*Possibly* New GC ship for 1919

[The Rock Doctor]

So this is the "horrific" thing I alluded to in the 1/19 thread.  Private consultations have yielded very divergent opinions so far.

Here's the background.  The Colombians have been tinkering with ship/blimp combinations for a few years now.  In 1917, they started building a dedicated blimp carrier, but as construction progressed in 1918, a problem became evident:  the short, low-draught/high freeboard hull weathervanes (exactly as some players said it would).  

A follow-up unit is now proposed, for supporting battleline operations.  Studies suggest that a longer, deeper hull - with a long rectangular blimp shed rather than a short, squarish one - would have much reduced trouble with weathervaning.  However, the hull needs to remain reasonably wide, otherwise the high freeboard will cause it to have low stability.  

So the hull is really big, with lots of unused space above and below deck.  Below, the Colombians opt to give her machinery to develop 27 knots - this gives her a margin to manuever away from and back to the battleline when it's at flank speed.  Since the shed sits on the centreline, the exhaust gets trunk to one side.

Above deck, above the main/gun deck, two lightweight, narrow hangers are stack on either side of the shed.  Each of the four narrow hangers can hold, in theory, eight observation seaplanes and a single wheeled fighter, all with wings folded.  One hydraulic lift serves each hanger stack.  Three cranes are installed on sponsons to lift the seaplanes back aboard, while the fighters will have to ditch alongside a rescue ship.

Two flying-off decks are installed; both slant downward to aid in the take-off run.  The upper deck would be equipped for launching seaplanes with trolleys.  The bridge is installed under the upper flying-off deck, though a small pole mast is sited to starboard on the top-most deck.

Armament is cruiser-ish.  Four pairs of single 5.5" guns, plus a ninth, single gun opposite the funnels.  Four AA guns sit up on the upper flight deck.  Armor is cruiser-ish as well.  

The airgroup is - initially - four wheeled fighters, and around twenty scouting/observation floatplanes, plus two Type-0 blimps.  The airgroup allows for several aircraft to operate in recce roles, holding six on standby to spot for the half-dozen battleships of the battleline, plus a few spares to cover for losses or maintenance.  Obviously, additional space is available for an expanded airgroup later, but I figure initially the space will be used to shuffle aircraft around the somewhat inefficient hanger layout without resorting to deck-parking.

Were the ship to be built, she'd probably face a mid-life reconstruction into a proper full-deck carrier, with two full-length hanger decks.  However, that's years away.

So...

1)  Is 1919 too soon for such a ship for the Colombians?

2)  Bearing in mind the lack of historical precedent for the airgroup, and the ship's quasi-prototype status - does the concept seem reasonably technically sound?  

Specs will follow in the next post - the drawing is here:

[The Rock Doctor]

...and the specs.

Enter ship name, Enter country Enter ship type laid down 1912 (Engine 1916)

Displacement:
   16,432 t light; 16,902 t standard; 19,014 t normal; 20,703 t full load

Dimensions: Length overall / water x beam x draught
   722.11 ft / 710.63 ft x 95.14 ft x 19.69 ft (normal load)
   220.10 m / 216.60 m x 29.00 m  x 6.00 m

Armament:
      9 - 5.51" / 140 mm guns in single mounts, 83.72lbs / 37.97kg shells, 1912 Model
     Breech loading guns in deck mounts with hoists
     on side, evenly spread
      4 - 2.56" / 65.0 mm guns in single mounts, 8.38lbs / 3.80kg shells, 1912 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
      6 - 0.31" / 8.0 mm guns in single mounts, 0.02lbs / 0.01kg shells, 1912 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 787 lbs / 357 kg
   Shells per gun, main battery: 200

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   2.95" / 75 mm   462.60 ft / 141.00 m   16.01 ft / 4.88 m
   Ends:   0.98" / 25 mm   248.03 ft / 75.60 m   12.14 ft / 3.70 m
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead:
      1.57" / 40 mm   462.60 ft / 141.00 m   17.32 ft / 5.28 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.97" / 50 mm   0.98" / 25 mm      2.95" / 75 mm
   3rd:   0.98" / 25 mm         -               -
   4th:   0.39" / 10 mm         -               -

   - Armour deck: 1.57" / 40 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 4 shafts, 64,000 shp / 47,744 Kw = 27.04 kts
   Range 20,000nm at 10.00 kts (Bunkerage = 3,801 tons)

Complement:
   809 - 1,052

Cost:
   £0.992 million / $3.966 million

Distribution of weights at normal displacement:
   Armament: 98 tons, 0.5 %
   Armour: 2,891 tons, 15.2 %
      - Belts: 1,044 tons, 5.5 %
      - Torpedo bulkhead: 467 tons, 2.5 %
      - Armament: 67 tons, 0.4 %
      - Armour Deck: 1,312 tons, 6.9 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 2,385 tons, 12.5 %
   Hull, fittings & equipment: 8,570 tons, 45.1 %
   Fuel, ammunition & stores: 2,581 tons, 13.6 %
   Miscellaneous weights: 2,489 tons, 13.1 %
-1,296 t:  Facilities for 36 aircraft
-500 t:  Facilities for two Type-0 blimps
-100 t:  Fire control
-100 t:  Operations facilities
-493 t:  Weight reserve / "the blimps require a lot of volume but not a lot of weight so there's extra hull strength")

