From Wikipedia, the free encyclopedia
.^ These helicopters are different from the A-stars in that they have bucket seats, even more viewing glass area and a quieter engine so it is not heard so easily from the ground.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
.^ There is a refreshing lack of restrictions of flying and landing helicopters within Panama.
^ I have held a commercial fixed wing (light aircraft) in both NZ and Australia but both are lapsed some years now.
^ I can take off from a bar stool, fly around the room, hover over my head and land in the palm of my hand.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
.^ I have held a commercial fixed wing (light aircraft) in both NZ and Australia but both are lapsed some years now.
^ I can take off from a bar stool, fly around the room, hover over my head and land in the palm of my hand.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
^ These helicopters are different from the A-stars in that they have bucket seats, even more viewing glass area and a quieter engine so it is not heard so easily from the ground.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
.^ I have held a commercial fixed wing (light aircraft) in both NZ and Australia but both are lapsed some years now.
^ My fixed wing experience allowed me to concentrate more on actually flying the aircraft as opposed to trying to take in instruments, radio etc.
^ FAR 91.119 says "Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes..."
The word 'helicopter' is adapted from the
French
hélicoptère, coined by Gustave de Ponton d'Amecourt in
1861, which originates from the Greek
helix/helik- (
ἕλικ-) = 'spiral' or 'turning' and
pteron (
πτερόν) =
'wing'.
[1][2].^ When they first came they flew the Robinson R44 aircraft which was an excellent tour for people who wanted private flights for just 2 in a helicopter.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
^ While helicopter flight school instruction is one aspect of our program, we emphasize professional development to make our customers employable.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ For $1000, you can buy a full size RC heli and crash it hard the first flight and game over!- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
[4]
.^ The McDonnell-Douglas Notar is designed without a tail rotor, giving a noticeably quieter flight.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
^ Keep in mind however that you won't be seeing anything different than you would in the A-Star but perhaps in a bit more deluxe manner.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
^ You'd expect helicopters to be vastly more dangerous than airplanes.
History
The earliest references for vertical flight have come from
China. Since 400 BC,
[5] Chinese children have played with
bamboo flying
toys[6][7]
and a book written in 4th-century China, referred to as
Pao Phu
Tau (also
Pao Phu Tzu or
Bao Pu Zi,
抱朴子), is reported to describe some of the
ideas inherent to rotary wing aircraft:
[8]
|
“ |
Someone asked the master
about the principles of mounting to dangerous heights and traveling
into the vast inane. The Master said, "Some have made flying cars
with wood from the inner part of the jujube tree, using ox-leather [straps] fastened
to returning blades so as to set the machine in motion."[9] |
” |
da Vinci's "aerial screw"
It was not until the early 1480s, when
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.
.^ Old school helicopter pilots will scoff at the R22 for a variety of reasons, including the low inertia rotor system, but there is no low-cost alternative.
^ Mind that this tweak will make flying backwards even more unstable than it already is, because even more air will be blown into the main rotor.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
^ The rotator shaft does not come between the front and back seats and there are no visual impediments interrupting your view forward.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
[10][11]
As scientific knowledge increased and became more accepted, men
continued to pursue the idea of vertical flight.
.^ Keep in mind however that you won't be seeing anything different than you would in the A-Star but perhaps in a bit more deluxe manner.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
^ This is a much closer look than you would get in a commercial airliner, but it isn't all that close.
^ My fixed wing experience allowed me to concentrate more on actually flying the aircraft as opposed to trying to take in instruments, radio etc.
In July 1754,
Mikhail Lomonosov demonstrated a
small coaxial rotor to the
Russian Academy of
Sciences. It was powered by a spring and suggested as a method
to lift
meteorological instruments. In 1783,
Christian de Launoy, and his
mechanic, Bienvenu, made a model with a pair
of counter-rotating rotors, using
turkey's flight feathers as rotor 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, grew up to
develop a model of feathers, similar to Launoy 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.
[10]
Alphonse
Pénaud 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.
[12].^ Big jet-powered helicopters are safer than small airplanes, but not by the huge factor that big jet-powered airplanes are safer.
.^ I’ve tried Testor’s plastic model glue, but after one or two runs, the glue just “lifts off” the blades.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
D'Amecourt's linguistic contribution would survive
to eventually describe the vertical flight he had envisioned. Steam
power was popular with other inventors as well.
.^ In a turbine-powered helicopter like a Bell 206 JetRangers the blades are heavy and the blades won't slow down for several seconds after an engine failure.
