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Subject: Alternative CATAOBAR Carrier Concepts
VGNTMH    7/31/2007 2:56:40 AM
I have been thinking about CATOBAR carriers recently and have come up with two slightly weird ideas! ***** Two Flight Decks ***** In modern CATAOBAR carriers: • 100% of the launches are via catapult (excluding helicopters but including COD and Hawkeyes etc) • 100% of recoveries are via arrestor wires • The catapults are quite long, at least 60m, more usually 70 to 90m long, and allowing for space to set an aircraft on the catapult the total length required approaches 100m • The length of angled flight deck required for an arrested recovery is quite short, the aircraft either catches an arrestor wire and stops or misses and goes around again • It is desirable to allow for simultaneous catapult launches and arrested recoveries All correct so far? Why not design a CATAOBAR carrier along the following lines: • Have two flight decks, the upper one with the arrestor wires the lower with forward facing catapults. • The flight decks could both be straight, that is there is no need for an angled deck, if an aircraft misses the arrestor wires on the upper flight deck, it still has a clear path and can still go around again • The catapults on the lower deck could be as long as required, even 100-120m, as they could go back into the lower deck hanger • The upper flight deck could be only about 150m long on a approx 250m ship, meaning that the catapult section of the lower/hanger deck could be substantially in the open • To allow for sufficient freeboard forward, the upper flight deck would need to be quite high, posing possible stability problems, but these would be reduced by the fact that the heavy catapults would not be on that deck, and because the upper flight deck might only be 60-75% of the length of the ship, and because there would be no need for an angled deck • Overhanging parking sponsons/areas on the upper flight deck could still be used for parking recovered aircraft and for operating helicopters • Deck edge lifts, presumably two, presumably located towards the forward end of the upper flight deck, would be used to move recovered aircraft to the hanger/catapult deck for rearming and launching The end result would be a bit analogous to (the second incarnation of) HMS Furious in the 1920s! Is there any merit in such a CATAOBAR carrier? I figure that the pros of this idea could be: • Smaller CATAOBAR carriers might be possible, given the long catapult lengths, in relation to the ship, which can be facilitated • A higher tempo of operations might be possible, compared to a similar sized single flight deck angled deck CATOBAR carrier with interference between the catapults and the angled deck, due to the separation of launching and landing aircraft And remember that the wingspan of even an F/A-18E sized aircraft (approx 14m) is narrower than even an HMS Invincible sized hanger (approx 30m). So having the catapults going back into the hanger would not be impossible. Though the hanger sides would need to be open to allow for the deflection of the jet exhausts! And perhaps the two catapults would need to be staggered slightly. I know that the twin flying off deck carriers of the 1920s (Furious, Courageous, Glorious, Akagi, and Kaga, all before being rebuilt) and the hanger deck catapult carriers of the 1930s (I think limited to Yorktown CV-5 and Enterprise CV-6 and possibly Hornet CV-8) were not successful! But the lower flying off deck didn’t work due to heavier aircraft exceeding the short forward take off distance available without a catapult. And both of these were in the days before every aircraft had to be launched via catapult. And an even more revolutionary addition to this concept would be to do away with most lifts and have a ramp descending from the upper deck to the lower deck. A ramp might be more realistic than it currently is as only returning un fueled and unarmed aircraft would be descending from the upper flight deck to the lower hanger and catapult deck and because there is no need to move aircraft up! Except for perhaps helicopters. ***** “Bullpup” Carriers ***** Alternatively, if the above is either impractical or impossible, why not: • Stick with a single flight deck with an angled deck • Move the angled deck forward to the middle of the ship, or even further forward • Have long 100m catapults on the flight deck, crossing the angled landing deck, with the catapult assembly and loading area to the stern of the angled deck • Possibly, and this would be revolutionary, move the island to the rear port quarter Sure 100% simultaneous launches and recoveries would not be possible, as the catapult tracks and angled deck would intersect, but aircraft could still be setup on the catapult ready for launching while other aircraft are landing. And such an arrangement would allow for smaller CATOBAR carriers as current CATOBAR carriers are partly limited by the length of the catapults. Correct? We could call such an arrangement a “bullpup CAT
 
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VGNTMH       7/31/2007 3:09:38 AM
Oops ... at least one silly thing ...
 
All mentions of CATAOBAR should be CATOBAR!
 
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french stratege       8/3/2007 7:31:43 AM
I have thought to the same concept years ago .The problem you point out is clearly stability issues due to landing deck.The catapult deck must be high enough to be safe from big waves and also to allow a minimum height from the sea at plane exit.
I though also that you could put a jump on take off deck.After catapults or for a STOBAR carrier.
AN advantage could be to make a reduced RCS carrier.
 
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Herald1234    Why don't both of you   8/3/2007 9:41:43 AM
try looking at plane parking and movement on aircraft carriers, how bombs and missiles are moved around on those ships, how  the planes are actually refueled , and and how launch recovery cycles ACTUALLY work?

You'll quickly discover WHY the  British  found the double hanger was a disaster and why the angled  deck  STOBAR and CATOBAR  flight deck geometries, the simplest  and SAFEST operating  geometries, they adopted for conventional aircraft..

Herald

 
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ShinyTop       8/5/2007 10:42:15 AM
Dont' forget about hanger and deck space.  As it stand on our big super carriers we still have a permament deck park, we can't store it all in the hanger deck.  So if we make the landing deck smaller we lose that space and we lose space in the hanger by setting aside space for catapults.  I believe the deciding facotr in the size of the carrier is the optimum air wing size and that requires storage space.
 
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