Aircraft Performance

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Prof. Newman, 2004 Page 1 Aircraft Performance Prof. Dava Newman Sr.

Lecturer Pete Young 16.00: Introduction to Aerospace & Design 12 February 2004 Prof. Newman, 2004 Page 2 Lecture Outline " Performance Parameters 3Aircraft components and examples " Equations of Motion " Thrust-Velocity Curves 3Stall 3Lift-to-Drag Ratio " Endurance & Range " V-n Diagrams Prof. Newman, 2004 Page 3 Performance " Note: Book errata pdf file " Speed: minimum and maximum?

" Range: How far? " Endurance: How long? 3Flight dynamics Prof.

Newman, 2004 Page 4 Aircraft Components Prof. Newman, 2004 Page 5 Aircraft Performance/Design Elements " First example: 3Semi-scale Mustang cReno Racer d 3~ 750 cm span, 450 grams weight Prof. Newman, 2004 Page 6 Aircraft Performance/Design Elements " Second example: cOmega d high performance motor-glider " ~ 1.8 m span, 300 grams weight Prof.

Newman, 2004 Page 7 Discussion Topic " What are the differing aerodynamic design features providing the desired performance for each aircraft? " Common features: 3Aero controls: elevator, ailerons, rudder 3Electric motor: identical 3 Radio receiver and servo motors: identical Prof. Newman, 2004 Page 8 Desired performance " Reno Racer: high speed aerobatics and racing 320-25 m/s velocity in level flight 3 cHigh g d turns and rolls " ... more. less.

Omega: steep rapid climbs to altitude; efficient power-off glides for extended duration Prof. Newman, 2004 Page 9 Design Elements " Aspect Ratio (b 2 /S) 3Low or high? Why? " Drag reduction: how attained? " Airfoils: low or high camber? Why? " Tail moment arm (horizontal stab area x tail length): high or low? Why? " Wing loading (wing area/weight) high or low? What effect on flight? " Any other differing design features? Prof. Newman, 2004 Page 10 Equations of Motion " 2-D model of aircraft " Lift, Drag, Weight and Thrust " Velocity, v " Flight path, q or g 3Velocity & horizontal " Pitch angle 3Nose & horizontal Prof. Newman, 2004 Page 11 Thrust-Velocity Curves " The relationship between the required thrust and the velocity can be calculated for any aircraft. Prof. Newman, 2004 Page 12 Thrust-Velocity Simulation " Simulations https://web. mit .edu/16.00/www/3/03/index.html " Foil Sim http://www.lerc.nasa.gov/WWW/K-12/airplane/foil2.html " Air Density Simulator http://www.flyers.org/simulators/atmospheric.htm "Stall "Maximum Lift/Drag Prof. Newman, 2004 Page 13 Range & Endurance (Breguet) " Aerodynamics & Engines (propeller, jets) 3m o = a/c, kg 3m f = mass of fuel, kgm= m o +m f 3Ùm f = fuel mass flow rate, kg/s " Range: total distance on a tank of fuel 3(L/D) max (C L 1/2 / C D ) max or v(L/D) " Endurance: total time a/c can stay aloft on a tank of fuel 3(C L 3/2 / C D ) max (L/D) max Prof. Newman, 2004 Page 14 Range & Endurance Prof. Newman, 2004 Page 15 V-n Diagrams (Flight Envelope) " Operational Velocity-Load (in g 9s, denoted by 8n 9) envelope " Aerodynamic " Structural " Simulator 3Stall limit: aerodynamic 3Corner Velocity or Maneuver point 3Structural limit Prof. Newman, 2004 Page 16 Examples " Example 4.6, pg. 90, V-n Simulation " Problem 4.6 Calculate the thrust required for an aircraft, modeled after a Canadair Challenger Business Jet, to maintain steady level flight of 350 knots at an altitude of 6500 meters. Assume the following characteristics for the aircraft: Weight = 16,350 kg, Wing area = 48.31, Wing span = 19.61 m, Parasite drag = C Do = 0.02, Oswald efficiency factor = e = 0.8 Prof. Newman, 2004 Page 17 Questions? " Mud Cards

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