How do you get a 45,000 pound plane up to launch speed on a 270-foot aircraft carrier runway? With a giant, steam-powered catapult of course. Jörg Sprave would be so proud.
The modern aircraft catapult, part of the CATOBAR (Catapult Assisted Take Off But Arrested Recovery) system, consists of a towbar, which attaches to the landing gear under the plane's nose, connected to a shuttle. The shuttle then connects to a metal lug that pokes up through a slit in the deck and is itself attached to a pair of below-deck pistons. These pistons sit in parallel cylinders, 18-inch diameter and about 100 yards long, which are "charged" with high-pressure steam from the carrier's reactors.
Once the cylinders are sufficiently charged—too little pressure and the plane takes a dip in the ocean, too much pressure and the shuttle will rip the front end of the plane off—the aircraft opens up its throttle (for added thrust) and the catapult officer releases a lock on the pistons. This causes the pistons to slam forward, accelerating the plane down the runway and off the end of the carrier—going from 0 to 165 MPH in two seconds.
To keep the shuttle from simply careening into the end of its track (or clear into the ocean) at 165 MPH, carriers employ a water brake system to slow it down with out damage. This consists of a horizontal dashpot filled with aerated seawater. The resistance this water provides slows and eventually stops the charging pistons. [Wikipedia - US Navy Aircraft History - How Stuff Works - Electronic Aviation]
Monster Machines is all about the most exceptional machines in the world, from massive gadgets of destruction to tiny machines of precision, and everything in between.