🌐 Flying Around the World in under 80 Days Avis LXXX: an Autonomous Airship Drone
Is it possible to complete a trip around the world with an autonomous drone? And under 80 days? Today we will explore this crazy project that would make Jules Verne proud. And we will try to figure out if it can be done with a relatively modest budget.
An autonomous airship. Source: Nano Banana based on a sketch by the author.
🚧 The Project
For starters let’s review how crazy the idea is by answering a few questions that may be popping into your head.
How fast does it need to go? First, we want to build a flying device that can autonomously circumnavigate the world in less than 80 days. If it went on a straight line around the equator the trip would take 40,000 km, or 25,000 miles; in 80 days average speed comes out as a little bit over 20 km/h (13 miles/hour). In what follows we will use meters per second; so 6 m/s will be our minimum speed target. Let’s make it 10 m/s to have some room.
Can we make flight more efficient? The biggest energy expense for a drone is usually not moving about, but staying up in the air. For our little project it will need to keep running for many weeks. One solution I’m particularly fond of is making the aircraft buoyant on its own. An airship can remain afloat as long as it holds its lighter-than-air gas inside. The obvious solution is to propel the drone using electric batteries, and replenish the power during the day using high efficiency solar panels.
This is not farfetched: people are flying solar airships today. Source: YouTube video from eBlimp.
What is the best option for the gas inside the airship? Helium is the usual choice, but for a drone where no human lives are endangered it may not be optimal. Hydrogen is cheaper, lighter and more readily available. Any risk of conflagration can be mitigated by careful construction.
What kind of enclosure is needed to hold the gas inside for 11 weeks? This was solved more than a century ago with clever construction, and modern materials make it even easier. The enclosure can be made strong and resilient while keeping it light by using composite materials. There are readily-available polymers with low hydrogen permeability such as PVA or EVOH, and they can be supplemented with other layers that prevent ultraviolet damage and weather corrosion.
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