INDEX

1. R/C Helicopter( abstract)

2. Introduction

3. Primary helicopter control

4. Circuit Diagram

5. Component’s Description

6. P.C.B. Manufacturing Process

7. BOARD TYPES

8. Chronology

9. PCB Layout

10. Theory

11. control

12. Coaxial RC helicopters

13. Military Services

14. Air Ambulance

15. Reference

R/C Helicopter

ABSTRACTRemote sensing is just what the expression implies: looking at an object from the distance. Normally this is subconsciously associated with air- or spacecraft in the classical sense. Unmanned aerial vehicles also known as drones used for reconnaissance purposes were limited to the military due to financial and logistical reasons. Recent developments however have given rise to sophisticated remote controlled aerial vehicles known as quad-copters that are able to carry sensors which have grown smaller and cheaper over the years. Drones that used to be considered a privilege of the military have gone mainstream and are now accessible to everybody with an abundance of applications waiting to be implemented.” The earth will don an electronic skin” The world with its varied systems is complex. The world has accumulations of inhabitants and valuable infrastructure in places at risk. The world is continuously changing. Therefore not only decision makers need reliable information fast, which, as it happens, almost always has a spatial context. In 1999 there was an article in Business Week titled “The earth will don an electronic skin”1 whose author postulated that within 10 years there would be trillions of sensors equipped with a microprocessor and radio, monitoring everything from the environment, our cities and highways to the functions of our body and transmitting this information to the internet in real-time. Remote sensing plays a vital role in this information gathering as do terrestrial sensors that can corroborate the data ascertained by the remote sensors.

TECHNICAL DATA & FEATURESRange: approximately 500 meters due to the capacity of the remote control and video downlink. Weight (empty): 720 g Payload: Up to 600 g. The drone will carry 900 g which however reduces the flight time to 7min. Flight duration: 10-30 minutes, depending on the payload Dimensions: Over-all (propeller tips): 82 cm, motor-axis to motor-axis 52 cm Ground clearance: 15 cm Waypoint navigation: It is possible to uploada file with waypoints which the drone will autonomously fly to. Action to be performed at each waypoint, i.e. take a picture in a particular direction can be programmed. GPS-come-home: The drone will autonomously go back to its initial starting position provided this position was memorized at take-off. GPS-hold: The drone will hold its position according to its GPS-fix without the pilot having to intervene. This makes operating the drone very easy since one can concentrate on other tasks too.SensorGIS – real-time geodata Having almost arrived at the designated point in time of the 1999 article, at least from the authors’ perspective the part of

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the environmental monitoring seems to have come true. There are wireless sensor networks (WSN) in operation that are made up of numerous so-called sensor nodes. These consist of a microprocessor, memory, radio, energy supply and sensors. Switched on they will autonomously connect to their neighbouring sensor-nodes and transmit data in a multi hop fashion to the so-called gateway from where the data is then sent via the mobile radio network to databases residing on the internet. Enhanced with a coordinate the mere values are turned into geo-data which can be displayed on a map and which are accessible to geographical information system (GIS) analysis. The combination of WSN and standardized, webbased GIS (WebGIS) is called SensorGIS2 which delivers geo-data in real-time. These SensorGIS-nodes however are earth-bound and WSN to date typicallycover a few square kilometers at the most.Upgrading the information from thesenetworks in real-time with photos or other.sensory data from aeroplanes, helicopters or even satellites would be a costly venture fora comparatively small area if it were not forthe quad-copters that by now are availableat affordable prices.Range: approximately 500 meters due to the capacity of the remote control and video downlink. Weight (empty): 720 g Payload: Up to 600 g. The drone will carry 900 g which however reduces the flight time to 7min. Flight duration: 10-30 minutes, depending on the payload Dimensions: Over-all (propeller tips): 82 cm, motor-axis to motor-axis 52 cm Ground clearance: 15 cm Waypoint navigation: It is possible to upload a file with waypoints which the drone will autonomously fly to. Action to be performed at each waypoint, i.e. take a picture in a particular direction can be programmed. GPS-come-home: The drone will autonomously go back to its initial starting position provided this position was memorized at take-off. GPS-hold: The drone will hold its position according to its GPS-fix without the pilot having to intervene. This makes operating the drone very easy since one can concentrate on other tasks too.

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Introduction

There are a number of quad-copter projects3 powered by enthusiasts who enjoy tinkering with the technology and making it fly. There are in addition some companies4 providing this technology for ‘serious’ applications. One commercial product, which this article is based on, is called HighKopter which sticks out because the flight software is open source which enables the user to add his own features or improve on the ones that are already there.Quad-copters look like props from a science-fiction film but are in fact versatile little flight machines. On each end of two crossed rods are four brushless propellers which provide the lift and steering capabilities.Opposite propellers rotate in the same direction with one pair rotating clock- and the other pair rotating anti-clockwise to get rid of the torque. Typical quad-copters are powered by lithium-ion batteries,are very quiet and eco-friendly. They can be flown indoors as well as outdoors. With a lift-off weight of less than 5000 grams the drones are considered toys which can be operated without a license in Germany. German aviation law allows the operation to a maximum altitude of 150 meters although technically the drones can fly much higher. This however requires a regular flight permission from the nearest flight controller. The drone comes equipped with flight software, a GPS, barometric altitude control, a tilt-compensated compass and a videodownlink so that the person steering the drone actually sees what the drone ‘sees’ by way of its camera. The equipment is shipped in ruggedized cases so that it is ready for outdoor use. Aerial photos / Orthophotos As to quad-copter applications, one of the most obvious uses is to attach a video- or still-camera to the drone and take pictures. I will not list the possible areas of application, since there are plainly too many. It is easy to see that an altered perspective can have great benefitssince a lot of information can be gleaned from these types of pictures. One can take this process one step further by creating orthophotos from these aerial images. Using a digital terrain model one can rectify the distortions brought about by the perspective of the camera and the topography being photographed. The result is an image that at the same time has the qualities of a picture and that of a map: one can directly measure angles, distances and areas while looking at the land surface as it iswithout any map symbols. Digital terrain models The Department of Photogrammetry, University of Bonn, has used images from a video sequence filmed during the flight of the quad- copter to extract a digital terrain model (DTM). The results are impressive: With a horizontal resolution of 2-3 cm and a vertical resolution of approximately 7 cm the data

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is good for a variety of applications: • Volume calculations for landfills orstripmining renaturations• Planning noise-barriers in the context of the EU directive on environmental noise • Monitoring glaciers, volcanoes, land-slides Figure 6 shows the reconstructed surface from a video acquired by a quad-copter flying at an altitude of 30 meters using a 1 megapixel camera in the Siebengebirge near Bonn. A building in the upper left and a vineyard in the lower right corner of the image can be discerned. The achievable accuracy depends to a large extent on altitude, resolution and focal width of the camera. Other sensors Any number of other sensors can be made tofly provided they are not too heavy. Gas sensors that are able to detect air-quality could provide valuable information for rescue organizations. Infrared sensors that provide thermal images can be used to detect heat distributions on built infrastructure or the environment. Sensors detecting humidity and pressure can deliver meteorological information that would otherwise be difficult to obtain. Here too, the list would be endless and only limited by the imagination. Transport Besides actually fitting a sensor to a drone one can use it for transport purposes albeit with a limited capacity. Moving sensors to or from otherwise inaccessible locations is possible through the use of an external cargo hook. The same holds true for retrieving samples from water bodies, swamps and marshes. This too is just a small section of possible scenarios.Geodata & Interoperability Since the drone is equipped with a GPS all data that is transmitted to the ground can potentially be used as geodata. An aerial photograph for example can be georeferenced and incorporated into a WebGIS. This holds great potential for ‘patching’ existing data since data representing large areas is usually updated with a cycle spanning several years.Other sensory data like air-quality corresponding to a point is very easily displayed on a map. Provided the WebGIS conforms to standards of the Open Geospatial Consortium (OGC) data can be made available to others on-the-fly through the use of established protocols. Future prospects Basically a drone is a flying sensor platform that allows the acquisition of data in a three dimensional space and grants access to areas that are otherwise difficult to reach The technology to transmit this data in real-timeto appropriate information systems is available. Future work will concentrate on fusing drone technology with SensorGISapplications to gain that extra advantage forreal-time geodata acquisition.

