New Member - New Rocketeer - 1st Build

[Absolutely_Possible_Maybe]

Hello all,

( INTRO )
Jonathan here from Southern California, a.k.a. the sunny place for shady people (he-he). I have a 4-year-old son and I thought it would be a great hobby to start building models with him, with the hope that he enjoys doing things mechanically like his Father (me). I started us off with a moderate challenge by building out the Estes Boosted Bertha 2-stage. The build went well with the exception of some minor confusion on the engine housing. I was confused about the vent plug placement inside the tube and it's a tight fit, but the engine still fits and the threads accept the bottom PVC retainer lug/screw.

( PROBLEM/QUESTION )
The real problem came when I tried to figure out how to wire in my launch controller to the engine starter(s). I could not find any beta online and no youtube videos showing the wiring and where to wire the ignition module to the starter(s). The 2-stage rocket is stacked vertically and is a moderately tight slip joint connection, which is to detach when the 2nd stage ignites. I ("we - sorry Goose, WE") used C6-5 for the main engine and the C6-0 for the booster engine. I thought the engines would need to fire simultaneously so the engine with no time delay fires right away and just as it's exhausted the 2nd stage would be done with its time delay and would ignite??? I was obviously not right about this and the darn thing never did fire! I used some thin gauge 22ga. copper wire and soldered the wire to daisy chain the igniters for 1st and 2nd stage. I found the igniters did in fact burn, but the engine didn't catch fire.

( RESOLUTION )
The instructions only show the igniter to be plugged into the 2nd stage (bottom) engine. If this is the case, and no igniter/starter is to be wired up for the main engine (upper), does this mean that the upper stage gets lit from the bottom stage burning its way up to the top engine? if so, which engine should be placed where? do I want the engine with the time delay (C6-5) to be the bottom engine where the ignition controller and igniter will be wired together, and the upper stage rocket engine (C6-0) is not wired into the controller and will get its ignition from the bottom stage burning its way up?

Thank you,


-Jonathan & Ryker - (my son)

 

[neil_w]

Hello all,

( INTRO )
Jonathan here from Southern California, a.k.a. the sunny place for shady people (he-he). I have a 4-year-old son and I thought it would be a great hobby to start building models with him, with the hope that he enjoys doing things mechanically like his Father (me). I started us off with a moderate challenge by building out the Estes Boosted Bertha 2-stage. The build went well with the exception of some minor confusion on the engine housing. I was confused about the vent plug placement inside the tube and it's a tight fit, but the engine still fits and the threads accept the bottom PVC retainer lug/screw.

( PROBLEM/QUESTION )
The real problem came when I tried to figure out how to wire in my launch controller to the engine starter(s). I could not find any beta online and no youtube videos showing the wiring and where to wire the ignition module to the starter(s). The 2-stage rocket is stacked vertically and is a moderately tight slip joint connection, which is to detach when the 2nd stage ignites. I ("we - sorry Goose, WE") used C6-5 for the main engine and the C6-0 for the booster engine. I thought the engines would need to fire simultaneously so the engine with no time delay fires right away and just as it's exhausted the 2nd stage would be done with its time delay and would ignite??? I was obviously not right about this and the darn thing never did fire! I used some thin gauge 22ga. copper wire and soldered the wire to daisy chain the igniters for 1st and 2nd stage. I found the igniters did in fact burn, but the engine didn't catch fire.

( RESOLUTION )
The instructions only show the igniter to be plugged into the 2nd stage (bottom) engine. If this is the case, and no igniter/starter is to be wired up for the main engine (upper), does this mean that the upper stage gets lit from the bottom stage burning its way up to the top engine? if so, which engine should be placed where? do I want the engine with the time delay (C6-5) to be the bottom engine where the ignition controller and igniter will be wired together, and the upper stage rocket engine (C6-0) is not wired into the controller and will get its ignition from the bottom stage burning its way up?

Thank you,


-Jonathan & Ryker - (my son)

Welcome!

The upper stage motor is the C6-5, and the booster motor is the C6-0. The booster motor will light the upper stage motor. So you load the two motors, insert the igniter into the C6-0 booster motor, and then you're ready to go.

However, if you're just starting out, then I would strongly recommend that you get acquainted with flying the model as a single-stage *before* you try the multi-stage. There are far more things that can go wrong on a two stage rocket, so it's better to be certain you have all the fundamentals down before trying the two-stage.

Finally: for first flights use the smallest recommended motors. Sucks to lose the rocket on the first flight.

 

[Hobie1dog]

 

[kuririn]

Neil nailed it.
Check this article for more detailed info.
https://www.apogeerockets.com/Tech/How_2-Stage_Rockets_Work
Basically, when the top of the burning propellant mass becomes thin enough, the pressure breaks through sending a jet of hot gasses and burning propellant into the nozzle of the sustainer motor, igniting it. So, you only need an igniter in the booster (-0) motor.



Too much fun.

 

[smstachwick]

Neil nailed it.
Check this article for more detailed info.
https://www.apogeerockets.com/Tech/How_2-Stage_Rockets_Work
Basically, when the top of the burning propellant mass becomes thin enough, the pressure breaks through sending a jet of hot gasses and burning propellant into the nozzle of the sustainer motor, igniting it. So, you only need an igniter in the booster (-0) motor.

View attachment 523803

Too much fun.

A word I should say about this: this technique only works with black powder motors. That’s Estes motors, mostly, the ones with the paper cases.

Advanced composite motors also exist with more powerful propellant, but they must be ignited electrically from the top end, otherwise the delay won’t work properly. Staging composite motors requires electronic altimeters and accelerometers specially designed for the job.

I will reiterate what Neil said though: it’s wise to run a test flight with the smallest recommended motor, gradually increasing power and/or adding the booster after you verify that everything in the sustainer (the upper stage) works properly.

 

[Absolutely_Possible_Maybe]

Welcome!

The upper stage motor is the C6-5, and the booster motor is the C6-0. The booster motor will light the upper stage motor. So you load the two motors, insert the igniter into the C6-0 booster motor, and then you're ready to go.

However, if you're just starting out, then I would strongly recommend that you get acquainted with flying the model as a single-stage *before* you try the multi-stage. There are far more things that can go wrong on a two stage rocket, so it's better to be certain you have all the fundamentals down before trying the two-stage.

Finally: for first flights use the smallest recommended motors. Sucks to lose the rocket on the first flight.

Thank you for the great information!

 

[prfesser]

Estes' "Classic Collection" has their Technical Reports on the basics of stability, multi-staging, clustering, boost-gliders, etc. They deal only with blackpowder motors, and some of the info is bit out of date---but still useful. Their Technical Manual is a bit skimpy on those subjects but more up-to-date, and has info on construction and finishing as well.

Last year I watched a guy fly his first two-stage rocket. Apparently he had no knowledge of multistaging apart from the info in the kit itself. So...a D12-5 in the booster.....and a lawn dart.....

 

[kuririn]

Last year I watched a guy fly his first two-stage rocket. Apparently he had no knowledge of multistaging apart from the info in the kit itself. So...a D12-5 in the booster.....and a lawn dart.....

Was it an Estes kit? Estes (and most manufacturers) always recommend a -0 motor for the booster stage.

 

[prfesser]

Was it an Estes kit? Estes (and most manufacturers) always recommend a -0 motor for the booster stage.

It was, but I strongly suspect that, since he'd flown a bunch of single-stage rockets, he probably didn't bother to read the instructions that thoroughly.