gravity plane - perpetum mobile

It's strange I can find no thread about gravity plane concept. It promises a perpetum mobile, by an innovative principle, which anyway won't work.

The principle is, that you have compressed helium and air in different tanks. When you want to lift off, you expand the helium in bigger volume (some type of balloon like zeppelins had) and you get lighter than air and you are airborne! At the same time you use compressed air to run the engines and gain speed. Than you get to the altitude where you aren't lighter than air anymore (about 10 miles) and compress helium back to get heavier. You than fly steeply back down to sea level (or ground level) and on the way by gaining speed compress air back for propulsion. The designers promise, this process could be repeated as many times needed. Of course no fuel is used for propulsion

BUT it has a big problem. It is a perpetum mobile (machine that can run without fuel (and without solar panels) for as much time as needed). Such machine does not exist and never will, because of the basic laws of physics. In this concept they forgot that for compressing helium on the top of the curve takes a lot of energy and so does the compressing of the air on the ground level (because you have to make balloon empty for helium). The point is, perpetum mobile does not and will not exist.

My question is, how come that according to this link they presented the concept on "two of the nation's largest aviation conferences - The National Business Aviation Association's (NBAA) Conference in Orlando, FL on the 7-9 of October and Aviation Week's A&D Programs & Productivity Conference in Arlington, Texas on the 28-30 of October" (don't know which year) and there is no site on the net I could find that denies the concept.

What does the ATS think? Is anything wrong with my theory??

And there is a link to youtube video presenting the concept

And the official explanation of the method:
In order for the GravityPlane to become airborne, gas bags inside a pair of rigid, zeppelin-like structures are filled with helium from storage tanks inside the vehicle. This causes the aircraft to become lighter-than-air, and it rises from the ground. Compressed-air jets on the sides of the craft add further propulsion, pushing the vehicle skyward and decreasing the craft's overall weight by releasing the stored air which acts as ballast. Once the craft reaches the altitude where the helium is no longer lighter than the surrounding air-- theoretically as high as ten miles up-- it is unable to climb any further. Some of the stored compressed air is then expanded into the dirigible areas, decreasing the buoyancy effect of the helium and starting the aircraft's descent phase.

Well, you are expending both energy and fuel - as you say, the energy required to recompress the lifting agent is non zero, and both yourself and the blurb mentions compressed air jets as assisting motors, which means fuel being expended.

So, unless there is another source of energy, the entire idea gets consigned to the box labelled 'more perpetual motion machines - wont they ever learn?'

Nuff said really.

The fact is that as you vent gas, you need to replace it. This is solved here by adding tanks of compressed air and helium. But this isn't a perpetual motion machine since those tanks are going to be used up at some point, whether you keep compressing air or not. Theoretically you could have fuel shipped to the dirigible while in transit, but that takes 1) energy to compress the gases, 2) energy to get the containers to the dirigible, and 3) that's not really perpetual motion. If it was, you take an F-15, have it refueled by a tanker every time it needed it, and call that a perpetual motion machine. And we know it isn't.

Moving on to the specs side, if it's using a balloon of any sort it's gonna be huge. It will probably have the same handling and speed characteristics as the Zeppelins you've already mentioned. I suppose you could ship large stuff with them, but even then nobody wants their package to come in 6-8 weeks via Zeppelin Express. No matter how cool that would sound.