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A look at primary RC helicopter controls

Learning the fundamentals of rc helicopter controls isn't as scary as it might seem, and understanding which function does what on a radio control helicopter will make life a lot easier for you in your early days as a model heli pilot.The primary method of making areal helicopter change direction while flying is through pitch control of the main rotor blades, either independently or collectively.However, in the rc world in recent years there has been a huge influx of electric rc helicopters that do not have complete independent pitch control - these are known asFixed Pitch (FP) rc helicopters.Emulating the real helicopters are the Collective Pitch (CP) models which, although harder to learn on, are more agile and smoother to fly.

FP or CP, what's the real difference?

To control an rc helicopter, the pitch angle of the rotor blades must be changed in relation to the air flowing over them; this change varies the amount of lift generated by the blades (pitch angle is referred to as 'Angle of Attack' when the blade is moving).

But in truth, the terms 'FP' and 'CP' are a little misleading because both terms only refer to the collective (ie altitude) control of the helicopter. The cyclic(directional) control method is basically the same for FP and CP helicopters.This cyclic control changes the pitch angle of the whole rotor disc, which is the imaginary circle in the air drawn by the tips of the spinning blades, and both FP and CP rc helicopters use a flybar to influence the angle of the rotor disc. This flybar is a short rod perpendicular to the main rotor blades. At each end

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of the flybar is an airfoil paddle, and the flybar moves in direct response to the tilting of the swash plate, controlled by the servos - one for sideways movement and the other for fore/aft movement.

Above, the rotor head assembly of a Fixed Pitch rc helicopter

As the flybar rotates in response to the tilting of the swash plate, so the Angle of Attack of the paddles changes. This effects the amount of lift being generated by them and so they rise and fall accordingly. The paddles always work against each other ie if one rises then the other falls, and vice versa. This in turn exaggerates the movement of the flybar, and the end result is that the whole rotor disc tilts in response to the changes in lift being experienced at the paddles. The helicopter becomes 'unbalanced' and so leans to the side that is experiencing lesser lift, thus changing direction.So, the primary difference between FP and CP helicopters is in the collectivecontrol, and this is influenced by the lift generated by the main blades acting together ie 'collectively'.In an FP model the main blades are fixed to the main rotor head and cannot be pivoted about their longitudinal axis. Altitude has to be controlled by thespeed of the blades (ie motor speed) - faster spinning blades generate more lift and vice versa. But in a CP model the main blades can be pivoted about their longitudinal

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axis in relation to the main rotor head, thus changing the pitch angle of them and the associated amounts of lift. The motor can therefore be kept at a more constant speed, and altitude is controlled by changing the pitch angle of the blades.

Above left, an FP rotor head compared to the more complex CP one, right

Collective pitch is essential for any form of aerobatic flying, especially inverted flight where negative blade pitch is a necessity.

RC helicopter control channels

For an rc helicopter to have proper control there needs to be at least 4 channels - left/right cyclic, fore/aft cyclic, left/right yaw and collective pitch and/or throttle. If these sound confusing, compare them to the 4 primary airplane controls and you'll see the relationship:

Helicopter control Airplane control Action

left/right cyclic Left/right aileron roll

fore/aft cyclic elevator/thrust* airspeed

left/right yaw Left/right rudder yaw

collective pitch/throttle

elevator/thrust* climb/dive

* airplane elevator and thrust are shown together becauseboth influence airspeed and climb/descentTaking a basic 4 channel FP rc helicopter as an example, there will be 2 servos controlling the cyclic pitch - one for left/right and the other for fore/aft. The 3rd channel will be main motor speed control and the 4th channel will be tail rotor motor speed (left/right yaw). This left/right yaw control is used in conjunction with, or against, the naturaltorque force that is generated by the spinning main rotors; as a

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natural reaction to the spinning blades, the fuselage of the helicopter will always want to spin rapidly in the opposite direction.

The tail rotor generates sideways thrust in the same way as a normal airplane propeller does. If the amount of thrust equals the level of torque, then the helicopter fuselage won't spin round. If the thrust exceeds the torque, the fuselage will yaw one way and if the torque exceeds the thrust then the fuselage will naturally yaw the other way.

The Gyro

The use of yaw control in rc helicopters is made easier by a gyro which is an electronic device that is connected between the receiver and the tail rotor control.  The gyro senses any rotational movement of the helicopter that isn't a result of a signal to the receiver, and it makes fine adjustments to the tail rotor speed or blade pitch to suit the torque force at that precise moment, hence dampening out any unwanted yaw. Gyros make these calculations and corrections at lightning speed, so much so that the pilot doesn't notice anything other than a stable helicopter!

The gyro sensitivity (gain) can be adjusted by the pilot, and normal stick movements at the transmitter send the receiver rudder signal through the gyro so that the helicopter can be turned onto the desired heading by the pilot.Heading Hold Gyros go one step further than a standard gyro by performing more complex calculations to keep the helicopter pointing in the direction that the pilot intended. A more definite input is required from the pilot to overcome an HHG, and the new change will be memorized by the gyro which will maintain this heading to a fairly accurate degree, until a further change is made.

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RC helicopter mixer boards/RXs

Most rc helicopters use micro-processor mixer boards to save space and weight. The electronic circuit board based unit is a device that typically combines the receiver, gyro and motor electronic speed control (ESC for electric helicopters). A further function can be CCPM, or Cyclic/Collective Pitch Mixing, but this is usually just found on the more advanced helis. The mixer board unit is about the same size and appearance as a standard rc receiver and weighs considerably less than using separate devices.

Circuit Diagram

TRANSMITTER

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RECIEVER

Component’s Description

RESISTORS: -

A Resistor is a heat-dissipating element and in the electronic circuits it

is mostly used for either controlling the current in the circuit or developing a

voltage drop across it, which could be utilized for many applications. There

are various types of resistors, which can be classified according to a number

of factors depending upon:

(I) Material used for fabrication

(II) Wattage and physical size

(III) Intended application

(IV) Ambient temperature rating

(V) Cost

Basically the resistor can be split in to the following four parts from

the construction viewpoint.

(1) Base

(2) Resistance element

(3) Terminals

(4) Protective means.

The following characteristics are inherent in all resistors and may be

controlled by design considerations and choice of material i.e. Temperature

co–efficient of resistance, Voltage co–efficient of resistance, high frequency

characteristics, power rating, tolerance & voltage rating of resistors.

