🕊️ Ornithopter – Flapping Wing Mechanism

Machine Design (ME205) Laboratory Project

IIT Ropar | Second Semester (2023–2024)
Group C/11 (Friday)

Submitted by:

• Sumit Yadav (2022MEB1352)
• Sunny Bharti (2022MEB1353)
• Tanish Goyal (2022MEB1356)
• Tarini Magotra (2022MEB1358)
• Tejasva Jindal (2022MEB1359)

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📘 Project Overview

An ornithopter is an aircraft that achieves flight by flapping its wings, mimicking the flight mechanism of birds and insects.
Unlike fixed-wing aircraft that rely on continuous forward motion, an ornithopter generates both lift and propulsion through the oscillatory motion of its wings.

This project aimed to design and construct a functional ornithopter mechanism using multiple four-bar linkages, and to perform velocity analysis of its moving components.

The entire model was designed and analyzed using SolidWorks, with a focus on mechanical design optimization and basic aerodynamic analysis.

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🎯 Objectives

• Design and model an ornithopter mechanism using SolidWorks.
• Perform velocity analysis of multiple links.
• Study and analyze airfoil performance to optimize lift and thrust.
• Develop a gear train for motion transmission.
• Implement a motor-driven flapping mechanism.
• Create a lightweight and robust prototype with 3D-printed components.

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🧠 Work Breakdown (Weekly Progress)

Week 1:

• Studied ornithopter mechanisms.
• Designed individual links in SolidWorks for the flapping mechanism.

Week 2:

• Analyzed different airfoils (NACA series) to understand lift characteristics.
• Designed gears based on module, addendum, and dedendum values.

Week 3:

• Rescaled the prototype.
• Performed velocity analysis of linkage motion.

Week 4:

• Assembled the full system and tested mechanical motion.

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⚙️ Mechanical Design

Gear Design

• Type: Spur gears (low friction and high efficiency).
• Number of Teeth: 25
• Module: 2 mm
• Pressure Angle: 20°
• Pitch Circle Radius: 50 mm
• Gear Reduction Ratio: 8/25 (Driver/Driven)

The reduction slows down the motor’s high RPM to match realistic wing-beat frequencies for efficient flapping.

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Linkage Design

• Multiple four-bar linkages were used to convert rotary motion into oscillatory flapping.
• Iterative testing was performed to optimize link lengths and pivot distances for smooth, synchronized motion.

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🪶 Airfoil Analysis

Airfoil Chosen: NACA 4404

• Chosen for high lift-to-drag ratio and delay in stall onset.
• Designed and simulated in SolidWorks Flow Simulation.
• Low Reynolds number regime considered (based on low-speed flight assumption).
• Roughness length factor: 0.1 m (agricultural terrain equivalent).

Key Finding:
At low-speed flight conditions, NACA 4404 provides stable lift with minimal flow separation — ideal for small-scale flapping mechanisms.

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⚡ Electronics and Control

Motor Selection

• Type: DC Motor
• Speed: 48 RPM
• Torque: ~5 N·m
• Chosen to match mechanical load and flapping frequency.

Arduino Code (Snippet)

const int button1 = 9;
const int button2 = 8;
const int button3 = 7;
int en = 10;
int i1 = 11;
int i2 = 12;
int a = 100;

void setup() {
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(button3, INPUT_PULLUP);
  pinMode(en, OUTPUT);
  pinMode(i1, OUTPUT);
  pinMode(i2, OUTPUT);
  Serial.begin(9600);
  analogWrite(en, a);
  digitalWrite(i1, HIGH);
  digitalWrite(i2, LOW);
}

void loop() {
  int b1 = digitalRead(button1);
  int b2 = digitalRead(button2);
  int b3 = digitalRead(button3);
  if (b1 == LOW) { a = min(255, a + 50); }
  else if (b2 == LOW) { a = max(0, a - 50); }
  else if (b3 == LOW) { digitalWrite(i1, !digitalRead(i1)); digitalWrite(i2, !digitalRead(i2)); }
  analogWrite(en, a);
  delay(500);
}