I believe ekranoplans will come back. The biggest issue the Soviets faced with their ekranoplans should be addressable with modern technology. That issue is stability. The problem is when you have waves under the wings they create different pressures and air currents under the wings, which makes the airframe unstable and may cause it to flip to the side or dive into the water. That is why the soviet ekranoplans had enormous tails.
However, this is something that should be addressable nowadays. One should be able to design a system where a ladar scans the water surface ahead and a computer uses that information and various control surfaces on the wings to compensate for waves below the wings. It sounds very complex but it should be doable.
Of course, the ocean can produce waves that are much too big for ekranoplans regardless of what stability technology one uses. But another modern advantage is that we can now know the state of the ocean everywhere at any time, so a solution for this is that the ekranoplans simply should avoid areas with large waves.
These vehicles would be perfect for fast transport if fuel prices were lower. The problem is that with today's high fuel prices, the demand for fast but energy inefficient transport is not enough to justify researching new aircraft types.
But this also has good military potential. It is fast and yet it can carry much more weight than an airplane. It can carry enough armor to make it immune to anti-air missiles, yet it is fast enough to escape anti-ship missiles. It can carry all the active anti-missile technology of a warship, but not be a slow sitting duck like a warship. It can carry a powerful ship borne radar, yet move together with fighter formations. It can carry attack troops to beaches at high speeds and then land in the water right in front of the beach.
Stability was also the limiting factor in flying wings back in the 50s and 60s, and the B2 proved that electronics can solve that problem. So stability seems like a solved problem to me.
Military use seems like the most obvious use for these vehicles to me. One of the biggest obstacles to an invasion of the United States for countries that aren't Canada or Mexico, is transporting a large enough forces across the ocean rapidly enough. Even if China (for example,) were to defeat the US fleet, They'd still have a heck of a logistical problem getting troops on the US mainland. A super fact freighter would solve that problem. and conceivably enable a flanking attack. The same would be true of any transoceanic war.
If you're afraid that China will invade the USA then you should study history a bit more. That doesn't mean that it can not happen at all but the chances are slim. The USA invading China probably has much higher chance of happening.
Of all the countries on Earth, there are only really two that could mount a full scale invasion against the United States and hope to win, China and Russia. Neither is likely, but it would have to be one of them for us to consider this scenario.
Also, you're right that China invading the US is probably very unlikely, but probably not for any historical reasons. China and the US rely on each other too much as trading partners at this juncture for a full scale war to be wise. Also, much of China's wealth is wrapped up in US debt, a war with the US would endanger their savings. The biggest contention between the US and China at this point is the independence of Taiwan, which could lead to war, but not a mainland invasion of the United States.
Then again, if you do look at history, Japan's attack on Pearl Harbor was motivated by passive aggressive attempts by the United States to 'contain' Japan during the Second World War. Specifically, the United States blocked the import of oil to Japan. If the United States tries too hard to contain China, China might feel compelled to break the US's hold on the Pacific. This isn't like though, and a full scale war coming of it is also unlikely.
> Of course, the ocean can produce waves that are much too big for ekranoplans regardless of what stability technology one uses.
What about rogue waves? Ekranoplans would have to be able to detect and fly over rogue waves and ocean storm swells. Rogue waves don't occur that often, but ocean storm swells do. As you point out, it routine now to detect storm swell conditions.
> It can carry enough armor to make it immune to anti-air missiles, yet it is fast enough to escape anti-ship missiles.
I don't think it would be hard to redesign anti-ship missiles or AA missiles used in look-down/shoot-down systems to negate any evasion advantage ekranoplans would have.
Some Ekranoplans (like the Lun mentioned in the article) have the ability to fly above the ground effect zone, though less efficiently.
If rogue waves (or other rough sea) can be spotted far enough ahead, the plane could increase altitude over brief rough spots, settling back on to its ground effect cushion once calmer waters were reached.
Because it's travelling so much faster than surface waves, the lidar (or whatever scanning system) would only have to consider a relatively narrow field of view in front of the craft.
It also seems like more advanced fly-by-wire/computerized flight assistance technology could make them less prone to pilot error (e.g. banking too sharply, pulling back on the stick too hard and causing the ground-effect to dissipate, etc).
We don't even remotely know the state of the ocean everywhere. Even in well traveled sea lanes there are gaps of several hours between weather satellite passes.
Fuel prices aren't that high right now. GEVs are slightly more fuel efficient that regular aircraft but not enough to overcome all the disadvantages.
There's no way you can mount enough armor to provide immunity against modern missiles while still leaving useful cargo capacity. Armor is too heavy.
So nearly zero potential.
The Boeing Pelican was a proposed ground-effect aircraft for heavy lift over long distances. It exploited the same aerodynamic effect but was optimized for cargo rather than as a weapons platform.
So what strikes me as more interesting is the potential for this as an alternative to conventional ferries and cargo runs for short haul stuff or vs trains up and down the coasts.
A miami-bahamas GEV plane could make the trip in 20 minutes vs 2 hours for a "high speed" catamaran ferry. But if you used it to ferry cargo from Miami - DC (traditional flight is 2.5 hours) but you could shuttle cargo in 4 hours perhaps (though i'm sure much more expensive than traditional cargo ships) but faster than the 12-18 hours a train takes or a truck takes.
It occurred to me that the increased efficiency might find these a niche as rapid trans-oceanic transport, but 15 feet from the surface is too low for waves likely to be encountered in ocean storms.
