Verdun French Aircraft Carrier (images)

orlovsky said:
The issue of the catapults is closely related to Verdun and other projects like Hermes refits or CVA-01. Don't know whether it merits a thread of its own, I'll just add this:

Returning to the table above and comparing with the bs5 from the McD F-4K report, the catapults have similar performance even though the british boilers provided much lower pressure:

Clem Ark
33k lbs 110 ~110
40k lbs 100 ~100

Some snippets on google books suggest that the Clems had (initially?) bs4 catapults. A later improvement is likely, otherwise the F-8 would have been extremely marginal.

According to Friedman, Postwar Naval Revolution: "The first British steam catapult , BS4 , could launch 30,000 pounds at 105 knots in its least powerful version". Length not mentionned.
Hobbs has for
Centaur: bs4 139 ft 40k lbs @ 94 kts
Victorious: bs4 145ft 50k lbs @97 kts (better than the slightly longer bs5)
Hermes: bs4 175 ft and 151 ft, both 50k lbs @ 94 kts (odd and from other sources, these lengths were only planned for the F-4)
Eagle and Ark: bs5 151 ft 50k lbs @ 91 kts, abs5 199 ft 50k lbs @105 kts (as in the F-4K charts)

And on some forums, there is the BS4 103ft with 40,000lb@78kt (which fits the Centaur data)

As the numbers are all over the place, I suggest the hypothesis that
- the change of bs mk4 to mk5 included an improvement, somewhere in the 10-15 kts region
- that change was probably retrofitted to the carriers still in service

Unfortunately, from the sources available, it is unclear what that change was.
Click to expand...

Amazon now has the softcover version of Moulin's book on Clemenceau and Foch for Kindle. From this, a part of the puzzle can be solved.

He states a more powerful 51,5m (169 ft) bs5 with 110 kts @ 20 metric t replacing a bs4 with 95 kts @ 20t, 110 kts @ 15t and 130 kts @11t.
Together with the table from old training material I linked above, this means the catapult was improved, but also extended from 157 to 169 ft (fitting the 12 ft increments). He does not say when this happened, but it's probably related to the crusader buy.

For comparison, this improved bs5 is about 15 kts better than the 151ft bs5 Ark Royal bow cat, about equal to the 199ft bs5a Ark waist cat, and maybe 10-12 kts short of the C-11.

It would require about 20 kts wod for the F-8J, 20-25 kts for the F-4B (internal fuel/missiles only) and something in that ballpark for the F-18 in fighter trim (1 droptank, missiles). Fits nicely with the F-8 operating smoothly and no big problems seen for the F-18.

This should also explain the various claims that the Clems were limited to 15 or 18 ton jets: The initial bs4 or the short bs5 on RN carriers would be marginal for say the F-8 (30-32k lbs, 30-35 kts wod).

Extending the improved bs5 to 75m as in the PA-58 projects should result in something like the USN's C-7 catapult.

Some other interesting stuff in that book...
 
The above post is BRILLIANT. Lots of things immediately came to my mind reading it

1- This explains why a Clemenceau could not handle a Phantom (or a Hornet, or a Rafale !) or marginally at best, closer from 1959 Hermes... or a SBC-125 Essex, in that regard.

2- (in 1963 France considered both - Phantom AND Crusader. Wanted the former, like the British; went for the later)

3- But an Audacious, or... the CdG can handle all three of them: Phantom, Hornet or Rafale. All of them 18 - 25 tons in weight.
a) Because the Ark Royal had the 199 ft BS-5A, rather than a truncated-to-171-feet BS-5 as the Clems - or Hermes BS-4
b) because the CdG actually has a truncated C-13 : 75 m long (rather than a Nimitz' 95 m - but otherwise, the very same).

4- (yes, France put a catapult from a 90 000 tons carrier on a 45 000 tons one - but sacrifices had to be made... !)

