Design and Manufacture of an Efficient Ornithopter Wing

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Design and Manufacture of an Efficient
Ornithopter Wing Second Stage Presentation by Mobl
e Benedict Roll No 99D01011 under the guidance
of Prof. Sudhakar K and Prof. K. Kurien
Issac Department of Aerospace
Engineering Indian Institute of
Technology Bombay  
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Introduction

• Efficient wing- a primary requirement
• Kinematics
• Flapping
• Twisting

Ornithopter made in University of Toronto (1991)
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Obtaining the Required Kinematics

• Flapping motion
• By a single actuator at the wing root
• Twisting motion
• By using distributed actuators on the wing
• By having one actuator to rotate the tip of the
  wing relative to root along with suitable elastic
  tailoring
• By using one external flapping actuator and
  relying on the loads along with suitable
  aeroelastic tailoring

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Analytical Part
Experimental Part
Aerodynamic Performance
Compare
Aerodynamic Performance
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Aeroelastic Modelling of the Wing
dynamic part
dynamic part
static part
static part
dynamic part
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The Static part
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The Dynamic part
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Results
Variation of with y
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Results
Variation of Fh with y
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Results
Variation of with y
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Results
Variation of F? with y
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Animation
A frame from the animation showing the wing
deformation
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Aerodynamic Performance Calculation

• Normal force calculation
• Circulatory Normal force
• Normal force due to apparent mass effect
• Chordwise force calculation
• Chordwise force due to camber
• Force due to leading edge suction
• Chordwise friction drag
• Components of the above forces are taken to
  calculate Average Lift and Thrust

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Results
Variation of Average Lift with Flapping Frequency
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Results
Variation of Average Thrust with Flapping
Frequency
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Design of the Flapping Mechanism

• Designed to ensure the required kinematics
• Flapping motion should be as close to harmonic
• Not designed for lightness
• Designed for ground testing
• Detailed analysis of the stresses on the linkages
  were not carried out
• Over-designed for strength

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a is a parameter
EF 1
Transmission angle should be close to 90 degrees
Linkage Synthesis
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Max Deviation9.5
59degltBCDlt121deg
The graph showing the variation of ? with respect
to ?
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Schematic of the Flapping Mechanism
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Gear Wheels

• Two contra-rotating similar gear wheels
• Made of Cast Iron
• Locally strengthened by bracing MS plate
• Drive on one of the gear wheels

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Connecting Rod

• long 12 mm MS pipe
• a U-slot welded at one end
• a pin passed through the U-slot
• MS bush cover welded on the other end
• a brass bush fitted into the bush cover
• bush rotates on a single end threaded pin

L3
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Bearing Assembly

• Two ball bearings
• Bearings fitted using interference fits
• Each part machined to the required dimension

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Rocker

• 12 mm MS pipe
• two plates (with holes) welded at locations A and
  B
• a circular slotted flange welded one end

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Frame

• Two posts of MS pipe welded on to the base plate
• U-slot with pin on the free end of the post

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Future Work

• The construction of the wing
• Devising experiments that will improve
  understanding of the theory

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Wing construction

• Tailoring the flexibility of the wing
• Realizing the shape of the wing with the chosen
  construction materials
• Minimizing the weight of the wing
• Strength and fatigue properties of the
  construction material
• Ease and repeatability of the construction process

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Single Surface Aerofoil
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Proposed Construction Methods

• Complete frame of the wing made using hard
  polyurethane foam and the monokote skin stuck on
  this frame
• The whole frame including the spar and the ribs
  can be made as one piece in a mould
• The spar and ribs can be made separately and then
  stuck together
• The spar and ribs can be machined from a
  polyurethane foam block in one piece

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Testing the Wing

• Placing the whole setup over an appropriate
  platform digital balance
• Strain gauging the root of the wing to capture
  the stresses
• High-speed Photography
• Where to test the wing?

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Validating the Full Model
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Validation of the Aeroelastic Model
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Validation of the Aerodynamic Performance
Calculation
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Validation of the Structural Model
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Demonstration Model
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Thank You