Another problem would be all kinds of boats and other planes in ground effect. The see is two dimensional, unlike airspace, which makes it quite a bit harder for a fast moving Ekranoplan or similar to weave through slower traffic. It would be a continuous game of frogger with the occasional direct hit likely resulting in loss of both vehicles. The sea is not a very forgiving environment and avoiding collisions at the slow speeds normally used on the water is already hard enough. Imagine a plane in ground effect having to cross a busy shipping lane in bad weather.
Planes colliding is very rare but it does happen occasionally even though they have 3 dimensions to work with. If you'd compress that traffic to two dimensions and then add slow moving commercial vessels, sail boats and weather into the mix I fear it won't end well.
At some considerable increase in fuel consumption Ekranoplans can 'jump' up a bit, keep it up long enough and you won't have enough fuel to reach the destination. This is also how they make turns. There are also hybrids that can fly at some altitude like a normal plane that just exploit the ground effect to increase efficiency. As opposed to those that are almost always in ground effect.
These are super interesting craft, you can easily spend a week just reading about them.
Mid-air collisions are rare first and foremost because most flights happen in controlled airspace with assigned flight levels, routes and ATC monitoring the flights on radar (and TCAS as a last resort for collision avoidance). Mid-air collisions are far more common in uncontrolled airspace where light airplanes fly.
So the answer would be to provide controlled areas for the ekranoplans to travel and monitor those "seaspaces" for infringing traffic.
Midair collisions not near an airport are vanishingly rare. The takeaway from that for me is that concentrating traffic (such as would happen when you take one degree of freedom away) would materially increase the risk.
They're also rare in absolute terms, even including the near-airport ones.
Given the size of these ‘planes’, they could possibly even act as train ferries! Imagine your standard high-speed train going into a plane to get from, say, Rome to Barcelona (or Bari to Athens or Warnemünde to Helsinki…).
Anyone know the source of the 35-50% increased fuel efficiency numbers? I'm curious if it's a point-to-point estimate, or what. It'd be pretty amazing if the efficiency was such to overcome the reduced drag from flying at higher altitudes.
I don't know the source, but I imagine they're comparing efficiency against a conventional plane flying at sea level. There's no way this can compare to flying at altitude - I mean, the fastest this thing can fly is far below stall speed at altitude - but its key advantages at sea (particularly for littoral defense against strike groups of surface ships) are that it's essentially a ship and a plane in one, doesn't need an airfield, and can hide from radar. (Given this, I'm actually surprised China hasn't been interested in this technology.)
At the tips of the wings and at the trailing edge of the wings vortices will form when a wing is surrounded by nothing but air. Closer to the ground (typically less than a wingspan of the ground) these vortices start to form but are then interrupted by the ground. This results in an increase in lift and a very strong reduction in drag. The upshot of this is that in groundeffect a powered aircraft uses much less energy to move. Several bird species (mostly the bigger water birds) know how to exploit this as well.
The aircushion of the hyperloop is more like an air hockey table. It also reduces drag but that's drag from the surface of the table rather than from the air. Think of it as a two dimensional air bearing.
Apropos wingtip vortices: that's the reason lots of large planes are now equipped with winglets, these help to stop the formation of those vortices decreasing drag and increasing lift. Some larger windmill manufacturers use them too with the same goal, but in a windmill this translates to more power produced at the same windspeed rather than less fuel consumed in a vehicle.
The ground effect is just the effect that your wings are helped by the ground. The air pushes on the water. It is not air/air but air/ground (so the incompressibility of water helps you). With this effect the plane can flight even with these small wings.
Over water a plane in groundeffect will use slightly more energy than it would over land because even though water is incompressible that is effective only when it is completely constrained. Since water open to the environment at the top can be pushed inwards some of it will do that and this will cause a rise in the water just outside of the profile of the wings of the aircraft. Over a solid surface this would not happen. Similar to how riding a bicycle with springs costs more energy than one without.
Private R&D for an ekranoplan-size aircraft might be difficult, but if it could work just as well for smaller aircraft, this might be an option to consider.
Does anyone know if the ground effect is affected by wingspan?
They are pretty dangerous. A good number of them crashed. Some in choppy seas. It is hard to train pilots for it. In one case, the sea was getting choppy and pilots did what well pilots do. They pulled up to increase the altitude. That disrupted the ground effect and the craft crashed.
However, this is something that should be addressable nowadays. One should be able to design a system where a ladar scans the water surface ahead and a computer uses that information and various control surfaces on the wings to compensate for waves below the wings. It sounds very complex but it should be doable.
Of course, the ocean can produce waves that are much too big for ekranoplans regardless of what stability technology one uses. But another modern advantage is that we can now know the state of the ocean everywhere at any time, so a solution for this is that the ekranoplans simply should avoid areas with large waves.
These vehicles would be perfect for fast transport if fuel prices were lower. The problem is that with today's high fuel prices, the demand for fast but energy inefficient transport is not enough to justify researching new aircraft types.
But this also has good military potential. It is fast and yet it can carry much more weight than an airplane. It can carry enough armor to make it immune to anti-air missiles, yet it is fast enough to escape anti-ship missiles. It can carry all the active anti-missile technology of a warship, but not be a slow sitting duck like a warship. It can carry a powerful ship borne radar, yet move together with fighter formations. It can carry attack troops to beaches at high speeds and then land in the water right in front of the beach.
So .... a lot of potential.