21st May 2008 05:19 AM
Launch Controller for high powered rocketry...
Hi I'm new here and to electronics building and my name is Jon. I'm currently in need of some assistance for a project I have envisioned. This project is for a launch controller for high powered rockets. I will list what needs to be incorporated below:
12Volt output from a 9.6Volt rechargeable battery.
An LED array telling the user what the current battery level
Another LED array telling the user when the bank of Capacitors are charged.
on / off toggle
safety on / off toggle
momentary push button for ignition.
speaker type screw terminals for wire going to rocket motor
I believe that is all that needs to be incorporated into the launch controller...I look forward to seeing what everybody thinks of this idea and how challenging it will be to build...Thanks for your time!
21st May 2008 05:50 AM
I was also hoping to incorporate a red and green LED to let the user know if the igniter is good without sending power to it and igniting it prematurly. The igniter I'm reffering to is a bridge wire type design, so i believe coninuity is the way to check it, i may be wrong though. It would also need a nice high amp load sent to the ignitor with 12V.
21st May 2008 08:18 AM
Use an 12V SLA gel type battery and you don't need to have capacitor banks to charge up.
A heavy duty 12V relay, and key switch to control its coil is the way to go for the final pre-ignition control. Once you have inserted and turned the key, the ignition will fire when the ignition push button is pressed with real current going into the igniter.
You can place high efficient LEDs across all normally opened circuit paths like contacts and keyswitch to monitor the continuity as 1~3mA would not trigger the relay or fire the igniter.
Last edited by eblc1388; 21st May 2008 at 08:19 AM.
21st May 2008 05:08 PM
I was actually kinda hoping for something a bit more complex. Is there a way to boost 9.6V to 12V? I know those batteries are fairly heavy and they don't fit the space requirment. Thats why I was hoping to use the 9.6V rechargable i mentioned.
21st May 2008 05:34 PM
Have you tried to launch with 9.6V, it's usually the current requirement rather than the voltage needed to ignite them.
21st May 2008 05:51 PM
as a matter of fact I have with success, but only with 10' or less of wire between the ignitor and the power source. Is there a way to boost this to maybe 100' just in case someone may have to be that far.
22nd May 2008 01:04 AM
I would like to know the necessary current flow across the ignition wire. It's quite easy to build a step-up converter to the desired 12V.
If you like I'll make a complete circuit for you including an extra safety feature like dual ignition buttons, far enough apart, not to initiate ignition inadvertantly, being forced to use two hands to operate the ignition circuit.
I've been model rocketeer for quite a while and even small rocket motors can cause severe injuries to persons standing near the launch platform.
For the ignition wire I usually use wolfram.
22nd May 2008 01:28 PM
Sounds like you have some serious problems with your battery if you can only get the igniter to fire on a 10 foot wire!!
Originally Posted by JonCherba
Are you using the Estes model ignitors, or a real ignitor for a real APCP rocket motor? I use Cesaroni Pro38 motors, and have had 100% success firing them on well over 150 feet of cable using a 9.6v pack...
Dont assume a 9v PP3 is gonna shunt enough current to fire an Estes type ignitor.. Aerotech Copperheads are equally nasty to fire reliably... If you are into HPR, you'll know they are called CRAPPERHEADS!!!
Get the specs for the ignitors you will be using, and look at the "ALL FIRE" current needed.. Then design your controller around that.
Making a launch controller too complicated is a recipe for disaster.. Too many things to go wrong, and if you are at the business end of a HPR motor, then it is gonna sting!!!
22nd May 2008 07:41 PM
I build Experimental sugar motors along with my own ignitors from a twisted pair cat 5 cable taken apart and i only use one twisted pair for each igniter, then i take a single strand of copper wire from a lamp cord or similar, im using old speaker wire. i run the strand through soem 2000 grit sandpaper to clean it then wrap the copper wire around one stripped end of the cat 5 cable and solder then wrap 5-6 times around the insulated part of the other twisted pair and solder at the end of the other twisted pair. then i wrap the igniter in fuse paper that i make and it works really well. no misfires yet. I was thinking about using nichrome instead of a strand of copper wire to possibly take the current needed down a bit. How can i figure out what the all fire is for this type of ignitor.
22nd May 2008 08:48 PM
Here is a page with some specs on nichrome wire if that helps any...
Aerocon Systems Nichrome Wire
I will more then likly be buying one of these sizes of nichrome wire...more then likly the 34 awg wire is what i will be getting...Here are the specs I'm assuming are the most important...
34 Gauge .0063" Diam. (0.16mm) 17.01 ohms per foot resistance...
Does this help at all? Thansk for all of the help...
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