Resistors may be classified as

(1)Fixed

(2)Semi variable

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(3)Variable resistor.

In our project carbon resistors are being used.

CAPACITORS

The fundamental relation for the capacitance between two flat plates

separated by a dielectric material is given by:-

C=0.08854KA/D

Where: -

C= capacitance in pf.

K= dielectric constant

A=Area per plate in square cm.

D=Distance between two plates in cm

Design of capacitor depends on the proper dielectric material with

particular type of application. The dielectric material used for capacitors

may be grouped in various classes like Mica, Glass, air, ceramic, paper,

Aluminum, electrolyte etc. The value of capacitance never remains constant.

It changes with temperature, frequency and aging. The capacitance value

marked on the capacitor strictly applies only at specified temperature and at

low frequencies.

LED (Light Emitting Diodes)

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As its name implies it is a diode, which emits light when forward

biased. Charge carrier recombination takes place when electrons from the N-

side cross the junction and recombine with the holes on the P side. Electrons

are in the higher conduction band on the N side whereas holes are in the

lower valence band on the P side. During recombination, some of the energy

is given up in the form of heat and light. In the case of semiconductor

materials like Gallium arsenide (GaAs), Gallium phoshide (Gap) and

Gallium arsenide phoshide (GaAsP) a greater percentage of energy is

released during recombination and is given out in the form of light. LED

emits no light when junction is reverse biased.

TRANSISTOR:-

A transistor consists of two junctions formed by sandwiching either p-

type or n-type semiconductor between a pair of opposite types. Accordingly,

there are two types of transistors namely: -

(1) n-p-n transistor (2) p-n-p transistor

(NPN) (PNP)

An n-p-n transistor is composed of two n-type semiconductors separated by

a thin section of p type. However a p-n-p transistor is formed by two p

sections separated by a thin section of n-type.

In each type of transistor the following points may be noted.

1. There are two p-n junctions, therefore a transistor may be regarded as

combination of two diodes connected back to back.

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2. There are three terminals taken from each type of semiconductor.

3. The middle section is a very thin layer, which is the most important

factor in the functioning of a transistor.

4. Transistor can be used as an Amplifier also.

A transistor raises the strength of a weak signal and thus acts as an

amplifier. The weak signal is applied between emitter base junction and

output is taken across the load Rc connected in the collector circuit (in

common emitter configuration). In order to achieve faithful amplification,

the input circuit should always remain forward biased. To do so, a dc voltage

is applied in the input in addition to the signal. This dc Voltage is known as

biasing voltage and its magnitude and polarity should be such that it always

keeps the input circuit forward biased regardless of the polarity to the signal

to be amplified.

As the input circuit has low resistance a small change in signal voltage

causes an appreciable change in emitter current. This causes change in

collector current (by a factor called current gain of transistor) due to

transistor action. The collector current flowing through a high load

resistance Rc produces a large voltage across it. Thus a weak signal applied

to the input circuit appears in the amplified form in the collector circuit. This

is how a transistor acts as an amplifier.

Transistor may be used in different configuration like CB (common base) &

CC (common collector) according to requirements of amplifier (impedance

matching, buffer amplifier etc.).

TRANSFORMER

Definition: -

The transformer is a static electro-magnetic device that transforms one

alternating voltage (current) into another voltage (current). However, power

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remains the some during the transformation. Transformers play a major role

in the transmission and distribution of ac power.

Principle: -

Transformer works on the principle of mutual induction. A transformer

consists of laminated magnetic core forming the magnetic frame. Primary

and secondary coils are wound upon the two cores of the magnetic frame,

linked by the common magnetic flux. When an alternating voltage is applied

across the primary coil, a current flows in the primary coil producing

magnetic flux in the transformer core. This flux induces voltage in

secondary coil.

Transformers are classified as: -

(a) Based on position of the windings with respect to core i.e.

(1) Core type transformer

(2) Shell type transformer

(b) Transformation ratio:

(1) Step up transformer

(2) Step down transformer

(a) Core & shell types: Transformer is simplest electrical machine, which

consists of windings on the laminated magnetic core. There are two

possibilities of putting up the windings on the core

(1) Winding encircle the core in the case of core type transformer

(2) Cores encircle the windings on shell type transformer.

(b) Step up and Step down: In these Voltage transformation takes place

according to whether the

Primary is high voltage coil or a low voltage coil.

(1) Lower to higher-> Step up

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(2) Higher to lower-> Step down

DIODES

- +

It is a two terminal device consisting of a P-N junction formed either

of Ge or Si crystal. The P and N type regions are referred to as anode and

cathode respectively. Commercially available diodes usually have some

means to indicate which lead is P and which lead is N.

RELAY

In this circuit a 12V magnetic relay is used. In magnetic relay, insulated

copper wire coil is used to magnetize and attract the plunger .The plunger is

normally connected to N/C terminal. A spring is connected to attract the

plunger upper side. When output is received by relay, the plunger is attracted

and the bulb glows.

P.C.B. Manufacturing Process

It is an important process in the fabrication of electronic equipment. The

design of PCBs (Printed Circuit Boards) depends on circuit requirements

like noise immunity, working frequency and voltage levels etc. High power

PCBs require a special design strategy.

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The fabrication process to the printed circuit board will determine to a

large extent the price and reliability of the equipment. A common target

aimed is the fabrication of small series of highly reliable professional quality

PCBs with low investment. The target becomes especially important for

customer tailored equipments in the area of industrial electronics.

The layout of a PCB has to incorporate all the information of the board

before one can go on the artwork preparation. This means that a concept

which clearly defines all the details of the circuit and partly defines the final

equipment, is prerequisite before the actual lay out can start. The detailed

circuit diagram is very important for the layout designer but he must also be

familiar with the design concept and with the philosophy behind the

equipment.

BOARD TYPES

The two most popular PCB types are:

1. Single Sided Boards

The single sided PCBs are mostly used in entertainment electronics

where manufacturing costs have to be kept at a minimum. However in

industrial electronics cost factors cannot be neglected and single sided

boards should be used wherever a particular circuit can be

accommodated on such boards.

2. Double Sided Boards

Double-sided PCBs can be made with or without plated through holes.

The production of boards with plated through holes is fairly

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expensive. Therefore plated through hole boards are only chosen

where the circuit complexities and density of components does not

leave any other choice.

Chronology

The following steps have been followed in carrying out the project.

1. Study the books on the relevant topic.

2. Understand the working of the circuit.

3. Prepare the circuit diagram.

4. Prepare the list of components along with their specification. Estimate

the cost and procure them after carrying out market survey.

5. Plan and prepare PCB for mounting all the components.

6. Fix the components on the PCB and solder them.

7. Test the circuit for the desired performance.

8. Trace and rectify faults if any.

9. Give good finish to the unit.

10. Prepare the project report.

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DESIGN SPECIFICATION

(I) STEPS TAKEN WHILE PREPARING CIRCUIT

(A) PCB DESIGNING

The main purpose of printed circuit is in the routing of electric currents

and signal through a thin copper layer that is bounded firmly to an insulating

base material sometimes called the substrate. This base is manufactured with

an integrally bounded layers of thin copper foil which has to be partly etched

or removed to arrive at a pre-designed pattern to suit the circuit connections

or other applications as required.

