So the Dutch rebuilt Karel Doorman with an 8 degree angled deck and with 174ft BS4A steam catapult, how much further could a Majestic/Colossus Class be rebuilt after this?
Can you?
Make 1 or 2 of the centre lifts to the port edge making deck edge lifts, to increase hanger space?
Replace the boilers to High Pressure Boilers to increase speed of the ship to at least 28knots?
With Deck edge lifts and High Pressure Boilers can u fit longer catapult than the 174ft BS4A?
Badger1968
Did the modification of the melborne with 2 cat. and 8 degree angle deck, moving thre foward lift near the island.
I have the photo but I can loaded, son i put in PDF
Add to that the hig presssure boilers, 28 knots.
I like the idea.
Hi,
The PDF above looks potentially reasonable, as it keeps the forward lift inboard. As I understand it an issue with deck edge lifts, especially on smaller vessels is that when in the down position they are very close to the waterline, which can present a couple problems.
First off that means the side opening to the hull will be very close to the water, potentially allowing passing waves to enter. And secondly, when the lift is in its down position, there can be a chance that the lift edge can either impact or dig into a passing wave as the ship heaves, pitches and rolls in waves etc. Also as I understand locations near the forward quarter can also be bad for wave impacts due to both to potentially catching part of the "bow wave" and also potentially catching areas of wave build up at the "shoulders" of the hullform (where the hull transitions from its "pointed" bow shape into a more parallel waterline shape along amidships). As I understand it there were at times some operational issues with the forwardish deck edge lift on the larger HMS Hermes at times as well.
I think that there was an American Society of Naval Engineers paper many years ago where they did a seakeeping analysis of various aircraft carrying hullforms and issues with wave heights exceeding the height of the lower edge of a deck edge lift/hull side opening was found to be one of the limiters even on very large vessels.
As such keeping the forward lift within the hull would probably be a good idea. As for the aft lift, on ships like the French Foch and Clemenceau, they were able to get away with aft deck edge lifts (along with an enclosed forward lift) though they were much larger than the Colossus and Majestics, so you would probably have to do some form of studies to determine whether an aft deck edge lift would be acceptable, or whether you should also keep it enclosed, like in the pdf above.
HMS Hermes (showing bow wave and wave at shoulder catching appendages along side of hull)
Two catapults is interesting idea. How would an aft deck edge lift go on a Majestic class?
WIth High pressure boilers to increase steam capacity and speed makes the Majestic class sound like even better little carriers
Two catapults is interesting idea. How would an aft deck edge lift go on a Majestic class?
WIth High pressure boilers to increase steam capacity and speed makes the Majestic class sound like even better little carriers
My recommendation would be to push the bridge well forward, and place the starboard deck edge elevator immediately aft of the island. Maybe a second one behind it. Flight deck ops center would hang over the starboard elevator
And the port elevator also aft, roughly where the arresting gear is or maybe a little further aft.
As I recall the Argentineans seriously looked at an offer from a German firm to replace 25 De Meo boilers with four diesel engines of 15000 horsepower each and a donkey boiler for her catapult.
My recommendation would be to push the bridge well forward, and place the starboard deck edge elevator immediately aft of the island. Maybe a second one behind it. Flight deck ops center would hang over the starboard elevator
And the port elevator also aft, roughly where the arresting gear is or maybe a little further aft.
I wonder how hard it would be to move the bridge forward? I think having at least the aft lift should be deck edge on the starboard side, with maybe the forward lift aswell. Can you put something Infront of the lifts to deflect waves.
As I recall the Argentineans seriously looked at an offer from a German firm to replace 25 De Meo boiler with four diesel engines of 15000 horsepower each and a donkey boiler for her catapult.
That would be an interesting rebuild during the 80s, though i dont think it would be realistic during the 50s n 60s that why i suggest high pressure boilers at least 600psi+
I wonder how hard it would be to move the bridge forward? I think having at least the aft lift should be deck edge on the starboard side, with maybe the forward lift aswell. Can you put something Infront of the lifts to deflect waves.
As I understand things, the hard part is the stacks and uptakes. Those can be moved, but it's a lot of redesign work.
My thought was to leave them where they come through the flight deck but rearrange the island around them. You can move the island overall at least 30ft forward and maybe 50, all without messing with the uptake locations. And then you add a whole new Pri-Fly area wrapped around the inboard side of the stack.
Put the port elevator where the deck crane is located, move the deck crane aft of the port elevator.
Borrowing wiki's photo of HMAS Melbourne here, you can see where the uptakes/stack are in the middle of the island. Which also means you can see how far forward my proposal would move the island.
Note that if we're slapping an angled deck on there and widening the flight deck, that involves relocating where the uptakes are anyways so we can do a better job in making the island work without having busy parts of the structure in poorly-accessible places.
As I understand things, the hard part is the stacks and uptakes. Those can be moved, but it's a lot of redesign work.
My thought was to leave them where they come through the flight deck but rearrange the island around them. You can move the island overall at least 30ft forward and maybe 50, all without messing with the uptake locations. And then you add a whole new Pri-Fly area wrapped around the inboard side of the stack.
