Because nuclear doesn't buy you that much in reality. You don't need F76 for the engines, but you still need F44 for the jets, plus ordnance (a US Nimitz-class will RAS ordnance every three days during high-intensity ops - even their bomblockers aren't bottomless) and especially food.But can you answer why we went for a dieso electric propulsion system in the 1st place rather than nuclear, the frogs managed it with the Charles De Gaulle, and that is 20, 000 tonnes lighter than the QEs.
Meanwhile, nuclear means qualified watchkeepers which we're desperately short of anyway, higher costs, and political screams when you try to dock in many ports that don't want "noocular warships" exploding while moored up.
Again, even the USN are struggling to make the case for nuclear power on carriers, and while the French got one built their experience with it doesn't really fill me with enthusiasm.
About one for one, when you cost it out over the lifecycle: maybe less (the pilot training is shockingly expensive).As for my point about off the shelf aircraft, this would have been a stop gap until a suitable 5th generation aircraft was tried and tested, after all, how many F18s can you buy compared with 1 F35B?
To repeat an earlier post on the costs and difficulties of qualifying pilots for arrested landings...
Some big broad handfuls, using dollars because I'm swiping numbers from the USN's experience; it'll drop short because it's mostly just looking at flying hours, no other costs. The following is almost certainly wrong, but it's wrong as an underestimate...
Firstly, you've got the flying hours for deck training; take a qualified fast jet pilot who can land on concrete, put them in something like a T-45 Goshawk (training plane not destroyer), and teach them to land on a moving carrier. That's about two or three hundred flying hours (40 weeks, 125 hops) for the USN; $1,500,000 immediately just in T-45 flying hours, plus you actually need the T-45s to fly (about $30 million per airframe at last rough check; the USN gets about 60 hours per aircraft per month out of them, considered excellent, but that ends up needing half an airframe per trainee in the pipeline). Consider that the USN's washout rate hovers at around 50%; if you want to sustain 48 trained pilots on an eight-year service commitment, you'll need to train about fifteen a year, so eight T-45s up front ($240 million) and $22.5 million per year steady state. (Just in airframes and flying hours, no salaries or other costs)
At that point you've built a force of 48 pilots who can land a T-45 on a carrier: transition training to F-35 will need more hours on a very expensive-per-hour Lightning ($32,000 per hour or so), and then the skills need to be maintained; the USN estimates their pilots, aboard a carrier in home waters during workup, are flying 30-32 hours a month to build and sustain their skills (about 50% more than their land-based contemporaries; all the usual requirements, plus staying current on carrier operations). Handwave away conversion courses (land-based F-35B pilots will need to transition too) but it still gets very expensive.
Ten hours, per pilot, per month, for an air wing of twelve Lightnings in normal jogging to stay carrier-competent; that's pushing fifty million dollars a year just to keep the embarked pilots current. If you want to surge to a larger air wing, you'll need warning time and some serious workup (and the capacity to conduct it, which will otherwise be sitting around idle annoying the Treasury) because a lot of your force are out of practice and will need to refresh; the USN reckon on having to requalify after each shore tour.
See where the costs start coming from? We're not looking at instructors and simulators, nor are we considering the cost of having an aircraft carrier steaming around in the SCXAs chasing the wind, plane guard helo aloft, while a succession of nuggets do touch-and-goes or arrested landings on her deck, and there's the risk of accidental losses; the US Navy and USMC's aviators suffer 20-odd Class A mishaps (loss of life or more than a million dollars' worth of damage) per year, with about ten aircraft lost and about ten dead, each year. Even assuming we're operating one carrier to their eleven, that's an aircraft and pilot a year gone; even if it's a (relatively) cheap T-45 that's an extra thirty million a year and a hole in the ORBAT.
So to qualify forty-eight for a surge, and keep twelve pilots up and skilled, we're looking at $240 million up front and a bit over seventy million a year in running costs, even assuming no accidents. Over a thirty year life, that's more than two billion dollars in extra costs, in order to save $800 million on the airframes because the -C is cheaper than the -B. (Lose one T-45 a year in landing accidents, which is in line with USN experience, and the cost goes up by another billion)
See why the numbers simply don't add up for CATOBAR, and why it actually becomes a very inflexible asset when all the realities of trying to surge the embarked airwing to 30-odd F-35Cs hits the rocks of "just give us a year and a shedload of cash to get all our pilots back in date for night landings..."?
Another lesser issue is that, given that we're unlikely to be using the QECVs as pure carriers but as hybrid CV/LPH, STOVL trades off some range and payload on the Lightnings (which are still awesomely better than SHar regardless of version) but sterilises less deck space and needs less time to recover F-35Bs at the sort of high-stress "too many landings in not enough time" moments that high-intensity warfighting generates.
But, the main point is that it's difficult and expensive enough to qualify pilots for CATOBAR ops that even the USN struggles with it over eleven carriers and their relatively bottomless budget, and nations with one or two CVs find it very difficult (cruel comments that the reason the recent Kusnetsov cruise only ever had one Flanker airborne, was because they were down to one pilot who was deck-qualified for their STOBAR ops, are unverified but funny)