[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.10,0:00:14.93,Default,,0000,0000,0000,,{\i1}34C3 preroll music{\i0}
Dialogue: 0,0:00:14.93,0:00:23.14,Default,,0000,0000,0000,,Christoph Sieg: The idea is now to go from\Nspace back to earth and try to use drones
Dialogue: 0,0:00:23.14,0:00:27.96,Default,,0000,0000,0000,,– so autonomous flying vehicles – for\Npower generation. So this is the second
Dialogue: 0,0:00:27.96,0:00:33.10,Default,,0000,0000,0000,,part. So the outline here is …\N{\i1}Applause{\i0}
Dialogue: 0,0:00:33.10,0:00:41.58,Default,,0000,0000,0000,,Christoph: Thank you very much.\N{\i1}Applause{\i0}
Dialogue: 0,0:00:41.58,0:00:46.56,Default,,0000,0000,0000,,Christoph: So the outline is that first I\Nwill introduce the source here and
Dialogue: 0,0:00:46.56,0:00:52.39,Default,,0000,0000,0000,,motivate why it is a good idea to harvest\Nhigh altitude winds and produce energy
Dialogue: 0,0:00:52.39,0:00:58.02,Default,,0000,0000,0000,,from them. The technological part will\Ncome in the second part here. This is
Dialogue: 0,0:00:58.02,0:01:02.29,Default,,0000,0000,0000,,about the technology which is called\Nairborne wind energy. And in a third part
Dialogue: 0,0:01:02.29,0:01:06.63,Default,,0000,0000,0000,,I want to show how you can build a wind\Ndrone for low cost for yourself and
Dialogue: 0,0:01:06.63,0:01:12.63,Default,,0000,0000,0000,,experiment with this kind of technology.\NSo let's start with the first part. And
Dialogue: 0,0:01:12.63,0:01:18.68,Default,,0000,0000,0000,,here as a reminder is the conventional\Nenergy supplier wish list, so probably
Dialogue: 0,0:01:18.68,0:01:23.85,Default,,0000,0000,0000,,what your global players in conventional\Nenergy would think about it or tell you:
Dialogue: 0,0:01:23.85,0:01:29.38,Default,,0000,0000,0000,,They would say that is a surely clean-\Nenough resource and, meaning on timescales
Dialogue: 0,0:01:29.38,0:01:33.27,Default,,0000,0000,0000,,here, it is exploitable of the order of\None human life expectancy, it's
Dialogue: 0,0:01:33.27,0:01:37.67,Default,,0000,0000,0000,,controllable especially economically and\Npolitically, it is depreciable
Dialogue: 0,0:01:37.67,0:01:43.91,Default,,0000,0000,0000,,economically and it leads so to a very\Nhigh profit for some players.
Dialogue: 0,0:01:43.91,0:01:47.36,Default,,0000,0000,0000,,Unfortunately there's also the\Ntechnological part and here sometimes it's
Dialogue: 0,0:01:47.36,0:01:54.00,Default,,0000,0000,0000,,driven by hope, saying it will be OK. But,\Nas we know, it might be mostly harmless.
Dialogue: 0,0:01:54.00,0:01:58.91,Default,,0000,0000,0000,,So as we see here for instance there are\Ncatastrophes like Chernobyl. This is after
Dialogue: 0,0:01:58.91,0:02:03.53,Default,,0000,0000,0000,,the catastrophe where you have the\Nmemorial for the people who died. Then you
Dialogue: 0,0:02:03.53,0:02:09.73,Default,,0000,0000,0000,,have scenarios during the catastrophe\Nhere. This is Deepwater Horizon being like
Dialogue: 0,0:02:09.73,0:02:15.05,Default,,0000,0000,0000,,desperately tried to extinguish the fire\Nby the US Coast Guard and Fire Brigades.
Dialogue: 0,0:02:15.05,0:02:20.05,Default,,0000,0000,0000,,And of course – what I don't have to\Nmention here, but in times of fake news
Dialogue: 0,0:02:20.05,0:02:25.76,Default,,0000,0000,0000,,it's important to mention – we are before\Nthe catastrophe. So this is here a plot of
Dialogue: 0,0:02:25.76,0:02:31.42,Default,,0000,0000,0000,,the carbon dioxide concentration in the\Natmosphere taking from ice. And as you see
Dialogue: 0,0:02:31.42,0:02:36.75,Default,,0000,0000,0000,,here the ice ages give this variations\Nover 500,000 years, and now we are at this
Dialogue: 0,0:02:36.75,0:02:41.67,Default,,0000,0000,0000,,spot here that points up. And if you\Nresolve this into the time scale, extent
Dialogue: 0,0:02:41.67,0:02:46.31,Default,,0000,0000,0000,,this time scale from the last thousand to\N2,000 years here – so we are here at this
Dialogue: 0,0:02:46.31,0:02:51.54,Default,,0000,0000,0000,,spot at 2000, year 2000 – then you see\Nthat this rise has started at the
Dialogue: 0,0:02:51.54,0:02:55.59,Default,,0000,0000,0000,,industrialization. So it's a clear sign\Nthat we have to do something. And we have
Dialogue: 0,0:02:55.59,0:02:56.79,Default,,0000,0000,0000,,to do it quickly.
Dialogue: 0,0:02:56.79,0:03:05.62,Default,,0000,0000,0000,,{\i1}Applause{\i0}
Dialogue: 0,0:03:05.62,0:03:10.14,Default,,0000,0000,0000,,Christoph: So now let's try to propose\Nsomething which can be part of the
Dialogue: 0,0:03:10.14,0:03:15.57,Default,,0000,0000,0000,,solution, namely sustainable energies. And\Nhere's a wish list of what probably you
Dialogue: 0,0:03:15.57,0:03:19.59,Default,,0000,0000,0000,,would think it should be: It should be\Nsustainable, ubiquitous, continous,
Dialogue: 0,0:03:19.59,0:03:24.27,Default,,0000,0000,0000,,accessible and profitable at the very end.\NSo does such a source exist? And first I
Dialogue: 0,0:03:24.27,0:03:28.13,Default,,0000,0000,0000,,should define what it means. So\Nsustainable means it should serve present
Dialogue: 0,0:03:28.13,0:03:31.94,Default,,0000,0000,0000,,needs without compromising the future –\Nand this is clearly not what we are doing
Dialogue: 0,0:03:31.94,0:03:38.47,Default,,0000,0000,0000,,now – so it should be available on\Ntimescales which are like the lifetime of
Dialogue: 0,0:03:38.47,0:03:43.15,Default,,0000,0000,0000,,our central star if possible. It should be\Nubiquitous, meaning that it should be
Dialogue: 0,0:03:43.15,0:03:48.78,Default,,0000,0000,0000,,present almost on any location on earth so\Nthat we can without a very complicated
Dialogue: 0,0:03:48.78,0:03:54.29,Default,,0000,0000,0000,,long-range infrastructure have access to\Nthe energy. It should be continuous,
Dialogue: 0,0:03:54.29,0:03:58.72,Default,,0000,0000,0000,,meaning it should be present at almost any\Nday time and seasons, so that we can plan
Dialogue: 0,0:03:58.72,0:04:02.68,Default,,0000,0000,0000,,of what we produce. And of course it\Nshould be accessible, meaning it can be
Dialogue: 0,0:04:02.68,0:04:08.53,Default,,0000,0000,0000,,tapped by the technology and lead to a\Nsignificant contribution to our energy
Dialogue: 0,0:04:08.53,0:04:14.53,Default,,0000,0000,0000,,mix. And profitable should of course also\Nbe. So does it exist? And the answer is
Dialogue: 0,0:04:14.53,0:04:20.62,Default,,0000,0000,0000,,yes and I want to show that this airborne\Nwind energy can be a big part of it. So
Dialogue: 0,0:04:20.62,0:04:27.54,Default,,0000,0000,0000,,here I have a table of some sustainable\Nenergy sources and the wishlist items are
Dialogue: 0,0:04:27.54,0:04:33.13,Default,,0000,0000,0000,,written here and I put some of the\Nsustainable sources. So there is fusion,
Dialogue: 0,0:04:33.13,0:04:38.05,Default,,0000,0000,0000,,there is solar energy – terrestrial and\Nalso the spacial energy which was
Dialogue: 0,0:04:38.05,0:04:42.82,Default,,0000,0000,0000,,presented by Anja and by Stefan before –\Nhydro energy, geothermal energy and
Dialogue: 0,0:04:42.82,0:04:47.18,Default,,0000,0000,0000,,conventional wind energy; where by\Nconventional wind energy I mean wind
