Fun with ice.

[tazman]

Check your arithmetic!

A bullet at 1000 FPS, in a 1 in 12 twist, spins at 1000 FPS, or 60000 rpm.


Sent from my iPhone using Tapatalk Pro

You are correct. I forgot to do the last step of the equation. It should have been 88,000. I will correct the first post.

[dogmower]

I don't believe the bullet is spinning that fast. If it could fly for a full minute it would rotate a total of 1400 times

actually, even with the corrected value of 88,000 rpm, that value isn't too high. high speed medical and dental drills run at those speeds all the time, for hours on end, whereas a bullet RARELY has a full minute time of flight, and that would NEVER be a 9mm handgun.

[Messy bear]

Wish I had pix. Maybe get some done sometime. They look like they come out of water if impact veocity isn't too much for alloy.

[leebuilder]

Only two pristine ones, the rest hit wood.
Hope to find more next thaw.
Be well

[leebuilder]

Pays to look up

[45workhorse]

Reload that blue one. The one stuck in the tree,again!!!!!

[David2011]

I don't believe the bullet is spinning that fast. If it could fly for a full minute it would rotate a total of 1400 times...over it's entire flight...it only turns once every 9 inches....so...for example if it hits a person...it would only rotate once from front to back if a person was 9" thick.

redhawk

The bullet is only turning 1:9 as it leaves the barrel. As the velocity drops the rpm remains pretty much the same so when the velocity had dropped in half the bullet will be turning close to 1:4.5. (Crude example)

The rpm figure is like a snapshot for the moment.
It would make one turn in the 9 inches, but it also covers that distance very quickly.

Here's something kind of cool:
Another 'do the math' exercise that comes out with a interesting number is--- if a dragster's engine is turning 10,000 rpm--
on a 1/4 mile run it covers in 10 seconds, the crankshaft may only actually rotate a little less than 1000 or so times.

A top fuel dragster will cover the 1000 feet (no longer 1/4 mile for top fuel and funny cars) in about 3.8 seconds and average around 8000 rpm so they only turn about 500 revolutions not accounting for the time the clutch is slipping prior to lockup. That 500 revolutions costs somewhere around $6000.00 in tire wear, an engine rebuild, 18 gallons of nitromethane and labor costs.

[Nazgul]

Frozen trees, oh my!! In my misspent youth, I fired a .69 cal flintlock pistol at a target on a frozen oak tree. That ball came straight back between the eyes. My head is hard, no real damage but wow, what a headache for a week. That and explaining to your parents how you did it.….……………….

Don

[West Creek]

Friend of mine was walking the woods with his kids. The kid shot at a frozen oak tree 40 yards out and the bullet came back and hit him in the zipper. They picked the bullet up off the crusted snow they were walking on. Yep don’t shoot trees in the winter, they make bad back stops.