.^ If the pilot takes his hands off the controls, the plane will fly itself for 30 seconds (or 3 hours if typically equipped with an autopilot).
Dandrieux's
design had counter-rotating rotors and a 7.7-pound (3.5-kilogram)
steam engine. It rose more than 40 feet (12 m) and flew for 20
seconds circa 1878.
[10]
In 1885,
Thomas
Edison was given US$1,000 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
guncotton, 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 three to four pounds per
horsepower produced to be successful, based on his experiments.
[13] .^ An R22 loses power at higher altitudes because its engine is not turbocharged.
^ In a turbine-powered helicopter like a Bell 206 JetRangers the blades are heavy and the blades won't slow down for several seconds after an engine failure.
^ Piston-powered helicopters, which these days means "Robinson", suffer 13-20 accidents per year, with roughly 2 of those accidents being fatal.
[14] .^ I my Micro Mosquito in early June 2007 and I must say that it is THE best multi rotor helicopter I have ever owned!.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
[15]First
flights
Paul Cornu's helicopter in 1907
In 1906, two French brothers, Jacques and
Louis Breguet, began experimenting with
airfoils for helicopters and in 1907, those experiments resulted in
the
Gyroplane No.1. Although there is some uncertainty
about the dates, sometime between 14 August and 29 September 1907,
the Gyroplane No.
.^ Within a minute of starting up, I had control of one control, gradually moving up to all controls within about another minute or so!
^ The two professional pilots up front and the superbly capable equipment make flying an airplane seem easy.
^ Before you get into the air you'll probably spend about half an hour on a preflight inspection of the helicopter.
[3]
However, 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.
Hungarian "PKZ" military helicopter (
Ganz Company 1916)
.^ Schweizer, for example, which bought the old Hughes design, manufactures a comparative handful of piston-engine helicopters each year.
^ The same person has very likely only been on one or two helicopter rides in his life.
^ The net result of using an aerodiesel engine could be a helicopter with longer range and much better performance in the mountains.
On 13
November 1907, it lifted its inventor to 1 foot (0.3 m) and
remained aloft for 20 seconds.
.^ At no time did he lose control of the machine, even hover taxiing back to the parking spot.
1, it was reported to be
the first truly free flight with a pilot.
[n
. Cornu's helicopter would complete a few
more flights and achieve a height of nearly 6.5 feet (2 m), but it
proved to be unstable and was abandoned.
^ Request Information: Take the next step in your helicopter training by contacting our featured helicopter flight schools for more info.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ Complete Helicopters is proud to offer top quality helicopter flight school instruction at reasonable prices.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ Helicopters are unstable and very few are equipped with autopilots.
[3]
During the World War I in 1917, the engineers of Hungarian
Ganz Company designed a radical
motorized flying machine to replace the dangerous hydrogen-filled
balloons then being used to observe enemy positions. The P.K.Z.
aircraft flew to a height of over 50 m. It was supported by 120 hp
engines and two massive wooden propellers turning in opposite
directions. It was intended to lift a pilot, observer, machine gun
and fuel for an hour's flight.
[16]
.^ Utah Helicopter - Montana You can follow many exciting and lucrative paths in the world of rotor-wing aviation.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ Utah Helicopter - Salt Lake City, Utah You can follow many exciting and lucrative paths in the world of rotor-wing aviation.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ Utah Helicopter - Wyoming You can follow many exciting and lucrative paths in the world of rotor-wing aviation.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
[17]Early
development
In the early 1920s, Argentine
Raúl
Pateras Pescara, while working in Europe, demonstrated one of
the first successful applications of cyclic pitch.
[3]
.^ I discovered that I could deliver more forward power to the tail rotor and increase motor speed from inside the transmitter.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
The rotor
hub could also be tilted forward a few degrees, allowing the
aircraft to move forward without a separate propeller to push or
pull it.
.^ As long as the helicopter could autorotate to a tennis court, road, or field in the event of an engine failure, the pilot can fly much lower than in an airplane.
^ (In practice the cyclic flare is more important than the "hovering autorotation" at the end; a lot of people walk away from helicopter engine failures if they get the cyclic flare right but can't manage to pull the collective smoothly at the last moment.
^ In a turbine-powered helicopter like a Bell 206 JetRangers the blades are heavy and the blades won't slow down for several seconds after an engine failure.
By January
1924, Pescara's helicopter No.
.^ Or we load up four people and full fuel and fly to a Manhattan heliport in 1 hour 45 minutes from Boston.
