Building your own launch controller + which type of engines to use in multi-stage

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Hi everyone!

So I want to get into mid-power rocketry, I've got the rockets selected and "in cart", but there's just one thing I'm not sure about. Is building your own launch controller doable? You just need to get some current through the igniters at around 12 volts and it should be fine, right? Or do I need something specific, that ex. an Estes launch controller has?
My second newbie question is. I've designed and nearly finished my 2 stage model rocket in OpenRocket. Which engines should I use for the booster stage? The one without any ejection charge ot the one with no delay and an ejection charge? The rocket is a relatively low-power one and the motors that would give me good results are C6 on both stages as suggested by the simulator.
 
Building your own launch controller is definitely doable. I’m sure someone will chime in with advice.

As for the staging question, you should use a motor with no delay or ejection charge in the booster and one with a long delay in the sustainer, e.g. C6-0 —> C6-7. If the two motors will be touching, you should tape them together with cellophane tape. If there is a gap between them, you should drill a vent hole to allow the pressure from the burning booster motor to escape.

Could you post the .ork file? That would help us make better recommendations.


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Hi again, thanks a lot for a very quick reply ;)

Here's the file. Please note that the whole rocket is designed to be 3D printed, so more complex shapes are in the real rocket comparing to its digital representation. For example, on the top of the booster stage there is actually a cone guiding the hot flames into the upper motor, not a tube. Just to clarify (new to rockets, sorry) the 0 at the end of the engines motor name states that it has no delay but it has an ejection charge or both are gone?

View attachment Gierasimienko.ork
 
-0 motors do not have delays or ejection charges, they burn from the nozzle end until the fuel burns through at the other end putting flames and flaming particles towards the second stage motor and igniting it.
 
-0 motors do not have delays or ejection charges, they burn from the nozzle end until the fuel burns through at the other end putting flames and flaming particles towards the second stage motor and igniting it.
So what is the difference between -0 motors and -P motors? Are there ones that have 0 delay and have an ejection charge?

Sent from my SM-G930F using Rocketry Forum mobile app
 
So what is the difference between -0 motors and -P motors? Are there ones that have 0 delay and have an ejection charge?

Sent from my SM-G930F using Rocketry Forum mobile app

I don’t think there are any motors with a zero delay and an ejection charge.

The difference between a -0 motor and a -P is that the -P is plugged. It can’t be used for a booster stage because it won’t shoot any hot stuff forward at the end of the burn to light the sustainer.


Sent from my iPhone using Rocketry Forum
 
Hi everyone!

So I want to get into mid-power rocketry, I've got the rockets selected and "in cart", but there's just one thing I'm not sure about. Is building your own launch controller doable? You just need to get some current through the igniters at around 12 volts and it should be fine, right? Or do I need something specific, that ex. an Estes launch controller has?
My second newbie question is. I've designed and nearly finished my 2 stage model rocket in OpenRocket. Which engines should I use for the booster stage? The one without any ejection charge ot the one with no delay and an ejection charge? The rocket is a relatively low-power one and the motors that would give me good results are C6 on both stages as suggested by the simulator.

I built my own launch controller using a sealed lead-acid battery. I've never had any issues with it, and it's MUCH better than the Estes one for the new Estes igniters. The one thing to make sure you have is some kind of key interlock with a continuity check light/buzzer/etc. Put the key in series with the battery and the button in series with that, with the light in parallel with the button and the alligator clips in series with everything. Does that make sense?

batt+_________key_______light________< >_____batt-
. . . . . . . . . . . . . . . . . .|__button__|

For 2 stage rockets, in addition to what others have said, I would start off with a B6-0 to B6-6, for a couple reasons:
-It will stay lower and stage where you can easily see it
-It'll get off the rod faster due to the lighter weight, so it'll fly straighter
-You won't have to chase it as far, especially if it leans into the wind as it will tend to

The only other thing is to avoid flying stagers in any kind of wind. They'll arc waaaay over and fly for miles.

Good luck!
 
For My launch controller I use one of my 3S RC Car batteries 5000mah 12.6V fully charged and tons of current capability - I launch everything from 13mm Estes to 29mm Aerotech reloads - never a problem - (30 - 40 launches on a fun day)

By launch controller has 3 toggle switches with LEDs and a bud red button - all in series so the red button wont go unless all 3 LEDs are lit. Same as the schematic above, x3 :)

the kids love it = starting on the first toggle 3 - 2 - 1- launch
 
For first flight, I recommend A8-5 in upper stage rather than a C, unless you have a REAALLLLY big field.
Don't ask me how I know this.

Straight Trails!
 
FWIW I would suggest a relay system if the leads are over 15' long. A friend of mine built a system that didn't work because the leads were about 30' long and the wire gauge was too small. It didn't have enough oomph to light a homemade motor starter.

Be sure that your continuity-check light does not draw enough current to ignite the motor starter.

Best -- Terry
Igniters are regulated items, as are e-matches. Rocket motor starters are not regulated.
 
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