4 ms·

Something really bugs me about this. Unless I'm mistaken, Bernoulli's principle doesn't say anything about throwing air down .... http://en.wikipedia.org/wiki

• Someone 14y ago
  Read that second page, specifically the "Overall air direction is changed to go down" in the last two pictures. You can also see this from conservation of momentum; it requires that, if something goes up, something else must come down. With an entire airplane going up, there isn't much else than air to come down (exhaust gases are another option, but then, you are talking rocket, not airplane). And yes, gravity means the (airplane plus surrounding air) system isn't closed, but its effects only make matters worse; airplanes have to throw down air even to maintain level flight.