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Mech_Engineer
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Here, this picture is twice as irrefutable
Another good one:
Another good one:
Just click the link - it runs in a browser.DaveC426913 said:I haven't downloaded the app to run it but those numbers confuse me - probably because I don't really know a lot about aerodynamics.
Yes - AoA is typically meausured geometrically, with the chord line going from the leading edge to the trailing edge. A cambered airfoil produces lift at zero (even slightly negative!) AoA.Why would an AoA of zero allow a plane to fly straight and level? I thought AoA always had to be +ive. Is that lift just due to the camber?
L/D is simply the ratio of lift to drag. If lift is positive, L/D is positive. A cambered airfoil can produce lift at negative AoA and the drag remains low because it's still not disturbing the air much with a pressure wake...Also, why does L/D go +ive while AoA is still -5, and why does L/D max out when AoA is still -ive?
Yes.I think I see. Because the wing has camber, it means that lift can begin increasing before drag does (since it's at AoA = 0).
Yes, and it may well be that a plane with this L/D flies at cruise speed at negative AoA - for efficient cruise flight, you'd want to design it that way. But note also that lift is a function of speed, so as speed drops, lift drops, so the AoA has to rise to keep the plane aloft.Seems to me, the conclusion to be had is that, to get the best L/D ratio, a plane's wings should actual have a slight negative AoA.
Yes, please. Have you people never been to an airshow?jarednjames said:A good point about number 5, but then surely it wouldn't fly so well right way up?
Let's stay in the realms of reality shall we.
I'm pretty sure you're goofing around. But in case you're not, what you propose isn't really a refutation. Your suggestion is less plausible and requires more hoops to jump through to make sense than merely the assumption that the pic is accurate.AlephZero said:Actually it's quite easy to "refute" that picture. This is the USAF "Thunderbirds" display team. If you look closely at the inverted aircraft, you will see the number "5" on the engine intake is also inverted (i.e. it is the right way up, in the picture). As the display commentators usually mention, that is because #5 spends pretty much the entire display flying upside down.
So prove to me that #5 isn't a specially built aircraft that is designed to ONLY fly upside down, and the "#5" that you see taking off and landing at the start of the display is just an "identical" decoy, to fool you. It is obvious that they wouldn't show you the secret military technology that let's the "real" #5 take off and land upside down, if that is the only way it can fly
(Or, there is a simpler explanation: both aircraft were actually flying vertically upwards, and somebody rotated the picture 90 degrees in photoshop).
I noticed that in the first pic, yes.russ_watters said:Also, something to note from that first Blue Angels pic (looking back, it is in the F-16 pic too...): it may just be an illusion of perspective, but the missile rail on plane 3 is clearly pointing slightly down
We all KNOW those pictures are rotated 90o!Mech_Engineer said:Here, this picture is twice as irrefutable
DaveC426913 said:I'm pretty sure you're goofing around.
AlephZero said:Indeed. That's what the "big grin" was for. I've already learned the hard way that humo(u)r isn't always an international language, though.
murphyr said:With respect to a wing, the air contacts the leading edge and follows the shape of the foil and continues downward as it leaves the trailing edge. Obviously, a steeper angle of attack and lowering of flaps causes the air to be forced downward at a much steeper angle, producing even greater lift but at the cost of increased drag. Therefore, it is Newton's Third Law, for every action there is an equal and opposite reaction, that creates lift.
murphyr said:Bernouli's Principal is why curve balls curve but not why airplanes fly.