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

@F.L. The angled deck is too short for any modern jet aircraft. You need to factor in the following minimum dimensions, which are driven by the basic physics of the approach slope / ramp safety height and energy required to stop a 10-15t aircraft:

Ramp to target wire (HMAS Melbourne): 45m / 150ft
Wire to wire: 10m / 30ft
Wire runout (Essex class): 70m / 230ft
Aircraft length (+space to turnaround): 20m / 60ft
Total angled deck length: 145m / 480ft

That’s the bare minimum, same as HMAS Melbourne, with no safety margins. The Essex class angled deck was 520ft (158m) and the Clemenceau was 540ft (165m). You can use my SAC-185 drawing which is 510ft (155m).

Seems like your angled deck is only ~125m / 410ft so would need to be lengthened by at least 20m / 70ft. Also unlikely that the forward lift could be moved… I would keep it where it is.

Why not try with Principe de Asturias first and see if that is possible? PdA was decommissioned after only 25 years so in theory could have been bought by another navy and upgraded.
 
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F.L. said:
This idea came to me when I read the story of HTMS Chakri Naruebet. Since 2006, it has had no air group following the withdrawal of the Thai Navy's AV-8S Harriers and the failure to purchase AV-8B or Sea Harriers.
Would it be possible to convert an S/VTOL aircraft carrier for STOBAR operations with aircraft such as the Sea Gripen, Rafale M or Kızılelma for countries who are not able to purchase F-35B ?
Given that some vessels of this type already have a skijump (Chakri, Anadolu, Canberra), the main modification would be to add arresting gear.
Given that some of these ships are designed to operate few aircraft (6 on Chakri), the bolter is less a problem than on the old straight-deck aircraft carriers.
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Master F.L.,

I have carried out several researches in recent years on a similar subject that could be useful in your proposition.

My thesis is the development of a doctrine that is 2 or 3 steps away from the Arapaho and Scads concept.

It consists of you, following the example of the RFA, in which it designs special requirements for merchant ships that can be called up for the war effort, creating an auxiliary merchant plant with dual military and merchant functions with pre-availability kits.

One of the aspects among these kits consists of you redesigning the SATS system used in Chu Lai.

Note that a centrifugal catapult powered by one or two F-414 engines can provide the necessary complement of launching power if added to a ski jump. The structure of a ski jump is very simple and so is this type of catapult. It would work in a combined or complementary way depending on the maximum weight of the plane. It is worth remembering that in 80% of operations the plane takes off lightly and even the catapult would be dispensable when the plane was configured for air defense.

The next kit would be the Arresting gears stop cables. The sats system also had this equipment. Obviously all of this would have to be redesigned in order to make sense on a naval platform between 212 meters and 260 meters of smooth deck. But we must remember that the Sats system was designed for improvised ground operations, with zero relative wind, no ski jump, and obstacles of 50 feet at the end of the runway, whereas on a ship the plane would be 40-50 meters high.

Well, include this concept and you would be able to achieve these goals, even in a tiny Chacri naruebet. The limits are actually linked to the hangar capacity or onboard naval aircraft fuel. Small air groups do not require much deck movement and there is no way to congest it with just 8 to 12 units...

planta-mercante-9-copia.jpg
 
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Temeraire said:
Probably not the Chakri Naruebet, due to it’s small size the arrestor engines most likely wouldn’t fit and they’d have to make so many adjustments it would be more economical to purposely build a STOBAR ship.
The other ship you show NAM Atlântico (formerly HMS Ocean) is a definite no she cannot even operate STOVL aircraft with any real capability as she lacks a ski jump. Her aft lift is also in the way of any arrestor gear.
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In my drawings, I usually allocate stop cable kits on merchant ships on the sides.

On a common aircraft carrier, you use a deck floor for the arresting gear engine room. however, it would be possible for equipment similar to the specially designed SATS to be installed on the sides, on the edges of the ship's bow, as sidewalls. The sober and ai pulleys cover the deck at the landing contact point.
mac-merchant-aircraft-carrier-a5.png
 
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F.L. said:
And Anadalu with Kızılelma ? The NAM Atlantico also will be converted for drones operations.
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I believe that Kizileuma is possible in both, but Atlantico would need renovation for ski jumping.

