# An Introduction to Helicopter Aerodynamics

A first-principles approach to understanding the physics, design and performance of helicopters

This is meant to be an exposition of the simple, yet elegant models used to understand the working and performance of a helicopter. Using first principles, thought experiments and the occasional Hollywood video, learners will understand how to gauge the efficiency of a rotor, and how to predict its performance (even on distant planets!). They will grasp how a rotor operates in climb and how to produce the universal inflow curve. They will gather the necessary tools and techniques to predict the descent rate of a maple seed when it is in an ‘autorotative’ state. The asymmetries inherent to forward flight will also be covered in detail. Using a hybrid model, they will be learn how to compute the inflow variation across the rotor disk. Students will finally be exposed to the fundamentals of efficient rotor design (‘optimum’ vs ‘ideal’ rotors) before an in-depth look into the calculation of typical helicopter performance metrics (maximum speed, service ceiling etc).

What you’ll learn

• Grasp the physics behind the working of a helicopter rotor under a variety of flight conditions.
• Using models of increasing complexity, derive expressions linking thrust and power of a rotor to flow and geometry variables.
• Design ‘ideal’ and ‘optimum’ rotors using the Blade-Element-Momentum-Theory model.
• Learn how to estimate important helicopter performance metrics such as climb rates, maximum speed, service ceiling etc.

Course Content

• Introduction –> 2 lectures • 42min.
• Momentum Theory –> 9 lectures • 5hr 54min.
• Blade Element Theory –> 3 lectures • 1hr 25min.
• Blade Element Momentum Theory –> 4 lectures • 1hr 32min.
• Performance –> 2 lectures • 1hr 9min.

Requirements

This is meant to be an exposition of the simple, yet elegant models used to understand the working and performance of a helicopter. Using first principles, thought experiments and the occasional Hollywood video, learners will understand how to gauge the efficiency of a rotor, and how to predict its performance (even on distant planets!). They will grasp how a rotor operates in climb and how to produce the universal inflow curve. They will gather the necessary tools and techniques to predict the descent rate of a maple seed when it is in an ‘autorotative’ state. The asymmetries inherent to forward flight will also be covered in detail. Using a hybrid model, they will be learn how to compute the inflow variation across the rotor disk. Students will finally be exposed to the fundamentals of efficient rotor design (‘optimum’ vs ‘ideal’ rotors) before an in-depth look into the calculation of typical helicopter performance metrics (maximum speed, service ceiling etc).

The course will cover and use the following three models in a variety of conditions:

(1) Momentum Theory

(3) Blade Element Momentum Theory (BEMT)

When applicable, lectures will be accompanied with optional Python scripts for interested students to run and extend.

Get Tutorial