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Author Topic:   Physics of Flight
JustinC
Member (Idle past 4844 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 1 of 2 (565290)
06-15-2010 8:44 PM


I don't know if anyone here has looked into flight physics, but it seems much more complicated than the classic explanation would lead you to believe.
The classic explanation of flight involves Bernoulli's principle, which states that the faster a fluid is moving, the less pressure that fluid will exert on its surroundings. The wing of an aeroplane is curved so that, in cross section, that top is longer than the bottom. The air stream splits at the leading edge of the wing and meets back at the trailing end. Since the top air stream travels a further distance in the same amount of time, it must be traveling faster. Therefore, according to Bernoulli's principle, it exerts less pressure than the bottom and lift is generated.
This explanation is very problematic on logical and empirical grounds. 1. There seems to be no reason the air streams would have to meet at the same time after they split, and 2. They empirically don't; the top stream travels much faster than predicted by the model.
The other explanation involved Newton's third law. The wing is angled slightly upward as it is accelerated into the air. The air collides with the bottom of the wing and is deflected downward. The collision causes the wing to be pushed upwards.
This is also problematic because it neglects the top of the wing. I also don't think the math works out, i.e., you could generate enough lift if this were the sole mechanism.
So how do aeroplanes fly? My educated guess:
The bottom of the wing is moving towards the air, which is being deflecting downward. Just as the Newtonian model would explain it. But, in addition, the top of the wing is moving away from the adjacent air. This would create a partial vacuum, i.e., less pressure.
So, in effect, there is pressure being built up on the bottom and pressure being removed from the top. These effect combined explain lift.
Probably not, but that's the best I can do. Any input would be greatly appreciated.
Also, any insight into the physics of flapping wings would be appreciated. I found this website: How Birds & Ornithopters Fly.
It seems to explain alot of the physics, but I'm not sure if its correct.
Edited by JustinC, : No reason given.

Replies to this message:
 Message 2 by Adminnemooseus, posted 08-13-2010 7:33 PM JustinC has not replied

Adminnemooseus
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Posts: 3974
Joined: 09-26-2002


Message 2 of 2 (574064)
08-13-2010 7:33 PM
Reply to: Message 1 by JustinC
06-15-2010 8:44 PM


From deep in the PNT pile
For whatever reason, this proposed new topic (PNT) got ignored.
Not that it stops other topics, but I think a discussion of flight physics is pretty remote to the EvC core. I'm going to reject and close this one.
Opinion to the contrary? Post at the "Topic Proposal Issues" topic, link in the "signature" below.
Adminnemooseus

New Members should start HERE to get an understanding of what makes great posts.
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It really helps moderators figure out if a topic is disintegrating because of general misbehavior versus someone in particular if the originally non-misbehaving members kept it that way. When everyone is prickly and argumentative and off-topic and personal then it's just too difficult to tell. We have neither infinite time to untie the Gordian knot, nor the wisdom of Solomon.
There used to be a comedian who presented his ideas for a better world, and one of them was to arm everyone on the highway with little rubber dart guns. Every time you see a driver doing something stupid, you fire a little dart at his car. When a state trooper sees someone driving down the highway with a bunch of darts all over his car he pulls him over for being an idiot.
Please make it easy to tell you apart from the idiots. Message 150

This message is a reply to:
 Message 1 by JustinC, posted 06-15-2010 8:44 PM JustinC has not replied

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