Best Simple 12 Volt Launch Controller for Single Rocket Launch, But 4 BP Cluster Capacity

[lakeroadster]

I'm contemplating if I should build or buy a launch controller?

Mostly for LPR, just single rocket launches. Need capacity for (4) Cluster launch of BP motors. blackjack2564 has me just about talked into e-matches.

No bells and whistles, just something very basic. I'll use my 12 volt pickup truck battery for power.

Any suggestions on commercial units?

 

[prfesser]

A basic launch system for one rocket, BP motors with maximum of F impulse, need not be complicated. If you're not going to use a relay system, be sure that your cable from battery to pad is heavy enough to handle the amps needed. A friend found out that a 12v battery didn't have enough oomph to light a starter through 50 feet of 20 ga wire...

I did a quick-and-dirty controller with a pushbutton I had in the scrap box for launching and used a single wall socket as the safety interlock. A plastic single wiring box held the button and socket. The "key" was a plug from an old extension cord, with the wires soldered together. No continuity check. If it didn't launch, wait a minute and investigate.

Best -- Terry

 

[lakeroadster]

A basic launch system for one rocket, BP motors with maximum of F impulse, need not be complicated. If you're not going to use a relay system, be sure that your cable from battery to pad is heavy enough to handle the amps needed. A friend found out that a 12v battery didn't have enough oomph to light a starter through 50 feet of 20 ga wire...

I did a quick-and-dirty controller with a pushbutton I had in the scrap box for launching and used a single wall socket as the safety interlock. A plastic single wiring box held the button and socket. The "key" was a plug from an old extension cord, with the wires soldered together. No continuity check. If it didn't launch, wait a minute and investigate.

Best -- Terry

Thanks Terry!

I'm thinking about simply using 120V extension chords... I've got a bunch out in the barn. And then making adapters that plug into them, one at the truck battery, the other at the rocket. The adapter at the battery will have a switch. Seems like that would work? I hate buying stuff when I have stuff here that will work.

 

[prfesser]

Thanks Terry!

I'm thinking about simply using 120V extension chords... I've got a bunch out in the barn. And then making adapters that plug into them, one at the truck battery, the other at the rocket. The adapter at the battery will have a switch. Seems like that would work? I hate buying stuff when I have stuff here that will work.

A lot of clubs use those extension cords with relay systems. A relay system has a big battery near the pad, attached to the clips thru a relay. The controller at the other end of the cord doesn't supply the juice to the match or whatever; when the button is pushed it activates the relay (much less current needed) that closes the circuit to the match. That kind of system is more complicated.

Sounds like you need a simple system where the juice goes from battery thru cord to the clips. If you're only lighting up to G motors your cord shouldn't be much longer than 25 feet (14 ga wire). If it's too long you don't get enough amps thru the wire to the motor. NAR has a simple system shown on their site.

https://nar.org/NARTS/mahler/ultra.html

Best -- Terry

 

[shreadvector]

Needs to be 30 feet per the MRSC. Thick wire does the trick. A heavy duty extension cord has thick wire.

You can buy the Estes E controller and bypass the battery compartment and use your proposed battery instead of the 4 AA alkaline batteries. Plenty of amps will travel through that heavy wire.

Another option is the Estes Pro Series controller with the external battery cable. The connector seems tiny, but it is designed for clusters.

https://estesrockets.com/product/002240-pro-series-ii-launch-controller/

https://estesrockets.com/wp-content/uploads/Instructions/002240_PRO_SERIES_II_LAUNCH_CONTROLLER.pdf

oops, instructions are AWOL.

 

[DaveW6DPS]

I posted this in the Ground Support forum. It is fairly simple, and can be used with 50 or 100 foot Cat 5 cables.
https://www.rocketryforum.com/threads/arduino-continuity-circuit-and-low-power-launcher.151754/

 

[neil_w]

Estes Pro Series Controller would do the trick. It's quite nice. If you want to invest in a LiPo pack for it then it'll have plenty of juice to do whatever you want. Or you could do your 12V hookup scheme, as desired.

[doh... didn’t see shreadvector already suggested this]

 

[Ez2cDave]

https://estesrockets.com/wp-content/uploads/Instructions/002240_PRO_SERIES_II_LAUNCH_CONTROLLER.pdf

oops, instructions are AWOL.

Got you covered, Fred . . .

https://www.apogeerockets.com/downloads/PDFs/07707-PSII-Controller-instr.pdf

Dave F.

 

[mbeels]

I built one into the bottom of my tool box. I don't like carrying extra boxes if I don't have to. The side of my rocket tool box has the button and continuity light built-in, and everything I need for launching, including the estes launch pad, fits in the tool box.

 

[caveduck]

You can fire 3-4 motor clusters through 30-40 feet of wire as long as you control the resistance in the controller. The wire is less of a limitation than you think. 16-18 gauge wire should be fine. Extension cords are convenient and easy to find. Even the indoor types are usually at least 18 gauge.

A decent controller should have < 1.5 ohms total resistance, which will produce nearly 10 amps with a 3S LiPo or a healthy 12V lead-acid battery. Watch out for connectors and switches that have too much resistance - check with a meter. Also don't forget that batteries have internal resistance which limits the total current delivered. A lead-acid battery has pretty low resistance (< 0.1 ohm) when new but can approach 1 ohm near the end of life, which will cut the current to the ignitors by half. LiPo batteries have ridiculously low internal resistance, making them a better choice for clustering.