Finished Building My Custom Launch Controller (and system)!

[Purkeypilot]

Well, it's finally complete! After a several week business trip, I start to finished my launch control system project today! Here are some pictures of the finished product(s)!

Here is the whole setup - Controller, 12 VDC Power Supply, Igniter Leads, and Controller Power Cables

Controller and Power Supply

Here is the bread and butter; The Launch Controller. I built it using a LMB Heeger 7" 007 Modular Project Enclosure. As you can see, it's a 3 switch system utilizing a 2 position, single-pole-single-throw key switch as an interlock (key removable in the "off"/safe position only), a two position, single-pole-single-throw toggle switch, and a three contact, single-pole-single-throw LED push button switch as the Happy Button. The internal wiring is all 18 AWG stranded copper primary wire. The only thing that is missing is my switch guard cover that ended up being discovered out of stock when the supply order was prepped and shipped. Hopefully it will arrive soon.

Slightly different angle...

Rear of the launch controller. I utilized 4 Johnson solder contact banana jacks.

Power Supply Unit. I built it using another LMB Heeger enclosure. I added the handle for convenience. It is a simple cabinetry handle from Home Depot. Again, 2 Johnson solder contact banana jacks were used.

Rear of the Power Supply Unit. The 2 10-24 screws hold 2 90 degree brackets on the inside that I used for a sort of battery retention system.

The power supply is a 12 volt, 6 Amp-Hour Scorpion motorcycle battery. Wire is 18 AWG stranded copper primary. 2 heat shrink #10 stud spade terminals and 2 knurled thumb screws for easy removal.

Side view. Here you can better see the bracket and 10" bungee cord that was knotted twice to reduce the effective length and increase tension.

Top: 15' Igniter Leads. Fabricated with 18/2 AWG stranded copper ripcord, 2" alligator clips, Johnson banana plugs, and 1/4" 3:1 heat shrink.
Bottom: 5' Controller Power Cable. Fabricated with 18/2 AWG stranded copper ripcord and Johnson banana plugs.

And for the last picture, here is the controller connected with the power supply, interlocked, and armed. The ignition switch is wired such that the LED acts as a stereotypical continuity check light. With the circuit closed through the LED, only 12/100 of an amp reach the igniter.

REALLY looking forward to getting it out and launching some rockets with it! I'll post an update with how it goes

 

[markg]

Looks great. I eventually want to build something like this to replace my Estes controllers. What's your estimated cost on the project?

cheers - mark

 

[TRFfan]

Nice. That looks really amazing.

 

[sghioto]

With the circuit closed through the LED, only 12/100 of an amp reach the igniter.

Nice looking launcher , but if my math is correct that's .12amp or 120ma of current through the igniter which is really high for a LED circuit. Should only need around 20ma.

Steve G

 

[Purkeypilot]

Nice looking launcher , but if my math is correct that's .12amp or 120ma of current through the igniter which is really high for a LED circuit. Should only need around 20ma.

Steve G

Haha! Ya, my bad, it was almost 3 am when I posted The schematic from Del City shows the LED drawing 20mA, and I just hooked up the Fluke and sure enough, it shows .014 amps/14mAs. Going to get it out later today with any luck!

 

[Purkeypilot]

Looks great. I eventually want to build something like this to replace my Estes controllers. What's your estimated cost on the project?

cheers - mark

Thanks much! I spent more on it than I thought I would and more than I should have, HAHA! The most expensive things were the enclosures and switches. The controller enclosure was about $35, which was worth it to me as it is exactly what I envisioned when I conceived the project. The Engine Start button was about $14, and again, it was exactly what I had imaged before I ever started so worth it. There were quite a few purchase situations that added to the cost of the project, and the majority of them were a result from having to essentially buy in "bulk" due to the nature of the items. The wire, terminals, knurled thumb screws, etc. was sold in minimum lengths and quantities respectfully. The ripcord I used for the leads and power cable was sold in a minimum of a 250' roll, which ended up being almost $40. I was cool with it, because I have it laying around now for other projects! What also increased the cost were the Scorpion motorcycle battery and I also purchased a Deltran Battery Tender Plus, which were $40 and $55 respectfully.

I think all said and done, I spend about $250 on everything. That being said, I could build a duplicate one right now (including power supply) for about $100-125 due to having so many materials left over. Good luck when you decide to start the project! It was a blast, and I enjoyed it easily as much as the actual act of flying rockets. If you have any other questions on cost, suppliers, parts or parts numbers, just send me a PM and I'll get back to you as soon as I can.

 

[Purkeypilot]

Field tested the launch control system yesterday! Worked flawlessly and as expected for 3 launches! I love, love, love building, finishing and flying rockets, but I definitely love designing and building custom GSE as well! Looking forward to building pads/rails and a HPR launch controller utilizing a relay as well in the future!