Conversion of V/STOL aircraft-carriers for CAT/STOBAR operations ?

F.L. said:
Given that the F-35B is the only VTOL aircraft on the market and that the Harrier is no longer in production and none are on the second-hand market.
Certain countries do not have the authorisation of the US government to acquire F-35Bs. The aim of this thread is to consider whether they could convert their carriers to operate aircraft available on the market : Rafale M, MiG-29K, perhaps in a short future Sea Gripen...
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If they don't have US Government authorisation for F-35B, then they're not going to have US authorisation for Sea Gripen, which makes use of an American engine, and perhaps more importantly, does not exist.

It should also be pointed out that said countries brough Harrier in the first place because it enabled them to use cheap ships, with vastly less expensive training than that required for CATOBAR operations. The cost factor is still important, and said countries are more likely to let their carrier capability atrophy into nothing (especially given said capabilities are not necessary for countries like Turkey or Thailand).
 
Tejas is dead. The INS has plans for a new twin engined carrier aircraft currently referred to as TEDBF with a prototype scheduled to fly in 2026.
en.m.wikipedia.org

HAL TEDBF - Wikipedia

en.m.wikipedia.org en.m.wikipedia.org

Meanwhile they have opted for an interim aircraft in Rafale with a recent order for 26.
www.dassault-aviation.com

India selects the Navy Rafale - Press kits

The Indian Government announced the selection of the Navy Rafale to equip the Indian Navy with a latest-generation fighter. © Dassault Aviation - C. Cosmao
www.dassault-aviation.com www.dassault-aviation.com

Sea Gripen may as well be dead. AIUI Saab needed a large financial input to move the project forward. Only India and Brazil ever expressed an interest in it. Now one avenue has closed, leaving Brazil. Brazil is a country with big ambitions but not the wherewithal to deliver. Its plans have included a 50,000 tonne carrier since before 2010 with Sea Gripen proposed to equip it. So far nothing.
 
A Tentative Fleet Plan said:
If they don't have US Government authorisation for F-35B, then they're not going to have US authorisation for Sea Gripen, which makes use of an American engine, and perhaps more importantly, does not exist.
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Yes, but I'd point out that in the case of Thailand, the Americans have already allowed them to buy Gripens, but have refused permission to buy F-35s.
Brazil has also bought Gripens.
For Turkey, it can use its Kızılelma drone in CATOBAR configuration.
 
Scott Kenny said:
Right, could have/should have deleted the "VSTOL" out of that statement.

With the baby carriers, we're talking about 20-30 aircraft. (Yes, I know spotting factors complicate things, but saying 20-30 is enough for rough ballpark work)

So the air wing looks like:
3x AEW birds (fixed wing or rotary wing),​
8-10x fighters,​
6-8x ASW helicopters.​
Maybe 1-2x tankers,​
definitely 2x COD types (if those are different from the tankers).​

Air wing of about 25, could be as low as 19.

Question becomes, what fighters are available to fly from these carriers? Legacy Hornet is out of production, Super Bug is on the way out. MiG29K, but can you trust Russia? Rafale M? Anything else?
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Ok, but this doesn't or wouldn't fit on a Chackri Naruebet or HMS Ocean, even with a lot of conversion.
Naruebet is too small for 18-25 aircraft

The former HMs Ocean (NPMAtlantico) too...the Harrier was small....the other fighters are bigger, even a hypothetical Sea Gripen. The elevators have to be changed and everything else would be so expensive that it would be worth it to build a new hull.

There is also an item that may be impassable depending on the ship. For example, the Colossus class only had 424 tons of naval aviation fuel, an Invincible Class had 900 tons, I don't know how many tons of naval aviation fuel the NPM Atlantico has. It is impossible to think about a ship without thinking about an airplane and vice versa....for smaller navies, I don't believe it is critical that airplanes are in production. It is common for these to use second-hand models. The São Paulo Aircraft Carrier, for example, was designed to operate the A-4M Skyhawk with the Elta 2032 and the refurbished S-2T Turbo Trackers, complemented by H-225M helicopters.
 
