy from the igniters to get them going. If you're using motor reloads, then it is relatively easy to expose some fresh propellant at the top of the core of the upper grain to assist with reliable motor ignition (particularly with old grains). If you're using single-use motors it's a little harder. Sometimes you might need to substitute the igniter provided for a better one (more pyrogen), or use more than one.
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A-P+ motors are all about the same current needed. As @waltr said, it's the amount of pyrogen that's different. I use a ematch and .50 cal Pyrodex pellet for my EX M motors so that probably needs less current than Estes igniters.
caveduck
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Not all HPR starters need the same current. CTI motors use e-matches that have 500mA all-fire current, and fire pretty much instantly due to the pyrodex pellet at the top of the motor grain stack. Aerotech starters take 1-2 Amps and are often far from instantaneous, so you will consume quite a bit more battery charge with those. Either way, a 2000-3000 mAh LiPo will fire a lot of rockets.
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