Snelflight Hoverfly Instructions for use

Instructions

and

Maintenance Manual

Issue 2.6

Hoverfly

INTRODUCTION

Congratulations on purchasing your Hoverfly, and welcome to the enchanting world of indoor

electric flight! The Hoverfly is truly ahelicopter in miniature. It can hover mesmerically in front of

you, then dart off in any direction before hanging motionless in the air once more. It can dive

swiftly downwards and swoop back up, or dance in graceful figures-of-eight whilst performing

pirouettes.

The Hoverfly's unique and patented Electrocyclic control system gives it an unmatched

combination of rugged mechanical simplicity and authenticity in its representation of larger

models. Since the Hoverfly is mains-powered, it can fly continuously and, best of all, it comes

ready to fly, right out of the box.

The only setting up needed is to configure the Hoverfly's control system to your particular

transmitter. We strongly suggest that you take the time to follow carefully the set-up procedure

given in this manual, since this not only offers the best chance of asuccessful first flight, but also

allows you to gain valuable insight into the Hoverfly's unique features, behaviour and capabilities.

In the majority of cases some sections of the Manual can be skipped, and set-up will be completed

in just afew minutes. The Hoverfly is different to all previous model helicopters, and a little time

spent getting well acquainted with it now will be amply rewarded.

Have fun!

Please note: Hoverfly is designed for trouble free flying, but for

continued top perfomance, alittle routine maintenance is

recommended. See Section 14 for details.

IMPORTANT NOTICE

Hoverfly is not atoy. It is an engineered model which although

light in weight is capable of causing damage or injury if operated

irresponsibly, primarily due to contact with the three thrust

propellers. Avoid flying close to people or pets.

It may start up violently if the instructions contained in this

manual are not followed, or if afault occurs. To be sure of

avoiding damage or injury always hold the centre of the rotor

(keeping clear of the propellers) when switching on the mains

power.

The motors become hot in use; to avoid injury do not touch until

cool.

Unplug from the mains supply when not in use. Do not use in

the wet.

4. HANDLING THE HOVERFLY

The Hoverfly should be held by the centre of the rotor, grasping

it from above by the green printed circuit disc immediately

below the rotor hub (Photo 1). Do not lift by the black dome,

which pulls off easily. Alternatively, it can be held by the black

plastic chassis, immediately above the undercarriage (Photo 2).

On no account should it be held by the body or tail boom.

Carefully lift the helicopter out of the box and place it on the

floor. Uncoil the command line, taking care to avoid kinking it,

guiding it away from the model rearward to ensure it will not

foul the undercarriage or tail. Do not allow the line to become

kinked. Sharp bends will weaken it and must be avoided. (See

also Section 14K).

We suggest that newcomers to model helicopters should read

Section 12 entitled Helicopter Principles before carrying on.

CONTENTS OF THE MANUAL

Section Section Section

Please read it carefully before attempting to fly the model.

It comes with its thin command line already attached.

This is the unit with ablack lead attached. It converts power from the mains into 34V d.c.

to power the model.

This is the black box with three electrical connectors. It hooks up to the trainer socket of a

radio control transmitter, and converts its signal into aform suitable for the Hoverfly.

These are used to connect the ECP to asuitable R/C transmitter. One lead is fitted with a

DIN plug, and is suitable for Futaba and Hitec transmitters. The other lead has a3.5mm

jack, and is suitable for JR and some Sanwa transmitters.

This is specially selected as amatch for the three propellers fitted to the Hoverfly. Its

packaging carries asingle digit thrust number.

Two lightweight tubes to attach to the skids whilst learning to fly.

Hook for threading the tail drive belt during maintenance.

For convenient, safe storage of the Hoverfly's command line.

For you to customise your Hoverfly.

13. Overview of the Hoverfly.

14. Maintenance.

15. Fitting the Window and Decals.

16. Tips and Troubleshooting.

17. Specifications.

18. Spares.

7. Non-Standard Transmitters.

8. Setting Control Trims.

9. Commissioning.

10. Pre-Flight Checks.

11. Your First Flight.

12. Helicopter Principles.

1. Introduction

2. Packing List

3. Additional Items Required.

4. Handling the Hoverfly.

5. Connections and Transmitter

Settings.

6. Channel Assignment.

Photos 1and 2: How to hold the Hoverfly.

3. ADDITIONAL ITEMS REQUIRED

The only additional item required is acontrol unit of the type

normally used for radio control of models. If you are intending

to move on to larger helicopters when you have qualified using

the Hoverfly you may decide to invest in atransmitter with

more features than the minimum listed below.

Minimum transmitter specification.

lFour control channels with two twin-axis (gimballed) joy-

sticks.

lFitted with atrainer (buddy box) socket, using PPM (pulse

position modulation) signalling.

lReversing switches on at least the first four channels.

lThe transmitter should preferably use either the Futaba, JR,

Hitec or Sanwa systems. Hoverfly will work with many

others but the set-up procedure is more complicated.

2. PACKING LIST

This Manual:

The Helicopter:

Power Supply (with detachable

mains lead):

Electrocyclic Control Processor

(ECP):

Signal Leads (2):

Spare Propeller:

Trainer Undercarriage:

Belt Insertion Tool:

Command Line Reel:

Decals, Stripes and Moulded

Window:

Once you have the right lead, the equipment should be

connected up as in Fig. 5-1, with the exception of the

Hoverfly itself, which should not be connected yet.

Because the transmitter connects directly to the ECP, no radio

communication is necessary. The transmitter's batteries are still

needed to generate the signal at the trainer socket, but their

lifetime is greatly increased, and there are no frequency

conflicts or interference problems to worry about. It is therefore

important to make sure that the transmitter's radiofrequency

section is shut off when operating the Hoverfly. With some

transmitters, the act of plugging in the trainer cord automati-

cally switches on the power, whilst simultaneously turning off

the radiofrequency circuitry. If this happens, the main power

switch should be left in the off position. With other units, the

power switch must be turned on, but the radiofrequency section

should be disabled by removing the crystal.

The following settings and checks should now be made.

a) Signal Mode Selection: If your transmitter offers PCM as

well as PPM signalling, switch it to PPM. THIS IS VERY

IMPORTANT. PCM-only transmitters cannot be used with

the Hoverfly, but these are fortunately very rare. Attempting to

operate in PCM mode will cause the Hoverfly to start violently

as soon as the power is switched on.

b) Servo Travel: If your transmitter has adjustable servo travels

(endpoint adjustments), set the first four channels to 100% in

both directions of throw. Exponential joystick response can be

selected if you wish.

c) Channel Centres: If your transmitter has channel centre

adjustments, these should be set to zero (centred) on the first

four channels. The external trim tabs should also be centred.

d) Mixing Functions: If your transmitter has mixing functions,

such as Throttle to Rudder mixing, these should be switched

off, or set to zero.

e) Throttle Curve: If your transmitter has athrottle curve

feature, it should be set up to give afull range, linear throttle

response. Make sure that the Throttle Hold switch is turned off,

too. Some transmitters have an Aeroplane mode, in which these

functions are de-activated. It is usually easier to use this mode

with the Hoverfly.

f) Some transmitters have mechanical stops on the throttle

stick, which limit movement to less than 100%. This reduces

the available Collective range on the Hoverfly, making

climbout sluggish. It is easy to see if atransmitter has these

stops, by comparing the physical positions of the left and right

sticks when pushed fully forwards (or backwards). The stops

typically reduce throttle throw by about 20%. We offer the

following solutions:

5. CONNECTIONS &TRANSMITTER SETTINGS

In order that the Hoverfly controls will work correctly with the

particular type of transmitter being used, both the Electrocyclic

Control Processor (ECP)and the transmitter itself have to be

set up correctly. For simplicity of setting-up, we recommend

using one of the following Standard types of transmitter:

FUTABA HITEC JR SANWA

This is because these popular types can be set up according to

the simple tables in this manual. Other types can be used, but it

will be necessary to use aspecial procedure to determine the

correct set-ups, since there are agreat many different systems,

which could not all be included here.

Connecting the transmitter to the Hoverfly system.

The transmitter communicates with the Hoverfly by way of an

interface unit, the Electrocyclic Control Processor (ECP),

which is the small black box with electrical sockets at each

end. This unit interprets the signal from the transmitter and

uses it to control the amount of power sent to each of the

motors on the Hoverfly. By varying the power levels in the

right combinations, all the flight control functions of a

conventional helicopter are created.

The transmitter connects to the ECP by means of asignal lead,

of which two types are supplied with the Hoverfly. These leads

allow connection of Futaba, Hitec, JR and some Sanwa

transmitters. The lead is used to connect the transmitter trainer

socket to the Signal socket on the ECP. For Futaba and Hitec

transmitters, use the lead with the six-way DIN plug; for JR

and Sanwa transmitters, use the lead with the 3.5mm jack plug.

NOTE ON SANWA TRANSMITTERS: Sanwa have fitted a

variety of different training sockets to their transmitters. Early

Vanguard models use a3.5mm jack socket; these will work

with the lead supplied, and all set-ups are the same as for JR.

