Aircraft Carriers

[Spey_Phantom]

bump

revisiting this thread as to ask a question, as you know im nearly finishing a new 1/144 carrier, but i already have an idea to convert a couple of old hulls into small WW2 escort carriers, folowing the rerelease of revell 1/144 warbirds.

for research purposes, i bought a revell 1/720 scale Graf Zeppelin.
as i was looking for info, i found that the German Kriegsmarine was converting a cancelled Hipper-class cruiser, the Seydlitz, into an aircraft carrier.

but looking at the decks of the Seydlitz and the Graf Zeppelin, i noticed the germans have installed short catapults and i was thinking, arent those a bit short to launch such heavy aircraft like the Ju87 


http://en.wikipedia.org/wiki/German_cruiser_Seydlitz

[pyro-manic]

Wiki says the Ju87C (carrier version) was tested on catapults at 5300kg, and could be launched with 700kg of bombs (one 500kg and four 50kg). Sounds fairly reasonable to me. Swordfish were launched from RN battleship waist catapults, as were Ar196s from German cruisers. Neither is as heavy as a Stuka, but it's not far-fetched IMO.

http://en.wikipedia.org/wiki/Junkers_Ju_87#Ju_87C

[Sauragnmon]

Let's not forget that the Germans were the first to use Steam Catapults - the V1 was launched on a chemical-fuelled steam catapult using T-Stoff and Z-Stoff to generate the steam blast required.

[Spey_Phantom]

i see, but still i have one thing that doubts the carriers lauch capability.

while the british, japanese and american carriers had the aircraft take off, one by one, from the deck under they're own power, the Germans planned to lauch they're aircraft by pairs with the catapults. but these catapults were the same as they used on battleships/seaplane tenders to launch seaplanes, with the aircraft mounted on a collapsable cradle. i thinking, to launch those aircraft, it had to be very time consuming to mount them on the cradle first?

http://en.wikipedia.org/wiki/Graf_Zeppelin_class_aircraft_carrier#Catapults

[Sauragnmon]

Call me crazy, but I think that was the Original plan... and that was pre-war, so they might well have reconsidered the cradle launch tactic and gone for a different launch system.

[pyro-manic]

The wiki article covers it well, I think. The aircraft were to be fitted to the cradles by a crane in the hangar, and the complete assembly then raised to the flight deck for launch. No reason why you can't have a number of aircraft prepped and on the cradles waiting to go. Plus the operation to fit the cradle doesn't have to be very time-consuming - hook plane to crane, raise it up to the required height, slide the cradle in underneath, and lower it. Can't see that taking more than five minutes or so? How workable the actual concept is in action is another matter...

[NARSES2]

Would be fun in the North Sea or Atlantic during a mild blow as well

[McColm]

I know that there are kits out there that recreate the flight decks of aircraft carriers in 1/72 scale, but are there any kits that you can buy to make the superstructures?

[Old Wombat]

A simpler system would be similar to current catapults in that it would be mounted in the deck.
A hook would be fitted to the aircraft between the main wheels (maybe slightly aft) to which a bar or sling-cable would be attached. Cat block would be just aft of the prop when the aircraft is hooked up.
Aircraft would be launched wheels-down, hook-up time would be several seconds & the deck would be clear to allow "runway" style launches if required (ie: the cat has fouled & you need to launch your aircraft against an enemy battle group anyway... or be sunk).



Guy

[rickshaw]

Why not have a large, Y shaped shuttle, the arms of which can be extended out to the width of the aircraft's undercarriage?  You drive the aircraft up, the undercarriage engages the arms of the Y and the catapult pulls the aircraft into the air, via its undercarraige.  The aircraft can rotate and fly off the end when the shuttle stops at the bows.

[Old Wombat]

Damned good idea, Brian, but my argument against it would be 2-fold;

1) it's slightly more complex than a stick or string system & the Y-beam would have a tendency to require frequent replacement due to metal fatigue issues due to the backward flex during the initial stages of the launch & the forward flex as it hit the buffer at the end of the cat track, whereas the cat block is, quite literally a block & is not as severely effected by these forces; and

2) in addition to the regular additional weight of carrier operation modifications, it requires a much more modified, stronger & heavier undercarriage to take the forces required to launch a plane using this system, while the stick/string system requires only a few kilo's of steel hook.

[Thorvic]

I know that there are kits out there that recreate the flight decks of aircraft carriers in 1/72 scale, but are there any kits that you can buy to make the superstructures?

Nope, and the deck kits are either of a catapult or the angled deck landing area rather than the deck park around the Island. The trouble is islands are rather tall to model enough of a section to make it identifyable as a Carrier Island, it would end up over whelming whatever model was supposed to be the centre piece of the diorama.

However you can get 1/72 naval fixture and fitting for those who build the motorised boats for sailing on lakes & ponds. So you can get details such as watertight doors, lamps even weapons to replicate a section of Island.

[PR19_Kit]

2) in addition to the regular additional weight of carrier operation modifications, it requires a much more modified, stronger & heavier undercarriage to take the forces required to launch a plane using this system, while the stick/string system requires only a few kilo's of steel hook.

That's pretty much what the USN does today, isn't it? The cat shuttle tows the aircraft via the fold down arm attached to the nose leg.

[rickshaw]

Damned good idea, Brian, but my argument against it would be 2-fold;

1) it's slightly more complex than a stick or string system & the Y-beam would have a tendency to require frequent replacement due to metal fatigue issues due to the backward flex during the initial stages of the launch & the forward flex as it hit the buffer at the end of the cat track, whereas the cat block is, quite literally a block & is not as severely effected by these forces; and

2) in addition to the regular additional weight of carrier operation modifications, it requires a much more modified, stronger & heavier undercarriage to take the forces required to launch a plane using this system, while the stick/string system requires only a few kilo's of steel hook.

The undercarriage would already be required to accept the stresses of carriage operations, I doubt it would need to be strengthened further, particularly if acceleration was kept low in the initial stages of the run.   Doing that would also prevent the shuttle Y beam from being overstressed.  If you're worried about deceleration surely short run of track beyond the bows, looking rather like a Bridle Catcher where the beam was slowed would work.  You could then have a handling system which ran the beam back under the deck to the starting position.  Utilising several beams you could have a continuous chain of them.   Perhaps instead of steam you could use a flywheel arrangement with clutching and declutching?

[Old Wombat]

This is the current system used by modern tricycle undercarriage jets (taken from wikipedia).

Note how the launch bar & shock strut are in near-direct alignment. This is how the modern system works with minimal weight increase, the shock strut absorbs the force of the pull.

Older system used to launch the French Super Étendard

Uses under-wing hooks & a wire sling.

Same system used on an TBM Avenger.


A Grumman S2 Tracker (How'd that get in there? )


... and an illustration of an A4 Skyhawk (Hi, scooter! ) set to launch


You will note that only the modern nose-gear launch system used the undercarriage in any way, that is because it is the only one where the under carriage could be used without a massive weight increase to prevent it breaking. Even the Super Étendard's shock strut attaches too high on the nose wheel for it to use the launch-bar system.

But that's me, I'm a bit of a minimalist when it comes to technology & engineering - use the simplest, easiest system possible.