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Sky Yacht

An unpowered dirigible flying two kite-sails, an upper and a lower, into differing wind currents to achieve motion in a manner similar to a sailboat. Each kite-sail also has its own integral LTA component.
  [vote for,

To take off from the ground, a lightweight hydrogen/air jet engine trolling-motor is used to bring it up to the optimum radar-sensed altitude, in between two disparate wind currents. One sail assembly is allowed to drift upwards the other downwards. Sails unfurl to the calculated extent once they reach position.

To land, the sails are furled and the kite-assemblies drawn back to nestle with the main dirigible. The trolling motor then takes over maneuvering and propulsion duties to expedite touchdown.

In between, everybody enjoys a scenic flight that is not only quieter than a hot-air balloon or sailboat, but almost always faster than both.

Ah, but a)the kites are joined to each other in a straight line bisecting the dirigible and b)that line will never actually be horizontal or even at a consistent angle between journeys, therefore c)the passenger compartment will always have sloping floors. Not so...

The dirigible's LTA component of (say)6 sausage-shaped gasbags surrounds the circular passenger/crew compartment. While the outer portion of the dirigible rolls to accomodate the kites' deflection angle, the floor of the passenger compartment (when unlocked) itself rolls, remaining "down" at all times. This has the added advantage that the ship has a maneuvering-friendly CG, unlike most dirigibles which are very bottom-heavy.

(Alternatively the kite cables' collar could rotate on the outside of the dirigible, but I think a self-stabilizing floor is a lighter, therefore better, solution)

The one disadvantage is that, unlike a powered dirigible which rarely has a very noticeable angular offset between apparent and actual movement, the craft's nose will be pointed in whatever direction is normal to the kite-sails' cable, with little relation to direction travelled, ie: rarely straight-forward. Solutions are in the works.

[yes, I realize this is one of those ideas that everybody thinks of: I just decided to post it]

FlyingToaster, Apr 23 2013

basic concept also in the annotations of Zepplins_20with_20rigid_20wing_20sails
[FlyingToaster, Apr 23 2013]

concept sketch http://s68.photobuc...1203161091286551378
[2 fries shy of a happy meal, Apr 23 2013]


       The basic concept of floating in the air is that you always move with the wind. Period. In a different medium such as water, if you were fully inside it, you would move with whatever water-current was flowing. Period.   

       At the interface of such media, you can use the keel of a boat to offer resistance to the wind. That lets you bounce air off a sail such that you become able to move your boat in some other direction than "with the wind".   

       In theory an "air keel" that was big enough could offer resistance to a current-flow, and so an underwater equivalent of a sail could let your "taob" ("boat" backward) move in some direction different from the direction of water-current flow. But I wouldn't count on it, simply because air so feebly resists anything, compared to water.
Vernon, Apr 23 2013

       [Vernon] there's no //air keel//, it's two identical sets of kite-sails being set into two differing velocity air streams. It would work **better** than a keel set in water when you set one against the other.   

       (not perfect of course: the main dirigible, which would be probably positioned somewhere between the two streams, and cables have a fair bit of drag in the air compared to a boat in the water)
FlyingToaster, Apr 23 2013

       [+] because the idea is workable in principle, and seems to me likely to require gigantic-scale material engineering, one of my favorite subjects. Working out the estimates needed to know if the idea is even vaguely feasible is challenging, though. For starters, you need a good source of high precision, small scale, 3D wind velocity data. There’s plenty about persistent, large-scale wind – the major atmospheric “cells”, which are on the order of 3,000 km wide and 10 km high – but stringing together parasails many 10s of km apart seems dauntingly unfeasible. I simply don’t know if greatly different winds – ideally, winds nearly equal in magnitude and opposite in direction, relative to the ground – exist with any reliable regularity on the scale of a few 100s of meters that practical kite/sail technology could use.
CraigD, Apr 23 2013

       (responding to [21Quest]'s anno)

       Any differential sailing system consists of 2 planes, joined somehow, each immersed in a different velocity(= speed & direction) medium.   

