WesWorld

This design is intended to provide scouting and logistic support for submarine flotillas, not so much for commerce raiding, but for sort of a guerilla war at sea. It is intended that the ship sails to a remote island to establish a base, and the patrols of the seaplanes find targets for the submarines or give warning of the approach of enemy warships. Once established, the base can support the operation of large multi-engined seaplanes to extend patrols over a wide area.
Conversely, the ship can hide in remote seas, returning to more heavily-travelled waters at times of her choosing, to support a submarine operation with her aircraft, and then hiding again.

Russian Seaplane Tender, laid down 1924

Length, 120.0 m x Beam, 15.6 m x Depth, 5.0 m
4718 tonnes normal displacement (3364 tonnes standard)

Main battery: 4 x 13.0-cm (2 x 2)
Secondary battery: 4 x 7.6-cm
AA battery: 16 x 3.7-cm
Light battery: 4 x 1.3-cm

Weight of broadside: 158 kg

Hull unarmored

Battery armor:
Main, 2.5 cm / secondary, 2.5 cm shields
AA, 2.5 cm shields

Aircraft - 10 Seaplanes, 1 Catapult, 1 Crane (1 starboard, 1 port)

Cargo - 1,250 metric tons 3,300 GRT

Maximum speed for 7449 shaft kw = 20.00 knots
Approximate cruising radius, 15100 nm / 15 knots

Typical complement: 285-370


Estimated cost, $2.421 million (£605,000)

Remarks:

Ship has slow, easy roll; a good, steady gun platform.

Excellent seaboat; comfortable and able to fight her guns
in the heaviest weather.

Magazines and engineering spaces are roomy, with superior
watertight subdivision.


Distribution of weights:
Percent
normal
displacement:

Armament ......................... 43 tonnes = 1 pct
Armor, total ..................... 33 tonnes = 1 pct

Armament 33 tonnes = 1 pct

Machinery ........................ 329 tonnes = 7 pct
Hull and fittings; equipment ..... 1335 tonnes = 28 pct
Fuel, ammunition, stores ......... 1478 tonnes = 31 pct
Miscellaneous weights ............ 1500 tonnes = 32 pct
-----
4718 tonnes = 100 pct

Estimated metacentric height, 0.7 m

Displacement summary:

Light ship: 3240 tonnes
Standard displacement: 3364 tonnes
Normal service: 4718 tonnes
Full load: 5783 tonnes

Loading submergence 1186 tonnes/metre

+++++++++++++++++++++++++


Estimated overall survivability and seakeeping ability:

Relative margin of stability: 1.11

Shellfire needed to sink: 3305 kg = 108.5 x 13.0-cm shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not counting critical hits)

Torpedoes needed to sink: 1.9
(Approximates number of 'typical'
torpedo hits needed to sink ship)

Relative steadiness as gun platform, 70 percent
(50 percent is 'average')

Relative rocking effect from firing to beam, 0.12

Relative quality as a seaboat: 1.51

+++++++++++++++++++++++++


Hull form characteristics:

Block coefficient: 0.50
Sharpness coefficient: 0.36
Hull speed coefficient 'M' = 7.17
'Natural speed' for length = 19.8 knots
Power going to wave formation
at top speed: 45 percent


Estimated hull characteristics and strength:

Relative underwater volume absorbed by
magazines and engineering spaces: 65 percent

Relative accommodation and working space: 100 percent


Displacement factor: 186 percent
(Displacement relative to loading factors)


Relative cross-sectional hull strength: 0.98
(Structure weight per square
metre of hull surface: 341 kg)

Relative longitudinal hull strength: 1.21
(for 3.60 m average freeboard;
freeboard adjustment -0.37 m)

Relative composite hull strength: 1.00

+++++++++++++++++++++++++


[Machine-readable parameters: Spring Style v. 1.2.1]

