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Comment by elihu | Hacker News Reader

Whatever happened to large sea planes? I imagine they were phased out because they were too expensive, unsafe, or for some other logistical reason, but it seems like they would still be practical for some purposes.

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The question isn't why they were phased out; it's why they existed in the first place.

They enabled aircraft to make fuel stops at undeveloped supply caches that happened to have a functioning seaport, but no long runway. This was necessary both because of the scarcity of paved runways at the time, and because the short ranges of the time necessitated multiple fuel stops in order to make long-haul journeys.

Once those necessities faded, both because of the build-out of airstrips worldwide (e.g. paved runways in Sri Lanka) and because of improving aircraft technology (no need to stop in Sumatra on the way from Java to Sri Lanka), there was no reason to go with an aircraft that couldn't land inland and had its aerodynamic properties constrained by the need for seaworthiness.

There's probabally other limitations, but as I understand it one of the limiting factors is takeoff and landing speed. Even on a good day and in a still harbor, water is pretty bumpy, which means you need to be out of it at a pretty low speed. This leads to all sorts of tradeoffs elsewhere in the airplane design (mostly, again - as I understand it, in wing design) that hamper the airplane in other ways.

In the end, it's more practical to deal with the problem of finding an airport (after all, there are a lot of airports) than to solve the other problems of making a large sea plane.

Low take off speed means you need a lower wing loading and that limits your max speed and ultimate range. Perversely higher landing speeds are safer to boot.

Also read an interview with a pilot that flew Clippers. He said maintence was nightmarish due to salt water. And also being able to land in water sounds good until you factor in weather and the need to eventually dock.

Has anyone experimented with hydrofoils to take the plane out of the water and have a higher take-off speed?

Edit: answering my own question https://aviation.stackexchange.com/questions/24526/has-anyon...

I think passenger sea planes faded as airports were built and faster piston, later jet aircraft became available.

There are still some large sea planes used for fire fighting service and a few airworthy PBY Catalina's.

See

https://en.wikipedia.org/wiki/Canadair_CL-415

and

https://en.wikipedia.org/wiki/Consolidated_PBY_Catalina

Catalina's were heavily used in WWII for scouting and rescue in the Pacific. There is a partial documentary of some guys flying a Catalina around the world which was cut short when they were forced to abandon it in Saudi Arabia.

Catalinas were also used during the war as part of the Australia-England air link, cross the Indian Ocean from Perth to Ceylon.

https://www.qantas.com/travel/airlines/history-catalinas/glo...

I had never heard of that route.

> The flying boats, travelling at about 200km/h, would take an average of 28 hours to complete the journey, but up to 32 hours nine minutes when winds were unfavorable.

Description of flying those was, they were docile but didn't have power assisted controls. Flying one for 30 hours in shifts even must have been brutal.

The Japanese navy operates the US-2 for search and rescue. Its wingspan is smaller and its maximum range is less than the Pan Am Clippers, but can carry more weight and is much faster.

https://en.wikipedia.org/wiki/ShinMaywa_US-2

During ww2 thousands of new airports were built all over the world, including in very remote areas such as various pacific atolls where flying boats had been the only alternative pre-war. Once the war ended many of these became available for refueling stops, and as land-based aircraft often had a lower seat cost/distance as well as higher cruising speed they took over from flying boats.

> or for some other logistical reason

The development of a system of airports (+ new planes that could fly trans-oceanic flights without stop-overs in far-flung locations).

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