Heaviest Lifting Aircraft?

[sanman]

I was reading about some recent announcements by Aeros and their competitor SkyCat, both of whom are seeking to marke large hybrid airships as a means of transporting very heavy payloads through the air.

I'd like to ask, what would be the best engineering solution to safely transport the heaviest payloads through the air?

I think we've all heard of the heavy-lifting conventional aircraft, like An225 and Airbus380. But if I recall correctly, their payloads max out at a couple of hundred tonnes.

If one wanted to go to the thousand-tonne level, what engineering solution would be the most practical way to achieve this?

http://www.aerosml.com/aeroscraft_ML866.asp

http://www.worldskycat.com/skycat/features.html

http://www.dynalifter.com/Dynaliftercom/RoadlessTrucking.htm

 

[FredGarvin]

That's a tough problem to crack. That kind of weight would never be transportable on a conventional sized aircraft. It would have to be extremely large. A huge dirigible is really the only way it could be possible. Loads like that right now are only transportable by ship.

 

[sanman]

Buoyancy-based solutions mean maximizing the volume/displacement to maximize the lift through that method. Aerodynamic wing-based solutions mean maximizing the amount of airflow contact with the wing, either through increased surface or increased airflow rate.

I was just mulling over what might be the best design compromise.

Maximizing lift by volumetric displacement tends to favor a spherical shape, since that's easiest structure to maintain as the size goes up. Maximizing lift by wing surface seems to favor the U2-style long lateral-span wings. Maximizing lift by airspeed would tend to favor the Concorde-style longitudinally elongated wings.

Some professor mentioned the idea of a large donut/innertube shaped airship that would have a central fan/rotor in its donut-hole. This would maximize ground effect cushioning, like a hovercraft.

Then there's that famous book, the Deltoid Pumpkinseed, which is about an aircraft having that shape.

I'd also imagine that any waste heat from the engines could be usefully applied to heating the lifting gas, for increased buoyancy. This would increase the efficiency of the aircraft. I'm not sure what geometry would be optimal for this.

What else?

 

[sanman]

Oh yeah, variable wing geometry.

Millenium airship has the idea of rotating wing-thrusters:

http://www.millenniumairship.com/ITAMMS.htm

 

[russ_watters]

How 'bout ground effect craft? (Only good over water, though...) http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml

Boeing has recently taken interest in the WIG phenomenon and proposed a concept for a massive craft to meet a US Army need for a long-range heavy transport. Called the Pelican, the 500 ft (153 m) span vehicle would carry up to 2,800,000 lb (1,270,060 kg) of cargo while cruising as low as 20 ft (6 m) over water or up to 20,000 ft (6,100 m) over land. Unlike the Soviet concepts, the Pelican would not operate from water, but from conventional runways using a series of 76 wheels as landing gear.

 

[sanman]

That's a tough problem to crack. That kind of weight would never be transportable on a conventional sized aircraft. It would have to be extremely large. A huge dirigible is really the only way it could be possible. Loads like that right now are only transportable by ship.

But it's not as tough to crack as ice. Even the biggest ships can't plough through the polar icecap during the colder months.
(Hullo, any DARPA-grant scouts lurking on this board? Hullo? Hullo?)

 

[sanman]

How 'bout ground effect craft? (Only good over water, though...) http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml

I dunno, those Ekranoplans had too many crashes, and so I'm not sure I'd trust the Pelican, even if it does look more like a regular aircraft. Besides, arctic surface with ice floes and icebergs would make it trickier.

Say... Russ... Waters... that's not an alias, is it?

 

[sanman]

Here's more on the planned Aeroscraft:

http://www.flightglobal.com/articles/2007/08/14/215960/worldwide-aeros-to-build-partially-buoyant-civil-airship.html

Notice that they mention some kind of dynamic buoyancy adjustement system, called COSH ("control of structural heaviness")
They're claiming that this will help to manage issues of buoyancy, such as arise when offloading payload, etc.

 

[kach22i]

Some great links posted, most of them are new to me and I've seen a lot on the Internet before.

Hybrid airships of lifting body/flying wing and or donut shaped Coanda effect seem to be the best choices.

Heavy typicaly means by naval ship or large bardge for a reason.

If going over ice, water or very flat land a large hovercraft or hover-bardge must also be considered.

 

[mgb_phys]

If going over ice, water or very flat land a large hovercraft or hover-bardge must also be considered.

I think it's a question of cost/time.
The cross channel (UK-France) hovercrafts were retired 10years ago - they basically use almost the same fuel as a plane but are no faster than a hydrofoil.
You need to find a market where being able to move 3-5x airfreight loads at half airfreight speeds but at roughly airfreight costs makes sense.
Except for very special markets were time matters more than money - like military, or where the terrain is impossible for ships - like the artic.
There was a company proposing to build small (100 container) hydrofoil freight ships that could do transatlantic in <4 days but I don't think they found any backers.

 

[DaveC426913]

Mega-scale ballistic railguns and very big pillows?

 

[kach22i]

use almost the same fuel as a plane

Dang thirsty turbines do that in anything you put them in.

Huge payload difference, hovercraft is king there.

 

[sanman]

Ion-Wind Propulsion?

When an airship has such huge surface area, I wonder if this couldn't be exploited for propulsion purposes as well. What about the idea of ion-wind propulsion using the skin of the airship?

http://arstechnica.com/news.ars/post/20070816-ion-wind-cooling-could-revolutionize-cpu-cooling.html

If ion-wind can accelerate the boundary-layer, perhaps this can translate into propulsion gains. Since ion wind devices are showing 250% performance gains over conventional fans for cool purposes, then perhaps likewise they would show some performance gains for propulsion applications.

For CPU cooling, researchers are trying to shrink the millimeter-sized components down to micrometer size, but for airship propulsion it would be useful to go the other way -- enlarging the effect from millimeters to meters.

Consider that for a high-altitude airship operating at 100,000 ft, there would already be a much higher fraction of ionized gas molecules up there anyway. The thinner atmospheric density and consequent lower air resistance could allow an airship to accelerate to much higher speeds. Meanwhile, the greater intensity of solar radiation could also be harvested by the airship's large surface area, which could also be used to store the electric charge. If lightweight structural materials like aerogel were used, then these materials with their high internal surface area could also be used for charge capacitance purposes.

 

[kach22i]

If ion-wind

FYI: about 100 years ago the US government got involved in providing funds for loudspeaker develpoment.

The contestants were:

1. Dynamic loudspeaker (cone and magnet)

2. Electrostatic speaker (stretched pig skin, long before Mylar was invented).

3. The ion speaker.

The Dynamic Loudspeaker we all know won. The electrostatic caught fire and was eliminated. The Ion speaker had the potential to kill the listener if left in an enclosed space, not a good selling point.

Becarefull with that ion stuff, don't know what it would do to the ozone layer.