10 ms·

The Tethered Uni-Rotor Network: Eternal Flight UAV

119 points by bennylope 8y ago

reaperducer 8y ago
Perhaps I just didn't understand the web page, but this seems unnecessarily complicated. 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." https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System
- grahn 8y ago
  It's not tethered to the ground. It's a group of rotating "wings" tethered to each other in the centre, wherein the centrifugal force of the rotation give structural stability. That way they get away with using less structural material, which means more of the weight can be batteries or fuel.
- deleted 8y ago
  [deleted]
- adrianmonk 8y ago
  It probably wasn't a good choice for them to use the word "tethered" in the name. It might not be incorrect, but tethered means you are connected to something. In this case, that something is the aircraft itself. Self is not the first thing most people are going to think of when they hear the word tethered. Especially since, as you point out, there are already aircraft that are tethered to the ground.
- rtkwe 8y ago
  These plan to operate much higher at 60k feet and won't be tethered to the ground. The additional height will give them better coverage than the radar aerostats you mention. I think removing the tether might be required for them to be used a lot because the tether seems like it'd a) weigh a lot requiring much larger stats and b) if they're dense enough the tethers could pose a danger to air traffic (at the very least you'd have to route planes to avoid them). Both of those get worse as the stat operates higher and the forces on the cable get higher. It may become an issue where the increased strength required increases the cable weight beyond the point where an cabled aerostat becomes viable.
mLuby 8y ago
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.
- gfodor 8y ago
  it'll be really interesting to see how this performs in extreme weather. i wonder if the cables would result in a much higher tolerance for shear, etc.
  - nradov 8y ago
    There's not much weather up at the planned operating altitude.
opless 8y ago
Is this "solar freaking roadways", but for UAVs ?
- usrusr 8y ago
  I don't think that building (maybe) better solar glider UAVs falls in that category. They basically combine the existing principles of control-surface based helicopter blade pitch control (e.g. Kaman K-Max) and blade tip propulsion, then drive them to the UAV-exclusive extreme where the individual blades gain complexity until they are a coordinated team of autonomous planes while the "body" of the helicopter along with all the complicated mechanical linkages to the blades is reduced to simple tethers between the blades and a central connection point where a stationary payload could be attached. I suspect that they are overestimating the structural savings relative to something like the helios glider (where mass was already distributed along the wing) and underestimate tether drag. The big difference is that a new type of aircraft won't fly at all if it's as bad an idea as solar roadways, whereas the latter could be built mile after mile until the world runs out of stupid money, no matter how bad it really is. If nothing else, the idea of "tethered uni-rotors" deserves a place in the canon of cool sci-to technologies that could theoretically work. They would fit in quite nicely in the future segment of Seveneves for example.
yathern 8y ago
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. 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. 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. 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.
- Mtinie 8y ago
  Regarding your second point: https://www.airbus.com/defence/uav/zephyr.html https://www.airbus.com/defence/uav/zephyr.html "The first unmanned aircraft of its kind to fly in the stratosphere, Zephyr harnesses the sun's rays, running exclusively on solar power, above the weather and conventional air traffic. It is a HAPS: a High Altitude Pseudo Satellite, able to fly for months at a time, combining the persistence of a satellite with the flexibility of a UAV." This isn't a new idea, at all. You have to go back to the late 1780's to find a time before the use of balloons as recon platforms: https://en.wikipedia.org/wiki/History_of_military_ballooning https://en.wikipedia.org/wiki/History_of_military_ballooning
  - daveFNbuck 8y ago
    You'd have to go back before humans to find a time before facial recognition was used to track individuals, yet people get upset about when facial recognition is used to automatically track and record all of your movements through ubiquitous cameras. There's a big difference between a person going up in a balloons for a few hour to scout a military locations and a swarm of drones constantly monitoring a city in peacetime.
upofadown 8y ago
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? 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? Added2: This scheme still has the problem that the downwash from each wing will affect the other wings, just like in the helicopter case.
- Pfhreak 8y ago
  The wing generates lift, the engines on the edge of the wing generate thrust. That thrust is at a tangent to the circle the wings travel. Essentially the wings are pushed forward but cabled at the side.
- unklefolk 8y ago
  Seems that the four wings rotate around the central unit creating centrifugal force that will keep the cables tight.
  - samstave 8y ago
