JoshTheEngineer | Explained: Supercritical Airfoil [Airplanes] @JoshTheEngineer | Uploaded July 2013 | Updated October 2024, 38 minutes ago.
At transonic speeds, shocks waves form on the wings of an aircraft. Wave drag due to the presence of shocks can become a large portion of the overall drag on the aircraft. A supercritical airfoil can be used to delay the onset of shocks, and thus enable faster cruising speeds.
If you would like some more background on the subject, feel free to watch the following videos.
goo.gl/hCKHgf
goo.gl/iFxmXs
There are a couple things I want to mention briefly regarding drag. I mentioned the critical Mach number in the video, but neglected to include the drag divergence Mach number. Nothing particularly special happens at the critical Mach number. The shock wave or pressure wave that is formed is actually fairly weak because the flow doesn’t need to slow down too much through the shock wave. There is, however, a freestream Mach number at which the drag starts to "suddenly" increase quite a bit. This Mach number is the drag divergence Mach number, and is actually more important than the critical Mach number when designing planes. Wave drag occurs due to the presence of shock waves, and as the Mach number increases, wave drag also increases. If you’d like to read some more about the drag divergence Mach number, here are some references to get you started.
"Modern Compressible Flow," John D. Anderson, pg. 345
en.wikipedia.org/wiki/Drag_divergence_Mach_number
http://www.adl.gatech.edu/research/extrovert/classes/hispd/hispd_notes06.pdf
http://adg.stanford.edu/aa241/drag/cdcintro.html
naca.central.cranfield.ac.uk/reports/1947/naca-tn-1396.pdf (pg. 6 under Drag Characteristics)
At transonic speeds, shocks waves form on the wings of an aircraft. Wave drag due to the presence of shocks can become a large portion of the overall drag on the aircraft. A supercritical airfoil can be used to delay the onset of shocks, and thus enable faster cruising speeds.
If you would like some more background on the subject, feel free to watch the following videos.
goo.gl/hCKHgf
goo.gl/iFxmXs
There are a couple things I want to mention briefly regarding drag. I mentioned the critical Mach number in the video, but neglected to include the drag divergence Mach number. Nothing particularly special happens at the critical Mach number. The shock wave or pressure wave that is formed is actually fairly weak because the flow doesn’t need to slow down too much through the shock wave. There is, however, a freestream Mach number at which the drag starts to "suddenly" increase quite a bit. This Mach number is the drag divergence Mach number, and is actually more important than the critical Mach number when designing planes. Wave drag occurs due to the presence of shock waves, and as the Mach number increases, wave drag also increases. If you’d like to read some more about the drag divergence Mach number, here are some references to get you started.
"Modern Compressible Flow," John D. Anderson, pg. 345
en.wikipedia.org/wiki/Drag_divergence_Mach_number
http://www.adl.gatech.edu/research/extrovert/classes/hispd/hispd_notes06.pdf
http://adg.stanford.edu/aa241/drag/cdcintro.html
naca.central.cranfield.ac.uk/reports/1947/naca-tn-1396.pdf (pg. 6 under Drag Characteristics)