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     54,857 lbs / 24,883 Kg = 655.2 x 5.5 " / 140 mm shells or 7.1 torpedoes
   Stability (Unstable if below 1.00): 1.27
   Metacentric height 7.2 ft / 2.2 m
   Roll period: 14.9 seconds
   Steadiness   - As gun platform (Average = 50 %): 80 %
         - Recoil effect (Restricted arc if above 1.00): 0.09
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has low forecastle, rise forward of midbreak, low quarterdeck
   Block coefficient: 0.500
   Length to Beam Ratio: 7.47 : 1
   'Natural speed' for length: 26.66 kts
   Power going to wave formation at top speed: 45 %
   Trim (Max stability = 0, Max steadiness = 100): 40
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 6.56 ft / 2.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      27.89 ft / 8.50 m
      - Forecastle (27 %):   21.98 ft / 6.70 m (45.93 ft / 14.00 m aft of break)
      - Mid (77 %):      45.93 ft / 14.00 m (21.98 ft / 6.70 m aft of break)
      - Quarterdeck (16 %):   14.11 ft / 4.30 m (21.98 ft / 6.70 m before break)
      - Stern:      14.11 ft / 4.30 m
      - Average freeboard:   33.33 ft / 10.16 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 76.1 %
      - Above water (accommodation/working, high = better): 456.0 %
   Waterplane Area: 45,049 Square feet or 4,185 Square metres
   Displacement factor (Displacement / loading): 174 %
   Structure weight / hull surface area: 126 lbs/sq ft or 615 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.91
      - Longitudinal: 2.21
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

[TexanCowboy]

IDK...for that to be effective, I think you need 1918 carrier, which you can't have till 1920. I would wait for operational expieriance from the new floatplane cruisers before you do this...

[maddox]

The flying off deck is very advanced, I would delete that and rely on crane placed float planes, or, the strange, but useable Blimp lift  approach.

That last technique is a rarely used setup were a large balloon took up a glider to a certain hight and dropped the glider. The same could be done with an aircraft, if the engine was idling before  lifting it off the deck.

[P3D]

Depends on how conservative your admiral are, but the top flight deck might be way too high for them. But feasible.

My main concern is whether the 70m take-off distance from the lower flight deck is long enough.

Hangars are too crowded (only a 4 plane being accessible at any given time unless parked on the deck), after a few months of trial I'd guess the airgroup would be decreased by 1/4th, dedicating one of the lower hangars for maintenance.

And yes, 1918 Carrier tech (Furious).

[Carthaginian]

I like the concept- it is unique and still plausible.

I see it as PERFECTLY in keeping with Colombian doctrine.

I also, like TC, see it as being on the next level of carrier tech.
That being said, I look forward to seeing her built.

[The Rock Doctor]

Why the 1918 tech, guys?

[TexanCowboy]

Well, unless you want to be able to land the planes...

Honestly, doing the review, I think you would be better off building some modified Matadi's with capacity for a floatplane.

[The Rock Doctor]

There's a mooring mast obstructing the aft of the flight deck.  I don't think landing is a practical consideration.

I'm giving thought to a modified Cesar class cruiser with one or two floatplanes, but that's a differrent kettle of fish.

[TexanCowboy]

Matadi! Matadi! Who doesn't want a flagship that's 1,000 tons with floatplanes!

[The Rock Doctor]

Yes, I did that in Wesworld.  Could do it again here, I suppose.

I have tinkered with another idea - a destroyer with a small ramp and single fighter forward, and several AA guns aft,  An interceptor of airships, as it were.

[P3D]

Why the 1918 tech, guys?

Pretty similar to the first full carrier conversions, the Furious (the conversion starting in 1921) and Langley (1920). It's not only a single deck plated over the gun mounts as the experimental Vindictive/first Furious ones.

Furious at first had a 160' fly-off deck so that's apparently enough.
On the funnels: having them off to the side of the superstructure seems odd, and ugly.
Granted, taking the funnels within the superstructure would limit hangar space, but 64000SHP could be trunked into one single (at most two) funnel easily below the first hangar deck, you don't need three.

[ctwaterman]

Im broken about the is this a 1918 Tech Carrier built earlier simply waiting for transformation to a full carrier after 1920 or just a really really good design for a combination float plane/blimp carrier.

Honestly its a brillaint adaption and if I had the BP the Italians would steal the design.   It in effect creates a reason for the fly on fly off carriers in the Future.
Its a novel approach to the problem of the Blimb Carrier and so what if some time in the Mid 1920 someone realizes that a few simple reinforcements to the top of the Blimp Hanger means you can land planes on it while its running into the wind.  ;)

[Nobody]

I like mostly because it looks exactly like I envisioned my own airship carrier designs.

However, how big is a "Type 0 Blimp"? The first OTL Zeppelin with 11300 m³ just 13% larger than our type 0 tech was already 128 m long and 11.7 m in diameter.
You avoided stability problem by rising the hull some 7 m - in contrast to my 30 - both approaches seem unrealistic to me. Maybe we need a rule of thumb to specify how much is necessary (something between 1/2 and 2/3 of the desired hanger hight seems adequate to me)

btw isn't the ship just a tad too long? (10 cm to be precise)

[maddox]

http://en.wikipedia.org/wiki/SS_class_blimp


The largest WW I blimps have better endurance, speed and cargo capacity than our type 0 Blimps, but the rules are the rules.