5- Bottom line: 1959-Hermes-Centaur, SBC-125-Essex, and Clemenceaus all had the same issue: they were just a touch too small for a Phantom.
a) USN validated Phantoms on SBC-125 Essex carriers, but it remained marginal: Crusaders clearly were the prefered option
b) RN FAA bought more powerful Phantoms with Speys, but they were marginal on Hermes, not much better on Victorious, and took heavy rebuild of Audaciouses to get the full potential
c) MN considered Phantoms before Crusaders for the Clemenceaus, but went for Crusaders in the end.

6- so what was the right size to operate Phantoms properly ? (and Hornets later, and Rafales even later: 1960, 1980, 2000 !)
a) Midway rather than Essex
b) Audacious rather than Hermes
c) Verdun or CdG rather than Clemenceau

7- There is clearly a heavy trend there, converging to 42 000 - 55 000 tons, rather than 25 000 - 35 000 tons.

8- The tipping point seems to be 40 000 tons. Clemenceaus were below that treshold, PA58 & CdG were / are above it.
 
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Archibald said:
3- But an Audacious, or... the CdG can handle all three of them: Phantom, Hornet or Rafale. All of them 18 - 25 tons in weight.
a) Because the Ark Royal had the 199 ft BS-5A, rather than a truncated-to-171-feet BS-5 as the Clems - or Hermes BS-4
b) because the CdG actually has a truncated C-13 : 75 m long (rather than a Nimitz' 95 m - but otherwise, the very same).
Click to expand...

Well, you can launch them like the Ark - even better, you have two cats strong enough. But it's still light weights only.

And then, landing seems to have been the bigger problem.... :eek:
 
Another aspect: Crusaders for Hermes are not an easy option; more likely, no option: catapults -15 kts, speed -5 kts, so a 20 kts gap compared to the Clems.
 
Julio Garay Terrazas said:
I don't remember where i get this image, but in the file data said year 2005.
Click to expand...
Verdun_class_CV.jpg
The dimensions of PA58 in the image are somewhat peculiar.
Length​
860ft 0in (262.0m) waterline.​
880ft 4in (268.3m) overall.​
940ft 5in (287.0m) flight deck.​
Beam​
104ft 1in (31.7m) waterline​
192ft 0in (58.5m) flight deck. It actually says 1192ft but I think that's a typo for 192ft because 58.5m =191ft 11in and a bit.​

The flight deck length is longer than the overall length, which can't be correct. The waterline beam is the same as the waterline beam for Clemenceau & Foch in Conway's 1947-1995.

The dimensions for PA58 in Conway's 1947-1995 have been quoted in this thread (e.g. by @alejandrogrossi in Post 78) and they are:
Length​
860ft pp​
939ft overall​
Beam​
112ft waterline​
190ft flight deck​

@alejandrogrossi in Post 78 had also has a line drawing from another source whose dimensions match those in Conway's i.e.:
Length​
939ft overall length​
939ft flight deck length​
Beam​
112ft waterline​
190ft flight deck​

Therefore, is:
860ft 0in (262.0m) the pp length? Because 860ft is the pp length in the other sources.​
880ft 4in (268.3m) the waterline length?​
940ft 5in (287.0m) the overall length? Because it's close to the overall length of 939ft in the other sources.​
104ft 1in (31.7m) for the waterline beam wrong? Because, the other sources say 112ft.​
 
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I found this thread because I'm doing a comparison of the Clemenceau class, PA58 & Charles de Gaulle and am looking for the waterline lengths of Clemenceau & PA 58 and the pp length of Charles de Gaulle. This is because my reference books have the pp lengths for Clemenceau & PA 58 but not their waterline lengths and the waterline length for CdG but not her pp length.

The information that I have from Conway's 1947-1995 is.
781ft (238.0m) pp length of Clemenceau​
860ft (262.0m) pp length of PA58​
781ft (238.0m) wl length of Charles de Gaulle​

Does anyone have the missing information?