.^ Learning to fly helicopters is one of life’s most rewarding adventures!- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ Blaine, Minnesota Our Private Pilot Training Program is your first step in enjoying all the excitement and privileges of helicopter flying.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ If you are training at a school with only one helicopter and one instructor, the risk of being unable to fly is very high.
.^ I taught a U.S. Navy airplane pilot to fly and hover a helicopter in about twenty minutes.
[18]
Not to be outdone, Oehmichen reclaimed the world record on 4 May
when he flew his No. 2 machine again for a 14-minute flight
covering 5,550 feet (1.05 mi, 1.69 km) while climbing to
a height of 50 feet (15 m).
[18]
Oehmichen also set the 1 km closed-circuit record at 7 minutes
40 seconds.
[3]
Meanwhile,
Juan de la Cierva was developing the
first practical rotorcraft in Spain.
.^ At C-R Helicopters, custom designed, FAA approved courses take you from entry level to the most advanced qualification possible.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
^ Helicopter Tours and Rides in Maui - Without a doubt the single most spectacular activity you can take on Maui would be a helicopter flight.- Maui Helicopter Tour in Maui Hawaii Helicopters Tours Rides 7 January 2010 13:56 UTC www.tombarefoot.com [Source type: General]
^ Baker Aircraft - Baker City, Oregon Baker Aircraft is offering a helicopter flight school with an accelerated 2 week private pilot training program in our rotor wing aircraft.- Helicopter Training and Helicopter Flight Schools Directory - Helicopter-Training.net 7 January 2010 13:56 UTC www.helicopter-training.net [Source type: General]
.^ A three-channel digital remote controls up & down motion, forward & reverse, turning left & right and even allows the Mosquito to hover.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
A crash in 1927, led to the development
of a drag hinge to relieve further stress on the rotor from its
flapping motion.
[19]
.^ A three-channel digital remote controls up & down motion, forward & reverse, turning left & right and even allows the Mosquito to hover.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
Albert Gillis von Baumhauer, a Dutch aeronautical engineer,
began studying rotorcraft design in 1923. His first prototype
"flew" ("hopped" and hovered in reality) on 24 September 1925, with
Dutch Army-Air arm Captain Floris Albert van Heijst at the
controls.
.^ Then you take the collective while the instructor controls the cyclic and pedals.
Patents were granted to von Baumhauer for his cyclic and collective
controls by the British ministry of aviation on 31 January 1927,
under patent number 265,272.
In 1930, the Italian engineer
Corradino D'Ascanio built his
D'AT3, a coaxial helicopter. His relatively large machine had two,
two-bladed, counter-rotating rotors.
.^ I am going to try taking mine back – despite using the trim control and following the troubleshooting directions, bending every rotor blade, the helicopter will not stop spinning right.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
^ It has more controllability then any other mini RC helicopter I’ve ever flown.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
Three small propellers mounted to the
airframe were used for additional pitch, roll, and yaw control. The
D'AT3 held modest FAI speed and altitude records for the time,
including altitude (18 m or 59 ft), duration (8 minutes
45 seconds) and distance flown (1,078 m or 3,540 ft).
[20].^ The tail rotor is counterbalancing engine torque but at the same time is pushing the machine to the right.
^ Work on using the pedals and cyclic so that the helicopter is neither yawing nor drifting when it hits the pavement.
^ The third tweak was increasing the tail rotor surface by sticking a few layers of scotch tape to the blades, and cutting them into a nice symmetrical ‘rotor’ shape.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
Powered by two M-2 powerplants, themselves
up-rated Soviet copies of the
Gnome Monosoupape rotary radial
engine of World War I, the TsAGI 1-EA made several successful low
altitude flights, and by 14 August 1932 Cheremukhin managed to get
the 1-EA up to an unofficial altitude of 605 meters
(1,985 ft), shattering d'Ascanio's earlier achievement. As the
Soviet Union was not yet a member of the
FAI, however,
Cheremukhin's record remained unrecognized.
[21][22]
.^ The tail rotor is counterbalancing engine torque but at the same time is pushing the machine to the right.
It flew in
Sint-Genesius-Rode, at the
Laboratoire Aérotechnique de Belgique (now
von Karman Institute) in April 1933, and
attained an altitude of six meters (20 ft) and an endurance of
eight minutes.
.^ A co-worker thought it would be funny and shot the skeeter out of the air with a spring metal paper holder and tore one of the rotors.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
.^ The main rotor hinges are so flexible that they will counter any attempt at tilting them.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
Using hingeless rotors and co-rotation also
minimised the stress on the hull. At the time, it was probably the
most stable helicopter in existence.