More recent Vanguards have asix-way DIN socket. These will

NOT work using the Futaba/Hitec lead, because Sanwa use

different pins in the DIN plug. The rest of the set-up procedure

for these transmitters is, however, the same as for JR. More

recently still, the RD6000 transmitter has been introduced, and

this uses afive-way DIN socket. It is compatible with

Airtronics products sold in the United States, and has to be set

up differently. The details are included here. Snelflight can

supply special leads for these various transmitters.

NOTE ON NON-STANDARD TRANSMITTERS: The great

majority of transmitters can be used with the Hoverfly.

However, we recommend caution in the use of the Futaba/Hitec

lead for connecting up other makes, even if your unit appears to

have exactly the right type of socket. This is because some of

the pins are connected together inside the DIN plug, and the

transmitter may be damaged if these pins happen to carry

electrical signals which conflict. If your transmitter has a

3.5mm jack socket, it will generally be safe to try the JR/Sanwa

lead, but if you are in any doubt, we recommend that you

contact Snelflight for advice. We can arrange to supply a

suitable lead in most cases. We are constantly seeking to

expand our database on trainer leads and set-ups; we therefore

welcome information on unusual ones.

Fig. 5-1

6. CHANNEL ASSIGNMENT

WARNING: NEVER SWITCH ON THE POWER WHILST

THE HOVERFLY IS CONNECTED UNLESS YOU ARE

SURE THAT THE CHANNELS ARE PROPERLY

CONNECTED AT THE PATCH SOCKET. ESPECIALLY,

DO NOT SWITCH ON OR ATTEMPT TO FLY WITH SOME

CHANNELS UNCONNECTED. UNCONNECTED

CONTROL FUNCTIONS WILL HAVE UNDEFINED

VALUES, AND WILL BEHAVE UNPREDICTABLY. THE

HOVERFLY MAY START UNEXPECTEDLY. BE

CAREFUL!

The Hoverfly has four flight control functions; Collective,

Aileron, Elevator and Rudder. Each of these is associated with

one of the four axes of joystick movement provided on the

transmitter. Information about the positions of the joysticks at

any moment is sent to the ECP by means of four transmitter

channels, one for each flight control function. On any

transmitter, these will always be the first four channels,

regardless of the total number of channels the transmitter has.

It is of course important to ensure that each flight control

function is operated by the correct joystick. On aconventional

model, this is done by connecting each control servo to the

appropriate channel on the radio receiver. Because the Hoverfly

has no receiver or servos, aChannel Patch Socket is provided

within the ECP for this purpose. This has two rows of four

electrical terminals. Channels 1, 2, 3and 4from the transmitter

i) On computer transmitters, the throttle channel endpoint

adjustments can be set to 120% (in both directions) to

compensate for the reduced stick movement.

ii) On more basic transmitters, the throttle trim can be

pushed forwards to compensate for the reduced upper

joystick range. Unfortunately, this compounds the prob-

lem at the bottom end, and often means that the

Hoverfly doesn't shut off completely unless the trim is

returned to the centre.

iii) As alast resort, the mechanical stops can usually be

removed. They often take the form of wedge shaped

pieces of plastic, which are screwed to part of the

gimbal mechanism. By carefully comparing the left and

right stick mechanisms, the culprits can generally be

spotted. Because this involves opening the transmitter,

it may affect the manufacturer's warranty, but it is

normally only necessary on inexpensive transmitters

without endpoint adjustments. The stops can usually be

put back later, if needed.

g) Now switch on the mains supply: The red Power light should

illuminate on the ECP.

h) Switch on the transmitter (if not automatic): The green

Signal light should illuminate on the ECP after approximately

2seconds delay.

Now switch everything off. (Remember that some transmitters

remain on until the trainer plug is removed).

For successful set-up, the steps in Sections 6 to 8must now

be completed. Please follow them carefully.

arrive at the terminals on the left, whilst those on the right lead

to the flight control functions C, A, Eand R(Collective,

Aileron, Elevator and Rudder). The Patch Socket allows the

flight control functions to be connected to the four channels in

any combination, so that awide variety of transmitter types can

be used with the Hoverfly.

To gain access to the Channel Patch Socket, it is necessary to

open the ECP (see Section 14L for instructions). Fig. 6-1 shows

the location of the Patch Socket. Patching is done using four

black link wires, which plug into the socket terminals. Text on

the circuit board identifies each terminal. The links may be

crossed over each other, but each link must connect across the

socket, linking achannel to acontrol function, and when the

set-up is complete all four links must be in place.

Fig. 6-1 Location of Channel Patch Socket

Mode 1and Mode 2Operation.

The terms Mode 1and Mode 2refer to the two joystick

arrangements commonly used by model helicopter pilots.

Mode 2is more popular and is described first. Information on

Mode 1operation is included at the end of this section.

Fig. 6-2 shows how the controls are laid out in Mode 2.

Fig. 6-2 Mode 2Control Layout.

The ECP comes factory preset for Mode 2operation with

Futaba and Hitec transmitters. To set up Mode 2for one of the

other Standard transmitter types, simply pull out the four link

wires, and plug them back in according to the diagrams below.

Always switch off the power before removing or inserting

the link wires. The electronics can be damaged if anything

metal touches the circuitry whilst the power is on.

Mode 2Patch Links

NOTE: These set-ups assume that the transmitter channel

sequence is as per the manufacturer's standard. Some

computer transmitters allow the channel sequence to be

changed by the user, and this will cause incorrect operation of

the Hoverfly. It is vital that the transmitter itself is set up in the

standard way. Many models have aprocedure for restoring the

factory settings. More basic transmitters are actually easier to

use with the Hoverfly!

Setting the Servo Reverse Switches.

After setting up the Patch Socket, it is necessary to set the

correct direction of movement for each channel. This is done by

means of the transmitter servo reverse switches. These must be

set according to Table 6-1 below.

Table 6-1 Reverse Switch Settings

MODE 2

PATCH LINKS

FUTABA

HITEC

SANWA VANGUARD

SANWA RD6000

Mode 1Operation.

The majority of pilots wishing to fly in Mode 1(throttle on the

right) format either use atransmitter which has been

specifically supplied as aMode 1unit, or one which has a

Mode 1option built-in. In such cases, the Hoverfly set-ups will

be the same as for Mode 2. On occasions however, the owner

may convert aMode 2transmitter to Mode 1mechanically, by

transferring the return spring from one joystick to the other. As

aresult, the Throttle signal occupies the channel originally

assigned to the Elevator, and vice versa. To fly the Hoverfly

with such atransmitter, the Patch Socket should be set up as

below. Fig. 6-3 shows how the controls are laid out in Mode 1.

Mode 1Patch Links

Fig. 6-3 Mode 1Control Layout

Setting the Servo Reverse switches.

After setting up the Patch Socket, it is necessary to set the

correct direction of movement for each channel. This is done by

means of the transmitter servo reverse switches. The settings

are the same as for Mode 2, and are given in Table 6-1.

MODE 1

PATCH LINKS

FUTABA

HITEC

SANWA VANGUARD

SANWA RD6000

Futaba

Hitec

Sanwa(inc

RD6000)

Normal

Reversed

Normal

Reversed

Normal

Reversed

Normal

Reversed

Channel 1234

change the setting of the transmitter servo reverse switch (for

Channel 1in this example), and try again. Make anote of the

correct switch setting.

vi) Switch off, pull out the Patch Socket link wire and use it to

connect Channel 2to the Rudder terminal. Repeat steps iv)

and v) for this channel, then likewise for Channels 3and 4.

vii) Complete the Patch Socket set-up, using the connections

noted above. Insert the four link wires in the required positions,

and make anote of the set-up on the diagram below, for future

reference.

Reverse Switch Positions and Patch Socket Set-Up

7. NON-STANDARD TRANSMITTERS

Assigning Channels and Setting the Transmitter Servo

Reverse Switches.

If you are using aStandard transmitter, please skip this section

and move on to Section 8.

If your transmitter is not one of the Standard types with set-ups

given in Section 6, it will be necessary to carry out aspecial

procedure to determine the correct settings for both the ECP

Patch Socket, and the transmitter servo reverse switches. The

ECP has facilities which allow the correct set-ups to be

determined before the Hoverfly is ever connected, making the

process relatively straightforward.

Two small LEDs, located on either side of the Control Trim

Adjuster (Fig. 6-1), are connected by circuitry in the ECP to the

Patch Socket Rudder (R) terminal. They indicate when the

Rudder is pushed to the left (red LED), or to the right (green

LED), or centred (neither LED). They will be used later to trim

the ECP.

These LEDs have another important function. They allow the

operation of any of the four channels to be monitored, simply

by connecting the channel in question to the Rudder terminal in

the Patch Socket, using one of the black link wires. The

Rudder terminal is the only one which works the LEDs,

giving it this special test function. Transmitter channels

can be checked, ONE AT ATIME, by linking them to the

Rudder terminal.