Dialogue: 0,0:04:47.18,0:04:53.72,Default,,0000,0000,0000,,energy up to approximately 100 meter which\Nis the hub height of wind turbines,
Dialogue: 0,0:04:53.72,0:05:00.29,Default,,0000,0000,0000,,approximately. And as you can see some of\Nthese items here are not fulfilled by all
Dialogue: 0,0:05:00.29,0:05:08.31,Default,,0000,0000,0000,,these different approaches. So for example\Nthe spacial energy is clearly not
Dialogue: 0,0:05:08.31,0:05:13.84,Default,,0000,0000,0000,,ubiquitous, because you have this beam as\Nwe heard which is just like basically
Dialogue: 0,0:05:13.84,0:05:17.68,Default,,0000,0000,0000,,hitting a certain spot on the earth and\Nthere are transferred into energy, so you
Dialogue: 0,0:05:17.68,0:05:23.18,Default,,0000,0000,0000,,have to distribute this energy. Also it is\Nnot yet accessible. On the other hand wind
Dialogue: 0,0:05:23.18,0:05:27.27,Default,,0000,0000,0000,,energy – here conventional wind energy –\Nis not ubiquitous, because you can only
Dialogue: 0,0:05:27.27,0:05:32.21,Default,,0000,0000,0000,,select certain spots. And it is not\Ncontinuous, because you cannot really plan
Dialogue: 0,0:05:32.21,0:05:37.75,Default,,0000,0000,0000,,when the wind is blowing and when it's not\Nblowing. So let's add to this list what is
Dialogue: 0,0:05:37.75,0:05:42.18,Default,,0000,0000,0000,,called high altitude wind. And high\Naltitude wind is clearly sustainable,
Dialogue: 0,0:05:42.18,0:05:46.73,Default,,0000,0000,0000,,because it's also wind energy – so it's\Nlike driven as all the other wind energy
Dialogue: 0,0:05:46.73,0:05:53.68,Default,,0000,0000,0000,,as well. And high altitude here means to\Ngo to heights which are above 200 meters
Dialogue: 0,0:05:53.68,0:06:04.57,Default,,0000,0000,0000,,and try to drain energy from these winds.\NSo let me argue why it is a ubiquitous
Dialogue: 0,0:06:04.57,0:06:10.25,Default,,0000,0000,0000,,source. And for this Philip who is also\Nhere and part of the team – I'm very happy
Dialogue: 0,0:06:10.25,0:06:15.09,Default,,0000,0000,0000,,he has made this very nice plot here which\Nshows the western part of Europe and it
Dialogue: 0,0:06:15.09,0:06:20.80,Default,,0000,0000,0000,,shows the ratio of wind power which you\Ncan extract at an optimal height which
Dialogue: 0,0:06:20.80,0:06:24.99,Default,,0000,0000,0000,,should be below 1,000 meter – so this is\Njust an arbitrary at the moment limit – to
Dialogue: 0,0:06:24.99,0:06:31.10,Default,,0000,0000,0000,,say that we can have a system which can\Nbasically get up to thousand meter height
Dialogue: 0,0:06:31.10,0:06:38.31,Default,,0000,0000,0000,,and compare it to the wind energy which is\Nbasically available at hundred meter. And
Dialogue: 0,0:06:38.31,0:06:43.28,Default,,0000,0000,0000,,in this plot you can see at the coastline\Nthere is a line here and this line is the
Dialogue: 0,0:06:43.28,0:06:48.31,Default,,0000,0000,0000,,line where in the interior you have\Nalready a doubling of the wind power. So
Dialogue: 0,0:06:48.31,0:06:53.20,Default,,0000,0000,0000,,meaning at the coast line itself if you go\Nto higher altitude you have the double
Dialogue: 0,0:06:53.20,0:06:58.10,Default,,0000,0000,0000,,wind power available then at hundred\Nmeter. Even better, directly at the coast
Dialogue: 0,0:06:58.10,0:07:01.88,Default,,0000,0000,0000,,line there is another line which is a\Nfactor of four better. So as soon as you
Dialogue: 0,0:07:01.88,0:07:07.99,Default,,0000,0000,0000,,put your wind turbines on land side, you\Nwill be a factor of, you have access to a
Dialogue: 0,0:07:07.99,0:07:12.49,Default,,0000,0000,0000,,factor of four higher wind power. And\Nhere, in the region slightly south of
Dialogue: 0,0:07:12.49,0:07:17.59,Default,,0000,0000,0000,,Leipzig, there's another line, this is a\Nfactor of eight where you become better in
Dialogue: 0,0:07:17.59,0:07:23.78,Default,,0000,0000,0000,,wind power, in high altitudes wind power.\NSo, seeing that the coastal regions have
Dialogue: 0,0:07:23.78,0:07:27.68,Default,,0000,0000,0000,,already a factor of four in this ratio\Nbetter and the inland between four and
Dialogue: 0,0:07:27.68,0:07:33.32,Default,,0000,0000,0000,,eight. Oh, the wrong sign. Sorry, they\Nshould be reversed of course. So, saying
Dialogue: 0,0:07:33.32,0:07:39.90,Default,,0000,0000,0000,,that here the site of conventional wind-\Nenergy harvesting, which are now very
Dialogue: 0,0:07:39.90,0:07:44.09,Default,,0000,0000,0000,,limited, and where you put for instance\Nall the wind turbines in the north, they
Dialogue: 0,0:07:44.09,0:07:47.41,Default,,0000,0000,0000,,become much more accessible if you go to\Nhigher heights. Because there you can
Dialogue: 0,0:07:47.41,0:07:53.39,Default,,0000,0000,0000,,basically use all the land sites. So this\Nis where you have more sites available
Dialogue: 0,0:07:53.39,0:08:00.48,Default,,0000,0000,0000,,when you harvest at optimal height. And\Nhere, as an example about why it is a
Dialogue: 0,0:08:00.48,0:08:06.08,Default,,0000,0000,0000,,continuous source, you see a time\Ndistribution of the wind velocity in
Dialogue: 0,0:08:06.08,0:08:15.21,Default,,0000,0000,0000,,January 2016 in Leipzig. The wind velocity\Nis here increasing from yellow to red, and
Dialogue: 0,0:08:15.21,0:08:19.73,Default,,0000,0000,0000,,the altitude is displayed here, and this\Nis the time scale of the month. And what
Dialogue: 0,0:08:19.73,0:08:24.23,Default,,0000,0000,0000,,you can see is, at hundred meter height\Nyou have almost like only in the lower
Dialogue: 0,0:08:24.23,0:08:27.77,Default,,0000,0000,0000,,parts you have winds, whereas, if you go\Nto higher heights you have the reddish
Dialogue: 0,0:08:27.77,0:08:33.02,Default,,0000,0000,0000,,parts where you have high wind velocities.\NSo this shows that continuity is already
Dialogue: 0,0:08:33.02,0:08:38.07,Default,,0000,0000,0000,,improved if you go to higher altitude,\Nespecially for land sites. And this is
Dialogue: 0,0:08:38.07,0:08:42.46,Default,,0000,0000,0000,,almost impossible for conventional wind\Nturbines. You would have to build a mast
Dialogue: 0,0:08:42.46,0:08:48.96,Default,,0000,0000,0000,,higher and much, much bigger structures.\NAnd also, what is displayed here is the
Dialogue: 0,0:08:48.96,0:08:53.16,Default,,0000,0000,0000,,optimal harvesting height. So this is the\Nheight, again below thousand meter, where
Dialogue: 0,0:08:53.16,0:08:59.72,Default,,0000,0000,0000,,it would be optimal to harvest wind at a\Ncertain time, displayed over the whole
Dialogue: 0,0:08:59.72,0:09:07.39,Default,,0000,0000,0000,,month. And if one goes from this plot to\Nthe histograms, so to the time
Dialogue: 0,0:09:07.39,0:09:11.51,Default,,0000,0000,0000,,distribution of the different wind\Nvelocities, you get this picture here. So
Dialogue: 0,0:09:11.51,0:09:16.71,Default,,0000,0000,0000,,this are the spots the histograms of 100,\N170, 500, 1000 meter, and of the optimal
Dialogue: 0,0:09:16.71,0:09:20.79,Default,,0000,0000,0000,,height, so if you adjust your height. And\None of the things that you can see is that
Dialogue: 0,0:09:20.79,0:09:26.60,Default,,0000,0000,0000,,the mean is clearly shifted to higher wind\Nvelocities if you increase the height. And