[23][24]
.^ Nonetheless, pilots of small aircraft managed to crash roughly 7 times in every 100,000 hours; 1.4 out of those 7 times, the accident was fatal.
^ I used some clear packing tape (the scotch tape I used at first was too flimsy and wouldn’t last) and repaired it and it works perfect – no difference in flight controls .- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
^ Experience with a particular aircraft or "time in type" is a huge contributor to safety; nothing stops a pilot from bringing an instructor along for the first 100 hours in a new aircraft.
On 14
December 1935, he set a record for closed-circuit flight with a
500-meter (1,600 ft) diameter. The next year, on 26 September
1936, Claisse set a height record of 158 meters (520 ft).
.^ One of my long-ago instructors neglected to perform a proper pre-flight inspection and plowed in, taking the mechanic with him.
^ One second after that the helicopter has responded to two seconds of continuous pressure by rushing backwards at a frightening clip.
The aircraft was destroyed in 1943 by an
Allied airstrike at
Villacoublay airport.
Birth of an
industry
First airmail service by helicopter in
Los Angeles, 1947
Despite the success of the
Gyroplane Laboratoire, the
German
Focke-Wulf Fw 61, first flown in 1936,
would eclipse its accomplishments.
.^ Flight schools, however, were quick to notice that the R22 was the world's cheapest helicopter to operate and began snapping them up.
^ Going from airport to airport in a well-maintained helicopter is not actually all that challenging or risky, but to the general public it is miraculous that such a flight is ever completed.
In February
1938,
Hanna
Reitsch became the first female helicopter pilot, exhibiting
the Fw 61 before crowds in the
Deutschlandhalle.
.^ If Schweizer were to cease producing and supporting civilian helicopters it would probably result in a revenue boost for Sikorsky because the people and workshops could be transferred to military contracts.
Prior to the war, LePage had received the patent rights
to develop helicopters patterned after the Fw 61, and built the
XR-1.
[25]
Meanwhile, Sikorsky had settled on a simpler, single rotor design,
the
VS-300. After experimenting with
configurations to counteract the torque produced by the single main
rotor, he settled on a single, smaller rotor mounted vertically on
the tailboom.
.^ Experience with a particular aircraft or "time in type" is a huge contributor to safety; nothing stops a pilot from bringing an instructor along for the first 100 hours in a new aircraft.
.^ If you are training at a school with only one helicopter and one instructor, the risk of being unable to fly is very high.
^ If, on the other hand, you get your helicopter instrument rating at 249 hours and your CFII-H at 250 hours, you only need to get sharp once.
Total production would reach 131 helicopters
before the R-4 was replaced by other Sikorsky helicopters such as
the
R-5 and the
R-6. In all, Sikorsky would produce over 400 helicopters before the
end of World War II.
[26]
.^ Finally you raise the collective as the helicopter falls, using the stored energy in the blades against the force of gravity.
^ I believe the main problem with the design is that the helicopter is too damn good at stabilizing itself.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
^ I am going to try taking mine back – despite using the trim control and following the troubleshooting directions, bending every rotor blade, the helicopter will not stop spinning right.- Micro Mosquito helicopter takes to the tiny skies - SlashGear 7 January 2010 13:56 UTC www.slashgear.com [Source type: FILTERED WITH BAYES]
The subsequent Model 30 helicopter
demonstrated the simplicity and ease of the design. The Model 30
was developed into the
Bell
47, which became the first helicopter certificated for civilian
use in the United States.
.^ In a turbine-powered helicopter like a Bell 206 JetRangers the blades are heavy and the blades won't slow down for several seconds after an engine failure.
Turbine
age
In 1951, at the urging of his contacts at the Department of the
Navy,
Charles
Kaman modified his
K-225 helicopter with a new kind of engine,
the
turboshaft engine.
This adaptation of the turbine engine provided a large amount of
power to the helicopter with a lower weight penalty than piston
engines, with their heavy engine blocks and auxiliary components.
On 11 December 1951, the
Kaman K-225 became the first
turbine-powered helicopter in the world. Two years later, on 26
March 1954, a modified Navy HTK-1, another Kaman helicopter, became
the first twin-turbine helicopter to fly. However, it was the
Sud Aviation Alouette II that would become
the first helicopter to be produced with a turbine-engine.
[27]Reliable helicopters capable of stable hover flight were
developed decades after fixed-wing aircraft. This is largely due to
higher engine power density requirements than fixed-wing aircraft.
