1 / 9

AE 1350 Lecture Notes #10

AE 1350 Lecture Notes #10. TOPICS TO BE STUDIED. Take-off and Landing Performance There is considerable variations due to pilot technique ground conditions FAR 25 regulations cover how take-off and landing distances must be computed.

simone
Download Presentation

AE 1350 Lecture Notes #10

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. AE 1350 Lecture Notes #10

  2. TOPICS TO BE STUDIED • Take-off and Landing Performance • There is considerable variations due to • pilot technique • ground conditions • FAR 25 regulations cover how take-off and landing distances must be computed. • In your design, estimate wing area S to meet specified take-off and landing distances.

  3. Takeoff Performance Theory We attempt to compute the ground roll as accurately as possible. Add an extra 20% distance to account for transition and climb. Rotate to take-off Transition and climb 20% of total takeoff distance, from experience Ground Roll 80% of total takeoff distance, from experience.

  4. Ground Roll Let v be the aircraft speed. dv/dt = a where a= acceleration of the vehicle a= (All horizontal forces acting on the aircraft) / (Mass of aircraft) Assume “a” to be a constant. Integrate: v = at Velocity at lift-off vLO = a tLO Integrate again: d = 1/2 a t2 dLO = 1/2 a t2LO = v2LO/(2a)

  5. Ground Roll (Continued) From the previous slide, the total roll distance is dLO = 1/2 a t2LO = v2LO/(2a) a = Acceleration of the aircraft due to horizontal forces on it. These forces are: Thrust, Drag, Ground Friction Thrust far exceeds the other two factors during takeoff. Thus, a = T/(Aircraft Mass) = T g/ (W) Then, total roll distance is dLO = v2LO/(2a) = v2LO. W/(2Tg)

  6. Ground Roll (Continued) Total roll distance dLO = v2LO. W/(2Tg) The pilot usually lifts off at 1.2 times stall velocity. Stall velocity VStall is defined from: 1/2 r V2Stall CLmax S= W V2Stall= W/(1/2 r CLmax S) v2LO =(1.2 VStall)2 = 1.44 W/(1/2 r CLmax S) Then, dLO = v2LO. W/(2Tg)= 1.44 (W)2 / (TgrS CLmax) Include factors of safety for transition and climb: Take-off Distance, in feet = 37.5 (W)2 / (TsS CLmax) = 37.5 (W/S) /[(T/W)s Clmax] where s = Density Ratio = r/rSea-Level,,W in lbs, S in square feet

  7. Landing Performance There is considerable scatter in landing distances due to use of spoiler, brakes, reverse thrust, human factors ground conditions : wet runway , dry runway

  8. FAR-25 RegulationsLanding Performance Vapproach=VA=1.3 Vstall for civilian aircraft Vapproach=VA=1.2 Vstall for military aircraft Vapproach=VA=1.1 Vstall for carrier based aircraft 50ft Ground Roll Total Landing Distance, in feet = 0.3 (Vapproach in knots)2 These results are empirical, because of variations in pilot technique.

  9. Lift Coefficients for your Design • For fighter design, use the following Clmax • With flaps up, 1.2 - 1.8 • With flaps down, during take-off: 1.4 - 2.0 • With flaps down, during landing: 1.6 to 2.6 • For transport design, use the following Clmax • With flaps up, 1.2 - 1.8 • With flaps down, during take-off: 1.6 - 2.2 • With flaps down, during landing: 1.8 to 2.8

More Related