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Fuelless Flight with Air Submarine?
An anonymous reader writes "Using the same physics principles as submarines, a new company is planning a fuelless air ship. Recent advances in ultra light and strong materials are making this concept a practical reality." There's no question that changes in buoyancy can be used to propel a vehicle, but "fuelless" is going to be tricky.
All the same, it's still a cool idea. I want a small one to fly to work in (maybe add pedals for all the compression-> decompression stuff and you'll have a human powered plane ;)
Looks can be deceiving. Or CAN they?
The idea that an airplane can fly endlessly carrying heavy loads of passengers and cargo without burning any fuel
So far so good.
The new hybrid "gravity-powered aircraft"
Starting to get bogus.
is formed by merging the capabilities of the following devices into a single new aircraft apparatus:
(1) an aircraft capable of aerostatic (lighter-than-air) lift to gain altitude; and,
Still OK.
(2) a glider aircraft capable of aerodynamic lift, having a high glide ratio to accomplish long range gliding; and,
Starting to get bogus.
("Glider"? Using diving planes to add a significant forward component to upward/downward motion is well understood. But a "glider" is something else - a high-speed device with significant aerodynamic lift - initially powered by atmospheric thermal energy in the form of updrafts storing energy by raising a NON-bouyant craft against gravity, then trading this stored energy for momentum as necessary by gliding downward. Raising a neutrally-bouyant object stores no energy.)
(3) a (patented, new design of Robert D Hunt) wind turbine that is capable of harnessing the force of wind to generate power as the aircraft glides downward. This cycle can be repeated indefinitely to allow the craft to stay aloft virtually forever.
Bingo! Perpetual motion.
You CAN get a lot of forward motion out of lift-driven vertical motion. But it takes ENERGY to adjust the lift. The submarines described in the original Slashdot posting are one example. Zepplins with diving planes that achieved speeds in excess of 200 MPH by this mechanism also existed in the mid 20th century.
But the Zepplins BURNED FUEL to change their bouyancy (by heating some of their bouyancy gas), just as the submarines use energy to compress or expand gas in their bouyancy tanks. This makes them a heat engine (though a slowly cycling one) and subject to the carnot cycle limit.
This craft proposes to use a turbine to collect energy from the wind of its passage and use that to adjust its bouyancy, use the bouyancy to produce forward motion, creating the wind to drive the turbine. Like a generator with its shaft connected to a motor which is also wired to its output, the energy goes around and around, with some being lost in every pass.
This is not to say it won't fly at all. But to the extent that it DOES fly it's getting its basic power from vertical air currents, just like any other glider. By being nearly neutrally bouyant it sacrificed the ability to store energy in the gravitational potential of its own weight at altitude, and it's replacing that by being able to convert the wind of its passage to stored electricity, then feed that back into forward motion via bouyancy adjustments rather than propulsive fans.
But I expect this to be more expensive and less efficient than other alternatives - such as an equivalent modification to the original 200-MPH zepplins WITHOUT the fixed wings.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
My goodness, that video is so verbally twisted virtually anyone not having a clue would buy into it.
Of course that is the intent. Their perpetual motion is a complete farce. If you listen to the explanation (I know, it's ludicrous) they're basically saying you can get more air going down then you can going up.
Some other fallacies is the "lighter than air" effect. If you've ever seen a blimp, then you realize the size this craft would have to be in order to carry even the lightest loads. Helium is only "lighter than air" when it's density is lower. This is the whole "which weighs more, a pound of lead or a pound of feathers" argument.
Along those lines, you'd also need to take into account the expansion effect. Let's use weather balloons as an example. The higher they go, the bigger they get. Air pressure drops as you go up, therefore the greater air pressure in the balloon expands it outward. If it didn't, then the balloon would reach an equilibrium and go no higher. This craft would need to also take this into consideration. This could be quite a technical hurdle, gliding an aircraft that is constantly changing dimensions.
Regardless, the craft would at least need to carry some onboard power source.
I take this "article" with a big salt lick.
~X
Random Quote:"If it's too good to be true, then somebody is getting rich and it isn't you."
~X~
>To be safe they re-ran the numbers three times to be absolutely, positively sure the refuelers hadn't made any mistakes; each time using 1.77 pounds/liter as the specific gravity factor. This was the factor written on the refueler's slip and used on all of the other planes in Air Canada's fleet. The factor the refuelers and the crew should have used on the brand new, all-metric 767 was .8 kg/liter of kerosene.
Lessons: a triple-check doesn't help you if there's a systematic error. Standardized measurements are a Good Thing.
>the EICAS issued a sharp bong--indicating the complete and total loss of both engines. Says Quintal "It's a sound that Bob and I had never heard before. It's not in the simulator."
Lesson: in a safety-critical system, train the users for "impossible" situations.
>Hydraulic pressure was falling fast and the plane's controls were quickly becoming inoperative. But the engineers at Boeing had foreseen even this most unlikely of scenarios and provided one last failsafethe RAT.
Lesson: when your engineers go paranoid, if there are lives at stake then for God's sake listen to them. "Belt and suspenders" engineering saved lives in this incident.
>Quintal "got busy" in the manuals looking for procedures for dealing with the loss of both engines. There were none..
Lesson: learn from experience. There have been incidents, like volcanic ash injection, that have forced shutdowns of all engines on a jetliner. If your statistics say the engines can't fail at the same time, and the graybeards say they can, then you left something out of the statistics.
>The avoidance of disaster was credited to Capt. Pearson's "Knowledge of gliding which he applied in an emergency situation to the landing of one of the most sophisticated aircraft ever built."
Lesson: there is no substitute for a wealth of experience. Downsize your 20-year veterans to save money, watch things go wrong.
Sorry for the diversion, but these are things I'm passionate about.