The term printed circuit board is derived from the original method

where a printed pattern is used as the mask over wanted areas of copper. The

PCB provides an ideal baseboard upon which to assemble and hold firmly

most of the small components.

From the constructor’s point of view, the main attraction of using

PCB is its role as the mechanical support for small components. There is less

need for complicated and time consuming metal work of chassis

contraception except perhaps in providing the final enclosure. Most straight

forward circuit designs can be easily converted in to printed wiring layer the

thought required to carry out the inversion cab footed high light an possible

error that would otherwise be missed in conventional point to point

wiring .The finished project is usually neater and truly a work of art.

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Actual size PCB layout for the circuit shown is drawn on the copper

board. The board is then immersed in FeCl3 solution for 12 hours. In this

process only the exposed copper portion is etched out by the solution.

Now the petrol washes out the paint and the copper layout on PCB is

rubbed with a smooth sand paper slowly and lightly such that only the oxide

layers over the Cu are removed. Now the holes are drilled at the respective

places according to component layout as shown in figure.

(B) LAYOUT DESIGN:

When designing the layout one should observe the minimum size

(component body length and weight). Before starting to design the layout we

need all the required components in hand so that an accurate assessment of

space can be made. Other space considerations might also be included from

case to case of mounted components over the printed circuit board or to

access path of present components.

It might be necessary to turn some components around to a different

angular position so that terminals are closer to the connections of the

components. The scale can be checked by positioning the components on the

squared paper. If any connection crosses, then one can reroute to avoid such

condition.

All common or earth lines should ideally be connected to a common

line routed around the perimeter of the layout. This will act as the ground

plane. If possible try to route the outer supply line to the ground plane. If

possible try to route the other supply lines around the opposite edge of the

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layout through the center. The first set is tearing the circuit to eliminate the

crossover without altering the circuit detail in any way.

Plan the layout looking at the topside to this board. First this should be

translated inversely, later for the etching pattern large areas are

recommended to maintain good copper adhesion. It is important to bear in

mind always that copper track width must be according to the recommended

minimum dimensions and allowance must be made for increased width

where termination holes are needed. From this aspect, it can become little

tricky to negotiate the route to connect small transistors.

There are basically two ways of copper interconnection patterns under

side the board. The first is the removal of only the amount of copper

necessary to isolate the junctions of the components to oneanother. The

second is to make the interconnection pattern looking more like

conventional point wiring by routing uniform width of copper from

component to component.

(C) ETCHING PROCESS:

Etching process requires the use of chemicals. acid resistant dishes

and running water supply. Ferric chloride is mostly used solution but other

etching materials such as ammonium per sulphate can be used. Nitric acid

can be used but in general it is not used due to poisonous fumes.

The pattern prepared is glued to the copper surface of the board using

a latex type of adhesive that can be cubed after use. The pattern is laid firmly

on the copper using a very sharp knife to cut round the pattern carefully to

remove the paper corresponding to the required copper pattern areas. Then

apply the resistant solution, which can be a kind of ink solution for the

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purpose of maintaining smooth clean outlines as far as possible. While the

board is drying, test all the components.

Before going to next stage, check the whole pattern and cross check

with the circuit diagram. Check for any free metal on the copper. The

etching bath should be in a glass or enamel disc. If using crystal of ferric-

chloride these should be thoroughly dissolved in water to the proportion

suggested. There should be 0.5 lt. of water for 125 gm of crystal.

To prevent particles of copper hindering further etching, agitate the

solutions carefully by gently twisting or rocking the tray.

The board should not be left in the bath a moment longer than is

needed to remove just the right amount of copper. Inspite of there being a

resistive coating there is no protection against etching away through exposed

copper edges. This leads to over etching. Have running water ready so that

etched board can be removed properly and rinsed. This will halt etching

immediately.

Drilling is one of those operations that calls for great care. For most

purposes a 0.5mm drill is used. Drill all holes with this size first those that

need to be larger can be easily drilled again with the appropriate larger size.

(D) COMPONENT ASSEMBLY: -

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From the greatest variety of electronic components available, which

runs into thousands of different types it is often a perplexing task to know

which is right for a given job.

There could be damage such as hairline crack on PCB. If there are, then they can be repaired by soldering a short link of bare copper wire over the affected part.

The most popular method of holding all the items is to bring the wires

far apart after they have been inserted in the appropriate holes. This will

hold the component in position ready for soldering.

Some components will be considerably larger .So it is best to start mounting

the smallest first and progressing through to the largest. Before starting, be

certain that no further drilling is likely to be necessary because access may

be impossible later.

Next will probably be the resistor, small signal diodes or other similar

size components. Some capacitors are also very small but it would be best to

fit these afterwards. When fitting each group of components mark off each

one on the circuit as it is fitted so that if we have to leave the job we know

where to recommence.

Although transistors and integrated circuits are small items there are

good reasons for leaving the soldering of these until the last step. The main

point is that these components are very sensitive to heat and if subjected to

prolonged application of the soldering iron, they could be internally

damaged.

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All the components before mounting are rubbed with sand paper so

that oxide layer is removed from the tips. Now they are mounted according

to the component layout.

(E) SOLDERING: -

This is the operation of joining the components with PCB after this

operation the circuit will be ready to use to avoid any damage or fault during

this operation following care must be taken.

1.A longer duration contact between soldering iron bit & components lead

can exceed the temperature rating of device & cause partial or total damage

of the device. Hence before soldering we must carefully read the maximum

soldering temperature & soldering time for device.

2.The wattage of soldering iron should be selected as minimum as

permissible for that soldering place.

3.To protect the devices by leakage current of iron its bit should be earthed

properly.

4.We should select the soldering wire with proper ratio of Pb & Tn to

provide the suitable melting temperature.

5.Proper amount of good quality flux must be applied on the soldering point

to avoid dry soldering.

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PCB Layout

TRANSMITTER

RECEIVER

Radio-controlled helicopters (also RC helicopters) are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training. Several basic designs of RC helicopters exist, of which some (such as those with collective pitch, meaning blades which rotate on their longitudinal axis to vary or reverse lift) are more maneuverable than others. The more maneuverable designs are often harder to fly, but benefit from greater aerobatic capabilities.

Flight controls allow pilots to control the collective and throttle (usually linked together), the cyclic controls (pitch and roll), and the tail rotor (yaw). Controlling these in unison enables the helicopter to perform most of the same manoeuvres as full-sized helicopters, such as hovering and backwards flight, and many that full-sized helicopters cannot.

The various helicopter controls are effected by means of small servo motors, commonly known as servos. 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 itself apply a mechanical force, but electronically adjusts the control signal to the tail rotor servo.

The engines typically used to be methanol-powered two-stroke motors, but electric brushless motors combined with a high-performance lithium polymer battery are now more common, as improved performance and decreasing prices bring these within reach of more people. Gasoline and jet turbine engines are also used.

Types of R/C helicopters

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Common power sources are Nitro (nitromethane-methanol internal combustion), electric batteries, gas turbines, petrol and gasoline.

Mechanical layouts include CCPM in all power sources, fixed-pitch electric rotors and coaxial electric rotors.

Practical electric helicopters are a recent development but have rapidly developed and become more common, overtaken nitro helicopters in common use. Gas-turbine helicopters are also increasing in popularity, although the high cost puts them out of reach of most people.

