The My Delta Pi webstore
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Mail: aquila_grande@yahoo.no
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The My Delta Pi webstore
|
Back to main menu - hobby, automotive, fashion, watches, jewelry. health, electrionics
Mail: aquila_grande@yahoo.no |
|
RC helicopter models
Welcome to this online presentation of remote controle helicopter models - from affordable indoor models to advanced challenging acrobatic helicopters. By clicking on the banners for the presented products or online stores, you can learn more about the exhibited model and a lot of other models.
At the bottom of this page there is an article about RC helicopter technology.
To see more advanced helicopter and aircraft models - please click here and here
Good online shops where you can
find helicopter models
A great store for RC helicopters and other RC models
HobbyTron - RC helicopters and all other hobby items - Through this banner you will find a lot of remote control hobby models for an affordable prize, among those many helicopters. You will also find other types of hobby items. The collection of electronic components is especially coprehensive.
DinoDirect - Store with good offers on
helicopter models, helicopter batteries and more
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interior home equipment, exterior equipment,
consumer electronics - and also many hobbby products -
This is a general wholesale and
lowprice store where you can find a lot of items of several categories,
especially electronics. Many of the items laid out here are very advanced. You
can find a lot of helicopter models here, and models of the most advanced type
on the market, like turbine driven helicopter models.
Warehouses for rc aircrafts and more
- especially many items suited for children - In these two collections of hobby products you will find a lot of remote controle hobby
aircraft models for an
affordable prize. Most models are electric driven. You will also find all other types
of hobby items.
This link lead to TrenTime Toys
Product examples from the
presented stores
Example of advanced RC helicopters and
equipment from the
stores presented.
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Fixed-winged aircraft models
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More advanced helicopter models
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RC model boats -
More RC model boats -
Back to main menu of all hobby and professional products
INFORMATION ABOUT VEHICLES
TECHNOLOGY - Especially RC vehicles
- The working principles of
an aerplane
- Motor
technologies for RC aircrafts and vehicles
- About remote controle transmitters and resceivers
- Battery technology for RC
vehicle
models - please see below
ABOUT RADIO CONTROLLED (RC)
HELICOPTER TECHNOLOGY New
developments in battery and electric motor techology has made it possible to
construct model helicopters driven by electricity from batteries and of many
sizes. There are small models you can fly inside your opwn house and greater
robust models for outdoor flight with a great action radius. A
helicopter must have several mechanisms to controle the flight. The speed of the
rotor must be controlled, or alternatively the attach angle of the blades can be
controlled instead, in order to controle the power of flight. The tilt angle
foreward-backards and right-left of the main rotor must be controlled. And the
speed of the tail rotor or alternatively the attack angles of the tail rotor
blades must be regulated to controle rotation of the fuselage. These
controles must be directed through the radio units by the pilot and inside the
helicopter, and by microprocessors inside the helicopter. The different models
have different numbers of controle possiblilities and hence controle channels in
the radio controle unit. Advanced helicopter models have many, but are also then
more demanding to operate and require more skill from the pilot. Cheaper
helicopter models have fewer control grades and therefore fewer contole channels,
but they are easier to operate. In many advanced helicopter models several
controle grades are also taken care of automatically by the electronics, and
therefore require easier stearing controle operations. Most of the helicopters
at this page are advanced models with many controle possibilities.
Advanced models with 6 or 7 control grades and the equal amount of channels have
the ability to perform acrobatic maneuvers. These are useually called aerobatic
helicopter models. Many
of the advanced models can in great extend be customized for the choise of tyhe
owner. You can for many models buy different canopies to make the helicopter
look as you wish yourself. You can also install special equipment as for example
surveillance cameras in many models.
RC helicopter designs A
helicopter must have one or more rotors that give lift and that can be tilted in
various direction to make movement in the wanted direction.
These roteors make a screwing force that tries to turn the helicopter around.
This torque must be cotrolled so that it is upweighted or just turn the
helicopter when this is wanted.
There are many designs that achieve these objective. Most of the designs are
also used in real-world work helicopters, but model builders have a greater
opportunity to use their fantacy to make fancy constructions.
One is to have a single rotor for lift and movement and a vertical tail rotor
that controles the torque. Tis is also the most usual design of real-world
helicopters. By varying the force of the tail rotor, the toque can be
counteracted wholly or partly, or one can make a torque in the opposite
direction.
Another way is to use two main rotors over each other that retate in the
opposite direction. By letting the rotors rotate at exaclky the same speed, or
by letting them rotate by a somewhat different velocity, the torque can be
ounteracted, or one can make a wanted torque in a direction so that the
helicopte turns.
