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Registered Member #1329
Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53
Hello Folks, I am curious what the fastest projectile speed any one has recorded for a coil gun built by an amateur or group. For example not the military. Using the projectile drop over distance method, I was able to measure consistantly between 80 to 85 Fps with my single stage 25 gram projectile.
I don't know if this is good or bad, but this is my starting point. Has anyone every acheived 500 FPS or greater? PauLC W1VLF
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
I was able to measure consistantly between 80 to 85 Fps with my single stage 25 gram projectile.
I don't know if this is good or bad, but this is my starting point.
The most important measure for coil guns is the efficiency. How much energy ended up as kinetic energy in the projectile compared to what what was in the capacitors to start with.
As the projectile goes faster it becomes more difficult to keep the efficiency high.
The fastest speeds (maybe out of date) are recorded on the forum somewhere but as usual they are impossible to find. If someone finds them then stick them in the wiki.
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
I'm not up to date on recent results, but I achieved just shy of 100m/s with a 14 gram slug using a six stage (extremely inefficient) 4.7KJ coilgun back in high school.
Had I known then what I know now I'm fairly certain I could have easily surpassed 150m/s (which equates to a respectable 5% efficiency)
There have been a few claims of >200m/s with a reluctance gun, but I don't really know how reliable that is.
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
There are a number of old threads about it in the archives.
It was a 6 stage, 4.7KJ SCR switched coilgun. All stages were symmetrical, and were made up of 350v 3700uF general purpose electrolytic capacitors.
The projectile was 1/4" diameter, 2" long and weighed between 10 and 15g depending on which projectile I was shooting.
The barrel was made out of .375" OD, .25" ID delrin tube machined down to .3" OD at the coils.
It was optically triggered, and switched with a large bank of 6 phase control SCRs.
It was a pretty simplistic design overall, which likely contributed to its inefficiency.
EDIT: I found the old thread in the archives. Keep in mind I didn't know half what I do now about coilguns. Quite a bit of the stuff I stated as fact in that thread is wrong in one way or another.
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What is the fastest projectile speed have you seen from an amateur coil gun.
