little help on launch controller functionality

[rocketdoctor99]

Im designing a 10 rocket launch controller based on some previous designs Ive seen on the world wide web. Im going to 10 3 way toggles that will either be in Off/Fire/Continuity for each pad, a Keyed Power Switch an Armed Switch and a Fire button. the question I have is Id like for the continuity check to work when the Power is turned on (with key ) but not require the Arm Switch to be turned on. Is this a bad idea does it remove a level of safety that I should keep.

 

[gudoldboy]

I built a 8 spot launcher this spring. Same principle you have mentioned. I use the power on key switch and master arm switch both for continuity checks. Seems to work quite well for me. I will see if I can find the thread I posted about it. A lot of very good info and advice from others.

 

[Solomoriah]

My four-position launch controller has four arming switches; when armed, the relevant continuity light will operate, but you have to put the key in before the ignition button works. My circuit can scale up to a larger number of positions easily. Is this anything like you are planning?

https://rocketry.gonnerman.org/launchsystem.html

 

[rocketdoctor99]

My four-position launch controller has four arming switches; when armed, the relevant continuity light will operate, but you have to put the key in before the ignition button works. My circuit can scale up to a larger number of positions easily. Is this anything like you are planning?

https://rocketry.gonnerman.org/launchsystem.html

Sort of my thoughts except I was thinking you need the key to turn on power to the system and check continuity. my thoughts here are that no even continuity power can go to leads until your safely at control panel. Im concern over faulty wiring/circuity causing a premature firing during continuity check. Im sure most likely any failure in circuitry would result in no power to the launch. Thanks for your plan details thats helpful. How did you put a screw at the end of launch Rod?

 

[Solomoriah]

Sort of my thoughts except I was thinking you need the key to turn on power to the system and check continuity. my thoughts here are that no even continuity power can go to leads until your safely at control panel. Im concern over faulty wiring/circuity causing a premature firing during continuity check. Im sure most likely any failure in circuitry would result in no power to the launch.

That was my original plan, but changing it to allow continuity testing with just the arming switch on was easy; as the continuity check uses an LED, there should not be enough current to fire even the most sensitive igniter (and I've tested with Q2G2 igniters with no problem).

Thanks for your plan details thats helpful. How did you put a screw at the end of launch Rod?

Using a drill press, drill a hole in a block of wood just large enough to screw the machine screw into. It helps to have drill bits in 1/64" steps to get just the right size. Switch to a 1/8" bit, screw the machine screw into the wood, and drill right down the Phillips slot. As you are drilling metal, you should have an appropriate oil to apply to keep the bit cool while drilling. After the screw is prepared, I clean it with soap and water to remove the oil, then after it is dry I slide it onto the rod and apply "hot" CA glue to the head end so it is drawn into the gap between the rod and screw. You could use epoxy instead.

If needed, removal of the screw requires a propane torch to melt/burn the glue away. Very simple.

 

[Solomoriah]

Incidentally, the screw threads get dirty and make it difficult to screw the nut in place. I've applied a Teflon wax lubricant, generally used as motorcycle chain lube, to the threads with good results.

 

[rocketdoctor99]

thanks, so this is a simple sketch of my control panel (with only 3 launch pad selectors shown) I'll be adding a few more LED indicators and a warning buzzer. Does this look OK?Im also looking for suggestions for connectors for the ignition leads. I plan on attaching them to launch pad and want to be able to disconnect from box and pad and coil it up and store it.

 

[Solomoriah]

The circuit looks good to me. Considering what I ended up with for connectors, I'm not going to make any suggestions on that subject...

 

[gudoldboy]

Looks good to me. About the same schematic I used. I'm on mobile so I can't link my build thread. I used 16AWG straded speaker wire for launch cables and RCA plugs and jacks. Works quite well.