ALWAYS SWITCH OFF THE POWER WHILST CHANGING

THE PATCH SOCKET CONNECTIONS. TAKE GREAT

CARE WHEN THE POWER IS ON, BECAUSE DAMAGE

TO THE ELECTRONICS CAN EASILY OCCUR IF ANY-

THING METAL TOUCHES THE CIRCUIT BOARD OR

COMPONENTS.

These LEDs can be used to determine the correct Patch Socket

set-up. The procedure we suggest is given below. You will

need apen and paper.

i) Begin by connecting everything up as in Fig. 5-1, with the

exception of the Hoverfly itself, which should not be

connected yet. Switch everything on, and check that the green

Signal light illuminates on the ECP. Now switch off the power

to the ECP, but leave the transmitter on.

ii) Remove all four link wires from the Patch Socket.

iii) Connect Channel 1to the Rudder (R) terminal, using one of

the link wires.

iv) Switch the power to the ECP on, and wiggle the transmitter

joysticks to find out which of the four axes of movement

operates the LEDs. Make anote of this. For example, Elevator

joystick movement might work the LEDs, in which case note

down that Channel 1is Elevator. If the LEDs do not respond at

all, check that the transmitter is set to PPM signalling.

v) Using the table below, check whether the joystick works in

the right direction for the Hoverfly. For instance, the Elevator

stick should light the red LED when pushed forwards, and the

green LED when pulled back. If the direction is incorrect,

8. SETTING CONTROL TRIMS (NEUTRAL

POSITIONS)

The final adjustment required is to set the control trim, so that

each function is at neutral when the joysticks are centred.

There is asingle adjustment inside the ECP for this purpose,

which sets the trim for all four channels at the same time. This

control is located close to the Patch Socket (Fig. 6-1). On either

side of it are two small indicator LEDs, already discussed in

Section 7. One of these may be lit. The trim is set as follows:

i) Connect everything up as in Fig. 5-1,with the exception of

the Hoverfly itself, which should not be connected yet.

ii) Switch on the transmitter and the ECP. The red Power light

should come on, followed by the green Signal light.

iii) Centre all the trim tabs on the transmitter. If the transmitter

has electronic sub trims, these MUST be set to zero as well, on

all four channels.

iv) Use asmall screwdriver to adjust the ECP trim control,

turning it towards the indicator LED that is lit. At some point

the LED will go out, and turning the control further will cause

the other LED to light up. Set the control to the centre of the

Stick

Aileron

Elevator

Direction

Left

Right

Forward

Back

Left

Right

Function

Left

Right

Nose down

Nose up

Left

Right

LED

Red

Green

Red

Green

Collective Forward

Backward Increase

Decrease Red

Green

Red

Green

Rudder

9. COMMISSIONING

Before attempting to fly the Hoverfly for the first time, it is

very important to check that it is operating properly. Incorrect

set-ups can cause the Hoverfly to start violently and unexpect-

edly, so steps i) to iv) of the following procedure are designed

to prevent mishap if this should occur. PLEASE FOLLOW

THEM CAREFULLY. Steps v) to x) allow you to try out the

Hoverfly's controls, and to familiarise yourself with its main

features and behaviour, some of which are unique. New pilots

should examine Fig. 6-2 (Page 5) carefully, to familiarise

themselves with the control layout.

i) Connect up the equipment as in Fig 5-1. Turn on the

transmitter, and set all the trim tabs to their central positions.

Set the collective stick to the zero position, which will normally

be fully towards you. Plug in the power supply, but DO NOT

turn on the mains yet.

'dark' zone. Take care not to touch any other components with

the screwdriver. If the LEDs do not respond, check the

transmitter settings again. PPM SIGNALLING MUST BE

USED.

v) Confirm that the ECP is operating correctly by moving the

Rudder stick from side to side. Pushing it to the left should turn

on the red LED, pushing it right should turn on the green one.

If this test fails, then all the connections should be checked

carefully, and the set-up procedure done again.

vi) If all is well, switch off the power to the ECP and the

transmitter. Since all settings are now complete, the ECP cover

should be carefully replaced (Section 14L).

NOTE: Now that the ECP has been trimmed, the transmitter

trim tabs can be used as required for fine adjustment of

aircraft trim.

NOTE ON OLD OR UNUSUAL TRANSMITTERS:

Although the ECP trim control adjusts the trim on all four

channels simultaneously, the LEDs only indicate the setting of

the Rudder channel. The trim control affects all channels

equally, and hence when the Rudder channel is set correctly,

they all are. This scheme does rely on the transmitter channels

being well matched; ie. all four transmitter channels should be

electrically equal when the transmitter trims are all centred.

This is true of all modern transmitters in our Standard list,

even the basic models, and is one reason why we recommend

them. However, we have noticed that some of the less popular

brands can be poor in this regard, resulting in unpredictable

control trims prior to take-off. Of course, the trim tabs can be

offset from centre to compensate for the errors. However, this

is difficult to do until the Hoverfly is in the air, and take-off is

difficult if the trims are not set fairly accurately beforehand. If

you have an old or unusual transmitter, we strongly suggest the

purchase of abasic type from our Standard list. Many dealers

will supply one separately, and they are inexpensive. It's well

worth it!

You are now ready to try out your Hoverfly for the first

time. To do so safely, please follow the commissioning

procedure in Section 9.

ii) Pick up the Hoverfly, holding it by the green rotor hub disc,

just below the central dome (Photo 1, Page 3). Your grip

should feel firm but comfortable. Ensure that nothing lies in the

path of the propellers, and be prepared for them to start up

suddenly.

iii) Switch on the mains. The gyro will now automatically

calibrate itself. The process takes about 3seconds, and during

this period the Hoverfly should not be moved. In normal use

this is easy, since it will generally be standing on the floor, but

right now it is held in the hand. Therefore, try to keep still just

after switching on the power! The gyro can always be reset by

switching off the power momentarily.

iv) At power-up, the red light should illuminate on the ECP,

followed by the green light after about 2seconds. The Hoverfly

may give amomentary twitch, but if it does more than this,

then something is wrong. For example, the collective channel

reverse switch could be set the wrong way, in which case the

Hoverfly would start at full power! This is the reason for

caution the first time it is turned on. If the motors do start up,

switch off the power again and check your set-ups carefully.

NOTE:When switching off the Hoverfly, ALWAYS turn off the

ECP power before the transmitter. Some transmitters, espe-

cially older types, generate arandom signal during turn-off.

This signal can make the Hoverfly start up momentarily if its

power supply is still connected, possibly causing damage.

v) If all seems to be well, it is time to try out the controls a

little. While still holding the Hoverfly, slowly advance the

collective stick. The main propellers should start to spin, and

the tail rotor may also turn. Adjust the rudder trim tab (below

the left joystick) to stop the tail rotor for the moment. DO NOT

ALLOW THE TAIL ROTOR TO TURN FAST FOR MORE

THAN AFEW SECONDS OR MOTOR DAMAGE MAY

RESULT. Now keep advancing the collective stick, and notice

how the propellers speed up. As they get faster, you will begin

to feel their thrust. Advance the collective all the way, listening

to the sound created at different settings. You should not,

however, let the motors run at full power for longer than about

15 seconds.

vi) Back off the collective until the motors are running slowly.

Hold the Hoverfly horizontally, so that the fuselage is free to

steer below the rotor. Take care not to grip the black dome, as

this is not part of the rotor, and will move with the fuselage.

Now move the rudder trim tab to the left acouple of clicks, so

that the tail rotor turns slowly. It should be turning counter-

clockwise when viewed from the left of the aircraft, and will

now be roughly trimmed for flight.

vii) Now try out the rudder control. Move the rudder stick

slowly to the left. The tail rotor will speed up, and the Hoverfly

will start to steer to the left. If you push the stick further to the

left, the rate of steer will increase, all the way to arapid

pirouette. Now centre the stick again. Pushing the stick to the

right will have asimilar effect, except that the tail rotor will

reverse direction, steering the Hoverfly to the right.

viii) Try out the gyro now to see how it works. With the main

motors running slowly, gently push the tail boom with one

finger, so as the steer the Hoverfly to the right. The gyro will

respond, speeding up the tail rotor in an attempt to prevent the

aircraft from turning. Pushing the tail the other way will have a

similar effect. Push it alittle harder, and you will notice quite a

firm effort against you. This is how the gyro prevents random

tail movements during flight. The aircraft will tend to remain

pointing in one direction, except when steered by apilot

joystick command.

