Zubr Class skirtless hovercraft

[Destroyer500]

Would it technologically be possible to make the Zubr Class hovercraft skirtless just like this guys designs ?

No matter the opinion i would like to receive some info on which mathematical formulas to use regarding the design of such a thing.I am almost an engineer myself so im familiar with formulas math,coeficients and all that jazz and i can learn a few (or a lot) more if they help my theoretical project move further ahead

When i say skirtless i dont mean open plenum i mean one that works with a peripheral jet.Open plenum is very inefficient

 

[DougM]

It is a matter of air presser (in over simplified term). you need to push down hard enough to push up however much weight your vehicle needs.
In the case if the lift platform show in the still of video that is not as that weights next to nothing.
The problem with this is when you build anything of significant weight then you need a lot up upwards pressure. But the air you are pushing down without a skirt to contain it simply ”spills” out the sides and does mot build pressure.
It is like trying to fill a balloon that has a hole in it. You need a LOT more air moving in any give time. So much air that it cant all escape,
So you basically are building a VTOL aircraft. And just keeping it in takeoff mode 100% of the time,
You would be better off building a helicopter.
And yes you get a bit of an advantage with always being in ”ground effects mod”. But i was trying to simplify.

 

[Destroyer500]

It is a matter of air presser (in over simplified term). you need to push down hard enough to push up however much weight your vehicle needs.
In the case if the lift platform show in the still of video that is not as that weights next to nothing.
The problem with this is when you build anything of significant weight then you need a lot up upwards pressure. But the air you are pushing down without a skirt to contain it simply ”spills” out the sides and does mot build pressure.
It is like trying to fill a balloon that has a hole in it. You need a LOT more air moving in any give time. So much air that it cant all escape,
So you basically are building a VTOL aircraft. And just keeping it in takeoff mode 100% of the time,
You would be better off building a helicopter.
And yes you get a bit of an advantage with always being in ”ground effects mod”. But i was trying to simplify.

So there is no other way around this ? Its VTOLish no matter what if it doesnt have a skirt ? Wouldnt ground effect help with this as soon as it was airbone and started moving ?
Is there at least an efficient way to achieve VTOL ? I was thinking of something like this https://en.wikipedia.org/wiki/Vortex_engine being used to lift it and then some kind of ground effect could help it go forward
There were things like this https://en.wikipedia.org/wiki/Lockheed_CL-1201 that were proposed to lift themselfs up and then fly in a VTOL manner and that thing is far far heavier than what im proposing

 

[Orcbuster]

Not possible, mass/sustained power ratios simply do not add up. We're talking an object with an empty mass of 3 C-5 galaxies.

 

[DougM]

NOTE THE FOLLOWING IS MAJORLY OVER SIMPLIFIED
Ground effect is an interest thing, It is why the Great Caspian Sea Monster and her flock could work ak ekronoplanes (sp?)
It is one reason that Sail planes have landing issues and one reason the U2 sucks to land. As the closer it gets the more it resist landing.
It is part of the reason big plans have those spoiler things to dump the lift.
It is in part why some race cars do odd things when you change the angle of attack. See F-1 cars proposing. As the air builds up under them lifting them up then it bleeds out and they are sucked back down and so for and so on.
And so on and so forth.
But ground effect is related to or sort of (to massively over simplify) is the air you are pushing down, not being able to get out of the way abd thus stacking up under you.
In the case of hover craft this is the whole point.
With VTOL aircraft such as the F-35 or the Harrier jump jet this can be a HUGE issue as that air escapes from under your wings and fuselage and is pulled back in and injected by your jet or lift engine, and that air is hot and has been used once already by your jet so it can cause you to stall this can and HAS led to crashes.

