Another (smaller) carriers and jets question - integrating aircraft and ship

The Essex class, even with an angled deck added, were still smaller than the Battle class carriers (Midway, Coral Sea and FDR). I don't see how the Essex class could have operated the Phantom if the Battle class could not.
They flew F-8 Crusaders and A-4 Skyhawks (replaced by A-7s). F-4 and A-6 were too heavy.
 

Yokel

LE
I thought that Midway and Coral Sea did, and in their last few years they operated the F/A-18 Hornet. The Essex class never did, which may have been a show stopper for the RN, as well as all the extra manpower needed. As far as I know, there was a version of the F-8 Crusader proposed for the RN - maybe this was the reason why?

@ABNredleg in the case of the F-4 I am guessing that the landing speed would have been a factor with landing aboard smaller decks, more so than being heavy, but a catapult launch with a shorter stroke would have been another issue.

Too fast for a safe landing, too heavy for a safe launch.
 
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I thought that Midway and Coral Sea did, and in their last few years they operated the F/A-18 Hornet. The Essex class never did, which may have been a show stopper for the RN, as well as all the extra manpower needed. As far as I know, there was a version of the F-6 Crusader proposed for the RN - maybe this was the reason why?

@ABNredleg in the case of the F-4 I am guessing that the landing speed would have been a factor with landing aboard smaller decks, more so than being heavy, but a catapult launch with a shorter stroke would have been another issue.

Too fast for a safe landing, too heavy for a safe launch.
I was referring to the Essex class.
 

Yokel

LE
I was referring to the Essex class.

I know. I should have learnt by now not to reply to different posts with quoting and separating the two posts I was referring to. However the point about landing speed is that as every extra knot adds to the kinetic energy that has to be dealt with by the arresting system, which is a safety issue. Mind you, the F-8 was designed for the Essex class and use the variable incidence wing to improve low speed lift during the landing and to improve lift during launch.

As for the ships themselves, were they ever retrofitted with things like stabilisers?
 

exspy

LE
The Essex class, even with an angled deck added, were still smaller than the Battle class carriers (Midway, Coral Sea and FDR). I don't see how the Essex class could have operated the Phantom if the Battle class could not.

Excuse me for quoting myself. I was wrong, Phantoms did operate from the Battle class carriers. It was, as stated, the Tomcat which could not be operated from them.

I promise not to poke my head up above the parapet again.
 

Yokel

LE
Excuse me for quoting myself. I was wrong, Phantoms did operate from the Battle class carriers. It was, as stated, the Tomcat which could not be operated from them.

I promise not to poke my head up above the parapet again.

Why? It all adds to the debate. Good low speed characteristics make for safe(r) landings and a lower accident rate, for two reasons. The pilot has more time to line up etc, and less speed means less kinetic energy has to be absorbed - EK=1/2MV^2. The Hornet had a lower landing speed, which is why is could land aboard Midway and Coral Sea. It also had things to reduce pilot workload during those last fee seconds.

The advent of V/STOL aircraft (Harrier/Sea Harrier/Yak-38 Forger) give the small carrier a new lese of life, as it eliminated the need to accelerate to the speed where enough airflow over the wings provided lift, and for arrested landing and judging landing to within a splint second. It also offered the ability to operate in rougher seas for the smile size of carrier, not need sailors to man catapults and arresting systems, and reduced training requirements as constant carrier landing practice was no longer needed. This was at the expense of things such as speed, range, and payload.

Until F-35B that is... Advanced V/STOL research took place on both sides on the Atlantic from the mid 1970s onwards.
 

Yokel

LE
Talking of adding to the debate - I wonder why when a few jets were attached to the CVS conversions (of the Essex class) to protect the ASW aircraft, the US Navy opted for the A-4 Skyhawk, presumably controlled from the ship, instead of the F-8. Were ASW operations expected to take place in worse sea conditions - which might explain why a slower aircraft would be a better bet for carrier operations? Shame they never gave the A-4 any sort of radar.
 