NOTE: Because the gyro is sensitive, it will detect airframe

shake while the Hoverfly is revved-up on the ground. The

resulting signals may cause the tail rotor to jitter and stop

intermittently before take-off. This is normal.

ix) Bring the collective back to zero. All the propellers should

stop, and the gyro will stop responding. Stand the Hoverfly on

the floor in front of you. Advance the collective stick just a

little, until the propellers start to rotate. Move it forwards a

couple more clicks, and the rotor should start to revolve. Do not

advance the collective any further at the moment. The rotor

should turn easily, and freewheel alittle after you shut off the

motors. Now try moving the rudder stick while the Hoverfly is

standing on the ground, main motors running slowly. Be careful

not to change the collective setting as you move the stick from

side to side. You will notice that avery small amount of stick

movement causes the tail rotor to run at full speed. This is

because the stick movement acts as ademand signal,arequest

to the gyro to make the aircraft steer at the selected rate. The

gyro then attempts to obey, by driving the tail rotor progres-

sively harder until it senses that the requested rate of steer has

been reached. Because the aircraft is standing on the ground, it

cannot move, and hence the gyro tries its best without success!

x) Bring the collective back to zero again. Now pick up the

Hoverfly from behind, gripping it by the sides of the black

plastic mainframe, immediately above the undercarriage, but

below the tail (Photo 2, Page 3). DO NOT try to hold it by the

undercarriage itself. Check that the rotor is free to revolve, and

that nothing lies in the path of the propellers or tail rotor, then

bring up the collective to just above halfway. This is roughly

the hover position. When the rotor gets up to speed, which

takes about five seconds, you can try out the cyclic (aileron and

elevator) controls. These are operated by the right hand joystick

(Mode 2). Try pushing this stick in different directions. You

should notice the Hoverfly trying to tilt as the cyclic joystick is

moved off-centre. At the same time, you will hear an undulat-

ing sound from the motors, as the propellers change speed. It is

by changing the propeller speeds at different positions around

the rotor disc that the Hoverfly creates pitch and roll forces.

Once you have familiarised yourself with this control, reduce

the collective to zero again, and switch everything off.

NOTE: To compensate for the effect of gyroscopic precession

during flight, the cyclic controls act 90 degrees counter-

clockwise in relation to control stick movements. While the

helicopter is resting on the ground or held in the hand, it will

try to roll to the left when the control stick is pushed forwards,

or pitch forwards when the stick is pushed to the right, etc.

This is deceiving when trying to test the controls after set-up,

since it appears that the elevator and aileron channels are

mixed up. THIS IS NOT AMISTAKE, and the controls will

operate correctly as soon as the helicopter leaves the ground.

You are now almost ready to attempt your first flight.

However, in accordance with good flying practice, it is

important to carry out afew pre-flight checks (Section 10).

These should be done before every flight.

Trainer Undercarriage

To aid the stability at take-off and landing two black tubes are

supplied for forming awide undercarriage.

Pass one tube through the hole in the other to form across.

Attach this to the standard skids using

narrow strips of adhesive tape. Excess

from the decal stripes is ideal for this.

The easiest way to attach the training

undercarriage is to stand the Hoverfly on

it, and then tape the skids down. The

tape doesn't have to wrap all the way

round. This is easier than trying to do it

with the Hoverfly upside down. It will

not affect flight if the training undercar-

riage isn't perfectly positioned.

10. PRE-FLIGHT CHECKS

Before any flight, you should do the following:

a) Check that canopy, undercarriage and tailboom are all seated

securely in place, and that the tailfin is vertical. The boom can

be gently twisted to correct the latter.

b) Check that the Hoverfly stands up straight on the ground. If

not, gently adjust the undercarriage. If the aircraft stands

crooked, it will tend to topple over during take-off. Check that

the elevator and aileron trim tabs are centred.

c) Check that the collective stick is set to zero, then turn on the

transmitter, then the power. Allow 3seconds for the gyro to

auto-calibrate. DO NOT MOVE THE HOVERFLY DURING

THIS TIME. Now bring up the collective slightly, check that all

the motors run, and that the rotor revolves freely. The tail rotor

should turn gently, in an anticlockwise direction when viewed

from the left of the aircraft. If it is turning too fast, or the wrong

way, adjust the rudder trim tab on the transmitter to correct it.

The trim tab may have to be alittle off-centre. Now move the

rudder stick to ensure that the tail rotor responds correctly.

In addition, after maintenance, acrash or aheavy landing, do

the following:

d) Inspect the main motors to ensure they are properly seated in

their plastic brackets.

e) Check that the rotor is seated on the main shaft properly. If it

has lifted, take care not to damage the brushes when re-fitting

it. See Section 14B for help with this.

f) Check that the command line (inside the body) is securely

plugged in.

g) Check that the tail rotor retainer boss (the small plastic plug

that holds the tail rotor onto the drive pulley) is pushed fully

home. This occasionally comes loose in acrash, preventing the

tail rotor from being driven properly.

11. YOUR FIRST FLIGHT

If you are abeginner, we strongly recommend that you read the

whole of this section before actually flying. If you are an

experienced pilot, please read through the next three para-

graphs, which outline take-off technique for the Hoverfly.

For your first flights, choose aroom with as much unobstructed

space as possible. Do not attempt to fly outdoors. Place the

Hoverfly on the floor in the centre of the available flying area,

and facing away from you. Carry out the pre-flight checks

(Section 10) if you have not already done so. Position yourself

just behind the ECP and make yourself comfortable. After a

final check to ensure the command line will not snag on the

undercarriage or foul the tail, advance the collective about one

quarter. Wait while the rotor gets up speed, then continue to

advance the collective slowly, until you notice the Hoverfly

becoming light on its skids, and beginning to shake slightly. It

is now ready for take-off. Notice the collective setting, which

will probably be about halfway up. Note too the distinctive

sound of the motors at this point. Always remember to allow

time for the rotor to speed up when preparing for take-off.

THIS IS VITAL. The Hoverfly will blast off instantly if you

advance the collective far enough, but it will be unstable and

impossible to control until the rotor is up to speed.

If the Hoverfly topples over during the revving-up process, it is

asign that something is not quite adjusted perfectly for

take-off. Shut off the collective immediately, and look for the

problem. The ECP may be incorrectly trimmed; see Section 8,

Setting Control Trims for help with this. Also check that the

cyclic trim tabs on the transmitter are centred. Toppling will

also be caused if the Hoverfly is standing slightly crooked on

its skids. It is important to correct this, by adjusting the seating

of the undercarriage in the mainframe. Compressing the

undercarriage by pushing the helicopter against the floor will

often correct slight crookedness. Any tendency to topple will

prevent avertical take-off, probably causing anew pilot to

crash. DO NOT ATTEMPT TO TAKE OFF UNTIL THE

HOVERFLY IS REVVED UP TO SPEED ON THE

GROUND. The training undercarriage greatly reduces toppling

before take-off, and we strongly advise beginners to use it (see

Section 9for fitting instructions).

When revved-up and ready, advance the collective smartly to

achieve adecisive lift-off. With most transmitters, the Hoverfly

will leave the ground when the collective is just above the

central position. It will be tempting to linger at this point,

trying to hover an inch off the floor so as to prevent damage if

h) Hold the Hoverfly by the rotor hub, and advance the

collective alittle. Move the rudder stick, and check that the

aircraft steers in the correct direction. Incorrect steering

direction can be caused by incorrect belt fitting, or by

plugging in the tail motor electrical connector the wrong way

round. Arapid pirouette will result, because the gyro

response will reinforce rather than counteract tail move-

ments. It is important to find out about this before attempt-

ing to fly!

Tip: Beginners frequently crash. To facilitate frequent pre-

flight checks you may prefer to fly without the canopy fitted.

This is satisfactory if the tailboom is pushed 25mm forward in

its grommets to correct the balance of the Hoverfly. (Remove

the tailboom completely from the chassis before attempting to

move the grommets.)

you crash. Even experienced helicopter pilots do this! Unfortu-

nately, because the Hoverfly is so small, it is much harder to

control when this low, because of ground effect. It will tend to

skitter across the floor at high speed, until it bumps into

something. Be bolder, and give the collective aburst at take-off

to get the aircraft into the air quickly, to aheight of at least 12

inches. Control will then be alot easier. Provided that the

Hoverfly was up to speed without toppling over just prior to

take-off, it will leave the ground roughly vertically without the

use of any controls other than the collective. We strongly

recommend using this method to get into the air initially,

especially if you are anew pilot. Be ready to reduce the

collective almost immediately to prevent the Hoverfly hitting

the ceiling! Learning how to take off, reach asafe height and

then maintain it requires practice. Fortunately, the Hoverfly is

robust, and will withstand alot of bumping about.

Once in the air, it will immediately become apparent that the

Hoverfly will not stay there by itself. In addition to controlling

the height, you must learn how to use the rudder control to keep

it pointing in the direction you want, which will generally be

away from you. At the same time, you also have to learn to use

the all-important cyclic controls, which allow you to guide the

aircraft in the air or to keep it hovering in one place. Moving

the cyclic joystick will cause the Hoverfly to tilt in the direction

of stick movement, which in turn will cause it to accelerate in

that direction. To keep it hovering, you must learn to use this

joystick to compensate for the aircraft's random movements. It

is alittle like balancing abroom handle on your hand, though

somewhat harder to learn. The most common problem is one of

too much control, applied too late. This is followed by

over-compensation, and so on, which results in afurious

oscillation ending in acrash. It is important to learn to apply

small corrective control inputs in response to changes in aircraft

attitude.If you wait until the Hoverfly is actually moving before

applying correction, it will be too late.

