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Aero II Lecture 33 Propellers II

Stall Speed ExampleSimple Propeller ExamplePropeller designHomework

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Aero II Lecture 33 Propellers II

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    2. Stall Speed Example Simple Propeller Example Propeller design Homework #5 Agenda

    3. Stall Speed

    4. Stall Speed

    5. Stall Speed

    6. Stall Speed Example A wing design has a maximum CL =2.3 at ?=20o with full flaps extended and a wing area of 8 meters squared. The aircraft has a full loaded weight of 1000Kg What is its stall speed at Orlando airport? ( sea level ?air=1.2 kg/m3)

    7. Stall Speed

    10. Propellers

    11. Propeller sections

    12. Propeller Theory

    15. Propeller Calculation We can model a propeller as having an average pitch angle of ?=30o and profile of NACA 2415 and total area of 0.4m2 If we have the propeller turning at n=40rps and it has a diameter of 2meters its average rotational velocity is Vrot=D/4 x 2? x n=126m/sec At 150mph ( 66m/sec) we have angle ?=tan-1(66/126)=27o The average angle of attack on the propeller blade is thus a = b - f = 30o-27o = 3o The total average velocity seen by the propeller is V=(Vrot2 +V2)1/2 = (15876+4356)1/2=142m/sec

    19. Propeller at Takeoff For takeoff the propeller is not so efficient Assume same rotational velocity with no change in pitch

    24. Propeller Theory

    26. Propeller Theory

    27. Wing Spoiler

    28. Ducted fan

    29. Ducted fan

    30. Ducted fan

    31. Ducted fans

    32. propfans

    33. Homework #5 1(30 pts) For the aircraft described earlier what is the stall speed for an overloaded plane of 1600kg mass A. at Orlando B. on the Siachin Glacier ( 4km altitude) 2. (30 pts) For the propeller described earlier A. what is the thrust for n=60rps and V=268mph B. what is the efficiency ? C. sketch the curve of propeller efficiency using the previous two points.

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