       It's the joining method and the media that make the difference.   

       Imagine a sailboat with no hull, consisting only of mast and keel, both magically of equal density to the air and water respectively. In order for this to operate at all a counterweight is needed on the windward side or the thing simply tips over. (We've all seen or experienced crewmembers hanging off the windward side of sailboats).   

       Now imagine, instead of a mast, a rope or rod with a plate at each end like a Star Wars' Tie fighter (though somewhat lopsided since the keel is smaller than the kite), both of which can be wiggled around. This is a kite-sailboat: it doesn't need a counterweight.   

       (The only difference between rod and rope is that a rod can do its thing under compression as well as tension).   

       Now, instead of air-stream vs. water-stream we'll try airstream 1 vs. airstream 2. It's the same thing as a kite-sailboat except the "keel" portion is just another sail assembly.   

       Of course the other big difference is that water current speed is so insignificant it's generally regarded as being stationary. With two differing wind currents you get *both* working for you.   

       Or, to answer your question, yes, same thing except for the sails aren't mounted like fins, they're more like kites as far as attachment points are concerned.   

       (and to [CraigD])

       It's more complicated than water-sailing of course, but the major additions are the necessity of using radar to "see" the streams, and awareness of aerodrag (since a dirigible is larger than a ship for the same carrying capacity). Pretty much exactly like flying two kites at the same time.   

       A remote-controlled demonstrator could be as simple as a couple hang-glider sized sails (equipped with servo-driven trim tabs), joined by a clothesline, tossed off a low-speed aircraft between two airstreams, navigated by using ground radar to plot and follow a course.
FlyingToaster, Apr 23 2013

       Ok, I'm having difficulty picturing this. Here's a sketch [link] of what I think you mean, (minus the susage shaped bags), is it even close?   

       umm.... let's see: if the sails were kite-y rather than parasail-y, and attached to either side of a cigar wearing a dog-collar, that would probably cover it in general.   

       I like your donut idea for a large passenger-liner craft or at least a streamlined version of same: the swivel avoids the angular offset between perceived and real direction of flight as well as allowing for naturally level floors.   

       What is it ? (I noticed quite a number of views so I assume it's an earlier drawing ?)
FlyingToaster, Apr 24 2013

       Nope I just drew it. It's what I had in my head after reading your idea, except that I thought you had arranged the sausage shapes end-to-end to form the ring.   

       I figured that suspending it from a central swivel rather than a rotating collar would solve most of the rapid direction change problems the kites would be causing and it would keep the floor level at the same time.   

       Neat! at least I can stop thinking "hmm... rotating sky restaurant ? hurricane eye viewing platform ?" etc.   

       The donut seems a natural for a large transport/passenger craft where the weight can be balanced, and looks good too.   

       On a small craft (1-2 people) maybe something like an egg-timer on its side: two gas bags joined by a strut, in the middle of which is the swivel, one envelope for the people, the other for the engine and cargo.   

       (pardon mytyping: I just installed the latest firefox and it feels the need to stop and read and write to disk a few hundred times each and every character I type)
FlyingToaster, Apr 24 2013

       Ages ago I thought of a 1-2 person dirigibly LTA craft consisting of 6 sausages around a lightweight deck, with a VW engine; useful for thumbing one's nose at rush hour traffic. Problem is engines aren't light.   

       This'un however uses a lightweight jet engine, and that only for making landing & takeoffs (and occasionally changing airstreams) easy. And powered by hydrogen (Helium is soo passe). A couple hundred yards of clothesline won't weigh much. Though I guess a radar unit sensitive enough to pick up wind direction and speed of various altituded airstreams might not be so light.   

       Kite-sails work, so this should... but I'm having a hella time working the math or even a crude example.
FlyingToaster, Apr 25 2013


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