Curious business numbers.
Consider.
In 1960 the RN does a study on different CV sizes.
The low end is 42,000tons, the high end 68,000tons.
Cost wise we're told four 42,000ton CVs cost 180 million and four 55,000ton CVs cost 240 million.
by this we see that a ship of 59 million is factored as 60 million for a fleet of four and the 42Kton ship also has added a million to its quoted 44million
price for the average unit cost.
Ergo four 68,000ton CVs cost 272 million at 68 million per CV.
Which suggests that five 42Kton CVs cost 225 million which is 15 million less than four 55Kton ships but 38 million more than three 68Kton ships.
The 48,000ton CV is 10 million more than the 42,000ton ship in costs.
Build is said to be about 20% of the total through life cost.
So four 42Kton ship have a cost of 900 million overall cost compared to 1200 million ofr four 55Kton ships. A saving of 300 million for the smaller ship. The
68Kton fleet of four would cost 1360 million or 160 million more than the 55Kton fleet, though a fleet of three 68Kton ships costs 1020 million through life
which is 180 less than the four 55Kton ships. All of course at 1960 prices I might point out.
Even the 68Kton ship has just 59 NA39 Buccaneers (63 with 4 ASW helicopters) but even less OR346 types at 36 and thus falls short of the 96 needed for one
TAG, though two such ships are in excess of that number. Indeed at 36 its less than the 48 half TAG required, though smaller folded dimensions (especialy
width) could permit something closer to the desired figure. 36 implies a third of a TAG, suggesting you need three to provide the minimum air power for the
most demanding mission, which implies a minimum of five such ships.
Five 68Kton ships are 340 million or 1700 million through life cost.
This is driven by projections of an OR346 type as being 64ft long by 30ft folded width, most designs have a nosefold. NA39 is essentialy 20ft folded width (its
19ft 11 inches) and 52ft long (51ft 10 inches), though with drop tanks fitted its about 21ft wide folded.
So three OR346 types could fit in a hanger 100ft wide, but four NA39 types in the same hanger. Its of note that the OR346 designs tend to be about 21ft folded
width so the RN is being a pessamist on this front or looking at USN types.
The 55Kton ship does meet a third TAG at 32 OR346 aircraft, and in the interime can carry 44 NA39 types. So the RN would need three such ships operating
together to provide the necessary capability, implying a bare minimum of five such ships assuming no other task beyond the TAG for a limited time periode and a
long fallow periode after with maybe just one or two CVs available.
At 48,000tons you can have CV with a quater TAG of 25 OR346 types or 43 NA39 types.
However cut the folded dimensions of the OR346 down to say AW406 dimensions (52ft by 22ft or less) and a ship of 42,000tons should carry enough such
aircraft for one third of a TAG. Quoted figures are 18 OR346 types and 31 NA39 types.
An aircraft like the Type583 seems to fit that bill, since from my crude measurements of a small drawing its span with oversweep is under 23ft and its
length folded under 47ft. Thus in ten aircraft lengths a saving of 50ft is made compared to NA39, enough for an eleventh machine.
So to meet the RNs requirements with the OR346 type as they projected it, requires a minimum fleet of five 68Kton ships, if the machines are similar to NA39
then they can do it with a fleet of five 55Kton ships. But get the aircraft down to Type583 dimensions and a fleet of five 42,000ton ships can do the job.
Those studies found a CVs under 50,000tons there was insufficient space or weight for the catapults required, which where two 250ft stroke units. In fact
even the 50Kton ship has only one at this length and the other is at 225ft. The 42Kton ship has two 225ft units but I suspect they'd have to cut that down
on one to at least 180ft if not down to one 200ft and one 151ft units.
F4 without the Spey is likely to require the 225ft unit for take off with a useful load, USN CVs operated them with 250ft units of course.
And of course it should be noted that the Type 583 was expected to be operatable from the 151ft catapult and mk 13 arrestor gear and able to meet AW406.
