Where did the false "equal transit-time" explanation of lift originate from?

Re:Where did the false "equal transit-time" explanation of l... by marcus_holmes on Wednesday April 23, 2025 @02:57AM (#43769362)

I recently encountered this in a sailing class when the teacher was explaining how "pull-mode" works in sailing, where the wind is coming from ahead of the vessel and pulls the sails rather than pushing them. I knew this theory to be debunked and yet couldn't work out the answer from non-debunked physics (and certainly didn't want to disrupt the class by arguing physics with someone who's been sailing for 50+ years - if it worked for him, it'll probably work for me, even if debunked).

Modern sailing vessels always sail into the wind, because they're always going faster than the wind blows. I do find the physics of this fascinating.

[ Parent | on HN ]

Re:Where did the false "equal transit-time" explanation of l... by crooked-v on Wednesday April 23, 2025 @03:23AM (#43769498)

Sailboats that sail into the wind are also a bit different than planes because it's the boat being "pinched" between the wind-caused lift and the counteracting force from the water that provides the forward propulsion. It's analogous to something slippery shooting out from between two hands if you squeeze it.

[ Parent | on HN ]

Re:Where did the false "equal transit-time" explanation of l... by kuhewa on Wednesday April 23, 2025 @03:48AM (#43769630)

> Modern sailing vessels always sail into the wind, because they're always going faster than the wind blows.

Maybe state of the art hydrofoiling boats, cats and some quite large monohulls, but maybe that's what you meant by modern. Most sailboats built today have a pretty low top speed (due to hull speed limitations) relative to wind speed - monohulls often max out around 5-6 kts aren't going to be faster than the wind pretty much ever

[ Parent | on HN ]

Re:Where did the false "equal transit-time" explanation of l... by marcus_holmes on Wednesday April 23, 2025 @03:58AM (#43769681)

yeah, sorry, I should have specified modern racing sailing vessels

[ Parent | on HN ]

Re:Where did the false "equal transit-time" explanation of l... by throwaway290 on Wednesday April 23, 2025 @04:15AM (#43769751)

Is it debunked or just renamed from "pull" to "lift"? Lift much more confusing when you think of a boat instead of a plane so "pull mode" probably works better in practice. Since no one has a full understanding of lift you're probably fine...

[ Parent | on HN ]

Re:Where did the false "equal transit-time" explanation of l... by jabl on Wednesday April 23, 2025 @03:14AM (#43769452)

For the physics of sailing see http://gentrysailing.com/pdf-theory/A-Review-of-Modern-Sail-...

[ Parent | on HN ]