Splattering Guts for Fun & Profit

 
Speaking of gasbags, no sooner does some fool* write a column totally dissing giant airships than this video clip turns up:



That, my friends, is the prototype Lockheed Martin P-791. Is it a fast blimp? A modern dirigible? Actually, they call it a Hybrid Air Vehicle.

No, that doesn't mean it's powered by Prius engines. (Although the thought of covering the topside with some kind of thin-film photovoltaic array does suggest interesting possibilities.) Rather, it gets some of its lift from the helium in the gas envelope, and depends on ducted fans to get off the ground, but while in forward flight at speed also gets lift from the shape of the gas envelope, which acts as a lifting body. If the engines were to cut out it would (hopefully) settle gently to the ground, but by design the thing can stay aloft for periods measured in weeks, as long as the engines remain working.

To me, of course, the most amusing aspect of the P-791 is its feet. It doesn't have conventional landing gear. Rather, those four foot-like pods are built-in hovercraft, which enable it to land on and take off from just about any flat surface, including water or swamp muck. Reportedly the fans in the feet are reversible, too, meaning they can stick to the ground like giant suction cups, if needed. (Presumably this would be a bad idea if you'd landed on, say, water, desert sand, or a beach at low tide. Unless you also wanted to have the world's largest clam-bake.)

My understanding is that this beastie is the result of a DARPA RFP for a long-range flying machine that can carry an entire infantry brigade, along with all of its equipment and vehicles, loaded for bear and ready to deploy anywhere in the world on a few hours' notice. Reportedly the design can be scaled up to carry cargo loads measured in hundreds of tons, so so much for that fool* who so rudely disparaged the idea of airships "the size of ocean liners."

Still, no design is without its drawbacks, and this concept has a significant one: because the gas envelope also functions as a lifting body, its shape must stay within a pretty rigidly defined set of parameters. Because a flexible gas envelope's shape is in turn a function of the balance between interior gas pressure and exterior atmospheric pressure, this limits the operational ceiling. Lockheed claims the design can soar up to 20,000 feet, and I've no doubt they're absolutely right, but other sources say 10,000 feet is a more realistic practical limit, which puts it well within range of even older shoulder-fired anti-aircraft missiles. So I don't think you're going to see fleets of sky-battleships anytime soon.

But still, as fodder for the sci-fi writer's imagination: ain't it cool?

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* me