Lecture 9 Flashcards
Draw the different envelopes of unsteady waves (Mach cone) when flying at different Mach numers
Slide 6
Draw the waves and the evolution of u and cp over a flat plate, when it has an Angle of Attack
Also the forces
Does this configuration lead to Lift?
Does this configuration lead to Drag?
Slide 13
It does contribute to Lift
It does produce Drag
Draw the waves and the evolution of u and cp over a plate with chamber
Also the forces
Does this configuration lead to Lift?
Does this configuration lead to Drag?
Slide 18
It does not contribute to Lift. It turns the object
It does produce Drag
Draw the waves and the evolution of u and cp over a symmetric object with thickness
Also the forces
Does this configuration lead to Lift?
Does this configuration lead to Drag?
Slide 23
It does not produce Lift
It does produce Drag
Table of differences between thickness, AoA and camber in Supersonic and Subsonic flows for Lift and Drag
Slide
State D’Alembert’s paradox
2D inviscid, subsonic, steady flow
Lift is possible
Drag = 0
What is „wave drag“?
Drag caused by waves, typically due to the losses in shock waves. In linear theory we don’t have shock waves, but we still have resultante force due to pressure in flow direction (Drag)
This is the wave drag
Can this „wave drag“ be negative?
No
It would mean being possible accelerating the fluid without limit.
Does a flat, cambered airfoil make sense for supersonic flight?
No
The thickness is causing Drag. The camber is causing Drag
However, none of the, are causing Lift
How can one generate lift in supersonic flight?
The only possible way is with angulation (Angle of Attack)
Is for M>1 lift without drag possible?
No
The only mechanism causing Lift is angulation, and it also generates Drag