    Wouldnt a single wing being buffetted by a downdraft or sudden turbulence cause catastrophic loss of tension between all wing tethers and the whole thing collapse? What if instead of teathers, you just had two large circles of composit, as a hub and a rim, that were stiff enough to keep all wing positions but stiffer than a flimsy string - and thus keeping formation?
    - joemi 8y ago
      I didn't watch the video (or read most of the page!) so it's possible I'm missing something, but the images show the wings having a propeller at each end, so I don't think a loss of cable tension would be catastrophic (at least not in the same way it would be if there was only one propeller per wing). The wing would presumably keep flying straight until the cable was tense again and it all started rotating again. Seems fairly self-correcting, with the second propeller.
crowbahr 8y ago
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? 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? Overall a very cool idea though!
- mikepurvis 8y ago
  The use-cases discussed in TFA all seem pretty low-power, mostly recon-type stuff. That said, it'd be interesting to contemplate what the right proportions would be to actually run a hungrier payload. At a certain point, "perpetual" also starts to run into problems of mechanical failure. Then again, if these things are cheap enough and/or able to limp home in the case of a snapped cable or failed prop motor, maybe it still works out.
  - crowbahr 8y ago
    Seems like the video talked about wanting to make it into an internet communication network, which just doesn't seam feasible to me. Then again, I'm just a programmer. I recognize I have no grasp of the power requirements for that kind of project. The inexpensive nature of them seems a major draw. I wonder if they can detach cables and have the wings fly home on their own while having the center parachute down?
  - usrusr 8y ago
    Limping home would be the easy part. It would be really impressive if the system had the ability to attach the tether of a replacement "blade" in flight, extending/replenishing the formation on the go. But we are hardly able to keep conventional solar glider UAVs in the air, I suspect that adding the drag of a tether moves the goalposts far out of reach.
sargun 8y ago
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? 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? Can anyone here call out whether or not this looks like a viable thing?
- pohl 8y ago
  They're only at the beginning of development, and they're starting at a small scale, so it's not clear whether the smaller scale drones can't achieve perpetual flight or whether that was simply not a necessary goal at this point to monetize the idea and get their business off the ground. But, assuming that there's some point as you scale down at which perpetual flight becomes impossible, my first guess would be the surface area for solar cells at being a limiting factor.
  - jselfridge 8y ago
    You're right about the surface area. Altitude is the limiting factor. In the stratosphere, the air is thin enough to warrant large wings, which have lots of area for solar cells. I attempted to design a system for the Air Force at 10-15k feet, but the wings are just to small to collect any meaningful solar energy. That's why we shifted to an internal combustion engine design for that mission. You're also right about monitizing the business. The smallest scale system is a necessary prototyping step towards eternal flight, but it also offers a compelling competitive advantage over conventional fixed-wing drones. VTOL plus 5x the flight endurance?... who wouldn't want that.
    - dharma1 8y ago
      What size would the smaller versions competing with current fixed-wing drones be? You should post this to https://www.rcgroups.com/vtols-360/ https://www.rcgroups.com/vtols-360/
sargun 8y ago
What's the current longest endurance, COTS (commercial off the shelf) flight platform?
- curtis 8y ago
  It's not at all COTS, but the Rutan Voyager [1] spent 9 days in the air on it's round-the-world flight. [1] https://en.wikipedia.org/wiki/Rutan_Voyager https://en.wikipedia.org/wiki/Rutan_Voyager
  - digikata 8y ago
    Similarly not-COTS, but a series of UAVs, a Zephyr "7" made a record 336 hour flight - 14 days, with an unofficial runs of three minutes (!!) short of 26 days aloft for a recent Zephyr S. https://en.wikipedia.org/wiki/Airbus_Zephyr https://en.wikipedia.org/wiki/Airbus_Zephyr
    - curtis 8y ago
      The Zephyr is using Lithium-Sulfur batteries, which have a better energy-to-weight ratio ("Currently the best Li–S batteries offer specific energies on the order of 500 W·h/kg" according to Wikipedia [1]). These aren't commercially available though. Twice the performance of currently available automotive batteries is a major advantage for aircraft applications. Pretty cool. [1] https://en.wikipedia.org/wiki/Lithium%E2%80%93sulfur_battery https://en.wikipedia.org/wiki/Lithium%E2%80%93sulfur_battery
gpm 8y ago
This seems like a really cool idea. What I can't figure out is the bootstrap process. How do you launch/start the wings rotating?
- RandallBrown 8y ago
  There's an image. https://static1.squarespace.com/static/5901f9f12994ca40051ae59d/t/590346c9f5e2316bee3d0122/1493387276592/TURN.jpeg?format=2500w https://static1.squarespace.com/static/5901f9f12994ca40051ae... Basically, the whole thing takes off like a helicopter, before turning the wings on their sides.
JackFr 8y ago
Balloons?
