Effect Of Design ParametersOf an

OrnithopterBy LOURD ARUN RAJ

MRCET, HYD-BAD

Fig : hand made ornihopter while flying

1.FLAPPING WING MAV:• Birds taught humans to fly.• Leonardo da Vinci’s Studied the bird flight.• Emerged from the dream of mastering the flight of the natural fligher.• Complexity of the insect flight• Bird Flight- Ornithopter.• Insect flight- Entomopter.• Scientists concluded that ornithopter flight is efficient than static wing flight because wing alone produces lift as well as thrust.• 15 cm mark by DARPA

Wing Kinematics:

• Basic Terminology:• Consists of 3 axes 1. Flapping axis. 2. Pitching axes 3. Lead lag

Forces generated by flapping wings:

Divide into two strokes:• Down stroke • Up stroke

• Induced flow is maximum near the tips.• The Angle of attack is varying along the span.• For flexibility, the angle of attack keeps varying with the stroke.

2.Fluid dynamic modeling:• Using BLADE ELEMENT ANALYSIS.• Modeling reality on paper is very difficult.Assumptions :• Wings are made of flexible membrane attached with spar at leading edge and wing form is half

elliptical.• Only flapping would be induced by the power

plant with equal up/down flapping angles.• The front spar will act as pivot for passive

pitching movement, caused by the aerodynamic/ inertial loads.

• The flow is assumed to remain attached.

• Both flapping and pitching movements are taken as sinusoidal functions with certain amount of lag.

• Upstroke and down strokes have equal time duration

Final Equations:

3.Parametric Study and ResultsA MATLAB code has been written and theResults are in graphical format.

•Span=40cm•Root chord=10cm•Mass= 12 gmsAnd other minor values are assumed.

•The graph starts from down stroke and to up stroke.•Time is converted dimensional numbers.

Inputs required to solve:•Forward Speed •Flapping Frequency •Total Flapping Angle •Incidence Angle of the Fuselage •Maximum Pitch Angle •Lag Between Pitching and Flapping • Span wise strips and time steps.

Results:

Change of Lift, Thrust and drag in one cycle with time.

Effect of Forward speed:•The forward speed is varied from 5m/s to 10m/s

Effect of Flapping Frequency:•The Flapping frequency is varied from 4Hz to 16Hz With increment of 2 Hz

Effect of flapping angle:•Flapping angle is varied from 30deg to 90deg

4.Conclusion:•Lift of an ornithopter is most influenced by theincidence angle and forward speed but leastaffected by flapping frequency.•Thrust of an ornithopter is most affected byflapping frequency and forward speed but leastinfluenced by incidence angle.•·The drag force increases with increase in forwardspeed, incidence angle, and flapping frequency.•·The increase in total flapping angle increases allthe forces but the effect is marked on drag force.