Whilst not wishing to create a Catobar vs Stovrl debate, I am curious as to whether this suggestion for catobar (which might not be viable as I haven't got aclue really!) might be installed more cheaply than previously indicated at a mid-life update.
As far as I know all cats have always been installed below deck with the result that the deck is completely flat. Would it be possible / cheaper? to install Emals above the deck to avoid lots of hacking away been bulkheads to fit all the kit? Obviously, this would mean that the cat would have to be in an area of the deck which was clear of any landing possibility (as it wouldn't be flat!). I assume that a solid metal rail and a large electro magnet would have to be on the surface of the deck, with the nose wheel in a kind of trolley on top of the rail.
I am sure I deserve some grief for this idea!!
Yeah, if you go back in the thread to before float out, you'll see an image of Goliath lowered onto a tug on the dockside.
I believe that the plan is for them to go in together, thus eliminating the need for LB03 to come out and go back in again as was done with HMS QE.LB03 is due to leave Govan any time and LB02 is due to leave Portmouth on August 5th. Will they be floated in to the dock together or will there be two separate operations?
What do you mean by "above deck?" He asked, trying to imagine a tractor trying to pull an airplane hither and yon, but not able to get from Point A to Point B by the most direct path, because there is some sort of "rail" gizmo that is 300 feet long and sticking up a couple of feet off the deck, effectively blocking its path.
Also, to answer the question, in part, concerning the reason for two towers; Enigmatically provided perhaps the salient reasons for that arrangement a couple of months ago, to wit: the location of the gas turbine and diesel generators. They aren't located down in the bilges as is traditionally the case with main propulsion engines. Those prime movers are not driving screws directly, so you could hang one from the CO's stateroom overhead and it would be just as effective as putting it anywhere else on the ship. I am of course being facetious, but the point is that not having to have the source of power directly in train with the electric drive motors, gives the designers a lot of options for machinery room locations.
Of course, both big marine diesels and gas turbines require a lot of combustion air, and that has to be drawn in from somewhere. Also, both types of engines also create a lot of exhaust gases, and they have to go somewhere. The best idea is collocating both the intake and exhaust plenums in the islands, where they can draw in air relatively high up so that a lot of salt spray does not come along with it, thereby creating a problem with corrosion control. Likewise, it is best to discharge those exhaust gases as high up and away from the deck, as the action of wind moving around those islands, coupled with the hot gases being discharged, may well create some pretty intense baffles above and astern of the ship that aircraft have to fly through. They shouldn't be affected to any great degree, but eliminating as many distractions as possible on final approach is always best.
Last but not least, is the "safety of flight vs. safety of navigation" situation. The design takes both into account and serves to diminish, if not eliminate altogether, the problem of "blind zones." I put together this picture of what the navigation team in USS Gerald R. Ford is going to have to deal with. Everyone else here has seen it, but it's worth another look just to remind folks of how potentially dangerous a blind zone can be.
Mike, is there any way that the inducted air is filtered to remove the brine spray, and also how are the exhaust gases cooled? With water spray? I should imagine this is important for reducing the heat signature of the ship?
I choose the worst times to go on holiday somewhere with no internet availability.
I'm a week late... but what a MAGNIFICENT sight QE is in her natural element. It seems like yesterday the first steel was being cut.
An eductor or "ejector" (same principle of operation; different working fluid) are the world's simplest pumps, in that they have no moving parts. Rather, they use fluid moving through a convergent-divergent nozzle to create a Venturi that draws another liquid into its discharge train and over the side, or vents it to the atmosphere. It is, in effect, the same principle used in the garden sprayer your Dad hooked up to the end of the hose in order to spray Mum's roses for aphids. Here is a bilge eductor schematic as well as a photo of the real thing. One might not even notice them when walking around the ship as they are so common:
Another version has a a portable "in-line eductor" (so called because it is literally installed "in line" in the hose used to attack a fire) that sucks Aqueous Film Forming Foam (or simply "AFFF"; p*r*o*n*ounced "A Triple F") fire hose from a five gallon can using a 3/4 inch diameter "pick-up tube" that is inserted into the can. The "working fluid" is provided by a one and one-half inch fire hose coming directly from a fire station, and the discharge side connected to another one and 1/2 inch fire hose with a Veri-Nozzle on its end. It literally IS that garden sprayer your Dad used, only a little larger. That arrangement is used to spray AFFF on a fire.
Another Damage Control use is the portable eductor for dewatering spaces. Again, a one and 1/2 inch fire hose provides the working fluid, and it discharges into a two and 1/2 inch hose which in turn discharges over the side. Like so:
But then, you didn't ask about all that, did you?
Well, cooling LM2500 stack gases the US Navy way is a two-part process. The first part, which is always functioning, uses what are essentially eductors to suck in cool air from the ambient atmosphere, and discharges it into the combustion gases exiting the stack. The interesting thing about this system is that the exhaust gases themselves are the working fluid. A portion of them are routed through the cooling system located around the internal periphery of the stack. Those gases moving through the nozzles create the Venturi, which then sucks the air from outside and discharges it into the exhaust gases. The second part, which is only activated when the ship goes to General Quarters ("Action Stations" to you lot), sprays sea water from the Fire and Flushing main directly into the stream of exhaust gases. It is only used during GQ because of the concern for corrosion.
Now, the crucial question is, "Does it work?" I don't know. I mean, it's never really been tested against a real, no fooling ASCM, has it? My sense is that it would help, but I wouldn't bet my life on it defeating an IR seeker head altogether.