Ok, but this doesn't or wouldn't fit on a Chackri Naruebet or HMS Ocean, even with a lot of conversion.
Naruebet is too small for 18-25 aircraft

The former HMs Ocean (NPMAtlantico) too...the Harrier was small....the other fighters are bigger, even a hypothetical Sea Gripen. The elevators have to be changed and everything else would be so expensive that it would be worth it to build a new hull.

To be able to convert a STOVL ship, it would have to be a model over 30 thousand tons to try to fit the 18 to 25 aircraft of the 3 types.... this makes even models like the BPE Juan Carlos small in a hypothetical conversion. Only the Cavour and the second-hand LHD Tarawa would be left...much bigger...

This is why my thesis for small countries lies in learning the concepts of the British RFA in terms of mobilization, Arapaho and Scads, implementing improvements that are now technologically viable

1) Design ships with merchant specifications (lower cost), but with dual functions, civil and military
2) Plan for pre-availability of kits, Ski Jump, braking cables, fuel tanks
3) Acquire 1 hull to develop doctrine in your navy
4) sponsor the sale of other hulls to national merchant shipowners

Those who have very little, the war attrition rate does not allow them to have a single aerodrome ship. it is better to disperse the aerodrome ships

bpe-270-metros-f6.png
 
carvalho2008 said:
...
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I like your concept of converting the Juan Carlos, which would be a good fit for the TCG Anadolu, which has the same design as the Juan, and is now without fixed wing air group following the S-400 affair and the US purchase ban on the F-35.
On the other hand, your design requires a complete rebuild of the ship.
 
F.L. said:
I like your concept of converting the Juan Carlos, which would be a good fit for the TCG Anadolu, which has the same design as the Juan, and is now without fixed wing air group following the S-400 affair and the US purchase ban on the F-35.
On the other hand, your design requires a complete rebuild of the ship.
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Thanks! But see that the one I designed is a much larger model, weighing about 45 thousand tons. A truly multifunctional amphibious and stobar ship of 270 meters.

I believe this is what the British should have done when they deviated to the 65,000 ton CVFs.

The initial ideas were to take advantage of Ocean's successful experience of low civil cost and implement a new 40-45 thousand ton model. The only difference is the use of braking devices.
 
carvalho2008 said:
But see that the one I designed is a much larger model, weighing about 45 thousand tons. A truly multifunctional amphibious and stobar ship of 270 meters.
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When I compare the Anadolu (232m) to my STOBAR version of the Chakri Naruebet (182m), I think it would be possible to convert the Anadolu and have an angled deck long enough to land jets.
On the Chakri STOBAR, it was about 10m short of being able to land jets safely (145m).
 
F.L. said:
When I compare the Anadolu (232m) to my STOBAR version of the Chakri Naruebet (182m), I think it would be possible to convert the Anadolu and have an angled deck long enough to land jets.
On the Chakri STOBAR, it was about 10m short of being able to land jets safely (145m).
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For a classic Stobar takeoff operation, the reference distances are 80 meters run in air defense configuration and 180 meters run in heavy attack configuration.

This is why in my conjecture models of a mixed military and merchant plant, with dual use, I cannot do without using the SATS concept as an aid to ski jumping.
20091228162620.jpg
bpe-270-metros-30012021b.png

6414614927_85bf9ee8cf_o.jpg
 
carvalho2008 said:
Ok, but this doesn't or wouldn't fit on a Chackri Naruebet or HMS Ocean, even with a lot of conversion.
Naruebet is too small for 18-25 aircraft

The former HMs Ocean (NPMAtlantico) too...the Harrier was small....the other fighters are bigger, even a hypothetical Sea Gripen. The elevators have to be changed and everything else would be so expensive that it would be worth it to build a new hull.
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Yes, at that point you either fly pure helicopters or build a new ship large enough to be useful.

