Linked Questions

32
votes
9answers
8k views

Why are dirt and bugs on an aircraft so bad?

It's noted in many POHs to keep your aircraft clean all the time, but is there a reason to this? Dirt hardly add any sort of weight to the aircraft, bugs are extremely small and other things such as ...
39
votes
4answers
7k views

What does the behaviour of water on the skin of an aircraft in flight tell us?

Sometimes in damp conditions I notice some surprising (surprising to me, anyway) behaviour of water. I'll see moisture glistening in the heads of rivets or bolts on the top of the engine pylons - ...
41
votes
3answers
15k views

Why does supersonic flight detach airflow from a wing?

I've read in several answers to questions that when a wing passes the speed of sound the airflow will become detached from the craft towards the rear quarter of the wing (thus making things like ...
23
votes
2answers
3k 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?...
8
votes
5answers
15k views

What is profile drag?

I know about induced drag, parasite drag, form drag, skin drag, wave drag, and interference drag. But I don't encounter the term profile drag often, and I can't find a good definition of it. Is ...
20
votes
1answer
2k views

What makes snow on the wings during take off so dangerous?

What is the cause of the widely known danger of snow on the wings of the airliner? Why does it require deicing before taking off? I cannot believe it just makes the plane too heavy, and it is not ...
4
votes
2answers
1k views

Do windows on the side of the fuselage increase drag?

I wonder this because I'm not too sure glass is easier for air to travel over than metal.
8
votes
1answer
3k views

Does the Piper PA-28 Cherokee wing have laminar flow behavior?

I've heard (and read) that the PA-28 series has a laminar flow wing: The Piper had a very thick airfoil that used laminar flow to assure that lift would be lost very slowly up to the stall. ...
7
votes
1answer
6k 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 ...
15
votes
2answers
1k views

What phenomenon causes the increase of drag with rain?

I know that rain generally worsens the aerodynamic propeties of an aircraft. I'm wondering what processes cause the increase in drag. I'm mostly interested in General Aviation, thus relatively low ...
6
votes
2answers
2k views

Why are RC rotor blades different from helicopter blades?

Why do toy (RC) helicopters have curved flat surfaces and larger rotors on true helicopters have a solid aerofoil shape? If the rotor was mechanically strong enough to lift the desired weight, is ...
8
votes
3answers
800 views

Why does a turbulent boundary layer cause more friction drag than a laminar boundary layer?

From what I understand, friction is caused by viscosity and a bigger Reynolds number signifies lower viscosity. Thus, a higher Reynolds number(i.e. turbulent flow) results in lower friction. But, ...
3
votes
2answers
587 views

Why is the critical AoA of most flaps 40° when most airfoils stall at 15°?

A plain flap deflected 40 degrees is largely stalled (...) Flaps stall at 40° according to an answer on Quora, why is this so when typical airfoils stall at 15°?
6
votes
1answer
961 views

Is drag coefficient lowest at zero angle of attack?

The drag coefficient of a symmetric airfoil is lowest when its angle of attack is zero. I'm not sure if this is true in general.
2
votes
2answers
2k views

How can the zero-lift drag coefficient (parasitic drag) be calculated?

Consider a 3-D wing made from an arbitrary airfoil, say a NACA0012 airfoil. The wing has a trapezoidal shape, with a fixed span, root chord, and tip chord. Also, assume that the wing loading is known ...

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