A large ball valve should have better flow but it sounds like you are opening it manually. I don't see how you can open it fast enough. From the time my launch initiates until the rocket has separated from the launch tube is approximately 24 msec. You need a pretty quick wrist to fully open the valve in less than say 10 msec.
@Charles Murray-- Hooray for "Rocket Boys"! One of my favorite books and movies after "Apollo 13". Just as an aside, I wandered into the Engineering section of a tiny bookstore in Boca Raton, FL when, much to my surprise, I found a 1st edition of "Principles of Guided Missile Design". The very same book from which Homer and the Big Creek Missile Agency learned their fundamentals! I bought it no questions asked.
Dconner, if you are able to fix it with a 360 degree camera and sending the captured images at real time scenario with the help of small wifi transmitters are interesting. Then the project resembles like a miniature of NASA's Mars mission curiosity.
I like the use of an air cannon instead of rockets. I built a similar device, though mine is more of a giant tube. Also, how can you determine launch speed, and can you do so using a camera not mounted on the rocket itself? I want to see how fast the one I built shoots nerf darts. All I know now is that they can punch through an aluminum can like nothing. Anyway, I also like the idea of putting a camera on the rocket, as I've only seen that with commercial rockets that use solid fuel rockets to fly, not something like this.
The 360 degree video technique you linked to would make an interesting image of the flight area. If I had a camera with higher resolution it would be more practical. With the camera I have the resolution seems barely adequate for the field of view that I'm using.
Rocket Boys is one of my favorite movies because it makes a young, aspiring engineer look like a normal child instead of socially-awkward geek. Also...the video from this article appears to be taken in an area much like Coalwood in the movie.
For starters, the pressure drop across that valve, as shown, is quite a lot. Substituting a ball valve will improve the range quite a bit, and also save quite a few dollars, in addition to making the system independant of external power.
I built a system that used a discarded carbon-dioxide fire extinguisher tank, rated for 1800 PSI, which provided me with a better safety factor. I use a similar bicycle tire pump, which can provide over 120PSI air pressure. This allows things to fly much higher, and makes the flights much longer.
For aerial views this is an affordable alternative to Hexakopters -- just without the GPS control and RC.
For safety we could consider fiberglass and resin shield loosely placed around the launcher. And one could wrap 20 or 30 turns of fiberglass string helically around the rocket body in both directions and secure it with glue or resin.
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