A plane with a wing effect in the ground to increase its autonomy on hydrogen

Low-flying ground-effect aircraft can provide emissions-free coastal transportation that goes much further and much faster than electric boats – without the need for FAA certification. So what happens when you add energy-dense hydrogen to the equation?

That’s the question Miami startup Sea Cheetah plans to address, with a plan to develop hydrogen-powered ocean skimmers and a hydrogen production, storage and refueling network in partnership with H3 Dynamics.

Airplane with wing effect in the ground: extreme efficiency and low cost

As we saw with the fossil fuel-powered Airfish-8 and the Regent Viceroy Seaglider battery-electric hydrofoil – not to mention Howard Hughes’ massive Spruce Goose “flying boat” and Soviet-era ekranoplans – There are some huge benefits to being detected when flying a plane at an extremely low altitude.

If you stay within the limits of your own wingspan relative to the surface, you get the usual lift effect of a moving wing: a high-pressure area below the wing and a low-pressure area above it. the wing where the air is forced to move faster. But because the air is briefly trapped in a small space under the wing and the surface, it compresses, increasing the pressure under the wing and generating additional lift.

This is the wing-in-ground effect (WiGE), and if you can optimize it by flying at an altitude of just 5% of your wingspan, it creates so much extra lift that you can fly 2.3 times further on an incredible flight. given energy source.

Given the severe range restrictions placed on batteries in electric planes and boats, you can see how there is a renewed interest in WiGE aircraft as the world struggles to decarbonize transportation.

The second key advantage, as we discussed in relation to Regent’s Seaglider, is that, according to these companies, they do not need to put their vehicles through the extremely expensive and time-consuming process of certification of the FAA to operate commercially in the United States. Indeed, the US Coast Guard has confirmed that it considers them vessels that should fall under its own maritime regulations.

This comes with its own set of operational problems: it will be extremely difficult, for example, for these craft to stop at high speed, or to give way to other vessels, as current laws require. But the certification process should be much faster and less expensive than going through the FAA, to the point where it fundamentally changes the economics at play.

In other words, companies like Regent and Sea Cheetah are banking on the ability to build and operate these WiGE ocean skimmers at a much lower cost than conventional aircraft. The value proposition for customers should therefore be enormous: much cheaper than air travel, much faster than a boat and much further on a battery charge than other zero-emission means of transport can take you.

Sea Cheetah wants to introduce hydrogen into the equation

The same goes for Sea Cheetah, an early-stage Florida startup looking to bring hydrogen into the mix for additional range and ultra-fast refueling.

It’s hard to know how seriously to take these early renderings; the company has not yet even managed to specify its proposed commercial offer. But the airframe here looks a lot like the Airfish-8: it has a large, rearward-swept wing with large surface area, upturned wingtips, and twin-fan propulsion blowing under a rear fin. supported by a V.

Unlike the Airfish, these large fans are ducted and probably electric, and the Sea Cheetah model has two huge pontoons on either side of the main fuselage. We assume that this is where the hydrogen in large volume and low mass will be stored.

Several variants are planned around the same general shape, including passenger transport and goods transport versions, as well as a rather impractical looking single-seater. All will likely use some sort of fly-by-wire system, which will automatically manage altitude and bank angles for safety reasons, while allowing captains simplified controls.

Yes, captains rather than pilots, assuming these are classified as ships rather than aircraft.

So how much better will hydrogen WiGEs be than battery electric WiGEs?

It’s really too early even to step outside the envelope and start speculating wildly about what effect switching to hydrogen will have on the range of this WiGE aircraft, compared to, say, the battery-electric Regent Viceroy Seaglider , which promises to take 12 passengers for distances of up to 180 miles (300 km) at a cruising speed of 180 mph (300 km/h).

For starters, we don’t know if Sea Cheetah plans to use compressed gas or cryogenic liquid hydrogen — or even if the company plans to burn it in combustion engines rather than running it through a fuel cell. fuel to extract electricity and drive an electric powertrain.

I will say this though: there is plenty of volume for fuel storage in these outrigger pontoons, so it is not unreasonable to assume that if they are filled with compressed hydrogen gas, the Sea Cheetah might be able to to triple the range of an equivalent-sized Seaglider – and if it were liquid hydrogen, you might be able to double that figure to get super-impressive range figures.

On the other hand, if a passenger is going that far, he or she might very well choose to fly, simply to reduce travel time; airliners sail more than three times faster than the Viceroy.

And as hydrogen fuel becomes better understood and tested for safety in aviation, it may well become a relatively simple range-extending technology that a company like Regent could add to its own designs.

Sea Cheetah therefore may not have a huge commercial advantage to assert in direct competition with this much more established rival, which has already flown prototypes and is preparing a full-scale machine for flight testing .

So this one is a little undercooked in its current form, and these cheesy renderings won’t do much for the credibility of the companies involved. But it’s an interesting idea to look into in any case, and we’ll keep an eye out for updates, especially when Sea Cheetah is ready to start releasing some numbers to dig into.

Source: Sea Cheetah via H3 Dynamics (PDF press release)