Dialogue: 0,0:09:26.60,0:09:31.77,Default,,0000,0000,0000,,also, if you harvest at optimal altitude\Nyou shift the whole probability
Dialogue: 0,0:09:31.77,0:09:36.87,Default,,0000,0000,0000,,distribution to the right. So and what\Nincreases there is that the fraction of
Dialogue: 0,0:09:36.87,0:09:43.43,Default,,0000,0000,0000,,time below five meter per second, which is\Nlike the the time where the cut in wind
Dialogue: 0,0:09:43.43,0:09:47.47,Default,,0000,0000,0000,,speed for a wind turbine, so you would\Nlike starting produce energy, the
Dialogue: 0,0:09:47.47,0:09:53.28,Default,,0000,0000,0000,,probability to have such winds is\Nincreased from 76% to 87%, which is quite
Dialogue: 0,0:09:53.28,0:09:58.94,Default,,0000,0000,0000,,a lot of increase. So adjusting to varying\Noptimal harvesting height is not only
Dialogue: 0,0:09:58.94,0:10:03.11,Default,,0000,0000,0000,,almost, but is really impossible for\Nconventional wind turbines. So one has to
Dialogue: 0,0:10:03.11,0:10:07.89,Default,,0000,0000,0000,,find another technology, which is better\Nand can give you access to this higher
Dialogue: 0,0:10:07.89,0:10:17.33,Default,,0000,0000,0000,,altitude winds. So this is the plot again\Nfrom before. So I have now a little bit
Dialogue: 0,0:10:17.33,0:10:22.27,Default,,0000,0000,0000,,motivated why the source is ubiquitous and\Ncontinuous. Now the question is, is it
Dialogue: 0,0:10:22.27,0:10:26.06,Default,,0000,0000,0000,,accessible, and how it is accessible. And\Nthis is the technological part which is
Dialogue: 0,0:10:26.06,0:10:33.05,Default,,0000,0000,0000,,called airborne wind energy. So how do we\Naccess these high altitude winds. So on
Dialogue: 0,0:10:33.05,0:10:37.40,Default,,0000,0000,0000,,for these, let's come back to the design\Nchallenges, which would be necessary to go
Dialogue: 0,0:10:37.40,0:10:43.05,Default,,0000,0000,0000,,to higher height. So high altitude means,\Nthat you just cannot just increase your
Dialogue: 0,0:10:43.05,0:10:48.56,Default,,0000,0000,0000,,tower, and have more torque on your\Nfoundation, and just scale up the system.
Dialogue: 0,0:10:48.56,0:10:52.86,Default,,0000,0000,0000,,So you should avoid proliferation of mass\Nand proliferation of the tower and
Dialogue: 0,0:10:52.86,0:10:57.30,Default,,0000,0000,0000,,foundation. And also, varying altitude\Nmeans you shouldn't have passive,
Dialogue: 0,0:10:57.30,0:11:03.85,Default,,0000,0000,0000,,stabilizing, static structures, but find\Nsomething which can vary. So just as an
Dialogue: 0,0:11:03.85,0:11:12.46,Default,,0000,0000,0000,,example here this is the sky walk in the\NGrand Canyon, and this is already a quite
Dialogue: 0,0:11:12.46,0:11:17.12,Default,,0000,0000,0000,,scary lever arm which you have. And if, in\Ncomparison, you take your modern wind
Dialogue: 0,0:11:17.12,0:11:21.00,Default,,0000,0000,0000,,turbine, you rotate it by 90 degrees, and\Ncompared it in size to this, you can see
Dialogue: 0,0:11:21.00,0:11:27.32,Default,,0000,0000,0000,,what kind of torque will be, like will act\Non the foundation. So this is already a
Dialogue: 0,0:11:27.32,0:11:34.35,Default,,0000,0000,0000,,very big piece of technology you have\Nhere. So we have to do better, and this is
Dialogue: 0,0:11:34.35,0:11:40.92,Default,,0000,0000,0000,,the second part, namely airborne wind\Nenergy, so the technology itself. So the
Dialogue: 0,0:11:40.92,0:11:46.42,Default,,0000,0000,0000,,first slide is probably the most important\Nof this part because it explains the
Dialogue: 0,0:11:46.42,0:11:51.77,Default,,0000,0000,0000,,idea behind this technology. So you take\Nautonomous drones, which are the most
Dialogue: 0,0:11:51.77,0:11:56.97,Default,,0000,0000,0000,,flexible connected to the ground via\Ntethers, and extract wind energy via these
Dialogue: 0,0:11:56.97,0:12:02.62,Default,,0000,0000,0000,,drones. So how does it work? So look at\Nthis conventional wind turbine here. You
Dialogue: 0,0:12:02.62,0:12:08.08,Default,,0000,0000,0000,,have most of the energy is produced by the\Nouter part of the wings. They are rotating
Dialogue: 0,0:12:08.08,0:12:11.86,Default,,0000,0000,0000,,with the highest velocity, and at the same\Ntime you have the highest the largest
Dialogue: 0,0:12:11.86,0:12:15.69,Default,,0000,0000,0000,,lever arm. So you produce most of the\Nenergy in the outer part. The inner part
Dialogue: 0,0:12:15.69,0:12:20.40,Default,,0000,0000,0000,,is more or less passive, stabilizing\Nstructure. So you remove that structure
Dialogue: 0,0:12:20.40,0:12:25.79,Default,,0000,0000,0000,,and replace it by something which is\Nflexible, and the first which comes to
Dialogue: 0,0:12:25.79,0:12:31.08,Default,,0000,0000,0000,,mind probably is a tether with which you\Nattach it to the ground. And then you have
Dialogue: 0,0:12:31.08,0:12:35.10,Default,,0000,0000,0000,,just the active part here, which is now an\Naircraft, moving in this circle, which
Dialogue: 0,0:12:35.10,0:12:41.55,Default,,0000,0000,0000,,before was circulated by the wing tips, to\Nextract your energy. This is the
Dialogue: 0,0:12:41.55,0:12:47.97,Default,,0000,0000,0000,,principle. So how do we bring down the\Npower when circulating this aircraft? So
Dialogue: 0,0:12:47.97,0:12:53.51,Default,,0000,0000,0000,,we have to, in some way, transform it to\Nelectric power. So there are, which are
Dialogue: 0,0:12:53.51,0:12:57.28,Default,,0000,0000,0000,,not shown in the picture before, lighter\Nthan air systems. So you just basically
Dialogue: 0,0:12:57.28,0:13:04.04,Default,,0000,0000,0000,,take a balloon, you put your wind turbine\Nat high altitude, and extract the power.
Dialogue: 0,0:13:04.04,0:13:09.19,Default,,0000,0000,0000,,And here the tether can clearly serve as\Nthe power line. But what we can also do is
Dialogue: 0,0:13:09.19,0:13:14.24,Default,,0000,0000,0000,,crosswind flight, which was shown in the\Npicture before. So here you have a moving
Dialogue: 0,0:13:14.24,0:13:19.25,Default,,0000,0000,0000,,aircraft, which can move in something\Nwhich is called the drag mode, meaning
Dialogue: 0,0:13:19.25,0:13:23.62,Default,,0000,0000,0000,,that you have onboard generators on the\Naircraft. So essentially it's a propeller
Dialogue: 0,0:13:23.62,0:13:28.83,Default,,0000,0000,0000,,aircraft, but the propellers are reversed\Nin repeller mode, so that the repellers
Dialogue: 0,0:13:28.83,0:13:33.05,Default,,0000,0000,0000,,produce energy for you. And then the\Ntether serves as power line. So this
Dialogue: 0,0:13:33.05,0:13:37.78,Default,,0000,0000,0000,,principle is shown here. So here you can\Nsee the generators and then the power is
Dialogue: 0,0:13:37.78,0:13:45.15,Default,,0000,0000,0000,,brought down by the tether. In the second\Npart, second strategy, is using the so
Dialogue: 0,0:13:45.15,0:13:51.26,Default,,0000,0000,0000,,called lift mode So here you have ground\Nbased generators and the tether itself
Dialogue: 0,0:13:51.26,0:13:55.36,Default,,0000,0000,0000,,transmits the power, there are no power\Nlines in the tether. So here you use that
Dialogue: 0,0:13:55.36,0:14:00.23,Default,,0000,0000,0000,,the power is given by the pulling force\Ntimes the reel out velocity of the tether.
