Helicopters- The History

Table of Contents

Introduction3

Basic Aerodynamics4

Differences between Aircrafts & Helicopter7

Hovering8

Forward Flight9

Auto-rotation10

Early Beginning and Development12

The Perfect Power Source14

The Autogiro16

World War II18

The Postwar Period20

Advancements from the Turbine22

The Vietnam War23

The Gulf War26

Sales and Rental27

Air rescue28

Conclusion29

References31

Helicopters- The History

Introduction

The concept of ??an aviation unit capable of vertical lifting is as old as the initial dreams of flight itself. It has always fascinated human mind. Early documents and manuscripts show that in the 4th Century AD a rotary winged toy was produced in China. It is believed that the toy was constructed using a maple seed and a stick with two springs at one end. The toy flew into the air after it was quickly spun in the hands of children.

The very first plans of a machine capable of vertical lift came from the genius Leonardo da Vinci. This implemented the principle of the "Archimedes Screw". Da Vinci designed a "perpetual screw", a concept that led to the modern day propellers on top of helicopters. However, the theory was never realized and Da Vinci did not live to see his genius turn in to reality. It should be noted that a lot of the concepts implemented in the design of modern day helicopters are derived directly from Da Vinci's initial plans.

Helicopters are one of the most prominent challenges that the aviation industry has faced to date. Many early scientists and great thinkers lost their lives to rudimentary testing techniques, poor designs and inadequate understanding of aerodynamics. The challenge can be said to have been conquered after over 500 years of hard work, designing, testing and even loss of life.

This paper discusses the history and the progression of the helicopter to what it is know today. It starts early on around the time of the Wright brothers, travels through both world wars and ends with what the aviation industry hopes for the future (Scorer, 1958).

Basic Aerodynamics

Before one delves into the history of the aircraft, it is best to get a basic grasp on aerodynamics of both fixed wing and rotary wing machines. An airplane is heavier than air, and can only leave the ground if a force acting upwards, which is at least as large as the weight of the aircraft, is applied. This force is called buoyancy, or lift coefficient, and is generated by the wings. The wings have a particular form cross section, the profile. There are many different types of profiles, depending on what the plane's flying characteristics are. What happens is that as the body, or wing, moves forward, the profile divides the air flow into a lower and an upper portion (Katz, 1991). 

Since the air is displaced by the curvature of the profile, it must travel a "way forward", which increases the flow velocity. According to the law of fluid mechanics, the increase in speed leads to a reduction of pressure. Since the upper and lower side of the profile have a different curvature, different "suction" is generated. The resultant force acts upward (lift).

In a fully-symmetrical profile with negative pressure on the upper wing surface is exactly the same size as ...