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All about Rotary Wing Aircraft



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Modern Rotary Wing aircraft are the fulfillment of the second oldest vision of flight. The first was to fly like a bird with straight, flapping wings.

The second vision was to "corkscrew" into the air kind of like a propeller in water. In fact some early designs were derived from water movers. But it soon became obvious that air and water are very different things.

Many believe Leonardo DaVinci invented the concept in the early 15th century. However, this ignores an earlier independent working Chinese toy created 1,100 years earlier.

The concept of the rotary wing is actually simple in theory. You create lift by moving the wing through the air. Lift was balanced by having equal wings on opposite sides of the drive shaft.

Two problems became apparent when the theory became practice:

- Torque created by the energy of the blades as soon as the vehicle lifted off, and,
- Balancing lift and thrust to create stable flight.

A semi functional craft called an autogiro appeared around 1904 in France. It had an unpowered main rotor that created lift by converting gravity into motion.

Confusing yes, but permit me to explain: The autogiro body doesn't create enough lift to stay in the air. As it moves forward and tries to fall at the same time, wind flows over the rotor blades. The air moving over the airfoil shape of the rotor blades create lift.

The blades begin to move around their shaft and their momentum creates and maintains lift for the duration of the flight.

A Russian immigrant to the United States, Igor Sikorsky created the first safe and practical rotary wing aircraft. He worked on the idea of using a tail rotor to cancel out the tendency to for the body to counter-rotate.

His prototype, the VS-300 first flew in 1940.

The incredible flexibility of the rotary wing has permitted flying feats impossible with any other class of airship.

A balloon can hover over a stationary spot as long as it is tethered to that spot. A helicopter can hover freely for as long as the pilot chooses then move on to another location.

This feature has permitted emergency rescue in places previously beyond the reach of aid. A helicopter can reach a capsized ship faster than a rescue boat. And it can pick up the survivors unlike an aircraft.

This feature was first discovered by the military. Helicopters were being used as observation platforms at first. Them it was noticed that they could be used to quickly get the wounded to medical treatment directly from the battlefield.

Civilians eventually put this concept in to practice as helicopters moved into non-military roles. Many cities in developed countries have dedicated Life Flight programs to get ill or injured citizens to medical treatment.

The advantage is they are not affected by traffic conditions, blockages or limited by available runways. The large hospitals all have a helipad on their rooftops.

Helicopters also serve in law enforcement support, using sensors developed for the battlefield to track felons fleeing on foot or by vehicle. They can also search large areas for victims, lost children or hidden pot fields.

Rotary wing aircraft are doing another kind of duty in firefighting, especially in remote areas like the canyons of Southern California. A helicopter can deliver water and fire retardant accurately and can sometimes be used to rescue firefighters cutoff by shifting flames.

It should be noted that heat, turbulence and low air density caused by fire can disrupt the lift on a rotary wing.

The latest incarnation of the rotary wing is the "Hammerhead." The US Marine Corps has recently placed the V-22 Osprey into action in Afghanistan and Iraq.

A tricky and complicated device, the Osprey had a difficult birth; plagued by crashes deaths and cost overruns. However, the final result is impressive and might well prove to be worth the investment.

The Osprey is the world's first tilt rotor air craft. It uses two large rotors mounted at the end of the wing booms in a configuration reminiscent of Igor Sikorsky's first models. It can take off and land like any helicopter in very tight places without the need of a runway.

The difference is once the Osprey is airborne it can tilt the rotors forward and fly like an airplane. It will carry 24 combat troops or 10 tons of cargo at speeds twice that of the fastest helicopter.

The tilt rotor concept will make its way into civilian applications, like every other advance in rotary wing technology. Once fully mature and made safe by the Marines; private industry will begin to exploit its advantages.

Regional commuter flights will be dominated by tilt rotor craft. You would be able to go to a small downtown pad in San Francisco to catch a business flight. An hour or two later you could be in Los Angeles, Las Vegas or Seattle.

Most importantly, you could disembark right in town or at your destination without the hassle of airports, lost luggage or city traffic. This is the fulfillment of the original helicopter dream . . . at least for the past century.

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