Though I guess tilt rotors and compound helicopters could do interesting things...


carvalho2008 said:
There is also an item that may be impassable depending on the ship. For example, the Colossus class only had 424 tons of naval aviation fuel, an Invincible Class had 900 tons, I don't know how many tons of naval aviation fuel the NPM Atlantico has.
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The trick there is to have the ship's powerplant burn JP5, even if the ship's powerplant is steam.


carvalho2008 said:
It is impossible to think about a ship without thinking about an airplane and vice versa....for smaller navies, I don't believe it is critical that airplanes are in production. It is common for these to use second-hand models. The São Paulo Aircraft Carrier, for example, was designed to operate the A-4M Skyhawk with the Elta 2032 and the refurbished S-2T Turbo Trackers, complemented by H-225M helicopters.
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Thing is, these days the Skyhawks are 70 years old, and running out of fatigue life.

So now we're looking at armed T-45s or maybe a navalized M346/Yak130 for the smallest carriers.
 
Scott Kenny said:
So now we're looking at armed T-45s or maybe a navalized M-346/Yak-130 for the smallest carriers.
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I was thinking about that too.
This seems to me to be a good solution for the kind of mission these "mini aircraft carriers" would be designed for. Because it's obvious that they are not and would not be designed to operate hordes of aircraft in "battle of midway" style.
If it is one day put into service on aircraft carriers, the JL-9G also seems to me to be a very good solution.
And a possible naval variant of the FA-50 Golden Eagle.
Sans titre.png proxy-image.jpg
 
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F.L. said:
I was thinking about that too.
This seems to me to be a good solution for the kind of mission these "mini aircraft carriers" would be designed for. Because it's obvious that they are not and would not be designed to operate hordes of aircraft in "battle of midway" style.
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Yes, these baby carriers are basically just running 24/7 AEW, 2-plane CAP, and ASW. Not launching strikes or anything big.

Air group of 3x AEW, 8x fighters, ~6x ASW helicopters, and 2x COD as the minimum.
 
carvalho2008 said:
Takeoff in less than 200 meters and at just 18 knots without using a catapult.
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It seems that Turbo Trackers still have a few good days ahead of them, but I have my doubts about using them with a skijump.
What's more, on this type of mini-carrier, helicopters seem better suited to ASW missions. (A bit like the Soviet Kiev and Kuznetsov class aircraft carriers.)
It has to be said that on the Colossus-Majestic class aircraft carriers, the Trackers were barely small enough. Particularly on the HMAS Melbourne, on landing the margin with the island was really small. (edited : probably wrong)
Ultimately, an aircraft carrier such as the Chakri or PdA STOBAR would have similar capacity to the Melbourne, Vikrant or 25 de Mayo.
 
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In the 60s Melbourne's aerial group was sometimes limited to 4 Sea Venoms, 6 Gannets & 10 Wessex.
But more commonly, 8 Sea Venoms, 16 Gannets & 2 Sycamore for SAR.
And the Invincible-class carrier's air group grew from the original 5 Sea Harriers and 9 Sea Kings to nine Harrier and twelve helicopters (usually all Sea King ASW &/or AEW) after various refits.

I think that this style of converted carrier could have an air wing of :

For attack missions :
- 6 fighters,
- 8 attack heicopters (Cobra, Ka-52, Tiger...)
- 4 ASW helicopter,
- 2 early warning helicopter (Ka-31, Sea King, EH-101A...),
- 2 multi-role helicopters.

For anti-submarine escort missons :
- 8 fighters,
- 8 ASW helicopter,
- 4 early warning helicopter.
- 2 multi-role helicopters.

For Air superiority missions :
- 12 fighters,
- 6 early warning helos,
- 4 multi-role helicopters.

A total of 22 aircrafts.

It remains to be seen whether all this will fit on the different carriers possible after conversion. (Chakri, Atlantico, Anadolu...)
 
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F.L. said:
It seems that Turbo Trackers still have a few good days ahead of them, but I have my doubts about using them with a skijump.
What's more, on this type of mini-carrier, helicopters seem better suited to ASW missions. (A bit like the Soviet Kiev and Kuznetsov class aircraft carriers.)
It has to be said that on the Colossus-Majestic class aircraft carriers, the Trackers were barely small enough. Particularly on the HMAS Melbourne, on landing the margin with the island was really small, 1 meters if I remember correctly.
Ultimately, an aircraft carrier such as the Chakri or PdA STOBAR would have similar capacity to the Melbourne, Vikrant or 25 de Mayo.
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What... like this?

