BRILLIANT!! You sure know your stuff!! I’m a little ‘obsessed’ with hovercrafts (I have 2 personal), and have seen hundreds of videos. Nothing as clever as this! Hats-off to you sir! Cheers, Mark (Canada)
In fact the first prototype of a hovercraft was without skirts, the issue with the skirts is that the internal pressure difference generates lifting pressure exponentially increasing the psi or kPa.
interesting design and great explanation video, it seems efficient also. maybe the inner prop cylinder could have more cone shape, so that it might allow more laminar flow
Appreciate the feedback. I have used a conical diffuser duct on a previous build, it gave a very smooth operation on water and practically eliminated any turbulence underneath. But it also reduced the hover height enough that I went back to just a cylinder.
I've been watching it for a long time and I've made similar ones to the first attempts. You are doing well. I hope you will do better using an FC in the future.
I'd really need to see a picture for a proper look at what may be the issue. At 8:33 in this video I mention the torque problem. Main counter is LOTS of straightening vanes at the rear flaps and smaller swirling vanes in the stability duct. Air leaking from one flap will also cause a spin.
Interesting detail - Considering only motors used for lift - how would you compare the behaviour and performance of the 1,2 or 4 rotor skirtless craft?
How much time do you have for an answer! I'd rank number of motors below the size/weight in terms of performance. You could have a very light and high powered craft hover high on a single motor, likewise a sufficiently heavy 4 motor one won't rise all that high but would tolerate wind better. Forward thrust depends on both hull shape and general motor power. I have a small octagonal one where only one edge is available for the propulsion flap - speed is quite low, which may give the impression a single lift motor is bad. But the rectangular craft here makes far better speed both from more power and that more air is available at the propulsion flaps. Single motor naturally suits octagonal/ circular better. It struggles with a longer rectangular hull so 2 lift motors spread the airflow out more evenly. You can actually do a square hull with 2 props which is kinda strange but works alright. 4 motor one is still kicking around although hasn't been powered up for a while. Probably going to build a smaller proof of concept for the hybrid multirotor idea - haven't forgot about it. My brief impression was great hover stability until the absolute extreme heights, the 4 stability ports seem to stop the sideways "topple" off the air cushion on the 2 motor designs. Makes sense when you consider how stable quadrotors alone are, the ground acts as a stabiliser itself for the air cushion. Twin counter rotating props do counter the torque issue, although good design on a single motor one can largely eliminate it.
@@Glydaire "How much time for an answer?" - The topic so interesting I would prefer a long answer, but I am happy with the short answer 😊. I guess that the dominant factor is supplying enough air, for a given perimeter, with some left over for thrust and directional control. With a good supply, then the changing width of the peripheral jet, has a comparatively less of an effect. (I think I need to rewatch/review some of your earlier videos, and RCGroups posts)
I do have two other questions... (please) How did you arrive at having the peripheral jet angle set at 45°? (i.e. did you previously try other values) Have you made a craft that has no "centre jet from the propeller? (i.e. where all of the air feeds into the peripheral jets) [Later edit: The idea of a stability jet is first used during the evolution of the Bixel project?]
It's a nice thought but it's not happening. This design has been done at full scale, see @peterkeogh9613 on here for the originator of it. It's difficult to scale up to man-carrying while maintaining a useful air gap, there's a reason peripheral jet designs died off the instant skirts were figured out. With modern electric power and lighter constructions it is somewhat practical for a smaller craft. Another generation or two of battery development and skirtless may have a comeback. Hybrid hovercraft / ground effect again has already been done, see the "hoverwing" for a successful design. If I had the money for a big workshop and a build team, I would really like to take this full scale, as it is I'm struggling for time to even build models.
what if you undermounted the wings to make it one large planing surface? yo could even use the top wing mounts for metal bar linkages if it needs extra structural strength.
@@alexna6129 that was also a thought I had, but could add vertical stabilizers on top to bring centre of drag up higher, if lowering the wings brings the drag too far down.
Immediate problem would be them catching on the ground with any small amount of hull roll. I have this issue even with the high mounted wings and it's the main reason for avoiding rigid endplates. It would also affect the air jet toward the back, you don't want a flat surface outside of the perimeter of the base plate. I may try anhedral (downward angled) wings with flexible tips.
A 'pure' ekranoplan needs forward movement to generate the air cushion. Hovercraft also sit on an air cushion but it's static in that the air obviously moves by the lift fan but it doesn't need forward motion. You could argue any hovercraft is a ground effect vehicle but the general distinction is whether the power goes to making air cushion directly or by propelling the craft forward. Lots of GEV use power assisted ram air to help get moving. That pushes them slightly into hovercraft territory, likewise any moderately fast skirtless craft will pick up ground effect air.
BRILLIANT!! You sure know your stuff!! I’m a little ‘obsessed’ with hovercrafts (I have 2 personal), and have seen hundreds of videos. Nothing as clever as this! Hats-off to you sir!
Cheers,
Mark (Canada)
Absolutely brilliant ! only the mixings part hurt my brain ...... Very fasinated ❤😉🙃😎 NZ
Чудове відео. Дуже добре все розтлумачив.
In fact the first prototype of a hovercraft was without skirts, the issue with the skirts is that the internal pressure difference generates lifting pressure exponentially increasing the psi or kPa.
Fantastic, Well done, just carry on mate you will make it, ( very good effort )
Getting a big Star Wars vibe!
very interesting indeed, nice video.
If that's scalable then you have something there alright . Nice .