Still another way is to have two main rotors after each other, one in the front
and one at the tail end that rotate in the opposte direction, so that they
counteract the torque of each other. By tilting the rotors differently, one can
get the helicopter to turn in a direction wanted.
The engines used are typically methanol-powered two-stroke motors, but gasoline,
jet turbine and increasingly electric brushless motors combined with a
high-performance lithium ion polymer battery are also used.
There are also possible to make fantacy models of various kinds, for example
with many small rotors distributed aound the frame of the vehicle.
RC helicopter motors
Traditionally model helicopters have been made with small two-stroke piston
engines. However, by now electric motors driven by rechargeable batteries are
steadily more used and are by now the most sold.
For powerful models combustion engines are still used. One can find model
helicopters with two-stroke nitro-driven engines , but even turbine-engine
driven model helicopters are to be found. In
former days model airplanes often used two-stroke glow-plug-motors driven by
methanole. This kind of motor technology is not widely used anymore.
How the mechanical parts produce
flight
Exactly how the parts work singly and together to produce flight varies greatly
for model helicopters. For advenced model helicopters they work just as in real
helicopters or in an even more advanced way. For simple helicopters, the working
principles are very simple.
However, advanced technical mechicalsolutions are in many models combined
with simple controlling actions, so that the helicopter is simple to use also
for a beginner.
The power and thus the speed of lift and flight can be controlled in two ways:
In simple models it is controlled by the rotational speed of the rotor. In
advanced models it is controlled by the attcak angle of the rotor blades, as in
a real helicopter. This is called collective pitch. By
this mode of acction the rotor blades are first accelerated up to the working
speed. Then the helicopter blades are turned to controle the power for lifting
and horisontal motion. To
achieve this power controle that the rotor does, the power of the motor must be
set correctly at any time. It
most be controlled whether the helicopter is going upwards, downwards, forewards,
sidewise or backwards. This is done by tilting the rotor in the desired
direction.
The torque produced by the rotor tend to rotate the fuselage in the opposite
direction of the rotor rotation. This rotation can be of opposed by the
controlling the power of the tail rotor. But many model helicopters have other
means of doing it, such as two contrarotating rotors over each other.
The fuselage must be swung to head in the right direction, usually the direction
of the flight. This is also done by the power of the tail rotor. The torque from
the
How
a RC helicopter is controlled
There are several kinds of contol mechanism that can be applied in a RC
helicopter to produce the right flight actions.
Not any RC helicopter have all the controls possible, and often two or more
mechanical flight controle actions are linked and controlled together by
the controlling electronics and the controle actions of the pilot are thereby
made more easy.
RC helicopters having many controls are more
demanding to fly, but allows much more modes of flight and maneuvering types
than helicopters with fewer controls. -
The throttle or power of the engine must be controlled. -
The rotating speed of the main rotor may be controlled. If the angle of the
rotor blades are held constant, the rotating speed will determine the lifting
and flight power, and this speed and power is controlled by the throttle. -
In simple RC helicopters the throttle is varied, this varies the speed of the
main rotor and hence also he lifting and movement power. -
In more advanced helicopters the main rotor blades may be turned to variate their angle (collective pitch).
The
power of lift and movement can then be controlled by varing this angle. At
start the speed of the main rotor is accelerated to the working speed.
Thereafter the speed of the main rotor is held constant by controlling the throttle. This is actually the main way of varying the power in an advanced helicopter. -
In some advanced helicopters, the rotating speed of the main rotor is automatically
controlled, and the throttle is controled together with the tilting angle of the
main rotor blades. -
Tilting of the top rotor to left or right (roll) can be controlled. -
Tilting of the top rotor foreward or backward (pitch) can be controlled. -
The rotating speed of the tail rotor may be controlled. In this way the
helicopter can be turned. -
The angle of the tail rotor blades may be controlled. If the rotating
speed of the tail rotor is hold constant, the power of he tail rotor, and hence
the power to turn the helicopter can be varied by controlling this angle.
Four controls is a very usual configuration: Aileron (Roll - Cyclic Pitch),
Elevator (Fore-Aft Cyclic Pitch), Rudder (Yaw) and Pitch/Throttle (Collective
Pitch/Power).
Nitro helicopters come in different sizes: 15, 30, 50, 60 and 90 size. These
numbers originated from the size of nitro engine used in the different models
(0.30 cu in, 0.50 cu in and so on). The bigger and more powerful the engine, the
larger the main rotor blade that it can turn and hence the bigger the aircraft
overall.
