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News announcements and other topics => News => Topic started by: markdansie on December 26, 2014, 05:31:05 AM

Title: gravity powered aircraft
Post by: markdansie on December 26, 2014, 05:31:05 AM
An oldie but a goodie
http://revolution-green.com/gravity-powered-aircraft/

Title: Re: gravity powered aircraft
Post by: TinselKoala on December 26, 2014, 09:22:04 AM
Quote from: markdansie on December 26, 2014, 05:31:05 AM
An oldie but a goodie
http://revolution-green.com/gravity-powered-aircraft/ (http://revolution-green.com/gravity-powered-aircraft/)

That's hilarious all right. By the way, TedX is not Ted. The linked video talk is a TedX-Austin event, not a TED Talk.

http://tedxyouthfranklin.com/about/ted-vs-tedx

For the heavier-than-air glider to become lighter than air, by the phase change of the fluid, it must swell up somewhere so that it displaces more air than it did before. To see just how much it would have to swell up to become sufficiently buoyant to lift itself... see the Goodyear Blimp.  Good luck transforming between a buoyant lighter than air craft, and a glider with heavy wing loading powered by gravity.

I no longer fly, but for many years I gave flight instruction in high-performance sailplanes, performed the occasional airshow aerobatic sailplane demonstration, and owned a Cessna A188A ag-wagon converted to glider towing service. I used that airplane to tow many gliders during the 1991 World Soaring Championships in Uvalde TX each day of the competition. I never got a blimp rating on my licence, though.
Title: Re: gravity powered aircraft
Post by: MarkE on December 26, 2014, 10:34:43 AM
Quote from: TinselKoala on December 26, 2014, 09:22:04 AM
That's hilarious all right. By the way, TedX is not Ted. The linked video talk is a TedX-Austin event, not a TED Talk.

http://tedxyouthfranklin.com/about/ted-vs-tedx

For the heavier-than-air glider to become lighter than air, by the phase change of the fluid, it must swell up somewhere so that it displaces more air than it did before. To see just how much it would have to swell up to become sufficiently buoyant to lift itself... see the Goodyear Blimp.  Good luck transforming between a buoyant lighter than air craft, and a glider with heavy wing loading powered by gravity.

I no longer fly, but for many years I gave flight instruction in high-performance sailplanes, performed the occasional airshow aerobatic sailplane demonstration, and owned a Cessna A188A ag-wagon converted to glider towing service. I used that airplane to tow many gliders during the 1991 World Soaring Championships in Uvalde TX each day of the competition. I never got a blimp rating on my licence, though.
I cannot see how he can possibly make the numbers work either.  The aircraft is shown landing on water probably because he is envisioning something that is extremely large.  LTA craft do not fare well in winds and storms. 

I give the guy full credit for his creativity.
Title: Re: gravity powered aircraft
Post by: mscoffman on December 26, 2014, 11:03:23 AM
One of my favorite concepts would be to use a thermal coaxial balute with hydrogen in an outer envelope and air
in an inner envelope to create a balloon that could change altitude. By inflating a darker inner envelope it would
allow the balloon to absorb solar energy and ascend like a conventional thermal balloon. One could either
burn hydrogen to recover energy or compress it to a tank then electrolyze water with solar cells. Finally it uses
hydrogen buoyant gas so one could augment it's hydrogen stores by collecting water from humidity at low
altitude then electrolyze it to make up for hydrogen leakage. With all the parameters to adjust one could
keep the device flying for quite some time. Weather predicting software would be a requirement but could keep
the vehicle away from risky areas.

:S:MarkSCoffman
Title: Re: gravity powered aircraft
Post by: Pirate88179 on December 27, 2014, 05:49:02 AM
It would be much easier to take a lawn chair, and about 8 large balloons and fill them with helium and...

Wait, that has been done already.

Bill

PS  Using a BB gun for altitude control is pure genius.  Well...sort of.