everyone 8y ago
Why not use a balloon? or dirigible or something like that?
vpribish 8y ago
clever design, but that video was awful. It came across as either ill-informed or misleading - and the beige - oh my, the beige.
- jselfridge 8y ago
  Sorry about that. It's all I had to work with. The TURN concept recently won a local business pitch competition, with a video posted on their website. Slightly (just slightly) better production quality. https://757pitch.org https://757pitch.org
jselfridge 8y ago
I'm the originator of the TURN concept, and owner of the company. I can answer any questions you guys have about the vehicle.
- fit2rule 8y ago
  Does it scale down? Could I use RC-scale technology, build my own, and use it to provide services to my own local network? Sure, we all have the eye on the industrial horizon here. But what would a "the streets have their own uses for things" application of the TURN concept look like? For instance, I build RC planes for fun, and am a huge fan of Kline-Fogleman airfoils, for their simplicity if not economy .. and I can imagine a low-cost TURN implementation based on KF airfoils which might be more viable at the LoRa/WAN levels of scale. Something easily deployable, cheap/disposable/replaceable, on a much smaller scale of industry - yet widely available.
  - Ruthalas 8y ago
    The video on the linked website mentions that smaller scales are potentially useful but implies they are not capable of indefinite flight. (It mentions a unit with a five pound payload flying for around four hours, comparing it to a conventional platform with a similar on-board battery which was able to remain aloft for around an hour.)
- andrewflnr 8y ago
  How does it take off?
- plutonorm 8y ago
  Can you generate lift from the tether. Maybe using the magnus effect?
- CarVac 8y ago
  How would it respond to gusts? How strictly does it need to maintain angular velocity as it goes around? What would the maximum speed in still air be? Some fraction of the rotor tip speed? Does the tilt-wing configuration (presumably for landing and perhaps takeoff) set the constraint on payload mass fraction, as that will require more structure than the tension-stabilized rotary mode? Or is the payload mass fraction relatively insignificant compared to the battery and solar cell mass? Safety: is there a way for it to gracefully fail? Transition from 4 blades to 3, and let the failed one dangle down as you descend? Would this be even remotely possible?
gene-h 8y ago
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]. [0]https://www.nasa.gov/feature/flight-demonstration-of-novel-atmospheric-satellite-concept https://www.nasa.gov/feature/flight-demonstration-of-novel-a... [1]https://www.nasa.gov/sites/default/files/atoms/files/14-2015_phase_i_william_englom_virtual_flight_demostration_stratospheric_dual_aircraft_platform.pdf https://www.nasa.gov/sites/default/files/atoms/files/14-2015... [2]https://arc.aiaa.org/doi/10.2514/6.2018-1492 https://arc.aiaa.org/doi/10.2514/6.2018-1492
goda90 8y ago
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.
- jselfridge 8y ago
  DARPA already looked at that through ISIS. The problem is the massive volume of gas within the airship. Even the lightest winds require a substantial amount of power to travel or station-keep. Google is using weather balloons, but they don't have any active controls, so they drift aimlessly away from the equator, and then need to be manually picked up after about a month.
carapace 8y ago
Er, use the Magnus effect. (Cf. "Magenn Power, Inc." company, now apparently defunct.) https://en.wikipedia.org/wiki/Magnus_effect https://en.wikipedia.org/wiki/Magnus_effect 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...
- plutonorm 8y ago
  Lol I just asked the same question without seeing your response. I was thinking hollow canvas tubes radiating out from a central hub, slowly unspooled in flight. Some mechanism would use the mechanism of rotation to draw air outward along the tubes to keep them inflated, combined with rotation induced from the central hub. No idea if that would work...
  - carapace 8y ago
    Sorry for the delay. I don't know if that would work either, but it sounds good. ;-) Check out "Tensairity" https://en.wikipedia.org/wiki/Tensairity https://en.wikipedia.org/wiki/Tensairity
zackmorris 8y ago
I think there is merit for the last idea in the article - some kind tethered drone array as a windmill using something like autorotation: https://en.wikipedia.org/wiki/Autorotation https://en.wikipedia.org/wiki/Autorotation Similar ideas have been suggested using balloons: http://latesttechnology-world.blogspot.com/2013/07/magenn-air-rotor-system-mars_18.html http://latesttechnology-world.blogspot.com/2013/07/magenn-ai... https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=134023 https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=134023 https://en.wikipedia.org/wiki/Airborne_wind_turbine https://en.wikipedia.org/wiki/Airborne_wind_turbine 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.
- bennylope 8y ago
  Not really sure how those ideas are all that similar to the TURN here. Those are long flying and involve tethering, but the flight systems are quite different and they're tethered to the ground.
mrlaserOO 8y ago
Energy efficient hover is fine, but the wind is going to blow it away. Especially at 65k ft! So what’s the expected forward speed it can achieve?
peter_d_sherman 8y ago
Utterly Brilliant! 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!

