HUSH Loves Airships, Part 3

Twice now I've taken to my CR4 soapbox to proclaim, "This is the airship of the future!" The first was back in November 2012; the second was this past March.

Almost certainly, my desire to see new life breathed into an obsolete mode of transportation is heavily nostalgic and novelty. They fascinated me as a kid on the rare occasion I glimpsed one. As an adult, they serve primarily as billboards, but they are also a faint reminder that I once recognized them as something more than that. Blimps and airships were once the truest form of airliner; they melded luxurious accommodation with efficient service and travel. Today, 'airliner' refers to company who charges you per cracker served mid-flight.

So I won't argue that airships are coming back or that they have a bright future. Rather, let's examine how one peculiar type of theoretical airship could push aerospace material science to new heights.

Enter the vacuum airship. This type of aircraft is considered the first concept of a flying machine that, if built, could actually fly. It was devised by the Italian monk Francesco Lana-Terzi in 1686, who was a professor of physics and math. He was inspired by the atmospheric pressure work of Otto von Guericke, developer of the vacuum pump, and utilizing his scientific knowledge he envisioned an airship whose balloons were completely empty.

Lana theorized that he could construct a boat-like vehicle tethered to four evacuated spheres, with a sail and rudder for sailing. The craft would float until the density of the atmosphere counter-balanced the weight of the ship, and it could be landed by letting small amounts of air into the spheres.

There were several reasons Lana never built his airship. He believed God wouldn't let such a device succeed, on account it could grant an insurmountable advantage to armies. He also pledged himself to a life of poverty as a monk, so he could never amount the resources required.

Oh yeah, he also had no clue what to make it out of, and this represents the same problem with vacuum airships today. The vacuum tanks would need to withstand enormous atmospheric pressure once evacuated. While modern materials can overcome this structural load, it can't be done without weighing down the vessel to a non-buoyant density.

Of course, researchers and scientists have had 300 years to solve this problem, right? Yes, but virtually no attention has been paid to this reliable concept. Once Portuguese priest Bartolomeu de Gusmao nearly burned down the royal palace while demonstrating a successful hot air balloon, vacuum-based atmospheric buoyancy lost all interest.

As sustainable engineering and resource management become integral routines, not just chores, many ideas once considered impractical are revisited if they can be efficient. Obviously, blimps need large amounts of helium or hydrogen to remain buoyant, but helium is in low supply and expensive while hydrogen goes boom. But a vacuumed structure would create static lift which can be drawn upon to fly almost anything. And this is 2014, the age of supermaterials--graphene, aerographite, buckminsterfullerene--something has to be able to support this extreme pressure, right? And even if such an invention isn't used for a vacuum airship, it could be practical for thousands of other applications. Entire floating cities could be a reality and flying cars would require minimal energy resources.

So far, the closest we've gotten is a three-layer shell with a low-density core of aluminum honeycomb or ceramic foam that is between two ceramic sheets of boron carbide or silicon carbide. The initial research suggests that thousands of 10 cm or smaller balloons could be constructed and harnessed to deliver lift to a vehicle or platform. While not useful quite yet, there are developments being made. Perhaps the most interesting case is for carbon nanotubes that have buckminsterfullerene caps. If they could be manufactured in a vacuum and produced on a large enough scale, they could provide captured static lift.

Even though vacuum airships were obsolete before they were even realized, they continue to forge presence in the aerospace industry. Just because it wasn't built, doesn't mean potential real engineering solutions are valueless.