The kizileuma is STOL with just 10 meters wingspan and 14.7 meters long.
 
ok i guess no one brought it up yet..
but what would the incentive for navies, on why they should convert their VSTOL carrier for STOBAR operations?
aside from the Queen Elizabeth, most VSTOL carriers are pretty small.
you're swapping out, say 10 harriers or F-35Bs for 10 Rafales/Gripens/etc, plus an assortment of helicopters.

What would this accomplish in terms of tasks? Is there any advantage in having this major conversion, just so you can switch from 35Bs to Rafales? Most of the STOBAR carriers probably cant handle larger AEW aircraft either.

Most STOVL carrier air wings are not really intended for the same tasks as a super carrier battle groups.
 
The Alizes airframes were milked to the last drop. Crews complained the cockpit wasn't even sealed properly from rain.
 
helmutkohl said:
But what would the incentive for navies, on why they should convert their VSTOL carrier for STOBAR operations ?
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The aim of this conversion would be to enable countries with S/VTOL aircraft carriers but unable to buy F-35Bs (Thailand, Turkey) to reuse their ships anyway.
With the forthcoming disappearance of the Harriers, the problem of the F-35B being the only aircraft of this type on the market arises.
 
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H_K said:
Why not try with Principe de Asturias first and see if that is possible ?
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What do you mean by that ? :)
I've used the PdA as the basis for my 3d, because it's Chakri sistership.
H_K said:
PdA was decommissioned after only 25 years so in theory could have been bought by another navy and upgraded.
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It's true that it still hurts my heart to think that this ship has been scrapped. I would have liked to see it in Argentina or Chile...
 
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F.L. said:
The aim of this conversion would be to enable countries with S/VTOL aircraft carriers but unable to buy F-35Bs (Thailand, Turkey) to reuse their ships anyway.
With the forthcoming disappearance of the Harriers, the problem of the F-35B being the only aircraft of this type on the market arises.
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There's not too many STOBAR options. Sea Gripen is probably highly unlikely. The demand for the regular Gripen is already low as is.
Thailand would probably be limited to the MiG-29K, Rafale M and the Super Hornet. I wonder if the super hornet would be too big for these small STOVL carriers. Also the elevators/

Turkey has probably just the Super Hornet. cant imagine a NATO country going for a the MiG-29K, and France likely wont sell the Rafale to Turkey.

There is the KF-21N floating around but I think that is also unlikely.
 
Once Super Hornet is out of production it just leaves the Rafale M and F-35C.
Naval aviation is a niche and today is a very narrow niche - the only two CTOL carrier builders today are the USA and China and so any options will come from those nations.
KF-21N might become a reality but it will be expensive given SK is unlikely to have more than one carrier so the amortisation costs will be high.

Likely as not the UCAV will replace STOVL within 30-40 years.
 
helmutkohl said:
Sea Gripen is probably highly unlikely.
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Why ? It has been proposed to India and Brazil. I don't see why it can't be reactivated for another country on request.
Sea-Gripen-2-NAe-São-Paulo.jpg sea gripen flier.jpg
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Hood said:
Once Super Hornet is out of production it just leaves the Rafale M and F-35C.
Naval aviation is a niche and today is a very narrow niche - the only two CTOL carrier builders today are the USA and China and so any options will come from those nations.
KF-21N might become a reality but it will be expensive given SK is unlikely to have more than one carrier so the amortisation costs will be high.

Likely as not the UCAV will replace STOVL within 30-40 years.
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Today , Mig29k, F18SH, Rafale, Tejas M, S2T Turbo Tracker, FC-31

Possible : Sea Gripen, Kizileuma, Hurjet, FC-31, JL-9G
 
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helmutkohl said:
Because it would take time and money to do this, something which a country ordering only 10 units of, would unlikely do.
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Given that such a conversion mainly concerns countries that cannot purchase F-35s, the Rafale M is one of the only options, along with the MiG-29K.
 
carvalho2008 said:
JL-9G
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The JL-9G would be realy interesting, but I don't think it's carrier-qualified, only for simulated carrier landing.
A carrier-landing trainer variant was revealed by Chinese state media in 2011. Designated the JL-9G, it has strengthened undercarriage, enlarged wing and diverterless supersonic inlets, but has proved to be unsuitable for arrested landings and is limited to land-based operations.
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F.L. said:
The JL-9G would be interesting, but I don't think it's carrier-qualified, only for simulated carrier landing.
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militaire-jl-9a-00016.jpg


