Linked Questions

16
votes
2answers
8k views

What is the significance of the speed of sound to aerodynamics and aircraft design?

Almost every aspect of flight seems to be affected by the speed of sound, somewhat in the same way that nearly everything in physics is determined by the speed of light. Obviously it's not exactly ...
11
votes
4answers
4k views

Why do airfoil's trailing edges point downward?

The trailing edge of and airfoil is mostly pointing downward. Is there any reason for that? Down wash increases drag and down wash is due to the direction of air pointing down. If the trailing edge is ...
21
votes
1answer
21k views

Accelerated Stall, what is it, how do you prevent it?

I've read a lot of NTSB crash reports regarding small, GA aircraft (just trying to figure out what went wrong and what to avoid.) There seem to be a lot of reports that talk about "low altitude high ...
13
votes
3answers
2k views

What is the difference between flow separation and turbulent flow?

For air flowing over a wing, both flow separation and turbulent flow involve disturbed flow next to the surface and smooth flow further away. At what point does one say "oh, this flow has changed ...
16
votes
4answers
4k views

Why are swept wings better for breaking the sound barrier?

I'm told that swept wings perform better when an aircraft is trying to break the sound barrier. I was wondering why that would be?
11
votes
2answers
57k views

What are the advantages and disadvantages of a delta wing compared to a swept wing?

What advantage does a delta wing have over a swept wing with high AR for supersonic flight? And what disadvantage does a delta wing have over a swept wing with high AR for transonic flight? The ...
8
votes
4answers
14k views

Where is the spanwise flow? How does the span wise flow point the air towards the wingtip?

If you search Google for span wise flow, the first result under the pictures tab is a image of a wing with the span wise flow at the trailing edge: (Source) If you look at some other photos you ...
10
votes
3answers
3k views

How is the area rule applied on airliners like the A380?

Wikipedia says that because of the area rule's impact on wave drag: aircraft have to be carefully arranged so that at the location of the wing, the fuselage is narrowed or "waisted", so that the ...
10
votes
2answers
2k views

How would an airfoil react if it was flown backwards?

Out of curiosity what would happen? Would pressure on both top and bottom flip? or stay the same or act as a normal wing with less lift? I'd assume it would still take longer to travel over the top ...
5
votes
4answers
1k views

What is the fundamental physics behind L/D decreasing as AoA increases beyond the optimal point?

Why does lift over drag decrease with AoA past the optimum AoA? Is it because the backwards vector for a given lift force on the wing is now larger for a given air particle compared to lower AoA? ...
9
votes
2answers
2k views

What causes the reduction in speed across the shockwave?

Wherever I read about shock waves, it is mentioned that there is a reduction in speed across the shock wave. Can someone please explain what happens at the molecular level, i.e. the physics of the ...
6
votes
5answers
3k views

What happens during a powered descent?

I was having a discussion with my friend about equilibrium condition in flight: Scenario: While going in straight and level flight, say I reduced my airspeed by 30 mph. At the same time keeping the ...
4
votes
5answers
3k views

What is the relation between the boundary layer and lift of an aerofoil?

Why do we try to reduce the thickness of the boundary layer over an aerofoil as much as possible if the boundary layer is responsible for creating lift?
10
votes
2answers
3k views

What are the pros/cons of all-moving rudder?

All-moving flight control surface (stabilator instead of a stabilisator+elevator) are common on supersonic aircrafts but this is usually used for pitch control only. For rudder, this design (one all-...
4
votes
1answer
13k views

What is the effect of airfoil thickness on aerodynamic lift?

More than once I`ve read that the airfoil thickness contributes little to the lift compared to the angle of attack and airfoil curvature and has more to do with airfoil stall characteristics. Could ...

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