Sea Control Ship (SCS) and VSTOL Support Ship (VSS)

[H_K]

The flight-deck layout for VSS No.3 as described is probably the one shown in the Naval Engineers Journal in 1977, the number of catapults, arrestor wires and elevator locations all match.

Thanks, reading that Naval Engineers Journal article again I suspect that the 35,000 ton “minimum length” design shown (813ft flight deck, 572ft angled deck, ~30 aircraft) may be very similar to VSS No. 2.

I’ll draw it up and try an A-7 max spot to see what kind of deck multiple I get…

 

[H_K]

OK here are the 2 VSS designs with a maximum density spotting of A-7Es. The deck multiple is 45 A-7s for the slightly smaller VSS 3 (reverse angle deck) and 54 A-7s for what I believe is VSS 2 with a traditional angle deck. This is close to the 48 A-7s quoted for VSS 3 and to the 54 A-7s I get for Clemenceau.

This would seem to confirm that there is no way the 72 A-7s quoted for VSS 2 is correct.

By the way, 54 A-7s @ 75-80% operational capacity equals 40-43 A-7s, or 34-36 F/A-18s in real life. Which aligns pretty well with the quoted "30 aircraft" in Naval Engineers Journal.

 

[TomS]

OK here are the 2 VSS designs with a maximum density spotting of A-7Es. The deck multiple is 45 A-7s for the slightly smaller VSS III (reverse angle deck) and 54 A-7s for what I believe is VSS II with a traditional angle deck. This is close to the 48 A-7s quoted for VSS III and to the 54 A-7s I get for Clemenceau.

This would seem to confirm that there is no way the 72 A-7s quoted for VSS II is correct.

By the way, 54 A-7s @ 75-80% operational capacity equals 40-43 A-7s, or 34-36 F/A-18s in real life. Which aligns pretty well with the quoted "30 aircraft" in Naval Engineers Journal.

This is very useful.

It also highlights an area where Friedman's work misses the mark, or at least is talking about something significantly different.

So, he talks about VSS I, VSS II, and VSS III. Based on the scant sourcing, he is probably using a NavSec history of SCS as his source.

But his VSS II and III do not match the dimensions or other specs of the VSS No 2 and VSS No 3 designs the Navy gave to Congress. For one glaring example, all three of Friedman's VSS designs are gas turbine ships while the Navy testimony above has No 2 and No 3 as steam ships. But those ships also do not match the pre-SCS steam concepts mentioned in passing by Friedman. So, clearly VSS had several iterations that did not appear in US Aircraft Carriers at all. Fascinating stuff.

 

[H_K]

Here’s a comparison of the 2 VSS designs with Clemenceau (bottom). The hangar sizes are a rough guess based on elevator positioning.

Overall I prefer the Clemenceau layout in a number of respects (deck edge elevator, more angle on the landing area and waist catapult which frees up deck parking ahead). But the VSS designs have the benefit of longer C13-0 catapults (254ft stroke) and were apparently beamier which is good for seakeeping.

Perhaps the ideal would have been a VSS 2 derivative with C13s but a more Clemenceau-like flight deck layout.

 

[Archibald]

Here’s a comparison of the 2 VSS designs with Clemenceau (bottom). The hangar sizes are a rough guess based on elevator positioning.

Overall I prefer the Clemenceau layout in a number of respects (deck edge elevator, more angle on the landing area and waist catapult which frees up deck parking ahead). But the VSS designs have the benefit of longer C13-0 catapults (254ft stroke) and were apparently beamier which is good for seakeeping.

Perhaps the ideal would have been a VSS 2 derivative with C13s but a more Clemenceau-like flight deck layout.

And this is a non nuclear CdG !

 

[H_K]

Outline specs for the V/STOL Support Ships (VSS) under study as of 1975 attached

I figured I’d try to compare the costs of SCS and VSS from this table to the cost of a conventional CV/CVN…

… is it fair to say that you could buy 3 VSS w/catapults for the price of 1 CVN??? ($445M vs. $1,367M). That sounds like a pretty good trade off, almost the same cost per ton and per aircraft.

