A Life On The Ocean Wave

Are sea-based aircraft ready for a comeback? The latest in a series of new seaplane ventures made a splash at the Oshkosh air show, where Catalina Aircraft of Florida announced plans to restart production of the classic Consolidated PBY Catalina flying boat, with new turbine engines (likely the GE Catalyst), aimed at commercial and military markets.

The key to any chance that the Next Generation Amphibious Aircraft (NGAA) might have is that, in a minor historical fluke, the US Navy-developed PBY acquired a US type certificate when, just after WW2, Air France needed aircraft to connect French Caribbean territories. The aircraft were modified by Canadian Vickers Ltd, and the TC has since been passed from one owner to another before ending up with the Florida company

Note that the image is in full accordance with the unwritten rule of commercial seaplane travel posters…

… possibly explaining why sometimes people talk about the “romance” of flying-boat travel. A modern academic would call it “problematic Orientalism” and could write a PhD dissertation on these five examples alone.

Catalina Aircraft is not the only company with plans to revive an elderly amphib. Amphibian Aerospace Industries (AAI) of Darwin, Australia, owns the TC for the Grumman G-111, the commercial version of the HU-16 Albatross. AAI announced last December that it had acquired an airplane for modification and has been picking up investors here and there.

More radical projects include Norway’s all-electric, nine-passenger Elfly and the 19-passenger Jekta from Switzerland. Viking Aircraft in Canada is continuing to upgrade older CL-415 water-bombers to the newer EAF standard, but has yet to make the jump to new-production CL-515 versions. Again, Viking is the classic entrepreneurial ticket-holder, having acquired the rights to the de Havilland Canada and Canadair propeller ranges from Bombardier.

Not to be left out, the Pentagon has had two sea-based aircraft efforts under way, which may not be a lot, but is two more than the DoD has had since the last HU-16s were replaced by helicopters in the 1960s. The USAF Special Operations Command has been looking at a version of the MC-130J fitted with massive pontoon floats, but after some early excitement the project hit unspecified snags and has been delayed. One of those snags should be “it’s really ugly”.

It’s a rehash of a concept floated (so to speak) in the mid-1990s, and it may be an illustration of the reasons why large seaplanes have mostly had hulls rather than floats. Together with their bridge-like supporting structure, the floats are heavy and draggy and play hell with the payload and range, and their bows are far below the thrust line but behind the nose. It looks as if the pilot will have to be careful pouring on the power or risk burying a float.

Then there’s DARPA’s mildly insane LibertyLifter concept for a wing-in-ground-effect (WIG) craft with a payload similar to a C-17, but with far lower construction costs. (STOL high-speed military cargo airplanes are complicated beasts.) “Liberty” is a deliberate echo of “Liberty ships” and the idea is something designed and built more like a ship than an airplane, and that can spend extended time sitting on the ocean, but can nevertheless fly at 10,000 feet, to avoid detouring around islands.

GA-ASI won one definition contract in a team with MAPC, the maritime research company that introduced DARPA to the idea, and is working on something that looks like a cross between 12-engine Dornier’s Do X of the 1920s and General Italo Balbo’s twin-hull Savoia boats from 1930. Boeing’s Aurora won the other contract with a smaller version of the Phantom Works’ impressively barmy Pelican design from 2003.

One hopes someone involved has delved into the history of Russia’s ekranoplans and read and studied DARPA’s own extensive reports from the 1990s. Short version, to paraphrase Wellington: “I don’t know what the sight of these things will do to the enemy, but by God, sir, they frighten me.” To take a few examples: a WIG in level flight over a rolling sea will constantly change its lift-to-drag ratio, which is dependent on height above the surface. Regular seaplanes go through some stability changes as they transition from floating to planing and from planing to flight; the transition from WIG flight to free flight is… positively interesting. (The Russians reportedly got one of their vehicle to 100 meters altitude and afterwards, having done their laundry, were very careful not to get caught in that situation again.)

Another issue is strength and weight. Building a WIG strong enough to survive a wave slap adds weight and offsets the aerodynamic advantage of in-ground-effect flight. Avoiding wave slap means flying higher with less ground-effect benefit and… hey, if we fly above 10,000 feet all the time we could save a lot of weight. We could call it a.. a seaplane.

“Seaplane” is actually a bit of a misnomer. The French hydravion is better because we’re really talking about waterplanes, and aside from the ShinMaywa designs (which have become Internet video stars), you don’t want to land an airplane on the open sea. If you look at the Imperial Airways routes to South Africa and Australia/NZ, a surprising amount was overland. During the non-combatant evacuation operations in Sudan earlier this year, I was reminded that Khartoum was a stop on the South Africa route, using the Nile as a runway. The classic flying-boat bases of the 1930s like Southampton, New York, and Foynes in Ireland (where Irish coffee was invented to restore airsickness-ravaged zombie passengers to life) were many miles from open ocean.

There are lakes, rivers, bays and even reservoirs all over the place. And you can look at parts of the West Pacific and, from a landplane viewpoint, they are unpromising. Irregular mountaintops jutting from the sea and nowhere to put a runway without terraforming an island environment. Now put on your hydravion spectacles – sheltered water everywhere, and the number of suitable locations goes up if your aircraft is also STOL. If you’re talking about dispersed military operations, too, you stop worrying about trucks on narrow twisty roads and think about boats.

And have you ever tried to crater an estuary, lagoon or bay with a missile warhead? Exercise in frustration.

Finally – designing or modifying airplanes to operate in that environment might be easier than we think. There was a lot of creativity in waterplane design in the 1940s and 1950s, which sadly coincided with a loss of interest in things that weren’t supersonic and nuclear-capable. For example, what was wrong with hydro-skis? One big problem was that the vibration was intolerable for the… pilot….


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