Seaplanes & Submarines

[copeab]

Originally Posted by ak_aramis

If your goal with subs is avoiding weather, then it's pretty safe to assume a need for 50m depth, plus 5m above surface, as needed for snorkel, so a safety margin of ±5m for 60m snorkel, of which 10m is probably rigid.

Most ocean going subs of this era (as compared to coastal subs) had a safe diving depth of around 100m or yards, which should be sufficient. Even coastal subs could usually make 75m.

[Anaraxes]

Storms are bad for aircraft, too. In this era, it's not quite so easy to fly over storms or fronts as it is with pressurized jets. On the bright side (for ruining surface ships, that is), a water world with small islands may well generate bigger waves on the larger oceans, which wouldn't matter to subs or planes.

Shipping costs will be higher than in our world. A surface ship is mostly cargo volume. A submarine version of that ship has to be bigger yet, to allow for the buoyancy tanks, and needs a pressure hull. I'm not sure if an air supply or plant takes up significant space.

Submerged speed of a WW2 sub is maybe half that of the surface speed. They spent almost all their time on the surface. So the cargo subs are likely diving just to escape storms. (The storms are presumably also a threat to a surfaced sub.)

[copeab]

Originally Posted by Anaraxes

Storms are bad for aircraft, too. In this era, it's not quite so easy to fly over storms or fronts as it is with pressurized jets. On the bright side (for ruining surface ships, that is), a water world with small islands may well generate bigger waves on the larger oceans, which wouldn't matter to subs or planes.

Another option is for the plane to set down in a sheltered lagoon, beach the plane and wait until the storm passes.

Submerged speed of a WW2 sub is maybe half that of the surface speed. They spent almost all their time on the surface. So the cargo subs are likely diving just to escape storms. (The storms are presumably also a threat to a surfaced sub.)

Although ... in 1938 Japan launched a test sub that made 13 knots on the surface and 21 knots submerged using diesel electric engines. Two classes were based on it but few were built, but both classes were faster underwater than surfaced.

[sambudak]

Are diridgibles out then? Could they attain a high enough altitude to be safe enough from the weather?

[copeab]

Originally Posted by sambudak

Are diridgibles out then? Could they attain a high enough altitude to be safe enough from the weather?

I have reluctantly decided not to use airships, although I can be talked into allowing autogyros.

[Kale]

Originally Posted by ak_aramis

If, instead, you go with a nuke, you can get electrolysis, don't need batteries (which were, at the time, lead-acid, heavy as heck, low energy density), and can cruise for months, or even years. And, to be honest, it's only a decade past your envisaged era.

Captain Nemo's Nautilus was hinted to be nuclear powered. Perhaps an 'early' breakthrough could be handwaved in.

Originally Posted by copeab

I have reluctantly decided not to use airships, although I can be talked into allowing autogyros.

If storms are any kind of issue airships would be a bad idea. Most historical examples were lost due to weather issues.
Autogyros would be handy for landing somewhat inland if launched from a sub offshore, although you still need a substantial bit of cleared road or the like to land or take off. Basically the only thing they would offer over a seaplane would be the shorter takeoff and landing requirements. Their range would be shorter than a seaplane but I could see a small one being carried for quick jaunts inland off a sub parked in a bay or lagoon. Again this would depend on available landing area.

[Fred Brackin]

Originally Posted by sambudak

Are diridgibles out then? Could they attain a high enough altitude to be safe enough from the weather?

The combination of light structure and large surface area makes high winds terribly dangerous to rigid airships.

If you look at the history of dirigibles between WWI and II you've got only a few retirements, one or two major fires and almost every other one was lost to weather.

They can go high but are limited by crews and engines much the same as winged craft. It is also very complex for them to gain and lose altitude.

By the time you're ready to build the very large flying boats such as the Pan Am Clipper and similar craft dirigibles just don't have many advantages over winged planes.

The primary advantage they do is the ability to travel at very low speeds with little energy expenditure. That's why advertising blimps stay in business long after the other airships have gone away.

The last applications to go away before advertising were maritime patrol, convoy escort and radar patrol. Long slow flights all of them.

Rigid airships don't have any particular advantages in travelling from point A to point B and if weather is bad enough to regularly endanger large surface ships it's gotten rid or airships before that.

[Anaraxes]

Could {dirigibles} attain a high enough altitude to be safe enough from the weather?

Probably not with WW2 tech. At least according to Wikipedia, the record altitude for rigid airship was 24,000 feet (1917). They claim a practical limit for commercial operation of around 3000 feet (hydrogen-filled passenger airship record of 5500 feet for the Graf Zeppelin), 8000 for pressure ships.

Even modern jets fly around storms, rather than over them. Cumulonimbus clouds can reach 60,000 feet; severe thunderstorms are at least 30-35,000 feet tall. FAA advice is to clear the top of a thunderstorm by at least 1,000 feet for every 10 knots of wind speed at the top of the storm, which can easily be 50 knots or more; maximum altitude of commercial jets like a 747 or 777 is about 45,000 feet. You fly over rain, or clouds that block visibility, but not ship-threatening storms.

There are a number of current research programs or prototype development for LTA ships that can fly up to 60-70,000 feet, usually for surveillance or research purposes as a sort of cheaper standin for satellite observation.

[copeab]

Originally Posted by Kale

Captain Nemo's Nautilus was hinted to be nuclear powered. Perhaps an 'early' breakthrough could be handwaved in.

I think my wrist will be broken just handwaving out land-based planes and surface ships ;)

Autogyros would be handy for landing somewhat inland if launched from a sub offshore, although you still need a substantial bit of cleared road or the like to land or take off.

Actually, you don't. A powered jump start of the rotor (using power from the engine) could result in a near vertical takeoff. And it was possible to land with a very short roll by "stalling" the autogyro, especially into a headwind.

While a sub could probably launch an autogyro, recovering it would be a problem.

[jason taylor]

Originally Posted by copeab

Submarines did sink other submarines in WWII, although I'm not sure if both were submerged at the time.

According to TV Tropes there was only one time when both were submerged.

The Bowfin, got three in succession I believe but they were caught on the surface.