Helicopter

In this episode of the I Can't Sleep Podcast, fall asleep learning about helicopters. Get ready to yawn as I talk about the intricacies of rotor aerodynamics and blade angles. Trust me, it's way more thrilling than it sounds. But wait, it gets even better! I'll also be diving into the exciting topic of helicopter engines. Get ready to doze off as I discuss the different types of engines, their components, and how they work. It's like watching paint dry, but with more noise. Happy sleeping!

Transcript

Welcome to the I Can't Sleep podcast,

Where I read random articles from across the web to bore you to sleep with my soothing voice.

I'm your host,

Benjamin Boster.

Today's episode is from a Wikipedia article titled,

Helicopter.

A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors.

This allows the helicopter to take off and land vertically,

To hover,

And to fly forward,

Backward,

And laterally.

These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of short take-off and landing,

STOL,

Or short take-off and vertical landing,

STOVL,

Aircraft cannot perform without a runway.

In 1942,

The Sikorsky R-4 became the first helicopter to reach full-scale production.

Although most earlier designs used more than one main rotor,

The configuration of a single main rotor accompanied by a vertical anti-torque tail rotor,

I.

E.

Unicopter,

Not to be confused with the single-blade monocopter,

Has become the most common helicopter configuration.

However,

Twin main rotor helicopters,

Bicopters,

In either tandem or transverse rotors configurations,

Are sometimes in use due to their greater payload capacity than the monorotor design.

And coaxial rotor,

Tilt rotor,

And compound helicopters are also all flying today.

Quad rotor helicopters,

Quadcopters,

Were pioneered as early as 1907 in France,

And along with other types of multicopters have been developed mainly for specialized applications such as drones.

Etymology The English word helicopter is adapted from the French word hélicoptère,

Coined by Gustave Ponton de Macour in 1861,

Which originates from the Greek helix,

Spiral,

Whirl,

Convolution,

And teron,

Wing.

For various reasons,

The word is often erroneously,

From an etymological point of view,

Analyzed by English speakers into heli and copter,

Leading to words like helipad and quadcopter.

English language nicknames for a helicopter include chopper,

Copter,

Heli,

And whirlybird.

In the United States military,

The common slang is helo,

Pronounced with the long e.

Design characteristics A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more horizontally spinning rotors.

By contrast,

The autogyro or gyroplane and gyrodyne have a free spinning rotor for all or part of the flight envelope,

Relying on a separate thrust system to propel the craft forwards so that the airflow sets the rotor spinning to provide lift.

The compound helicopter also has a separate thrust system,

But continues to supply power to the rotor throughout normal flight.

Rotor system The rotor system,

Or more simply rotor,

Is the rotating part of a helicopter that generates lift.

A rotor system may be mounted horizontally as main rotors are,

Providing lift vertically,

Or it may be mounted vertically such as a tail rotor to provide horizontal thrust to counteract torque from the main rotors.

The rotor consists of a mast,

Hub,

And rotor blades.

The mast is a cylindrical metal shaft that extends upwards from the transmission.

At the top of the mast is the attachment point for the rotor blades called the hub.

Main rotor systems are classified according to how the rotor blades are attached and move relative to the hub.

There are three basic types,

Hingeless,

Fully articulated,

And teetering,

Although some modern rotor systems use a combination of these.

Anti-torque Most helicopters have a single main rotor,

But torque created by its aerodynamic drag must be countered by an opposed torque.

The design that Igor Sikorsky settled on for his VS-300 was a smaller tail rotor.

The tail rotor pushes or pulls against the tail to counter the torque effect,

And this has become the most common configuration for helicopter design,

Usually at the end of a tail boom.

Some helicopters use anti-torque controls instead of the tail rotor,

Such as the ducted fan called finestron or fantail,

And nodar.

Nodar provides anti-torque similar to the way a wing develops lift through the use of the Coanda effect on the tail boom.

The use of two or more horizontal rotors turning in opposite directions is another configuration used to counteract the effects of torque on the aircraft without relying on an anti-torque tail rotor.

