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The Rim of Space on Audio

Blackstone Audio have release The Rim of Space on Audio as part of A Galaxy Trilogy VOL. 4

The Mentor

Grimesish Grumberlings, Up, Up and Away

Somehow, over the years, the idea has gotten around that I have a thing about airships. New and again kind friends, chief among whom is Keith Curtis, present me with books, either factual or fictional, in which dirigibles play a major part. The latest of such gifts, from Keith, was Skyship, by John Brosnan. Despite its having been alleged to be well researched I found it both disappointing and annoying.

The cover, depicting the crippled phoenix (that was the ship’s name) drifting, at relatively low altitude, through rather than over New York was remarkably uninspired. These skyscrapers, like matchboxes standing on end, could have been in almost any city in the world. Oh, if you look very carefully you can find the Chrysler Building but the Empire State building (preferably with King Kong clinging to its upper storeys and reaching out a huge paw to swat the aerial intruder) would, at the very first glance, have set the scene. And it would have taken no liberties with the story as Phoenix did foul the Empire State Building during her passage over and through New York.

But why did I find the book annoying?

Quite some time ago Robert Heinlein said, “Only people who know ships can write about spaceships convincingly.” I’ll take this one stage further and say “Only people who know the principles involved in the handling of surface ships know the principles involved in the handling of airships.” It has been said by people who have been making feasibility studies that the personnel for airships, when they make their long overdue return to the world’s skies, will be recruited from the sea services rather than from the civil and military air services.

But how did Mr. Brosnan annoy me?

He should have pleased me by having a naked blonde clambering over the envelope of the huge dirigible when she was over the mid Atlantic. But the lady in question was such a dim bitch that I just couldn’t give a damn about what she was or was not wearing. Come to that, I should not have turned a hair if the equally dim hero had plunged to a watery grave while attempting to rescue her. In fact the only character in the whole sorry mess. whom I was prepared to like was Herr Dressler, the German zeppelin designer. (It was a great pity that he was not among the survivors of the disaster.)

Well, I’ll summarise madly. Phoenix, on her maiden voyage, was returning from England to the U.S.A. Ill-disposed persons sabotaged both her nuclear power plant and the computers which constituted a sort of super autopilot, looking after trim and altitude as well as steering. Helpless in the grip of a gale she blew towards New York.

But there was an auxiliary power plant so that lights and other essential services could be maintained. This plant also provided power to actuate the rudder and other control surfaces. Using these, the airship’s captain was able either to avoid skyscrapers or to reduce contact to no worse than a heavy scrape.

And why am I bitching about that?

Because a control surface, no matter how much you wiggle it up and down or from side to side, is utterly useless unless a fluid medium such as water or air is flowing past it. An engineless airship is no more than a free balloon. Unless she is making way through the air she can not be steered.

A surface ship making her way up river can be used as an analogy. She suffers a main engine breakdown but still has power for her steering engine - but her rudder is utterly useless. She will just go where the current takes her. There is, however, a way to bring her under partial control. In such circumstances an anchor would be dropped, to act as a brake. But suppose that, well downstream, there is a wharf at which the ship might lie alongside until repairs are made. Then the anchor may be weighed until it is just on the bottom. The ship will resume her sternward drift but not as fast as the current. Water will be flowing past her rudder. She can be steered. With a little bit of luck she will fetch up alongside that wharf. Ideally, of course, the river bottom should be soft mud, with no rocks on which the anchor could catch.

The first successful attempt to convert a free balloon into a dirigible with limited powers of maneuver made use of the above technique, which is called dredging. Prior to then people had been fitting balloons with all sorts of sails and rudders - which were, of course, quite useless. And then the Swedish explorer and balloonist Salomon Andree realised that such control surfaces would always be useless unless the air were able to exert pressure upon them. He had to have something that functioned as does the keel of a sailing craft. His “something” was draglines, which decreased the speed of his balloon over the ground so that she was not travelling as fast as the wind that carried her. In 1897 he made en ambitious attempt to reach the North Pole by balloon. It seems that his draglines functioned well enough when they were trailing through the sea but, when he was over the ice, they must have fouled on hummocks and in crevasses.

Over thirty years later his frozen body, with the bodies of his two companions, was recovered.

It might be argued that Dr. Solomon Andrews’ Aereon, flown successfully in 1865, was a free balloon — but she most certainly was not. She was a true dirigible, capable of flying against the wind whereas Andree’s ship could go only with the wind, with limited power of deviation to left or right. The Aereon, one night say, was to Graf Zeppelin as a sailing yacht is to Queen Elizabeth II. Unlike a sailing yacht, however, she could never be becalmed. She made her own wind to act upon her control surfaces. I’ve used the idea of the Andrews Airship in more than one story so I’ll not go into the principles involved at any great length.

It all boiled down to a juggling of positive and negative buoyancy. The flight started with positive buoyancy and weight aft. She did not lift vertically but glided up at an angle. When she reached her ceiling she was trimmed so as to be down by the head and gas was valved. She glided downward. Dumping of ballast and a shifting of moveable weight - the crew - resulted in another upward glide. The division between the cigar-shaped gas cells - three, in one model - functioned as does the keel of a sailing craft. And, as long as she was making way through the air, her control surfaces functioned.

And so, in 1865 and 1897, those two aeronauts with the remarkably similar names realised that a flow of air around control surfaces was essential. It is a great pity that so many Twentieth Century writers - Mr. Brosnan is by no means the only offender - have yet to grasp this.
Originally Published in The Mentor No: 35 - Dec 1981