Dialogue: 0,0:14:00.23,0:14:05.17,Default,,0000,0000,0000,,So you circulate in some patterns with\Nyour aircraft and you use the lift force
Dialogue: 0,0:14:05.17,0:14:10.06,Default,,0000,0000,0000,,acting on the aircraft to unreal this\Ntether from a drum, and at the drum, on
Dialogue: 0,0:14:10.06,0:14:14.90,Default,,0000,0000,0000,,the base station, there's a generator\Nattached which helps you to get the
Dialogue: 0,0:14:14.90,0:14:18.59,Default,,0000,0000,0000,,energy, to transform the energy into\Nelectrical energy. And of course, at some
Dialogue: 0,0:14:18.59,0:14:23.63,Default,,0000,0000,0000,,point the tether is maximally reeled out\Nand then you have to have to go to a reel
Dialogue: 0,0:14:23.63,0:14:28.40,Default,,0000,0000,0000,,in phase, where with minimal energy you\Nreel in the tether again, and start
Dialogue: 0,0:14:28.40,0:14:35.56,Default,,0000,0000,0000,,periodically this phase again. So these\Nare the concepts, and there's a whole zoo
Dialogue: 0,0:14:35.56,0:14:39.87,Default,,0000,0000,0000,,of airborne wind energy devices and\Nproposals, which show that this technology
Dialogue: 0,0:14:39.87,0:14:43.82,Default,,0000,0000,0000,,is still in a very early stage of being\Ndeveloped. So you have people here flying
Dialogue: 0,0:14:43.82,0:14:48.71,Default,,0000,0000,0000,,figure-of-eight patterns with the\Naircraft. So some things are lighter than
Dialogue: 0,0:14:48.71,0:14:53.41,Default,,0000,0000,0000,,air turbines, which look very exotic like\Nthis one, probably this one you have seen
Dialogue: 0,0:14:53.41,0:14:58.74,Default,,0000,0000,0000,,in media already. Proposals like this\Nhere. There are quad copters, which
Dialogue: 0,0:14:58.74,0:15:05.70,Default,,0000,0000,0000,,produce the energy by rotating of their,\Nof the propellers here. And all kind of
Dialogue: 0,0:15:05.70,0:15:15.65,Default,,0000,0000,0000,,exotic lever arm and aircrafts which you\Ncan use. So let's bring a little bit of
Dialogue: 0,0:15:15.65,0:15:21.63,Default,,0000,0000,0000,,more order into the technology, into the\Nproposals. And one of the things I want to
Dialogue: 0,0:15:21.63,0:15:27.21,Default,,0000,0000,0000,,discuss, which is very promising, is what\Nis called crosswind flight. So here as a
Dialogue: 0,0:15:27.21,0:15:32.74,Default,,0000,0000,0000,,example is a comparison of a conventional,\Nlighter-than-air system with the big wheel
Dialogue: 0,0:15:32.74,0:15:40.13,Default,,0000,0000,0000,,in London. So this is one of the biggest\Nwind turbines. And the harvesting area is,
Dialogue: 0,0:15:40.13,0:15:43.69,Default,,0000,0000,0000,,so the effective area of such a wind\Nturbine is the swept area of your
Dialogue: 0,0:15:43.69,0:15:48.59,Default,,0000,0000,0000,,propellers, essentially. So now let's look\Nwhat happens if you move an aircraft
Dialogue: 0,0:15:48.59,0:15:55.31,Default,,0000,0000,0000,,instead through the wind. Then the picture\Nof before is like of that size. And if you
Dialogue: 0,0:15:55.31,0:16:01.04,Default,,0000,0000,0000,,take an aircraft, which has the same wing\Narea as the wing areas of the propeller
Dialogue: 0,0:16:01.04,0:16:07.17,Default,,0000,0000,0000,,here, you're harvesting area is of that\Nsize. It's much bigger. And the reason for
Dialogue: 0,0:16:07.17,0:16:12.97,Default,,0000,0000,0000,,this is, that the effective area is now\Ngiven by the wing area times a
Dialogue: 0,0:16:12.97,0:16:17.39,Default,,0000,0000,0000,,coefficient, which is the square fraction\Nof the lift to drag coefficient of the
Dialogue: 0,0:16:17.39,0:16:21.53,Default,,0000,0000,0000,,aircraft times the lift coefficient\Nitself. And this factors of the order of
Dialogue: 0,0:16:21.53,0:16:30.69,Default,,0000,0000,0000,,200. So it increases the efficiency of\Nyour of your wings dramatically. This was
Dialogue: 0,0:16:30.69,0:16:38.77,Default,,0000,0000,0000,,already found by Loyd in 1980. And you can\Nnow ask "Why does it take 30 years from
Dialogue: 0,0:16:38.77,0:16:43.84,Default,,0000,0000,0000,,this idea to first systems?". And the\Nanswers is, in this community for is
Dialogue: 0,0:16:43.84,0:16:49.19,Default,,0000,0000,0000,,probably a very interesting is "Why are\Nthese prototypes are appearing only 30
Dialogue: 0,0:16:49.19,0:16:52.44,Default,,0000,0000,0000,,years later?". It's because sufficient\Ncomputer power. So for the control
Dialogue: 0,0:16:52.44,0:17:00.39,Default,,0000,0000,0000,,algorithms, which allow you to control\Nsuch flight modes, was not available. So,
Dialogue: 0,0:17:00.39,0:17:06.41,Default,,0000,0000,0000,,as an example, here's an illustration of\None of the current leaders in the field
Dialogue: 0,0:17:06.41,0:17:11.63,Default,,0000,0000,0000,,called AMPYX POWER, showing a crosswind\Nairborne wind energy system versus a
Dialogue: 0,0:17:11.63,0:17:15.50,Default,,0000,0000,0000,,conventional system. So here's the\Nconventional wind turbine for two
Dialogue: 0,0:17:15.50,0:17:20.01,Default,,0000,0000,0000,,megawatts. And the conventional this is a\Nconventional system. And the airborne wind
Dialogue: 0,0:17:20.01,0:17:26.10,Default,,0000,0000,0000,,system is, this is the ground station, and\Nthis is the aircraft. So one of the things
Dialogue: 0,0:17:26.10,0:17:32.07,Default,,0000,0000,0000,,which are, I mean, visible in this picture\Nis that it has much less like even sight
Dialogue: 0,0:17:32.07,0:17:35.71,Default,,0000,0000,0000,,impact in the environment. So having\Nsomething like this is much less
Dialogue: 0,0:17:35.71,0:17:39.95,Default,,0000,0000,0000,,disturbing from the even from the\Naesthetic point of view, than this huge
Dialogue: 0,0:17:39.95,0:17:47.98,Default,,0000,0000,0000,,wind turbine. So now the next step would\Nbe to look closer to the technology and
Dialogue: 0,0:17:47.98,0:17:53.63,Default,,0000,0000,0000,,see what are the AWE system components\Nthat you need, that you need to build such
Dialogue: 0,0:17:53.63,0:17:59.95,Default,,0000,0000,0000,,a device. So first of all, there is the\Ndrone or the fixed-wing aircraft. We have
Dialogue: 0,0:17:59.95,0:18:03.93,Default,,0000,0000,0000,,seen that it's very good to have large\Nlift and small drag coefficients, so you
Dialogue: 0,0:18:03.93,0:18:10.09,Default,,0000,0000,0000,,need something which is like a rigid\Nglider, more or less. On board you need
Dialogue: 0,0:18:10.09,0:18:16.94,Default,,0000,0000,0000,,sensors, like accelerometer, gyroscope,\NGPS, receiver, barometer, and a pitot tube
Dialogue: 0,0:18:16.94,0:18:25.08,Default,,0000,0000,0000,,to measure the air the air speed. And this\Nis to determine the system state, that
Dialogue: 0,0:18:25.08,0:18:30.20,Default,,0000,0000,0000,,then is like reacted on by the control\Nsurfaces, in the case of an aircraft by
Dialogue: 0,0:18:30.20,0:18:34.71,Default,,0000,0000,0000,,ailerons flaps and the rudder. Moreover,\Nyou need of course a microcontroller and
Dialogue: 0,0:18:34.71,0:18:40.73,Default,,0000,0000,0000,,algorithms which do the state estimation.\NSo from the sensor data they compute the
Dialogue: 0,0:18:40.73,0:18:46.02,Default,,0000,0000,0000,,state of the system, meaning it's\Nposition, altitude, velocity. And you have
