PMN1 said:This design was a double ended design with Sea Dart and Sea Wolf launchers fore and aft and the helicopter deck amidships.
Did any other country look at amidships helicopter decks?
Simulations showed it had little capability.
...which seemed much more cost effective than a larger number of smaller ships. The big gap amidships was intended to operate a Merlin [sic] helicopter, and the aesthetic treatment owed much to the pre-war Southampton class cruisers.
It proved to not be worth the effort. Many studies are carried out to investigate the impact of even unlikely requirements.
Longshaor said:What stikes me with this design is, even with something like the US RAST system or the Canadian Bear Trap, how safe would it really be to try to land a Sea King size helicopter amidships in bad weather?
Just call me Ray said:The only problem is that the superstructure now creates dangerous turbulence from the helicopter's own rotor wash, a reason why this hasn't been widely adopted now.
That's clearly not the only problem. The helicopter must match the ship's forward movement more accurately for longer than with an aft deck, while sliding in between the funnels; there is a much narrower angle of escape if a misjudgement is made. Even without turbulence, it must be more hazardous to land between two funnels than to land on an open space behind one. A direct approach from behind, slowing to match the speed of the ship, is not possible. Nor is any approach free from some interference from hot funnel gases.The only problem is that the superstructure now creates dangerous turbulence from the helicopter's own rotor wash,
Abraham Gubler said:Amidships flight decks can be found in such ships as the CG 47s. The only reason most ships have aft flight decks is because it’s much easier to design and build them that way. The FFG 7 was originally going to have an amidships flight deck but when the design requirement was changed from one to two LAMPS helos it was moved aft for more hangar width.
Abraham Gubler said:Smurf, TomS, Ray: a semantic debate with a group of people I can safely assume have had no actual, practical and professional contact with the naval helicopter community is not my idea of a fun way to spend the weekend. If you doubt me then I guess none of you have had the benefit of spending several days at a naval helicopter conference surrounded by said professionals and their constant focus on deck pitch. Nor have had the ‘fun’ of landing on even a slightly pitching deck in a Sea King helicopter.
In the real world the positioning of the Type 43’s flight deck presents very little superstructure obstruction for naval helicopters. The flight approach from the side is the same as used for landing on light carriers so hardly a shortfall. The worst thing about this deck is its low height above the waterline meaning it will probably have more sea spray to contend with. The advantage of the amidships position for reducing pitching movement is considerable.
Abraham Gubler said:This would indicate the flight path for landing on helicopters is up alongside the ship port side, match ship’s speed beside the flight deck, then come across to starboard until above the landing spot and then hover down to the deck. This is the same flight path as SHARs and SKs onto the decks of Invincible class carriers. When the sea is rough and the Invincible is pitching up and down they do so at right amidships. Why an Invincible can maintain a CAP in weather in which Nimitzes are running for lee shores.
Abraham Gubler said:Dear Longshar: Your question has in no way has ruffled my feathers. What got me upset was those OTHER posters who chimed in to decry anything against the conventional wisdom of accumulated readers of Wings magazine...
Landing on any non-carrier flight deck in a helicopter requires precision flying. Even if there is only one wall (aft deck) to worry about that is one vertical surface more than the number that you can safely fly your helicopter into. As any other structures on a ship is likely to be moving in the same direction and retaining the same distance from each other there is no need to be ‘twice’ as precise as your approach to the single structure. As long as you maintain the right clearance from the wall in front you won't hit the wall behind. Certainly in a sea state where the ship is pitching worrying about the wall behind you in addition to the wall in front of you is a small price to pay for a deck that is NOT going up and down by 20-30 feet...
If we have another look at the flight deck area of the Type 43 the helicopter flight path becomes quite evident. The ship’s FLYCO (aka control tower) is mounted on the port with clear fields of regard to port. Also the positioning of the forward and aft offset stacks means on the port side there is a clear avenue through the hot gas to the amidships flight deck.
This would indicate the flight path for landing on helicopters is up alongside the ship port side, match ship’s speed beside the flight deck, then come across to starboard until above the landing spot and then hover down to the deck. This is the same flight path as SHARs and SKs onto the decks of Invincible class carriers. When the sea is rough and the Invincible is pitching up and down they do so at right amidships. Why an Invincible can maintain a CAP in weather in which Nimitzes are running for lee shores.
Also worthwhile to note is the extreme length of what appears to be a hull knuckle on the Type 43. It extends ¾ the length of the ship. Such a knuckle would be needed to reduce the amount of spray up on the main deck level, amidships flight deck.
The Royal Navy knows an awful lot about flight operations in rough weather from carriers and frigates. Cost cutting and good enough philosophises has lead to the aft flight deck on the Type 24 and Type 45s. But like the RCN and back in the old days of the GIUK gap they did from time to time plan to build a ship that can operate helicopters in extreme sea conditions.
RP1 said:A T43 type arrangement might not be as good at accommodating growth in the helicopter size compared to, say the improved arrangement suggested by DKB for his double-ended Type 23 equivalent.
If you could link to that design (double ended T23) that would be nice.
RP1 said:The flight deck is offset to port with a small sponson (structural only - it's too small to contain anything). The aft superstructure is offset to starboard and is just wide enough to take the Sea Wolf FCR and 30mm (which was the naval RARDEN mount in some versions of the design). The aft VLSW silos are mounted in the deck inboard of the aft superstructure (roughly on the centreline) and clear of the flight deck. Hangar between the fwd funnels and split diesel-electric, split ops room, split accommodation and auxiliaries architecture.
Abraham Gubler said:RP1 said:A T43 type arrangement might not be as good at accommodating growth in the helicopter size compared to, say the improved arrangement suggested by DKB for his double-ended Type 23 equivalent.
If you could link to that design (double ended T23) that would be nice.
Interesting to look at design alternatives to the T43 like a more 'accessible' DD 963 type flight deck (see attach) and you retain access problems with the aft Type 909 houses you increase your burble with a bigger superstructure forward of the flight deck and you place all the exhaust into the flight path of the helicopter. Not to mention having to combine your separated engine rooms into a single area.
Interestingly the solution to much of this is in the Sea Dart missile. And in particular the cancelled block II that was to have TVC on its booster and ICWI homing for the seeker. This would enable the launcher to be displaced from the Type 909 directors. Much like on CG 47s and DDG 51s with the SM-2 missile and AEGIS. But even with the new missile the T43 would have to sacrifice unit propulsion on its length to ‘free’ up the rear access to the flight deck.
RP1 said:If you could link to that design (double ended T23) that would be nice.
The design was described in "The Future British Surface Fleet" and also in a RINA Warships Conference paper, about 1991 or thereabouts.
If you'll excuse the use of Shipbucket, I don't have the originals to hand:
The turbulent boundary layer about a moving streamlined body.
Also if a target was approaching from directly astern, how would a missile be gathered onto the target?
it looks like his ship was really designed with seakeeping first and foremost in mind.
There are one or two other factors relating to transom or cruiser sterns. DKB wrote on this a long time ago (Technical Topics No 4 - the Transom Stern in the Royal Navy, D K Brown, Warship 2, (5), 66, 1978.) He was also very keen on the 'knuckle' - see the Castle class OPV, though he did write (Nelson to Vanguard Note 66 p214): The value of knuckles is a matter of debate, often heated. The author's view is manifest in the 'Castle' class - though I may have overdone it in these ships.The cruiser stern is interesting, it's not common on a lot of modern ships but it gives far better protection against a following sea and a better ride than a modern transom type. Given that, the midships landing pad and the unusual bow it looks like his ship was really designed with seakeeping first and foremost in mind.