Improvements in fuels and engines during the first half of the 20th
century were a critical factor in helicopter development. The
availability of lightweight
turboshaft engines in the second half of the
20th century led to the development of larger, faster, and
higher-performance helicopters. While smaller and less expensive
helicopters still use piston engines, turboshaft engines are the
preferred powerplant for helicopters today.
Uses
Due to the operating characteristics of the helicopter—its
ability to takeoff and land vertically, and to hover for extended
periods of time, as well as the aircraft's handling properties
under low
airspeed
conditions—it has been chosen 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, construction, firefighting, search and rescue, and
military uses.
|
|
Kern County (California) Fire Department Bell 205 dropping water on fire
|
|
|
|
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
the 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.
[28] These
operations are referred to as longline because of the long, single
sling line used to carry the load.
[29]Helitack is the use of
helicopters to combat
wildland
fires.
[30]
The helicopters are used for
aerial firefighting (or 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
Erickson S-64 Aircrane helitanker.
Helicopters are used as
air ambulances for emergency medical
assistance in situations when an
ambulance cannot easily or quickly reach the
scene. Helicopters are also used when a patient needs to be
transported between medical facilities and air transportation is
the most practical method for the safety of the patient. Air
ambulance helicopters are equipped to provide medical treatment to
a patient while in flight. The use of helicopters as an air
ambulance is often referred to as
MEDEVAC, and patients are
referred to as being "airlifted", or "medevaced".
Police departments and other law enforcement agencies
use helicopters
to pursue suspects. 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.
Oil companies charter helicopters to move workers and parts
quickly to remote drilling sites located out to sea or in remote
locations. The speed over boats makes the high operating cost of
helicopters cost effective to ensure that oil platforms continue to
flow. Companies such as
CHC Helicopter,
Bristow
Helicopters, and Air Logistics specialize in this type of
operation.
Other uses of helicopters include, but are not limited to:
Design
features
Basic anatomy of a Helicopter
Rotor
system
The rotor system, or more simply
rotor, is the rotating
part of a helicopter which 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 lift
horizontally as thrust to counteract torque effect. The rotor
consists of a mast, hub and rotor blades.
The mast is a cylindrical metal shaft which extends
upwards from and is driven by the transmission. At the top of the
mast is the attachment point for the rotor blades called the
hub. The rotor blades are then attached to the hub by a
number of different methods. Main rotor systems are classified
according to how the main rotor blades are attached and move
relative to the main rotor hub. There are three basic
classifications: rigid, semirigid, or fully articulated, although
some modern rotor systems use an engineered combination of these
types.
Antitorque
configurations
MD Helicopters 520N NOTAR
Most helicopters have a single main rotor, but torque created as
the engine turns the rotor against its air drag causes the body of
the helicopter to turn in the opposite direction to the rotor. To
eliminate this effect, some sort of antitorque control must be
used. The design that
Igor Sikorsky settled on for his
VS-300 was a smaller rotor mounted
vertically on the tail. The tail rotor pushes or pulls against the
tail to counter the torque effect, and has become the recognized
convention for helicopter design. Some helicopters utilize
alternate antitorque controls in place of the tail rotor, such as
the
ducted fan (called
Fenestron or
FANTAIL), and
NOTAR.
NOTAR provides antitorque similar to the way a wing develops lift,
through the use of a
Coandă effect on the tailboom.
[31]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 antitorque tail
rotor. This allows the power normally required to drive the tail
rotor to be applied to the main rotors, increasing the aircraft's
lifting capacity. Primarily, there are three common configurations
that use the counterrotating effect to benefit the rotorcraft.
Tandem rotors are
two rotors with one mounted behind the other.
Coaxial rotors
are two rotors that are mounted one above the other with the same
axis.
Intermeshing rotors are two rotors
that are mounted close to each other at a sufficient angle to allow
the rotors to intermesh over the top of the aircraft. Transverse
rotors is another configuration found on
tiltrotors and some earlier helicopters,
where the pair of rotors are mounted at each end of the wings or
outrigger structures.
Tip
jet designs permit the rotor to push itself through the air,
and avoid generating torque.
Engines
The number, size and type of engine 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 the amount of power produced by
an engine was not able to overcome the engine's weight in vertical
flight. 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
powerplant easily adapted to small helicopters, although radial
engines continued to be used for lager helicopters.