Dialogue: 0,0:18:46.02,0:18:51.43,Default,,0000,0000,0000,,to navigate. So and of course you might\Nneed something like a propeller for
Dialogue: 0,0:18:51.43,0:18:59.07,Default,,0000,0000,0000,,takeoff, landing, and energy generation in\Ncase of drag mode. The second thing is of
Dialogue: 0,0:18:59.07,0:19:03.34,Default,,0000,0000,0000,,course the ground station. So here you\Nneed the drum for tether wind-up. You need
Dialogue: 0,0:19:03.34,0:19:08.56,Default,,0000,0000,0000,,a motor which eventually has to be\Ntransformed into generator mode if you
Dialogue: 0,0:19:08.56,0:19:12.41,Default,,0000,0000,0000,,have the lift mode. You need power\Nconverters, also microcontrollers and
Dialogue: 0,0:19:12.41,0:19:16.51,Default,,0000,0000,0000,,algorithms which synchronize your ground-\Nstation operation with the drone; and you
Dialogue: 0,0:19:16.51,0:19:22.30,Default,,0000,0000,0000,,need a runway, catapult or something alike\Nfor takeoff and landing. So far it looks
Dialogue: 0,0:19:22.30,0:19:28.32,Default,,0000,0000,0000,,quite simple, but the devil is in the\Ndetail. And here I found a nice quote a
Dialogue: 0,0:19:28.32,0:19:33.51,Default,,0000,0000,0000,,colleague of mine – (uninteligble name) – \Nhas done in one of his talks,
Dialogue: 0,0:19:33.51,0:19:37.17,Default,,0000,0000,0000,,and I liked it very much because it\Ndisplays very well what challenges have to
Dialogue: 0,0:19:37.17,0:19:42.60,Default,,0000,0000,0000,,be still overcome. So it starts with\N"Theory is when nothing works but everyone
Dialogue: 0,0:19:42.60,0:19:48.10,Default,,0000,0000,0000,,knows why." and to demonstrate this let's\Nhave a look at this video here which is
Dialogue: 0,0:19:48.10,0:19:56.54,Default,,0000,0000,0000,,one of the flight attempts of one of the\Ncompanies: So the aircraft lifts off,
Dialogue: 0,0:19:56.54,0:19:58.64,Default,,0000,0000,0000,,there's no sound … yet. Now there is\Nsound.
Dialogue: 0,0:19:58.64,0:20:02.74,Default,,0000,0000,0000,,{\i1}Background music of shown video{\i0}
Dialogue: 0,0:20:02.74,0:20:05.03,Default,,0000,0000,0000,,Speaker in shown video:\NAbort! Abort! Abort!
Dialogue: 0,0:20:05.03,0:20:07.90,Default,,0000,0000,0000,,{\i1}Soft laughter{\i0}
Dialogue: 0,0:20:07.90,0:20:13.11,Default,,0000,0000,0000,,Christoph: Yeah. And the desperation of\Nthe founder was clearly hearable at the
Dialogue: 0,0:20:13.11,0:20:16.75,Default,,0000,0000,0000,,end. And you could see that the tether\Nruptured. And then there was no way to
Dialogue: 0,0:20:16.75,0:20:23.12,Default,,0000,0000,0000,,recover that most of the aircraft was\Nlost. Second: "Sometimes practice is when
Dialogue: 0,0:20:23.12,0:20:27.13,Default,,0000,0000,0000,,everything works but no one knows why." So\Nthere are also positive surprises. And
Dialogue: 0,0:20:27.13,0:20:33.33,Default,,0000,0000,0000,,here is a launch, a catapult launch, for\Nan aircraft which now uses weight.
Dialogue: 0,0:20:33.33,0:20:43.29,Default,,0000,0000,0000,,{\i1}Background noise of shown video{\i0}\N{\i1}Laughter{\i0}
Dialogue: 0,0:20:43.29,0:20:48.36,Default,,0000,0000,0000,,Christoph: So a positive surprise for a\Ntest. And finally, sometimes if you
Dialogue: 0,0:20:48.36,0:20:52.70,Default,,0000,0000,0000,,combine theory and practice then "nothing\Nworks but no one knows why". This is where
Dialogue: 0,0:20:52.70,0:20:57.21,Default,,0000,0000,0000,,the complication really is: The devil is\Nin the detail. And here you can see a
Dialogue: 0,0:20:57.21,0:21:00.65,Default,,0000,0000,0000,,video from a flight which is crosswind\Nflight: Everything seems normal …
Dialogue: 0,0:21:00.65,0:21:14.45,Default,,0000,0000,0000,,{\i1}Dramatic background music of shown video{\i0}\NChristoph: … and then the prototype is
Dialogue: 0,0:21:14.45,0:21:23.38,Default,,0000,0000,0000,,again lost. So this is complicated. So but\Nthere is a lot of progress and so I want
Dialogue: 0,0:21:23.38,0:21:28.38,Default,,0000,0000,0000,,to come closely, very quickly introduce\Nthe current industrial status. So I focus
Dialogue: 0,0:21:28.38,0:21:32.36,Default,,0000,0000,0000,,on three companies which work on that: So\None of them is Enerkite in Berlin, and
Dialogue: 0,0:21:32.36,0:21:36.64,Default,,0000,0000,0000,,they have now a system which is basically\Nstationed on such a truck and this is a
Dialogue: 0,0:21:36.64,0:21:41.66,Default,,0000,0000,0000,,crosswind system of a passive wing. So it\Nsteered via three tethers and it produces
Dialogue: 0,0:21:41.66,0:21:47.71,Default,,0000,0000,0000,,up to 30 kilowatts of energy. Then you\Nhave Ampyx Power. They have here the
Dialogue: 0,0:21:47.71,0:21:51.58,Default,,0000,0000,0000,,launching site in the Netherlands and they\Nare currently producing this aircraft
Dialogue: 0,0:21:51.58,0:21:58.21,Default,,0000,0000,0000,,here. This type which is a crosswind\Nsystem in lift mode. And at the end will
Dialogue: 0,0:21:58.21,0:22:04.10,Default,,0000,0000,0000,,produce up to 250 kilowatts of power. This\Nis under construction. And, finally, there
Dialogue: 0,0:22:04.10,0:22:10.93,Default,,0000,0000,0000,,is Google X Makani in California. And they\Nhave built a drag-mode aircraft – here –
Dialogue: 0,0:22:10.93,0:22:15.75,Default,,0000,0000,0000,,which is flying. And I can show you a\Nvideo that they have on their home page –
Dialogue: 0,0:22:15.75,0:22:21.80,Default,,0000,0000,0000,,very nicely. Where they show a flight so\Nthat you can see that the 600 kilowatt
Dialogue: 0,0:22:21.80,0:22:26.70,Default,,0000,0000,0000,,system is working. Here you see the\Nonboard propellers. You can see the
Dialogue: 0,0:22:26.70,0:22:32.57,Default,,0000,0000,0000,,tether. Down here this is from the tether\Nattachment point. So the things are
Dialogue: 0,0:22:32.57,0:22:42.97,Default,,0000,0000,0000,,working. There are prototypes. But one of\Nthe things which are important is: one has
Dialogue: 0,0:22:42.97,0:22:47.30,Default,,0000,0000,0000,,to "test, test, test" and get experience\Nfrom tests. So "experience is what you get
Dialogue: 0,0:22:47.30,0:22:52.48,Default,,0000,0000,0000,,when you were expecting something else".\NYou really. So what does it mean? So we
Dialogue: 0,0:22:52.48,0:22:57.30,Default,,0000,0000,0000,,have to test, analyze, adapt the systems.\NSo because many – as you could see from
Dialogue: 0,0:22:57.30,0:23:01.43,Default,,0000,0000,0000,,this design variations in the zoo which\NI've shown – many of the concepts are
Dialogue: 0,0:23:01.43,0:23:06.56,Default,,0000,0000,0000,,still open. So for example the design of\Nthe airframe. If you use a biplane, a
Dialogue: 0,0:23:06.56,0:23:10.19,Default,,0000,0000,0000,,flying wing or anything alike – or\Nsomething totally different – is still
Dialogue: 0,0:23:10.19,0:23:14.86,Default,,0000,0000,0000,,open. The tether construction – what kind\Nof materials to use – is still open. The
Dialogue: 0,0:23:14.86,0:23:20.59,Default,,0000,0000,0000,,materials in itself is still open for the\Naircraft etc. etc.. The mode of operation
