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Bash the F-35 thred.


Belesarius

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My understanding is that VTOL basically removes your ability to loft any payload heavier than an AIM-9 and ruins your range; so it was the sort of thing that only made sense in a point defence interceptor role.

 

Is there any reason why the marines decided not to go for ski ramps on their carriers?

 

I'm not sure that a ski-jump helps that much if you have ninety degree thrust vectoring.

 

The ski jump allows you to convert some horizontal speed into vertical speed at low airspeeds.  You couldn't just pull the nose up on the plane because at those low speeds it doesn't really have the lift or control authority to do so.  In some of the really extreme trajectories with heavy loads off of a ski-jump, the fighter actually dives after it's been flung up and trades altitude for airspeed so it can get up to reasonable cruising velocity.

 

But with a STOVL aircraft, you're already converting horizontal acceleration into lift simply by tilting the nozzle.  If you convert a lot more of the horizontal velocity into vertical by hitting a ramp, you might end up below the stall speed, which is bad because the entire point of running in STOVL mode is to use takeoff loads that are greater than the vertical thrust limit.

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I'm not sure that a ski-jump helps that much if you have ninety degree thrust vectoring.

 

The ski jump allows you to convert some horizontal speed into vertical speed at low airspeeds.  You couldn't just pull the nose up on the plane because at those low speeds it doesn't really have the lift or control authority to do so.  In some of the really extreme trajectories with heavy loads off of a ski-jump, the fighter actually dives after it's been flung up and trades altitude for airspeed so it can get up to reasonable cruising velocity.

 

But with a STOVL aircraft, you're already converting horizontal acceleration into lift simply by tilting the nozzle.  If you convert a lot more of the horizontal velocity into vertical by hitting a ramp, you might end up below the stall speed, which is bad because the entire point of running in STOVL mode is to use takeoff loads that are greater than the vertical thrust limit.

Thanks for the explanation, but this was more to ask why the marines didn't use F-18s or something (off a ski ramp) instead of harriers.

 

It just seems strange that the ski ramp solution is so commonplace in other navies with small carriers, but the US service that specialises in them doesn't use this approach. 

 

Edit: also, the new QE carriers have a ski ramp and are designed for F-35. So what gives? Do the brits intend to just fling them off in the standard config and then recover them vertically? And, if so, why can't the marines? The same applies for the Invincible class and harriers. 

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Off the top of my head, I don't think that any carriers that use ski jumps are particularly small.  INS Vikramaditya is quite a bit larger than, say, a Ticonderoga class cruiser.  I think INS Viraat is as well.  Also, I don't know that ski jumps work terribly well with short decks.  The aircraft has to accelerate under its own power before it hits the ramp, so the amount of stuff it can carry is going to be a function related to the length of the run-up before it hits the ramp.  Apparently you can get CATOBAR-type weights out of an SU-33 if you have it accelerate the full length of the deck of the Kuznetsov.

 

So in short, I don't think that ski-jumps allow carriers to be much smaller than carriers with steam catapults.  I think they mainly allow them to be much simpler.
 

 

Edit:  More to the point, INS Viraat is larger than HMS Perseus, which was the first carrier to have a steam catapult.  The Invincible-class was a bit smaller than that, I think they were the smallest STOBAR carriers ever, but they were Sea Harrier only AFAIK.

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Off the top of my head, I don't think that any carriers that use ski jumps are particularly small.  INS Vikramaditya is quite a bit larger than, say, a Ticonderoga class cruiser.  I think INS Viraat is as well.  Also, I don't know that ski jumps work terribly well with short decks.  The aircraft has to accelerate under its own power before it hits the ramp, so the amount of stuff it can carry is going to be a function related to the length of the run-up before it hits the ramp.  Apparently you can get CATOBAR-type weights out of an SU-33 if you have it accelerate the full length of the deck of the Kuznetsov.

 

So in short, I don't think that ski-jumps allow carriers to be much smaller than carriers with steam catapults.  I think they mainly allow them to be much simpler.

So then what is the advantage of having a steam catapult carrier? Extra combat load?

 

Also, Invincible-class is 50m shorter than Wasp class. QE class is just over 20m longer than America-class. So the size difference seems to fluctuate even where similar plane types are considered.

