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For example, the NACA 2412 airfoil has a maximum camber of 2% located 40% (0.4 chords) from the leading edge with a maximum thickness of 12% of the chord. The NACA 0015 airfoil is symmetrical, the 00 indicating that it has no camber. The 15 indicates that the airfoil has a 15% thickness to chord length ratio: it is 15% as thick as it is long.
For any given value of lift, the AoA varies with speed. Graphs of C L and C D vs. speed are referred to as drag curves. Speed is shown increasing from left to right. The lift/drag ratio is given by the slope from the origin to some point on the curve and so the maximum L/D ratio does not occur at the point of least drag coefficient, the ...
Drag and lift coefficients for the NACA 63 3 618 airfoil. Full curves are lift, dashed drag; red curves have R e = 3·10 6, blue 9·10 6. Coefficients of lift and drag against angle of attack. Curve showing induced drag, parasitic drag and total drag as a function of airspeed. Drag curve for the NACA 63 3 618 airfoil, colour-coded as opposite plot.
In February 1976, work commenced to automate the methods contained in the USAF Stability and Control DATCOM, specifically those contained in sections 4, 5, 6 and 7.The work was performed by the McDonnell Douglas Corporation under contract with the United States Air Force in conjunction with engineers at the Air Force Flight Dynamics Laboratory in Wright-Patterson Air Force Base.
NACA experience provided a model for World War II research, the postwar government laboratories, and NACA's successor, the National Aeronautics and Space Administration (NASA). NACA also participated in development of the first aircraft to fly to the "edge of space", North American's X-15. NACA airfoils are still used on modern aircraft.
An angle of attack limiter or an "alpha limiter" is a flight computer that automatically prevents pilot input from causing the plane to rise over the stall angle. Some alpha limiters can be disabled by the pilot. Stall warning systems often involve inputs from a broad range of sensors and systems to include a dedicated angle of attack sensor.
Prior submerged inlet experiments showed poor pressure recovery due to the slow-moving boundary layer entering the inlet. The NACA design is believed to work because the combination of the gentle ramp angle and the curvature profile of the walls creates counter-rotating vortices which deflect the boundary layer away from the inlet and draws in the faster moving air, while avoiding the form ...
The NACA cowling enhanced speed through drag reduction while improving engine cooling. The cowling consists of a symmetric, circular airfoil that is wrapped around the engine. In a normal planar airfoil, like a wing, the difference in airspeeds, and their associated changes in pressure, on the top and bottom surfaces, enhances lift.