Dialogue: 0,0:23:20.59,0:23:25.07,Default,,0000,0000,0000,,– that means takeoff, landing and direct\Nversus lift mode – is still an open
Dialogue: 0,0:23:25.07,0:23:30.30,Default,,0000,0000,0000,,question. What is the best thing to\Nrealize for industrial products? And then
Dialogue: 0,0:23:30.30,0:23:34.65,Default,,0000,0000,0000,,control hardware and software algorithms\Nhave to be tested thoroughly. Of course
Dialogue: 0,0:23:34.65,0:23:40.72,Default,,0000,0000,0000,,it'd have to be certified by the aerospace\Nagencies, of course. You want to have a
Dialogue: 0,0:23:40.72,0:23:46.12,Default,,0000,0000,0000,,failsafe. So what you have to do is you\Nwant to even, I mean, have total losses in
Dialogue: 0,0:23:46.12,0:23:49.98,Default,,0000,0000,0000,,experiment. You want to do the experiments\Nwich would lead to a total loss of your
Dialogue: 0,0:23:49.98,0:23:56.21,Default,,0000,0000,0000,,system. So here comes the idea that\Ninstead you should build a cheap and
Dialogue: 0,0:23:56.21,0:24:01.95,Default,,0000,0000,0000,,disposable test platform instead of a\Nlargely scaled-up system first, before you
Dialogue: 0,0:24:01.95,0:24:05.86,Default,,0000,0000,0000,,build the expensive prototype and do tests\Non them. And this brought us to the idea
Dialogue: 0,0:24:05.86,0:24:10.56,Default,,0000,0000,0000,,to provide a low-cost open-source test\Nplatform where everybody at home can build
Dialogue: 0,0:24:10.56,0:24:15.89,Default,,0000,0000,0000,,his own wind drone. And this is the third\Npart of the talk. So the do-it-yourself
Dialogue: 0,0:24:15.89,0:24:24.34,Default,,0000,0000,0000,,wind drone. What are the ingredients here?\NSo first you need a drone, so here I want
Dialogue: 0,0:24:24.34,0:24:29.12,Default,,0000,0000,0000,,to show the airframe and reinforcement\Nhack which is necessary to prepare your
Dialogue: 0,0:24:29.12,0:24:33.33,Default,,0000,0000,0000,,airframe for the additional forces by\Nadding the tether. Then there's a ground
Dialogue: 0,0:24:33.33,0:24:37.74,Default,,0000,0000,0000,,station and here I want to motivate why\Nthe drone is essentially behaving like a
Dialogue: 0,0:24:37.74,0:24:44.11,Default,,0000,0000,0000,,fish – in this case a barracuda. The next\Nthing is navigation on curved manifold is
Dialogue: 0,0:24:44.11,0:24:48.68,Default,,0000,0000,0000,,very important because you have like a\Nconstraint coming from the tether. And
Dialogue: 0,0:24:48.68,0:24:54.10,Default,,0000,0000,0000,,finally you need something for control\Nwhich is the autopilot. So in this case
Dialogue: 0,0:24:54.10,0:25:01.12,Default,,0000,0000,0000,,it's the ardupilot open-source project\Nwhich we adapted. So let's come to the
Dialogue: 0,0:25:01.12,0:25:05.89,Default,,0000,0000,0000,,airframe-reinforcement-hack. So what you\Nuse: Take your favourite polystyrene
Dialogue: 0,0:25:05.89,0:25:11.29,Default,,0000,0000,0000,,airframe – so in this case it's an Easy\NStar II – and glue the wings together.
Dialogue: 0,0:25:11.29,0:25:15.58,Default,,0000,0000,0000,,This is the lower side of the wings. You\Nput in there a carbon rod – here in this
Dialogue: 0,0:25:15.58,0:25:21.14,Default,,0000,0000,0000,,part – and you stabilize it with racks\Nwhich you glue into the slits we can see
Dialogue: 0,0:25:21.14,0:25:29.18,Default,,0000,0000,0000,,here. And then you wrap carbon in the\Nforward part of it where the most of the
Dialogue: 0,0:25:29.18,0:25:35.79,Default,,0000,0000,0000,,aerodynamic force is attached. Then you\Nhave the carbon ???? ???? wind around your
Dialogue: 0,0:25:35.79,0:25:44.32,Default,,0000,0000,0000,,tether. And you install additional tubes\Nfor fixing the wings on the fuselage. So
Dialogue: 0,0:25:44.32,0:25:48.61,Default,,0000,0000,0000,,the fuselage is here. We cut off the\Nengine blocks, included additional carbon
Dialogue: 0,0:25:48.61,0:25:52.64,Default,,0000,0000,0000,,rods. So you can put these carbon rods on\Nthese carbon rods here, and fix everything
Dialogue: 0,0:25:52.64,0:25:59.57,Default,,0000,0000,0000,,with screws. So to show you how that looks\Nlike and what are the size of this model
Dialogue: 0,0:25:59.57,0:26:05.80,Default,,0000,0000,0000,,is: So here is the original-size aircraft\Nwith carbon. And you can later – if you
Dialogue: 0,0:26:05.80,0:26:15.33,Default,,0000,0000,0000,,want – pass by the assembly area and look\Nat it and have a look at it and touch it.
Dialogue: 0,0:26:15.33,0:26:20.58,Default,,0000,0000,0000,,So this is how it looks decomposed into\Ndifferent components: So again wings and
Dialogue: 0,0:26:20.58,0:26:27.27,Default,,0000,0000,0000,,so on and so on, the servos for the\Ncontrol surfaces. The central unit here is
Dialogue: 0,0:26:27.27,0:26:33.15,Default,,0000,0000,0000,,the Pixhawk autopilot. So there's a\Nmicrocontroller which contains some of the
Dialogue: 0,0:26:33.15,0:26:37.34,Default,,0000,0000,0000,,sensors: You have a GPS sensor, in\Naddition you have a telemetry antenna for
Dialogue: 0,0:26:37.34,0:26:45.83,Default,,0000,0000,0000,,data – for data transfer to the ground\Nstation. And you have RC control for
Dialogue: 0,0:26:45.83,0:26:51.58,Default,,0000,0000,0000,,manual control when you switch out of auto\Nmode to have manual control in emergency
Dialogue: 0,0:26:51.58,0:26:58.74,Default,,0000,0000,0000,,situations – or if you want to make other\Nkind of flight tests. So now this is the
Dialogue: 0,0:26:58.74,0:27:02.56,Default,,0000,0000,0000,,drone itself. So now is the question what\Nto do with the ground station. And here
Dialogue: 0,0:27:02.56,0:27:09.25,Default,,0000,0000,0000,,let's look why the drone behaves as a\Nfish: Because what it does is, like in
Dialogue: 0,0:27:09.25,0:27:13.06,Default,,0000,0000,0000,,fishing, you would need a free-moving\Ntether; it has to be fast and fail-safe
Dialogue: 0,0:27:13.06,0:27:16.89,Default,,0000,0000,0000,,reeled in and reeled out; and it should\Nremain twist free so that it doesn't give
Dialogue: 0,0:27:16.89,0:27:21.49,Default,,0000,0000,0000,,any knots if it is not under tension. And\Nthe thing which we came up with wich best
Dialogue: 0,0:27:21.49,0:27:27.56,Default,,0000,0000,0000,,serves for our needs at the moment is an\Noff-shore fishing reel.
Dialogue: 0,0:27:27.56,0:27:33.77,Default,,0000,0000,0000,,{\i1}Applause{\i0}\NChristoph: So and you need offshore here
Dialogue: 0,0:27:33.77,0:27:37.89,Default,,0000,0000,0000,,because the drum has to be perpendicular\Nto the rod: This guarantees you like
Dialogue: 0,0:27:37.89,0:27:42.75,Default,,0000,0000,0000,,reload phases twist free on the\Ntether. Other fishing rods have the drum
Dialogue: 0,0:27:42.75,0:27:47.55,Default,,0000,0000,0000,,aligned with the rod, and then you\Naccumulate twist on the tether which can
Dialogue: 0,0:27:47.55,0:27:52.77,Default,,0000,0000,0000,,lead to knots, lead to knots and then …\Nit's not a good idea. It will destroy your
Dialogue: 0,0:27:52.77,0:27:56.95,Default,,0000,0000,0000,,tether. So and this is the first flight\Ntest. So we were very enthusiastic and
Dialogue: 0,0:27:56.95,0:28:02.65,Default,,0000,0000,0000,,started the first flight test. And here it\Nis.
