[HN Gopher] Dynamic soaring
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Dynamic soaring
Author : KolmogorovComp
Score : 59 points
Date : 2023-12-17 11:49 UTC (11 hours ago)
(HTM) web link (en.wikipedia.org)
(TXT) w3m dump (en.wikipedia.org)
| stavros wrote:
| Here's what it looks like:
| https://www.youtube.com/watch?v=0nyYaL0dGAA
| jessriedel wrote:
| Here's a really wonderful talk by Spencer Lisenby about the
| basic physics and Lisenby's work on pushing the speed
| https://www.youtube.com/watch?v=nv7-YM4wno8
|
| Some other interesting HN comments:
|
| https://news.ycombinator.com/item?id=32739679
| https://news.ycombinator.com/item?id=38653688
| adolph wrote:
| The Lisenby lecture is excellent.
| codethief wrote:
| Great article with some more background:
|
| https://newatlas.com/aircraft/dynamic-soaring-speed-record-s...
| croemer wrote:
| Was about to share this here ;) RC glider going at nearly the
| speed of sound. Crazy!
| https://youtu.be/0nyYaL0dGAA?si=BM_M8ZkUEhoTLshk
| JKCalhoun wrote:
| Amazing. I am having a hard time though separating dynamic
| soaring from ordinary slope soaring. I'll have to keep thinking
| on it until I understand it.
|
| Edit: very cool. I watched the video referenced in the HN
| comments (BTD10: The 835kph Sailplane and Dynamic Soaring) and
| I get it.
| stavros wrote:
| Slope soaring is just riding a current that's going up
| because it hits a slope. Dynamic soaring is taking advantage
| of two masses of air of different speeds so you get a bunch
| of free airspeed as soon as you cross their barrier.
|
| Say you have a glider with a 2 m/s headwind. If you cross
| into a wind mass that's a 10m/s headwind, you've just gained
| 8 m/s of airspeed for free. Rinse and repeat.
| EdwardCoffin wrote:
| The third part of Neal Stephenson's novel _Seveneves_ [1] has a
| neat application of this.
|
| [1] https://en.wikipedia.org/wiki/Seveneves
| taneq wrote:
| Ooh, sounds like what alba- oh here's the section on albatrosses.
| Super interesting, I was always dubious of those claims of "this
| bird only lands every 6 months" and the like, then I learned
| about the spiral glide pattern between two layers of windshear.
| It's fascinating (if no longer suprising) all the ways that
| nature has learned to harvest energy from the environment.
| tim333 wrote:
| While they only return to land occasionally they do land on the
| sea sometimes and need to go to it to feed and drink.
|
| On the other hand Swifts apparently can stay up for months.
| They eat flying insects so can stay in the air.
| https://www.latimes.com/science/sciencenow/la-sci-sn-common-...
| cedws wrote:
| I've been watching a lot of glider videos on YouTube recently and
| it blows my mind that pilots can travel ~500km, even ~1000km with
| no propulsion, using only the lifting air.
|
| It would be a pretty good mode of transport if the general
| population could be trusted to responsibly and competently fly
| aircraft. Very low carbon.
| btreecat wrote:
| You should pay attention to the fatality rate for gliders. Some
| of the worst in maned aviation.
|
| It's considered 3-4x more dangerous than driving based on the
| annual fatality rate.
|
| Not that it isn't cool, it just won't become mainstream due to
| safety alone.
| croemer wrote:
| 3-4x more dangerous per what? Distance travelled, or time, or
| per year using average amounts that people drive/glide?
| croemer wrote:
| It's 50 times more dangerous than driving per hour:
| https://chessintheair.com/the-risk-of-dying-doing-what-we-
| lo...
| H8crilA wrote:
| You can fly even 3000km in a single day if you use lee waves,
| that's the world record. But gliding is really really far from
| being a viable transport, it's just a sport where you spend
| most of the time waiting for good weather. It's an
| exaggeration, but thinking that sailplanes could be used for
| commercial transport is almost like thinking that wave surfing
| could be used as such. We will sooner see some big return of
| airships than we will see commercial transport using gliders.
|
| As a sport it's absolutely breathtaking, it might be the best
| single thing that I've ever done. Please do mind the safety,
| though, it is not easy and it is not safe even though it may
| seem so after you've done your first ~hundred hours. It is a
| lot safer than paragliding because you'll crack the landing
| gear or the tail and not your spine on a bad landing.
| KineticLensman wrote:
| > It is a lot safer than paragliding because you'll crack the
| landing gear or the tail and not your spine on a bad landing
|
| Many years ago I did both skydiving and paragliding. For
| skydiving, in approx 70 jumps I had one slightly twisted
| ankle (which was actually an earlier injury that had weakened
| the ankle) and saw one situation where a jumper was
| stretchered away (they landed on their backside because they
| were trying to hit a target with outstretched legs. I also
| had a parachute malfunction and safely deployed my reserve.
| In paraglidimg, over a shorter timeframe, two people in the
| club received bad injuries (broken leg and broken hip) and
| another smashed their helmet in a collision with a dry-stone
| wall.
|
| The problem with paragliding seemed to be that canopies could
| collapse at very low altitude due to air turbulence (rotors)
| around the tops of hills where flights started and usually
| ended. In contrast, in parachuting from planes, there was
| 'plenty' of time to deal with parachute opening malfunctions
| (and to open reserves), and it was rare for canopies to then
| fail due to wind or terrain.
| sesm wrote:
| That's basically 'Nausicaa of the Valley of the Wind'
| CrazyCatDog wrote:
| The rc gliders are loaded chock-full with weight (tungsten or
| lead), we literally seek cover behind cars and boulders, and the
| bravest among us holds the radar speed gun---if you want to see
| something outside of this world, or spark your kids' imaginations
| as to the universe unlocked by the sciences--visit a DS site!
|
| P.S. bring ski goggles--you'll need them if the conditions are
| good, you won't see without them if it's a 400mph day--which is
| more and more common these days!
| mannykannot wrote:
| Ingo Renner (four times world gliding champion) reportedly
| demonstrated dynamic soaring in a human-carrying glider in
| 1977[1].
|
| Trying to do so in the boundary layer at ground level would be
| extremely dangerous, if at all possible, but Renner's insight was
| that there is sometimes an exploitable windshear at a safe
| altitude, on the boundary of an inversion.
|
| From the article: _" Renner has been attempting dynamic soaring
| for about four years, and the difficulties can be gauged from the
| fact that he has achieved only four really successful flights in
| that time."_
|
| [1] Flight International, 22 October 1977 reprinted here (PDF):
| https://www.sac.ca/index.php/en/free-flight-magazine-2/1970s...
| Maarten88 wrote:
| Those RC dynamic soaring gliders pull up to 80G, which might
| also be an indication that this is probably not a good fit with
| manned flight.
| consumer451 wrote:
| This concept may be applied to accelerating spacecraft.
|
| > Dynamic Soaring as a Means to Exceed the Solar Wind Speed
|
| https://arxiv.org/abs/2211.14643
|
| Related video:
|
| https://youtu.be/SkGRVvA23qI?t=799
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(page generated 2023-12-17 23:01 UTC)