Talking of adding to the debate - I wonder why when a few jets were attached to the CVS conversions (of the Essex class) to protect the ASW aircraft, the US Navy opted for the A-4 Skyhawk, presumably controlled from the ship, instead of the F-8. Were ASW operations expected to take place in worse sea conditions - which might explain why a slower aircraft would be a better bet for carrier operations? Shame they never gave the A-4 any sort of radar.
When the first VSF squadrons were formed all the ASW carriers had hydraulic catapults, whereas the attack carriers were upgraded with steam catapults. They couldn’t operate the F-8 due to weight considerations so they went with A-4s. The other consideration was deck space. ASW carriers did carry AEW planes, which could control the CAP.

Interestingly, they tested the A-4 with ASW torpedoes, although I haven’t found anything to indicate they were deployed.

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Yokel

LE
When the first VSF squadrons were formed all the ASW carriers had hydraulic catapults, whereas the attack carriers were upgraded with steam catapults. They couldn’t operate the F-8 due to weight considerations so they went with A-4s. The other consideration was deck space. ASW carriers did carry AEW planes, which could control the CAP.

Interestingly, they tested the A-4 with ASW torpedoes, although I haven’t found anything to indicate they were deployed.

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I suppose you have not got a link for any articles about the A-4 deploying ASW torpedoes? I have heard similar stories about proposals with all sorts of jets - including RN ones.

Am I right in assuming that the A-4 had a lower landing speed that the F-8 too, so even if the CVS ships had been fitted with steam catapults, it would have been more risky to try to recover an F-8 in heavy seas than an A-4?
 
I suppose you have not got a link for any articles about the A-4 deploying ASW torpedoes? I have heard similar stories about proposals with all sorts of jets - including RN ones.

Am I right in assuming that the A-4 had a lower landing speed that the F-8 too, so even if the CVS ships had been fitted with steam catapults, it would have been more risky to try to recover an F-8 in heavy seas than an A-4?
Nothing about deploying torpedoes, although apparently they were valuable in forcing diesel subs to submerge - their speed and range gave them the element of surprise.

F-8 had a very high landing speed, as well as very high accident rate, so I imagine it would be a nightmare landing on an Essex during bad weather.

I suspect that the main reason they went with small detachments of A-4s (they usually deployed four aircraft) is they were simpler, safer, and created far less of a burden on the carrier. A simple fighter with a couple of Sidewinders was all you needed to drive away bombers and patrol aircraft.
 

Yokel

LE
Australia and Argentina also operated the Skyhawk from smaller carriers, and both had the S-2 Tracker. During the Falklands War there was potential for Argentine Skyhawks launching from their carrier, with no radar but aided by S-2 types, going up against RN Sea Harriers. That would have been the first such event since the Battle of Midway. It also would inform discussions about smaller carriers and STOVL operations.

I should have put the French F-8 and the modifications it needed into the thread title.

As for the jets with torpedoes, I believe that was from the days of early ASW helicopters that did not have enough power to carry both dipping sonar and ASW weapons. The extra power of the SH-3/Sea King was a real step forward.
 

Yokel

LE
I have amended the thread title as the thread discusses things other than the integration of the F-4K and SuE with the carriers intended to operate them, to wider ship/aircraft integration issues. This is a good thing is it is poorly understood by the self appointed experts in the media.

I cannot resist quoting myself from the CVF and Carrier Strike thread - here:

Meanwhile - here is my fish tank analogy:

Ship size - I think a useful analogy is a fish tank. Years ago I was chatting to the guy in the pet shop, and he said that many people seem to think that smaller tanks must be easier. However, this means a smaller volume of water, so it becomes more sensitive to changes in pH, salinity, and so on. Add to that plants which consume Carbon Dioxide during the day but not at night, and fish which consume Oxygen, fresh water, food, and produce urine and excrement.

Keeping your fish healthy depends on them having enough room to swim, breathe, urinate, etc without interfering with each other. It also depends on the filters and Oxygenation, and diligent cleaning. So for the same number of fish (take the hardy Goldfish as an example), a smaller tank may be smaller to buy, the cost of each fish or plant will be the same, but the cost of the pump/filters/etc will be similar whatever size of tank you select. Therefore the smaller tank is only a small saving when everything is considered.