VSS was $430-445M in 1976 dollars, SCS was $180M (both follow-on cost):

Second Supplemental Appropriations for Fiscal Year 1976

www.google.com

CVN-70 was $1,367M, also in 1976 dollars:

Fiscal Year 1977 Authorization for Military Procurement, Research and Development, and Active Duty, Selected Reserve and Civilian Personnel Strengths

www.google.com

 

[TomS]

It depends on what you're using them for .

The striking power of one CVN would exceed that of three VSS, when you look at the capabilities of the actual aircraft, the depth of magazines, etc.

OTOH, one CVN can't provide ASW cover for three convoys.

 

[zen]

One of anything isn't available all the time. Minimum for ships is normally 3 and at a pinch 2.

 

[Yellow Palace]

You can get that figure down, depending on the service required. I've seen estimates for coastal picket duties that have gone down as low as 3-for-2. Commercial shipping - including naval auxiliaries, which share a lot of operating practices with the commercial world - routinely operate at a ratio not much better than 1-for-1.

The 3-for-1 ratio really comes into consideration when you're looking at forward deployment on a sustained basis.

 

[MrTopaz]

From U.S. Aircraft Carriers: an Illustrated Design History by Norman Friedman.

This 325-ft SWATH ship was proposed by the David W Taylor Naval Ship Research and Development Center in 1980 to operate short takeoff, vertical landing (STOVL) fighters.

The caption says 325-ft SWATH ship, but this looks like a larger monohull design.

This is reaching way back in this thread, but can anyone identify the fighter in this painting? Is there any information about whether it's supposed to be the Vought Super Fly, some other specific model, or just a notional VASTOL fighter?

 

[TomS]

From U.S. Aircraft Carriers: an Illustrated Design History by Norman Friedman.

This 325-ft SWATH ship was proposed by the David W Taylor Naval Ship Research and Development Center in 1980 to operate short takeoff, vertical landing (STOVL) fighters.

The caption says 325-ft SWATH ship, but this looks like a larger monohull design.

This is reaching way back in this thread, but can anyone identify the fighter in this painting? Is there any information about whether it's supposed to be the Vought Super Fly, some other specific model, or just a notional VASTOL fighter?

Judging from the caption that usually goes with this photo, it was apparently a concept from the David Taylor Research Center. But, this makes little sense to me, since DTRC had little or no experience in aircraft design. It really does look like the Superfly (SF-121) and DTRC may well have used that as a placeholder for their VATOL carrier design.

File:428-GX-KN-31380 (24463970746).jpg - Wikimedia Commons

commons.wikimedia.org

428-GX-KN-31380: Artist Conception of the Short Takeoff and Vertical Landing (STOVL) fighter concept, developed by the David W. Taylor Naval Ship and Research and Development Center, in various stages of flight and recovery positions near the 325 foot small water plane area twin hull ship (SWATH), received February 1981. Artist is unknown. U.S. Navy Photograph now in the collections of the National Archives. Photographed from reference card only.

 

[MrTopaz]

Judging from the caption that usually goes with this photo, it was apparently a concept from the David Taylor Research Center. But, this makes little sense to me, since DTRC had little or no experience in aircraft design. It really does look like the Superfly (SF-121) and DTRC may well have used that as a placeholder for their VATOL carrier design.

File:428-GX-KN-31380 (24463970746).jpg - Wikimedia Commons

commons.wikimedia.org

428-GX-KN-31380: Artist Conception of the Short Takeoff and Vertical Landing (STOVL) fighter concept, developed by the David W. Taylor Naval Ship and Research and Development Center, in various stages of flight and recovery positions near the 325 foot small water plane area twin hull ship (SWATH), received February 1981. Artist is unknown. U.S. Navy Photograph now in the collections of the National Archives. Photographed from reference card only.

