# Aerodynamics

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1. Which of the following statements is correct?

1.

Separation on a wing is driven by an increase in pressure in flow direction (diverse pressure gradient). This makes the flow unstable and causes a transition to turbulence, which makes the flow separate.

2.

Separation on a wing is driven by an increase in pressure in flow direction (adverse pressure gradient). This slows down the flow close to the wall and eventually will cause separation. The separation point on the aerofoil is characterised by vanishing wall shear stress.

3.

Separation on a wing is driven by an decrease in pressure in flow direction (adverse pressure gradient). This lifts the flow from the wall and makes it separate. After separation the flow is turbulent.

4.

Separation on the wing is driven by the friction in the boundary layer which causes a decrease in pressure. This makes the flow turn away from the surface generating a low pressure bubble on the surface.
2. A General Aviation plane of 3,484 kg flies at its best lift/drag ratio with constant speed at an altitude of 2,041 m. The engine provides a thrust of 1,283 N to overcome drag.

Suddenly the engine fails. What is the maximum distance the plane can cover to find a suitable emergency landing spot (in km)?
3. A large airliner has a mass of 301,095 kg, a wing area of 720 m2. The wing in high lift configuration has a maximum lift coefficient of cl,max = 2.

If the landing speed has to be 20% above the stall speed, what is the landing speed for this aircraft (in m/s)?

Use g=9.81 m/s2
4. Assume, that the velocity is constant on the upper and lower part of a wing with area 37 m2, and that the velocity on the lower surface of the wing is the same as the flight speed of 111 m/s.

What does the velocity on the upper surface need to be to produce enough lift for take-off of a 2,966 kg plane?
5. Im not sure if this is to do with aerodynamics but from my first year flight mech module we solve similar problems and we use the Brequet range equation (s)
6. So you calculate your L/D by doing mg/D, then you just multiply your L/D (which is equal to the glide ratio) by the altitude. You should get around 55km.

Breguet range equation requires fuel usage and an engine so it doesn't really work in this case.
7. (Original post by Romello95)
Which of the following statements is correct?
1.Separation on a wing is driven by an increase in pressure in flow direction (diverse pressure gradient). This makes the flow unstable and causes a transition to turbulence, which makes the flow separate.
2.Separation on a wing is driven by an increase in pressure in flow direction (adverse pressure gradient). This slows down the flow close to the wall and eventually will cause separation. The separation point on the aerofoil is characterised by vanishing wall shear stress.
3.Separation on a wing is driven by an decrease in pressure in flow direction (adverse pressure gradient). This lifts the flow from the wall and makes it separate. After separation the flow is turbulent.
4.Separation on the wing is driven by the friction in the boundary layer which causes a decrease in pressure. This makes the flow turn away from the surface generating a low pressure bubble on the surface.
Which do you think, and why?

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