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Thanks iX Cameras [ Ссылка ] and Matt Rece [ Ссылка ] for helping with the high speed shots!

Giaco Whatever video: [ Ссылка ]


A few more thoughts on the Nerf Cannon.
Yes, I know if I used a longer barrel I could get higher speeds, but I did not want to deal with a 20ft long gun. I think a 6ft barrel was enough to show what a supersonic nerf dart can do.

Davekni got a pingpong ball going 2000mph which is 2930 ft/s!! (mach 2.5). His barrel was 20ft long. It can shoot through 3/4in plywood! You can see that video here- [ Ссылка ]

I always thought the speed of sound was the limiting factor, because the flow 'chokes' at mach 1. Its a big controversy among air-gunners, and theres like a 900 post topic on it here [ Ссылка ]. Some guy got one going like 2100 ft/s which I thought was impossible. [ Ссылка ] So it prompted me to do some research.

It turns out flow does choke at mach 1, but its only the mass flow that chokes. The gas can still expand supersonically.



Also a big thanks to Dr. Carl Knowlen from University of Washington, and u/Overunderrated, u/TheQueq, and u/InductorMan from reddit.





Here are the papers I referenced:

A COMPARISON OF DISTRIBUTED INJECTION
HYPERVELOCITY ACCELERATORS - [ Ссылка ]
Probably the most concise and easily understood!


Numerical Evaluation of a Light-Gas Gun Facility for Impact Test
[ Ссылка ]
Shows different muzzle velocities for different barrel lengths


THE THEORY OF HIGH SPEED GUNS
[ Ссылка ]
Probably the most extensive on the subject "The reader Is assumed to be an advanced student in engineering." I hope you payed better attention in physics that I did.

Outro music by MDK, [ Ссылка ]

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