Linked Questions

25
votes
2answers
6k views

How do insects decrease aircraft performance?

Is it true that insects hitting the fuselage could decrease aircraft performance and increase fuel consumption? Insects are small in mass. I think even a large amount of them accumulate on the ...
7
votes
5answers
2k views

If I were to build a J3 cub twice the size of the original using the same CG would it fly?

How big of an engine would I need, if the original is 65hp? What would be the weight of the up-scaled plane? Simply twice the weight? What would be the stall speed? How fast would it go? 75mph? Is ...
13
votes
2answers
4k views

Why is the coefficient of drag for straight wings at supersonic speeds lower than for swept wings?

Why is the coefficient of drag of a straight wing lower than the coefficient of drag of a swept back wing at higher supersonic speeds (above, say, Mach 2)?
6
votes
2answers
5k views

How to pick a good airfoil based on Cl and Cd

Let's assume I have 10 different airfoils graphs of Cl x Aoa, Cd x Aoa and Cl/Cd x Aoa. How do I pick the best one that will give me the most efficiency (the longest flight time)? I understand the ...
11
votes
1answer
9k views

What is the relation between an airplane's altitude and the drag it is experiencing?

The Reynolds-Number $Re$ is defined as $Re = \frac{c \cdot L \cdot \rho}{\mu} = \frac{c \cdot L}{\nu}$, with the velocity $c~\left[ \frac{m}{s} \right]$, the reference length $L~\left[ m \right]$, ...
7
votes
1answer
1k 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
4answers
2k views

What is the total wing surface area of the A320?

I was trying to calculate the total area of an A320, and in this link I found the wing area and tail area. But here I read that the wing area is just the 2D projection of the wing. So if I wanted to ...
4
votes
1answer
6k views

How is the zero-lift drag coefficient calculated?

The drag coefficient is usually given as a funtion of the lift coefficient and the zero-lift drag coefficient ($c_{D0}$): $c_D=c_{D0}+k\cdot c_L^2$ How can I calculate/estimate $c_{D0}$?
2
votes
2answers
2k views

Is airfoil thickness proportional to drag coefficient?

Does increase in the thickness of a camber airfoil mean more drag will be produced? Why do slow flying planes have thick airfoils when it will just slow them down even more?
5
votes
4answers
1k views

Is it possible to determine the approximate climb rate of an aircraft knowing its top speed, engine power and weight?

Is it possible to determine the initial climb rate of a craft with a few key pieces of data such as top speed, engine power and weight? For example the XB-42 was an experimental bomber design from ...
4
votes
2answers
715 views

What is the purpose of thinner airfoils used near wing tips?

I know that a thicker airfoil at root will strengthen the root spar but what is the reason behind using thinner airfoils at the tip? Is it because thinner airfoils have higher stalling angles of ...
3
votes
2answers
623 views

Does anyone know an equation relating wingspan to gliding distance for a glider?

I found this equation online but it is not from a reputable source and has no derivation. Could anyone help me by deriving this equation or even verifying its accuracy? I would love to cite and use ...
2
votes
3answers
499 views

How does the power requirement change when weight and speed change?

Suppose I have an airplane with a certain weight M, which uses a certain amount of power P, to fly at a certain speed V. If I use the same airplane, but quadruple the weight (4xM) and double the ...
2
votes
3answers
255 views

Will this simple equation (pic attached) produce a rough estimate of the top speed of a prop driven aircraft?

Calculating the approximate top speed of a vehicle is straightforward. $v = \sqrt[3]{\frac{2P}{c \cdot D \cdot A}}$ where v = velocity of the vehicle P = power of the engine c = coefficient of ...
3
votes
1answer
801 views

Are there any reference values for Cl and Cd of a NACA 0012 airfoil to verify CFD simulations?

I am having trouble finding the established results of inviscid flow CL and Cd variation over NACA 0012 airfoil, for the transonic region. I need the data to verify the results I am getting through my ...

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