Turbine engines revolutionized the aviation industry, and the
turboshaft engine finally
gave helicopters an engine with a large amount of power and a low
weight penalty. 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 combustion exhaust are
referred to as hot tip jets. An example of a cold jet helicopter is
the
Sud-Ouest
Djinn, and an example of the hot tip jet helicopter is the
YH-32 Hornet.
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. Although, the
Robinson R22 and
Robinson R44 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 the
pitch of the rotor
blades cyclically. The result is to tilt the rotor disk in a
particular direction, resulting in the helicopter moving in that
direction. If the pilot pushes the cyclic forward, the rotor disk
tilts forward, and the rotor produces a thrust in the forward
direction. If the pilot pushes the cyclic to the side, the rotor
disk 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 blades 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 the helicopter increasing or decreasing in altitude.
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 at a specific RPM. The
throttle controls the power produced by the engine, which is
connected to the rotor by a transmission. The purpose of the
throttle is to maintain enough engine power to keep the rotor RPM
within allowable limits in order to keep the rotor producing 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 lever for each
engine.
A
Swashplate transmits the pilot
commands to the main rotor blades for articulated rotors.
Flight
conditions
There are two basic flight conditions for a helicopter; hover
and forward
flight.
- 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 end
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.
- In forward flight a helicopter's flight controls behave more
like that in a fixed-wing aircraft. Displacing the cyclic forward
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 in 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.
Safety
Limitations
RAN Squirrel helicopters during a
display at the 2008 Melbourne Grand Prix
.^ Helicopters are particularly suited to searching for lost people due to their slow hovering speed and ability to fly low to the ground.- RACQ Capricorn Helicopter Rescue 7 January 2010 13:56 UTC www.chrs.org.au [Source type: News]
^ The question was "What are three limitations to forward speed in helicopter flight" and the answer "The blades fall off!"- Chinook Helicopters - Helicopter Pilot Training 7 January 2010 13:56 UTC chinookhelicopters.com [Source type: General]
^ Conventional helicopters are incredibly useful vehicles in many short-range scenarios - but their asymmetrical aerodynamics enforce a fairly low terminal speed limit of around 150mph, making them less than ideal for longer-range missions.- Helicopters - Gizmag Tag 7 January 2010 13:56 UTC www.gizmag.com [Source type: General]
There
are several reasons why a helicopter cannot fly as fast as a fixed
wing aircraft. When the helicopter is hovering, the outer tips of
the rotor travel at a speed determined by the length of the blade
and the RPM. In a moving helicopter, however, the speed of the
blades relative to the air depends on the speed of the helicopter
as well as on their rotational velocity. The airspeed of the
advancing rotor blade is much higher than that of the helicopter
itself. It is possible for this blade to exceed the
speed of sound,
and thus produce vastly increased drag and vibration. See
Wave drag.
Because the advancing blade has higher airspeed than the
retreating blade and generates a
dissymmetry of lift, rotor blades
are designed to "flap" – lift and twist in such a way that the
advancing blade flaps up and develops a smaller angle of attack.
Conversely, the retreating blade flaps down, develops a higher
angle of attack, and generates more lift. At high speeds, the force
on the rotors is such that they "flap" excessively and the
retreating blade can reach too high an angle and stall. For this
reason, the maximum safe forward airspeed of a helicopter is given
a design rating called
VNE,
Velocity, Never
Exceed.
[34] In
addition, at extremely high speeds, it is possible for the
helicopter to travel faster than the retreating blade which would
inevitably stall the blade, regardless of the angle of attack.
During the closing years of the 20th century designers began
working on
helicopter noise reduction.
Urban communities have often expressed great dislike of noisy
aircraft, and police and passenger helicopters can be unpopular.
The redesigns followed the closure of some city heliports and
government action to constrain flight paths in
national parks and other places of natural
beauty.
Helicopters also vibrate; an unadjusted helicopter can easily
vibrate so much that it will shake itself apart. To reduce
vibration, all helicopters have rotor adjustments for height and
weight. Blade height is adjusted by changing the pitch of the
blade. Weight is adjusted by adding or removing weights on the
rotor head and/or at the blade end caps. Most also have vibration
dampers for height and pitch. Some also use mechanical feedback
systems to sense and counter vibration. Usually the feedback system
uses a mass as a "stable reference" and a linkage from the mass
operates a flap to adjust the rotor's
angle of attack to counter the
vibration. Adjustment is difficult in part because measurement of
the vibration is hard, usually requiring sophisticated
accelerometers mounted throughout the airframe and gearboxes. The
most common blade vibration adjustment measurement system is to use
a stroboscopic flash lamp, and observe painted markings or coloured
reflectors on the underside of the rotor blades. The traditional
low-tech system is to mount coloured chalk on the rotor tips, and
see how they mark a linen sheet. Gearbox vibration most often
requires a gearbox overhaul or replacement. Gearbox or drive train
vibrations can be extremely harmful to a pilot. The most severe
being pain, numbness, loss of tactile discrimination and
dexterity.
