Your first notice was nothing you could tag. A strange, subtle background noise of ordinairy things like traffic, hammers, and children’s voices; but from nowhere you could see, until you realized they were all from someplace distant from where you’d never before heard them; way across town; over the hill; beyond the woods. Strange thing was, they were coming from the sky.
Next would arrive a faint and intermittant hum, again from above tho distant and gradually waxing louder in an eerie quiet, because birds had ceased singing. Then, as closer dogs began to bark excitedly you’d notice it: a huge cloud on the horizon floating steadily, until you realized it was more like a mountain moving upon you until you fell into its shadow so huge the entire neighborhood, and town, was enveloped in the chill. From its underside you heard echoes of people’s shouts from below, and from its sides the whir of huge, shrouded fans that swiveled and switched on-off in unpredictable patterns. Overall it seemed a monstrous, adrift sperm whale with flat bottom, blunt at front with stubby “flipper” wings and wide, flat tail with upright “flukes” at rear; that moved at an auto’s speed but, because of size, seemed to hurtle past. Then perhaps you’d remember a name for this: dirigible.
But you’d be wrong.
A dirigible is, essentially, a powered and steerable balloon. Another name is blimp, which when inflated has the horizontal shape of an overstuffed bomb with tailfins, but deflated is just a huge, collapsed bag crumpled over attached engines and cabin. Blimps can be impressive in size, but are nothing compared to dirigibles of old, that to achieve their size had partial or full rigid shells. These had, from 19th into 20th centuries, extensively carried passengers and cargo about Europe and across oceans, where they proved ideal in their ability to carry huge loads for incredible distances with a pittance of fuel. This continued until 1937, when the fiery explosion of the huge Hindenburg ended the era. Despite the horrific consequences of that catastrophe, the industry’s resultant reputation of danger was unmerited, as previous years of safe usage by German, British, French, and US hands belied such accusations. The actual Hindenburg conflagration was likely due to sabotage, together with the unfortunate consequence of having to use explosive hydrogen instead of the inert helium available only in the US. Despite the setback, the Zeppelin Works had subsequently built two even larger airships (never flown) while nonrigid blimps saw extensive US service in the war. But the advance of airplanes obliterated public interest in lighter-than-air travel, seemingly forever.
Until now, when rising fuel costs threatened to make air travel but wistful memories of an era of oil-powered energy orgy. In the interim, however, technologies became available that rendered airships an entirely new breed. Weather was now precisely mapped by sattelites, radar, and other means allowed them to avoid storms and find favorable winds, while computors enabled the most efficient routes and operations. In addition, photovoltaics made possible little fuel expenditure.
CONSTRUCTION. Another difference was of what they were built, with new materials and construction methods the yielded lighter and cheaper vessels. The construction could replace much of the cumbersome, expensive duraluminum framework of previous airships with a exoskeleton of rigid, porous plastic much like styrofoam (as if the hollow bones of birds) and sealed on outer and inner surfaces with sprayed films (and resealed when needed). Aluminum and carbon-epoxy main members were imbedded in the foam to support the skin and, because the voids within the foam were interconnected, the material itself was a huge sponge to be filled with the lifting gas, or compressed air as ballast. The size of these behemoths dwarked even past airships, for such largesse maximized their efficiencies.
LIFT. What most differeniated these from their predesessors, however, was noted in their name: Hydridge (hybrid dirigible), as the craft gained lift by both the bouyacy of balloons and planing action of airplanes, enabled by its stub-wings and (mainly) the hull’s airfoil shape, both of which were also helium chambers. Girdling that hull at front and flanks was a rigid, vertical ridge/strake to damp airflow slippage off to sides and gain efficiency. With the older, conventional bouyancy-only vessels, descent was made by valving off amounts of the valuable helium, which then had to be resupplied for takeoff. A craft, however, with just enough lift to achieve neutral weight when laden could achieve further altitude by minimal airspeed; with the fuel needed still far less than aircraft, and the advantage of unlimited retention of helium. The result was a craft that could fly by bouyancy or planing, or both.
PROPULSION was provided by the 4 duct-fan electric motors, that each also swivelled 360 to maneuver (especially for landings and launches) and when unneeded served as wind-turbines to generate electricity. Emergency thrust was by 2 huge gas-turbine props at rear, also capable of powering generators, and for further savings, the craft could be trimmed to present widened surfaces to a trailing wind and, afloat, be moved by wind as an aerial sailship.
POWER was provided by the vast solar arrays on hull and wings, so well that when these generated more power than needed it was stored, not in heavy batteries but in air, low-compressed by surplus-powered pumps. When additional electrical power was required, this air was valved back thru the pumps to drive their motors that, with switched circuitry, became generators.