119 points by bennylope 8y ago

Perhaps I just didn't understand the web page, but this seems unnecessarily complicated. 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." https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System

grahn 8y ago
It's not tethered to the ground. It's a group of rotating "wings" tethered to each other in the centre, wherein the centrifugal force of the rotation give structural stability. That way they get away with using less structural material, which means more of the weight can be batteries or fuel.
deleted 8y ago
[deleted]
adrianmonk 8y ago
It probably wasn't a good choice for them to use the word "tethered" in the name. It might not be incorrect, but tethered means you are connected to something. In this case, that something is the aircraft itself. Self is not the first thing most people are going to think of when they hear the word tethered. Especially since, as you point out, there are already aircraft that are tethered to the ground.
rtkwe 8y ago
These plan to operate much higher at 60k feet and won't be tethered to the ground. The additional height will give them better coverage than the radar aerostats you mention. I think removing the tether might be required for them to be used a lot because the tether seems like it'd a) weigh a lot requiring much larger stats and b) if they're dense enough the tethers could pose a danger to air traffic (at the very least you'd have to route planes to avoid them). Both of those get worse as the stat operates higher and the forces on the cable get higher. It may become an issue where the increased strength required increases the cable weight beyond the point where an cabled aerostat becomes viable.

mLuby 8y ago

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.

gfodor 8y ago
it'll be really interesting to see how this performs in extreme weather. i wonder if the cables would result in a much higher tolerance for shear, etc.
- nradov 8y ago
  There's not much weather up at the planned operating altitude.

opless 8y ago

Is this "solar freaking roadways", but for UAVs ?

