ClaytonLittle
New Member
Hey everyone just thought I'd share this little experiment I did on ground effect vehicles, comparing three major GEV designs. From left to right, I have the Bixel, the Lippisch, and the Ekranoplan designs. I used Hoverman's plans for the Bixel and RdsG's for the Lippisch.
Each one was made with approximately the same wing surface area and the same materials. The cg of each was also balanced with a single metal bolt. The weights of each, however, are not similar, as I considered that an element of each respective design, and therefore subject to being experienced as an advantage or disadvantage by that design.
I threw each one with unequal speed, because each design needed a specific speed to fly well, a factor I also considered to be an inherent element of each design. The following is the maximum range I was able to squeeze out of each:
Bixel: 17.7 meters
Lippisch: 16.7 meters
Ekranoplan: 20.1 meters
The Ekranoplan was by far the easiest to get flying, however if thrown too hard, it would quickly fly out of ground effect and stall. It also required the least amount of tweaking to get flying out of the three, which is curious as most sources agree that the Ekranoplan design has bad longitudinal stability comparatively. I am willing to accept that I may have just gotten lucky with my model, and it came out almost balanced initially. However, now that I think about, it was the most particular out of three when it came to launch speed, and would only fly with very specific launch force. I can imagine how it would be a pain to control it in a full size GEV when the speed is variable during flight.
The Bixel design was also quite easy to fly, but required considerably more speed than the Ekranoplan. It also had an interesting quality in that, no matter how hard I threw it, it would never exit ground effect, but simply fly a couple centimeters higher than if I had thrown it softly. I am not sure if it would exit if I could have thrown it faster. The Ekranoplan and Bixel had comparable stability, with the Bixel bouncing around a bit before becoming stable. I made the rear elevator on the Bixel adjustable, but after messing around with it for several minutes, I found that it only flew when the elevator had no positive or negative pitch at all
. I was also able to put a little handle right in the middle, where the cg was, which made it very easy to launch.
The Lippisch required a lot of speed to get flying. However, it was also the most stable, though not by much. If the nose got to high due to a rock or launch error, it would immediately flip, while the other two models would just stall then glide to a moderately soft landing. Other than that, if it didn't flip, the Lippisch flew well. The Lippisch was a pain to get balanced and flying, as it was touchy longitudinally, and required a very far forward cg, or at least I needed to shift it very far from where it was without the weight. With only one bolt available to balance with, I was forced to extend the weight out very far using dowels to get the proper balance. Not happy with that.
My favorite by far is the Bixel design, with the Ekranoplan in a close second. The bixel flies much closer to the ground with a nice, smooth flight after it becomes stable, while the Ekranoplan kind of bobbed as it flew.
More information on the Bixel design can be found here: Bixel_WIG
Thanks for reading, I hope this is helpful.
Clayton
P.S. I have just the minimum amount of knowledge needed to build these models, so I'll probably be unable to discuss ground effect and aerodynamics to the degree of expertise as these guys did: https://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/7434-wing-ground-effect-boat.html
Each one was made with approximately the same wing surface area and the same materials. The cg of each was also balanced with a single metal bolt. The weights of each, however, are not similar, as I considered that an element of each respective design, and therefore subject to being experienced as an advantage or disadvantage by that design.
I threw each one with unequal speed, because each design needed a specific speed to fly well, a factor I also considered to be an inherent element of each design. The following is the maximum range I was able to squeeze out of each:
Bixel: 17.7 meters
Lippisch: 16.7 meters
Ekranoplan: 20.1 meters
The Ekranoplan was by far the easiest to get flying, however if thrown too hard, it would quickly fly out of ground effect and stall. It also required the least amount of tweaking to get flying out of the three, which is curious as most sources agree that the Ekranoplan design has bad longitudinal stability comparatively. I am willing to accept that I may have just gotten lucky with my model, and it came out almost balanced initially. However, now that I think about, it was the most particular out of three when it came to launch speed, and would only fly with very specific launch force. I can imagine how it would be a pain to control it in a full size GEV when the speed is variable during flight.
The Bixel design was also quite easy to fly, but required considerably more speed than the Ekranoplan. It also had an interesting quality in that, no matter how hard I threw it, it would never exit ground effect, but simply fly a couple centimeters higher than if I had thrown it softly. I am not sure if it would exit if I could have thrown it faster. The Ekranoplan and Bixel had comparable stability, with the Bixel bouncing around a bit before becoming stable. I made the rear elevator on the Bixel adjustable, but after messing around with it for several minutes, I found that it only flew when the elevator had no positive or negative pitch at all
The Lippisch required a lot of speed to get flying. However, it was also the most stable, though not by much. If the nose got to high due to a rock or launch error, it would immediately flip, while the other two models would just stall then glide to a moderately soft landing. Other than that, if it didn't flip, the Lippisch flew well. The Lippisch was a pain to get balanced and flying, as it was touchy longitudinally, and required a very far forward cg, or at least I needed to shift it very far from where it was without the weight. With only one bolt available to balance with, I was forced to extend the weight out very far using dowels to get the proper balance. Not happy with that.
My favorite by far is the Bixel design, with the Ekranoplan in a close second. The bixel flies much closer to the ground with a nice, smooth flight after it becomes stable, while the Ekranoplan kind of bobbed as it flew.
More information on the Bixel design can be found here: Bixel_WIG
Thanks for reading, I hope this is helpful.
Clayton
P.S. I have just the minimum amount of knowledge needed to build these models, so I'll probably be unable to discuss ground effect and aerodynamics to the degree of expertise as these guys did: https://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/7434-wing-ground-effect-boat.html
