From a very young age, I have always wanted a model rocket. And that dream came true.
It seems whenever I get together with my good friend Adam (who is as immature as me!) we seem to do the most spontaneous things. It started with an idea and then we decided to drive to town and buy a rocket kit. Why not!
Anyway, the kit we bought was a bog-standard (that is, common-variety) (t)Estes Patriot launch set. It’s “Patriot” because it has US Army plastered all over it. It probably serves as an additional warning as it may it fly back and hit you. Unfortunately, it was the last one, so we had to make do with a friendly-fire rocket. The kit consists of a rocket, the launch pad and the electronic igniter. The rocket motors had to be bought separately with ID.
The rocket was just a cardboard tube with plastic fins and a nose cone. Its completely hollow inside. The launch pad was just as simple as it was a plastic stand with a metal rod which supported the rocket before launch. The most intriguing part (for me) was the igniter. I was curious as to how it worked. Not wanting to crack it open and destroy it, I searched upon Google for “Estes Electron Beam”. The igniter itself costs £10 if bought separately, which is an absolutely extortionate price when I found out what was inside it. Just metal contacts… no electronic components whatsoever. Disappointing. Below is the schematic:
I have tried to replicate the electron beam as closely as I can. On the left are 3 cells which should be 4 as it takes 4AA cells but it doesn’t matter. The LED is actually an incandescent bulb which I couldn’t find in my library. BB1 is the busbar which connects to the long leads which eventually link up to the igniter in the rocket motor. S1 is the “key”, which acts as a safety precaution—it needs to be inserted and pressed down firmly, otherwise S2 will not work, as they are in series. S2 is the launch button. As you can see, the the circuit is an extremely simple one. I thought I would take it upon myself to tart it up a little and have a launch system that’s a bit more satisfying that the silly thing it came with.
The electron beam uses 4 AA cells which is equal to 6V. I decided 4 AA cells would take up too much room so I replaced it with a single 9V cell. This doesn’t make a large difference in this application, despite 4 AA cells having more mAh as the electricity is only used to ignite the motors which don’t require much voltage or current. Below is my version of the igniter—it’s just as simple but far more satisfying:
The battery is now a 9v cell (G1), there is a power LED (in green obviously) to indicate that the circuit is on. This is directly connected to the power source, so, whenever there is a power source, the LED is lit. There is a current limiting resistor to stop the LED burning out. S1 is a toggle switch which is perfect to serve as an ARM switch, which you flick to turn on. The second LED is to indicate that the ARM switch is on. This LED is red. S2 is a SMD switch which switches off when released unlike S1. When both switches are on, the circuit completes and a current is sent down the long wire to ignite the motor. This was just a prototype on a breadboard, which worked extremely well. I plan to add flashing buttons and a switch guard to make it that much more awesome.
In the next part I will show the prototype version built up. This is just to test the concept without having to use a main power supply. Stay tuned, folks!