393.60 x 51.17 x 16.40; 11.81 -- Dimensions
0.50 -- Block coefficient
1924 -- Year laid down
20.00 / 15100 / 15.00; Oil-fired turbine or equivalent -- Speed / radius / cruise
1500 tons -- Miscellaneous weights
++++++++++
4 x 5.12; 2; 0 -- Main battery; turrets; superfiring
:
4 x 2.99; 0 -- Secondary battery; turrets
Gun-shields
:
16 x 1.46 -- Tertiary (QF/AA) battery
Gun-shields
:
4 x 0.51 -- Fourth (light) battery
0 -- No torpedo armament
++++++++++
0.00 -- No belt armor
0.00 / 0.00 -- Deck / CT
0.98 / 0.98 / 0.98 / 0.00 -- Battery armor


(Note: For portability, values are stored in Anglo-American units)


+++++++++++++++++++++++++++++++++++++++++++++++++++++++

A nice design, assuming the ship's dimensions are large enough to handle the aircraft and facilities.

Interesting ideas, AdmK. :o) And an interesting design. Looking at the sheet alone it seems quite reasonable.

On the other hand I fear you vessel is too small and will lack sufficent deckspace to operate 10 floatplanes. More so if one considers the place needed for all those guns...

Anyway, an interesting concept. It might need a larger ship but that´s it...

Cheers,

HoOmAn

Orlitsa carried up to 5 on 91.5m length and 12m beam, along with 8 75mm guns.

http://www.hazegray.org/navhist/carriers/russia.htm#orli

I'm thinking the extra 28.5m length and 3.6m beam might allow an elevator that can take a 12m x 8m aircraft.

Have the cratapult on the port beam, the elevator in the starboard, and the crane aft of the elevator, with the arc running over the elevator and the catapult.

Conversely, lose the catapult and add a second crane.

India's Palk Bay is a somewhat larger design (in the minds of some, too large), but some of that extra space is taken up by scientific and surveying facilities.

I'll have to do a sketch of her...could be interesting.

Palk Bay, laid down 1921

Length, 500 ft x Beam, 65.0 ft x Depth, 16.0 ft
7874 tons normal displacement (6819 tons standard)

Main battery: 4 x 4.1-inch
Secondary battery: 8 x 1.4-inch
AA battery: 6 x 0.6-inch

Weight of broadside: 149 lbs

Hull unarmored

Battery armor:
Main, 2.0" shields / secondary, 1.0" shields
AA, 1.0" shields

Maximum speed for 12492 shp = 19.72 knots
Approximate cruising radius, 14000 nm / 12 kts

Typical complement: 418-543


Estimated cost, $3.142 million (£786,000)

Remarks:

Ship has slow, easy roll; a good, steady gun platform.

Good seaboat; rides out heavy weather easily.

Magazines and engineering spaces are roomy, with superior
watertight subdivision.

Ship is roomy, with superior accommodation and working space.

Aviation Facilities: 10 floatplanes, 2 catapults, 2 cranes, hangar, workshop

Scientific/Surveying facilities: 200 t of miscellaneous weight

Cargo capacity: 1500 t




Distribution of weights:
Percent
normal
displacement:

Armament ......................... 19 tons = 0 pct
Armor, total ..................... 15 tons = 0 pct

Armament 15 tons = 0 pct

Machinery ........................ 430 tons = 5 pct
Hull and fittings; equipment ..... 4185 tons = 53 pct
Fuel, ammunition, stores ......... 1226 tons = 16 pct
Miscellaneous weights ............ 2000 tons = 25 pct
-----
7874 tons = 100 pct

Estimated metacentric height, 3.1 ft

Displacement summary:

Light ship: 6649 tons
Standard displacement: 6819 tons
Normal service: 7874 tons
Full load: 8687 tons

Loading submergence 607 tons/foot

+++++++++++++++++++++++++


Estimated overall survivability and seakeeping ability:

Relative margin of stability: 1.10

Shellfire needed to sink: 19042 lbs = 552.6 x 4.1-inch shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not counting critical hits)

