Supersonic ping pong ball

[BrainEater]

I seem remember a Mythbusters episode on a high powered
Air Canon shooting ping pong balls. But they only used Air.

Jerry

The Mythbusters ping pong cannon operates exactly like mine, Vacuum+pressure.
As far as I know, the Mythbusters hold the "air" record at Mach 1.4
------------

The equation for the 'exhaust velocity' of a C-D nozzle includes the variable "Universal Gas Constant".
Helium has a better gas constant.
Yes Hydrogen is even better, but as someone who has worked with hydrogen, it has safety issues.
This cannon is only supposed to go "bang" , once per shot !

 

[BrainEater]

I was thinking about if it could move heavier stuff, then saw this:

Heheh

Everyone asks about heavier stuff, I always say the same thing:
"making something heavy go really fast is easy, it's called a cannon. Want to go faster? thicker barrel more dynamite."

Making something really light go fast is hard, and where the art comes in.

-----

Space was mentioned above, here's a good example :
A 1/4" fleck of paint moving at orbital velocity (25-30,000 MPH) will make a really bad day for anything it hits.

 

[BrainEater]

Thanks for the moderation Unown (WILD) !

It's a science thread, no need for any shenanigan's over anything.
-----
While I'm mostly trying to get out to the mountains for some skiing, I am working on this.
-------------
I've taken the whole vacuum cannon apart, I'm redoing the C-D nozzle. The old nozzle has a throat of 7/8 inch, the maximum velocity I achieved with Helium was Mach 1.25.

I'm molding a new nozzle :



The new nozzle negative mold leaning on the old nozzle assembly. The new nozzle throat is 5/8", this should bump things up to Mach 2+.

Physics baby !
AKA Learning how to exploit the basic laws.

 

[BrainEater]

Normally, I'd be off chasing powder by now, but the snow in Western Canada sucks right now.
So I'm working on this.



New nozzle mold.
The old Mach 1.25 nozzle is on top of the molding material I use to make these nozzles.
----

--
You can see the back end of the negative rocket nozzle mold there....
--
The new nozzle is much smaller, under 5/8", I expect Mach 2+.
I'm purchasing new molding compund tomorrow I hope....