If the Hoverfly is about to crash, it will often minimise damage

if you quickly shut off the collective and let the aircraft fall to

the floor. However, this reaction does tend to become in-

grained, and can be adifficult habit to break later on, causing

crashes in situations you would have been able to recover from.

When you do crash, check the Hoverfly over carefully (Section

10), then place it back in the middle of your flying area

before trying again.

The cyclic controls operate in relation to the aircraft itself. This

means that the aircraft will tilt towards its left when the cyclic

joystick is pushed to the left, etc. This gets very confusing when

the Hoverfly is facing you, or nose-in. This is why it is

important to learn to keep the aircraft pointing away from you

as early as possible. Pilots usually learn to fly in this orientation

first, before attempting nose-in flight.

Learning to fly will be much easier at the start if you can have

an experienced pilot help you. In particular, your helper will be

able to trim the Hoverfly accurately, so that the controls are all

truly at neutral when the joysticks are centred. The set-up

procedure trims the aircraft well enough to fly, but it is only

approximate. Awell-trimmed aircraft is easier to learn on.

Now practice, practice, and practice. Have fun, and Good Luck!

Note: Balance the rotor for smoother flight -see Section 14E.

Care of the command line -Section 14K, and tail maintenance

-Section 14F.

12. HELICOPTER PRINCIPLES

Conventional helicopters generate lift by means of the rapidly

moving rotor blades. Ahelicopter can have any number of

blades from two upwards, which collectively form the rotor.

The blades are shaped as aerofoils, and give the machine its

name; 'helico', meaning rotary, and 'pter', meaning wing. The

blades are set at an angle to the horizontal, so that they create

upward thrust as they turn, like agiant propeller. The angle of

inclination of the blades is referred to as their pitch,and can be

changed by the pilot using the helicopter's flight controls.

Overall lift is controlled by changing the pitch of all the blades

simultaneously. This is referred to as collective control,and

allows the pilot to cause the aircraft to climb or descend. To

maintain asteady altitude, the pilot must set the blades so that

the lift they provide exactly matches the helicopter's weight.

Directional control is achieved by varying the pitch of each

blade as it travels around its circular path, so that more lift is

provided on one half of the rotor disc than on the other. This is

referred to as cyclic control,and allows the pilot to tilt the

aircraft in any desired direction. For example, in order to make

the helicopter's nose drop (as if to dive), the pitch of each blade

is reduced as it enters the front semicircle, and increased as it

enters the rear semicircle. Less lift is then generated at the

front than at the rear, causing an imbalance which tilts the

whole aircraft. This in turn causes the helicopter to move

forwards, because the inclined rotor now provides some thrust

in this direction, rather than pulling straight upwards as it did

when it was spinning horizontally. This is how ahelicopter

achieves forward flight. The controls of ahelicopter allow the

pilot to tilt the aircraft from side to side (roll)as well as from

front to back (pitch,not to be confused with blade pitch!), and

any combination of the two, giving total freedom of movement.

Constant adjustment of these controls allows the pilot to keep

the machine exactly horizontal, and thus to hover. The

mechanism that achieves these control functions is complex,

and involves numerous mechanical linkages and push-rods, as

well as aspecial tiltable bearing called the swash-plate. In the

case of models, servos are needed in addition, to provide

physical actuation of the control mechanisms.

It is important to realise that ahelicopter does not hover or fly

by itself, but requires continuous fine adjustment of the

controls to maintain stability in the air. The skill required to do

this has to be learned, and is fundamental to helicopter flying.

However, ahelicopter derives agood deal of stability from the

rotating blades, which act as alarge gyroscope. This slows

down its rate of response to aspeed at which ahuman pilot can

control it, with practice!

The rotor of ahelicopter is generally driven by an engine

mounted in the fuselage, by means of alarge central drive-

shaft. In order to make the rotor turn, the engine has to push

against its mountings. This means that the engine is actually

trying to turn the helicopter fuselage just as hard as it is turning

the rotor itself. This unwanted turning force is referred to as a

torque reaction.In order to prevent the fuselage from

spinning, ahelicopter is fitted with atail rotor,which is

simply apropeller mounted sideways on the tip of the tail,

which pulls against the turning force from the engine. The tail

rotor's thrust can be changed, by altering the pitch of its blades.

This allows the pilot to steer the aircraft in the horizontal

plane, an action referred to as yaw.The control has the same

effect as aship's rudder, except that it works even while the

aircraft is stationary in the air.

Learning to use this control to keep the helicopter pointing in a

desired direction is afurther challenge for anew pilot. It has to

be done whilst at the same time keeping control over the other

axes of movement, which requires great concentration for a

beginner. Because the pilot of amodel is not actually inside the

aircraft, confusion tends to result when the machine is pointing

towards him/her. The aircraft's left hand side becomes the

pilot's right hand side, and vice versa. The pilot has to be

constantly aware of this in order to remain in control.

13. OVERVIEW OF THE HOVERFLY

The Hoverfly uses aradically new approach to generate lift and

control, to achieve aflight performance which closely resem-

bles real helicopters and conventional radio controlled models.

It is very lightweight, and employs an extremely slow rotor

speed, making it comparatively safe, and ideal for indoor

operation.

Unlike aconventional helicopter, the Hoverfly uses small

rotor-tip propellers to generate its lift. Each propeller is driven

by aseparate motor, and the main rotor turns only for the sake

of stability, driven by the propellers. This approach has a

number of advantages over conventional designs:

1) The propeller speeds can respond very rapidly to changes in

the electrical supply. This allows cyclic control to be provided

by changing the propeller speeds at the appropriate moments

during each revolution of the main rotor. This is apurely

electrical function, not requiring any mechanics; the need for a

swash plate and servos is entirely eliminated. The result is an

extremely small, lightweight and mechanically simple aircraft.

2) Alarge proportion of the aircraft mass is in the 3motors,

mounted at the rotor tips. This large rotating mass makes the

aircraft very stable, even at low rotor speeds. The stability

mimics much larger models effectively, while the low rotor

speed makes the model safe to operate indoors, and gives a

realistic 'scale' appearance in flight.

3) The drive that turns the main rotor is provided by the tip

mounted propellers, rather than from within the fuselage. There

is consequently no torque reaction created, which allows the

tail rotor to be very simple and low-powered. The tail rotor

provided on the Hoverfly is afixed-pitch propeller and is

needed only for yaw control (steering). It turns in either

direction, to allow for both directions of yaw.

14. MAINTENANCE

Numbers in square brackets refer to parts in Fig. 18-1.

A. DISASSEMBLY

1. Pull off the plastic dome [13] from the rotor shaft.

2. Slide the rotor re-

taining spring [14] off

the rotor shaft. This

may be quite tight,

but it can be levered

up from the rotor hub

by straddling the shaft

just below it with the

blades of asmall pair

of scissors (Photo 3).

Twisting the spring

against the direction of the coils will also loosen it during

withdrawal. Be careful not to lose it!

3. Carefully lift off the rotor.

4. The bottom lip of

the canopy [12] is

pulled in at the front

by a plastic strap

(Photo 4). This pre-

vents the canopy from

lifting off at the front.

To remove the

canopy, pull it gently

off its foam mounting

at the top of the main-

frame. Lift it over the shaft, and slide it forwards to clear the

yaw motor.

5. Remove the undercarriage [23] by pulling it downwards out

of the mainframe [11]. The command line passes through the

undercarriage, so it has to be fed along to the end in order to

free it.

6. Unplug the lead to

the yaw motor [20] (it

plugs in at the top of

the mainframe, Photo

5).

7. Push the boom [25]

downwards until the

two mounting grom-

mets [24] are released

from the mainframe

clips (Photo 6). With-

draw the boom care-

fully, guiding the yaw

motor through the

mainframe.

8. Unplug the com-

mand line from the

mainframe. To do

this, carefully prise

the three-limbed elec-

trical connector [16]

off the pins under the

main shaft (Photo 7).

Prise up the limbs

progressively, so as

not to bend the pins.

DO NOT pull on the wire or plug stem [17].

B. REASSEMBLY

This is basically steps 1to 8above, in reverse order. Pay

attention to the following:-

Step 8. One limb of

the command line

plug [16] has aflat

end. This carries a

white spot (Photo 8),

which aligns to the

white spot on the

alignment lug at the

edge of the socket.

Step 7. Before fitting the boom assembly, ensure the grommets

[24] are correctly positioned. They should lie just outside the

white rings on the boom. The command line should pass on the

right hand side of the boom. Ensure the fin [2] and yaw motor

[20] are upright (motor on top of the boom, tail propeller [6] on

the left).

Step 6.The yaw motor connector plug carries awhite spot,

which aligns to the white spot on the socket.

Step 5. When fitting the undercarriage [23], pass the command

line through the loop between the crosswires and the right hand

skid.

Step 4.When fitting the canopy [12], engage the front first,

then ease the top over the shaft and onto the mainframe foam

mounting.

