2-Stage Bug - II

[Rocketclar]

Still working on design and developing questions with potential solutions for a 2-stage project. Trying to anticipate problems and how to avoid them. While I have found a few 2-stage kits out there, I’m strongly leaning for scratch build. I will try to incorporate error proofing designs to minimize mistakes. All of my rockets are numbered and I keep track of all flights in a spreadsheet. This rocket will be number 100 in the fleet that I’ve built over the decades from mod rocs to HP.

So my questions now are on the separation charge vs just relying on drag separation. I’ve found here that people use about 0.5 gms 4F (I will ground test when built.). Anyway, I assume the charge is placed at the top of the ISC and controlled from the ISC “fired” via another timer. What are your design attributes to minimize fouling the ignitor and motor in the sustainer? Other words of wisdom? Thanks!!!

 

[Cameron Anderson]

Gorilla tape over the sustainer nozzle is all I do and I haven't had any issues.

 

[Rocketclar]

Thanks. I like easy.

 

[Banzai88]

Gorilla tape as in a piece of duct tape?

 

[Cameron Anderson]

Gorilla tape as in a piece of duct tape?

Yep. A small piece over the end cap to keep separation charge gasses out and to keep your ignitor in. I like gorilla tape because it tends to be thicker and hold up better versus other tape.

 

[Bamraam]

I used a friction fit to attach the sustainer to the booster. Booster has a camera facing upward and the sustainer has a camera pointed downward. Booster and sustainer are 4" and have identical size and number of fins.
On the first flight I relied on drag separation, but that didn't occur (guess that's why most boosters have oversized fins?), instead the ignition of the motor separated the booster, and due to having a Smokey Sam motor in the sustainer, the smoke blacked out the camera lens on the booster.
Second flight I used a timer with 0.5g of BP for a separation charge. But again the ignition of the motor separated the booster rather than the separation charge. After recovery I confirmed charge had fired, so I assumed the booster and sustainer separated at least enough to prevent the separation charge from being effective.
Third flight they say is the charm, I did everything the same as the second flight exept i used masking tape to hold the booster and the sustainer together, and voila, it worked as planned, well at least the separation. The sustainer lost it's plywood fins on this flight due to a little too much acceleration.
I just used a couple of layers of masking tape to cover the nozzle, and laid a sheet of kevlar inside the booster/sustainer coupler over the separation charge.
I did all this several years ago and still haven't rebuilt the sustainer, but have all I need to rebuild all fiberglass.