APR 11

if you read their site and apply a little common sense, you'd realise they are run of the mill frauds. If you need to use special mathematics that you have devised just to 'prove' your concept that you have not built yet will work, then your inventions only will work where you dreamt them up: in your head, and nowhere else. Come on, if it sounds too good to be true, it probably is.

I would have to agree, that this sounds very fraudulent. "Requires no fuel" but pumping hydrogen in and out of tanks takes energy. Where is this energy coming from?

I'd love it if this is a practical idea. But I doubt it.

The energy to pump the gas out of the gas bag could be acquired in many places without using fuel: First, insert turbines between the storage tanks and the gas bags; as the bags inflate, they give energy (I know, not enough) that could be stored and used to compress the gas later. This does not affect the buoancy characteristics of the gas in the slightest. Second, the design calls for wind turbines to provide power as the aircraft moves. Third, the temperature differential between the ground and at altitude could be used to change the state of a compound like freon (you've seen those drinking birds?) and that's before we even start talking about external sources like the sun. Even if it did require fossil fuels to pump the hydrogen, this is nowhere near the fuel required to move a traditional airfram the same distance. This is a radical, yet very practical idea, but I feel it would require an unconventional airframe, similar to NASA's lifting bodies. This thing will have to be a deformed dirigible, not a wing on pontoons, to provide the volume needed to lift it. In it's final configuration, it will be bulbous and round

I believe they invented the Glider decades ago. This is simply a version of that concept.

The energy comes from wind turbines which power pneumatic motors. In this sense the "fuel" is the wind. One could also add solar panels to provide even more "fuel". It is an extremely practical idea, and the idea comes from nature. No special mathemathics are necessary. Dolphins, Whales, and other mammals which live in the sea use this concept to travel much further than they would if they were simply swimming using the kinetic energy from their food. Do some research before you post you make yourselves sound stupid.

Let's say we have a sphere massing 0.1g, filled with vacuum, and capable of varying its radius from 1cm to 5cm with 100% efficient use/extraction of compression work. This is an idealized version of the Hunt aircraft - I doubt they can build one with 100% efficiency.

Start at sea level, 4.2 mL volume
Expand by 5.2E-4 m^3
-- consume (5.2E-4 m3)*(1.0E+5 Pa) = 52 J
Rise 100m
-- external pressure drops 1280 Pa = 1.28%
-- produce 100m * 580mg * 9.81m/s^2 = 0.569 J by positive buoyancy
Contract by 5.2E-4 m^3
-- produce (52 J)*(98.72%) = 51.33 J
Drop 100m
-- produce 100m * 95mg * 9.81m/s^2 = 0.093 J by negative buoyancy
End at sea level, 4.2 mL volume (same as start condition)

Cycle net: -52 +0.569 +51.33 +0.093 = -0.008 J

Since the expansion occurs at a higher pressure than the compression, additional energy is needed which cancels out the energy gained from buoyancy. The net energy should have been 0, but since the discrepancy is

well under 1% of the cyclic storage, close enough - I did round some of the numbers.

Please note that I made no reference to the Carnot efficiency, as this is not a heat engine. Note also that the math does not depend on working fluids: under water, the buoyancy and pressure differential would be much higher, but the cycle energy would still cancel.

Regarding marine mammals' gliding, the most prominent article (on Google) is Williams et al 2000, "Sink or Swim: Strategies for Cost-Efficient Diving by Marine Mammals" which quotes apparent energy ratios of 90% to 40% on deep dives - is this what Hunt calls "a mere fraction"? Additionally the mammals studied glide down on deep dives, but cannot glide back up - they cannot voluntarally increase their buoyancy. The data are not relevent to the Hunt method which relies on active changes in buoyancy.

Of course, there might be a much more relevent study out there: perhaps whoever said "Do some research before you post you make yourselves sound stupid." will provide a reference.

The concept behind this plane is best demonstrated by an analysis of the weather,

Consider the following scenario, heat energy from the sun causes a water molecule to become vapor, vapor rises until it reaches a point where high pressure and/or low temperature cause it to condense and become liquid. The amount of energy it requires to become vapor is the same regardless of how high it goes before it condenses again, and that heat energy is returned to the atmosphere when the water condenses. Therefore the water molecule achieves potential energy equal to its height at the point of condensation. Rain falls and flows down a mountain where a dam turns the kinetic energy into electricity. This is how Gravity produces useful work for our purposes, there are other effects on the atmosphere from this process which also contribute to wind energy but I won't go into those, suffice it to say that this is a proof that gravity can in fact perform useful work if a number of conditions are met, one must have a lifting medium, some type of molecule that which has a lower density than the lifting medium when it is in the gas phase, some energy to achieve phase change, and a temperature or pressure differential to cause condensation in the upper atmosphere. Such conditions are met nicely on earth, the lifting medium is air, the molecule that has a lower density than air in the gas phase is water, the energy to achieve that phase change is conveniently provided by the sun, the temperature in the upper atmosphere is low enough to cause condensation, and voila we can get useful energy from the force of gravity.

This gravity plane is basically a different way of obtaining useful energy from the force of gravity, which as shown above is possible given the right conditions. Essentially the lifting fluid remains the same, but imagine the molecule is the plane, it uses the suns energy in the form of wind to make itself lighter than air, it rises until it gets really high like maybe 10km, then it uses some of the energy it stored up on the ground to take in cold air from the upper atmosphere, this causes it to become lighter than air, it then flies like a glide while gathering kinetic energy from its wind turbines, then when it is down near the ground provided it went high enough it will have enough energy to repeat the process

Essentially this is an engineering challenge requiring extremely light and strong materials (carbon fiber or kevlar bonded with epoxy resin), extremely efficient method of storing kinetic energy (20% efficient vertical axis wind turbines connected to air compressors), extremely large volume to minimize surface area to volume ratio to reduce weight (surface area increases by the square, volume increases by the cube, so larger = better ratio = greater lift), the latest computer hardware and software for flight control system, aerodynamic design capable of changing the aspect ratio of the wings, etcetera

It is not impossible just really hard, just as it was to design jet airplanes and other such technological marvels it requires a lot of engineers like me working long hours hammering out the details.

please note In my second paragraph I meant to say that the intake of cold air from the atmosphere causes it to be heavier than air

It's wonderful to discover that there's still a market for perpetual motion machines.