Put the port elevator where the deck crane is located, move the deck crane aft of the port elevator.
Copy i can visualise it now, so move the bridge forward and than put a deck edge lift behind the island. Which lift would u replace with the deck edge the fwd or aft lift?
The above seems to ignore the machinery layout in these ships as originally designed.
Their machinery was in two widely separated combined boiler / turbine spaces filling most of the width of the ship. Each unit consisted of 2 boilers, a single turbine and a 500kw turbo generator, with each unit driving one of the two shafts. The forward unit was directly under the funnel. The after unit was about 50ft aft of the forward unit, placing it about half way between the original island structure and the after lift. Funnel gases from the after unit then had to be trunked forward at a level just under the hangar deck to meet those of the forward unit at the base of the funnel uptake. In between were two compartments containing the midships aviation fuel tanks. AIUI, the forward unit drove the port shaft and the after unit the starboard shaft.
So any plans to move the island or insert a new hull extension needs to take the locations of those machinery compartments into account. Attempting to move those rapidly becomes expensive with moving shaft lines or boiler uptakes.
As I recall the Argentineans seriously looked at an offer from a German firm to replace 25 De Meo boiler with four diesel engines of 15000 horsepower each and a donkey boiler for her catapult.
Interesting. There was a proposal for something like that with Foch/São Paulo in the early 2010s, but I doubt it was anything other than an idea to stave off São Paulo's decomissioning.
Not sure a second catapult would add much capability given the very small air group and strike size. In practice it would have been hard to range more than 10-12 aircraft for a strike and then recover the same number using the bow deck park and an enlarged deck park behind the island (as on 25 de Mayo and Minas Gerais)..
Moving the island forward potentially makes sortie generation worse by reducing the size of the bow deck park and slowing down recoveries... as more aircraft would have to turn 180 degrees and head towards the midships deck park behind the island.
Basically hard to get much more out of these than what the Dutch and Argentinians achieved with Karel Doorman/25 de Mayo.
I’m sure I’ve read that was done with HMS Centaur although the plug was longer. It was done during the ships build because it was realised after keel laying they needed longer flight decks…. Must have been a memorable day at the office when that they said “no we’re serious”.
Not sure a second catapult would add much capability given the very small air group and strike size. In practice it would have been hard to range more than 10-12 aircraft for a strike and then recover the same number using the bow deck park and an enlarged deck park
One advantage would be to quickly launch the strike aircraft and than be able to move the carrier away from the area, eg HMAS Melbourne does a raid against Indonesia airfield.
How much extra hanger room would deck edge lift add?
How much extra SHP would be require from high pressure boilers and turbines to increase speed to 28-30knots?
I’m sure I’ve read that was done with HMS Centaur although the plug was longer. It was done during the ships build because it was realised after keel laying they needed longer flight decks…. Must have been a memorable day at the office when that they said “no we’re serious”.
Well that is not true. There were no significant dimensional changes made to the class between the sketch design of May 1943, their approval in Feb 1944 and their completion to the 1947 revised design.
From Friedman the figures are sketch design May 1943 / as built after 1947 redesign.
Length between perpendiculars (bp) - 650ft / 650 ft
Length waterline - 685ft / 686 ft
Length overall - 736ft / 736-738ft
Beam waterline - 90ft / 90ft.
Centaur laid down 30 May 1944, launched 22 April 1947
Albion laid down 23 March 1944, launched 6 May 1947
Bulwark laid down 10 May 1945, launched 22 June 1948.
Even Hermes had the same length bp and waterline beam but was 744ft overall with a slight reshaping of bow and stern.
The Centaurs were of course 20ft longer bp, 36ft oa & 43ft longer oa compared to a Colossus / Majestic.
Copy i can visualise it now, so move the bridge forward and than put a deck edge lift behind the island. Which lift would u replace with the deck edge the fwd or aft lift?
Forward lift becomes the starboard deck edge lift, aft lift becomes the portside deck edge lift. And we add a third lift, brand new, to the aft starboard side.
That would make the hangar deck another what, 75ft longer? 100ft longer? by extending the hangar through to the former lift areas.
So any plans to move the island or insert a new hull extension needs to take the locations of those machinery compartments into account. Attempting to move those rapidly becomes expensive with moving shaft lines or boiler uptakes.
That's why my basic plan was to not move the uptakes at all, and rearrange the island around the uptakes.
Now, if we're widening the flight deck that means we're already spending the design time to relocate the uptakes so we can do an optimized island design in that case.
No, there's only one island since the uptakes are already trunked together, it's just that the uptakes are at the aft end of the island now instead of in the middle of the island for the stock flight deck.
I don't think there's enough flight deck space for two islands, even if we widen the flight deck.
I have come to the conclusion that by the mid to late 80s the technology exists to produce an "Uber Majestic ". There's just one problem thier hulls are about to collapse from stress and old age.
It might be more prudent to build a Majestic replacement carrier.
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