Discussing future and (im)possible carrier technology

Delft, popeye and me had a really interesting discussion about possible aircraft carrier technologies and designs and I'm curious about other's input.

Landing and take off:
Delft and me are fans of the ski jump ramp, but have to acknowledge that popeye is right in so far that aircrafts can't start with the same load from this device as from a normal steam catapult. The know-how of operating steam catapults seems to be rather limited to the US (who give the French a helping hand).
We speculated about a catapult for ski jump ramps that could help reduce the energy requirement of aircrafts otherwise using their afterburner for take off. But popeye is right that this doesn't solve the immense frontal landing gear stress that limits the load. I consider it possible that something light and with as much wing surface as a Gripen might serve fine, but I don't know.
It's really quite rude how these aircrafts are handled on a carrier.
In the end I'm a fan of the Russian STOBAR design because it solved the problem with the least technical complexity, but as seems a habit for Germans, I'd like to improve the technology. One of the reasons why I favour ski jump ramps even in combination with arrested recovery is that you need only half the speed to take off from suich a ramp, so the reduced speed means 4 times reduced stress on the airframe and a much more relaxed pilot at lower speeds with better chances for arrested recovery. The aforementioned problems of reduced take off weight, capability, range and endurance remain, so the Russian(Soviet) STOBAR doesn't compare well in aircraft performance to the US CATOBAR systems. Can the gap be narrowed?

Carrier design
Most will be familiar with the US carrier designs that in my opinion derived from fast cruiser hulls.
I consider a different approach feasible that is a mix between a SWATH in the Sea Fighter (FSF-1 style and the Juan Carlos I (L61) (and Canberra-class if they turn out carriers in the end) and would develop something similar to the new LHA. You can build one rectangular crosscut hull, used in riverine shipping for example, and flood the waterline compartements. In the floating compartements underneath you could store fuel, gas on the sides and oil in the center. Many conventional ships use oil in diesel engines for cruising and gas turbines for high speed.
While such a design inherits stable platform capabilities from the SWATH designs at reduced costs, and has great deckspace, it must become quite long because of the bow wave. An idea to reduce the bow wave of a broad naval vessel is the M-shaped hull, best known from the M 80 Stiletto. This design deletes the bow wave by mutual interference and poses high demands in precision engineering while also reducing list through a dynamic lift effect by the deleted bow wave.
Reducing the list due to sea state could offer a tactical advantage under conditions when or where one carrier can't launch the airwing and the other can.

Propulsion and energy storage
My idea would be to add a flywheel in a gymbal lock for storing energy from landing aircrafts and having a device for rapid energy transmission to accelerate the turbines and power other systems as required. The very heavy diesel engines would contribute part of the encasing armour such a flywheel system needs.
The other new tech favoured by Delft are superconductors for storing energy for and from electromagnetic linear accelerators on deck. The energy stored will likely be not enough to power up the turbines for example and it would need a direct transmission.
I consider storage of rapidly releaseable energy not only important for running up turbines, but also for high intensity electronic warfare. Jamming a frequency hopping device requires lots of energy for example.
Considering nuclear reactors, I'm well aware of the reliable US Navy handling, but with any nuclear reactor fiddling with energy output is dangerous, they better run on a constant state. The Russian had for example the brilliant idea to use a reactor for cruising and turbines for speed bursts.

I don't know much about ship propulsion however I do know what works. I'm no engineer. Not even close.

USN CVN Nuclear powerplants work The old USN steam turbines powered by boilers worked.

To launch aircraft... catapults work. Ski ramps work but limit the payloads of heavier aircraft.

I'm sure that someday the newer technologies will be put to use. but here in the present the tried and true methods shall remain in place.

How and how fast do nuclear carriers increase the energy supply to the ship and her systems? Or do they never shut down and rather emit the energy as heated water if not required?

Kurt said:

How and how fast do nuclear carriers increase the energy supply to the ship and her systems? Or do they never shut down and rather emit the energy as heated water if not required?

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They never shut down once deployed. Never.

example. The Nimitz was in the shipyard in Bremerton WA until June or July of 1989. Once she was under her own power the reactors stayed on line until the ship returned to the shipyard in Bremerton for a minor re-fit late in '91..nothing, to my knowledge as far as the USN use of CVN powerplants, has changed.

Thanks, that most certainly explains the high safety of these reactors because changing their energy or even shutting them down is a security problem.

bd popeye said:

I don't know much about ship propulsion however I do know what works. I'm no engineer. Not even close.

USN CVN Nuclear powerplants work The old USN steam turbines powered by boilers worked.

To launch aircraft... catapults work. Ski ramps work but limit the payloads of heavier aircraft.

