Wednesday, 16 July 2008

Airships: Apples, Oranges, and Bananas

The Stella Artois badged Zeppelin NT will be floating over London this summer - anything to get people to look skywards is a Good Thing but then I am "air-minded".
To celebrate this today's Daily Mail has a feature on rigid airships and their accidents. "Oh, the humanity!"

A bit of airship background. There are three sorts of airship:

1 Rigids, like the Zeppelins, the British R100,101, the American Akron and Macon which had a metal (or wooden in the early Schutte-Lanz types) structure covered by canvas into which separate gasbags were fitted;

2 Non-Rigids, or blimps like the Goodyear Airships, the British WWI SS Zeros, or the Skyship 500 which have an envelope containing the lifting gas and one or more air-fillable ballonets to maintain the shape and rigidity of the envelope as the gas expands due to temperature and air pressure;

3 Semi-Rigids, like the Zeppelin NT, Norge or Italia which have either an internal or external keel to aid rigidity to the envelope.

Although the airship will not be flown in wind greater than 25 knots or when it is raining, those constraints are largely due to ground handling and visibility problems rather than any design limitation in the airship. Which is why I found the final paragraphs puzzling so I fisked it in red:

"But even before the Hindenburg, question marks were being raised. Helium was non-flammable, yes, but helium-fuelled airships were also fragile and had a chequered history.
Of four American-built (rigid) airships, two ditched in the sea and one was wrecked in violent winds. (The German-built Los Angeles flew safely until retired.)
The British used (hydrogen-filled) rigid airships for passenger mail, but our airship programme came to an end after the appalling tragedy of R-101. France and Italy had similar experiences.
Yet somehow the airship is too seductive a vision for people to give up on it. It floats like a butterfly as it travels quickly (? 80 knots max) and silently to its destination.
Helium-filled airships such as the Stella Artois Star over London have yet to prove themselves in bad conditions. " (Er, the USN flew helium filled patrol blimps in all weathers for many years until withdrawn in 1961 for policy reasons with a commendable safety and availability record. See the K, M and N classes)

N Class Blimp

So comparing the helium filled Zeppelin NT with the hydrogen filled Hindenburg is like comparing apples with oranges and not factoring in eighty years of technological improvement (compare a Dakota with a 787) is bananas.

Two great websites about airships Airship Heritage Trust and Airship Association.

Up Ship!

I remember an afternoon years ago when I worked in Manchester near to both Old Trafford grounds. Anyway, the Test Match was on and a Skyship 500 was floating above the ground as a camera ship. I happened to watch this beautiful sight from my desk for a while until I felt with my sixth sense the presence of evil nearby. Turning round, I saw the bald, bespectacled Grade 7 who had assumed the role of making my life a misery. "You're not paid to look out of the window. I've been watching you for five minutes." Just who was wasting more money, you twat?


Quiet_Man said...

They may not be practical, though that in itself is debatable, but they are beautiful.
It would be a real pleasure to see more of them in our skies.

Gallimaufry said...

Agreed, quiet man. They are ideal for any task that involves a long time on station where high speed is not important.