Dialogue: 0,0:28:02.65,0:28:13.15,Default,,0000,0000,0000,,{\i1}Indistinct voice in shown video{\i0}\NVoice in shown video: OK. … Hinterher?
Dialogue: 0,0:28:13.15,0:28:15.14,Default,,0000,0000,0000,,{\i1}Laughter{\i0}\NVisv: Versuch mal rauszugehen. Manual?
Dialogue: 0,0:28:15.14,0:28:17.79,Default,,0000,0000,0000,,Achtung, Achtung! Versuch ihn zu fangen.\NNa gut.
Dialogue: 0,0:28:17.79,0:28:19.78,Default,,0000,0000,0000,,{\i1}Beeping in shown video{\i0}\NChristoph: OK.
Dialogue: 0,0:28:19.78,0:28:23.26,Default,,0000,0000,0000,,{\i1}Laughter{\i0}\NChristoph: So unfortunately it did not
Dialogue: 0,0:28:23.26,0:28:27.62,Default,,0000,0000,0000,,work.\N{\i1}Applause{\i0}
Dialogue: 0,0:28:27.62,0:28:34.72,Default,,0000,0000,0000,,Christoph: So what happens? This was the\Nresult: The tail was broken. And because
Dialogue: 0,0:28:34.72,0:28:38.75,Default,,0000,0000,0000,,the tether apparently wrapped around the\Nback of the aircraft and then it became
Dialogue: 0,0:28:38.75,0:28:42.70,Default,,0000,0000,0000,,uncontrollable. So we came up with what do\Nwe do: If you don't know any further, any
Dialogue: 0,0:28:42.70,0:28:47.70,Default,,0000,0000,0000,,better, use carbon! So we put some carbon\Non the lower part of the of the fuselage
Dialogue: 0,0:28:47.70,0:28:53.50,Default,,0000,0000,0000,,to reinforce it. And then of course you\Nhave to think about writing your
Dialogue: 0,0:28:53.50,0:29:00.02,Default,,0000,0000,0000,,navigation code, to navigate if you are\Nunder tethered flight. So here is the
Dialogue: 0,0:29:00.02,0:29:05.36,Default,,0000,0000,0000,,receipe for how to do it: So first you\Ntake one git clone of ardupilot – this
Dialogue: 0,0:29:05.36,0:29:09.02,Default,,0000,0000,0000,,autumn open-source software. You\Ntake one curved 2-dimensional manifold –
Dialogue: 0,0:29:09.02,0:29:13.70,Default,,0000,0000,0000,,it's essentially giving us a hypersurface\Nembedded in 3-dimensional Euclidean space.
Dialogue: 0,0:29:13.70,0:29:18.22,Default,,0000,0000,0000,,In case of constant tether length this is\Njust a semi-hemisphere as to which is
Dialogue: 0,0:29:18.22,0:29:22.16,Default,,0000,0000,0000,,centered around your ground station. Then\Nyou take a planar curve which you want to
Dialogue: 0,0:29:22.16,0:29:28.07,Default,,0000,0000,0000,,fly along – or curved segments – and a\Npinch of Differential Geometry to wrap it
Dialogue: 0,0:29:28.07,0:29:32.23,Default,,0000,0000,0000,,on the sphere, to make this curve\Nappearing on the sphere. You take a little
Dialogue: 0,0:29:32.23,0:29:38.28,Default,,0000,0000,0000,,bit of Classical Mechanics for the flight\Ncontrol to transfer the curve
Dialogue: 0,0:29:38.28,0:29:45.55,Default,,0000,0000,0000,,accelerations into actually control-\Nsurface motions. And then you need, of
Dialogue: 0,0:29:45.55,0:29:51.56,Default,,0000,0000,0000,,course, 12 dozen coffee for doing so. You\Nput everything together into – of course
Dialogue: 0,0:29:51.56,0:29:55.62,Default,,0000,0000,0000,,not the coffee – into the computer algebra\Nsystem and stir well, and let the CPU bake
Dialogue: 0,0:29:55.62,0:30:03.56,Default,,0000,0000,0000,,it at 100 degrees, and then you come up\Nwith a smooth – at least C¹ – curve.
Dialogue: 0,0:30:03.56,0:30:09.35,Default,,0000,0000,0000,,{\i1}Applause{\i0}\NChristoph: So the curve is shown here. So
Dialogue: 0,0:30:09.35,0:30:13.82,Default,,0000,0000,0000,,it's … this is one part of a figure-8\Npattern. So the other part would be behind
Dialogue: 0,0:30:13.82,0:30:17.95,Default,,0000,0000,0000,,here. It's composed of two geodesic\Nsegments and one turning segment and they
Dialogue: 0,0:30:17.95,0:30:21.72,Default,,0000,0000,0000,,are C¹ glued together here. And these are\Nthe equations: So you can find in the
Dialogue: 0,0:30:21.72,0:30:26.90,Default,,0000,0000,0000,,paper – I don't want to go into detail. So\Nnow you have to modify the source code of
Dialogue: 0,0:30:26.90,0:30:31.45,Default,,0000,0000,0000,,this ardupilot project. So here there are\Nhighlighted the patterns which you
Dialogue: 0,0:30:31.45,0:30:35.29,Default,,0000,0000,0000,,basically have to … where you have to do\Nmodifications: You have to implement new
Dialogue: 0,0:30:35.29,0:30:42.14,Default,,0000,0000,0000,,flight modes and change some of the\Ncontrol algorithms. And then you come up
Dialogue: 0,0:30:42.14,0:30:49.50,Default,,0000,0000,0000,,with the next flight test. And here is the\Nnext attempt.
Dialogue: 0,0:30:49.50,0:31:11.39,Default,,0000,0000,0000,,{\i1}Music and propellor sounds{\i0}\NVoice in shown video: Beim Auswerten
Dialogue: 0,0:31:11.39,0:31:28.91,Default,,0000,0000,0000,,müssen wir sehen, ob wir dann verschiedene\Nwählen.
Dialogue: 0,0:31:28.91,0:31:35.48,Default,,0000,0000,0000,,{\i1}Music ends{\i0}\N{\i1}Applause{\i0}
Dialogue: 0,0:31:35.48,0:31:41.16,Default,,0000,0000,0000,,Christoph: The whistling sound you have\Nheard at the end is the tether being
Dialogue: 0,0:31:41.16,0:31:45.26,Default,,0000,0000,0000,,dragged through the air. So there was\Nreally tension on the tether. And you can
Dialogue: 0,0:31:45.26,0:31:50.02,Default,,0000,0000,0000,,also see this if you do a data analysis on\Nthe flight data later. So yes for example
Dialogue: 0,0:31:50.02,0:31:54.54,Default,,0000,0000,0000,,multiple possibilities. You have a lot of\Ndata which is possible to analyze. So the
Dialogue: 0,0:31:54.54,0:31:59.61,Default,,0000,0000,0000,,autopilot this was very very it's very\Nvery nicely done in this open-source
Dialogue: 0,0:31:59.61,0:32:04.21,Default,,0000,0000,0000,,project: So they have a data file with all\Nprimary and secondary data you can use for
Dialogue: 0,0:32:04.21,0:32:08.05,Default,,0000,0000,0000,,your analysis. So for instance this is the\Nflight curve of different flight modes
Dialogue: 0,0:32:08.05,0:32:11.92,Default,,0000,0000,0000,,which we used. You have the altitude of\Nthe aircraft, you can look to deviations
Dialogue: 0,0:32:11.92,0:32:16.44,Default,,0000,0000,0000,,in radial and transverse directions. You\Ncan look to tether tension – or like a
Dialogue: 0,0:32:16.44,0:32:20.62,Default,,0000,0000,0000,,measure for tether tension – by looking to\Nthe length variation of the tether. And
Dialogue: 0,0:32:20.62,0:32:26.52,Default,,0000,0000,0000,,you can of course do time series analysis\Nof how your figure-8 pattern has flown
Dialogue: 0,0:32:26.52,0:32:33.62,Default,,0000,0000,0000,,along. And that is what you can do with\Nthis very very nice autopilot open-source
Dialogue: 0,0:32:33.62,0:32:40.36,Default,,0000,0000,0000,,software which is available when … written\Nby many many people on the internet. So
Dialogue: 0,0:32:40.36,0:32:44.02,Default,,0000,0000,0000,,the question which remains is: After all\Nof this is, will it be a fail-safe to
Dialogue: 0,0:32:44.02,0:32:49.93,Default,,0000,0000,0000,,100%? And the answer is nope, it will not!\NIt will … there will be of course
Dialogue: 0,0:32:49.93,0:32:56.85,Default,,0000,0000,0000,,accidents happen. But the thing is:\NNothing is failsafe. And so here's a
Dialogue: 0,0:32:56.85,0:33:00.96,Default,,0000,0000,0000,,standard wind turbine and look for\Nyourself.