TrackerScaleMelbourneForum.jpg


Tracker on final approach on Melbourne with Tracker ready to catapult:

Tracker Final Approach on Melbourne.jpg


size comparison:

enterprise & melbourne.jpg


BigE-LittleMCover-Navy_News-May-5-1.jpg


HMAS Melbourne FAC 1969.jpg
 
F.L. said:
Particularly on the HMAS Melbourne, on landing the margin with the island was really small, 1 meters if I remember correctly.
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BlackBat242 said:
What... like this ?
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Unfortunately, I can't remember where I read that, so it remains to be confirmed. But looking at your schematic, I don't see how it could be, so I'm certainly wrong.
 
Scott Kenny said:
20-30ft above the waterline is usually plenty of space. And that leaves the flight deck about 50-60ft above the waterline.
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Which is why it couldn’t be done in the Colossus/Majestic class like Melbourne. There were only two deck levels between the waterline and the hangar floor so not enough for a side lift. A side lift for the Victorious rebuild was rejected for the same reason. And the one fitted to Ark Royal only accessed the upper hangar due to lack of freeboard at the lower level.

As designed, the Centaur class had most of the height of an extra deck level between the waterline and hangar floor. That was enough to allow Hermes to have a side lift.
 
carvalho2008 said:
This model is only 212 meters long.

Even so, its upper landing deck is much longer than the deck of the Clemenceau class.

Another point, in the hypothesis of a lower deck takeoff with Ski jump, you solve the problem of landing and takeoff operations at the same time

It is necessary to study how to resolve the blast on the lower deck.

I reiterate that an auxiliary catapult based on the SATS CE-2 concept can be organically implemented in the model and work to assist the ski jump for that lower percentage of missions with aircraft at Max MTOW.

A step further than a Stobar, halfway to Catobar but with much less complexity.

20091228162632.jpg
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I've often wondered the feasibility of a combined catapult_ski-jump arrangement...

Regards
Pioneer
 
Pioneer said:
I've often wondered the feasibility of a combined catapult_ski-jump arrangement...

Regards
Pioneer
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I believe it's possible, but costs you some catapult length (or makes you start the cats farther aft). That's by having a cat that doesn't go up the ski jump, and simply stops at the start of the ski jump.

Edit: call it ~25m less catapult length, or starting the catapult 25m farther aft.
 
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helmutkohl said:
been trying to find a before and after schematic on google but couldn't.
because on first glance, it seems that the deck modification looked minimal. (no significant protrusions like on other conversions of that era)
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HMAS Sydney and HMAS Melbourne were both built to the same design until after launching. Sydney was completed to nearly the original design, and Melbourne was completed with the angle deck.

Sydney is to port, Melbourne in the port middle, with HMAS Supply middle starboard and HMAS Yarra starboard, 24 March 1966.
Note the longer elevators, as well as the flight deck differences. Those only added a small amount to her displacement, however... showing how little steel was actually added.

HMAS Sydney, Melbourne, Supply &Yarra.jpg


HMAS Sydney [ex-Terrible] (Majestic Class)
Displacement 15,740 tons (19,550 tons full)
Hangar = 275 x 52 x 17.5ft with a 57ft extension aft of the aft lift
Lifts = 45ft long x 34ft wide (fwd lift) & 45ft long x 34ft wide (aft lift) both with a 15,000lb capacity
One BH-5 Mitchell-Brown hydraulic catapult that propelled 28,000 lb to 75 knots.
Arresting gear was 8 wires @ 20,000lb capacity each.

