The feasibility of compressed air catapults.

Ming777

Monthly Donor
The German aircraft carriers Graf Zeppelin was intended to launch aircraft using compressed air catapults. It was concluded that given the design intended to be used, it would take 50 minutes for the air reservoirs to recharge after launching an attack wave.

My question is this: is it possible to make a compressed air catapult to launch jet aircraft that doesn't take as long as Graf Zeppelin would have had to recharge the air reservoirs. It could be used on ships that don't generate steam, like gas turbine and/or diesel powered warships.

I'm thinking a modern design might include elements similar to those used in air actuated systems, like that used in the air brakes of commercial trucks and trains. In these systems, compressed air is stored in a series of reservoir tanks, before being fed to the individual braking systems.

My idea is that the catapult system would use two or more reservoirs, with one reservoir being fed directly by a compressor, while a regulator would transfer compressed air to the second reservoir. Thus, while the catapult is in use, the compressor can continue to operate, filling the first reservoir which feeds air to the second once the second reservoir's pressure goes below a certain threshold.
 
Doesn't solve the problem - what you really need is a bigger air compressor, rather than more individual reservoirs. Doubling the capacity for the same compressor means you can launch twice as many aircraft before you have to recharge, but then the recharging takes twice as long.
On a single reservoir system you'd only even consider valving off the compressor from the reservoir for the few seconds the catapult is in use (and probably not even then, if the reservoir is big enough). What you're suggesting adds a lot of weight for very little practical benefit.
 
GZ had enough air capacity to launch all the Stukas and 109Ts before recharging.

doubtful that all could launch, do the strike, then return and rearm quick enough that they would have to wait for the tanks to pump up before launching again.
 

Saphroneth

Banned
GZ had enough air capacity to launch all the Stukas and 109Ts before recharging.

doubtful that all could launch, do the strike, then return and rearm quick enough that they would have to wait for the tanks to pump up before launching again.
Did she really? I've heard that "attack wave" means about half of them, that's how most carriers had to launch their flock. (Midway the Japanese carriers launched half-strikes from each deck, the US carriers had to launch half and have them orbit while they readied the other half.)
 
There is a difference between having enough air in your resevoirs to lauch all your aircraft and the deck space to range the strike. Allied and Japanese aircraft carriers had biggers airgroups than they could range on deck for a single launch. So this became the limiting factor. There is a ponit where so much deck is occupied by ranged aircraft you have no space for a take off run and catapault launches become the only way. This is slower than free launching so normaly as soon as sufficent space had been cleered the rest of the group would free launch.
 
The Malta class could bring running, warmed-up aircraft directly from the hangar deck on their deck-edge for immediate free launch. IIRC the Malta was designed to launch 80% of its CAG in a single strike. I would not be surprised if the Essex and Midway classes got similar advantages from their open hangar and deck edge lifts.
 

Saphroneth

Banned
Catapults are also required for off-axis launches, I believe? (that is, where you're - say - steaming across the wind, and you don't have the chance to go to steaming into the wind.)
 
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