This allows the power normally required to be diverted for the tail rotor to be applied fully to the main rotors,

Increasing the aircraft's power efficiency and lifting capacity.

There are several common configurations that use the counter-rotating effect to benefit the rotorcraft.

Tandem rotors are two counter-rotating rotors with one mounted behind the other.

Transverse rotors are a pair of counter-rotating rotors transversely mounted at the ends of fixed wings or outrigger structures.

Now used as tilt rotors,

Some early model helicopters had used them.

Coaxial rotors are two counter-rotating rotors mounted one above the other with the same axis.

Intermeshing rotors are two counter-rotating rotors mounted close to each other at a significant angle to let the rotors intermesh over the top of the aircraft without colliding.

Aircraft utilizing this is known as a synchroptor.

Multirotors make use of three or more rotors.

Specific terms are also used depending on the exact amount of rotors,

Such as tricopter,

Quadcopter,

Hexacopter,

And octocopter.

For three rotors,

Four rotors,

Six rotors,

And eight rotors respectively,

Of which quadcopter is the most common.

Multirotors are primarily used on drones and use on aircraft with a pilot is rare.

Tip jet designs let the rotor push itself through the air and avoid generating torque.

Engines The number,

Size,

And type of engines used on a helicopter determines the size,

Function,

And capability of that helicopter design.

The earliest helicopter engines were simple mechanical devices,

Such as rubber bands or spindles,

Which relegated the size of helicopters to toys and small models.

For a half-century before the first airplane flight,

Steam engines were used to forward the development of the understanding of helicopter aerodynamics,

But the limited power did not allow for manned flight.

The introduction of the internal combustion engine at the end of the 19th century became the watershed for helicopter development as engines began to be developed and produced that were powerful enough to allow for helicopters able to lift humans.

Early helicopter designs utilized custom-built engines or rotary engines designed for airplanes,

But these were soon replaced by more powerful automobile engines and radial engines.

The single most limiting factor of helicopter development during the first half of the 20th century was that the amount of power produced by an engine was not able to overcome the engine's weight in vertical lift.

This was overcome in early successful helicopters by using the smallest engines available.

When the compact,

Flat engine was developed,

The helicopter industry found a lighter-weight power plant easily adapted to small helicopters,

Although radial engines continued to be used for larger helicopters.

Piston-line engines revolutionized the aviation industry,

And the turboshaft engine for helicopter use,

Pioneered in December 1951 by Kaman K-225,

Finally gave helicopters an engine with a large amount of power and a low weight penalty.

Turboshafts are also more reliable than piston engines,

Especially when producing the sustained high levels of power required by a helicopter.

The turboshaft engine was able to be scaled to the size of the helicopter being designed,

So that all but the lightest of helicopter models are powered by turbine engines today.

Special jet engines developed to drive the rotor from the rotor tips are referred to as tip jets.

Tip jets powered by a remote compressor are referred to as cold tip jets,

While those powered by a combustion exhaust are referred to as hot tip jets.

An example of a cold jet helicopter is the Sudwest Jinn.

An example of the hot tip jet helicopter is the YH-32 Hornet.

Some radio-controlled helicopters and smaller,

Helicopter-type unmanned aerial vehicles use electric motors or motorcycle engines.

Radio-controlled helicopters may also have piston engines that use fuels other than gasoline,

Such as nitromethane.

Some turbine engines commonly used in helicopters can also use biodiesel instead of jet fuel.

There are also human-powered helicopters.

Flight Controls A helicopter has four flight control inputs.

These are the cyclic,

The collective,

The anti-torque pedals,

And the throttle.

The cyclic control is usually located between the pilot's legs and is commonly called the cyclic stick or just cyclic.

On most helicopters,

The cyclic is similar to a joystick.

However,

The Robinson R-22 and Robinson R-44 have a unique teetering bar cyclic control system,

And a few helicopters have a cyclic control that descends into the cockpit from overhead.

The control is called the cyclic because it changes cyclic pitch of the main blades.

The result is to tilt the rotor disc in a particular direction,

Resulting in the helicopter moving in that direction.