Hazards
As with any moving vehicle, unsafe operation could result in
loss of control, structural damage, or fatality. The following is a
list of some of the potential hazards for helicopters:
- Settling with power, also known as
a vortex ring state,
is when the aircraft is unable to arrest its descent due to the
rotor's downwash interfering with the aerodynamics of the
rotor.
- Retreating blade stall is
experienced during high speed flight and is the most common
limiting factor of a helicopter's forward speed.
- Ground
resonance affects helicopters with fully articulated rotor
systems having a natural lead-lag frequency less than the blade
rotation frequency.
- Low-G condition affects helicopters with
two-bladed main rotors, particularly lightweight helicopters.
- Dynamic
rollover in which the helicopter pivots around one of the skids
and 'pulls' itself onto its side.
- Powertrain
failures, especially those that occur within the shaded area of the
height-velocity diagram.
- Tail rotor failures which occur from either a mechanical
malfunction of the tail rotor control system or a loss of tail
rotor thrust authority, called Loss of Tail-rotor Effectiveness
(LTE).
- Brownout in dusty conditions or whiteout
in snowy conditions.
- Low Rotor RPM, or rotor droop, in which the engine
cannot drive the blades at sufficient RPM to maintain flight.
- Wire and tree strikes due to low altitude operations and
take-offs and landings in remote locations.[35]
Deadliest
crashes
- 2002 Khankala Mi-26 crash: Mi-26 shot down
over Chechnya in 2002; 127
killed.
- 1997 Israeli helicopter
disaster: MH-53 crash in Israel in 1997; 73
killed.
- 1977 Israeli CH-53 crash: CH-53 crash
near Yitav in the Jordan Valley on 10
May 1977; 54 killed.
- September 11, 1982, at an airshow in Mannheim, Germany a United
States Army Chinook (serial number 74-22292) crashed killing
46.[36][37]
- 1986
British International Helicopters Chinook crash: a British International
Helicopters Boeing 234LR Chinook crashed in the Shetland Islands; 45 killed.
- 2009 Pakistan Army Mil
Mi-17 crash: 41 killed.
- 26 January 2005: a CH-53E Super Stallion from HMH-361 crashed near Ar
Rutbah, Iraq killing all 31
service members onboard.[38]
See also
References
- Notes
- ^
Dr. J. Gordon Leishman, a Technical Fellow of AHS International, presented a paper at the
64th Annual Forum of the American Helicopter Society International,
on the aerodynamic capability of Cornu's design, arguing that the
aircraft lacked the power and rotor loading to lift free of the
ground in manned flight.
- Footnotes
- ^
"helicopter". Online
Etymology Dictionary. Retrieved: 28 November 2007
- ^
Cottez 1980, p. 181.
- ^ a
b
c
d
e
Munson 1968
- ^ Hirschberg, Michael
J. and David K. Dailey, "Sikorsky." US and Russian
Helicopter Development In the 20th Century. American
Helicopter Society, International. 7 July 2000.
- ^
Leishman, J. Gordon. Principles of Helicopter Aerodynamics.
Cambridge aerospace series, 18. Cambridge: Cambridge University Press,
2006. ISBN 9780521858601
- ^
"Early Helicopter
History". Aerospaceweb.org. Accessed on 1 November 2008.
- ^ Goebel, Greg. "The Invention Of The
Helicopter". Vectorsite.net. Retrieved: 11 November 2008.
- ^ Fay, John. "Helicopter Pioneers - Evolution of Rotary Wing
Aircraft". Helicopter History Site. Retrieved: 28 November
2007.
- ^
English, Dave, ed. "Predictions", Great
Aviation Quotes. Skygod.com. Retrieved: 9 December 2007.
- ^ a
b
c
Rumerman, Judy. "Early Helicopter
Technology". Centennial of Flight Commission. Accessed on 9
December 2007.
- ^ Pilotfriend.com
"Leonardo Da Vinci's Helical
Air Screw". Pilotfriend.com. Accessed on 28 November 2007.
- ^ Hallion, Richard P. "Pioneers of Flight: Alphonse
Pénaud". Air Force Link. Accessed on 1 November 2008.