Awesome, thank you very much.

 

[TomS]

To add, we have a thread about the Superfly concepts, including a different view of the plane around a similar carrier concept.

https://www.secretprojects.co.uk/threads/vought-ltv-sf-106-and-sf-121-superfly-vatol-fighters.15491/post-583284

 

[Scott Kenny]

Can someone explain having both SH-2 Seasprites and SH-3 or even SH-53 helicopters on the baby carriers?

 

[that_person]

If I had to guess? SH-3s are huge. They have a lot of lift capability and a lot or range, thus making them good for utility and reduce duties, but they have to the space of 2(?) Seasprites. You’d have a SH-3 or two for utility, and the SH-2s to boost airwing numbers.

 

[Scott Kenny]

If I had to guess? SH-3s are huge. They have a lot of lift capability and a lot or range, thus making them good for utility and reduce duties, but they have to the space of 2(?) Seasprites. You’d have a SH-3 or two for utility, and the SH-2s to boost airwing numbers.

I like your reasoning, but the published proposed air wings had 2-6 Seasprites and 6-14 H-3/H-53s, depending on proposal size.

Maybe using the Seasprites as close in ASW and the bigger helos for long range ASW and whatever heavy lifting needed to happen?

 

[aim9xray]

Sea Sprite as plane guard?

 

[Hood]

The LAMPS Seasprite was limited to MAD and sonobuoys, whereas the SH-3 had dipping sonar so could perform screening operations. I guess they would have formed two rings, Sea Kings on the outer rim and Seasprite closer in and linked to the sonar contacts from the ships themselves. Plus the Seasprite had an anti-ship role too with Mavericks which would have been handy.
I guess had these been built they would have ended up with a uniform group of Seahawks anyway.

 

[TomS]

Plus the Seasprite had an anti-ship role too with Mavericks which would have been handy.

I don't think Maverick was ever part of the SH-2 LAMPS armament before the SH-2G, and even then only on the export examples. I only found one older image of an SH-2 with a possible Maverick and I'm pretty sure it's just a trials bird for the G. (I'm not even completely convinced it's a Maverick outboard in this photo -- I can't see the fins very well)



In VSS/SCS airwings with only 2 SH-2, I agree that plane guard was the intended role. In the larger air wings with as many as 6 SH-2, I'd guess some were expected to be doing ASMD roles, something they were experimenting with for LAMPS at the time.



Also, they may have intended the VSS to provide maintenance to SH-2s embarked on the accompanying escorts. So some of those LAMPS aircraft might have essentially been spares to loan out to accompanying frigates while their own aircraft were being worked on.

 

[Scott Kenny]

Okay, that makes a little more sense.

And using the VSS as basically an ASW carrier for convoy escorts definitely makes the "spare LAMPS" a possibility.

 

[Kat Tsun]

Can someone explain having both SH-2 Seasprites and SH-3 or even SH-53 helicopters on the baby carriers?

The H-2/H-3 is already covered and the H-53's would be for minesweeping.

 

[Scott Kenny]

The H-2/H-3 is already covered and the H-53's would be for minesweeping.

Except that the Minesweepers get MH-53 designations while these are SH-53, as in sub-hunting.

Posted by Triton:



Sea Control Ship (SCS)

Specifications of preliminary design January 1972 from U.S. Aircraft Carriers: an Illustrated Design History by Norman Friedman.

Light displacement (tons): 9,773
Full load (tons): 13,736
LOA (ft-in): 610
LWL (ft-in): 585
Beam (WL/EXT): 80
Draft (full load) (ft-in): 21.62-0
Depth (ft-in): 67.5-0
SHP: 45,000
Speed (kts): 26 (24.5 sustained)
CIWS: 2

Aircraft (typical embarked):
3 AV-8A (Hawker Siddeley Harrier)
2 LAMPS (Kaman SH-2 Seasprite)
14 SH-3 (Sikorsky Sea King)

VSTOL Support Ship (VSS) I

Specifications from U.S. Aircraft Carriers: an Illustrated Design History by Norman Friedman.