Step 3. Fitting the ro-

tor requires some care

to ensure that the car-

bon brushes do not get

damaged. Slide the ro-

tor onto the shaft, ma-

noeuvring it so that

the three brushes lie

against the shaft sym-

metrically (Photo 9).

Ensure that the upper

brush is on the correct side of the shaft as the rotor is lowered.

Do not try to force the rotor down until the three brushes have

been lifted onto the cylindrical surface of the commutator. Use

asmall hook (the

head of apin will do)

to manoeuvre each

brush into place.

Take care not to

over-bend the brush

wires. When all the

brushes are resting

on the commutator

(Photo 10), allow the

rotor to seat fully.

Step 2.Lift the up-

per brush onto the

retaining spring [14]

as it is fitted (Photo

11). Do not push the

retaining spring too

hard onto the top of

the rotor. The rotor

must turn freely. We

recommend about

0.25mm clearance.

C. MAIN MOTOR REPLACEMENT

Do not attempt to do this unless you are confident of your

soldering ability.

1. Unsolder the two wires from the motor terminals using an

iron with asmall tip.

2. Pull off the push-fit propeller. (See Dbelow)

3. Lift the top of the plastic bracket off the upper motor boss,

and ease it over the shaft. Gently prise the base of the motor

free from the bracket, and withdraw it upwards.

4. Fitting the motor is the reverse of the above. The outer

plastic retaining band can be bent out of the way during motor

fitting, then replaced squarely round the side of the motor

afterwards. Ensure that the electrical terminal marked

MABUCHI is located towards the centre of the rotor. The blue

wire connects to this terminal. Carefully re-solder both wires

and dress them against the motor bracket. Take care to ensure

that the gold wire cannot chafe against the innermost motor

terminal, since this will eventually cause an electrical short

circuit.

D. PROPELLER REMOVAL AND RE-FITTING

The propellers are atight push-fit onto the motor shafts. To

remove, the motor should be grasped at the sides between

thumb and forefin-

gers, so as to clamp

the armature, pre-

venting the motor

from turning (Photo

12). The propeller

can then be twisted

back and forth whilst

pulling it in order to

remove it. Re-fitting

is done in much the

same way, taking care to offer the propeller up to the motor

shaft as squarely as possible. Take extra care when fitting a

new propeller, to hold the motor armature very firmly,

otherwise the downward force of fitting can dislodge the lower

motor bearing, damaging the motor's plastic back-plate.

Propellers are supplied as matched sets of three, because it is

important that they give equal thrust. The packaging carries a

single digit thrust number, and all three propellers fitted to the

Hoverfly should bear the same number, to prevent flight

wobble.

WARNING: THE MOTORS MAY BE HOT AFTER

RUNNING FOR SOME TIME.

E. ROTOR BALANCING

Although the Hoverfly comes ready to fly, flight performance

can sometimes be improved by fine balancing of the rotor. This

will reduce the amount of aircraft 'wobble' experienced during

flight, especially at hover. Atruly well balanced Hoverfly will

fly silky smooth, and is adelight to watch. Wobble caused by

crash damage can also be greatly reduced by balancing the

rotor. The procedure is straightforward, involving simple trial

and error. One of the great features of the Hoverfly is its ability

to fly when badly out of balance and trim; this allows for safe

experimentation.

The rotor will be balanced by adding small pieces of 'Blu Tac'

to the ends of the arms, on atrial and error basis. The correct

solution is usually one of two possibilities:

i) If one of the arms is abit light, adding weight to it will fix

the wobble.

ii) If one of the arms is abit heavy, adding weight to the other

two arms will fix the wobble.

Some points to note:

a) You will never need to add weight to all three arms.

b) When two weights are needed, they can usually be roughly

equal.

c) The level of precision required is not very great. It really isn't

hard to make abig difference!

d) Wobble is actually caused by several interrelated factors,

which create acomposite effect which is addressed by adding

weights. Dynamic imbalance is one of them. However, wobble

will also be caused by slight inaccuracies in motor alignment

(especially radial slant), distorted rotor geometry (don't let the

rotor get wet), and chipped propellers. Awobble sometimes

occurs after arebuild, due to imperfect carbon brush contact.

This will generally cure itself after aminute or two in the air.

e) If you are abeginner, or if you fly wild and crash alot, it

really isn't worth being too fussy. You could buy asecond rotor,

for special occasions!

4. The belt should be carefully checked for damage and wear. If

it is not in perfect condition, it should be renewed. Re-insert

the belt (see Gbelow).

5. Re-assemble the Hoverfly, and test the tail before flying.

Especially, ensure that the direction is correct. (See Fig 14-1)

Note: Never run the tail motor without the belt and

propeller fitted. Over-revving damage may result.

Tip: After a while, especially in warm conditions, the tailboom

may droop. This can be corrected by twisting it through 180

degrees. Having done so, turn the end fittings back again, so

that they finish the right way up. Take care to rotate the ends

the same way, to avoid twisting the belt.

G. BELT INSERTION

1. Attach the tailboom lightly to atabletop with tape (or get a

helper to hold it). The motor end should be on your left, and the

propeller uppermost.

2. Pass the special Belt Insertion Tool into the motor end of the

boom, in front of the motor pulley, hooked-end first and

uppermost (Fig 14-1). When it comes out of the other end,

position the hook just beyond the small pulley, as illustrated.

3. Now lay the belt in

the groove of the

large pulley, drawing

it away from you,

through the hook in

the tool (Photo 14).

Hold it loosely ex-

tended with your right

hand. With your left

hand, pull the belt

into the boom using

the tool, allowing the rubber to run around the small pulley on

the way. It will then take up its correct position quite naturally.

Keep slight tension on it all the time, letting go with your right

hand at the final moment, to allow the belt to drop fully into the

large pulley groove.

4. When the hook emerges from the left hand end, pull it just

beyond the motor, so that the two strands of rubber are drawn

The balancing procedure is as follows:

1. With apencil, number each of the motors for easy

identification.

2. Fly the Hoverfly, and note the amount of wobble present.

3. Roll out asmall

ball of 'Blu Tac', 5-6

mm in diameter.

Stick it to the outer

edge of motor 1

(Photo 13).

4. Fly the Hoverfly

again. Note if the

wobble has improved

or worsened.

5. If the wobble has worsened, try moving the 'Blu Tac' to

motor 2and try again, etc.

6. If adding weight to any one motor doesn't seem to work, then

try weighting pairs of motors in turn. This gives three more

possible solutions.

7. Once you have found the right motor(s), you can try different

amounts of weight. 5-6mm diameter is agood start, but do

experiment.

8. When you are happy with the balance, you can move the 'Blu

Tac’ to the inside edge of the motor (this will not change the

balance noticeably). The plastic bracket has aconvenient recess

under the rotor arm where it can be hidden.

F. TAIL MAINTENANCE

Although robust, the tail mechanism does require maintenance

in order to keep it working well. In-flight tail rotor failures will

often lead to acrash; therefore, we recommend the following

after every five hours flying time:

1. Remove the undercarriage [23], unplug the lead to the yaw

motor (Photo 5, Page 12, this can be reached with the canopy in

place, just!), and unclip the tailboom [25] from the mainframe

(Photo 6, Page 12). Remove it completely.

2. Using apointed tool, un-hook the belt [9] from the motor

pulley [21], and remove it from the other end.

3. Check that both rear pulleys [4, 8] turn freely. Lubricate each

pulley bearing sparingly,using apiece of thin wire dipped in

light vegetable oil to reach the running surface between each

pulley and the bracket [3]. Remove the tail propeller [6] by

prising out its retaining plug [7]. Apply asmall drop of oil next

to the top of the bearing pin [5] inside the propeller mounting

turret. Take great care not to let any oil get into the pulley

grooves, and carefully remove any that does. The large pulley

[4] and the pin on which it runs both eventually become worn,

resulting in noisy operation and reduced performance. If the

pulley can be wobbled on its pin, these parts should be

renewed (Section J). The yaw motor requires no maintenance,

and must not be oiled.

Fig 14-1

past the pulley side by side. Now lower the belt onto the edge

of the pulley, so that the strand furthest from you drops over the

rim and down into the groove. Finish wrapping the belt around

the pulley in an anticlockwise direction, using the hook to

manoeuvre it into place. The belt will now be aligned as in the

diagram.

Take care not to twist the belt while pulling it through the

tube.

Check that the direction of rotation is correct before flying.

See Fig 14-1; turning the motor pulley in direction Xshould

cause the tail pulley to rotate as Y.

H. TAIL PROPELLER REPLACEMENT

Carefully pull out the propeller retaining plug [7] to release the

propeller. Press this through the new propeller, and re-insert,

pushing it fully home.

I. TAILFIN REPLACEMENT

The fin may be removed by prising off its retaining bar [1].

J. TAIL PULLEY REMOVAL AND RE-FITTING

1. Each rear pulley [4, 8] is held in place by ashaft pin [5], on

which it runs. This pin can be seen on the small pulley, but is

hidden inside the larger pulley. The pins push-fit into the

bracket [3].