Edit 12.27 PM GMT Thursday 09.11.23.
To be absolutely clear, the questions that I am asking, are:
  • What was the waterline length of Clemenceau?
  • What was the waterline length of PA58.
  • What was the between perpendiculars (pp) length of Charles de Gaulle?
 
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A Tentative Fleet Plan said:
John Jordan's article on the Clemenceau and Foch in Warship 2023 puts Clemenceau's length as 238 metres between perpendiculars, and 257.5 metres overall.
Click to expand...
Thank you for the information.

However, that doesn't help, because I want to know her waterline length, not her between perpendiculars length.

I knew that Clemenceau's between perpendiculars length was 238.0 meters (781ft) because my copies of Conway's 1947-1995 & Roger Chesneau's aircraft carriers book say so. That's why I was able to write "781ft (238.0m) pp length of Clemenceau" in Post 88.

Incidentally both books say that the overall length of Clemenceau was 265.0m (870ft) not 257.5m (845ft).
 
NOMISYRRUC said:
Thank you for the information.

However, that doesn't help, because I want to know her waterline length, not her between perpendiculars length.

I knew that Clemenceau's between perpendiculars length was 238.0 meters (781ft) because my copies of Conway's 1947-1995 & Roger Chesneau's aircraft carriers book say so. That's why I was able to write "781ft (238.0m) pp length of Clemenceau" in Post 88.

Incidentally both books say that the overall length of Clemenceau was 265.0m (870ft) not 257.5m (845ft).
Click to expand...
The extra length is the bow mounted catapult bridle catcher.
 
@NOMISYRRUC I’m attaching some info from the Foch ship plans available here… you can download to view them in high definition.

French Aircraft Carrier FOCH as Build 1960 | 3DHISTORY.DE

French Aircraft Carrier FOCH as Build 1960 – 39 Sheets Scale 1/200, Scale 1/100 and Scale 1/20 (This sets of drawings were released into the public...
3dhistory.de

Length PP and WL were both 238m.
Length OA was 258.727m
(Not counting removable nets and the bridle catcher added later)
Displacement at the design draft of 7.5m was 28,300 mt.
The plans also show clearly the bulges that were added.l during construction.
 

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PP should never equal to waterline length because of the definition of the PP being calculated from the centre pivot of the rudder to the waterline on the nose, while pure waterline is between the tow end points of the hull on waterline level.
Of course myself too seen such values on official US documents though the waterline length omitted but the value stated for PP corresponded to numerous sources of said ship's waterline length. (Essex class carrier for example)
 
@Tzoli Well apparently different countries have different practices. On the official Foch plans the mark for “PP AR” (aft perpendicular) is set at the stern waterline and the “length between perpendiculars” is drawn as an arrow all the way from bow to stern, and clearly marked as 238m.

The rudder post is 6m in front of the stern PP mark, so yes “real” LPP to the rudder post would be 232m.

@NOMISYRRUC to answer your question about CdG’s waterline length it appears to be roughly 247m, based on scaling the 138m long hangar below. I’ve marked the waterline in red and the rudder post in blue which gives you an LPP of 238m.
 

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H_K said:
@NOMISYRRUC I’m attaching some info from the Foch ship plans available here… you can download to view them in high definition.

French Aircraft Carrier FOCH as Build 1960 | 3DHISTORY.DE

French Aircraft Carrier FOCH as Build 1960 – 39 Sheets Scale 1/200, Scale 1/100 and Scale 1/20 (This sets of drawings were released into the public...
3dhistory.de

Length PP and WL were both 238m.
Length OA was 258.727m
(Not counting removable nets and the bridle catcher added later)
Displacement at the design draft of 7.5m was 28,300 mt.
The plans also show clearly the bulges that were added.l during construction.
Click to expand...
The plans for the Clemenceau don’t show the bulges, as they weren’t retrofitted until 1966! Foch was built with them. Personally, I think the stability issues
corrected by the bulges weren’t severe. As to the source of the stability issue, I have my suspicions.
 

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