 

Edit: All the recent US carrier classes with a steam catapult are in the 340-350m class. Kuznetsov is 300m and Kiev is 284m. So clearly ski jump ships are shorter overall even at their largest.

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As I understand it, Kuznetsov can get its Flanker-Ds into the air at MTOW, but the carrier has to be going full smoke steam forward, and it has to launch them from the rearmost launch position on the deck.

 

This rearmost launch position is way, way far back on the deck, so nothing else can be parked on the deck if it's launching fully-loaded birds.  This means that any other aircraft will need to be in the hanger and brought up to the deck by the elevator.  Sortie generation rate would suffer greatly.

 

Whereas something like the Charles de Gaulle a bunch of Rafales can sit, gassed up and gunned up and ready to go while another is launching.  To launch the next one they just need to get tugged a short distance across the deck to the catapult:

 

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As I understand it, Kuznetsov can get its Flanker-Ds into the air at MTOW, but the carrier has to be going full smoke steam forward, and it has to launch them from the rearmost launch position on the deck.

 

This rearmost launch position is way, way far back on the deck, so nothing else can be parked on the deck if it's launching fully-loaded birds.  This means that any other aircraft will need to be in the hanger and brought up to the deck by the elevator.  Sortie generation rate would suffer greatly.

 

Whereas something like the Charles de Gaulle a bunch of Rafales can sit, gassed up and gunned up and ready to go while another is launching.  To launch the next one they just need to get tugged a short distance across the deck to the catapult:

 

Okay, so it's a launch tempo thing then. Fair enough.

 

So why the hell do the Marines seem to take the worst of all possible worlds? Flat decks, no ramp, no catapult. Surely this is balls for being able to chuck harriers/F-35s into the air with a good combat load.

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As I understand it, F-35B was designed to fit inside existing LHDs.  It wasn't like a dedicated aircraft/ship team that was designed to work well together from the beginning.  I'm sure there would have been complaints, but the USMC was just so overjoyed to have something specifically designed for them that they didn't think to question it.

 

The VTO range/load of the F-35B is indeed terribad, but with a short takeoff it's much better.  Per this thread, the available load for short take off is nearly double the available load for vertical take off, which gives it some downright decent available mission profiles:

 

 

 

With two 1000# JDAMs and two internal AIM-120s, full expendables, execute a 550 foot [now 600 feet] (450 UK STOVL) STO from LHA, LHD, and aircraft carriers (sea level, tropical day, 10 kts operational WOD) & with a combat radius of 450 nm (STOVL profile). Also must perform STOVL vertical landing with two 1000# JDAMs and two internal AIM-120s, ~full expendables, & fuel to fly the STOVL Recovery profile.
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Again, interesting.

But again, I'm still completely in the dark as to why the marines went for baby flattops (sans steam gear) rather than, well, anything else. It really becomes more inexplicable the more I think about it.

Per the F-35B; I think I've said before that it's literally the best version of a harrier that the marines could have wished for. But then, this line of thought sort of wraps around to why the only plane the marines can use with their assault ships is the harrier in the first place.

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A couple of reasons occur to me:

 

1)  Steam catapults are a serious technical headache.  Even the proposed Ulyanovsk class carrier the Soviets were working on before their country imploded had a back-up ski jump as insurance if they couldn't get the steam cats to work.  This from the nation that first put men in space.

 

2)  The USMC getting their own carriers was never really in the cards.  A Wasp class isn't just a light carrier, it's also a floating hovercraft dock.  The USMC doesn't get big boats that are optimized for aircraft launch and recovery; that's the USN's job, and I suspect that any attempt to blur those lines would result in inter-service wrangling of a most dire nature.

 

3)  They already have the Wasps, with F-35B those ships just become more capable.  If the USMC did manage to get themselves a bunch of dedicated mini-carriers, Something like a Viraat but slinging F-35As and F/A-18Es off a small catapult or ski jump, they'd have to pay for the fancy new baby carriers, and then they'd need to keep the Wasps around to uses as hovercraft tenders.  Much easier to call in the USN to Spruance the shit out of anything hostile within several hundred KM of the coast with their real carriers.

