Linked Questions

25 votes
5 answers
17k views

Is there a maximum lift to drag ratio?

If I recall correctly, the best competition gliders have a L/D ratio as high as 60:1. What imposes this limit? Is there a maximum theoretical L/D ratio, or could sufficiently advanced materials allow ...
raptortech97's user avatar
  • 5,128
16 votes
2 answers
18k views

What is the reason for the poor low-speed characteristics of sweptback wings?

I know there are advantages of swept-back wings delaying shock-wave allowing a aircraft to fly faster. However, what are the disadvantages. I know one of them is that they have very poor low speed ...
Harry Wang's user avatar
12 votes
4 answers
4k views

Why isn't there a single best airfoil for subsonic flight?

Why does airfoil used by modern subsonic aircraft (this is true for transonic airliners too) vary from plane to plane? Haven't we figured out a single best airfoil shape, with the highest lift to ...
Francis L.'s user avatar
  • 2,524
24 votes
2 answers
4k views

Is a golf ball surface a good idea for wings or fuselage?

I searched for an infamous golf ball question on this site but did not find any, so I guess it's time for one. Would a dimpled surface like a golf ball somehow improve the aerodynamics of an airplane?...
DrZ214's user avatar
  • 17.7k
17 votes
3 answers
3k views

Can the plane Celera 500L be eight times more fuel efficient than a jet of similar size and capacity?

Celera 500L (see Otto Aviation site for more details) is a plane with a single propeller powered by a piston diesel engine. The constructor claims it is 8 times more fuel efficient than a jet of about ...
Robert Werner's user avatar
15 votes
3 answers
4k 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 ...
Guy Inchbald's user avatar
  • 7,002
8 votes
1 answer
13k views

How does Reynolds Number affect skin friction drag?

I'm an aerospace engineering student, and I'm worried about efficiency as it relates to high and low Reynolds numbers. I don't understand which is more helpful for a aircraft. On a website I read ...
Volkan Aydıngül's user avatar
5 votes
2 answers
4k views

Does the Reynolds number on a smaller model need to match the one of the original aircraft?

1.Airbus 380-800 : The overall length of it , is 72.72 m and its cruise speed is 903 km/h. Based on the mean chord of wing , its Reynolds number in cruise phase is around 75 millions. Now , a 1/18 ...
alireza abbassi's user avatar
7 votes
1 answer
4k views

What is a laminar airfoil and what are their pros and cons?

I am wondering what is a laminar airfoil and what are their advantages and disadvantages if compared to other designs.
Konrad's user avatar
  • 1,963
13 votes
3 answers
828 views

How should we think of 'layers' of air flow?

Do a search for "boundary layer" or "laminar flow" on this site, and you'll find plenty of things to read. They'll talk about "the boundary layer", "flow separation" and so on, as though it were ...
Daniele Procida's user avatar
3 votes
3 answers
2k views

What is the relation between sweep angle and lift-to-drag ratio?

What is the relation between sweep angle and lift-to-drag ratio? And does it depend on the wing planform? For subsonic speeds.
user avatar
6 votes
2 answers
1k views

Why do wings prefer laminar flow if cd is lower for turbulent flows?

Can anyone please explain to me why we prefer to maintain laminar flow over wings, despite the fact that the overall coefficient of drag appears to reduce as the Reynolds Number increases? I have read ...
sroger13's user avatar
8 votes
1 answer
2k views

How do blow holes compare to other means of tripping the boundary layer?

The DG-300 glider has wing holes to delay flow separation. How do they compare to vortex generators and other means? This wing is 'blown' on the underside by 900 small holes to achieve a ...
user avatar
5 votes
1 answer
5k views

How is shear stress distributed on an airfoil?

I know the pressure distribution on an airfoil but not shear stress. How is shear stress distributed on an airfoil?
David Teahay's user avatar
  • 2,905
8 votes
1 answer
2k views

When should I use the global Reynolds number and when the local Reynolds number?

I know that for the wing, the Reynolds number is based on the MAC. This makes sense to me, as the boundary layer develops along the length of the wing. However, what kind of Reynolds number needs to ...
ROIMaison's user avatar
  • 7,127

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