Torpedoes needed to sink: 3.6
(Approximates number of 'typical'
torpedo hits needed to sink ship)

Relative steadiness as gun platform, 81 percent
(50 percent is 'average')

Relative rocking effect from firing to beam, 0.02

Relative quality as a seaboat: 1.47

+++++++++++++++++++++++++


Hull form characteristics:

Block coefficient: 0.53
Sharpness coefficient: 0.37
Hull speed coefficient 'M' = 7.69
'Natural speed' for length = 22.4 knots
Power going to wave formation
at top speed: 38 percent


Estimated hull characteristics and strength:

Relative underwater volume absorbed by
magazines and engineering spaces: 48 percent

Relative accommodation and working space: 155 percent


Displacement factor: 260 percent
(Displacement relative to loading factors)


Relative cross-sectional hull strength: 1.75
(Structure weight per square
foot of hull surface: 138 lbs)

Relative longitudinal hull strength: 1.84
(for 16.0 ft average freeboard;
freeboard adjustment +1.6 ft)

Relative composite hull strength: 1.76

+++++++++++++++++++++++++


[Machine-readable parameters: Spring Style v. 1.2.1]

500.00 x 65.00 x 16.00; 16.00 -- Dimensions
0.53 -- Block coefficient
1921 -- Year laid down
19.72 / 14000 / 12.00; Oil-fired turbine or equivalent -- Speed / radius / cruise
2000 tons -- Miscellaneous weights
++++++++++
4 x 4.10; 0 -- Main battery; turrets
Central positioning of guns
Gun-shields
:
8 x 1.40; 0 -- Secondary battery; turrets
Gun-shields
:
6 x 0.60 -- Tertiary (QF/AA) battery
Gun-shields
:
0 -- No fourth (light) battery
0 -- No torpedo armament
++++++++++
0.00 -- No belt armor
0.00 / 0.00 -- Deck / CT
2.00 / 1.00 / 1.00 / 0.00 -- Battery armor


+++++++++++++++++++++++++++++++++++++++++++++++++++++++

Shouldn´t a seaplane tender be build with those CV rules in mind that define hangar space?

I think they should.

What do you guys think?

HoOmAn

I think so, and as far as I know, I've done so.

I've allowed 300 t of miscellaneous weight for the ten aircraft (versus the 250 required), and the ship's area supposedly allows for 43 aircraft (!). Am I missing additional rules?

The trick now is to arrange superstructure, deck, weapons, cranes, catapults, and elevators. Just a simple outline of hull and plane tells me that it'll be a challenge.

Quoted

Shouldn´t a seaplane tender be build with those CV rules in mind that define hangar space?

I agree.

And here they are:
"Design the ship as you normally would. Put in as much
'miscellaneous weight' as you can - that will usually
determine how big an airgroup your CV can carry. Now,
get out your pocket calculator. You'll make two pretty simple
calculations, each of which gives a possible airgroup limit.

1) Take the square root of miscellaneous weight; e.g., if
miscellaneous weight is 10,000 tons, the weight-based limit
for your carrier is 100 aircraft. (In addition, allow at
least 25 tons per aircraft, i.e., if miscellaneous weight
is just 100 tons, your ship can carry 4 planes, not 10.)

2) Multiply length x beam (both waterline) and divide by 750;
e.g., if your CV is 900 ft x 100 ft, the space limit is 120
aircraft.

For the metric gang, divide by 70 instead; if your CV is
280 metres x 30 metres, the size limit is also 120 aircraft.

Use waterline dimensions (if available), NOT flight deck
dimensions; they can vary a lot more, and we want a
consistant rule.

Your carrier's airgroup is whichever number is LOWER.
So in the example above, your CV has an airgroup of 100
aircraft. (That is for WW II or earlier planes. For postwar
CVs with jets, I'd estimate about 2/3 of the airgroup
calculated by this method.) Usually, the weight rule gives
a lower number of planes and thus sets the limit; the size
limit will usually apply to CVEs converted from merchant
ships with a great deal of miscellaneous weight."

