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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)

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

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

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.

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.

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

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

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.

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

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

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.

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.

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