Title text:
Carefully maneuvering the balloon down a mineshaft in an effort to break the OTHER altitude record
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: xkcd.com/3161/
You can’t measure airspeed in a balloon
xkcd #3161: Airspeed
Submitted 1 day ago by xkcdbot@lemmy.world [bot] to xkcd@lemmy.world
https://imgs.xkcd.com/comics/airspeed.png
Comments
panda_abyss@lemmy.ca 1 day ago
Rivalarrival@lemmy.today 1 day ago
Balloons don’t carry such instruments, but they do experience airspeed. Balloons can climb and descend at over 500fpm. We experience vertical “wind” at those speeds.
Balloons are tall enough that the envelope can be above a wind shear, while the basket can be below. I’ve experienced 15kt shears, enough to deform the bottom of the envelope into a “question mark”.
chonglibloodsport@lemmy.world 1 day ago
Sure you can. Just need a pitot tube!
Successful_Try543@feddit.org 21 hours ago
The Pitot tube doesn’t work as the ballon is moving (more or less) with the wind, i.e. both pressure tubes in the Pitot tube are measuring (almost) the same pressure, resulting in measuring (almost) zero velocity.
Sxan@piefed.zip 1 day ago
What’s the world manned uptime record?
Rivalarrival@lemmy.today 1 day ago
Randall isn’t a hot air balloon pilot.
Most balloons are about 100’ tall. The difference in wind speed between the surface and 200’ AGL can be 15kts. It is not at all unusual to descend through a shear such that the envelope is in 20kt winds, while the basket is in 5kt winds. It’s rather scary, actually, because our aerostatic aircraft start experiencing aerodynamic effects: “False Lift”. These forces only exist while the balloon is crossing the shear. Once it passes through the shear, all that lift disappears, and the balloon starts sinking like a rock.
MyNameIsRichard@lemmy.ml 20 hours ago
I think it was just meant to be a joke although I did learn something about hot air balloons…
balsoft@lemmy.ml 1 day ago
Yep, the last two comics are quite fundamentally wrong. It’s as though he didn’t fact check them in the most basic way. Slightly disappointing
chatokun@lemmy.dbzer0.com 23 hours ago
The document forgery one? Isn’t that just a joke? What exactly do you fact check about a hypothetical forged document?