I put them in the sustainer. The main reason for this is that I prefer to separate the stages before the sustainer motor lights.
That was what I was planning on doing.
If you put the staging electronics in the sustainer, there are a number of locations you could use. One location is between the motor mount and the airframe between the fins. There often isn't enough room for this though.
Yeah I was going to put the timer there.
Another option is to use the zipperless coupler approach and to put the electronics within the zipperless coupler.
I don't know what a zipperless coupler is..
The option I use it to put the electronics in the conventional ebay position and then run breakwires through the drogue bay.
That was something else I could do if it doesn't fit in in between the fins.
Your ignitor circuit should include a shunt that shorts out the ignitor. This is the last thing you open before leaving the pad, and I do it when no one else in around the rocket. You need to study up a bit on how to make shunts work properly (I use a small resistor in the ignitor circuit).
May I see how you do it just so I have all this info in (mostly) one place?
The other important thing is to use an altitude check before lighting the sustainer motor. You want to implement the logic "don't light the sustainer motor unless the rocket reaches at least xxx feet in less than yyy seconds". There are at least four altimeters that I'm aware of that can do this.
Which ones do this?
The approach requires that you do a simulation of the conditions where you want the sustainer ignitor to fire, and then choose a sensible trigger altitude and/or time so that the flight has to be nominal or the sustainer won't light.
How would I use rocksim to simulate separation? I know there is the ignition delay that I can use for the sustainer, but that doesn't seem to work the way I thought it did. That being said, I was planning on separation 0.1s after MECO and then ignite the sustainer 3s later.
Inhibited ignition is required at some fields, and it is easy to do. It is something you should do on your very first flight.
Yeah I figured it wasn't to difficult, I have worked with accelerometers before.
With respect to tracking, your basic options are RDF and GPS. GPS is getting more reliable, but it has not yet reached the reliability of RDF. I fly both, but if I had to choose one, it would be RDF.
What type of equipment will I need for RDF? Is it expensive? And would GPS be cheaper? If so I might sacrifice some reliability, as long as it can get me in the general area (I might put one of these on board:
https://www.apogeerockets.com/Electronics_Payloads/Rocket_Locators/Transolve_BeepX , or make something similar)
I'm not a big fan of fiberglass two-stagers because of the weight.
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Another way to save weight is to go single deploy in the booster, with electronics in the staging coupler. It is a good thing for two stagers to minimize the number of tube breaks.
I'd rather use fiberglass. I'm a little more familiar with it. Also if I go too light I might break the waiver. I'm going to use 22k as a goal and if simulations go too far below that when I have almost everything configured correctly, then I may consider dropping some weight.
As for dual deploy, the booster after staging sims to 4.5k. That's already higher than anything I've ever launched (that will change by the time I build this). It was going to be dual deploy from a single bay with the electronics in the coupler, using the cable cutter method.
Thank you for your very comprehensive response.