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Posted: Fri Jan 19, 2007 3:47 am
by Silence
I didn't really explore their formula(s), just the calculator on the site. Pretty neat! Ben has tried to come up with a way to calculate the ideal length before, but it became too complicated too quickly. What we do know is that longer is nearly always better, as the lengths are generally past the limits of pneumatic launchers*. But that's why I recommend a much smaller PC and a longer barrel, for less pumping--but I have yet to build something.

Yup, nested pumps help, but you don't want too many. That would add excessive complexity, especially if a certain stage is already only a few inches long. Try going for a smaller PC/less pressure. ;)

*On a sidenote, if anybody here watches Mythbusters, you might have seen their system to generate winds to send a reed through a palm tree. Not exactly a launcher, but really long, and nobody else is insane enough or rich enough to build one.

Posted: Fri Jan 19, 2007 5:34 am
by TheEngineer
Oh sweet jebus. Well, after hours of work. I found that it is impossible to do what I wanted.

Unless I can stretch my arms out 4 feet. HA!

I think what is happening. Is that the volume to pressure that I need is on the edge of an asymptote for the pumping ability. Lesson learned. However I will still probably get to working on my launcher idea again. Its just too irresistable. I will also work on some plans on a water gun. Not sure how thats going to pan out. But I have high hopes.

However, I will send my excel worksheet to anyone that wants it. Its got alot of good info on it.

Also, does anyone have any formulas for multiple pumping?

Posted: Fri Jan 19, 2007 11:25 am
by SSCBen
You have to follow an algorithm to do more than one pump. Basically, just do one pump to find out the pressure and volume of the chamber first off and then use those numbers again to find out the volume of the second pump. Tedious, but it's the easiest way to do it.

Posted: Wed Mar 14, 2007 7:46 pm
by C-A_99
Hey, it's pi day.

Sorry, random and relatively pointless post but I just had to get it out.

Re: Pump Forces, and Pressures

Posted: Mon Nov 26, 2007 4:34 pm
by dizzyd
Hey can i get that excel spreadsheet please?

Re: Pump Forces, and Pressures

Posted: Mon Nov 26, 2007 10:41 pm
by Silence
Just a reminder: note the dates of posts before replying. This thread is nearly a year old, and TheEngineer's public profile says he hasn't logged in since 01-22-2007. He left his email though, so you could try contacting him through that.