- ^
Bryan, George S. Edison: the Man and His Work. Garden
City, New York: Garden City Publ., 1926. p. 249.
- ^
"Pioneers - 1900/1930".
Helicopter History Site. Retrieved: 3 May 2007.
- ^
Dowd, George L. "Flops of famous inventors". Popular
Science. December 1930.
- ^
http://www.aviastar.org/helicopters_eng/petroczy.php
- ^
http://www.aviapress.com/viewonekit.htm?ROD-008
- ^ a
b
Rumerman, Judy. "Helicopter Development in
the Early Twentieth Century". Centennial of Flight Commission.
Retrieved: 28 November 2007.
- ^ a
b
"The Contributions of the
Autogyro". Centennial of Flight Commission. Retrieved: 28
November 2007.
- ^ a
b
Spenser 1998
- ^
[1]
- ^
[2]
- ^ [3], Aviastar.
Retrieved: 26 June 2008
- ^ Watkinson 2004,
p. 358.
- ^ Francillon
1997
- ^ Day, Dwayne A. "Igor Sikorsky - VS 300".
Centennial of Flight Commission. Retrieved: 9 December 2007.
- ^ Connor, R.D. and R.E.
Lee. "Kaman K-225". Smithsonian
National Air and Space Museum. 27 July 2001. Retrieved: 9 December
2007.
- ^
Day, Dwayne A. "Skycranes". Centennial
of Flight Commission. Accessed on 1 October 2008.
- ^
Webster, L. F. The Wiley Dictionary of Civil Engineering and
Construction. New York: Wiley, 1997. ISBN 0-47118-115-3
- ^ Butler, Bret W., Roberta
A. Bartlette, Larry S. Bradshaw, Jack D. Cohen, Patricia L.
Andrews, Ted Putnam, and Richard J. Mangan. "Appendix A:Glossary".
Fire Behavior Associated with the 1994 South Canyon Fire on
Storm King Mountain, Colorado. research paper. U.S. Dept. of
Agriculture, Forest Service. September 1998. Accessed on 2 November
2008.
- ^ Frawley 2003, p.
151.
- ^
Rotomotion SR20 fact
sheet, Rotomotion.
- ^
Jay Leno's EcoJet
Concept
- ^
Rotorcraft Flying Handbook.
Washington: Skyhorse Publishing, Inc.. 2007. pp. 3–7. ISBN
1-60239-060-6.
- ^
Helicopter Accidents in
Hawaii
- ^
Chinook crash in
Mannheim
- ^
Crash Death, 3rd in 8 Years,
Not Expected to Halt Future Shows
- ^ "Incident Date 050126 HMH-361
CH-53D - BuNo unknown - incident not yet classified - near Ar
Rutbah, Iraq". Marine Corps Combat Helicopter Association. http://www.popasmoke.com/kia/incidents.php?incident_id=278&conflict_id=32. Retrieved
2007-11-20.
- Bibliography
- Chiles, James R. The God Machine: From Boomerangs to Black
Hawks: The Story of the Helicopter. New York: Bantam Books,
2007. ISBN 0553804472.
- Cottez, Henri. Dictionnaire des structures du vocabulaire
savant. Paris: Les Usuels du Robert. 1980. ISBN
0-851-77827-5.
- Flight Standards Service. Rotorcraft Flying Handbook: FAA
Manual H-8083-21. Washington, DC: Federal Aviation
Administration, U.S. Dept. of Transportation, 2001. ISBN
1-56027-404-2.
- Francillon, René J. McDonnell Douglas Aircraft since 1920:
Volume II. London: Putnam, 1997. ISBN 0-851-77827-5.
- Frawley, Gerard. The International Directory of Civil
Aircraft, 2003-2004. Fyshwick, Canberra, Act, Australia:
Aerospace Publications Pty Ltd., 2003, p. 155. ISBN
1-875671-58-7.
- Munson, Kenneth. Helicopters and other Rotorcraft since
1907. London: Blandford Publishing, 1968. ISBN
978-0-713-70493-8.
- Thicknesse, P. Military Rotorcraft (Brassey's World
Military Technology series). London: Brassey's, 2000. ISBN
1-857533-25-9.
- Watkinson, John. Art of the Helicopter. Oxford: Elsevier
Butterworth-Heinemann, 2004. ISBN 0750657154
- Wragg, David W. Helicopters at War: A Pictorial
History. London: R. Hale, 1983. ISBN 0-709-00858-9.
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