Adding more fish later may be an issue, as each fish needs a certain amount of space for health. The more fish per volume of water the greater the problems, the more critical things like filtering, Oxygenation and cleaning become. The larger the tank, the less sensitivity there is to small changes.

Instead of a glass/plastic tank, think of a steel hull/superstructure (typically about 10% of a warships' cost). Instead of filtering/Oxygenation think of things like the three phase electricity supply, chilled water supplies, etc (not to mention accommodation for people), instead of fish think of systems (or aircraft) that transmit and receive electromagnetic energy, demand physical space, need to be fed with electricity, chilled water, hydraulic oil, etc, as well as being operated and maintained by people.
 

Yokel

LE
If you ignore the hyperbole about Pilots carrying sidearms and knocking on the door, this quote by @P2000 in this post is an example of good engineering having its wings clipped by cowardly politicians and woeful project management:

OK people gather around for a story of shame and misery, of betrayal and treachery, of the hideous oppression of poor ship designers and the foul fiends who lead them. Weep at their plight, o people, for it was indeed shameful.

When the French Navy realized they had to replace Clemenceau and Foch back in the early 1980s, the Government was very reluctant to release the cash. They only agreed to the construction of two ships if they were exact replacements for the two carriers due for scrapping. This meant they were restricted to 27,000 tons normal, 32,000 tons full load and a length of 240 meters. Also, that they should carry a group of around 32 aircraft. That, by the way, made them look very much like an Essex class (which isn't surprising, the Foch and the Essex are very, very similar in design terms).

Length first. This was actually set by the available drydock. At that time, DCN had a stranglehold on French shipbuilding and required their facilities to be used. The maximum length that could be accommodated within their available drydocks was 260 meters. That immediately lead to a problem. Aircraft are much higher performance than they were in teh 1950s, they require bigger decks to operate from. They needed much more deck space so the ship had to be crowded into that available length. The real joke is that just across the port is the biggest drydock in the world, it was used to build the SS France pre-WW2. But, it couldn't be used, DCN didn't own it.

So, why not lengthen the drydock? Well, the problem was that at the landward side, the extension to the drydock was blocked by a toolshed. Why not move it? Well, the toolshed was owned by the Ministry of the Interior, the drydock was owned by DCN, part of the Ministry of Defense. Moving the toolshed should cost roughly US$100,000 - who should pay? Interior said Defense, Defense said Interior, they never agreed and the tool shed is still there. So was the length restriction of 260 meters.

So, to get around the problem, the designers adopted a solution by which an unusually wide flight deck was adopted. This lead to a rolling problem (its a matter of vertical movement, for the same degree of roll, a wide ship has a much greater vertical movement at its outer limits than a narrow ship so a wide ship has to roll less if its extreme vertical movement is to be within tolerable limits). In order to reduce roll to an acceptable level, the French had to include an elaborate computer-controlled anti-rolling system. This works well but its wasted weight and space, both of which were at a premium.

The restricted length gave another problem. The aircraft on board have to be accelerated to a specific speed in a specific distance. The catapults available couldn't do that. So the French designed a short, high-acceleration catapult. It worked OK but dummy tests showed the force transmitted to the pilot was very, very close to that which would break his neck. Since French pilots carried sidearms and were pounding on the door wanting to discuss this with the catapult deisgners, it was decide dto abandon the new catapults.

Instead, the French bought American C-13-3 catapults. Problem was that these were much longer than the French design. Now, some technicality. On the Pepe le Pu, the flight deck is the strength deck, this is what gives the hull girder its integral strength. Cutting two long slots in the strength deck severely compromises the strength deck and thus weakens the overall hull strength. Worse, because the design of the carrier was restricted in size, the two catapults couldn't be installed in the bow, there was only room for one there. The other had to be put in the waist. That meant not only were the slots cut in the strength deck long, they were one-behind-the-other and overlapped. That critically weakened the flight deck. The only option was to strengthen the flight deck by thickening it up and, because of its area, that cost a lot of weight.

