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I admit of not being able to understand this: >>>because the engine nacelles were so far in front of the wing and so large, a power increase will cause them to

I admit of not being able to understand this: >>>because the engine nacelles were so far in front of the wing and so large, a power increase will cause them to actually produce lift, I thought that it would make the plane "tilt" upwards, but the quote mentions "lift". Does this happen because the engines, being in front of the wing and as well very near to it are "sucking" air that would otherwise flow as well >>over<< the wing, therefore creating a lower-than-usual pressure above the wing, therefore making the airplane climb/generate lift?

mannykannot 7y ago
It has nothing to do with power. Even cylindrical bodies produce some lift when their axis is not aligned with the airflow, and all engine nacelles do this. If they are forward of the CofG, this produces a pitch-up moment that increases with increasing angle of attack, and therefore reduces stability. The further forward they are, the more the leverage and the stronger the effect. With rear mounted engines, the effect produces a nose-down moment, which contributes to the longitudinal stability. See the links in my other post: https://news.ycombinator.com/item?id=19904685 https://news.ycombinator.com/item?id=19904685
salawat 7y ago
A good way to visualize it, I've found, is imagine the low pressure area created by the wing as a bubble attached to the aircraft, "sucking" the aircraft up. Imagine the air going under the wing as analogous to the surface of a lake. The more the plane diverges from parallel to the airstream, the stronger the tendency for the bubble to suck through the "shadow" created in the airstream, and the plane to "skip" on the surface (the air getting pushed under the airfoil). In reality, these are two different ways of illustrating the same force. This visualization though, let's you pick out two different aspects. Air is a fluid. Just like water will follow the edge of a pan when you pour it, the curvature of an airfoil does the same thing with air flowing by. Those nacelles basically enhance the surface area across which that pressure differential acts through. In short, generating extra lift, "pulling" the plane up more, (or pushing, if you prefer looking at it from the skipping stone aspect) creating more lift, all the way into a stall condition.
- zepearl 7y ago
  Thx!

mannykannot 7y ago

It has nothing to do with power. Even cylindrical bodies produce some lift when their axis is not aligned with the airflow, and all engine nacelles do this. If they are forward of the CofG, this produces a pitch-up moment that increases with increasing angle of attack, and therefore reduces stability. The further forward they are, the more the leverage and the stronger the effect. With rear mounted engines, the effect produces a nose-down moment, which contributes to the longitudinal stability. See the links in my other post: https://news.ycombinator.com/item?id=19904685 https://news.ycombinator.com/item?id=19904685

salawat 7y ago

A good way to visualize it, I've found, is imagine the low pressure area created by the wing as a bubble attached to the aircraft, "sucking" the aircraft up. Imagine the air going under the wing as analogous to the surface of a lake. The more the plane diverges from parallel to the airstream, the stronger the tendency for the bubble to suck through the "shadow" created in the airstream, and the plane to "skip" on the surface (the air getting pushed under the airfoil). In reality, these are two different ways of illustrating the same force. This visualization though, let's you pick out two different aspects. Air is a fluid. Just like water will follow the edge of a pan when you pour it, the curvature of an airfoil does the same thing with air flowing by. Those nacelles basically enhance the surface area across which that pressure differential acts through. In short, generating extra lift, "pulling" the plane up more, (or pushing, if you prefer looking at it from the skipping stone aspect) creating more lift, all the way into a stall condition.

zepearl 7y ago
Thx!