 

4)  There's some sort of scaling factor to deck operations efficiency that favors large aircraft carriers.  Gerald R Ford class is supposed to be able to sustain 160 sorties per day with a surge capability of 270 sorties per day.  Charles de Gaulle is a little less than half the displacement, and has been throwing about 10-15 sorties per day at ISIS, with a surge capability of 100/day.  So, tonne for tonne, the US supercarriers are substantially more smitey than smaller vessels.  The break point is probably the size at which it becomes possible to conduct simultaneous launch and recovery operations.

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Steam cats are easier with a nuclear powered vessel, since you have steam to hand. QE-class run off gas turbines running generators, so to fit cats to them or anything similar you'd need a really large electric kettle. Not sure why the RN didn't go this route, given how much tea the UK gov runs off of I'd expect the idea to appeal to them. Electro-magnetic cats get around this, of course.

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A couple of reasons occur to me:

1) Steam catapults are a serious technical headache. Even the proposed Ulyanovsk class carrier the Soviets were working on before their country imploded had a back-up ski jump as insurance if they couldn't get the steam cats to work. This from the nation that first put men in space.

2) The USMC getting their own carriers was never really in the cards. A Wasp class isn't just a light carrier, it's also a floating hovercraft dock. The USMC doesn't get big boats that are optimized for aircraft launch and recovery; that's the USN's job, and I suspect that any attempt to blur those lines would result in inter-service wrangling of a most dire nature.

3) They already have the Wasps, with F-35B those ships just become more capable. If the USMC did manage to get themselves a bunch of dedicated mini-carriers, Something like a Viraat but slinging F-35As and F/A-18Es off a small catapult or ski jump, they'd have to pay for the fancy new baby carriers, and then they'd need to keep the Wasps around to uses as hovercraft tenders. Much easier to call in the USN to Spruance the shit out of anything hostile within several hundred KM of the coast with their real carriers.

4) There's some sort of scaling factor to deck operations efficiency that favors large aircraft carriers. Gerald R Ford class is supposed to be able to sustain 160 sorties per day with a surge capability of 270 sorties per day. Charles de Gaulle is a little less than half the displacement, and has been throwing about 10-15 sorties per day at ISIS, with a surge capability of 100/day. So, tonne for tonne, the US supercarriers are substantially more smitey than smaller vessels. The break point is probably the size at which it becomes possible to conduct simultaneous launch and recovery operations.

Thinking about a sort-of-equivalent issue the Japanese have been having with their 'helicopter destroyers', my suspicion is that your second point is close to the mark.

The marines can't have ski-jumps or catapults because that would signal to the navy that they want 'real' (ie: fixed-wing, conventional takeoff) carrier planes. They only got to have harrier because it happened to slip through the categorical crack. So F35B is just the illogical extension.

Basically, the reason the marines can't run F-18s off a ski ramp carrier has nothing to do with efficiency and everything to do with interservice politics.

 

Edit: having read up a bit more about the hilarious world of ships owned by the navy and run by marines (and planes owned by the marines but flown off of navy carriers) I should restate my thesis a bit here.

 

"The marines can't have ski-jumps or catapults because that would signal to the navy that they want an independent fixed wing air force. They only got to have harrier because it happened to slip through the categorical crack of being able to fly off of ships that they controlled. So F35B is just the illogical extension."

 

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"djcross" on the Key Publishing Forums has some interesting speculation on continued negativity on the F-35:

 

Quote

It is difficult to understate how much NAVAIR loathes F-35C.

They view it as an Air Force airplane shoved down their throats. Built in an Air Force factory and procured by an Air Force led Government Program Office with little input from NAVAIR. 

NAVAIR will harp about every little issue F-35C has while ignoring failures of NAVAIR-led programs like Super Hornet wing drop and drag or baby Hornet aileron reversal and drag or Osprey vortex ring state and nacelle leaks/fires.

NAVAIR is extremely political because NAVAIR is a government jobs program and they are fighting to keep their jobs - all 30,000 of them. Success of a non-NAVAIR program spells disaster for continued need for NAVAIR ans its 30,000 bureaucrats. 

The bottom line is to beware negative sniping coming from undisclosed "official" sources because their view is likely shaped by politics.

 

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