9
$\begingroup$

Ekranoplans or Ground Effect Vehicles (GEV) fly low enough to the ground that their wings stay in the ground effect. This increases lift and efficiency.

But GEV fly in the lower atmosphere (literally ground level) which greatly increases drag compared to flying in the stratosphere.

Is it possible that a GEV designed using contemporary composite materials and high bypass engines could be more efficient per cargo weight-mile (or passenger mile) than a tradition airliner? Or are GEV inherently less efficient due to the altitude they fly at?

This question is specific to fuel efficiency over distance. Feasibility, safety, navigation, time, and cost of airframe are not part of the equation.

$\endgroup$
  • $\begingroup$ This nasa study suggests GEV could be more efficient but it’s light on details: nari.arc.nasa.gov/sites/default/files/attachments/… $\endgroup$ – RoboKaren Nov 20 '19 at 15:41
  • $\begingroup$ .. but it’s the reason I ask the question because at least my received wisdom is that GEV were inherently inefficient except for very short hops such as crossing the Caspian Sea. $\endgroup$ – RoboKaren Nov 20 '19 at 15:42
  • 1
    $\begingroup$ I always thought that the extremely low aspect ratio negated most of the ground effect benefit from an efficiency perspective. $\endgroup$ – John K Nov 20 '19 at 17:20
  • 3
    $\begingroup$ @JohnK, no. Much of the ground effect per se manifests itself in reduction of induced drag - which is exactly the reason to have long wingspan on 'normal' airplanes. GEV simply don't need long wingspan: they achieve low induced drag by other means. Furthermore, ground effects generally scale with wing chord, so GEV benefit from wider chord. $\endgroup$ – Zeus Nov 21 '19 at 1:02
  • $\begingroup$ You need to specify the trip length, as it takes time to climb to altitude. A GEV would be more efficient for trips where there isn't time to reach altitude. $\endgroup$ – Robin Bennett Nov 21 '19 at 9:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.