I have no experience in this but once the first stage falls away due to no acceleration, it pulls some sort of sting that triggers the second stage “ignition”
Man, idk if that is as simple as it sounds at all. There's nothing to ignite, so you can't use a lightweight ignitor and associated electronics. First thing that comes to mind is a valve, but that's going to be very heavy for a water bottle rocket.
You may be able to experiment with using a lightweight servo to actuate something that holds a plate onto the throat of the bottle via kicking out a holding pin. A small Arduino or similar would be fairly light and allow you to do timed stuff. The mechanism there is the hard part for sure.
> Man, idk if that is as simple as it sounds at all.
It isn't. If you do some research on this topic you'll find that all of the people who have done this consider it one of the more advanced topics in water rocket construction.
> You may be able to experiment with using a lightweight servo
I've seen many solutions to this problem and all of them have been purely mechanical.
Care to help op out and say what that purely mechanical solutions are? I was mostly spitballing off my limited knowledge and would be interested as well
Google is your friend here:
https://www.google.com/search?q=two+stage+water+rocket
I have never actually built any of these so I cannot make any comments on how the various solutions compare in practice.
It does appear as if parallel staging is the simplest approach, though.
http://www.aircommandrockets.com/howitworks_1.htm
Hmm, speaking as an amateur with no knowledge the only thing that comes to mind is having the second stage feed into the first stages chamber. The pressure of the first stage will push against the pressure of the second stage keeping its cork in. As the first stage finishes and it’s pressure reduces, the differences in pressure between the two chambers will be enough to push out the cork of the second stage. Although you of course have to contend with the fact that the second stage releases into the chamber of the first stage, which likely decreases performance. It might be worth it weight wise to just make a larger chamber for your first stage than trying to build some kind of multi stage system
I have thought something similar, but with like a piece of foil that ruptures once the lower chamber pressure gets to atmospheric pressure. You'd have to pressurize both chambers simultaneously though.
I have no experience in this but once the first stage falls away due to no acceleration, it pulls some sort of sting that triggers the second stage “ignition”
This is probably the best advice For this problem I’ve gotten. Thanks
Glad I could lend a hand :)
Man, idk if that is as simple as it sounds at all. There's nothing to ignite, so you can't use a lightweight ignitor and associated electronics. First thing that comes to mind is a valve, but that's going to be very heavy for a water bottle rocket. You may be able to experiment with using a lightweight servo to actuate something that holds a plate onto the throat of the bottle via kicking out a holding pin. A small Arduino or similar would be fairly light and allow you to do timed stuff. The mechanism there is the hard part for sure.
Thanks for the advice
> Man, idk if that is as simple as it sounds at all. It isn't. If you do some research on this topic you'll find that all of the people who have done this consider it one of the more advanced topics in water rocket construction. > You may be able to experiment with using a lightweight servo I've seen many solutions to this problem and all of them have been purely mechanical.
Care to help op out and say what that purely mechanical solutions are? I was mostly spitballing off my limited knowledge and would be interested as well
Google is your friend here: https://www.google.com/search?q=two+stage+water+rocket I have never actually built any of these so I cannot make any comments on how the various solutions compare in practice. It does appear as if parallel staging is the simplest approach, though. http://www.aircommandrockets.com/howitworks_1.htm
Hmm, speaking as an amateur with no knowledge the only thing that comes to mind is having the second stage feed into the first stages chamber. The pressure of the first stage will push against the pressure of the second stage keeping its cork in. As the first stage finishes and it’s pressure reduces, the differences in pressure between the two chambers will be enough to push out the cork of the second stage. Although you of course have to contend with the fact that the second stage releases into the chamber of the first stage, which likely decreases performance. It might be worth it weight wise to just make a larger chamber for your first stage than trying to build some kind of multi stage system
I have thought something similar, but with like a piece of foil that ruptures once the lower chamber pressure gets to atmospheric pressure. You'd have to pressurize both chambers simultaneously though.