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A comment on Andean condor can fly for 100 miles without flapping wings. Parent comment

Re:Andean condor can fly for 100 miles without flapping wings by jillesvangurp on Tuesday July 14, 2020 @07:12AM (#23830534)
Neal Stephenson's Seveneves has a part (part 3) of the book that is set in the distant future. One plot point there is some kind of advanced glider basically exploiting the atmosphere to pick up enough energy over the course of a day to eventually get enough mass (by picking up water) and energy to eventually travel at high speeds & altitudes half way across the planet. Science fiction of course but he has a way of making this somewhat plausible.

Gliders sometimes use water ballast to store more energy so they can stay up longer. Basically after getting towed to an initial altitude they use thermals and ridge soaring to gain altitude. After that it's all about converting altitude to speed and distance based on their glide ratio. Having a high mass apparently helps. Hopping from one lift producing area to another, you can cover great distances.

Currently this is pretty much a recreational activity because you are dependent on weather, sunlight, and other things that are hard to predict and detect. But kind of intriguing notion what you could do if you had a way to reliably find areas with good lift.

On a related note, here's a youtube channel of a glider pilot in Kansas that regularly posts awesome footage from his glider. Here's some awesome footage of him exploring some mountains and exploiting available lift from winds hitting the rocks: https://www.youtube.com/watch?v=Bcd5Z46RGRU

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Re:Andean condor can fly for 100 miles without flapping wings by samvher on Tuesday July 14, 2020 @09:20AM (#23831579)
The point about water ballast is actually not entirely accurate - it's not to stay up longer, it's to increase speed. Gliders have a certain angle of attack at which they fly most efficiently (optimal glide angle, i.e. trading the least height for every meter forward). If you add water ballast, the speed corresponding to that angle of attack is increased. The downside is that your downward speed also increases - so when the weather gets difficult or thermals get weak, pilots dump the water.
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Re:Andean condor can fly for 100 miles without flapping wings by eloff on Tuesday July 14, 2020 @01:04PM (#23834574)
> The downside is that your downward speed also increases

You're saying the down component of the velocity vector also increases with the velocity itself. Not that heavier objects fall faster, which we know to be untrue from Galileo's famous experiment. I think you understand that, but I thought I'd clarify it.

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Re:Andean condor can fly for 100 miles without flapping wings by platypii on Wednesday July 15, 2020 @11:45AM (#23846890)
No you're wrong. Galileo's experiment doesn't apply here. Heavier objects DO fall faster at terminal velocity. A glider in sustained flight is an example of that.

Galileo just showed that objects accelerate at the same rate due to gravity. But they do NOT fall at the same rate unless in a vacuum.

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Re:Andean condor can fly for 100 miles without flapping wings by eloff on Wednesday July 15, 2020 @02:45PM (#23849775)
You're right, I didn't think about the difference in terminal velocity.
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Re:Andean condor can fly for 100 miles without flapping wings by meheleventyone on Tuesday July 14, 2020 @08:21AM (#23830991)
If you want to play about with gliders yourself the sim Condor Soaring is pretty awesome and has VR support. It's a much more chill and relaxing experience than flying combat sims all the time and more engaging than most non-combat sims.
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