If the pilot pushes the cyclic forward,

The rotor disc tilts forward,

And the rotor produces a thrust in the forward direction.

If the pilot pushes the cyclic to the side,

The rotor disc tilts to that side and produces thrust in that direction,

Causing the helicopter to hover sideways.

The collective pitch control,

Or collective,

Is located on the left side of the pilot's seat with a settable friction control to prevent inadvertent movement.

The collective changes the pitch angle of all the main rotor plates collectively,

I.

E.

All at the same time,

And independently of their position.

Therefore,

If a collective input is made,

All the blades change equally,

And the result is a helicopter increasing or decreasing in altitude.

A swashplate controls the collective and cyclic pitch of the main blades.

The swashplate moves up and down along the main shaft to change the pitch of both blades.

This causes the helicopter to push air downward or upward,

Depending on the angle of attack.

The swashplate can also change its angle to move the blades angle forwards or backwards,

Or left and right to make the helicopter move in those directions.

The anti-torque pedals are located in the same position as the rudder pedals in a fixed wing aircraft,

And serve a similar purpose,

Namely to control the direction in which the nose of the aircraft is pointed.

Application of the pedal in a given direction changes the pitch of the tail rotor blades,

Increasing or reducing the thrust produced by the tail rotor,

And causing the nose to yaw in the direction of the applied pedal.

The pedals mechanically change the pitch of the tail rotor,

Altering the amount of thrust produced.

Helicopter rotors are designed to operate in a narrow range of RPM.

The throttle controls the power produced by the engine,

Which is connected to the rotor by a fixed ratio transmission.

The purpose of the throttle is to maintain enough engine power to keep the rotor RPM within allowable limits,

So that the rotor produces enough lift for flight.

In single engine helicopters,

The throttle control is a motorcycle-style twist grip mounted on the collective control,

While dual engine helicopters have a power level for each engine.

Compound Helicopter A compound helicopter has an additional system for thrust,

And typically small stubbed fixed wings.

This offloads the rotor and cruise,

Which allows its rotation to be slowed down,

Thus increasing the maximum speed of the aircraft.

The Lockheed AH-56A Cheyenne diverted up to 90% of its engine power to a pusher-propeller during forward flight.

There are three basic flight conditions for a helicopter.

Hover,

Forward flight,

And the transition between the two.

Hovering is the most challenging part of flying a helicopter.

This is because a helicopter generates its own gusty air while in a hover,

Which acts against the fuselage and flight control surfaces.

The result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be.

Despite the complexity of the task,

The control inputs in a hover are simple.

The cyclic is used to eliminate drift in the horizontal plane,

That is to control forward and back,

Right and left.

The collective is used to maintain altitude.

The pedals are used to control nose direction or heading.

It is the interaction of these controls that makes hovering so difficult,

Since an adjustment in any one control requires an adjustment of the other two,

Creating a cycle of constant correction.

Transition from Hover to Forward Flight As a helicopter moves from hover to forward flight,

It enters a state called translational lift,

Which provides extra lift without increasing power.

This state most typically occurs when the airspeed reaches approximately 16-24 knots,

And may be necessary for a helicopter to obtain flight.

Forward Flight In forward flight,

A helicopter's flight controls behave more like those of a fixed-wing aircraft.

Applying forward pressure on the cyclic will cause the nose to pitch down,

With a resultant increase in airspeed and loss of altitude.

Aft cyclic will cause the nose to pitch up,

Slowing the helicopter and causing it to climb.

Increasing collective power while maintaining a constant airspeed will induce a climb while decreasing collective will cause a descent.

Coordinating these two inputs,

Down collective plus aft cyclic or up collective plus forward cyclic,

Will result in airspeed changes while maintaining a constant altitude.

The pedals serve the same function on both a helicopter and a fixed-wing aircraft to maintain balanced flight.

This is done by applying a pedal input in whichever direction is necessary to center the ball in the turn and bank indicator.