Nitro (Glow fuel)

Nitro or Glow fuel helicopters come in different sizes: 15, 30, 50, 60 and 90 size. These numbers originated from the size of 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. Typical flight times for nitro helicopters is 7-14 minutes depending on the engine size and tuning.

Electric

The 233 km/h fast electric helicopter TDR

Recent advancements in battery technology are making electric flying more feasible in terms of flying time. Lithium Polymer (LiPo) batteries are able to provide the high current required for high performance aerobatics while still remaining very light. Typical flight times are 4-12 minutes depending on the flying style and battery capacity.

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.

The smallest remote-controlled production model helicopter made (Guinness World Records 2006) is the Picooz Extreme MX-1 sold at many toy stores (although this is infrared controlled, not radio), electronics stores and

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internet stores, costing about $30 (£28). The next smallest is thestandard Picooz helicopter.

Recent advancements in battery technology are making electric flying more feasible in terms of flying time. Lithium Polymer (LiPo) batteries are able to provide the high current required for high performance aerobatics while still remaining very light. Typical flight times are 4-12 minutes depending on the flying style and battery capacity.

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.

The smallest remote-controlled production model helicopter made (Guinness World Records 2006) is the Picooz Extreme MX-1 sold at many toy stores (although this is infrared controlled, not radio), electronics stores and internet stores,. The next smallest is thestandard Picooz helicopter.

Several models are in contention for the title of the smallest non-production remote-controlled helicopter, including the Pixelito family of micro helicopters, the Proxflyer family, and the Micro flying robot.

RADIO GEARof the transmitted pulses 1 per servo position

Small fixed-pitch helicopters need a 4-channel radio (throttle, elevator, aileron, rudder), although micro helicopters that utilize a 2-channel infrared control system also exist; 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.

Well-known manufacturers of helicopter-specific radio controllers include: JR, Spektrum, Futaba, Hitec, Sanwa (known as "Airtronics" in North America), Multiplex (a division of Hitec)

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Modulation

Radios emit the FM signal in two types of 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 a digitally encoded number. Manufacturers use their own proprietary system to encode this number with various levels of precision (i.e. variable number of bits per servo position). JR use Z-PCM (9 bits, 512 different values: 0...511) then S-PCM (10 bits, 1024 values: 0...1023). Futaba use PCM-1024 and G3 PCM (11 bits, 2048 values: 0...2047). With PCM not all positions are broadcasted at one time (each frame) to save time. The odd numbered positions are sent as absolute in one frame, with the even sent only as differences from their previous values. The next frame the opposite is done. PCM includes a checksum at the end of the frame to check the signal's validity. Hence, if there is interference and the signal arrives distorted at the Receiver, utilizing the checksum it is able to know if it is the original. In case it is not, a feature called Fail-Safe is implemented to set servo positions to a predefined position, or to hold them at the last valid position.

PPM

Pulse-position modulation. A scheme in which the commanded position for each servo is transmitted .

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How helicopters fly and are controlled

Helicopters truly are amazing aircraft, and how helicopters fly is what makes them such versatile machines, being perfectly suited to roles ranging from military use to fire fighting and search and rescue.Helicopters have been around for centuries - well, the principle anyway - but it was Russian aircraft pioneer Igor Sikorsky who designed, built and in 1939 flew the first fully controllable single rotor / tail rotor helicopter - the fundamental concept that would shape all future helicopters.

Why helicopters are so versatile

A normal airplane can fly forward, up, down, left and right. A helicopter can do all this plus has the ability to fly backwards, rotate 360 degrees on the spot and hover ie stay airborne with no directional movement at all.

Helicopters may be limited in their speed, but the incredible maneuverability mentioned above is what makes them so useful in so many situations.

Above, the directions a helicopter can move in and the associated name of control

Controlling a helicopter

Helicopters require a completely different method of control than airplanes and are much harder to master. Flying a helicopter requires constant concentration by the pilot, and a near-continuous flow of control corrections. A conventional helicopter has its main rotor above the fuselage which consists of 2 or more rotor blades extending out from a central rotor head, or hub, assembly.The primary component is the swash plate, located at the base of the rotor head. This swash plate consists of one non-revolving disc and one revolving disc mounted directly on top. The swash plate is connected to the cockpit

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control sticks and can be made to tilt in any direction, according to the cyclic stick movement made by the pilot, or moved up and down according to the collective lever movement.But first, to explain how the main rotor blades are moved by the pilot to control the movement of the helicopter, we need to understand pitch...

The basics of pitch

Each rotor blade has an airfoil profile similar to that of an airplane wing, and as the blades rotate through the air they generate lift in exactly the same way as an airplane wing does [read about that here]. The amount of lift generated is determined by the pitch angle (and speed) of each rotor blade as it moves through the air. Pitch angle is known as the Angle of Attack when the rotors are in motion, as shown below: This pitch angle of the blades is controlled in two ways - collective andcyclic....

Collective control

The collective control is made by moving a lever that rises up from the cockpit floor to the left of the pilot's seat, which in turn raises or lowers the swash plate on the main rotor shaft, without tilting it. This lever only moves up and down and corresponds directly to the desired movement of the helicopter; lifting the lever will result in the helicopter rising while lowering it will cause the helicopter to sink. At the end of the collective lever is the throttle control, explained further down the page.As the swash plate rises or falls, so it changes the pitch of all rotor blades at the same time and to the same degree. Because all blades are changing pitch together, or 'collectively', the change in lift remains constant throughout every full rotation of the blades. Therefore, there is no tendency for the helicopter to move in any direction other than straight up or down.The illustrations below show the effect of raising the collective control on the swash plate and rotor blades. The connecting rods run from the swash plate to the leading edge of the rotor blades; as the plate rises or falls, so all blades are tilted exactly the same way and amount. Of course, real rotor head systems are far more complicated than this picture shows, but the basics are the same.

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Cyclic control

The cyclic control is made by moving the control stick that rises up from the cockpit floor between the pilot's knees, and can be moved in all directions other than up and down.

Like the collective control, these cyclic stick movements correspond to the directional movement of the helicopter; moving the cyclic stick forward makes the helicopter fly forwards while bringing the stick back slows the helicopter and even makes it fly backwards. Moving the stick to the left or right makes the helicopter roll and turn in these directions.The cyclic control works by tilting the swash plate and increasing the pitch angle of a rotor blade at a given point in the rotation, while decreasing the angle when the blade has spun through 180 degrees. As the pitch angle changes, so the lift generated by each blade changes and as a result the helicopter becomes 'unbalanced' and so tips towards whichever side is experiencing the lesser amount of lift.The illustrations below show the effect of cyclic control on the swash plate and rotor blades. As the swash plate is tilted, the opposing rods move in opposite directions. The position of the rods - and hence the pitch of the individual blades - is different at any given point of rotation, thus generating different amounts of lift around the rotor disc. To understand cyclic control another way is to picture the rotor disc, which is the imaginary circle above the helicopter created by the spinning blades, and to imagine a plate sat flat on top of the cyclic stick. As the stick is leaned over in any direction, so the angle of the plate changes very slightly. This change of angle corresponds directly to what is happening to the rotor disc at the same time ie the side of the plate that is higher represents the side of the rotor disc generating more lift.