Now trying to build a skirtless hover craft has all those advantages and disadvantages but it will always operate in close association to the ground, but not moving very fast vs say an Ekronoplane.
Thus was actual tried at least once. Look up the Avrocar. Looks like the illegitimate offspring of a hovercraft, and F-35 (the lift fan) and a 1950s flying saucer. In that case they were hoping for a true VTOL but even with a LOT of power (for the time) it could not get above a hover. Which is what you want. So it can in theory be done
The problem that learned from it was that the air escaping is of not a lot of use. And you need a TON of thrust to lift the thing as it is operating on the same principle as a VTOL jet or the F-35 in that you trust straight down hard enough you can lift up.
This is the same way a VTOL works and an F-15 when it stands on its tail.
It is also how rockets tack off and how SpaceX lands their rockets.
Total weight of aircarft (including fuel and passenger and such) =X so you need X thrust down to hold said vehicle in a hover and X+Y to control where Y is what you lose to controlling it and inefficiency and you need X+Y+Z to lift it were Z is based on how much you want to lift.
If you are just letting the thing hover near the ground you gain a little bit from the air not being able to escape as fast as you are pushing it below your hover craft. But that is not very much. So you need a really powerful engine.

A hover craft works like a leaking tire inner tube And a big compressor. My tractors tire sprung a leak yesterday. I was flat and off the rim by the time I got it back to my garage. I have a BIG compressor. So i put it more of less back on and connected my BIG compressor and the inner tube expanded pushing the tire onto the rim. And as long as I kept the air pump connected the tire stayed inflated but it deflated fast one I took the air hose off as the Inner tube has a big leak somewhere. But if I could have driven it with the air hose attached it would have stayed inflated as long as the leak left out less air then the compress put in.

Now a hover craft works much the same way. The skirt sort of seals to the ground or water and air escapes but not THAT fast so the air forced into the space under the hover craft escapes slower then it is filled and thus it gets pressurized and lifts the hover craft like my tire lifted my tractor. But without a skirt the air will escape very very very fast and build up little pressure and thus we are back to depending on thrust.

it is a bit more complicated then that but in a nutshell that is what is going on.

 

[Destroyer500]

NOTE THE FOLLOWING IS MAJORLY OVER SIMPLIFIED
Ground effect is an interest thing, It is why the Great Caspian Sea Monster and her flock could work ak ekronoplanes (sp?)
It is one reason that Sail planes have landing issues and one reason the U2 sucks to land. As the closer it gets the more it resist landing.
It is part of the reason big plans have those spoiler things to dump the lift.
It is in part why some race cars do odd things when you change the angle of attack. See F-1 cars proposing. As the air builds up under them lifting them up then it bleeds out and they are sucked back down and so for and so on.
And so on and so forth.
But ground effect is related to or sort of (to massively over simplify) is the air you are pushing down, not being able to get out of the way abd thus stacking up under you.
In the case of hover craft this is the whole point.
With VTOL aircraft such as the F-35 or the Harrier jump jet this can be a HUGE issue as that air escapes from under your wings and fuselage and is pulled back in and injected by your jet or lift engine, and that air is hot and has been used once already by your jet so it can cause you to stall this can and HAS led to crashes.

Now trying to build a skirtless hover craft has all those advantages and disadvantages but it will always operate in close association to the ground, but not moving very fast vs say an Ekronoplane.
Thus was actual tried at least once. Look up the Avrocar. Looks like the illegitimate offspring of a hovercraft, and F-35 (the lift fan) and a 1950s flying saucer. In that case they were hoping for a true VTOL but even with a LOT of power (for the time) it could not get above a hover. Which is what you want. So it can in theory be done
The problem that learned from it was that the air escaping is of not a lot of use. And you need a TON of thrust to lift the thing as it is operating on the same principle as a VTOL jet or the F-35 in that you trust straight down hard enough you can lift up.
This is the same way a VTOL works and an F-15 when it stands on its tail.
It is also how rockets tack off and how SpaceX lands their rockets.
Total weight of aircarft (including fuel and passenger and such) =X so you need X thrust down to hold said vehicle in a hover and X+Y to control where Y is what you lose to controlling it and inefficiency and you need X+Y+Z to lift it were Z is based on how much you want to lift.
If you are just letting the thing hover near the ground you gain a little bit from the air not being able to escape as fast as you are pushing it below your hover craft. But that is not very much. So you need a really powerful engine.

