Home Forums Hunting & Shooting Ask The Gunwriters Breaking the sound barrier (in solids)

The spped of sound in a solid is roughly 5400 fps. How would a bullet impacting an object above the speed of sound in a solid react? Would it explode due to the high velocity? Or would it penetrate like nobody's business because it wouldn't realize that it hit anything? Has this ever been tested?

I'd imagine necking a 6mm Remington to .14 would send really light frangible bullets just above that barrier and provide a good test platform. And after shooting it out, you could have it rebored to .17 or .22. But I'm just really curious about this though....

Not to question your post, but, the speed of sound is actually much slower. It is 1129 fps at sea level for the most part. Even 22 LR bullets exceed the speed of sound, usually.

The speed of sound in dry air varies with the temperature of the air � from 264.66 m/s at -99� C to 370.96 m/s at 69� C.

(It's late, and I'm bushed, so I'll let you do the conversions to feet per second and degrees Fahrenheit! )

The speed of sound in a solid is higher than that in air.
I'm not sure where the 5400 fps came from.
Energy will travel through a solid at the speed of sound.
Good luck!

From working with sonar many years ago, I seem to recall that speed of sound in water is approximately 5000 fps. Should be a good approximation for flesh.

Speed of sound in steel is in the range of 15K - 20K. Speed of "kinetic energy" round from Abrams tank is only approximately 5K. It penetrates steel and does make a mess inside another tank, even if it is subsonic in steel.

I suspect that any conventional bullet hitting flesh at over 5K would make a big splat without having super penetration. The Abrams does have the advantage of a heavy "long-rod" penetrator.

Ken O

Do some internet research on "light gas guns."

A start:
http://en.wikipedia.org/wiki/Light_gas_gun

The article mentions speeds up to 7 kilometers per second (about 23,000 FPS)

Bruce

I remember reading, many years ago of some testing done at MIT.

They made some type of gun that shot a projectile at about 8000 FPS. The reason for the test was to determine the amount of damage a space craft would sustain from being hit with high speed particles.

IIRC, the projectle did penetrate the simulated surface of the space craft.

Most of the stuff posted here is incorrect. I formerly worked at a company which designed missiles used to penetrate armor--tanks, bunkers, and the like. Though my field was guidance and control, I knew how the warheads worked.

When an impact occurs at a speed faster than the speed of sound in either (a) the projectile or (b) the target, this is known as "hypersonic velocity." The physics of the impact is the same as liquid impacting liquid. Penetration is A LOT more than anything below hypersonic.

It is (probably) impossible to launch a practical projectile at this speed. Instead, a "shaped charge" is used. This consists, usually, of a thin aluminum cone, flying base forward, with explosive behind it. Upon impact, the explosive pushes the point forward and turns the cone inside out. As this happens, the part of the inverted cone being pushed forward pushes and accelerates the rest of the cone. The aluminum ends up at hypersonic speed. The velocity of the projectile itself at impact does not matter.

If you are inside a tank hit by even a relatively small missile with a shaped charge, many inches of armor plate will not protect you. Molten metal droplets fly around inside the tank at hypersonic velocity. Everything dies. The fuel bursts into flame. And the munitions explode.

The shaped charge principle was first worked out during WWII by Dr. Emerson M. Pugh, a former professor of mine. It was first used in the bazooka, which allowed a relatively small projectile traveling several hundred feet per second to destroy a tank.

This principle has no hunting application. During the 1991 Gulf War, however, I heard that Saddam was piling sand up around his tanks to protect them, leaving only the turrets sticking out. Sort of an instant pillbox. From what I knew of even the obsolete ca. 1968 versions of our missiles, I was amazed at this. For if an F16 pilot sees such a target, the target will die. The tank crew will have no advance notice. The F16 will remain perfectly safe.

This is off topic but as I remember the Russian tanks couldn't be moved very much due to their bad transmissions.
Good Luck!

I suspect one ends up with molten and ionized metal. Likely the toughest part is constructing a projectile that would not ionize in flight and briefly hold together on impact.

I don't know that it's correct but an avionics fellow once told me that during flight a shift from sub to super sonic is similar to shifting from air type controls to components that act more like they are functioning in water.

Solids don't tend to flow out of the way like gases or liquids.