Above, the layout of helicopter controls in relation to the pilot's seat

Rotational (yaw) control

At the very rear of the helicopter's tail boom is thetail rotor - a vertically mounted blade very similar to a conventional airplane propeller. This tail rotor is used to control the yaw, or rotation, of the helicopter (iewhich way the nose is pointing) and to explain this we first need to understand torque.Torque is a natural force that causes rotational movement, and in a helicopter it is caused by the spinning main rotor blades; when the blades are spinning then the natural reaction to that is for the fuselage of the helicopter

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to start spinning in theopposite direction to the rotors. If this torque isn't controlled, the helicopter would just spin round hopelessly!

So to beat the reaction of the torque, the tail rotor is used and is connected by rods and gears to the main rotor so that it turns whenever the main rotor is spinning.As the tail rotor spins it generates thrust in exactly the same way as an airplane propeller does. This sideways thrust prevents the helicopter fuselage from trying to spin against the main rotor, and the pitch angle of the tail rotor blades can be changed by the pilot to control the amount of thrust produced. Increasing the pitch angle of the tail rotor blades will increase the thrust, which in turn will push the helicopter round in the same direction as the main rotor blades. Decreasing the pitch angle decreases the amount of thrust and so the natural torque takes over, letting the helicopter rotate in the opposite direction to the main rotors. The pilot controls the pitch angle of the tail rotor blades by two pedals at his feet, in exactly the same way as the rudder movement is controlled in an airplane. NOTAR is an alternative method of yaw control on some helicopters - instead of a tail rotor to generate thrust, compressed air is blown out of the tail boom through moveable slots. These slots are controlled by the pilot's pedals in the same way as a tail rotor is. To generate more thrust, the slots are opened to let out more air, and vice versa.

NOTAR helicopters respond to yaw control in exactly the same way as tail rotor models and have a big safety advantage - tail rotors can be very hazardous while operating on or close to the ground and in flight a failing tail rotor will almost always result in a crash.

Throttle control

The throttle control is a 'twist-grip' on the end of the collective lever and is linked directly to the movement of the lever so that engine RPM is always correct at any given collective setting. Because the cyclic and collective pitch control determines the movement of the helicopter, the engine RPM does not need to be adjusted like an airplane engine does. So during normal flying, constant engine speed (RPM) is maintained and the pilot only needs to 'fine tune' the throttle settings when necessary. There is, however, a direct correlation between engine power and yaw control in a helicopter - faster spinning main rotor blades generate more torque, so greater pitch is needed in the tail rotor blades to generate more thrust.

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It's worth noting that each separate control of a helicopter is easy to understand and operate; the difficulty comes in using all controls together, where the co-ordination has to be perfect! Moving one control drastically effects the other controls, and so they too have to be moved to compensate. This continuous correction of all controls together is what makes flying a helicopter so intense. Indeed, as a helicopter pilot once said... "You don't fly a helicopter, you just stop it from crashing"!

Electric coaxial rc helicopters, sometimes referred to as dual-rotor or contra-rotating helicopters, have been responsible for bringing thousands of new people into the hobby of radio control flying in the last few years, and it's easy to see why.Coaxial rc helicopters are veryeasy to fly, and their inherentstability in the air makes them perfect first-time helicopters. Of course, they're not limited to new pilots; very experienced rc helicopter pilots are having a great deal of fun with coaxial helicopters too!Shown below are a couple of the most popular coaxials currently available, the Blade CX3, left, and its mega-successful predecessor the Blade CX 2, right, both from E-flite, a well respected name in beginner electric rc helicopters: Coaxial rc helicopters like the Blade CX2 and CX3 come RTF, or 'Ready To Fly', and can be flown with confidence pretty much straight from the box. They are much much easier to master than a conventional helicopter that has a single main rotor and tail rotor, and are equally capable of holding a steady hover - steadier, in fact. Flying them indoors is a realistic option, because their stability makes them easy to control within confined spaces.

See the Blade CX2 and CX3 in more detail here.

Coaxial RC helicopters

A conventional helicopter has a single main rotor consisting of two or more blades. When the rotor turns, a natural force called torque is generated. This torque makes the helicopter fuselage turn in the opposite direction to the

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spinning blades in a similar way to when you twist something up, it naturally wants to untwist itself.To counteract this force, a tail rotor is used to generate sideways thrust to push against the fuselage rotation. This prevents the helicopter from spinning wildly out of control.The amount of thrust generated by the tail rotor can be changed, either by altering the pitch angle of the tail rotor blades or, on smaller models, by changing the speed of the tail rotor motor. This change in thrust controls theyaw of the helicopter ie which direction the nose is pointing, by either giving in to the natural reaction against the torque (lessening tail rotor thrust) or by pushing the helicopter round in the same direction as the main blades (increasing the thrust).

The illustration below shows these basic forces at work: However, coaxial rc helicopters don't have a tail rotor, and instead of a single rotor they have two main rotors, one mounted directly above the other. These 2 main rotors spin in opposite directions to each other, as the illustration below shows:

Because the blades are spinning against each other, each one cancels out any torque generated by the other one. As a result, there is no tendency for the fuselage of the helicopter to spin round one way or the other.This is only the case, however, so long as both sets of blades are spinning at exactly the same speed. As soon as one set changes speed relative to the other one, then torque immediately appears. This is exactly how yaw is controlled in coaxial rc helicopters, by making one set of blades spin faster or slower then the other set, to purposely generate torque which will cause the helicopter to change direction. In most coaxial rc helicopters, the top blades are mounted on the main shaft and the lower blades are mounted on a larger diameter hollow shaft that runs up outside of the main one. Twin side-by-side electric motors control one shaft each, and hence independent rotor speed control is possible. The picture to the right shows a typical coaxial setup for the main drive gear, with each motor cog driving one of the main sprockets. This photo is of the Blade mCX.

Coaxial rc helicopters are, without doubt, the easiest and safest way of getting into the hobby of flying radio control helicopters, and they're suitable for anyone, regardless of helicopter-flying experience. They can easily be flown indoors, but are equally suited to outdoor flying also.

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Full size coaxial helicopters

You could be forgiven for thinking that rc helicopters with two sets of rotors are completely fictitious designs, and unique to the radio control world, but there are a number of such full size helicopters. The Russian helicopter manufacturer Kamov have produced several dual rotor helicopters for both civilian and military use, the KA32 shown below is one such example:

There's also a safety factor with coaxial helicopters; no tail rotor means less danger when the helicopter is on the ground. And in flight, a failing tail rotor will almost definitely cause the helicopter to come down out of control. No tail rotor eliminates this risk.

The transmitter... The tx is very 'plasticy' but it does the job, and it's fairly typical of all transmitters sold with 4-channel RTF electric helicopters these days. You need to purchase 8 AA size batteries to operate it - you can use good qualitydry cells or rechargeables. I use 700mAh NiMH batteries, and there is a charging socket in the back of the tx that accepts a standard tx charging plug. Incidentally, the tx battery holder is removable with a 2-pin JST connector.The battery level indicator is in the top/center of the tx face. 10 vertical bars increase in height from left to right and when the tx is switched on they illuminate over a range of red (left), orange (middle) to green (right). Obviously you want the green to be there - if they stop at orange then your batteries are in borderline condition, and if only the red is showing then you need to replace/fully recharge them.You'll need to screw the antenna into the top of the tx body - a fairly straightforward task. No need to get the pliers onto it, just screw it in as tight as you can get it by hand.

