Model Rocket Ignition Controller

Intro: Model Rocket Ignition Controller

Having recently purchased a starter kit for an Alpha III Model Rocket I was unfortunately underwhelmed with the controller supplied in the kit. The main issue for me being the standard 9volt battery not producing enough power to the igniter to effectively light the engine and launch the rocket. The supplied controller is otherwise a good design (maybe a little flimsy) with the removable safety key which is great feature especially when children are around the launch area. The other problem is, well if your anything like me you will have no trouble losing that particular safety key. Instead of a removable key i opted for a dual action toggle switch and removable launch leads for safety.
My answer to the main issue was to build a more robust unit and beef up the power delivery. I was able to produce the following controller for around $35 including the Li-Po battery. Most of my supplies were purchased at my local Jaycar but I'm sure you could lower the costs buy purchasing online.

STEP 1: Collect Your Materials

All materials are shown in first photo except for the Zippy Compact 850mah Battery and panel mount fuse assembly which were added after my first version failed to impress with a standard 9volt battery.

Required Materials

- project box/ adaptable box (I used a 125mm x 65mm x 40mm box)

- toggle switch

- carbon missile style toggle cover

- red LED momentary push button

- battery (please check above link for the Zippy compact battery used)

- panel mount fuse holder

- 5amp glass fuse (added for short circuit protection with the inclusion of the LiPo battery)

- panel mount banana sockets (red & black - optional)

- 1mm flex building wire

- right angled spade lugs

- heat shrink (tape could also be used)

- twin cable such as speaker wire with banana plugs at one end and alligator clips at the launch pad end

Tools Required

- pliers for cable stripping and crimping lugs

- battery drill

- 13mm drill bit

- 6mm drill bit

- 20mm holesaw

- gas torch (if heatshrink is used)

- soldering iron & solder

STEP 2: Preparation and Layout

Preparation

Firstly I cut all of my cable to length and applied the relevant lugs and heat shrink. Also you may like to solder connections to the panel mount fuse and banana plug sockets prior to installing them in the panel.

Coming from an electrical background I'm big on insulation so all connections I have used heat shrink. You could also use plain insulation tape or not worry at all as long as clearances are ok at the component terminals.

You will also need to take your length of twin cable (speaker cable) and solder your banana plugs to one end and alligator clips to the other. The length of cable you use will depend how brave you are but I recommend at least 3-5 metres.

Layout

The exact layout can be customised to suit yourself. I decided to make mine like a playstation remote with a horizontal layout as seen in the intro picture. The toggle switch mounted to the left and the pushbutton to the right. The panel mount fuse is located in the middle towards the front edge.

The Toggle switch and panel mount fuse require a 13mm hole drilled, the pushbutton is mounted with a 20mm hole drilled using a hole saw. The banana plug socket are mounted on the leading edge of the controller and require a 6mm hole.

Depending on the Project box you use you may need to be fairly exact with your layout making sure to allow for battery installation and still being able close the lid once all is complete

STEP 3: Circuit Wiring

The wiring required is very simple and all the information required should be found in the attached pictures. My apologies for the rough wiring diagram, it is only intended as a guide and the symbols used may not be exactly right.

STEP 4: Completion and Test

Assuming you have arranged and wired all the components correctly you are now ready connect your battery (as an extra I made a small notch in the side wall of my project box to all for the charge/ balance plugs of my battery to be accessed externally), close your project box or should I say Launch Control Box and test your circuit.
You will have to attach your twin cable with banana plugs to the sockets mounted on the box and the alligator clips to a suitable size resistor (test purposes only) or sacrifice an actual engine igniter. If all is well what you will see should be something similar to the attached video clip.

Congratulations! you now have built a fully functional, powered up ignition control for you model rocket, now all that's left is to get out in the field and launch some rockets.

STEP 5: 5 4 3 2 1 Blast Off!!!

Comments

[scotshocker]

This is seriously nice. How large is the project box?

[AMGSARI]

Thanks for the comments, the box I used is 125mm Width X 65mm Depth X 40mm High. That was as compact as I could make it allowing for adequate space between components. The size of the battery you use will most likely be the main governing factor in the size box you require.

[scotshocker]

thank you for the information. I hope to build one of these soon.

[AMGSARI]

That’s great, let me know if I can help with anything else and please share the finished project.

[Zoom 475]

Is the light checking connectivity with the motor?

[AMGSARI]

Great idea, but unfortunately the push-button light simply indicates the battery is connected correctly and your ready to deliver the potential of the connected battery to the ignitor/ motor.

If you manage to modify the circuit I’d be interested in the wiring diagram

[krusty]

Love it :) How many launches do you get from a charge?

[AMGSARI]

Not sure and exact number. What I do know, I've launched a dozen rockets and the li-poly still shows full charge. My bet is your rocket engines run out before the battery does.

If you actually build it or something similiar I'd be interested to hear your results

[krusty]

LOL I dunno.. I have a few rocket motors ;)

I currently have 2 12v launch systems that are a bit bulky to lug around for low power launches, so am def. looking to build something like this. I'll post photos etc. when I get to it! Thanks for the answer!!

[Heyup]

That looks cool, what are you using to ignite the firework please?

[AMGSARI]

Thanks Heyup, the ignitors i am using atm are the standard ESTES igniters found here http://www.estesrockets.com/rockets/engines/flight-supplies/002302-model-rocket-starters. If your purchase ESTES rocket engines they are also supplied in the pack.

[Toby Robb]

Great instructable, easy to follow and with good pictures, i like it!

[AMGSARI]

Thanks Toby for your encouragement, I'm glad you enjoyed it

[RandyPerson]

Nice, neat package. I especially like the battery. When I built mine, they didn't exist, so I have heavy leads to clamp to an external battery. Here's an alternative for the banana plug and dedicated fire wire. I like to stand way back, not as much for safety as to get a better view of the launch and flight. It also gets the kids well away from the launch pad, as they really like to fire the rocket. I use a standard AC extension cord for the connection. At the controller, use a short length of cord with a female replacement cord end. At the launch pad, a short pigtail with a male plug and a couple small alligator clips makes the final connection. Then just grab your 25 or 50 foot outdoor cord when you head for the range, and you're all set.

[AMGSARI]

Thanks for your feedback and ideas. A better view is always good, those rockets get out of sight really quick.

[SpaceBuckaroo]

I have an idea for an improvement. Include a speaker and digital readout. When you push the button, the counter starts counting backwards with an audio voice counting 10, 9, 8, 7, 6, 5, 4, Ignition (with some Apollo rocket noises), 2, 1, liftoff (rocket launches).

[AMGSARI]

Thanks, that's a great idea. I actually looked into installing an audio file countdown but I wasn't able to fit it into the slimline project box I went with.

[boukhtache]

nice thanks

[Prfesser]

For a cheap, removable, easily replaced key (removable = impossible for someone to accidentally launch while you're at the pad), wire an ordinary wall socket in place of the safety switch. Use a plug from an old extension cord as the key; twist together the wires from the plug to short the plug. Not as pretty as your solution but it works.

Nice instructable, neat execution!