battleship catapult procedure?

[synthesim]

I wonder if someone can please tell me exactly what goes on when an aircraft is catapulted from the ramp of a battleship?
In 'Shattered Sword', they say it is a dangerous procedure that uses 'explosives', but give no details.
Do they actually use rockets to fire the cradle down the launch rails?
Or how does it all work, please? Thank you to anyone who can help.
I would appreciate any details at all, no matter how few. Thank you.

[frontkampfer]

My father served on the USS Missouri and I believe he said the US Navy used a 5in charge to fire off the float planes. The Germans used compressed air and that was did in the Bismarck's float planes when they tried to fly off the Log Book. A shell splinter from PW cut the line an prevented the launch. Maybe if they had used an "explosive charge" it might have made a difference. Hope it helps!

[synthesim]

Thank you very much. This is getting increasingly interesting.

Okay, I found out that in the case of WWII Japanese catapults, a small black powder charge is exploded inside a steel container, which buffers the shock of the explosion and releases the explosive gas in a controlled way into a cylinder, where its drives a piston. The connecting rod of the piston than drives a system of cables and pulleys to move a cradle down the length of the catapult. The plane to be launched rests in the cradle.
Sounds like a reverse pulley system, where you pull the multiple pulleys apart and the end cable gets whip-snapped down the catapult ramp at high speed.

You say a 5 inch charge (like a 'blank' in a pistol, I'm assuming) was used for American WWII catapult launches?
Possibly similar to the Japanese system, but with a 5 inch 'blank' shell?

[synthesim]

PS - my sincere respects to your father.^^

[frontkampfer]

Yep, it was a blank charge. My dad said he would watch the launch & recovery of the float planes if he could.

[Rick Rather]

Earlier US BBs may have used the black powder method. IIRC, USS Arizona kept its black powder charges in a small compartment above the main battery's forward magazine. It is believed that the bomb that hit forward ignited the black powder charges, and this threw flaming debris into an open hatch on the main magazine, setting it off and destroying the ship.

I wonder why they kept the black powder charges forward, when the catapults were both aft?

[CPL Punishment]

Yep, it was a blank charge. My dad said he would watch the launch & recovery of the float planes if he could.

It wasn't necessary to use a "blank" charge. The 5"/38 DP gun, which was a standard weapon on virtually every class of USN warship, fired a two-piece round: a 55lb projectile, or "shell", and a separate propellant unit generally called a powder case. The big naval rifles like the 16"/45 guns of the SoDaks and the North Carolinas used powder cases made of silk, four or five of them loaded behind the projectile. The powder case of the 5"/38 (aka Cartridge Case Mark 5) was a brass cylinder filled with cordite and having a black powder percussion primer at the breech end and a cork plug at the other. The reason for this arrangement was to make make the ammunition easily manhandled, because a self-contained round like a tank round would have been too long and heavy for the average gunner to pick up and load. In short all the 5" charges were "blanks", and any standard 5" charge would do to operate the aircraft catapult.

Here's a graphic that shows this in detail:


Here's a pic of spent power cases strewn across the foc'sle of USS Hobson after her fire support mission off UTAH beach

[tommy303]

The system is known as a high/low pressure principle in which a stout firing chamber contains the burning gases of the powder charge while a venturi system allows the gases to blead off into a lower pressure piston chamber. A similar method was often used for torpedo launching from surface ships.

[tommy303]

Here's a link to the proceedure:

http://www.navsource.org/archives/01/57l.htm