A good route from the rx is: down the left front leg, along the left skid, up the left rear leg and out along tail boom. Tape it in position just before the point where the tail rotor tip is at its most forward. From here, coil it round the tail boom back towards the canopy, run it down the right rear leg and

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wind the remaining amount of antenna round the right skid. Use tape on the tail boom and tape or small bands of heat shrink tubing (don't heat shrink them though!) to hold the antenna in place on the skids...

Whatever you do, don't cut the antenna! This drastically reduces the radio range of the model, with disastrous consequences. Any antenna that is left over, just wrap around the skid as in the picture above.Helicopter Center of Gravity (CG)...The next very important thing to do is to check the balance of the helicopter itself - a badly balanced heli will be at best difficult to fly, and at worst completely uncontrollable.The helicopter's center of gravity (CG) is at the main rotor shaft, and its balance is influenced by the position of the battery pack - so you'll have to do this step with the pack in position on the heli.

Rotate the flybar so that it is perpendicular to the fuselage and lift the helicopter off the ground, with the flybar resting on the tips of your two index fingers, one just each side of the rotor head assembly.Also at this point, make sure that you've got the rubber band on the cage to prevent the two halves sliding apart.

If, at this point, the battery is as far forward as it will go and the helicopter still hangs with its tail down, add some weight to the nose of the helicopter canopy - small coins, fishing shots or modeling clay make good ballast.

The disadvantage with adding nose-weight is that it adds to the whole weight of the helicopter, which reduces flight times because more power is needed. But, a marginally shorter safe flight is better than an out-of-control one in my opinion!Fit heat sinks...Finally, as an option, you might want to consider fitting heat sinks to both motors. On this kind of rc helicopter, the tail motors especially are prone to burning out and heat sinks are a good way to help prolong the motor life. They clip around the motor body and carry heat away from the motor itself - they're not available for the Dragonfly 4 specifically but the eSky EK10223 &EK10224 fit the Dragonfly motors, with a tiny amount of bending.

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Fitting training skids...Electric rc helicopter training skids are a great idea and are definitely worth the few dollars that they cost. They may not look too flattering, but they do prevent possible damage which can result from the helicopter tipping over in a bad landing.

The standard kit includes 4 skids, each one a carbon fiber leg with a plastic ball at the end. There is also a central hub and 4 attachments that clip over the main skids of the helicopter, at the joint of the skid and leg.

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Being the PNP version there was a notable absence of Tx, charger and motor battery pack - the only items to accompany the helicopter in the box were the instruction manual and a small plastic bag of tools and accessories (allen keys, screwdriver, zip ties...).Initial inspection of my E-flite Blade 400 revealed a definite 'quality' feel to it and it looked to be a very well thought out heli indeed. The positioning of all the components was good, and access to all the crucial parts looked relatively unimpeded. The helicopter felt solid too, certainly not a cheap n' cheerful model that was going to fall to pieces after three flights! Of course, being 3D capable the Blade 400 has been designed and manufactured accordingly, hence its solid feel. It's a nice size too, a typical 'class 400' electric rc CP helicopter.

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Above, a very well thought out and not overly complicated heli, I think!

Now, the fact that the E-flite Blade 400 is 3D capable doesn't mean that mine is ever likely to see any 3D action! The fact that this is my very first Collective Pitch rc helicopter means that mastering straightforward flight is the number one priority, and the fact that I can do a few basic 3D maneuvers on the simdoesn't mean that I'll ever have the nerves to try them for real!Anyway, back to the setting up... I had chosen to go with the same receiver for my PNP version heli that the RTF one is sold with, the Spektrum AR6100e. Following the manual's guidelines, installation of the Rx was very straightforward - some double-sided sticky tape and a small zip tie did the job of holding the receiver comfortable in place on the base of the main frame, behind the ESC.The other crucial component not supplied with a PNP aircraft is of course a motor battery pack, but fortunately I already had a suitable pack (2100mAH 11.1V 3S) ready for action. Although marginally larger and heavier than therecommended E-flite pack, it fits perfectly well in place, held securely by the velcro strip and strap.

Above, my 'FlyPo' pack and the receiver (arrowed yellow) in place

Time to spool up!

As I said earlier, I'm not a complete newbie to rc helicopters but this E-flite Blade 400 was an entirely different beastie to anything I'd flown before. Following the invaluable advice given in John Salt's excellent eBook "Setup & Tips for 400 Size RC Helicopters", I invested in a set of rc helicopter training gear, reduced the Pitch and throttle Curve settings from the factory-set default 3D values (essential if you want to keep your heli in one piece!) and prepared my nerves for action...Doing exactly what you shouldn't do, I placed my heli in a small, enclosed space (our laundry area!) knowing full well that the downwash created by the spinning main blades wouldn't get cleared away because of the four walls closely surrounding the helicopter, but instead would cause havoc with the heli's stability. But I justified this potentially dangerous decision simply because I knew that I could hover an FP helicopter without problem, and could hover a CP one on the sim.

On spooling up the Blade 400, my initial surprise was at the noise of those 325mm blades. Wow, impressive! Of course, the sound was amplified because of the four walls but it sounded great, more like a real helicopter than a model one!

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The next thing I had to get used to was that I could have the blades spinning at speed without the heli lifting, in total contrast to a Fixed Pitch helicopter that starts to lift as soon as the main blades pick up any speed. So, with the 400 sat there, blades spinning and my heart pounding, I slowly increased the throttle stick to start introducing some positive pitch and the helicopter gracefully lifted off the ground. A small amount of right cyclic was needed to counteract the left drift caused by the tail rotor, but I had anticipated this being the case so was fully prepared. 

Military service

Weaponised HAL Dhruv helicopter.

Deliveries of the Dhruv commenced in 2002, a full ten years after the prototype's first flight, and nearly twenty years after the program was initiated. The Indian Coast Guard became the first service to bring Dhruv helicopters into service. This was followed by the Indian Army, Indian Navy, Indian Air Force and the Border Security Force. Seventy five Dhruvs were delivered to the Indian armed forces by 2007 and the plan is to produce forty helicopters yearly. One of only three helicopter display teams in the world, the Sarang aerobatic display team of the Indian Air Force performs with four Dhruv helicopters.

The Dhruv is capable of flying at high altitudes, a crucial requirement for the Army, which requires helicopters for operations in Siachen Glacier and Kashmir. In September 2007, the Dhruv was cleared for high-altitude flying in the Siachen Sector after six-month long trials.[6][7]. In October 2007, a Dhruv flew to an altitude of 27,500 feet (8,400 m) ASL in Siachen. This was the highest that the Dhruv had flown, and was higher than the 25,000 feet (7,600 m) record set by an IAF Cheetah helicopter in 2005.

A further order for 166 helicopters were placed with HAL since the helicopter is working well in higher altitude areas with the Indian Army TheArmed Forces may order 12 ambulances versions for use by the Armed Forces Medical Services for MEDEVAC operations . HAL Dhruv ambulances will have all the emergency medical equipment for the treatment of injured soldiers. In June 2008, the Hindustan Times reported that the Indian Navy had decided against placing further orders for the Dhruv Naval variant, stating it has failed to meet basic operational requirements However

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these rumours were put to rest by the recent comments of the defence minister who stated in the parliament that the navy had not rejected the dhruv as eight Dhruv helicopters are already operating in the Utility role. The Anti-submarine version will not be inducted since it did not suit the requirements of the Indian Navy in anti-submarine role.

