SkyLifter is an eVTOL air crane (opens in new tab)

> 250 tonnes is A LOT to lift. Look how big a hot air balloon needs to be to lift a few passengers in a basket. Sure helium has more lifting power but it doesn't create miracles. That means the balloon would have to be absolutely massive.

Agreed, per my calculations it'll need to be around 120m wide, and 30 deep (lifeisstillgood comes up with slightly smaller numbers of 100 x 25, possibly because they used 1.1kg / m3 where I used 1 for the lifting power of helium). That's more or less a baseball field.

And it's just for the naked payload, you still need to account for the envelope itself, the solar panels, the cabin, the engines, the batteries, and the fuel (as, per site, it has a biofuel backup). That probably adds a dozen tonnes at least (the solar panels alone would be 5-10 depending how much of the top's surface is covered). By the end you're probably looking at a men's cricket field, one on the large size.

Indeed, the Hindenburg could lift over 200tons however it’s useful lift (lifting capacity minus its own weight and structural limitations) was only about 10 tons…

Even if we ignore the lifting gas requirements just the structural requirements to be able to tie 250tons to the lifting body make this pretty much impossible.

This makes solar roadways and the air condenser solar water bottles seem viable.

For comparison the Airlander and P-791 only lift about 10-20 tons…

https://en.m.wikipedia.org/wiki/Lockheed_Martin_P-791

https://en.m.wikipedia.org/wiki/Hybrid_Air_Vehicles_Airlande...

Yes. Also, I was unable to find any information about the gas itself. The word "helium" isn't found on the website, they only mention "LTA"... Using helium could probably not be called green or sustainable, as it's not a renewable resource on earth, AFAIK.

I thought the website was more engineery than slick, but more specifically, the up to 250 tonnes appears to mean, we can envision building one of a sufficient size to deal with that. They have mockups of a 2, 25 and 250 tonnes, and the scale of the big one does seem very large:

https://www.skylifter.eu/air-crane/

So is this reaction just getting caught up on combining images of the small model, with the load capacity of the (theoretical) biggest model? There's lots of things, like cranes, that have a fairly standard size and a few mega sized examples used for very specific tasks.

My thoughts could not have been captured better than this.

This whole thing, like that flying wind-turbine thing or the solar road thing, is just bordering on plausible but so far away from feasible that one has to doubt the whole effort.

Its hard to imagine, in todays world of information at our fingertips that anyone could fool or misguide someone else, but as the current state of the world is, not only is a con job possible, but its getting easier and more profitable. The trick seems to be to be to make an idea, as I said above, bordering on the plausible but far away from feasible.

Yeah 250 tonnes is a lot.

Not sure if there is an alternative to helium or hydrogen, like maybe a void container, but it would still be heavy.

I guess they will suffer from bad press if they can't prove this can work. Easy to lie to investors but unless they have a prototype, I'm still very skeptical.

> 250 tonnes is A LOT to lift. Look how big a hot air balloon needs to be to lift a few passengers in a basket.

Does it scale? Can you strap 10 of those things together (perhaps using some sort of scaffolding) to lift 10x the weight?

I wonder if it would work in Venus atmosphere?

I came to admit I can't imagine how the small solar power "field" shown on top of the balloon could possible push that shape through the air - either at a reasonable speed for transport or to counteract wind. If lift isn't a problem as you pointed out above, what might work is a tethered version that basically replaced the need for a tower crane. You could develop a tethered, active mooring that was much like the four-point active anchor system the navy uses to accurately maintain position during submarine rescue.

>> that is 100mx100mx25m

That’s huge!

I wondered how big was the hindenberg, wiki claims 245m long and 41m wide, and 41m tall (excl. cabin). Only 200k litres of gas capacity. 232k tonnes lift.

Tons of companies over the years have taken a shot at it (CargoLifter, Aeros, Walrus HULA, HAV).

Turns out, so far, it's all been pretty shit, because outside of super specific niches airships are so slow they need to be much cheaper than aircraft, but the upfront costs to create massive-enough airships to even have a chance makes it a difficult proposition.

CargoLifter for me personally marks the beginning of the German Decline in Engineering. The reasons for why it failed are the same reasons why we have such large problems with infrastructure projects and are falling behind in innovative technology.

It's a very sad read.

Because it doesn’t work. You’d need a foot ball field of area, and a 3 story building, to life a small yacht like space.

The wind forces on the surface would be extreme, and you’d need a lot of power to even stay somewhere stationary instead of flying away. All of this would add weight, increasing the volume of helium needed, increasing the wind exposed surface area, making the problem worse.

You’d need a huge industrial hall to store it safely on the ground, and you can’t tie it with a rope anywhere.

The helium required to fill the balloon would make the operating costs of this thing absurd, cause it’s a lot of helium, that leaks all the time and have to be replenished, and helium is super expensive (and necessary for pricy things like cooling superconducting magnets applications, which have infinite budget).

Any 3rd year University student with basic knowledge of fluid mechanics, thermodynamics, and mechanic, can draft in a napkin why we already know that this can’t work.

I’ve sat in meetings where the VCs contracted me and others to do DD on these types of companies, where every contractor told them that this can’t physically work, and the VCs with too much money take that knowledge and translate it to “very high risk investment”. These companies got 100 million dollars and burnt through them, without nothing to show, but for the VC was more important to not have that money parked somewhere and be able to tell investors that they have “mobility companies” in their portfolio, which I think is borderline misleading / scamming because everyone knew that these companies “concepts” couldn’t physically move a thing, cause that was a physical impossibility with the tech that they wanted to use.

I think comparing it to a plane is misplaced. They call it a crane. Presumably the load and the craft arrives on a truck and you use it to hoist the load up the last few maybe hundreds of meter max. Do i read that wrong?

Edit: yes! I was reading that wrong. To quote the relevant part: “SkyLifters fly from job to job, so they can do work in locations that would be challenging for land cranes.”

Just fly it close to the ground and the only controlled airspace is near airports (and some big cities, military stuff, etc). Should not be that hard to stay out of those for the most part if you are transporting stuff like windmill parts to the middle of nowhere.

Basically two methods:

1) have counterweights (e.g. as mentioned above for another similar concept Cargolifter which used water);

2) expand its volume during loading and contract after unloading. E.g. pumps compress gas while unloading and release it back while loading.

These two options are obviously the same thing - change the vehicle density to adjust the buoyancy but implemented with and without external weights. Submarines do this also by filling the ballasts tanks with either water or flushing them with compressed air.

I looks like they tether it to the ground with tension cables to weights or piles when they are lifting very heavy loads. If this was replacing a standard construction crane that would be economic as these things often have their own significant foundations. If it's a piled foundation for a building it's not uncommon to put extra piles in where you will have cranes. Maybe smaller loads can be done with bladders as others have suggested. You only have to lift 25 tonnes to beat the MI-26 which is the biggest heavy lift chopper and hard to get hold of.

I was wondering about the same thing. It doesn't seem to be explained on the company site.

The only thing I could come up with is to have neutral buoyancy air blatters that can expand/contract. These would be inside the volume of buoyant gas but connected to the outside air. Then pump the buoyant gas into a pressure tank to reduce buoyancy, or release it from the tank to increase buoyancy.

It can just swap weight(s).