So taking the 1924 Seaplane Carrier as an example, she reserves 250 tons displacement for aircraft and aviation facilities, allowing 10 aircraft by that measure.

Now for hangar space, multiply length and beam, and divide by 70. 120 x 15.6 = 1,872.

1,872 / 70 = 26.7.

So by both measures, she can handle 10 aircraft.

If 6 aircraft can fit below, and one is carried on the catapult, that leaves 3 to be carried on the deck. The aircraft I have in mind are 3m high. Since she has 3.6m freeboard, I can have the main deck ~0.5m above the waterline and still have a little headroom. Putting the elevator ~45m from the bow, I'll stow aircraft aft, and supplies forward, using the elevator and crane for both.

I'll be trying to cram them all inside, but I've got more space to work with.

I was under the impression that hangars were considered to be on top of the freeboard, provided they weren't armored or important from a structural sense. You might have more room than you think.

J

it wasn´t my intention to say you gusy haven´t build your seaplane tenders with those rules in mind - I just wanted to be sure that there is no other rule of thumb around for seaplane carriers.

AdmK, you wrote:

"The aircraft I have in mind are 3m high."

May I dare to ask which plane you´ve in mind? I´ve browsed through many sourced but all floatplanes I found had a high of min. ~3,5m and flaying boats were even higher.

I agree that ~0,5m headway is a minimum for a hangar. You´ll need some tools and gear inside to handle engines if you need to replace them etc.

Cheers,

HoOmAn

Understood, I just wanted to make sure we were talking about the same rules. Using the word "hangar" kinda threw me off.

J

Here's the Wright F3W1 Apache:

http://www.csd.uwo.ca/~pettypi/elevon/ba…other/f3w1.html

Technical data-
Type:
Single-seat shipboard biplane fighter.
Powerplant:
One 425 hp Pratt & Whitney R-1340B Wasp nine-cylinder radial piston engine.
Fuel capacity:
Internal fuel capacity: 178 litres.
Performance:
Maximum speed: 261 km/h at sea level. Service ceiling: 10,180 m. Landing speed: 87 km/h.
Dimensions:
Wingspan: 8.33 m. Length: 6.73 m. Height: 2.59 m. Wing area: 19.97 m2.
Weights:
Empty weight: 641 kg. Take-off weight: 965 kg.

The Italian FBA of World War I:
http://www.worldwar1.com/dbc/fba.htm

Dimensions:
Length: 10.1m
Height: 3,33m
Empty Weight 955kg
Loaded Weight 1480kg
Maximum Speed 145 kph
Wing Span 14,50m


The DHC-2 Beaver, a monoplane:

http://www.geocities.com/CapeCanaveral/Lab/7146/beaver.html

Engine Pratt & Whitney R-985 AN-6B or AN-14B Wasp Jr.
Dimensions:
Wing span 14.6 m
Length 9.2 m
Wing area 23.2 sq m
Height 2.7 m (wheels), 2.9 m (skis)


They're not exactly what I've in mind, but there they are.

Quoted

Originally posted by AdmKuznetsov
If 6 aircraft can fit below, and one is carried on the catapult, that leaves 3 to be carried on the deck. The aircraft I have in mind are 3m high. Since she has 3.6m freeboard, I can have the main deck ~0.5m above the waterline and still have a little headroom. Putting the elevator ~45m from the bow, I'll stow aircraft aft, and supplies forward, using the elevator and crane for both.

I recommend you treat the hangar as being placed on top of the freeboard, and not part of the hullgirder - that was the norm for by far the majority of the seaplane-carriers, and for very many aircraft-carriers also. Having the hangar-deck only 0.5 metres above the waterline is in fact quite hazardous if you get flooding.

SR Palk Bay, adjusted to have a 20' freeboard. The below-decks hangar is the area lacking portholes. Those lines on the flight deck are trolley tracks for moving the planes around...

Nice drawing rocky!