Light displacement (tons): 15,210
Full load (tons): 22,940
LOA (ft-in): ?
LWL (ft-in): 690-0
Beam (WL/EXT): 98.45/133.5
Draft (full load) (ft-in): 23.23-0
Depth (ft-in): 73.50-0
SHP: 90,000
Speed (kts): 28 sustained
CIWS: 2
Harpoon canisters: 2
Aircraft (typical embarked):
4 AV-8A (Hawker Siddeley Harrier)
6 LAMPS (Kaman SH-2 Seasprite)
16 SH-53 (Sikorsky Sea Stallion)



VSTOL Support Ship (VSS) II

Specifications from U.S. Aircraft Carriers: an Illustrated Design History by Norman Friedman.

Light displacement (tons): 17,380
Full load (tons): 26,334
LOA (ft-in):717-0
LWL (ft-in): 690-0
Beam (WL/EXT): 105.7/166.5
Draft (full load) (ft-in): 24-5
Depth (ft-in): 77-1
SHP: 90,000
Speed (kts): ?
CIWS: 2
Harpoon canisters: 2
Aircraft (typical embarked):
4 AV-8A (Hawker Siddeley Harrier)
6 LAMPS III
16 SH-53 (Sikorsky Sea Stallion)



From Jane's Fighting Ships from the late 1970s


Sea Control Ship (SCS) Design
-----------------------------
Displacement, tons: 14,300 full load
Length, feet (meters): 640 oa (195-1)
Beam, feet (meters): 80 (24-4)
Draught, feet (meters): 30 (9-1)

Aircraft:
3 VSTOL strike aircraft
14 large A/S helicopters
2 LAMPS helicopters

Also, notice the number differences. Only a couple of the small helicopters, and 14-16 of the large helicopters.

 

[A Tentative Fleet Plan]

Using CH-53s for ASW has shades of UK plans for using Chinooks to meet NASR.358.

 

[Scott Kenny]

Using CH-53s for ASW has shades of UK plans for using Chinooks to meet NASR.358.

Which is why I was so confused.

 

[Hood]

The CH-53 is probably a stand-in/interim long-range ASW helicopter.
These VSS designs are a 3-4 years before the Type A V/STOL requirement was launched in 1976, so it would seem that long-range VTOL ASW was always considered for these ships, in effect a VTOL-capable S-3 analogue.

 

[TomS]

Except that the Minesweepers get MH-53 designations while these are SH-53, as in sub-hunting.

The minesweeping helo of this era was the RH-53 not the MH-53, but yes, these were definitely not minesweepers.

It's worth noting that the H-53 isn't that much bigger than the SH-3. It's actually a foot narrower when folded up and just 9 feet longer, so the stowed area is only about 13% greater. The cabin was substantially larger, of course, with about 40% more floor area and volume.

At the time, helicopter ASW gear was in a state of flux. The SH-3D had only dipping sonar. The SH-3H was just coming in from 1971, with radar, ESM, dipping sonar, and hand-launched sonobouys. Incorporating a proper sonobouy launcher and advanced acoustic processors to fully exploit the sonobouys could well have pushed for an even larger aircraft. And as @Hood says, this was probably a placeholder for that larger, more capable VSTOL Type A.

Interestingly, the Navy was planning to initiate an SH-3 successor aircraft, called HSX, in FY1975, with the goal of using it to also replace the CH-46. Shades of JVX (later V-22). HSX was cancelled somewhere around 1977.

https://history.defense.gov/Portals/70/Documents/annual_reports/1975_DoD_AR.pdf?ver=2014-06-24-150705-323

The SCS with the SH-3H and the AV-8A would provide a useful capability at a relatively low cost, thus facilitating its acquisition in quantity. Moreover, like all air-capable ships, the SCS would be equipped, over its lifetime, with several generations of aircraft. Development of a new, more capable ASW aircraft, the HSX, is now under consideration, and eventually a new, improved V/STOL fighter will become available. These new aircraft would further improve the combat capabilities of the SCS.

