At Anumá Aerospace, we haven’t really focused our attention on our airship competitors – we feel that in order to decarbonize aviation, it’s “all hands on deck” time and there are use cases for airships such as heavy cranes, luxury cruises, and logging that are better served at this time with static lift provided by helium. Helium airships are definitely better than any of the heavier than air and high-emissions ground transportation systems in operation today. We applaud their projects and wish them all well.
However, we do need to be clear about the advantages of partial vacuum lift over helium, and to address the question of why it’s not been done before.
1) Helium is expensive.
We’re talking about $7.57 per cubic meter, according to the USGA¹. The Airlander 10 is reported to use 38,000 cubic meters of helium, which works out to $287,660. The CargoLifter project used 550,000 cubic meters – its load rating was 160 tonnes – which would have required a whopping $4,163,500 to fill.
Vacuum is certainly not free…but its costs are the vacuum pumps and the energy to run them. These costs are not tied to any commodity market.
2) And it leaks, so does need to be topped up regularly.
This is an important point on its own and is the reason very long station-keeping missions such as communications and surveillance for the military haven’t been successful using helium aerostats and balloons.
Helium is a very small molecule, and it is lost at a rate of .00025 cubic meters per square meter per day². Consider the size of the envelopes of the ships, and you can see that helium loss is a significant problem.
When the vacuum lifting cells need less pressure, we just run the vacuum pumps.
3) It’s also nonrenewable.
When it leaves the lifting cell it leaves the planet…forever gone.
Air – and the lack of it – are plentiful.
4) The source for helium is not green.
There are emissions in the production of helium, and it is extracted from natural gas.
As long as the energy used to run the vacuum pumps is green, vacuum lifting cells are green.
5) Helium airships are hard to maneuver.
Because helium is so expensive, airship pilots don’t want to release any helium, so changing elevation becomes a difficult maneuver.
With a vacuum lift system, changing elevation is as simple as letting a little air in or pumping more air out. This is similar to how submarines work – except in an ocean of air instead of water
6) Helium airships are hard to land.
In fact, most aren’t going to land at all. Instead, they use cranes to lift cargo, and/or tether to a mast, and require large ground crews for handling.
A vacuum lift system can let air in to land and taxi like an airplane, eliminating the need for infrastructure or ground crews and allowing usage in both traditional ports and empty fields.
So why hasn’t this been done before?
What’s lighter than helium? Hydrogen – but we can’t use that, because of flammability. Also, it has many of the same problems as helium. There is very little “green” hydrogen available, it’s expensive and imparts the same maneuverability and landing issues.
What’s lighter than hydrogen? NOTHING!
The concept of vacuum lift for airships was proposed in the 1600’s by Francesco Lana de Terzi³ – you can see this drawing at the Air and Space Museum at Dulles in Washington DC. However, until now it’s been impractical and perhaps even considered impossible to build a cell strong enough to withstand the pressures of the atmosphere and which could lift its own weight, let alone the weight of an airship and cargo.
With advances in strength and lightness of modern materials, James Little realized it could now be done. He invented an innovative structure which brings the gold standard of vacuum lift into practicality. His patent has been published and we are building on proof of concept models and testing out materials.
White paper can be found here: https://docsend.com/view/xfqgysxy6hj77fb3
Published patent can be found here (and also at the US Patent office): https://docsend.com/view/wc9atk6j2z8gsda8
1) USGS Online Publications Mineral Commodity Summaries 2021 *Helium (usgs.gov)
2) Bonnici, M., Tacchini, A. & Vucinic, D. Long permanence high altitude airships: the opportunity of hydrogen. Eur. Transp. Res. Rev. 6, 253–266 (2014). https://doi.org/10.1007/s12544-013-0123-z