At the other end of the deck, the French also designed a very fierce arrester wire system to bring teh aircraft to a halt quickly. It worked extremely well, the arrester wires stopped the back half of the aircraft perfectly. Unfortunately, the front half kept going. It was decided that this was not desirable (the pilots were pounding on the door again, this time with sidearms drawn) . The only option was to install a conventional arrester wire system and extend the angled deck forward. This interefered with the bow catapult and meant the carrier could not launch and recover aircraft simultaneously - a major limitation.

Later, it was found that they hadn't lengthened the angled deck enough, it was three meters too short and the heavier aircraft would still be moving forward when they reached the end and vanished over the edge. It had to be extended post-completion.

The travails of the design team weren't yet over. The problem now aorse of the elevators. They'd decided on two elevators, fair enough for the proposed air group. The problem was that the flight deck was the strength deck and stress levels there were already critical. Even deck edge elevators require a major cut-out in the deck and weaken the deck significantly. Now, the conventional solution is to put elevators on both sides of the ship, that's good from damage control and from weather shelter perspective. Unfortunately, that means there's a cut out on both sides of the ship, doubling the weakening effect. Having both elevators on the same side of the ship doesn't do that. So, the French had to put both elevators on the same side of the ship. The question was, which side? If they put them to port, they would obstruct the landing deck, they had to go to starboard, the same side as the Island. Hold that thought.

Now we need a little digression. For mostly political reasons it had been stipulated that the ship would need nuclear power. The problem was the French didn't have the money to develop reactors specifically for her, they had to use the K-15s off the shelf. Now, the K-15 was designed at a time when the French were hoping to export nuclear-powered attack submarines. To get around the nuclear non-proliferation treaties, they designed their reactors to use low-enrichment fuel called "caramel". This had two impacts, it lowered the power density of the reactor and it reduced the life between refuellings. Neither mattered too much in teh putative export SSN. It turned out they both mattered a lot in a CVN.

The French Navy adopted the K-15 for its own use. In theory at least, this isn't such a dumb decision. Caramel is around 15 percent enriched, the fuel used in US or British submarines is a lot more (like multiples) more enriched than that. However, highly enriched fuel needs special processing and reprocessing plans that caramel doesn't. So, in theory at least, its possible to argue that the financial and operational costs of using low enrichment fuel can be offset by the elimination of the reprocessing plant. Implicit in that approach (which turned out not to be the case by the way) is designing the ship so that refuelling the reactors is quick and easy.

This meant designing her so there was a path through the ship, straight down to the reactor room. For weight reasons, the reactor room has to be more or less amidships, so this path had to be amidships. Again, structural reasons meant that this non-load bearing path (essentially a hole cut right through the ship's girder) couldn't be in parallel with one of the elevators (stress levels in the flight deck would pass critical).

Back to the held thought on elevators. The refuelling soft patch had to be between the elevators, meaning the two elevators would have to be both starboard side and very well separated. The island (a structure that imposes significant loads on the ship) also couldn't be parallel with the reactor access soft patch. That meant it had to be either forward of the fore elevator or aft of the rear elevator. The latetr was impossible, it would have perched the island right on the stern.

The forward position had to be chosen. This is good for ship handling, lousy for aircraft operations.
The French tried to claim that the forward position was selected because it sheltered the aircraft from the weather. The world laughed.

Still more problems. Flight deck space was critical, the minimum required was calculated and subtracting that from the space available gave the space for the island. It wasn't very much. All the antennas were compressed into a small area and they all interfere with each other. That means that many systems can't be operated simultaneously including such things as comms, search radar, fire control, radar et al.

More problems. The design chosen had a wide hull for its length. That's bad for speed. The French did a lot of research into hull forms, a lot of calculation and a lot of trials with a sub-scale model. None of which helped. Pepe le Pu was designed for 27.5 knots; it was admitted that there was no possibility of getting her past 25.5.


