swept wing
Join Date: Apr 2009
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Troll or simpleton?
Suggest you get some textbooks and read them. If you simply post every question that occurs to you without any personal research then patience will run thin.
Suggest you get some textbooks and read them. If you simply post every question that occurs to you without any personal research then patience will run thin.
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Join Date: Oct 2007
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Ash,
There is a textbook that will help you with interview prep "ace the technical interview" most of the questions you have posted on here are explained in that book,
Regards
There is a textbook that will help you with interview prep "ace the technical interview" most of the questions you have posted on here are explained in that book,
Regards
Join Date: Apr 2011
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Ash12,
The swept back wing has lower lift capability because the wing "sees" the airflow that is perpendicular to the leading edge. In this sense, a straight wing is most effective, as all the airflow goes over the aerofoil. As we begin to sweep it back, we get less airflow 90 degrees to the leading edge until eventually, if the wing is made completely swept back, the wing has no parpedicular airflow at all over it. Visualise it.
The reason why we want to sweep back the wing of a jet is because it is a high speed aircraft. And high speed aircraft can easily move at a speed which causes the local airflow over the wings to go supersonic. This is undesirable as shockwaves can form (shockwaves are where the flow velocity drops) reducing the lifting capability of the wing (and also producing an undesirable phenemenon known as a mack-tuck). This shock wave happens as a result of the flow that is parpendicular to the wing going supersonic, and by sweeping back, we ensure that this parpendicular component is reduce for any given airspeed. Thus, the aircraft can fly at higher airspeeds before reaching the critical mach number (Mcrit). As I just stated, this parpadicular component is the useful component for lift production, which is reduced by sweeping it back. Therefore, at any given airspeed, the wing is producing less lift than it would if it were not swept back.
This is undesirable during an approach - because we want to come in slow while supporting the aircraft's weight. The swept back wing is already producing less lift than it would had it were not swept back and this is the time when sweep back is not useful to have.
We have to compensate for reduced lift production at low speed of a swept back wing by incorporating techniques such as large slotted fowler flaps which increases the surface area of the wing and accelerates flow over the flaps through the slots and slats on the leading edge to to also accelerate the boundary layer flow over the whole surface of the wing. This reduces the stall speed and increases the lift at any given airspeed thereby compensating the effects of the sweep back.
The swept back wing has lower lift capability because the wing "sees" the airflow that is perpendicular to the leading edge. In this sense, a straight wing is most effective, as all the airflow goes over the aerofoil. As we begin to sweep it back, we get less airflow 90 degrees to the leading edge until eventually, if the wing is made completely swept back, the wing has no parpedicular airflow at all over it. Visualise it.
The reason why we want to sweep back the wing of a jet is because it is a high speed aircraft. And high speed aircraft can easily move at a speed which causes the local airflow over the wings to go supersonic. This is undesirable as shockwaves can form (shockwaves are where the flow velocity drops) reducing the lifting capability of the wing (and also producing an undesirable phenemenon known as a mack-tuck). This shock wave happens as a result of the flow that is parpendicular to the wing going supersonic, and by sweeping back, we ensure that this parpendicular component is reduce for any given airspeed. Thus, the aircraft can fly at higher airspeeds before reaching the critical mach number (Mcrit). As I just stated, this parpadicular component is the useful component for lift production, which is reduced by sweeping it back. Therefore, at any given airspeed, the wing is producing less lift than it would if it were not swept back.
This is undesirable during an approach - because we want to come in slow while supporting the aircraft's weight. The swept back wing is already producing less lift than it would had it were not swept back and this is the time when sweep back is not useful to have.
We have to compensate for reduced lift production at low speed of a swept back wing by incorporating techniques such as large slotted fowler flaps which increases the surface area of the wing and accelerates flow over the flaps through the slots and slats on the leading edge to to also accelerate the boundary layer flow over the whole surface of the wing. This reduces the stall speed and increases the lift at any given airspeed thereby compensating the effects of the sweep back.