HSX As noted earlier, the HSX is being developed as an eventual replacement for the SH-3H, as well as the Marine Corps' CH-46 medium assault helicopter, sometime in the 1980s. The HSX would have better ASW sensors and avionics than the SH-3, and greater endurance and payload. Thus ,it would provide an improved ASW capability against the quieter and more capable Soviet submarines expected in the 1980s. Some $2 million is included in the FY197 5Budget to initiate development of the HSX.

 

[TomS]

There's a brief history of the Marine HXM, which was briefly lashed up with the Navy HSX, here:

https://www.secretprojects.co.uk/th...lopment-and-proposed-variants.1309/post-29679

 

[Scott Kenny]

Okay, now I think I get it.

Thanks, all!

 

[Archibald]

Meanwhile, the SCS operational concept was
being tested at sea. Alternative platforms were evalu-
ated during 1971, the best being a Commencement
Bay-class escort carrier—which it would cost $73
million merely to make seaworthy. The next best
choice was a helicopter /carrier, the (LPH) Guam being
selected and modified from October 1971 through
January 1972.

U.S. Aircraft Carriers An Illustrated Design History (Norman Friedman) p.354

Commencement Bay-class escort carrier - Wikipedia

en.wikipedia.org

By 1969 a large fraction of the 19 Commencement Bay carriers commissioned (11 of them) hasn't been scrapped yet. So plenty of choice for candidate SCS.

 

[orlovsky]

I would tend to agree. The similarly sized Clemenceau had a max spotting of approx 54 A-7s (my rough estimate below), so 72 A-7s sounds very implausible.

Interesting question. That would translate into 60 A-4 spots vs 106 on an Essex, I've been trying the A-4/Clem, and came up with maybe 67. A 60-75% advantage for the essex looks a bit much though, with displacement after several refits (and probably weight gain) what, 1/3 larger?

I guess the reason is that the spotting exercises here are still closer to operational spotting than the one used for the theoretical maximum. For example in this blog entry by Thomason, the white on black is operational, while the outline drawings below are "theoretical" for spotting factors: https://thanlont.blogspot.com/2010/07/fitting-in-ii.html . Another comparison "The example above* is an operational spot of the Hancock, as opposed to a spotting factor exercise." ( https://thanlont.blogspot.com/2009/07/fitting-in.html )

So for the pure spotting factor exercise, 72 A-7 might be just squeezed into the design.

 

[H_K]

That would translate into 60 A-4 spots vs 106 on an Essex, I've been trying the A-4/Clem, and came up with maybe 67. A 60-75% advantage for the essex looks a bit much though, with displacement after several refits (and probably weight gain) what, 1/3 larger?

Essex is better compared to PA-58. See 2 drawings below...

They are very similar in size. The main difference is Essex's short and very angled deck leaves the bow clear for a larger deck park. Also Essex's aviation workshops and munitions handling spaces on the hangar level were tiny (probably a legacy of WW2 design), leaving more space for aircraft in the hangar.. in theory at least. I don't have the latest Vietnam-era plans to know how much of that hangar space had to be repurposed for workshops and munitions prep.

For PA-58 I get about 75 F-8 Crusaders (36 in hangar and 38 on deck). That translates to ~95 A-7 or ~101 A-4 equivalents... close enough to Essex considering the differences above. I haven't done an A-7 or A-4 spotting exercise to confirm though.

 

[Archibald]

Interesting good job as usual, @H_K
There were also those studies, well worth a comparison.

https://www.secretprojects.co.uk/threads/scb-100-class-cvs.42298/

 

[that_person]

I know this is a bit offtopic, but in the context of a modern CVE, wouldn’t a tiltrotor of sufficient size give you similar capabilities to an S-3?

