Another interesting idea in this domain is to use wind power rather than solar power. Wind gradients can be harnessed through dynamic soaring although this can be a bit limiting. One way we might get around this is by flying two airplanes connected by a long tether.[0][1] One airplane flying at a different altitude where the wind is significantly different can be used like a kite sail to pull the other airplane. Although it has been shown to be a pretty nasty control problem at least for a human[2].<p>[0]<a href="https://www.nasa.gov/feature/flight-demonstration-of-novel-atmospheric-satellite-concept" rel="nofollow">https://www.nasa.gov/feature/flight-demonstration-of-novel-a...</a>
[1]<a href="https://www.nasa.gov/sites/default/files/atoms/files/14-2015_phase_i_william_englom_virtual_flight_demostration_stratospheric_dual_aircraft_platform.pdf" rel="nofollow">https://www.nasa.gov/sites/default/files/atoms/files/14-2015...</a>
[2]<a href="https://arc.aiaa.org/doi/10.2514/6.2018-1492" rel="nofollow">https://arc.aiaa.org/doi/10.2514/6.2018-1492</a>
Not sure I understand the images. The cables seem to be connected to the end of the wing units. A wing can't normally generate force longitudinally. So how is the wing generating cable tension?<p>Added: OK, it is all generated by the centripetal force caused by the mass of the wing units. So fast spinning and lots of cable/parasitic drag to get the wings reasonably level. Seems like a lot of wing area for a small payload. How is this better than just a wing large enough to support the payload with cables to distribute the load across the wing length?<p>Added2: This scheme still has the problem that the downwash from each wing will affect the other wings, just like in the helicopter case.
This is very interesting. I'm a little confused though. The page talks at length about eternal flight, and how the turn system is supposed to enable them. Then, in the "Smaller Scale Commercial Drone" section (which I imagine is a smaller scale version of TURN), it states that the endurance is only 4.5-7.5 hours. What does scale do, which enables eternal flight? Is it just a matter of having more power on board?<p>In addition, what are these eternal flight numbers based on in terms of latitude, and season? In the video, he states that they were looking at internal combustion @ 30 days. What about the solar approach? Would 18 hours a day of light be enough? 12? 6?<p>Can anyone here call out whether or not this looks like a viable thing?
Very exciting project! Love the idea, and can't wait to see some proof of concepts eventually. It obviously has the potential to be revolutionary in the aerospace industry, though time will tell if it's as effective as claimed of course.<p>They compare the TURN concept to satellites in the beginning, mentioning only positives by comparison - of which there are indeed many (cheaper, better comms). One thing I didn't see mentioned was the failure mode between the two. A satellite that ceases to function will stay in orbit, until this orbit decays enough for it to burns in the upper atmosphere. If one of the rotors on this device fails, it will just come crashing down to earth.<p>And also, in typical neo-luddite fashion, I'm fearful for the surveillance applications of this device. Even if staying airborne isn't eventually completely free (eternal flight) with this system, the ability to stay up for 9 hours at a time on a few Li-Ion cells opens up a world of possibilities, not all of which are great. If NOAA can afford to put a number of these out in the Atlantic to get better atmospheric readings, surely cities, states, city-states, and others can afford to put a number of these above their populace.<p>However, progress is inevitable, and the technology can't always be blamed for it's potentially negative applications. I think this is an amazing project - but it will require some self-control to not let this push us further into a surveillance state.
Perhaps I just didn't understand the web page, but this seems unnecessarily complicated.<p>The Department of Customs and Border Protection already operates a fleet of tethered airships. These seem to be a much simpler solution to "eternal flight."<p><a href="https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System" rel="nofollow">https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System</a>
I wonder if the development of thinner, flexible solar panels and batteries would make a lighter than air UAV a better choice for eternal flight. That way it only needs to power rotors for positioning instead of maintaining flight.
I have to wonder what the maximum translational velocity would be for these hovering platforms. How well could they deal with high winds? Gusts? How quickly could they change their position?<p>To make a comms network you'd need them relatively evenly spaced out to maintain coverage over a wide area. You'd also need them to have beefy and power hungry broadcast/receiver systems. How well can they scale with the solar energy?<p>Overall a very cool idea though!
I think there is merit for the last idea in the article - some kind tethered drone array as a windmill using something like autorotation:<p><a href="https://en.wikipedia.org/wiki/Autorotation" rel="nofollow">https://en.wikipedia.org/wiki/Autorotation</a><p>Similar ideas have been suggested using balloons:<p><a href="http://latesttechnology-world.blogspot.com/2013/07/magenn-air-rotor-system-mars_18.html" rel="nofollow">http://latesttechnology-world.blogspot.com/2013/07/magenn-ai...</a><p><a href="https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=134023" rel="nofollow">https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=134023</a><p><a href="https://en.wikipedia.org/wiki/Airborne_wind_turbine" rel="nofollow">https://en.wikipedia.org/wiki/Airborne_wind_turbine</a><p>An array of wind-powered drones could scale well beyond what's possible with a traditional wind turbine, since most of the torque gets applied at the wingtips. There might be advantages with inconsistent wind gusts too, since the rotor could wind up in strong wind and unwind in weak wind. Startup costs would be negligible since a few drones could start the rotor and more could be added as needed. It might even by safer for birds if a drone array turns slower than a fixed rotor.
Utterly Brilliant!<p>Something like this is sorely needed for bringing broadband to other parts of the world. Best of luck to Justin in this endeavor. I hope he succeeds wildly!
Is the cable portion essential? I'd think a semi-rigid structure (like they talk about with helicopter blades or glider wings) when under load would survive longer.
Er, use the Magnus effect. (Cf. "Magenn Power, Inc." company, now apparently defunct.)<p><a href="https://en.wikipedia.org/wiki/Magnus_effect" rel="nofollow">https://en.wikipedia.org/wiki/Magnus_effect</a><p>I've been playing with geodesic cellular kites, and "eternal" flight is certainly possible. If the ratio of surface area to mass is great enough it's actually hard to stay on the ground. Cellular kites scale. I would like to eventually make flying buildings, etc...