How the Seaglider wing is different from the ekranoplan wing

Flying in ground effect unlocks incredible aerodynamic efficiencies, but for decades, it’s been a notoriously difficult regime to operate in—prone to instability and hard to control. Earlier attempts at wing-in-ground effect vehicles, like the Soviet-era ekranoplans, tried to brute-force stability through unconventional wing designs at the expense of efficiency.

At REGENT, we’ve taken a fundamentally different approach. By pairing standard high-efficiency wing designs with modern digital flight control systems, our Seaglider vessels maintain stability in ground effect without compromising performance. It’s a breakthrough that lets us safely harness the full potential of this aerodynamic sweet spot, and it’s key to why our Seaglider craft can finally deliver on the promise that earlier WIG vehicles never could.

Read why the Seaglider craft succeeds where ekranoplans failed.

The challenge of flying in ground effect

In most airplanes, WIGs included, the tail “lifts” downwards. Think of the airplane or WIG like a see-saw with the pivot on the center of gravity (by the nose). The more the tail pushes downwards, the more the nose rises. 

Lift is generated by the wing redirecting the air downwards (the equal and opposite force to pushing the air down is the air pushing backup on the wing!). This downwards flow aft of the wing is called “downwash”.

The more an airfoil (like a wing, or a tail) turns the airflow, the more lift it creates. The angle between the line drawn from the nose to the tail of the airfoil (the “chordline”), and the incoming air, is called the angle of attack. The greater the angle of attack, the more the air foil turns the air, and the more lift it generates. This is why an airplane pitches its nose up to takeoff: it increases the angle of attack on the wings to generate enough lift to leave the ground. 

When an airplane enters ground effect, the downwash is reduced. The ground gets in the way of the downwash and keeps the airflow straighter. This is what decreases drag and makes ground effect so efficient.

But, when the flow straightens, it changes what the tail sees. Remember that the tail is generating downwards lift. 

And because the tail is an upside-down airfoil, it works in the same way as the wing, but the angle of attack and lift are flipped. 

At altitude (outside of ground effect), the tail sees the downwash from the wing.

But in ground effect, the downwash is reduced, meaning the angle of attack is smaller, meaning the tail generates less downwards lift.

Going back to our see-saw, less downwards lift at the tail is the same as pushing up on the tail – so pushing up on the tail makes the nose go down. 

Remember all this happened because we entered ground effect. So we lowered our altitude to enter ground effect, and then our nose goes down. This leads us to descend even more, which makes the ground effect stronger, which reduces the wing downwash on the tail even more, which reduces the tail downforce even more, which makes the nose go down even more — eventually, all the way into the ground. This is called ”instability” and was very challenging for early WIG captains and designers. 

3 early WIG designs

There have been three kinds of WIG design before the Seaglider one — all of which attempted to fix this instability issue with wing design. 

The ekranoplans used (A), basically trying to separate the wing and tail absolutely as far as possible so the ground effect and wing downwash would not affect the tail. This led to very heavy designs because so much structural reinforcement was required to build these giant tails so far away from the main wing. 

Other types of WIGs used the reverse-delta (B) or the tandem-wing (C). In both cases, it works the same with upwards lift being ahead of the center of gravity see-saw. 

Ground effect increases lift. So, with the (B) and (C) designs, when the nose drops down and gets closer to the ground, the lift on the front part of the wing (or the front wing) get stronger, and pushes the nose back up. This would seem to solve the stability problem, but these wing designs are not very aerodynamically efficient. It turns out that, even with the efficiency benefits of ground effect, these wing designs are no more efficient than a normal aircraft. 

So, the ekranoplan design (A) leads to a really, really heavy WIG, and designs (B) and (C) lead to inefficient ones, which defeats the whole purpose of ground effect. 

The Seaglider solution

We don’t need to fix instability with wing design anymore! Now we have advanced digital flight control systems that can control even unstable vehicles. REGENT Seaglider vessels use digital control systems to protect their flight envelope and ensure safety in all cases.