# At each subsequent dynamic pressure 120psf and 150psf

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Chapter 21 / Exercise 22
Heavy Duty Truck Systems
Bennett
Expert Verified
At each subsequent dynamic pressure, 120psf and 150psf, a distinct frequency or tone was heard. The Wright Flyer model was singing to us!
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Chapter 21 / Exercise 22
Heavy Duty Truck Systems
Bennett
Expert Verified
Lift How -is it generated? (Pilot’s Handbook of aeronautical knowledge - FAASo says the FAA! But How Mr. FAA does this happen ?Applying Bernoulli’s Equation/ Principle and the Continuity Equation , the increase in the speed of the air across the top of an airfoil produces a drop in pressure.This lowered pressure is a component of total lift. The pressure difference between the upper and lower surface of a wing alone “
Question time?
Parasite DragDescribes the resistance of the air produced by any part of the airplane that does not produce lift.Types:Pressure drag- > frontal area of the airplane components, exposed to airstream.> Called form(shape) drag* Streaming is necessary to reduce this type of drag and thus increase aircraft efficiency and speed.Factor of Parasite DragStreamlining, density of air ,larger size of object, Speed increases.*
Parasite Drag versus skin friction
Parasite Drag-Pressure dragSkin friction-that part of pressure drag that is not totally eliminated by streamliningIncreases if surface is dirty or rough
Parasite drag- Interference dragInterference Drag> caused by adjacent parts of the airplane, such as the intersection of wings and tail sections with fuselage.* fairings- used to streamline these intersections and decrease interference drag
Interference DragAt CALTech-Pasadena, CalifFirst Project- 1930s,the DC-1, the forerunner of the famous DC-3 aircraft.The DC-1 was plagued by unusual buffeting in the region where the wing joined the fuselage.The sharp corners at the juncture caused severe flow separation, which resulted in high drag, and the vortices separated and buffet the tail.Solution was new pioneering to fair the trailing edge of the wing smoothly into the fuselage.Found by trail and error in wind tunnel. The added filet solved the problems.Fillets have become a standard in aircraft design. Example of how university research in 1930s contributed directly to practical aircraft design.
Drag-wingThe resultant force on an airfoil flying at a specified speed and angle of attack fig 3-23It is possible to break down the resultant into two major components- Lift and drag.The component perpendicular to the relative wind is lift. The component parallel to the relative wind is drag.> the drag is from skin friction and pressure dragover the wing due to flow separation.
Drag from Skin friction and flow separation of airflow on the wing
Drag on the wing-two typesDrag on the wing comes from two different sources:see fig 5-461. The component R 1 parallel to V infinity is the drag D 1 due to skin friction and pressure drag due flow separation.