In my simpleton mind, I cannot understand why we do not use more blimps for transporting goods. Seems engines and fuel could be done with solar, also seems like they could be automated. Is it simply not cost effective? Is it dangerous even though modern blimps use helium? Eli5.
In: Engineering
A few things.
1. They are quite vulnerable to the wind but cannot fly as high as the jet powered aircraft.
2. The balloon need to be quite large, and it as an issue. A FedEX blimp base would need to be massive.
3. They are too slow.
Blimps can only be used in good weather. When that’s not available, your shipment is grounded. That sort of unreliable transport only works in a few industries, and they use trains for it. Blimps are very expensive relative to trains (though so are trucks).
We don’t use solar/electric for planes either, because Lithium batteries are really heavy and solar panels don’t generate nearly enough power. Solar is good when you can have acres of it soaking up sunlight all day long, it’s not effective at powering a vehicle.
Electric or gas, planes just work better. They’re **way** faster, and their forward speed directly generates lift so they can carry more than a balloon too. Planes are already mostly automated, as much as a blimp could be (I assume).
Finally, not much get shipped using planes either. The vast majority of global shipping is on ships, and then trains. Air is used when speed is worth the higher cost – we don’t need a cheaper, slower air option.
Blimps are simply bad as flying machines. Also there is no way for the solar panels to make enough energy to completely eliminate the need for external charging, though they could indeed extend range.
But this takes us back to our first point. Why do we have flying machines? Because they can carry a lot of people and a decent amount of cargo across vast distances **quickly**. Speed is their most important attribute, otherwise trains and ships would completely eliminate the need for aircraft. But blimps are bad aircraft. Yes they can fly but with several limitations. They cannot go as fast as planes, in fact they’re slower than a slow plane going slow. They cannot carry a lot of people compared to their size, not that people would opt for a blimp over an airplane aside from the novelty factor because they’re slow, and they can’t carry a lot of cargo, at least relative to their size, and their size absolutely is a problem because that makes them expensive to make and to store. They’re also at the mercy of weather conditions much more than airplanes are, and they can’t easily fly high enough to avoid bad weather.
Basically nothing about blimps gives them an edge over conventional aircraft other than perhaps their fuel use.
Veritasium made a video about this question recently. Well worth watching.
One of the main limitations, is for them to be big enough to replace trains/ships and haul cargo, they’d need to be massive. It’s also very difficult for an airship to hover in place to allow loading/unloading of cargo.
In addition to what other people said. When it comes to blimps or zeppelins, 90% of the crafts volume is taken up just by the lifting gasses. That is just *not* efficient compared to a jet, container ship, or truck.
Solar power requires a lot of space to produce a large enough amount of energy to run a decent sized motor. That’s why you don’t see solar powered cars or planes.
We stopped using airships because they need extremely large hangars to maintain them.
[Compare the size of a Boeing 747 to the Hindenberg](https://www.airships.net/wp-content/uploads/hindenburg-747-comparison.jpg)
Think of the building you would need to house something that big.
The Modern Goodyear Blimp is actually around the same scale as a 747 but carry much much less.
Helium is also expensive and usually only as a byproduct of fossil fuel manufacture. Also in a few disasters it suffocated the crew.
Hydrogen is also flammable.
Both are hard to keep contained as they are tiny atoms in tiny molecules.
“Hello, airplanes? It’s blimps. You win.”
Kinda sums it up honestly.
They’re slow, have very low lifting capacity, often depend on an extremely scarce resource (Helium), are not very maneuverable, can’t handle a wide range of weather conditions well, take up inordinate amounts of space anywhere they need to land, and plenty more.
It’s a matter of weight and area. Let’s do the math on this:
Vital stats on the [Hindenburg](https://en.wikipedia.org/wiki/LZ_129_Hindenburg):
* Length: 245 meters l(4 times longer than an [A-380](https://en.wikipedia.org/wiki/Airbus_A380)
* 40 m wide (about half as wide as an A380))
* Engine power: four 890 kilowatt engines, total of 3.6 megawatts.
* Top speed: 135 km/h (85 mph)
* Carried 50 passengers, 40 crew, and their food baggage and furniture plus 12 tonnes of cargo, so ballpark estimate 30 tonness total carrying weight.
[Typical commercial solar panels](https://www.goosolarpower.com/2023/06/solar-panel-weigh-size.html) generate 150 watts per square meter under absolutely ideal conditions, closer to 50 W/m^2 on average. To produce an average 3.6 megawatts you’d need 72,000 square meters of them. Given its length and width, the surface area of the top of the Hindenburg is about 5000 m^2 — so it’s about **14 times too small** to carry the solar panels needed to power it — and that’s assuming perfectly efficient electric motors.
Residential solar panels weigh about [9 kg/m^2](https://www.goosolarpower.com/2023/06/solar-panel-weigh-size.html), so 5000 square meters worth would weigh about 45 tonnes. Residential panels don’t have to be particularly lightweight, though, so it’s possible we could bring the weight down to the 30-tonne cargo capacity of the Hindenburg. But we wouldn’t have any weight left to carry batteries. Or cargo.
So the problem is the largest aircraft in the world ever built (by surface area) is way too small to carry our solar panels. But making an airship even bigger than the Hindenburg doesn’t help: the solar power goes up in proportion to the surface area of the airship, but so does the air drag.
One thing that might help is to **make the airship go slower**. Power needed to overcome air drag goes like the [cube of airspeed](https://en.wikipedia.org/wiki/Drag_(physics)#Power), so if the airship went 2.5 times slower than the Hindenburg, it would need 15 times less engine power and we could fit the required solar panels on the airship. But that would put its top speed at 50 km/h (35 mph), only a little faster than a [cargo ship](https://www.marineinsight.com/guidelines/speed-of-a-ship-at-sea/). But going this slow would make it completely **unable to fly into the wind** if the upper-air windspeed was faster than this — which it almost always is — and completely **unable to land safely** if the ground-level winds were faster than this — which they often are.
This isn’t unique to airships. As a general rule, **none** of the combustion-powered vehicles we’ve come to rely on can run on solar panels on their roofs. Not airships or planes or cars or ships, they all are too small to carry enough solar panels to power them continuously, usually by a factor of 10 or more.
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