STEERING was effected by conventional rudders in the twin vertical tails, augmented by aerilons on the stub wings composed of tapered upper and lower bladders, inflated/deflated by air pumps for extention of either or both. Such action could thus bank, steer, or flap; all of which could be further hastened by selective use of swiveled ductfans.
BALLAST was created with that air pumped into the bottoms of helium chambers that, by compression, also decreased that gass’es lift. This additional wieght (in the air itself and water separated from it) was useful for descents, and to compensate for depletions of fluid fuel. More descent weight was accumulated from rainwater collected in the gutters between hull and strakes and, when valved off thru turbines: could generate additional electrical power.
Thus the craft could be lifted by bouyancy and plaining, propelled by sun, wind, or water, and was a mix-breed of construction which, as hybrid dirigible, was quickly dubbed a hydridge.
NAVIGATION was a complex matter in choosing routes and schedules that best utilized winds and sunlight, avoided storms and ice, and conserved fuel and helium. For these concerns were availed a continuous flow of weather data, and computer programs that could project choices into future trajectories to predict their exact effect. Even with all this, several operators were required to monitor (and press for) each their particular interests, with the captain responsible for final decisions.
LANDINGS were approached from downwind with decreased airspeed that lost lift, with final maneuvering by the 4 swivelling ductfans until the vessel set lightly down upon 4 multi-wheeled pads, and then was tied to ground (or anchored in water) at various hardpoints. If heavier winds were possible, the vessel was kept faced into it, with the simplest method being moored to a tower at nose (as all other airships). If such was available at the site, a long line was dropped from that bow and retrieved by a groundcrew that delivered it to a tower crew who threaded it thru the anchor point, by which the vessel was drawn in and secured. The hydridge also carried its own mooring tower snugged below the cabin while teathered to the nose and, when needed, dropped to hang vertical and lowered to a ground crew who positioned its pointed base to a small pad and then secured the tower by stout guy lines. This ready, the airship could back away and then be drawn to mooring.
CARGO. Within the hulls’ bottom were lateral racks from which hung the containered cargo. These were raised and lowered from above by tracked, rolling gantry cranes and thru a floor opened from flight by scrolling up huge transverse rolls of heavy, translucent film. With but one layer of these containers, each module could be load/unloaded seperately, partly necessary because for each unload a replacement load was required to retain equal bouyancy, and never was the hold completely emptied. Additional cargo was lashed to interior decks fore and aft of the racks, and truly large components (towers, buildings, bridges) were suspended beneath the airship’s flat belly.
CREW. Bridge and quarters were contained in the nose. Each crewmember who worked in unhoused areas wore a backpack parachute and tether clipped to slide along embedded rails on the most trafficed external surfaces. The nylon straps from these clips were spring-coiled (like tape measures) from an additional backpack housing that allowed gradual unreeling but caught at rapid ones after 4 feet. Helmets contained headlights, earphones and mikes, largely so exposed crew could be warned (with addition of many klaxons) of airship maneuvers.
PASSENGERS were accomodated in private, windowed cabins also in the nose, where was also a dining room, lounge, gym, and small theater. Of greater favor among such travelers were an enclosed observatory deck (below bridge in bow) a sundeck on the outside stern fantail that also served as helipad, and a small observation deck atop the hull was a spectacular spot to witness dawns, stars, and sunsets. In calm flight and strapped for safety, customers could also stroll the lengthy gutters between hull and strakes that surrounded the airvessel.
FUNCTION. The use of such a vehicle was for a slow, globe-girdling routes always with prevailing winds for economies of fuel. With cargoes, speed was less essential than cost, tho dirigibles were still far faster than ships and landtravel. These transports could haul containers that were handled quickly and, together with the scant maintenance required for lightly-used powerplants, stopovers were short and the craft were almost always in air, where much maintenance and repair could be handled. A number of circum-planet routes confined each to certain latitudes where they employed trade winds to help their passage and economy, and as some routes girdled the globe in 28 days, crew could tell their whereabouts by the moon’s phase when there.
This fleet of hydridges had taken over most airborne cargo traffic, as well as an increasing commerce of passengers to whom speed was less essential than cost, or who valued the quiet respite of days and nights of floating above shifting land or seascapes. The primary airship carrier was Bouy-Air, an internationally-subsidized industry, with bases around the globe. By passage of its vessels the Hydridge was becoming commonplace, but folk around the world could never completely ignore these artificial cumulous clouds that cast their huge shadows over every land and sea.