They were developing the WP-14 which would be 20% more powerful than the WP-13. It seems like they haven't given up....long live the Mig-21.....
 
at the end of the day, you'd want an aircraft that has a substantial customer base, because smaller navies are unlikely to share the risk and fund the development of something that is not used by a larger military.
Hence without India buying large numbers of Sea Gripens, I see it as unlikely to go anywhere.

the future of STOBAR operations will be MiG-29K, Rafale M, Super Hornet, F-35B, J-15, J-35, and whatever India decides on.
I personally think they should just have stuck with the Naval Tejas and Rafale.

the JL-9 is supposed to be a carrier capable trainer. should be small enough to operate on smaller stovl carriers
www.flightglobal.com

New naval JL-9 trainer takes flight in China

A new variant of the AVIC Guizhou JL-9 Mountain Eagle advanced jet trainer modified to train naval pilots has conducted its maiden flight.
www.flightglobal.com www.flightglobal.com

but at the end of the day, I think for stovl carrier operators.. upcoming UCAVs like kizilema might be the best option.
 
F.L. said:
No, the Tejas M is not finished being developed, the FC-31 is not yet in service and is not being offered for export.
The F-18SH does not exist. There are no Hornet variants with this name.
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Ok, sorry...Super Hornet....

Why the concern? if the Tejas M is not yet finished, or Jl-9G, if you trying to exemplify a Sea Gripen or a Super Tucano....

The conversion of a ship to Stobar until it enters into operation would take 5 to 10 years....enough time for the completion of the proposed air assets...including an Fc-31/J35....
 
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Archibald said:
The Alizes airframes were milked to the last drop. Crews complained the cockpit wasn't even sealed properly from rain.
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The S2T Turbo Trackers that Brazil was renovating were almost ready when the contract was canceled when retired São Paulo

This plane could be used for COD or AEW if so configured. They could take off from the old Minas Gerais Aircraft Carrier without using a catapult. With a ski jump it would be easy. It is a STOL par excellence
 
H_K said:
Total angled deck length: 145m / 480ft
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I think it's possible. Already, by extending the deck aft, it's possible to have a 140m angled deck. I'm going to see if it's possible to extend it by 5/6m at the front.
 
F.L. said:
What do you mean by that ? I've used the PdA as the basis for my 3d, because it's Chakri sistership.
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Not really. Chakri is a mini-PdA, 10% shorter, 10% narrower and 30% less displacement… overall a much smaller ship.

That’s why I was suggesting that PdA might be a better starting point than Chakri as the larger size will help with fitting an angle deck.

th_principe_de_asturias_and_chakri_naruebet.jpg
 
@F.L. Here’s another small carrier from my library, the French PH75 (18,500t).

This shows what a small aviation optimized design might look like, with capacity for ~14-16 fighters and a few helicopters. I added a ski jump and angle deck but otherwise kept things mostly unchanged (though in real life it would have diesel propulsion instead of nuclear).

Also including a comparison with a Colossus class carrier and the PdA-sized “SAC-185” what-if. They are all quite comparable.

PH75_Stobar_Rafale.png


BSAC_185_vs_PH75_vs_Colossus.png
 
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F.L. said:
Is your design derived from the PH-75 nuclear helicopter carrier project ?
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Yes that’s right.

I feel like the benefit of using PH75 as a starting point is that this was a “real” angle deck design with STOL capability so the only question becomes how to add arrestor wires for STOBAR aircraft (with a slightly longer ~155m angle deck), and secondarily how to replace nuclear+steam turbines with diesels.

This could have been a good Colossus replacement in the 80s with F/A-18s (Australia) or in the 2000s with Rafales, Mig-29s or Sea Gripen (Brazil). Or alternatively it could start as a Harrier carrier (eg. for Thailand) with future expansion ability to STOBAR.
 
In November 1973 a two-seat Harrier prototype tested on Clemenceau and also on the 12 000 tons Jeanne d'Arc LPH.

Also, at the very beginning (1970) PH75 wasn't nuclear: it was to use the machinery of F67 frigates : the Tourville class
en.wikipedia.org

Tourville-class frigate - Wikipedia

en.wikipedia.org en.wikipedia.org

In French service it was to replace good old Arromanches which had find itself a role of "Swiss knife" in the French Navy: after Foch and Clem IOC in 1964, it still had a decade of life left, and it used it very efficiently.
Arromanches played the roles (altogether) of
- LPH
-training ship (naval Fouga Magister: Zéphyr)
-ASW carrier (helicopters of course, BUT also Alizés - they could operate out of it)
- crisis & hospital ship
- commando carrier.
You can guess why and how PH75 was designed as a "Swiss knife" ship along the same way as Arromanches last life.
 