usrusr 8y ago
I don't think that building (maybe) better solar glider UAVs falls in that category. They basically combine the existing principles of control-surface based helicopter blade pitch control (e.g. Kaman K-Max) and blade tip propulsion, then drive them to the UAV-exclusive extreme where the individual blades gain complexity until they are a coordinated team of autonomous planes while the "body" of the helicopter along with all the complicated mechanical linkages to the blades is reduced to simple tethers between the blades and a central connection point where a stationary payload could be attached. I suspect that they are overestimating the structural savings relative to something like the helios glider (where mass was already distributed along the wing) and underestimate tether drag. The big difference is that a new type of aircraft won't fly at all if it's as bad an idea as solar roadways, whereas the latter could be built mile after mile until the world runs out of stupid money, no matter how bad it really is. If nothing else, the idea of "tethered uni-rotors" deserves a place in the canon of cool sci-to technologies that could theoretically work. They would fit in quite nicely in the future segment of Seveneves for example.

yathern 8y ago

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. 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. 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. 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.

Mtinie 8y ago
Regarding your second point: https://www.airbus.com/defence/uav/zephyr.html https://www.airbus.com/defence/uav/zephyr.html "The first unmanned aircraft of its kind to fly in the stratosphere, Zephyr harnesses the sun's rays, running exclusively on solar power, above the weather and conventional air traffic. It is a HAPS: a High Altitude Pseudo Satellite, able to fly for months at a time, combining the persistence of a satellite with the flexibility of a UAV." This isn't a new idea, at all. You have to go back to the late 1780's to find a time before the use of balloons as recon platforms: https://en.wikipedia.org/wiki/History_of_military_ballooning https://en.wikipedia.org/wiki/History_of_military_ballooning
- daveFNbuck 8y ago
  You'd have to go back before humans to find a time before facial recognition was used to track individuals, yet people get upset about when facial recognition is used to automatically track and record all of your movements through ubiquitous cameras. There's a big difference between a person going up in a balloons for a few hour to scout a military locations and a swarm of drones constantly monitoring a city in peacetime.

upofadown 8y ago

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? 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? Added2: This scheme still has the problem that the downwash from each wing will affect the other wings, just like in the helicopter case.

Pfhreak 8y ago
The wing generates lift, the engines on the edge of the wing generate thrust. That thrust is at a tangent to the circle the wings travel. Essentially the wings are pushed forward but cabled at the side.
unklefolk 8y ago
Seems that the four wings rotate around the central unit creating centrifugal force that will keep the cables tight.
- samstave 8y ago
  Wouldnt a single wing being buffetted by a downdraft or sudden turbulence cause catastrophic loss of tension between all wing tethers and the whole thing collapse? What if instead of teathers, you just had two large circles of composit, as a hub and a rim, that were stiff enough to keep all wing positions but stiffer than a flimsy string - and thus keeping formation?
  - joemi 8y ago
    I didn't watch the video (or read most of the page!) so it's possible I'm missing something, but the images show the wings having a propeller at each end, so I don't think a loss of cable tension would be catastrophic (at least not in the same way it would be if there was only one propeller per wing). The wing would presumably keep flying straight until the cable was tense again and it all started rotating again. Seems fairly self-correcting, with the second propeller.

crowbahr 8y ago

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? 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? Overall a very cool idea though!

mikepurvis 8y ago
The use-cases discussed in TFA all seem pretty low-power, mostly recon-type stuff. That said, it'd be interesting to contemplate what the right proportions would be to actually run a hungrier payload. At a certain point, "perpetual" also starts to run into problems of mechanical failure. Then again, if these things are cheap enough and/or able to limp home in the case of a snapped cable or failed prop motor, maybe it still works out.
- crowbahr 8y ago
  Seems like the video talked about wanting to make it into an internet communication network, which just doesn't seam feasible to me. Then again, I'm just a programmer. I recognize I have no grasp of the power requirements for that kind of project. The inexpensive nature of them seems a major draw. I wonder if they can detach cables and have the wings fly home on their own while having the center parachute down?
- usrusr 8y ago
  Limping home would be the easy part. It would be really impressive if the system had the ability to attach the tether of a replacement "blade" in flight, extending/replenishing the formation on the go. But we are hardly able to keep conventional solar glider UAVs in the air, I suspect that adding the drag of a tether moves the goalposts far out of reach.

