I have two fridge vacuum pumps / compressors and a LPG tank that will hold a vacuum
is that any good for a start.
Also ten air bags in stock waiting for ideas can have over fifty for the next BBB.
Sounds like a great start!
Anyone any ideas on the physics involved ... I'm guessing the limiting factor is the vacuum which can be pulled, but a longer tube would store a larger (or is it lesser) vacuum and power the projectile over a greater distance.
The projectile could be a sealed fit in the tube and contain a NRV to let the vacuum to the front.