Something like the V-280 has similar range, sufficient speed, plus the ability to use a dipping sonar. The payload would be a bit lighter, but the smaller size means you can make up for that in numbers. Other benefit is you don’t need to pay for a catapult.

 

[TomS]

I know this is a bit offtopic, but in the context of a modern CVE, wouldn’t a tiltrotor of sufficient size give you similar capabilities to an S-3?

Something like the V-280 has similar range, sufficient speed, plus the ability to use a dipping sonar. The payload would be a bit lighter, but the smaller size means you can make up for that in numbers. Other benefit is you don’t need to pay for a catapult.

An SV-22 was several times proposed as an ASW platform either to replace or supplement the S-3. It could even dip sonar, in theory (but we know the V-22 is not efficient in the hover, so it's far from ideal for dipping).

 

[orlovsky]

They are very similar in size. The main difference is Essex's short and very angled deck leaves the bow clear for a larger deck park. Also Essex's aviation workshops and munitions handling spaces on the hangar level were tiny (probably a legacy of WW2 design), leaving more space for aircraft in the hangar.. in theory at least. I don't have the latest Vietnam-era plans to know how much of that hangar space had to be repurposed for workshops and munitions prep.

For PA-58 I get about 75 F-8 Crusaders (36 in hangar and 38 on deck). That translates to ~95 A-7 or ~101 A-4 equivalents... close enough to Essex considering the differences above. I haven't done an A-7 or A-4 spotting exercise to confirm though.

That exercise would be interesting.
The forward deck park and the hangar explain the advantage of the essex class over Clemenceau, but PA58 is ~20m longer and looks like it has a similar flight deck width.
The F-8A SAC says 81 on an essex. How many would you get with similar spotting as on PA58?

 

[H_K]

The F-8A SAC says 81 on an essex. How many would you get with similar spotting as on PA58?

Haven't tried spotting F-8s yet but I got 103 A-4s on an Essex (56 on flight deck and 47 in the hangar)... so very close to the 106 maximum mentioned in the A-4 SAC.

I could try the same on PA-58 so we could have an apples-to-apples comparison... though obviously still a rather theoretical exercise as real world air wing capacity depends on lots of other factors too.

 

[Scott Kenny]

I know this is a bit offtopic, but in the context of a modern CVE, wouldn’t a tiltrotor of sufficient size give you similar capabilities to an S-3?

Something like the V-280 has similar range, sufficient speed, plus the ability to use a dipping sonar. The payload would be a bit lighter, but the smaller size means you can make up for that in numbers. Other benefit is you don’t need to pay for a catapult.

In theory, yes. Depends on just how much the ASW gear weighs, and whether you're dropping little torpedoes or if Big Navy decides to start airdropping 21" torpedoes again.

 

[orlovsky]

Haven't tried spotting F-8s yet but I got 103 A-4s on an Essex (56 on flight deck and 47 in the hangar)... so very close to the 106 maximum mentioned in the A-4 SAC.

I could try the same on PA-58 so we could have an apples-to-apples comparison... though obviously still a rather theoretical exercise as real world air wing capacity depends on lots of other factors too.

Impressive, I would have expected something more like ~90.

 

[Nico]

Hello friends, about the Sea Control Ship program of US Navy, in the posts on the American V/STOL projects we have a good amount of information, data and illustrations. However, I was unable to find a date (month and year) in which the Requests For Information relating to Type A and Type B were published. Can you illuminate?Thank you
Nico

 

[orlovsky]

I've tried the A-4s on Foch again, and if I haven't screwed up the scaling, I get 70 (theoretical) A-4 spots.

As airplanes are not liquids the A-4/A-7 ratio of 0.9 can vary, but this is quite a difference to 54 A-7s. Puts us closer to the Essex, though (470 tons per spot on Foch vs 420 tons on Essex).

As for the 72 A-7 spots ship, could it be that it was actually 72 A-4 spots?