I'm sure that someday the newer technologies will be put to use. but here in the present the tried and true methods shall remain in place.

Click to expand...

Aircraft launch - the modern, safest, and most efficient system will be EMALS. The US has already made hundreds of test launches on land and has already (as of late 2010) begun building this new system into its new class of carriers, the Gerald R. Ford Class, the first of which should see its major structural build close to being complete in 2012.

As to propulsion, the US has shown, over decades, that the best way is nuclear for these large carriers. heck, the first carrier to be powered by nuclear reacotrs, the USS Enterprise is still commissioned and on active duty after over fifty years of service. The newer reactors on the Nimitz class were much more efficient and have been powering these carriers the whole time since...with improvements as they went. Now, the new reactors on the Ford class provide over 200% more power than the Nimitz class in a smaller footprint and are much more efficient. That's where the power for emals is coming from, for the integrated network and propuslion system, and enough left over for future laser and dierect energy beam CIWS already under development.

One reactor on a super carrier is sufficient for its needs, the second is redundancy.

As to carrier design, the US has been working on and perfecting the design for its needs for almost 100 years. The latest carriers will have three elevators, a smaller, single island with all sensors integrated which is further back on the deck, and will be more efficient in sortie rate and aircraft handling as a result.

Other nations, with varying and not so robust needs, design them differently, but the US designs them for maximum speed, manueverability, sound dampining, and for the complex and major operations the US performs with these vessels.

As I say, other designs are optimised for other needs, be they multi-purpose vessels that combine aircraft ops with amphibious ops, or striclty for sea control as opposed to full strike at sea and on land capabilities, etc. Generally, those other designs are not as fast, as manueverable, and cannot support the sortie rate and tempo of operations the US carriers do...because they simply do not see the need for it.

As I say, other designs are optimised for other needs, be they multi-purpose vessels that combine aircraft ops with amphibious ops, or striclty for sea control as opposed to full strike at sea and on land capabilities, etc. Generally, those other designs are not as fast, as manueverable, and cannot support the sortie rate and tempo of operations the US carriers do...because they simply do not see the need for it.

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Also USN has a multiple of sea days and war days on their CVs of several kinds over the last ninety years than the sum for all other navies of the world together. To achieve anything worthwhile in the way of aircraft carriers a country will have to develop a precise model of what it needs and to look around for technologies to develop to realize that at an acceptable price . Trying to imitate what USN is doing will only result in massive waste. Think of CdG.
As for Kurt's ideas: I very much doubt that M80 can be scaled up to a reasonable sized aircraft carrier and if it can it would take more than thirty years. Ships with flooded waterline compartments will have a greatly increased drag and thus power requirement.
A Thorium Molten Salt Reactor might take fifteen years to develop and would need considerable less lead shielding. A valuable reduction in weight. By using one, very reliable, reactor and gas turbines for get home power if the reactor never the less fails you can have a further reduction in weight and costs. Then using the tricat ship shape you might have a relatively small carrier with a large flight deck reducing the amount of respotting necessary.
I think we are in for a fascinating period of naval ship development over the next quarter of a century.

what's on my mind for now, an all STOVL/VTOL 100k tonnes aircraft carrier, nuclear powered

multiple take offs and landings (in group of 6 or 12), no need for arresting gear and take off aid mechanism or long take-off/landing strip, maximum space management

CAG fighter ala F-35B, or something else
AEW and transport ala V-22
UAV complement
mini UAV cold launched from silos, ala the recent submarine launched switchblades
stealthy hull shaping and island shaping

also robotic ammo and fuel handlers, advanced AI flight and ops management, crew of hundreds instead of thousands
okay i guess i need to stop here, before mentioning the laser CIWS

delft said:

Also USN has a multiple of sea days and war days on their CVs of several kinds over the last ninety years than the sum for all other navies of the world together. To achieve anything worthwhile in the way of aircraft carriers a country will have to develop a precise model of what it needs and to look around for technologies to develop to realize that at an acceptable price . Trying to imitate what USN is doing will only result in massive waste. Think of CdG.
As for Kurt's ideas: I very much doubt that M80 can be scaled up to a reasonable sized aircraft carrier and if it can it would take more than thirty years. Ships with flooded waterline compartments will have a greatly increased drag and thus power requirement.
A Thorium Molten Salt Reactor might take fifteen years to develop and would need considerable less lead shielding. A valuable reduction in weight. By using one, very reliable, reactor and gas turbines for get home power if the reactor never the less fails you can have a further reduction in weight and costs. Then using the tricat ship shape you might have a relatively small carrier with a large flight deck reducing the amount of respotting necessary.
I think we are in for a fascinating period of naval ship development over the next quarter of a century.