Electric RC helicopters
The smallest radio-controlled helicopter made (Guinness World Records 2006) is
the Picoo Z sold at many toy stores, electronics stores and internet stores,
costing about $40/£30. The next smallest is the Micron FP helicopter, which is
also a battery-operated R/C helicopter.
Radio transmitters and resceiver
for remote controle helicopters
Brands: Spektrum, Futaba, JR, Hitec, Airtronics, Sanwa, Multiplex
Radios emit the FM signal in two types of modulation.
Construction
Construction is typically of plastic, glass-reinforced plastic, aluminium or
carbon fibre. Rotor blades are typically made of wood, fibreglass or carbon
fibre. Models are typically purchased in kit form from one of about a dozen
popular manufacturers and take 5 to 20 hours to completely assemble.
How to individualize RC
helicopters Some
helicopters are sold as scale models of real life helicopters. Others are
however sold with only a minimal fusledge canopy. They can of course be used as
is, but you can shift out the dummy canopy with some canopy made to resamble the
fuslage of some real life or historical helicopter.
Advanced Rc helicopters can also be furnished with spy or surveillance cameras,
so that you also can use the helicopter as a surveillance tool. It is
also possible to buy helicopter scheletons without motor, but with rotors and
all controlling mechanics. Then one can buy motos, vanopy and radiocontrolling
units afte one's own whish and this way indibidualize the helicopter.
Helicopters with single rotors based
on the same technology as real life helicopters
The various helicopter controls are effected by means of small servo motors. A
piezoelectric gyroscope is typically used on the tail rotor (yaw) control to
counter wind- and torque-reaction-induced tail movement. This "gyro" does not
apply a mechanical force, but rather, electronically adjusts the control signal
to the tail rotor servo.
The controls must have signals from the pilot. This is achieved by a tranmittor
held by the pilot and a resceiver installed in the helicopter. The transmittor t
have as many channels as there are mechanical controls in the helicopter. The
number of controls and hence the channels vary between 2 and 6, where the most
advanced, but also the must difficult to fly helicopters have 6 channels.
For a non-3D helicopter, the Pitch will range from about -1 degree at 0%
throttle to about 11 degrees at 100% throttle.
Nitro RC helicopters
Recent advancements in battery technology make electric flying more feasible in
terms of flying time. However, these lithium polymer batteries can explode upon
overheating. U.S. Consumer Product Safety Commission Recall Alert.
In the past electric helicopters were used mainly indoors due to the small size
and lack of fumes. Larger electric helicopters suitable for outdoor flight and
advanced aerobatics have become a reality over the last few years and have
become very popular. Their quietness has made them very popular for flying sites
close to residential areas and in places such as Germany where there are strict
noise restrictions. Nitro helicopters have also been converted to electric power
by commercial and home made kits.
Small fixed-pitch helicopters need a 4-channel radio (throttle, elevator,
aileron, rudder) while collective-pitch models need a minimum of 5 channels with
6 being most common (throttle, collective pitch, elevator, aileron, rudder and
gyro gain). Because of the normal interaction of the various control mechanisms,
advanced radios include adjustable mixing functions, such as throttle/collective
and throttle/rudder.
Radio prices vary from $199-$3,000 USD.
Modulation
PPM is cheaper than PCM and is generally used in low-end helicopters. The lack
of a failsafe in PPM makes it more suited to small, less dangerous models.
Higher-end radios offer PCM and PPM modulation for better compatibility with all
radio receivers.
PCM - Pulse Code Modulation: A scheme in which the commanded position for each
servo is transmitted as an encoded number. Manufacturers use their own
proprietary system to encode this number with various bits of precision. JR use
Z-PCM (10 bits, 512 values) then S-PCM (11 bits, 1024 values). Futaba use
PCM-1024 and G3 PCM (12 bits, 2048 values). PCM also includes a feature called
Fail Safe to set servo positions to a predefined position, or to hold them at
the last valid position, should a valid radio signal be lost.
PPM - Pulse-position modulation: A scheme in which the commanded position for
each servo is transmitted as the duty-cycle of the transmitted pulses 1 per
servo position.
These model helicopters contain many moving parts, from the swashplate to the
mechanical linkages that allow the rotor to be tilted thus controlling direction.
The construction of helicopters has to be more precise than for fixed-wing model
aircraft, because helicopters are susceptible to even the smallest of vibrations,
which can cause problems when the helicopter is at flight.