Uses Due to the operational characteristics of the helicopter,

Its ability to take off and land vertically and to hover extended periods of time,

As well as the aircraft's handling properties under low airspeed conditions,

It has proved advantageous to conduct tasks that were previously not possible with other aircraft or were time or work intensive to accomplish on the ground.

Today helicopter uses include transportation of people and cargo,

Military uses,

Construction,

Fire-flighting,

Search and rescue,

Tourism,

Medical transport,

Law enforcement,

Agriculture,

News and media,

And aerial observation,

Among others.

A helicopter used to carry loads connected to long cables or slings is called an aerial crane.

Aerial cranes are used to place heavy equipment,

Like radio transmission towers and large air conditioning units,

On the tops of tall buildings,

Or when an item must be raised up in a remote area,

Such as a radio tower raised on top of a hill or mountain.

Helicopters are used as aerial cranes in the logging industry to lift trees out of terrain where vehicles cannot travel and where environmental concerns prohibit the building of roads.

These operations are referred to as long line because of the long single sling line used to carry the load.

In military service,

Helicopters are often used for delivery of outside slung loads that would not fit inside ordinary cargo aircraft,

Artillery pieces,

Large machinery,

Field radars,

Communications gear,

Electrical generators,

Or pallets of bulk cargo.

In military operations,

These payloads are often delivered to remote locations,

Made inaccessible by mountains or riverine terrain,

Or naval vessels at sea.

In electronic news gathering,

Helicopters have provided aerial views of some major news stories and have been doing so from the late 1960s.

Helicopters have also been used in films,

Both in front and behind the camera.

The largest single non-combat helicopter operation in history was the Disaster Management Operation following the 1986 Chernobyl nuclear disaster.

Hundreds of pilots were involved in airdrop and observation missions,

Making dozens of sorties a day for several months.

Helitack is the use of helicopters to combat wildland fires.

The helicopters are used for aerial firefighting,

Water bombing,

And may be fitted with tanks or carry helibuckets.

Helibuckets such as the Bambi bucket are usually filled by submerging the bucket into lakes,

Rivers,

Reservoirs,

Or portable tanks.

Tanks fitted onto helicopters are filled from a hose while the helicopter is on the ground,

Or water is siphoned from lakes or reservoirs through a hanging snorkel as the helicopter hovers over the water source.

Helitack helicopters are also used to deliver firefighters who rappel down to inaccessible areas and to resupply firefighters.

Common firefighting helicopters include variants of the Bell 205 and the Ericsson S-64 air crane helitanker.

Helicopters are used as air ambulances for emergency medical assistance in situations when an ambulance cannot easily or quickly reach the scene,

Or cannot transport the patient to a medical facility in time.

Helicopters are also used when patients need to be transported between medical facilities,

And air transportation is the most practical method.

An air ambulance helicopter is equipped to stabilize and provide limited medical treatment to a patient while in flight.

The use of helicopters as air ambulances is often referred to as medevac,

And patients are referred to as being airlifted or medevac.

This use was pioneered in the Korean War,

When time to reach a medical facility was reduced to three hours from the eight hours needed in World War II,

And further reduced to two hours by the Vietnam War.

In naval service,

A prime function of rescue helicopters is to promptly retrieve downed aircrew involved in crashes occurring upon launch or recovery aboard aircraft carriers.

In past years,

This function was performed by destroyers escorting the carrier,

But since then helicopters have proved vastly more effective.

Police departments and other law enforcement agencies use helicopters to pursue suspects and patrol the skies.

Since helicopters can achieve a unique aerial view,

They are often used in conjunction with police on the ground to report on suspects' locations and movements.

They are often mounted with lighting and heat-sensing equipment for night pursuits.

Military forces use attack helicopters to conduct aerial attacks on ground targets.

Such helicopters are mounted with missile launchers and miniguns.

Transport helicopters are used to ferry troops and supplies where the lack of an airstrip would make transport via fixed-wing aircraft impossible.

The use of transport helicopters to deliver troops as an attack force on an objective is referred to as air assault.

UAS helicopter systems of varying sizes are developed by companies for military reconnaissance and surveillance duties.

