How Aircraft Lift Works | profpilot.co.uk video #2

http://www.profpilot.co.uk | Trawling the murky depths of how gushing air over a couple of flatish metal surfaces can allow us to fling ourselves through the sky.
Episode 2 shows the principles behind how a wing works (thanks to Newton and Bernoulli), and how an aerofoil creates lift, which is quite a helpful force to have when it comes to aeroplanes.

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[g1geo1g]

I'm not being obtuse here my friend, the physics of fluids is thermodynamic. The energy is 'temperature' not pressure. Any model that assumes energy in a fluid is not related or significant to it's thermal properties is potentially lacking

[profpilotcouk]

@g1geo1g Hello again g1geo1g! Thanks for the continuing input. The reason why I left the thermal shenanigans to one side for this video was to provide enough information for PPL (and looking through my old textbooks now even ATPL) pilots to pass their ground exams, and also keeping it simple for a wider audience to appreciate. Anyone interested deeper in this topic than a five minute video should definitely check out some of the videos to the right. Although there may be fewer cats.

[g1geo1g]

That's a bit like saying that voltage and current vary the same, but it is true that the voltage drives the current, not vice versa. Also with fluids the energy is in the pressure and this pressure provides the energy for the flow by alignment of particle velocities from thermal 'noise'. The flow is a result of the former pressure.

[profpilotcouk]

@g1geo1g I did not know that. So there you are m1r3o; and thank you g1geo1g!

That was one weird sentence.

[m1r3o]

I've been reading that air speeds up because there's a decrease in pressure not the other way round.. can you explain me this?? It's sooo confusing!!!

[profpilotcouk]

@m1r3o Bonjourno m1r30! I am no great guru sensai deity sage of physics (contrary to appearance) so I could well be wrong, but if you look at 3:51 in the video, you'll see Bernoulli's exciting formula; from it you'll also see that one doesn't really lead on to the other - rather velocity and pressure change all at the same time. This would please the whole energy conservation thing that physicists like too.

[edwinmichaelquiboloy]

i wish my instructor would be hilarious like this

[PiranaArana]

Thanks you so much for these easy to understand informative videos. Now I can get up every morning without the haunting fear of not knowing how things fly. Thank you.

[gokharol]

I really like airplanes but Im not sure about becoming a pilot, well have you seen any girls around on a plane? :P

[shebotnov]

@g1geo1g yep, there is no such thing as "temperature" in physics.

[g1geo1g]

I do concede sir, and agree that within the context, my criticism is unnecessary. It is however of great interest to me and perhaps to some others that the simple model for the description of lift, although accepted and taught, is as much correct as incorrect!

[g1geo1g]

And that's where it all goes 'pear shaped', because energy is not conserved, flow decreased and pressure decreased? But if we involve temperature then all can be resolved! We've just invented a refrigerator!

[g1geo1g]

Some of the problems lie within the model itself. For instance, having someone sit on your pipes potentially increases the pressure before the constriction, and that pressure 'forces' the flow. However, even after the release of the constriction the former pressure is never attained because flow always is 'down' a pressure gradient.