Dialogue: 0,0:33:00.96,0:33:06.07,Default,,0000,0000,0000,,{\i1}Laughter{\i0}\NChristoph: You see there is no 100%
Dialogue: 0,0:33:06.07,0:33:15.48,Default,,0000,0000,0000,,guarantee, but we have to try very hard to\Nget it as failsave as possible. So yeah
Dialogue: 0,0:33:15.48,0:33:20.22,Default,,0000,0000,0000,,this is essentially it. That was the talk.\NSo what I want to say is that the current
Dialogue: 0,0:33:20.22,0:33:28.92,Default,,0000,0000,0000,,status of airborne wind energy can be seen\Nhere by a nice book on the Springer page
Dialogue: 0,0:33:28.92,0:33:33.50,Default,,0000,0000,0000,,which you can download here. And we are\Nvery very happy to have any kind of
Dialogue: 0,0:33:33.50,0:33:38.28,Default,,0000,0000,0000,,critical remarks, input to help in\Ndeveloping the system further. So please
Dialogue: 0,0:33:38.28,0:33:41.86,Default,,0000,0000,0000,,if you want, look to this web page,\Nthere's a lot of information including a
Dialogue: 0,0:33:41.86,0:33:48.45,Default,,0000,0000,0000,,paper and we will be very happy for any\Nkind of help. And finally I would again
Dialogue: 0,0:33:48.45,0:33:52.28,Default,,0000,0000,0000,,stress that we could rely on this\Ntremendous work of the open-source
Dialogue: 0,0:33:52.28,0:33:56.71,Default,,0000,0000,0000,,community working on this autopilot\Nproject that has helped us to realize this
Dialogue: 0,0:33:56.71,0:34:02.03,Default,,0000,0000,0000,,project in very short time; so very happy\Nabout this. And I want to thank of course
Dialogue: 0,0:34:02.03,0:34:07.04,Default,,0000,0000,0000,,Phillip Bechtle, who is here, and Thomas\NGehrmann and Maximillian Schulz-Herberg,
Dialogue: 0,0:34:07.04,0:34:11.25,Default,,0000,0000,0000,,the students, and Udo Zillmann, who can\Nnot be here, for working on this project
Dialogue: 0,0:34:11.25,0:34:14.98,Default,,0000,0000,0000,,and putting so much work also into it.\NThank you very much for your attention!
Dialogue: 0,0:34:14.98,0:34:17.23,Default,,0000,0000,0000,,{\i1}Applause{\i0}
Dialogue: 0,0:34:17.23,0:34:27.67,Default,,0000,0000,0000,,H: We can have two more on the microphones
Dialogue: 0,0:34:27.67,0:34:32.90,Default,,0000,0000,0000,,here and here – one and five – so two\Nquestions. The first one, please!
Dialogue: 0,0:34:32.90,0:34:37.38,Default,,0000,0000,0000,,Question: So you talk, so you talked a lot\Nabout powered – and not powered –, but
Dialogue: 0,0:34:37.38,0:34:41.59,Default,,0000,0000,0000,,controlled flight. How does it compare –\Nenergy wise – to uncontrolled flight?
Dialogue: 0,0:34:41.59,0:34:46.40,Default,,0000,0000,0000,,Basically putting a propellor on a kite?\NAnswer: So the thing is the propellor on
Dialogue: 0,0:34:46.40,0:34:53.91,Default,,0000,0000,0000,,the kite … with kite you mean, I guess,\Nnon-rigid structures. So meaning that the
Dialogue: 0,0:34:53.91,0:35:00.08,Default,,0000,0000,0000,,first question is how do you want to put a\Npropeller on a kite if it's non rigid. So
Dialogue: 0,0:35:00.08,0:35:07.03,Default,,0000,0000,0000,,that is a question which goes back to you.\NSo because that is something is not clear
Dialogue: 0,0:35:07.03,0:35:12.17,Default,,0000,0000,0000,,to me. But in any case rigid air\Nframe is harder to control than a
Dialogue: 0,0:35:12.17,0:35:17.16,Default,,0000,0000,0000,,kite. So there are people who work with a\Nkite. And by kite surfing or if you do
Dialogue: 0,0:35:17.16,0:35:21.74,Default,,0000,0000,0000,,like steer normal kites from the ground.\NYou know it's like moving not that fast in
Dialogue: 0,0:35:21.74,0:35:27.13,Default,,0000,0000,0000,,the wind field, so it's easier to control.\NThis is a big benefit of kites. And also
Dialogue: 0,0:35:27.13,0:35:32.41,Default,,0000,0000,0000,,the weight is a big benefit. But the power\Noutput – because of the bad or worse lift-
Dialogue: 0,0:35:32.41,0:35:37.60,Default,,0000,0000,0000,,to-drag coefficient – is unfortunately not\Nthat efficient as a rigid aircraft. So you
Dialogue: 0,0:35:37.60,0:35:42.28,Default,,0000,0000,0000,,want to go to the rigid air craft.\NH: If you leave the room now, please be
Dialogue: 0,0:35:42.28,0:35:45.81,Default,,0000,0000,0000,,quiet because we have questions and\Nanswers here! Number three please, and
Dialogue: 0,0:35:45.81,0:35:50.40,Default,,0000,0000,0000,,that is the last question I'm afraid. But\Nyou can ask questions after the talk.
Dialogue: 0,0:35:50.40,0:35:57.89,Default,,0000,0000,0000,,Q: I want to go back to the space part. I\Nwas wondering … there are some ideas about
Dialogue: 0,0:35:57.89,0:36:03.04,Default,,0000,0000,0000,,bootstrapping like a solar station on the\Nmoon and then like shipping, I don't know,
Dialogue: 0,0:36:03.04,0:36:08.48,Default,,0000,0000,0000,,hydrogen or like pre-charged lithium\Nbatteries back to earth and back and
Dialogue: 0,0:36:08.48,0:36:14.36,Default,,0000,0000,0000,,forth. Is it like realistic or not really?\NA by Anja Kohfeldt (previous talk): I
Dialogue: 0,0:36:14.36,0:36:19.28,Default,,0000,0000,0000,,think also this approach would be quite\Nexpensive. And you have to install this
Dialogue: 0,0:36:19.28,0:36:25.63,Default,,0000,0000,0000,,infrastructure on the moon first, and you\Nhave to establish the flight base back and
Dialogue: 0,0:36:25.63,0:36:30.84,Default,,0000,0000,0000,,forward. Realistic is a thing, you know.\NAt the end that's a question of money and
Dialogue: 0,0:36:30.84,0:36:38.01,Default,,0000,0000,0000,,investment. And I'm not sure whether this\Nwould pay out, but we haven't analyzed
Dialogue: 0,0:36:38.01,0:36:44.50,Default,,0000,0000,0000,,this kind of approaches, yet.\NH: Thank you! So thank you very very much
Dialogue: 0,0:36:44.50,0:36:53.10,Default,,0000,0000,0000,,Stefan, Anja and Christoph! Give them a\Nwarm applause again please!
Dialogue: 0,0:36:53.10,0:36:57.21,Default,,0000,0000,0000,,{\i1}Applause{\i0}\NStefan: Thank you!
Dialogue: 0,0:36:57.21,0:37:01.75,Default,,0000,0000,0000,,{\i1}Outro music{\i0}
Dialogue: 0,0:37:01.75,0:37:14.24,Default,,0000,0000,0000,,subtitles created by c3subtitles.de\Nin the year 2019. Join, and help us!