Saturday (September 1) at 1430: Airships: the Reality
Panelists listed in program: publius, Lisa Hayes, David Malki, Howard Davidson, Joseph P. Martino
Disclaimer: These are my notes from the panel and my own, later thoughts. I often was unable to attend the entire panel, and also chronically missed panelist introductions. When possible I try to note who said something, but often was unable to. Also, unless something is in double quotes it should be considered a summary and not a direct quotation.
What is an airship? Something that moves through air as a normal ship does through water and stays within the air without the application of power.(e.g. airplanes are not airships.) There is no such thing as “lifting gas” – there is buoyancy and objects that are not as heavy as the air.
The lowest anyone has ever gone in a zeppelin is 400m below sea level, by going over the Dead Sea. This was prior to WWII and meant that the zep went further below sea level than submarines could go at the time.
– going into basic engineering/math about why airships actually work. –
1917 highest a zep has gone during a night bombing run, pursued by British fighters. 34,000 feet at best.
The size of an airship versus life has to do with the gravity versus density of the atmosphere. If the atmosphere is thin the balloon has to be much bigger. Denser atmosphere equals smaller balloon necessary.Max you can life with a balloon is 80 lbs per 1000f^3. You need something big enough to carry a power plant to drive it. Of course, the bigger you go the easier it is to get that weight allowance because volume increases faster than surface area. PLUS the bigger your ship the less air resistance there is relative to its size since air resistance is proportional to the length of the blimp squared.
Alberto Santos Dumont – brazillian aviator pioneer
Historically airships have come to grief because they are huge, light, and fragile. And then filled by gases that burn really well when mixed with air. First ship to be filled with helium was in 1921, US (United States C7) airship. Helium was incredibly expensive and unknown until the late 1800s anyway. Helium also provides less buoyancy because it’s heavier than hydrogen. Hydrogen is easier to manufacture as well. (The C7 contained most of the helium supply in the world at the time. The US Navy had only enough helium to fill one air ship at the time. The two airships were called the Shenandoah and Los Angeles, only one of which could be in the air. When the Shenandoah was lost, the Los Angeles couldn’t fly for some time due to the loss of all that helium.)
Steering the airship is mostly accomplished by getting the air to push on the envelope. You have to turn the rudder to turn, then put it back straight before anything at all seems to happen. To avoid an obstacle you have to turn the rudder back and forth quickly and it makes the ship wiggle. This is completely different from piloting in heavier than air. When you turn the engines off it stays in the air! Historically, you had to have thousands of men pull the airship down with ropes.
Then mooring masts.
All sorts of accidents caused by dropped ropes.
It’s much easier to be dragged in an airship than to drive it anywhere. Changing directions is very hard.
Mass balance changes constantly – burning fuel makes you ship lighter. Moisture makes your envelope heavier. You don’t want to rise uncontrollably because it’ll make your envelope expand and lose gas. Airships fly with the nose pointed down since that keeps it from drifting up, keeps it in a mostly straight line.
You can stall an airship and it’s BAD. There is a particular angle that will cause them to stall. (And it’s so different from heavier than air flight that people don’t know how to take it.)
Ripping the envelope is bad. Very bad. (Only a major problem with non-rigid airships.) The zeppelin is a rigid airship.)
There was a design for an airship that had a hangar inside that could house five small airplanes, to be launched and recovered in flight.
I had to leave the panel halfway through.
But. Well. That one was sure a thing. The part I took notes on? That was basically just one guy talking. Rapidly. With flip charts. (I think it might have been publius, but all I can say for certain is that he wasn’t Lisa or David. I know. My namefail.)
It was all very interesting, to be sure. I wasn’t just taking notes for my health. It was good to get in the history and the basic mechanics and the technical detail. But after a while I started to feel like I was sitting in on someone’s dissertation presentation about the history of airships. For all I know, maybe that’s what it was, and the man speaking was a world-renowned expert in the field.
It was just… strange. And there was obviously not a whole lot of discussion.
Which is also why I have little else to say. Other than… flip charts?