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: https://xkcd.com/3161/
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: https://xkcd.com/3161/
You can’t measure airspeed in a balloon
You can, it’s just usually zero, which is what I think the comic is suggesting
What if they ascended to normal altitude, then lowered a tether back down to the ground? Probably break some records as the wind swung you down to the ground.
I don’t think that would be level-flight
Tether yourself on three sufficiently far apart points with no slack in the rope, and you will be stationary
It would be wind speed wouldn’t it.
Airspeed of hot air balloons would be very similar to wind speed, except for when there’s a quick change in wind speed as the balloon would have some momentum
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”.
On most flights, pilots will experience 5-7kt shears at certain times.
Sure you can. Just need a pitot tube!
The Pitot tube doesn’t work as the ballon is moving (more or less) with the wind, i.e. both pressure tubes, the one for static pressure and the one for total pressure, in the Pitot tube experience (almost) the same pressure, resulting in measuring (almost) zero dynamic pressure and thus velocity.
It records an air speed of 0. Isn’t that working exactly as intended?
Isn’t one usually interested in the speed relative to the ground?
No. The comic is talking about airspeed: speed relative to the wind.
Ah, ok. I somehow got that wrong.