Naval forces also use helicopters equipped with dipping sonar for anti-submarine warfare since they can operate from small ships.

Oil companies charter helicopters to move workers and parts quickly to remote drilling sites located at sea or in remote locations.

The speed advantage over boats makes the high operating cost of helicopters cost-effective in ensuring that oil platforms continue to operate.

Various companies specialize in this type of operation.

NASA developed Ingenuity,

A 1.

8-kilogram helicopter used to survey Mars along with a rover.

It began service in February 2021.

As the Martian atmosphere is 100 times thinner than Earth's,

Its two blades spin at close to 3,

000 revolutions a minute,

Approximately 10 times faster than that of a terrestrial helicopter.

Market In 2017,

926 civil helicopters were shipped for $3.

68 billion,

Led by Airbus helicopters with $1.

87 billion for 369 rotorcraft,

Leonardo helicopters with $806 million for 102,

First three-quarters only,

Bell helicopter with $696 million for 132,

Then Robinson helicopter with $161 million for 305.

By October 2018,

The in-service and stored helicopter fleet of 38,

570 with civil or government operators was led by Robinson helicopter with 24.

7 percent,

Followed by Airbus helicopters with 24.

4 percent.

Then Bell with 20.

5 and Leonardo with 8.

4 percent.

Russian helicopters with 7.

7 percent,

Sikorsky aircraft with 7.

2 percent,

MD helicopters with 3.

4 percent,

And other with 2.

2 percent.

The most widespread model is the Piston Robinson R-44 with 5,

600,

Then the H-125 AS-350 with 3,

600 units,

Followed by the Bell 206 with 3,

400.

Most were in North America with 34.

3 percent,

Then in Europe with 28 percent,

Followed by Asia Pacific with 18.

6 percent,

Latin America with 11.

6 percent,

Africa with 5.

3 percent,

And Middle East with 1.

7 percent.

History Early Design One of the earliest references for vertical flight came from China.

Since around 400 BC,

Chinese children have played with bamboo flying toys or Chinese top.

This bamboo copter is spun by rolling a stick attached to a rotor.

The spinning creates lift and the toy flies when released.

The 4th century AD Taoist book Bapuzi by J.

Hong reportedly describes some of the ideas inherent to rotary wing aircraft.

Designs similar to the Chinese helicopter toy appeared in some Renaissance paintings and other works.

In the 18th and early 19th centuries,

Western scientists developed flying machines based on the Chinese toy.

It was not until the early 1480s when Italian polymath Leonardo da Vinci created a design for a machine that could be described as an aerial screw that any recorded advancement was made towards vertical flight.

His notes suggested that he built small flying models,

But there were no indications for any provision to stop the rotor from making the craft rotate.

As scientific knowledge increased and became more accepted,

People continued to pursue the idea of vertical flight.

In July 1754,

Russian Mikhail Lomonosov had developed a small coaxial model after the Chinese top,

But powered by a wound-up spring device,

And demonstrated it to the Russian Academy of Sciences.

It was powered by a spring and was suggested as a method to lift meteorological instruments.

In 1783,

Christian de Lannoy and his mechanic Bienvenu used a coaxial version of the Chinese top in a model consisting of contra-rotating turkey flight feathers as rotator blades.

And in 1784,

Demonstrated it to the French Academy of Sciences.

Sir George Cayley,

Influenced by a childhood fascination with the Chinese flying top,

Developed a model of feathers similar to that of Lannoy and Bienvenu,

But powered by rubber bands.

By the end of the century,

He had progressed to using sheets of tin for rotor blades and springs for power.

His writings on his experiments and models would become influential on future aviation pioneers.

Alphonse Penault would later develop coaxial rotor model helicopter toys in 1870,

Also powered by rubber bands.

One of these toys,

Given as a gift by their father,

Would inspire the Wright brothers to pursue the dream of flight.

In 1861,

The word helicopter was coined by Gustave de Ponton de Mercot,

A French inventor who demonstrated a small steam-powered model.

