Hi Kids! Ever wonder how Santa can get presents to all of the good little boys and girls in only one Christmas night? Well he’s been able to do it so far through his super-sonic X-treem X-mas sleigh, but I have recently discovered research released by Kringle Development Laboratory’s North Pole facility that shows recent advancements in present delivery systems.
Instead of having Santa visit every single house, presents could be delivered with precision by launching them from the north pole with a rail-gun projectile platform. Here is the video of the recent results (shared with the Navy), where a 23 lb metal slug was launched at 7 times the speed of sound from the muzzle of a 32 Megajoule railgun.
Here’s the video of the test launch:
Here is a bonus video in extra slow motion.
More explanation below…
What is a Railgun?
A railgun is an interesting type of weapon because unlike conventional weaponry it does not use any type of explosive material like gunpowder as a propellant. Instead it uses nothing but electricity to create perfectly timed magnetic fields that accelerate a metallic bullet up to ridiculous speeds.
How does that work?
Basically there are two conductive rails on either side of the bullet. When current is applied to the rails a circular magnetic field is formed around each rail, such that inbetween the rails the magnetic field is extremely high (see picture). Current also pases through the bullet, and the current in the bullet interacts with the magnetic field created by the rails to produce what is called the Lorentz force, which drives the bullet along the rails.
The Lorentz force has the form:
There are a few terms in here but the take away message is that the force (F) applied to the projectile is proportional to the magnetic field (B). So to increase the final velocity of the bullet, one just has to ramp up the strength of the magnetic field.
No explosives eh? Why do I see an explosion following the bullet? Why do I hear a bang?
Ah you are referring to this:
One of the main issues implementing railguns is that the extreme amounts of energy needed to provide the force necessary to launch the bullet creates extreme temperatures. The temperature of the bullet as it leaves the gun is so high that it rips the electrons off of the gas in the air and creates a plume of super-heated plasma behind it. Awesome! The bang you hear in the video is also of course the sonic boom caused by the projectile breaking the speed of sound. Super!
I thought this was Explosion Friday?
Ok so I cheated a little bit, it’s not technically an explosion. But it is super cool and I hope you enjoyed it anyways!