Generating lift at supersonic speeds

In summary, the generation of lift at supersonic speeds is different from that at subsonic speeds due to reduced viscous effects and the unsuitability of normal airfoils for such applications. Despite extensive research, there is limited information on the fluid mechanics involved in generating lift at supersonic speeds. However, it is known that at supersonic speeds, drag is the main concern and angle of attack plays a crucial role in generating lift. This is achieved by creating a high pressure below the wing through an oblique shock and a lower pressure above via Prandtl-Meyer expansions. However, this is a simplified explanation as real supersonic aircraft have highly swept wings and require a shape that is effective at both supersonic and subsonic
  • #1
flirt
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Im having some trouble understanding how lift is generated at supersonic speed as apposed to subsonic speed. Viscous effects at high speed are greatly reduced and a normal airfoil from subsonic flight is not suitable for such applications.
I have had a good read on wiki and other sites but i can't find much regarding the fluid mechanics of it. I would think there would be a lot on this subject, so how is this lift being generated?
 
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  • #2
if the wing hits the air at an angle then the air never knows that the wing is supersonic
 
  • #3
I want to know too. Where are the forces on the wing?
 
  • #4
Lift is generated more or less the same way - drag is the big issue at supersonic speeds. Drag is why you make diamond shaped wings instead of round wings for supersonic flight.
 
  • #5
At supersonic speeds, camber no longer affects lift and angle of attack becomes the most important factor. You generate a high pressure below the foil with an oblique shock and the lower pressure above via Prandtl-Meyer expansions. Of course that is an oversimplification because a real supersonic aircraft would have highly swept wings and needs to have a shape that works both supersonically and subsonically.
 

1. How does lift work at supersonic speeds?

At supersonic speeds, lift is generated by the pressure difference between the upper and lower surfaces of an airfoil. This pressure difference is created by the compression of air molecules as they flow over the curved surface of the airfoil. The faster the airfoil moves, the higher the pressure difference and therefore the greater the lift.

2. What is the role of shock waves in generating lift at supersonic speeds?

Shock waves play a crucial role in generating lift at supersonic speeds. As the airfoil moves through the air, shock waves form at the leading edge and along the upper surface. These shock waves help to compress the air and create the necessary pressure difference for lift to be generated.

3. How does the shape of an airfoil affect lift at supersonic speeds?

The shape of an airfoil is critical in generating lift at supersonic speeds. A thinner and more curved airfoil is more efficient at creating the necessary pressure difference for lift. Additionally, certain airfoil shapes, such as the diamond or wedge shape, are specifically designed for supersonic flight and can generate more lift compared to traditional airfoil shapes.

4. What is the impact of angle of attack on lift at supersonic speeds?

The angle of attack, or the angle at which the airfoil meets the oncoming air, has a significant impact on lift at supersonic speeds. A higher angle of attack can increase the lift generated, but if the angle is too high, it can also lead to shock waves forming too early and decreasing lift. It is important to find the optimal angle of attack for a given airfoil and speed to maximize lift.

5. Can supersonic lift be generated without an airfoil?

While airfoils are the most common method of generating lift at supersonic speeds, they are not the only way. Wingless vehicles, such as supersonic rockets, use the shape of the rocket to generate lift and control their flight. Additionally, some supersonic vehicles use a combination of airfoils and control surfaces to generate lift and maneuver at high speeds.

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