2. Remove either pulley by prising it carefully away from the

bracket.

3. To re-fit the small pulley, the pin should be pressed into the

bracket hole until its tip is flush with the other side. This is

easy if the bracket is held against aflat surface.

4. To re-fit the large pulley, the tail rotor must be removed to

gain access to the pin. The pin can be pushed with a

screwdriver or similar blunt tool. The pin should be pushed in

sufficiently to leave no more than 0.25mm clearance between

pulley and bracket. The belt insertion tool makes an ideal

spacer to get the clearance correct.

K. CARE OF THE COMMAND LINE

The command line is vital to the Hoverfly. It carries no less

than 9separate electrical signals, on 14 thin strands. It is quite

robust, but requires care in handling. Please note the following:

1. The two possible failures are broken strands, and short

circuits between strands. Both can be caused by careless use.

2. Kinks will weaken the wire. Be very careful to remove all

loops when unwinding it, before they get pulled tight. Run the

wire between thumb and forefingers to straighten it before

flying. After use, wind the line onto the spool provided, starting

from the Hoverfly end, so that twists can fall out. Alternatively,

make areally large spool (30cms or more), to keep twists to a

minimum.

3. Be careful to avoid letting the line drag over sharp metal

corners, such as electrical equipment cases. This can scrape the

insulation from the wires.

4. If the strands separate, twist them together again.

5. Take care to keep the command line from catching in the

propellers or rotor. If it gets wound around the rotor shaft,

switch off the power immediately.Remove the rotor if

necessary to untangle the strands from the brushgear.

6. Do not use the Hoverfly if the command line gets wet. Allow

it to dry thoroughly first.

7. If acommand line short circuit occurs, the ECP will usually

switch itself off for protection. To reset it, unplug the power

briefly.

L. OPENING AND CLOSING THE ECP CASE

1. The ECP case splits into atop and abottom section. To

separate, hold it by the lower half, and squeeze the sides firmly.

The top half will then lift off.

2. To close, offer up the top half squarely, and in line with the

bottom. Adjust the two LEDs slightly if necessary to ensure that

they engage with the holes in the top. Snap the two halves

together gently.

M. GYRO REMOVAL AND INSTALLATION

The gyro is the small electronic circuit board [10] located

within the mainframe. The circuit board carries asilver-

coloured oblong sensor, which engages in the rectangular

plastic frame that forms part of the command line connector

stem [17]. The gyro is connected to the command line by a

small black plug, which engages with pins on the circuit board.

The wiring is thin, and should therefore be treated gently.

Removal

1. Disconnect the Hoverfly from the ECP.

2. Remove the rotor and canopy (Section 14A, steps 1to 4).

3. Withdraw the gyro rearwards, by easing the silver sensor out

of the plastic frame which houses it. Asmall screwdriver can be

used to gently prise the sensor out. Take care when removing,

not to tug on the wiring.

4. Unplug the connector from the circuit board, to free the gyro.

Installation

1. With the rotor and

canopy removed as

above, plug the elec-

trical connector onto

the three pins on the

gyro circuit board

(Photo 15). The con-

nector carries awhite

spot on one side,

which must be ori-

ented towards the

edge of the circuit board. This faces the left of the aircraft when

the gyro is installed. Incorrect connection will not do any

damage, but the gyro won't work!

2. Press the silver

sensor into the rec-

tangular frame on the

command line stem,

offering it up from

the rear. The electri-

cal connector should

be at the bottom

(Photo 16). 16

15. FITTING THE WINDOW AND DECALS

1. To fit the window, firstly cut around the moulded outline to

remove the excess material.

2. Grooves on the canopy show how to align the window. Hold

it in place with apiece of the white tape provided, to create a

window frame effect. Aneat method is to run asingle piece of

tape down the centre, from top to bottom, overlapping onto the

canopy to hold the window on. The rear corners can be taped

down with transparent tape. Excess from the decal sheet is

ideal. The window does not need to be taped around the edge.

3. Stripes can be added to the canopy and tail as desired. The

tape provided will stretch to turn through tight curves, without

peeling off. The picture on the box suggests one possible

arrangement for the stripes.

4. The decals can be cut out and applied as desired. They peel

and stick, and do not come off easily.

NOTE: The canopy is most easily decorated by removing it.

To avoid the need to disassemble the Hoverfly for this purpose,

you may wish to purchase aspare canopy and decorate that,

especially if you are abeginner. The decorated canopy can be

substituted when you have learnt to fly.

16. TIPS AND TROUBLESHOOTING

16.1 In-flight wobble and rotor repair.

Section 14E. contains adetailed procedure for balancing the

rotor to reduce wobble, which works well in the majority of

cases, where the wobble is only cosmetic. If the wobble is bad

enough to make flight difficult, then there is probably some-

thing else wrong, such as afaulty motor. There are afew other

issues worth mentioning.

Firstly, it is important to realise that the propellers come as sets

of three, which have been closely matched for thrust. Although

moulded, the propellers do vary somewhat in pitch, due to

random cooling distortions. To achieve smooth flight, the three

propellers must provide equal thrust, and track well during

speed changes. Replacement propellers carry asingle digit

thrust number on their packaging, which allows them to be

mixed with other propellers bearing the same number. Adja-

cent numbered propellers will often mix OK too, but mixing

high and low numbered propellers will tend to cause flight

wobble. However, mixing thrust numbers can sometimes be

used as

ameans of curing awobble caused by some other fault, such as

adamaged rotor arm. It's worth experimenting.

Crashing can of course damage the rotor, causing wobbly flight

afterwards. Sometimes the rotor may look OK, but in fact, one

of the arms has been bent out of alignment in the crash.

Vertical slant on arotor arm, where it differs from the others,

will especially cause wobble. This can be seen if the rotor is

viewed side on whilst fitted to the fuselage. Each arm can be

rotated into view in turn, and acareful eye can spot any

difference in arm slant. Abent arm can often be straightened

again, by bending it from the root where it leaves the hub

moulding. The rotor arms are made from very elastic spruce,

and extreme care must therefore be taken, since the wood must

be forced close to breaking point in order to create apermanent

bend. The process will be easier if the outer plastic covering is

removed first, by slitting it lengthways with asharp knife. It

can be re-fitted afterwards.

Because of the importance of accurate rotor geometry, we

generally recommend replacing abroken rotor, rather than

attempting arepair. The bare frame is inexpensive, and can be

built up in about half an hour. However, with care, arepair can

be done. Arms tend to break close to the root, so that the

weight of splints etc. added to strengthen ajoint will not affect

balance very much. Counterweights can always be added,

anyway. It is important when repairing an arm, to get it exactly

straight so that the motor is equidistant from the others, and

lies in the correct plane. The forward slant of the motor should

be 5degrees (it should be tilted anticlockwise from the vertical

when viewed towards the centre of the rotor). The arm should,

of course, finish up the same length as the others. The plastic

covering can be left off the repaired arm if necessary, without

affecting flight performance significantly.

16.2 Adjusting tail performance.

The effectiveness of the tail rotor can be varied by altering the

pitch of its blades. This is easily done by adjusting the folds in

the plastic propeller, close to the centre. There is no need to

remove the propeller to do this, but it is worth making sure that

the retaining boss hasn't been loosened during the process.

Increasing the blade pitch makes the tail easier to handle,

because the gyro's effectiveness is increased. The tail can be

made very 'tight' indeed, giving rapid rates of yaw, with very

snappy, almost instant stopping. Too much pitch will cause the

tail to wag, because the gyro becomes unstable.

16.3 One of the motors won't run.

If one of the main motors won't run, then afault lies on the

rotor. Check the wiring, especially the soldered connections to

the motor terminals. Make sure that the gold wire is not

chafing against the inner motor terminal. This can lead to a

short circuit, causing the motor to stop running. The ECP will

usually shut down, too (disconnect the power briefly to reset

it). Also check that the rotor itself is properly seated on the

main shaft. It can occasionally get forced up during acrash.

The carbon brushes on the underside of the hub should rest on

the cylindrical surface of the commutator (Photo 10, Page 13).

Take care when re-fitting, to lift the brushes onto the

commutator surface before pushing the rotor down, otherwise

they will be damaged.

Make sure that the motor turns freely. Acrash will sometimes

dislodge the lower bearing, causing stiffness. It is also possible

for apropeller to get forced on hard enough to jam. Another

problem which occasionally arises after acrash is particularly

bizarre. The motor can pick up asmall fragment of metal from

somewhere, which sticks to one of the magnets. It may then get

trapped against the armature, jamming it. Turning the motor

backwards will bring the culprit into view, when it can be

removed with tweezers.

If each motor stops as it passes acertain place during

revolution, then the fault is electrical, and lies outside the rotor

itself. The most likely cause is aloose command line plug,

either in the Hoverfly, or at the ECP end. Abroken strand in

the command line can cause this too, as can afault in the ECP.

If you are unable to trace it, contact Snelflight, and we will be

happy to help.