HMAS Melbourne [ex-Majestic] (Majestic Class)
Displacement 15,740 tons (20,000 tons full)
Hangar = 275 x 52 x 17.5ft with a 53ft extension aft of the aft lift
Lifts = 54ft long x 34ft wide (fwd lift) & 54ft long x 34ft wide (aft lift) both with a 24,000lb capacity.
One Mitchell-Brown steam catapult that propelled 40,000 lb to 78 knots or 30,000 lb to 101 knots.
In 1971 her catapult was lengthened by building a bridle catcher onto the forward end of the flight deck. This increased the overall length from 151' to 160', and the stroke length from 104' to 112'.
Arresting gear was 6 wires @ 30,000lb @ 60 knots capacity each, reduced to 5 in 1971 as part of strengthening the aft flight deck.

Melbourne & Sydney early 1960s.jpg
 
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Scott Kenny said:
I'm still amazed at how long it took people to put elevators at the edges of the flight deck, instead of in the middle of the flight deck.
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zen said:
Putting big holes too close to the waterline is not advisable.
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Scott Kenny said:
20-30ft above the waterline is usually plenty of space. And that leaves the flight deck about 50-60ft above the waterline.
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EwenS said:
Which is why it couldn’t be done in the Colossus/Majestic class like Melbourne. There were only two deck levels between the waterline and the hangar floor so not enough for a side lift. A side lift for the Victorious rebuild was rejected for the same reason. And the one fitted to Ark Royal only accessed the upper hangar due to lack of freeboard at the lower level.

As designed, the Centaur class had most of the height of an extra deck level between the waterline and hangar floor. That was enough to allow Hermes to have a side lift.
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The port-side lift on Hermes had 23' 6" freeboard (officially 24' but that was at the Centaur class' original displacement) at the hangar deck opening - this was the absolute minimum the RN considered acceptable for a deck-edge aircraft lift.*

Victorious had only 14'.
The upper hangar on Indomitable had 23' 6", while the upper hangar of the Audacious class (as designed) had 30', with the lower hangar at 10'.

The proposed "1952 carrier" had 24' freeboard, and was planned for deck-edge lifts.


I have a set of USN plans for CV-5 Yorktown, and they show 24' 5" freeboard... so they could have been fitted with a deck-edge aircraft lift.

The Essex & Midway classes had 25' freeboard**, the supercarriers are more like 30'.


The French Clemenceau and Foch had 24' freeboard.


The Italian Cavour has 18' freeboard for her side lift, but reportedly use is restricted to light or moderate sea states only (the Med is normally calmer than the Atlantic, fortunately).


* Here is a comment from a former crewmember of Hermes (hermes82 on Navweaps):
Hermes fwd lift was a deck edge side lift.
It was pretty dangerous in choppy weather nearly got washed over the side on at least 2 occasions, really thought I was a goner.
My mate was the lift driver at flight deck level he got submerged by one wave whilst we stuck a cab on it, you can imagine how wet we were.
The lift acted like a knife blade through the water when it was at hangar level damaged the cab as well.

** Midway completely lost her starboard lift (aft of the island) in 1964 during an underway replenishment due to wave action: https://www.midway.org/blog/aircraft-elevator-story/
 
Pioneer said:
I've often wondered the feasibility of a combined catapult_ski-jump arrangement...

Regards
Pioneer
Click to expand...
I think it is completely possible to use an auxiliary catapult on a stobar aircraft carrier.

In reality, my thesis is that of specific projects for merchant ships that can predict in advance their conversion if necessary. This undoubtedly involves a specific doctrine of air force modularity and training, but there is no need to doubt this, given that the air forces train operations on asphalt highways. A ship of 30 to 45 thousand tons will always have much more structure to offer, especially if it is already pre-designed for this possibility.

An auxiliary catapult in the style of the CE-2, using 2 F-414 turbines, could be installed below the ski jump gap. Since the system uses a complex steel cable spool, I believe it could follow the curvature of the ramp. Even if it cannot, this would be secondary, as the function of the auxiliary catapult is only to eliminate the percentage loss of combat load of a fighter in attack weight configuration at maximum take off. In an air defense configuration, the ski jump already provides 100% of the necessary power.

bpe-270-metros-30012021b.png
 
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