sargun 8y ago

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? 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? Can anyone here call out whether or not this looks like a viable thing?

pohl 8y ago
They're only at the beginning of development, and they're starting at a small scale, so it's not clear whether the smaller scale drones can't achieve perpetual flight or whether that was simply not a necessary goal at this point to monetize the idea and get their business off the ground. But, assuming that there's some point as you scale down at which perpetual flight becomes impossible, my first guess would be the surface area for solar cells at being a limiting factor.
- jselfridge 8y ago
  You're right about the surface area. Altitude is the limiting factor. In the stratosphere, the air is thin enough to warrant large wings, which have lots of area for solar cells. I attempted to design a system for the Air Force at 10-15k feet, but the wings are just to small to collect any meaningful solar energy. That's why we shifted to an internal combustion engine design for that mission. You're also right about monitizing the business. The smallest scale system is a necessary prototyping step towards eternal flight, but it also offers a compelling competitive advantage over conventional fixed-wing drones. VTOL plus 5x the flight endurance?... who wouldn't want that.
  - dharma1 8y ago
    What size would the smaller versions competing with current fixed-wing drones be? You should post this to https://www.rcgroups.com/vtols-360/ https://www.rcgroups.com/vtols-360/

sargun 8y ago

What's the current longest endurance, COTS (commercial off the shelf) flight platform?

curtis 8y ago
It's not at all COTS, but the Rutan Voyager [1] spent 9 days in the air on it's round-the-world flight. [1] https://en.wikipedia.org/wiki/Rutan_Voyager https://en.wikipedia.org/wiki/Rutan_Voyager
- digikata 8y ago
  Similarly not-COTS, but a series of UAVs, a Zephyr "7" made a record 336 hour flight - 14 days, with an unofficial runs of three minutes (!!) short of 26 days aloft for a recent Zephyr S. https://en.wikipedia.org/wiki/Airbus_Zephyr https://en.wikipedia.org/wiki/Airbus_Zephyr
  - curtis 8y ago
    The Zephyr is using Lithium-Sulfur batteries, which have a better energy-to-weight ratio ("Currently the best Li–S batteries offer specific energies on the order of 500 W·h/kg" according to Wikipedia [1]). These aren't commercially available though. Twice the performance of currently available automotive batteries is a major advantage for aircraft applications. Pretty cool. [1] https://en.wikipedia.org/wiki/Lithium%E2%80%93sulfur_battery https://en.wikipedia.org/wiki/Lithium%E2%80%93sulfur_battery

gpm 8y ago

This seems like a really cool idea. What I can't figure out is the bootstrap process. How do you launch/start the wings rotating?

RandallBrown 8y ago
There's an image. https://static1.squarespace.com/static/5901f9f12994ca40051ae59d/t/590346c9f5e2316bee3d0122/1493387276592/TURN.jpeg?format=2500w https://static1.squarespace.com/static/5901f9f12994ca40051ae... Basically, the whole thing takes off like a helicopter, before turning the wings on their sides.

JackFr 8y ago

Balloons?

everyone 8y ago

Why not use a balloon? or dirigible or something like that?

vpribish 8y ago

clever design, but that video was awful. It came across as either ill-informed or misleading - and the beige - oh my, the beige.

jselfridge 8y ago
Sorry about that. It's all I had to work with. The TURN concept recently won a local business pitch competition, with a video posted on their website. Slightly (just slightly) better production quality. https://757pitch.org https://757pitch.org

jselfridge 8y ago

I'm the originator of the TURN concept, and owner of the company. I can answer any questions you guys have about the vehicle.

