The airship finally takes off - Hybrid Air Vehicles has first civil customer | Hacker News Reader

The airship finally takes off - Hybrid Air Vehicles has first civil customer

gizmag.com

40 pointsColinWright23 comments

Interesting to note that the first customer is going to use it to supply remote regions of the frozen north (think Ice Road Truckers). I wonder how these vehicles will perform in sub-freezing weather. Will the helium compress? Liquify? Lose some of their lift? If so, this could prove to be a huge boon to supplying building material and other resources to isolated places that can't support airstrips for instance

Airships are actually more efficient in cold climates. The craft gets its lift from the difference in density between air and helium. As the temperature drops air gains more density (in absolute terms) than helium.

In the early days of airships this caused quite a problem, since it meant you had to vent hydrogen at night when your ship was too light, and then drop ballast in the morning when it was too heavy. As the day progressed the sun would warm up the helium, making the ship too light again.

That's the big benefit of hybrids - since the ship is heavier than air it's tolerant of temperature-induced changes in buoyancy.

The helium certainly won't liquify. The denser air in colder climes will increase the lifting power. The volume of the envelope remains the same, and the increased density of helium at lower temperatures is negligible.

Deleted comment

Not so,

The helium will be denser, but it has a molecular weight of 4 as opposed to ~29.

Suppose it is 20% cooler -- thus occupying 20% less of the volume at equal pressure, thus being 1.25 as dense.

Lift will be proportional to 29 * 1.25 - 4 * 1.25 = (29-4) * 1.25

As opposed to lift at our reference temperature 29 - 4 = (29-4) * 1

Showing clearly that there's 25% more lift.

The bigger problem is if the envelopes collapse, but clever people have already solved this by having an internal bladder filled with air to take up the slack.

The cold would be a problem sure I learned in ground school the temperature drops 1.98C for every thousand feet you go up so it's going to be cold anyway even in the Summer. Although -40C to -60C is pretty cool!

I would be more worried about wind since it's pretty windy up north which makes sense since there aren't any trees or even a shrub to stop it.

Maybe now people in the north won't have to pay $30 for Kraft Dinner and $20 for a litre of milk.

I'd be more concerned with how they perform in high winds. Unlike conventional aircraft that use massive propulsion to cut through the air as quickly as possible, these vehicles are designed to just hang out in the air.

It says they can fly at up to 115mph so adjusting course to compensate for leeway, I imagine they could handle some pretty stiff winds even if it cost them speed.

Probably safer in a storm than a heavier-than-air craft, since the wind won't be able to knock them over and stall them, or steal their lift. Worst you'd have to worry about would be the passengers getting seasick, as long as you can maintain altitude.

From what I read about airships' use in the 1920s, high winds aren't a serious problem, but unexpected storms can be, because they can't maneuver out of the storm's path as well as a heavier-than-air craft. Most of the US Navy's airships were lost to relatively small, local storms if I am remembering correctly. Which would be a plus for high latitude use, since their are fewer storms there.

The US airships were overly susceptible to bad weather because they were based on a wartime German design in which airworthiness had been sacrificed for altitude.

From here: http://sped2work.tripod.com/zeppelins.html

"Unknown to the French and American engineers at the time the height climbers were made from thinner gauge material and, except for the machine guns, stripped of armaments and even one engine. They did not realize they were being specially built in response to mounting losses and were super risky to fly, being very much on the edge of sound structural rigidity. The Americans copied the L-49 almost exactly not knowing how close the Germans had pushed the boundaries of minimal structures and a major reason she, the Shenandoah, broke up in bad weather."

if they didn't perform well in sub-freezing weather, they wouldn't be much use anywhere. as you gain altitude, things generally get pretty cold.

The feasibility of a giant, easily hit target that is vulnerable to almost all forms of attack makes its use as a military vehicle a little questionable to me.

Obvious civilian uses, though.

Militaries commonly use giant, easily-hit vehicles. Aircraft carriers and cargo planes are obvious examples. Militaries find practical use for such vehicles by defending them against attacks.

I doubt the 'tip of the spear' will consist of fleets of large, slow airships. The strategic value in lighter-than-air craft is in their ability to stay airborne for extended periods with relatively little control, and access areas unavailable to traditional aircraft.

Of course, these airships will likely not be able to the perform 'combat landings' to the extent the C130s can.

The gas inside airships is at extremely low pressure so, whilst a large target, they're actually not as vulnerable as one might think.

This is a good point. In WW I there was an AA shell that went off inside a German airship, and the ship was able to land safely. They really are quite resistant to damage.

I have an air-to-air missile and a minigun firing 20mm rounds at 6,000 rpm that beg to differ.

Regardless of pressure, you could turn the entire aircraft into swiss-cheese or blow a hole in it so large you could fly a jet through it in seconds.

Not every military vehicle is designed to be shot at. Even today most equipment is shipped to the battle zone on easy-to-sink freighters.

I've wondered about smaller LTA vehicles being used in tactical situations where rotor-blades would prove impractical. Could a sufficiently nimble LTA vehicle make skyscraper or mountain rescues by navigating laterally to the rescue point? I helicopter will almost always need to have a vertical approach and rescue path because of the large rotors, but an LTA would not be restricted in that way.

It'd get blown around by the wind in the mountains too much to be practical. Most LTA aircraft usually pick a general direction and "head that way", their ability to remain in a single position is limited because it would require a large number of jet powered thrusters mounted at various locations in order for it to be able to fight the wind and hold still.

I don't envy the programmer that has to code the heuristics to keep a zeppelin still in the presence of 60 mph winds.

All photos are renderings. I'll believe it when I see it.

It's certainly annoying and odd that their press pack doesn't include real photographs, but there is a video of one taking off, flying, and landing on http://hybridairvehicles.com/

I'm guessing the surveillance applications are particularly appealing to the military. How long could a drone version stay aloft at high altitude, out of range of common weaponry?

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