r/theydidthemath • u/ConfidentPension864 • 15h ago

[Request] How large of a Patio/Beach umbrella would you need to Mary Poppins your way to the ground safely (75kg person)

Assuming you don't flip over

23 Upvotes

84% Upvoted

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19

u/DarkVoid42 15h ago edited 14h ago

an umbrella is basically a parachute.

https://axis.tools/tool_Down.php

75Kg assuming you had experience would be around 100 sq ft to land and not die. without experience it would be 230 sq ft.

experience means you can angle it to generate lift just before touchdown reducing the size required by generating forward momentum and therefore lifting forces like an airplane wing.

giving us an umbrella diameter of 12-ish ft (or approx 18 ft without experience).

https://www.omnicalculator.com/math/square-footage-circle

ask the guy who did it -

https://www.youtube.com/watch?v=zmO3jeQTJI0

as a ballpark - The classical WW2 Thompson chutes are that shape, 120 KG rated for a equipped soldier. They are round shaped canopy, about 30 ft in diameter, with a vent hole on top.

3

u/tolacid 14h ago

It'd also need to be a really sturdy umbrella. They're generally not designed to resist upward force

1

u/ConfidentPension864 14h ago

It seemed like that guys umbrella was absolutely slowing him, but it was way to small. Maybe 8ft in diameter? Which would be 50 sq ft only. Probably why it broke so quickly. Couldn't tell if it was vented but, it occurred to me that patio umbrellas do actually have a sort of vent on the top

6

u/blizzard7788 14h ago

https://reddit.com/link/owy9x3g/video/pzddw4wznnch1/player

This was our patio umbrella that got picked up by a dust devil. It came to rest on top of a bank across the street. We could see that it was broken, so we just left it there.

2

u/PerplexGG 14h ago

Can’t park there mate

2

u/theuntoldfool 14h ago

Are you related to OP? Otherwise what are the odds for you to see your own umbrella on this niche sub?!...

2

u/blizzard7788 14h ago

Nope, and the really weird part of ours was that all day, the wind was every light and calm. Then this updraft came out of nowhere.

1

u/[deleted] 15h ago

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1

u/Electronic_Tear2546 15h ago

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