A hover craft works like a leaking tire inner tube And a big compressor. My tractors tire sprung a leak yesterday. I was flat and off the rim by the time I got it back to my garage. I have a BIG compressor. So i put it more of less back on and connected my BIG compressor and the inner tube expanded pushing the tire onto the rim. And as long as I kept the air pump connected the tire stayed inflated but it deflated fast one I took the air hose off as the Inner tube has a big leak somewhere. But if I could have driven it with the air hose attached it would have stayed inflated as long as the leak left out less air then the compress put in.

Now a hover craft works much the same way. The skirt sort of seals to the ground or water and air escapes but not THAT fast so the air forced into the space under the hover craft escapes slower then it is filled and thus it gets pressurized and lifts the hover craft like my tire lifted my tractor. But without a skirt the air will escape very very very fast and build up little pressure and thus we are back to depending on thrust.

it is a bit more complicated then that but in a nutshell that is what is going on.

Ok then i understand its too much of a hustle but i have three more questions
1)What about the Vortex engine thing i mentioned with a wiki link on my previous response.Would something of that kind provide adequate thrust efficiently ?
2)What about semi solid rigid skirts made of metal/steel or something ? Skirts that basically are solid but that can move up and down to adapt to the changes in the ground.They could be like telescoping doors.To reduce friction the bottom part of those telescoping solid metal skirts could be of something flexible or at the very least smooth enough.
3)What about skirts that are made of metal but resemble "scaled armor" or scales in general again with some kind of modification to the bottom to reduce friction
My main goal is to have a hover vehicle that can move very deep inside land/move in general in land as well as water but with a flexible rubber,or whichever material of that kind,skirt youre going to be stopping every 50kms to patch it up.Plus since im talking about a miiitary vehicle that is going to be used the way i mention a few HE shells from tanks or some kind of man launched rocket aimed at the right spot is going to rip and tear the skirt.And i wont even mention mines and underground hidden explosives

 

[DougM]

They tried to use the air to form a skirt to contain the air, but it can’t hold pressure all it can do is slow the escaping air a bit. In effect it can help improve the “ground effect”. But it can’t hold pressure and thus you still need to move a ton of air to keep you hovering, the y tried this on various experiment iirc. I think it was one of the Avro Car experiments perhaps?

The idea for something like steel is interesting but steal does not flex well and is heavy. If you want yo read about something like that go find the Book Hammers Slammers it is a sci fi book written by a Vietnam vet and is about a military mercenary group that uses mostly hover craft.

Having played a bit with Metal armor, chain mail and scale mail and such and that is not going to help a lot. Even when metal armor is maid from aluminum it weighs a lot still. And scale mail is sort of metal plates attached to a backer and overlapping. So they will get ripped off.

As far as I know while the ware and tair on the skirts is an issue and a costly one at that. I think if you look into thinks a lot of the issues with using them inland is that
A) the ground is not smooth and thus the skirt will not seal to the ground as well and will leak air. Depending on how much leaks out it may cost more fuel to run the fan at a higher rate or it may ground the hovercraft, neither are good,
B) hovercrafts maneuver like a fully loaded semi on sheet ice that has been oiled and the semi truck has slick tires. In short the such at turning or stopping and that is a BAD combination.
C) Hovercraft are horribly loud this is bad for many reasons not the least is that it lets the enemy hear you from a long way off and it make communication for your men hard.
D) hovercraft are not energy efficient as they burn fuel not just to move but to lift. A truck uses tires so it only needs fuel to move,
E) the hovercraft is more like an aircraft flying low then a tank and weight is it’s single biggest concern, So trying to armor it is not easy and is all but impossible. And the skirt is especially vulnerable as if every hole no matter how small lets more air escape and that is air you must replace. A big enough hole or enough little wholes and you lose pressurization and you then lose lift. And you are stuck.

So while they have some uses and they are cool, the truth is that are just not practical.

BTW, My brother’s boyhood best friend and our neighbor joined the military and drove LCACs.