Other problems emerged as well. The reactors lacked steam capacity to operate the catapults properly (sustained launching of aircraft would deplete the steam capacity and have a serious effect on the ship - not just on speed). On trials that was a problem, but a bigger one was that the screws fell apart. Partly this was a production problem; the screws had been improperly cast and contained voids, but the other factor was intense vibration at higher speeds. After her screws fell apart, they had to be replaced by a set from one of the older carriers. They were unsuitable and restricted the ship's speed to "less than 23 knots" (actually 21.4). When her new screws arrive (200
8)
, her speed will increase to above 23 knots (actually 23.5 her real maximum operational speed, she can do a bit more but the vibration is intense and its not recommended).

The ship had other operational problems as well, internal flow is not good, supply of munitions is difficult, all the things one expects of a new design team. By the time the design process was finished, the ship weighed 36,600 tons standard, 42,500 tons full load (35 percent and 32.8 percent overweight respectively)

She would have been a much better, more capable ship if she'd been designed as a dead dinosaur powered STOVL carrier but that would mean the French buying Harriers.
 

Yokel

LE
Oi, Yokel - did you get the PM?

Yes. Sorry I have not yet replied. I have not been able to successfully integrate the different aspects of my life and deconflict activities that may interfere with each other. A very badly run carrier, with a fast aircraft (with poor throttle control and poor over the nose visibility) trying to land on a small deck moving in a wild sea, is a reasonable analogy for my life.

Some tosser spread false information throughout the ship, and messed around with the landing aids, and I struck the ramp.
 

Yokel

LE
Despite the size of the Forrestal, Kitty Hawk, and Nimitz classes, the United States also came close to a ship aircraft integration fail.

Politicians wanted to put a version of the F-16 aboard carriers

Shortly after the F-16 won the Air Force's new Air Combat Fighter (ACF) contract in 1975, then-Secretary of Defense James Schlesinger pushed the US Navy to adopt the new fighter as well.

The F-16 had performed well in its pursuit of the Air Force contract, and if the Navy could also find use for the Fighting Falcon, Schlesinger reasoned, the Defense Department could procure the jet in higher numbers and streamline logistics for both branches.


But what about the details?

In order to withstand carrier landings, heavier duty landing gear had to be affixed to the Vought 1600's belly, alongside the standard carrier equipment like a landing hook. The fuselage itself was made stronger and in order to offer the engagement range the Navy needed, a pulse-doppler radar for beyond visual range targeting was also added.

All told, the structural changes needed to make the F-16 into the Vought 1600 added more than 3,000 pounds to the aircraft. Further changes were made to the fuselage and wings as subsequent iterations of the Vought 1600 came to fruition. The V-1602, for instance, had even more wing area at 399 square feet, and was given a heavier GE F101 engine.


However, how compatible was it with a carrier deck?

The Vought 1600's low-lying intake located just above the nose-wheel was considered a real risk on the flight deck of a Navy carrier, as it could literally suck unsuspecting sailors straight into it. This wasn't the first time Vought faced this sort of criticism, as the pilot-favorite Vought F-8 Crusader's large, low intake had already earned it the nickname "the Gator," because of its tenacity for gobbling up sailors.

There was also the issue of landing...

Holloway stood firm, however, highlighting the concern of his engineers that the Vought 1600 was apt to bang its engine on the flight deck during carrier landings, which could cause damage to both the deck and the aircraft. When the men gathered in Schlesinger's office argued that problems like that could be mitigated with better pilot technique, Holloway grew frustrated.

Clearly, anyone preaching about improved pilot technique to offset a fighter's design shortcomings had never attempted to land on the pitching deck of an aircraft carrier that was barely visible against a seemingly endless backdrop of stormy seas during nighttime operations.
 

Yokel

LE
QinetiQ - What does the future hold for Ship Air Integration?

...it is QinetiQ’s view that Ship-Air Integration should take place as an integral part of the ship’s design, from the devising of early CAD drawings, to the thoughts of the first cutting of metal.