fit2rule 8y ago
Does it scale down? Could I use RC-scale technology, build my own, and use it to provide services to my own local network? Sure, we all have the eye on the industrial horizon here. But what would a "the streets have their own uses for things" application of the TURN concept look like? For instance, I build RC planes for fun, and am a huge fan of Kline-Fogleman airfoils, for their simplicity if not economy .. and I can imagine a low-cost TURN implementation based on KF airfoils which might be more viable at the LoRa/WAN levels of scale. Something easily deployable, cheap/disposable/replaceable, on a much smaller scale of industry - yet widely available.
- Ruthalas 8y ago
  The video on the linked website mentions that smaller scales are potentially useful but implies they are not capable of indefinite flight. (It mentions a unit with a five pound payload flying for around four hours, comparing it to a conventional platform with a similar on-board battery which was able to remain aloft for around an hour.)
andrewflnr 8y ago
How does it take off?
plutonorm 8y ago
Can you generate lift from the tether. Maybe using the magnus effect?
CarVac 8y ago
How would it respond to gusts? How strictly does it need to maintain angular velocity as it goes around? What would the maximum speed in still air be? Some fraction of the rotor tip speed? Does the tilt-wing configuration (presumably for landing and perhaps takeoff) set the constraint on payload mass fraction, as that will require more structure than the tension-stabilized rotary mode? Or is the payload mass fraction relatively insignificant compared to the battery and solar cell mass? Safety: is there a way for it to gracefully fail? Transition from 4 blades to 3, and let the failed one dangle down as you descend? Would this be even remotely possible?

gene-h 8y ago

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]. [0]https://www.nasa.gov/feature/flight-demonstration-of-novel-atmospheric-satellite-concept https://www.nasa.gov/feature/flight-demonstration-of-novel-a... [1]https://www.nasa.gov/sites/default/files/atoms/files/14-2015_phase_i_william_englom_virtual_flight_demostration_stratospheric_dual_aircraft_platform.pdf https://www.nasa.gov/sites/default/files/atoms/files/14-2015... [2]https://arc.aiaa.org/doi/10.2514/6.2018-1492 https://arc.aiaa.org/doi/10.2514/6.2018-1492

goda90 8y ago

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.

jselfridge 8y ago
DARPA already looked at that through ISIS. The problem is the massive volume of gas within the airship. Even the lightest winds require a substantial amount of power to travel or station-keep. Google is using weather balloons, but they don't have any active controls, so they drift aimlessly away from the equator, and then need to be manually picked up after about a month.

carapace 8y ago

Er, use the Magnus effect. (Cf. "Magenn Power, Inc." company, now apparently defunct.) https://en.wikipedia.org/wiki/Magnus_effect https://en.wikipedia.org/wiki/Magnus_effect 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...

plutonorm 8y ago
Lol I just asked the same question without seeing your response. I was thinking hollow canvas tubes radiating out from a central hub, slowly unspooled in flight. Some mechanism would use the mechanism of rotation to draw air outward along the tubes to keep them inflated, combined with rotation induced from the central hub. No idea if that would work...
- carapace 8y ago
  Sorry for the delay. I don't know if that would work either, but it sounds good. ;-) Check out "Tensairity" https://en.wikipedia.org/wiki/Tensairity https://en.wikipedia.org/wiki/Tensairity

zackmorris 8y ago

I think there is merit for the last idea in the article - some kind tethered drone array as a windmill using something like autorotation: https://en.wikipedia.org/wiki/Autorotation https://en.wikipedia.org/wiki/Autorotation Similar ideas have been suggested using balloons: http://latesttechnology-world.blogspot.com/2013/07/magenn-air-rotor-system-mars_18.html http://latesttechnology-world.blogspot.com/2013/07/magenn-ai... https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=134023 https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=134023 https://en.wikipedia.org/wiki/Airborne_wind_turbine https://en.wikipedia.org/wiki/Airborne_wind_turbine 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.

bennylope 8y ago
Not really sure how those ideas are all that similar to the TURN here. Those are long flying and involve tethering, but the flight systems are quite different and they're tethered to the ground.

mrlaserOO 8y ago

Energy efficient hover is fine, but the wind is going to blow it away. Especially at 65k ft! So what’s the expected forward speed it can achieve?

peter_d_sherman 8y ago

Utterly Brilliant! 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!