While celebrated as an innovative use of new metal,

Aluminum,

The model never lifted off the ground.

De Mercot's linguistic contribution would survive to eventually describe the vertical flight he had envisioned.

Steam power was popular with other inventors as well.

In 1878,

The Italian Enrico Forlanini's unmanned vehicle,

Also powered by a steam engine,

Rose to a height of 12 meters,

39 feet,

Where it hovered for some 20 seconds after a vertical takeoff.

Emmanuel Duod's steam-powered design featured counter-rotating rotors powered through a hose from a boiler on the ground.

In 1887,

Parisian inventor Gustave Trouvé built and flew a tethered electric model helicopter.

In July 1901,

The maiden flight of Hermann Gonswain's helicopter took place in Berlin-Schönberg.

This was probably the first heavier-than-air motor-driven flight carrying humans.

A movie covering the event was taken by Max Gladonowski,

But it remains lost.

In 1885,

Thomas Edison was given $1,

000 U.

S.

Dollars,

Equivalent to $30,

000 today,

By James Gordon Bennett Jr.

To conduct experiments towards developing flight.

Edison built a helicopter and used the paper for a stock ticker to create gun cotton,

With which he attempted to power an internal combustion engine.

The helicopter was damaged by explosions,

And one of his workers was badly burned.

Edison reported that it would take a motor with a ratio of 3 to 4 pounds per horsepower produced to be successful,

Based on his experiments.

Jan Bajel,

A Slovak inventor,

Adapted the internal combustion engine to power his helicopter model that reached a height of 0.

5 meters in 1901.

On the 5th of May 1905,

His helicopter reached 4 meters in altitude and flew for over 1,

500 meters.

In 1908,

Edison patented his own design for a helicopter powered by a gasoline engine,

With box kites attached to a mast by cables for a rotor.

But it never flew.

First Flights In 1906,

Two French brothers,

Jacques and Louis Breguet,

Began experimenting with the airfoils for helicopters.

In 1907,

Those experiments resulted in the Gyroplane No.

1,

Possibly as the earliest known example of a quadcopter.

Although there is some uncertainty about the date,

Sometime between the 14th of August and the 29th of September 1907,

The Gyroplane No.

1 lifted its pilot into the air about 0.

6 meters for a minute.

The Gyroplane No.

1 proved to be extremely unsteady and required a man at each corner of the airframe to hold it steady.

For this reason,

The flights of the Gyroplane No.

1 are considered to be the first manned flight of a helicopter,

But not a free or untethered flight.

That same year,

Fellow French inventor Paul Cornu designed and built the Cornu helicopter,

Which used two 6.

1 meter counter-rotating rotors driven by a 24 horsepower Antoinette engine.

On the 13th of November 1907,

It lifted its inventor to 0.

3 meters and remained aloft for 20 seconds.

Even though this flight did not surpass the flight of the Gyroplane No.

1,

It was reported to be the first truly free flight with a pilot.

Cornu's helicopter completed a few more flights and achieved a height of nearly 2 meters,

But it proved to be unstable and was abandoned.

In 1909,

J.

Newton Williams of Derby,

Connecticut and Emil Berliner of Washington,

D.

C.

Flew a helicopter on three occasions at Berliner's lab in Washington's Brightwood neighborhood.

In 1911,

Slovenian philosopher and economist Ivan Slokar patented a helicopter configuration.

The Danish inventor Jacob Elahammer built the Elahammer helicopter in 1912.

It consisted of a frame equipped with two counter-rotating discs,

Each of which was fitted with six vanes around its circumference.

After indoor tests,

The aircraft was demonstrated outdoors and made several free takeoffs.

Experiments with the helicopter continued until September 1916,

When it tipped over during takeoff,

Destroying its rotors.

During World War I,

Austria-Hungary developed the PKZ.

An experimental helicopter prototype was to aircraft build.

Reviews

I’ve tried to listen twice and I there is still much I don’t know about helicopters.

Excellent reading and definitely boring! The first five minutes were interesting but that was it! 😂😂

Thank you! 🥰🥰