Ekranoplans are a curious class of vehicle; most well known for several Soviet craft designed to operate at sea, flying just above the waves in ground effect. [rctestflight] had accidentally come across the ground effect flight regime himself years ago, and decided it was time to build an ekranoplan of his own.
While ground-effect flight can be quite stable for a heavy, human-scale craft, the smaller RC version suffered more from minor perturbations from the wind and such. Thus, a Pixracer autopilot was installed, and combined with a small LIDAR device to accurately measure altitude above the ground. With some custom tweaks to the Ardupilot firmware, the craft was able to cleanly fly along barely a foot off the ground.
The final effect is almost mesmerizing; it appears as if the craft is hovering via some heretofore unknown technology rather than just flying in the usual sense. It’s still sensitive to breezes and sudden drops in the terrain lead to a temporary escape from the ground effect region, but the effect is nonetheless impressive. It’s a nerve wracking video at times, though, with quite a few near misses with traffic and children. Regardless of the nature of your experimental craft, be cognisant of your surroundings. We’ve seen [rctestflight]’s Ardupilot experiments before, too. Video after the break.
It’s a moot point whether this is actually demonstrating the ground effect, or whether it’s simply flying low to the ground, since these tiny RC planes have so much power to their weight that you can strap a motor to any old piece of balsawood and fly it – as exemplified by the tiny camera drone that they use.
Actual ground-effect airplanes don’t fly higher than about half the wingspan, and generally only few meters above. For example the Caspian Sea Monster had 44 meter wing span and was designed to fly 3-20 meters off the water. In scale, that would be something around 5 inches off the ground.
this guy explains it well
https://www.youtube.com/watch?v=i9sHtVzdW8Q
Yep. That’s the real deal. Now strap a 500 Watt motor and prop to it, and it just takes off – aerodynamics doesn’t matter anymore because it becomes like one of those trick planes that has enough power to stop and hover with the nose up.
That’s what I saw too. And that plane is way too light to have a sensible increase on pressure below it to call “ground effect.”
But the idea is good, and it’s nice to see how Ardupilot is well made. It could fly the first version, unstable as it was, in windy conditions, and it looked like it had everything under control.
Why is the point moot just because it can fly without ground effect? (Human scale) Ground effect flight is mostly about making something as fast as but more efficient than a regular aircraft, if this craft can also realise that goal it seems like a win. From the video they’re definitely trying to maintain it at some small fraction of the wingspan.
The project song starting at 9:07 is a really nice touch as well.
Just another snarky post from someone who doesn’t like cool things that fly.
Yeah, just because it can fly with the ground effect isn’t so special….let’s see if it can fly without the ground! Try that! :-)
As near as I can tell you must think the term “ground effect” must always be a lie. If you would try flying something you would feel ground effect for yourself. I have most experience with RC helicopters, ground effect is quite large for them, certainly nothing close to a lie.
Because you can’t tell whether any ground effect actually applies, or whether it’s just powering it through. No observable difference in behavior.
Now all that is needed is to make carry heavy cargo or start reducing the input power…push the limits then you will be able to tell the difference
Wouldn’t you know you’re succeeding if the plane is flying more efficiently than it normally would, i.e., less throttle for a given airspeed than normally possible?
Flying in ground effect is not an accomplishment. If you are flying well under half your wingspan above the ground, you really can’t help but be in ground effect. There is nothing to prove. The actual accomplishment is in the extra payload you get for a given power. If you have something to prove, and again, there IS nothing to prove, then you can use a smaller battery and/or smaller motor. If you load it up good and proper, oh, it WILL stay in ground effect, LIDAR or no.
Fun semi-related fact: In the past, “moot point” meant a point worth discussing. Only somewhat recently has the meaning evolved into its exact opposite.
Oh cool. It makes a lot more sense that way around. I would like to moot this moot point at our moot. Moot.
Woot!
That’s what I mean with it.
> It’s a moot point whether this is actually demonstrating the ground effect, or whether it’s simply flying low to the ground
Hint: It’s not.
That’s why he’s using LIDAR to create the ground-effect effect.
I’m a bit confused by what you said, the lidar does not create any effect it just measures the distance to the ground. Ground effect is created by flying a plane close to the ground and is used to make the plane more efficient.
It could be helpful to sense not only the distance to ground, but also a pressure under the wing. Unlike conventional planes, which have lower pressure above the wing, ground-effect aircraft should have higher pressure under the wing. So, if it could be stabilized, it will greatly improve stability and possibly will make aircraft resistant to breezes.
Ummm, higher pressure under the wing implies lower pressure above it
I mean absolute pressure, or, at least differential to ambient pressure (could be problematic for moving vehicle), not differential between under and above. Last one will not give you any info about the mode of flight – are we still on ground-effect, or already flying conventionally.
Lower pressure above the wing, by definition, means there’s higher pressure under the wing.
Just leaving this note to reassure Stanson that at least one person here comprehends what you are saying.
Though honestly I suspect 90%+ of HAD readers get it
And again, what is it you want to prove with this? There is no magic set of conditions that puts an airfoil in ground effect. There is a gradient above the airfoil that is lower than the surrounding air above it, and higher than the surrounding air below it. Just what is it you think needs to be proved?
There are people who insist that the first flight of the Wright flyer wasn’t true flight, because it never got above ground effect. But nobody ever needed to prove that any aircraft was capable of remaining IN ground effect. It’s like watching a car travel at 100 km/hr, and then saying, “ah, but can you prove that it can travel at 20 km/hr???”
A wing with any angle of attack will have some higher pressure than ambient on the bottom surface if only because of dynamic pressure (to put another way, the pressure generated from the wing hitting the air with the bottom surface will result in some pressure force)
But ground-effect pressure is higher, than dynamic one, that’s the whole point of ekranoplans. So, measuring pressure under the wing along with the LIDAR distance info you will get a lot of info useful for ekranoplan flight stabilisation – are we just fly or on ground effect, what is the exact value of it, is it a wind or we too low etc.
I know what you mean, but I think you’re looking for the wrong thing. If the vehicle is ‘flying’ it has enough pressure below the wing to suspend it by definition, so what you really need is a reliable measure of air speed, and some reliable tests of flight at varying altitudes. If it’s really exploiting ground effect there should be a lower speed needed to maintain level flight near the ground.
They are all conneted – air speed, height, pressure. However, pressure is the primary cause for others. First pressure grow, and than altitude changes. Inertia, you know. If you sense an altitude or air speed, and try to stabilize them, you fight with consequences. If you track pressure, you could act before altitube or airspeed change. I think this could give an advantage and make the things easier.
“the whole point of ekranoplans”
The whole point of Ekranoplans was finding a good compromise between the economy of a ship and the speed of an aircraft. At no point EVER, did someone say, “WOOT! We accomplished flight within ground effect!!!”
foamboard hot glue, suffer by sebastian,
proximity proximityieee
we are just a wing zu vorticies,
motors in the front,
elavators in the back,
manual adjustment of my angle of attack,
shooting lidar,
try not to hit a car,
as we are sitting on this concrete ocean, sailinggggg.
nice.
+1… finally some refreshing and interesting background music.
this jerk flies in the middle of an active highway, hits a kid, and at one point flies behind a car and almost into another car. great, you made an erkranoplan, and now you use it to be an a-hole. remind me how we ended up with Remote ID?
He flies down active roads in many videos it’s just asking for trouble and it does seem wreckless at times and breaking many self imposed rules of the ama to make sure that crazy laws are not imposed by local or federal gov. He does have some very good content and I hope that he stays safe.