Physics of flight?

In the past I’ve had some “how do airplanes fly” type of topics. In particular one such topic starting with a table of the IF 787’s tradeoffs between weight, AoA, and IAS vs TAS (as represented by Mach number) considered the question, how are those relationships we experience in IF related to irl physics?

Just a quick update on an aspect of that. I had criticized Neil Degrass Tyson’s explanation of lift (though, to be fair, not only his). But who am I to do that against a celebrity astrophysicist(?).

I just thought the following was an interesting recent update on that from an aviation youtuber. The following criticism sure caught my attention:

edit: A mild rant: From the “equal transit time fallacy” to the “you don’t need the Coanda effect to explain lift” and everything in between, I’m going to suggest that fact checking of all these experts debating each other, should rest on the fundamental laws and linked relationships in the Navier-Stokes equations.

While we don’t need to perfectly solve these, being some of the world’s most challenging simultaneous partial differential equations, we can take a glance at the underlying physics of those Newtonian based laws of the real world, an interconnected description of such reliability that it is the basis of all the irl aircraft manufacturer computer modelling (the best numerical simulation methods of Navier-Stokes gives results that approach real world physical tests for the forces and flows around an airfoil).

Example: What does this Youtuber get half right and half wrong, in responding to what Degrasse Tyson gets half right and half wrong, that also the referenced Cambridge professor gets half right and half wrong (at least in his presented wording)?: How to clear the mess of the “equal transit time fallacy” and statements such as: “it doesn’t speed up just because the upper surface is curved?”

Referring to Navier-Stokes, the “equal transit time fallacy” is just an oversimplification of the mass flow rate continuity equation (one of the few necessary physical laws tied together in those equations).

Fact checking idea: seek the highest standard of information at our disposal.

Why in IF our A380, B787 etc. tilt up more at higher altitude, especially when heavily loaded, and fall out of the sky when we continue yet higher? Because we need (and sometimes exceed) enough pressure drop, forced by the law of mass flow continuity (substitute for equal transit time), to curve adjacent passing air enough (Newton’s action reaction law), to overcome our weight. The tilt compliments camber in stressing the relative wind sufficiently. Navier Stokes gives discipline to explanations of those fundamental, known and tested, relationships.

9 Likes

This is cool but what does it have to do with infinite flight

Connecting the separate pieces. There are periodically questions: why is my aircraft tilted so much? Why do I fall out of the sky? Why do I pitch up more when the flaps are not lowered? So part of it is personal. Do I really have some grasp of how the pieces fit together when I try to formulate an answer?

I use IF to connect my own particular separate experiences in aviation. The dividing line is not always clear.

Because I had previously developed a flight simulator (on older hardware) from the ground up to fully functional, it’s how I think about it when I’m flying in IF. Often thinking, how does the representation I experience in IF connect with the challenge I had to face in getting something up and running that felt like when I had learned to fly (back before ever touching a simulator).

There is also the community history element.

4 Likes