By doing this, the potential for design mistakes can be avoided and the aircraft, whether it’s helicopter, fixed-wing, or as is increasingly common, UAS, which is being considered as an integral capability, rather than the traditional highly-desirable add-on. QinetiQ is uniquely placed to support this evolution within the UK as it maintains years’ worth of data from its previous trials, along with the most modern Air Flow Air Pattern data and Computational Fluid Dynamics, giving the capability to combine a read-across from history with accurate modelling, thus providing expert advice to both the customer and manufacturer. This will de-risk the trial process, provide the ability to conduct large elements of it earlier, offering an inherent Ship-Air operating capability from the day that the ship is launched.
 

Yokel

LE
F-8 had a very high landing speed, as well as very high accident rate, so I imagine it would be a nightmare landing on an Essex during bad weather.

Yet France bought it to operate from carriers that were significantly smaller than American big deck carriers. The Clemenceau class had a displacement of approximately 35 000 tonnes, how did that compare to a converted Essex?

The French jets had a number of modifications to the wings to reduce the landing speed by about 15 knots - which does not sound much until you think that the kinetic energy that has to be absorbed by the arresting system is proportional to the square of the speed.

The pilot also has more time to line up. According to this:

Following this, LTV offered the Marine Nationale a modified version of the F-8E, specifically designed to operate off French carriers with a lower landing speed.. This version was designated F-8E(FN), standing for French Navy.

The reduction of landing speed was made possible through several modifications. The leading edge slats were split lengthwise, which increased their drooping angle to 44°. Flap and aileron droop was also increased to 40°. These modifications substantially increased the camber of the wing in landing configuration, generating more lift and therefore lowering stall speed. A blown flaps system (known as BLC – Boundary Layer Control) was also use. This used air taken from the engine's compressor and ejected it through adjustable vents located over the flaps and ailerons. The air flow progressively increased as flaps were lowered. The angle of the variable wing was also reduced to 5° in place of the 7° of previous Crusader models. (Some sources claim the wing's angle was increased from 5°to 7°, but it was indeed a reduction from 7° to 5°). Also, the surface of the horizontal tailplane was increased to give better control at low speeds.

This set of modifications had already been suggested to the US Navy by LTV but the Navy was satisfied enough with the Crusader's behaviour during approach and had not modified its F-8 fleet. The modifications allowed a decrease of 15 knots in the Crusader's landing speed and made it far less touchy during landing. A few years later, most US Crusaders received a mid-life update including the modifications designed for the F-8E(FN).
 
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All this talk of small carriers makes me wonder if there's any scope for a UAV carrier, either as a lower level ship for navies that already operate carriers or as the main carrier for smaller navies.

UAVs might be propellor driven, such as the Israeli Heron or the Turkish Bayraktar TB2. So would hydraulic catapults be adequate for them?
Swarm tactics when used for attacks, a sufficiently developed AI system to handle the landings, with the ship defended by VLS-launched SAMs and CIWS cannon.
A high degree of automation to keep crew numbers down, this might especially be achieved if some of the UAVs were the likes of HAROP, which come in a container and apparently need little work before launch.

Could all of this even be put together as a kit, much as Atlantic Conveyor was and loaded onto a suitable merchant ship as required? Such a vessel could carry possibly hundreds of UAVs.

Indeed, could conventional carriers benefit from having part of their air wing comprised of UAVs of the types mentioned above?


 
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Yokel

LE
That sort of leads to another thread. Turkey intended to purchase the F-35B (until Erdogan upset the US) and was considering the purchase of AV-8B in the interim. Now that they have upset their only possible source of V/STOL aircraft, they have three options for their carrier/LHD Anadolu:

1. Operate her purely as an LHD.
2. Add UAVs/UCAVs/RPVs (whatever we call them today) to her helicopters.
3. Try to operate a homegrown jet - STOBAR perhaps? At 24 000 tonnes the Anadolu is on the small side for safe carrier landings, even if she was given an angled deck.

Studies being carried out as to whether HURJET could be adapted to be carrier launched-landed



Carrier design lesson 101 - build them as large as possible.
 

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