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I believe that for a small aircraft carrier with an air wing of between 12 and 18 units, the best layout would be this with a negative angle. I have already measured this in my drawings and you can see that the size of the landing deck is quite long. This model, for example, is much larger than the Clemenceau class.
 
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carvalho2008 said:
I believe that for a small aircraft carrier with an air wing of between 12 and 18 units, the best layout would be this with a negative angle.
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I love the elegance of the reverse angled deck but never quite figured out how the aircraft flow would work during recovery operations, as each aircraft needs time to turn around and clear the runway. Plus the forward deck park is minuscule.

… I suspect it would only work in real-life with a low sortie rate with only groups of 2-4 aircraft landing at any one time. That would be fine for CAP and long ASW patrols but would not work for anti-ship strikes or anything requiring a half-squadron (or more) to operate together for mutual support.
 
going back on topic, this should be nearly all the vstol carriers for consideration although its missing the Thai carrier

Among these: The Japanese, Italian, US, and Australian ships should have no problem in getting F-35Bs. Turkey could be possible too, a return to the F-35 program in exchange for some other concession. I dont think the US would object to the 35Bs being sold to France either, if the French government and industry decide in the unlikely event they want to import American.

Egypt and Brazil may not be F-35B candidates.. and definitely not China.
the Algerian ship is too small.
So in their cases, if they wanted to do a conversion to STOBAR, the Rafale M could be a good choice.

China's case, they would use the J-15, which I think is too large for these ships, even if they converted it. And they probably wouldn't do it either as they already have full sized carriers.

611H7IYJcKL._AC_UF1000,1000_QL80_.jpg
 
H_K said:
I love the elegance of the reverse angled deck but never quite figured out how the aircraft flow would work during recovery operations, as each aircraft needs time to turn around and clear the runway. Plus the forward deck park is minuscule.

… I suspect it would only work in real-life with a low sortie rate with only groups of 2-4 aircraft landing at any one time. That would be fine for CAP and long ASW patrols but would not work for anti-ship strikes or anything requiring a half-squadron (or more) to operate together for mutual support.
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Colossus class, Invencible, SCS Zumwalt, Foch, QE

You can see how flyght deck Zumwalt is much bigger than Foch with reverse angled deck

With only 12 to 18 planes, it is very difficult to congest the deck. Although capable of carrying out projection attacks, its role is focused on air and fleet defense. The volume of air operations is much smaller, but within what small countries need to enable their navies to leave for the ocean
vss-zumwalt-double-deck-aircraft-carrier-c.jpg
 
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carvalho2008 said:
Colossus class, Invencible, SCS Zumwalt, Foch, QE

You can see how flyght deck Zumwalt is much bigger than Foch with reverse angled deck

With only 12 to 18 planes, it is very difficult to congest the deck. Although capable of carrying out projection attacks, its role is focused on air and fleet defense. The volume of air operations is much smaller, but within what small countries need to enable their navies to leave for the ocean
(img deleted for space)
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I gotta admit, the reverse angled deck is growing on me. It's a quite elegant solution to the packaging problem and lets you keep the Flight Ops tower well aft for best views.

The challenge is that you absolutely cannot conduct catapult launch and arrested recovery at the same time. So in a navy like the USN or PLAN, they're probably not going to want to deal with the different traffic pattern around the small carriers versus large carriers.

Smaller navies, the ones where this is their first "real" carrier, not an LHA, probably won't care.


==========
PS: Don't forget to add the crash barrier net for recovering planes than have had their tailhooks fail.
 
Scott Kenny said:
I gotta admit, the reverse angled deck is growing on me. It's a quite elegant solution to the packaging problem and lets you keep the Flight Ops tower well aft for best views.

The challenge is that you absolutely cannot conduct catapult launch and arrested recovery at the same time. So in a navy like the USN or PLAN, they're probably not going to want to deal with the different traffic pattern around the small carriers versus large carriers.

Smaller navies, the ones where this is their first "real" carrier, not an LHA, probably won't care.


==========
PS: Don't forget to add the crash barrier net for recovering planes than have had their tailhooks fail.
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yes....
 

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