WesWorld

The RN has long seen the need for a support ship for carrier operations far away from home bases. This ship has the spare aircraft, workshops, stores and armament to support two fleet carriers. One ship will be built, possibly two if the carrier fleet extends further. Unicorn will carry two small self-propelled lighters which will be carried in a aft bay hoisted by moving gantry.



HMS Unicorn, Great Britain Aircraft Carrier Tender laid down 1938

Displacement:
17,028 t light; 17,487 t standard; 18,570 t normal; 19,437 t full load

Dimensions: Length overall / water x beam x draught
620.01 ft / 575.00 ft x 96.00 ft x 18.90 ft (normal load)
188.98 m / 175.26 m x 29.26 m x 5.76 m

Armament:
8 - 4.50" / 114 mm guns (4x2 guns), 45.00lbs / 20.41kg shells, 1936 Model
Dual purpose guns in deck mounts with hoists
on side ends, evenly spread
8 - 1.57" / 40.0 mm guns (2x4 guns), 2.00lbs / 0.91kg shells, 1922 Model
Anti-aircraft guns in deck mounts
on side, all amidships
24 - 0.66" / 16.8 mm guns (4x6 guns), 0.14lbs / 0.06kg shells, 1936 Model
Machine guns in deck mounts
on side ends, evenly spread, all raised mounts - superfiring
Weight of broadside 379 lbs / 172 kg
Shells per gun, main battery: 400

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 4.00" / 102 mm 140.00 ft / 42.67 m 10.00 ft / 3.05 m
Ends: Unarmoured
Main Belt covers 37 % of normal length
Main belt does not fully cover magazines and engineering spaces

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.50" / 38 mm 1.00" / 25 mm 1.00" / 25 mm
2nd: 0.50" / 13 mm - -
3rd: 0.50" / 13 mm - -

- Armour deck: 2.00" / 51 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 40,000 shp / 29,840 Kw = 24.03 kts
Range 10,000nm at 12.00 kts
Bunker at max displacement = 1,950 tons

Complement:
795 - 1,034

Cost:
£4.450 million / $17.802 million

Distribution of weights at normal displacement:
Armament: 48 tons, 0.3 %
Armour: 1,963 tons, 10.6 %
- Belts: 339 tons, 1.8 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 33 tons, 0.2 %
- Armour Deck: 1,591 tons, 8.6 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 1,095 tons, 5.9 %
Hull, fittings & equipment: 9,922 tons, 53.4 %
Fuel, ammunition & stores: 1,542 tons, 8.3 %
Miscellaneous weights: 4,000 tons, 21.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
96,871 lbs / 43,940 Kg = 2,126.1 x 4.5 " / 114 mm shells or 7.0 torpedoes
Stability (Unstable if below 1.00): 1.05
Metacentric height 5.2 ft / 1.6 m
Roll period: 17.7 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.05
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.623
Length to Beam Ratio: 5.99 : 1
'Natural speed' for length: 28.18 kts
Power going to wave formation at top speed: 50 %
Trim (Max stability = 0, Max steadiness = 100): 25
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 30.00 ft / 9.14 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 56.00 ft / 17.07 m
- Forecastle (20 %): 56.00 ft / 17.07 m
- Mid (50 %): 56.00 ft / 17.07 m
- Quarterdeck (15 %): 56.00 ft / 17.07 m
- Stern: 56.00 ft / 17.07 m
- Average freeboard: 56.00 ft / 17.07 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 46.1 %
- Above water (accommodation/working, high = better): 577.1 %
Waterplane Area: 43,008 Square feet or 3,996 Square metres
Displacement factor (Displacement / loading): 218 %
Structure weight / hull surface area: 107 lbs/sq ft or 520 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.72
- Longitudinal: 18.70
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Aircraft capacity: 7 (spread wings), 20 (folded wings) and 21 (boxed) Total 48

Radar Equipment:
Homing Beacon Type 290
HF/DF Type 291
Air Search Type 271

Misc Weight includes:
General Equipment 270 tons
Aircraft Equipment 1250 tons
Aircraft Armament 1000 tons
Two self-propelled lighters

Armour:
Belt is box protection for magazines

Ahoy Hood
I can't see how much I love it!!!

The Axis getting problems, with the allies

Nice drawing !

Could you make a top view of it ? It would help how very much.

Given that the RN has built the light fleet carriers already I'm not sure that something like Unicorn is needed. The other ships can easily serve as aircraft transports and repair ships. Not quite as good, but more flexible.

Sounds to me like a prototype for an amphibious assault carrier, with that proto-"well deck". Yes, I understand it's still with gantry cranes and not at water-level, but it seems to be a step towards that...

I'd like to see higher stability and steadiness, myself. 1.05 is just too low for my tastes.

At Brock, you are right. I think that's the intention behind this vessel.

Proto-assault carrier!! Come on guys!

The real Unicorn was designed to carry two self-propelled lighters and had two rear openings under the overhang to stow them. That is why the rear-end looks a little odd. I don't know whether these were carried but Norman Friedman's 'British Carrier Aviation' adds some interesting design history behind these ships.

Unicorn will be based in the Far East, the carrier fleet cannot operate without support, I've given quotes about servicability and crash rates elsewhere on this board and in becomes apparant that in wartime the carriers will need re-stocking and can't do all the big repair jobs themselves especially the ones which need the wings spread. I think this is WW's first dedicated carrier tender and is a neccessary price to pay to keep the fleet operating. Italian carriers don't go as far so don't need the logistical backup.

The light carriers are for patrol and fighter support roles, not repair. It's true I could have used the hull to build a Perseus but the Unicorn offers more space.

1.05 stability is low but it took some doing to acheive that. Since she'll mainly be anchored somewhere sheltered I'm not too concerned.

If it were my ship, I'd probably sacrifice a bit of the seakeeping (2.00!!!) for better stability. But that's me, and it IS an auxilliary, rather than a main-line warship.

Quoted

Originally posted by Hood
Proto-assault carrier!! Come on guys!

And I know very well that it's not; but seriously, it could play the part someday, with the proper conversion. After all, I think the USN converted an Essex to do that after WWII.

I harp mainly on the stability because I shoot for no lower than 1.10. I'll tolerate 1.05 on an auxiliary, but on a ship like this, I'll see 1.05 and say "redesign!"

I think I rebuild my Doorman I into an AU ship like that from Hood!! It's great and the Dutch fleet have needed.

Quoted

Originally posted by Brockpaine
I think the USN converted an Essex to do that after WWII.

Boxer, Princeton, and Valley Forge were 'converted' to LPHs, but that mostly consisted of not modernizing them at all (ie, no angled deck/ enclosed bow) and operating Helicopters for assault purposes. I don't think they carried any other kind of landing craft.