Civilian service

Civilian variant of HAL Dhruv.

HAL also produces a civilian variant of the Dhruv for VIP transport, rescue, policing, offshore operations and air-ambulance role, among others.

In April 2008, HAL chairman Mr Baweja confirmed that the Home Ministry had "placed an order for six ALHs"

The National Disaster Management Authority (NDMA) has placed an order for 12 Advanced Light Helicopters (ALH) with Hindustan Aeronautics Limited (HAL). Chief Test Pilot Wing Commander Upadhyay said the helicopters will have a full set of medical equipment, including ventilators and two stretchers.

Other buyers include the Geological Survey of India (GSI) (1 Helicopter), ONGC for its offshore operations, as well as state governments for VIP transport and policing.

Foreign sales

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Dhruv helicopters of the Ecuadorian Air Force

A Dhruv helicopter of the Maldives National Defence ForceThis file is a candidate for speedy deletion. It may be deleted after Tuesday, 4 May 2010.

The Dhruv has become the first major Indian weapons system to have secured large foreign sales. HAL hopes to sell 120 Dhruvs over the next eight years,and has been displaying the Dhruv at airshows, including Farnborough and Paris in order to market the Dhruv.

With a unit price at least 15% less than its rivals, Dhruv has elicited interest in many countries, mostly from Latin America, Africa, West Asia, South East Asia and the Pacific Rim nations. Air forces from around 35 countries have sent in their inquiries, , along with requests for demonstrations.

The first foreign orders for the Dhruv were placed by Nepal in early 2004, for 2 Dhruvs. Another Dhruv, a civilian version, was leased to the Israeli Defense Ministry in 2004

In June 2008, the government of Peru ordered two air ambulance Dhruvs for use by the Peruvian health services. Peru has also shown interest in the military version Dhruv.

HAL also secured an order from the Ecuadorian Air Force for seven Dhruvs. HAL has gained this order amidst strong competition from Elbit, Eurocopter and Kazan. HAL’s offer of $ 50.7 million for seven helicopters was about 32% lower than the second lowest bid from Elbit. Five helicopters will be delivered in February 2009, during the Aero India 2009. The remaining two helicopters will be delivered within six months. Ecuadorian Army and Ecuadorian Navy have also expressed unofficial interest in purchasing the helicopter.

On August 10, 2008 HAL chairman confirmed it had finalized a deal with Turkey to supply 3 Dhruvs for $20 million. Turkey is planning to buy as many as 17 helicopters in medical assistance role.

India is also reportedly planning to transfer several Dhruvs to Burma. This led to protests from Amnesty International, who pointed to the use of

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components sourced from European suppliers as a possible violation of the EU Arms Embargo of Burma. In a letter to the President of the EU Council of Ministers, Amnesty stated that it had evidence that India planned to transfer two Dhruvs (with European components) to Burma. These reports have been denied by the Indian Government .

Attack helicopter

An AH-64 Apache helicopter of the U.S Army

An attack helicopter is a military helicopter specifically designed and built to carry weapons for attacking targets on the ground, such as enemy infantry, armored vehicles and structures. Weapons used on attack helicopters can include autocannons, machine-guns, rockets, and guided missiles such as the Hellfire. Many attack helicopters are also capable of carrying air to air missiles, though mostly for purposes of self-defense. Today's attack helicopter has two main roles: first, to provide direct and accurate close air support for ground troops, and the second, in the anti tank role to destroy enemy armor concentrations. Attack helicopters are also used to supplement lighter helicopters in the armed scout role.

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Air ambulance

Air ambulance

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An air ambulance helicopter landing in a car park

An air ambulance is an aircraft used for emergency medical assistance in situations where either a traditional ambulance cannot reach the scene easily or quickly enough, or the patient needs to be transported over a distance or terrain that makes air transportation the most practical transport. These and related operatations are referred to asAeromedical. Air ambulance crews are supplied with equipment that enables them to provide medical treatment to a critically injured or ill patient. Common equipment for air ambulances includes ventilators, medication, an ECG and monitoring unit, CPRequipment, and stretchers.

Air ambulances were useful in remote areas, but their usefulness in the developed world was still uncertain. Following the end of the Second World War, the first civilian air ambulance in North America was established by the Saskatchewan government in Regina, Saskatchewan, Canada, which had both remote communities and great distances to consider in the provision of health care to its citizens. The Saskatchewan air ambulance service continues to be active as of 2009.

Back in the United States, 1947 saw the creation of the Schaefer Air Service, the country's first air ambulance service. This service was founded by J. Walter Schaefer, of Schaefer Ambulance Service in Los Angeles, California. Schaefer Air Service was also the first FAA-certified air ambulance

service in the United States. At the time of the creation of the Schaefer and Saskatchewan

services, paramedicine was still decades away, and unless the patient was accompanied

by a physician or nurse, they operated primarily as medical transportation services. A

great deal of the early use of aircraft as ambulances in civilian life, particularly

helicopters, involved the improvised use of aircraft belonging to branches of the military.

Eventually this would become more organized. This mode of usage occurred not only in

the United States, but also in other countries, and persists to this day.

Military Aircraft Supporting Civilian Air Ambulance

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Swedish Search and Rescue

Dutch Search and Rescue

Israeli Military Helicopter as Air Ambulance

Two programs were implemented in the U.S. to assess the impact of medical helicopters on mortality and morbidity in the civilian arena. Project CARESOM was established in Mississippi in 1969. Three helicopters were purchased through a federal grant and located strategically in the north, central, and southern areas of the state. Upon termination of the grant, the program was considered a success and each of the three communities was given the opportunity to continue the helicopter operation. Only the one located in Hattiesburg did so, and it was therefore established as the first civilian air medical program in the United States. The second program, the Military Assistance to Safety and Traffic (MAST) system, was established in Fort Sam Houston in San Antonio in 1969. This was an experiment by the Department of Transportation to study the feasibility of using military helicopters to augment existing civilian emergency medical services. These programs were highly successful at establishing the need for such services. The remaining challenge was in how such services could be operated most cost-effectively. In many cases, as agencies, branches, and departments of the civilian governments began to operate aircraft for other purposes, these aircraft were frequently pressed into service to provide cost-effective air support to the evolving Emergency Medical Services.

Government operated

Scottish Ambulance Service - The UK's only Government funded air ambulance service.

In some cases, air ambulance services will be provided by government, either directly or by means of a negotiated contract with a commercial service provider, such as an aircraft charter company. Such services may focus on the transfer of critical care patients, may support ground-based EMS on scenes, or may perform a combination of these roles. In almost all

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cases, the government will provide guidelines for use to both hospitals and EMS systems, in order to keep operating costs under control, and may specify operating procedures in some level of detail in order to limit potential liability, but almost always takes a 'hands-off' approach to the actual running of the system, relying instead on local managers with subject matter (physicians and aviation executives) expertise. Ontario's ORNGE program and the Polish LPR are examples of this type of operating system. In North East Ohio, including Cleveland, the Cuyahoga County-owned MetroHealth Medical Center uses its Metro Life Flight to transport patients to Metro's level I trauma and burn unit. There are 5 helicopters for North East Ohio and, in addition, Metro Life Flight has one fixed-wing airplane.

Reference

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REFERENCE FOR ARTICLES & TECHNICAL INFORMATION ON REMOTE

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