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True, nuclear power is the way to go if you want as much operational experience as the US Navy with carriers. I consider your idea of combining nuclear power and gas turbines as even feasible if you use only one reactor and gas turbines for back-up. This would be a very light and cheap solution to the not inexpensive nuclear energy problem.
Considering the greatly increased drag of flooded hulls, I agree. The Mistral class is in my opinion a prime example for that, but this flooding also increases resilence against damage and list.
On the positive side such flooded compartments at the waterline reduce drag due to much reduced role and because it has catamaran stability with floats at the sides underneath, so it doesn't need as much ballast. All in all, I rather estimate such a design to need less energy due to less kinetic displacement if you make it long enough, Juan Carlos I (L 61)-style or future Canberra-class.
The M-shaped hull idea was for rather short and broad versions with more parking deck because the sleek long stable platform is more suitable for operating a commando carrier. I totally agree that developing a large M-shaped hull will be demanding (I mentioned the engineering problems).

Concerning take off and landing, I analyzed the problem and had a possible insight. You don't see E-2 Hawkeyes on ski jump ramps, rather helicopters take over this task for carriers with ramps, nor do you see the C-2 Greyhound.
Now back to my pet, a ski jump ramp with catapults. The problem with heavy aircrafts is the stress on the front landing gear. So I thought about solutions:
Make the front landing gear more elastic to absorb shocks to the airframe.
Add a catapult (needs to supply only 25% of the energy CATOBAR catapults do) and free (!) the aircraft engines for extreme thust vectoring in order to lift the aircraft's nose in time to make a maneuver like going for Pugachev's Cobra (but not doing it because this would indeed be futile). As a result of a lift in time there's not so much shock for specific parts at the ramp because the aircraft distributes the stess due to altered movement path on more parts of the airframe (might need a computer for realization). If you look at CATOBAR take off, the aircraft climbs some time after leaving the catapult, the difference of my idea would be to add this climb very shortly after leaving the catapult on a ramp. The CATOBAR concept has the advantage of a less time critical coordination with more leeway for error (but getting quite close to the waves for some pilots) and for accelerating still larger aircrafts with more load. Furthermore if you can build and need to maintain a catapult, why not make it 4 times stronger? So what I suggest would be a very high tech solution for someone who deliberately wants to keep his carrier small, but has all the know-how to make it larger (only a European can invent such a thing ). I would call it CASTOBAR and even a CASTOVL version might be feasible.

Aircraft carrier development could be seen also from a rather different angle. Why not build an early WWII aircraft carrier with a wooden flight deck? It would be very suitable for operating close air support aircrafts and helicopters, so it's a commando carrier today, ok. Why wood? wasn't there a reason for the heavily armoured flat top? Sure, a bomb exploding in the aircraft could burn like hell and they did. So perhaps modify the wood idea:
Wood can be plastified with formaldehyd for example. That makes it less yummy for earth's many inhabitants and increases it's characteristics as a duroplast from the fibrous organic foam it was before. This means that wood can stand more pressure for example. An organic foam that can stand more pressure, combine it with carbon fibres that are currently overused in construction because of the lack of a suitable foam for pressure durability (armoured concrete comes to my mind). Next interesting aspect are flameproof surface, a must have in current carbon designs. So maybe this experiment will lead somewhere and produce a new use of materials (there's currently a project to produce super-high wind power plants with wooden tubes as pillars, the tube part is very important for the structural stability due to the characteristics of wood). More on that later when I've done some experiments.

Flying aircraft carriers and rearmament planes:

Here's a link where someone wrote extensively on the subject. Rearmament in flight could provide a heck of capability, but will certainly come with a price tag. If the drone warfare continues we'll perhaps see some blimps replacing Xe groundcrews.

In some years time, when CVNs will be fitted with DEWs (in this case lasers) as CIWS, I'd exspect the power requirement to increase tremendously. The reactors on a Ford carrier will suffice, I guess, to provide the raw power. The technical challange, I assume, will be to release these amounts of energy in short, high intensity, bursts. And that's were I exspect some high power capacitors to come in handy. They can be prechared, and then use when required.
If you really want naval STOL to have greater capacity, I'd simply add canards to a design, able to induce early pitch up with additional lift, instead of having a complex TVC design prducing downforce at the tail. Plus maybe the jumping nose gear of the naval Rafale. Although these meassures only increase AoA and don't yet produce the nice lofted trajectory of a Ski Ramp.
My personal favourite still is to run a sturdy big wing area + canards design over a Ramp and have it perform Rocket Assisted Take Off