Mortgage question

[KenP]

Originally Posted by CO Hummer

Clearly they need some training. I mean, if you look at that pic you'll see that many factors contribute to the total lift produced by an airfoil. Increased speed causes increased lift because a larger pressure differential is produced between the upper and lower surfaces. Lift does not increase in direct proportion to speed, but varies as the square of the speed. Thus, a blade traveling at 500 knots has four times the lift of the same blade traveling at only 250 knots. Lift also varies with the area of the blade. A blade area of 100 square feet will produce twice as much lift as a blade area of only 50 square feet. Angle of attack also has an effect on the lift produced. Lift increases as the angle of attack increases up to the stalling angle of attack. Stall angle varies with different blades and is the point at which airflow no longer follows the camber of the blade smoothly. Air density is another factor that directly influences lift.

Unfortunately, there is no simple equation to compute the lift generated by a helicopter rotor in hover like there is for forward flight. Instead, we must rely on substantially more complicated methods like the Blade Element Momentum Theory or the Actuator Disk Vortex Theory. Both approaches involve complex jargon and even more complex mathematics that would require far more explanation than we have the time or space to discuss here (to emphasize the point, I have a 1,000 page book on the subject of helicopter theory!). In either case, we are not concerned with computing the lift so much as we are the power required to maintain hover and the thrust force generated by the rotor.

Air being accelerated through a hovering rotor In order to generate this thrust, the rotor pulls air down through it, as illustrated above, acting just like an airplane propeller that has been turned 90?. The spinning rotor accelerates the air as it goes through the rotor disk creating a force that acts in the opposite direction. This upward force is the rotor thrust. If you think about it, since this "thrust" points straight up and is the only force counteracting the weight of the helicopter, this force is the lift.

[K9sH3]

they have added a new driving light up front and can see in the dark.