Basically just about any project is scalable. You use inch measurements to design and feet to scale up.
@@robertblackshear8963 Not necessarily. Not everything works through scaling .
interesting design and great explanation video, it seems efficient also. maybe the inner prop cylinder could have more cone shape, so that it might allow more laminar flow
Appreciate the feedback. I have used a conical diffuser duct on a previous build, it gave a very smooth operation on water and practically eliminated any turbulence underneath. But it also reduced the hover height enough that I went back to just a cylinder.
That's more like an Ekranoplan-hovercraft hybrid. Interesting idea.
I've been watching it for a long time and I've made similar ones to the first attempts. You are doing well. I hope you will do better using an FC in the future.
awesome!
cool idea. i think front "ramp" should be flipped to catch more ground air.
He explained why he's not doing that in the video. But to summarize, it completely screws up the pitch stability.
@@VestedUTuber oh , well dang
HOW DO YOU AVOID COUNTER ROTATION WHERE THE WHOLE VEHICLE SPINS EVERY TIME IVE TRIED TO REMAKE IT IT JUST SPINS
I'd really need to see a picture for a proper look at what may be the issue. At 8:33 in this video I mention the torque problem. Main counter is LOTS of straightening vanes at the rear flaps and smaller swirling vanes in the stability duct. Air leaking from one flap will also cause a spin.
Interesting detail - Considering only motors used for lift - how would you compare the behaviour and performance of the 1,2 or 4 rotor skirtless craft?
How much time do you have for an answer!
I'd rank number of motors below the size/weight in terms of performance. You could have a very light and high powered craft hover high on a single motor, likewise a sufficiently heavy 4 motor one won't rise all that high but would tolerate wind better.
Forward thrust depends on both hull shape and general motor power. I have a small octagonal one where only one edge is available for the propulsion flap - speed is quite low, which may give the impression a single lift motor is bad. But the rectangular craft here makes far better speed both from more power and that more air is available at the propulsion flaps.
Single motor naturally suits octagonal/ circular better. It struggles with a longer rectangular hull so 2 lift motors spread the airflow out more evenly. You can actually do a square hull with 2 props which is kinda strange but works alright.
4 motor one is still kicking around although hasn't been powered up for a while. Probably going to build a smaller proof of concept for the hybrid multirotor idea - haven't forgot about it. My brief impression was great hover stability until the absolute extreme heights, the 4 stability ports seem to stop the sideways "topple" off the air cushion on the 2 motor designs. Makes sense when you consider how stable quadrotors alone are, the ground acts as a stabiliser itself for the air cushion.
Twin counter rotating props do counter the torque issue, although good design on a single motor one can largely eliminate it.
@@Glydaire "How much time for an answer?" - The topic so interesting I would prefer a long answer, but I am happy with the short answer 😊.
I guess that the dominant factor is supplying enough air, for a given perimeter, with some left over for thrust and directional control. With a good supply, then the changing width of the peripheral jet, has a comparatively less of an effect. (I think I need to rewatch/review some of your earlier videos, and RCGroups posts)
I do have two other questions... (please)
How did you arrive at having the peripheral jet angle set at 45°? (i.e. did you previously try other values)
Have you made a craft that has no "centre jet from the propeller? (i.e. where all of the air feeds into the peripheral jets) [Later edit: The idea of a stability jet is first used during the evolution of the Bixel project?]
(... I have been reading back through RCGroups posts and found when stability ports and then later stability circles were introduced. 😊 )
Saw this. Build a passenger sized craft. RC toys are fine, but you succeeded when you can pilot your build.
It's a nice thought but it's not happening.
This design has been done at full scale, see @peterkeogh9613 on here for the originator of it. It's difficult to scale up to man-carrying while maintaining a useful air gap, there's a reason peripheral jet designs died off the instant skirts were figured out. With modern electric power and lighter constructions it is somewhat practical for a smaller craft. Another generation or two of battery development and skirtless may have a comeback.
Hybrid hovercraft / ground effect again has already been done, see the "hoverwing" for a successful design.
If I had the money for a big workshop and a build team, I would really like to take this full scale, as it is I'm struggling for time to even build models.
what if you undermounted the wings to make it one large planing surface? yo could even use the top wing mounts for metal bar linkages if it needs extra structural strength.
Flip issue mb?
@@alexna6129 that was also a thought I had, but could add vertical stabilizers on top to bring centre of drag up higher, if lowering the wings brings the drag too far down.
Immediate problem would be them catching on the ground with any small amount of hull roll. I have this issue even with the high mounted wings and it's the main reason for avoiding rigid endplates.
It would also affect the air jet toward the back, you don't want a flat surface outside of the perimeter of the base plate.
I may try anhedral (downward angled) wings with flexible tips.
I hope at some point you or someone else scales this up to something that can be piloted. Interesting stuff to say the least.
ua-cam.com/users/shortsKT7rk4-xN-I
Isn't this more of an ekranoplan than a hovercraft? I mean, you are using the ground effect to stay aloft
A 'pure' ekranoplan needs forward movement to generate the air cushion. Hovercraft also sit on an air cushion but it's static in that the air obviously moves by the lift fan but it doesn't need forward motion.
You could argue any hovercraft is a ground effect vehicle but the general distinction is whether the power goes to making air cushion directly or by propelling the craft forward.
Lots of GEV use power assisted ram air to help get moving. That pushes them slightly into hovercraft territory, likewise any moderately fast skirtless craft will pick up ground effect air.
Lol, your drone must be low on power