16.4 The tail rotor runs fast all the time.

This problem can have avariety of causes. The first thing to

check is that the Hoverfly isn't moved during the 3second gyro

auto-calibration period immediately after power-up. During

this time, the gyro zeros itself. It is important that the aircraft

doesn't move during this period, otherwise the gyro will not

subsequently know what speed stopped is! This causes the gyro

to drive the tail rotor when the aircraft is actually stationary,

because it thinks that the helicopter is moving. To cure the

problem, simply disconnect the power momentarily, then let

the Hoverfly stand still for 3seconds after reconnection.

Having eliminated the gyro problem, the next thing to check is

the rudder trim setting. Due to the Yaw Rate Demand system,

the tail rotor is very sensitive to small movements of the rudder

stick. This makes it sensitive to trim offsets too, which can be

caused by slight zero errors in the transmitter or ECP,

electronic component tolerances, etc. Having set the ECP trim

according to the instructions in Section 8, it may be necessary

to offset the transmitter trim tab somewhat in order to bring the

tail rotor to the correct idle speed, which should be agentle

anticlockwise rotation, viewed from the left of the aircraft.

If the above methods fail, then the problem may be caused by

incorrect transmitter set-ups, such as Throttle to Rudder mixing

(Switch this off!) or incorrect channel patching, although

generally more than one problem would arise from this. A

broken or shorted command line strand can cause the tail rotor

to run continuously at full speed, as can plugging in the 3way

gyro connector the wrong way round (see Section 14M). Very

occasionally, one of the pins in the command line ECP plug can

become bent or broken, causing an electrical disconnection or

short circuit.

16.5 The Hoverfly blasts off at full power as soon as it is

switched on.

When switching on the power for the first time, or after

performing set-up changes, it is important to hold the Hoverfly,

grasping it by the rotor hub. This will prevent damage if it

should start up unexpectedly. Asafe commissioning procedure

is described in Section 9. Please do read this! The pre-flight

checks in Section 10 take seconds to perform, and are well

worth making routine.

The commonest causes of blasting off at power-up are:

i) Setting the transmitter to PCM mode instead of PPM. The

ECP cannot interpret PCM signals (there are several different

proprietary systems anyway), but will be fooled into starting

because asignal is present. When no signal at all is received,

the ECP shuts down. The transmitter MUST be set to PPM

mode.

ii) Incorrect throttle servo reverse switch setting (in the

transmitter). When the stick is set to zero, the power is really

on maximum. Refer to Sections 6and 7for the set-up

procedure.

iii) Incorrect connections in the ECP Patch Socket. For

example, the collective may be connected to the rudder stick,

which would cause the motors to start up at about half speed,

since the rudder stick rests at the centre position.

16.6 The Hoverfly topples over, or skitters off sideways

when Itry to take off.

To take off vertically, the Hoverfly must be trimmed properly

(Section 8), and it must be standing up straight on the ground

prior to lift-off (Section 11). The collective should then be

brought up gradually, in order to allow the rotor to come up to

speed. Just prior to leaving the ground, the Hoverfly will

become obviously light on its skids, and will start to shake. It is

now that it is most prone to toppling over, but if it doesn't, then

it is definitely cleared for take-off! Provided that the ECP has

been trimmed correctly, toppling during the revving-up process

is usually due to crooked standing. Press the Hoverfly down on

its skids firmly, in order to compress the undercarriage. This

often corrects crookedness. If not, then it will be necessary to

adjust the bends in the undercarriage wires where they exit the

mainframe. The skids should be horizontal when viewed from

the side, and level with each other when viewed from the front

(or rear). Toppling can also be caused by an out-of-balance

rotor, or by trying to rev-up too quickly. The training undercar-

riage is abig help.

Once revved up and ready, increasing the collective alittle

further will result in aclean take-off. Give enough of apower

burst to get the Hoverfly up to aheight of 12 inches or so, to

clear ground effect. Get it up in the air quickly, so that it has no

opportunity to slide along the floor. Leave the other controls

alone during the actual lift-off. What happens next is up to the

pilot, but the Hoverfly will take-off on its own. Do read Section

11, which describes take-off in more detail.

16.7 When Itry out the controls, the Aileron and Elevator

functions seem to be mixed up.

This is due to the effect of gyroscopic precession. In order to

compensate for this in flight, the controls act 90 degrees

anticlockwise relative to the direction of cyclic joystick move-

ment. This is deceiving while the aircraft is standing on the

ground or held in the hand. If the joystick is pushed forwards,

the Hoverfly will roll to the left, and if the stick is pushed to

the left, the Hoverfly will pitch backwards, etc. This is

perfectly correct, normal operation! The effect is very pro-

nounced on the Hoverfly because the rotor does not tilt in

relation to the fuselage, as it does on many helicopters, and

because alarge proportion of the aircraft's mass is in the rotor

(well over 50%). The controls will act normally as soon as the

Hoverfly leaves the ground, even while in ground effect. If the

cyclic controls are operated whilst the Hoverfly is held by the

rotor, so that the latter is not turning, then the response from

the aircraft will bear no relation to joystick movements at all.

16.8 How can Ikeep the command line strands from

separating?

An excellent way to keep the command line in good shape is to

twist it up occasionally using an electric drill. You will need a

variable speed type, with ahalf-inch chuck. The command line

ECP plug will fit into this; clamp it very gently. There is no

need to disconnect the Hoverfly end. Stretch the wire out

straight, and make absolutely certain that there are no kinks in

it. Either have ahelper hold the Hoverfly, or find away to

wedge it on its side. This will be easier if you remove the rotor.

Whatever you do, make sure it really can't move. Tape it to

something if necessary.

Now go to the other end and hold the drill so that the command

line is slightly slack (say 3inches of droop). Start it running

17. SPECIFICATIONS

Aircraft weight 68 grams

Rotor diameter 284mm measured to motor shafts.

Rotor speed at hover 250 rpm. *

Tip propeller speed at hover 22,000 rpm. *

Power consumption at hover 25W

ECP supply voltage 34V

Signalling system 4channel PPM (Pulse Position Modulation), 1.52ms centre

*These ratings are approximate.

slowly, in the normal clockwise direction, and gradually build

up abit of speed. Put in about 100 turns of twist. This will take

three or four seconds at medium speed. DO NOT LET THE

LINE GO SLACK! If you do, ahopeless tangle will result.

When you have finished, remove the plug from the chuck

whilst keeping the wire tight, then allow the plug to spin in

your hand so that excess twists can unwind. Only after this

should you let the line go slack. If you don't let the excess

twists unwind, the wire will double twist when it slackens,

creating atangle.

The command line will behave slightly differently just after

twisting. It will seem slightly springier, and less inclined to

kink. This effect will gradually fade as the twists loosen up, but

you can control the wire's character somewhat by varying the

number of twists you put in. It's one more thing to play with!

Fig 18-1

ROTOR

1001 Rotor, complete with motors and propellers

1002 Rotor frame, bare

1002A Rotor, less motors /brushes

4003 Hub PCB, pinned

7201(4) Rotor brushes (set of 4)

5024(3) Propeller (matched set of 3)

SH030 Main motor

TAIL BOOM ASSEMBLY

1005 Complete assy, with yaw motor

3004 20 Yaw motor, with plug

5010 22 Motor bracket

5011 3 Tail bracket

5012 1 Fin retainer

5013 8 Idler pulley

5014 21 Motor pulley

5015 4 Tail pulley

5016(2) 5Pulley shaft pins (2)

5018 7 Tail rotor retainer

5019(2) 24 Grommets (2)

5101 2 Tail fin

5102 6 Tail rotor

8202 9 Drive belt

BOOM 25 Boom tube, with location marks

CONTROL UNIT

1003 Electrocyclic Control Processor

7302(4) Patch link (set of 4)

Part No. Description

OTHER PARTS

2101 23 Undercarriage

3001 26 Helicopter command line, 3.5 mtr

3001-6 Helicopter command line, 6mtr

3002 Signal lead (JR /Sanwa, 3.5mm jack)

3003 Signal lead (Futaba /Hitec, 6way DIN)

3005 Signal lead (Sanwa, 6way DIN)

3007 Signal lead (Sanwa RD6000, 5way DIN)

5003 13 Dome cap

1004 11/15 Mainframe with commutator

5125 12 Canopy (with brace)

5128 Window

6303(2) 14 Spring collar (rotor retainer) (2)

DECALKIT Red/white stripes and decals sheet

G100 10 Gyro

PSU-UNI Power supply

3008 Mains lead, UK

3009 Mains lead, USA

3010 Mains lead, Europe

ACCESSORIES

5104 Belt Insertion Tool

8205 Command line reel

8001 Instructions and Maintenance Manual

CASE1 Carrying case, lined

Part No. Description

18. SPARES

For spares, contact your supplier, or in

case of difficulty apply to:-

Snelflight Ltd

Churchill House

57 Jubilee Road

Waterlooville

Hants

PO7 7RF

Tel:- 023 92 258999

Fax:- 023 92 251333

E-mail:-

[email protected]

Fig. 18-1 Fig. 18-1

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