Assembling The Model - iKarus PRO Piccolo Bauanleitung

Vorschau ausblenden

Inhaltsverzeichnis

Verfügbare Sprachen

Idle-up, throttle curve: the main rotor must first be

accelerated to its working speed. Once the model is

flying, more blade pitch (collective pitch) is mixed in

when the throttle is opened to give more power. The

principle works well up to a point, except that rotor speed

declines when you reduce collective pitch. If increased

power is suddenly required, there may be an unacceptable

delay before the motor develops the torque required. This

can be prevented by defining a certain basic value below

which motor speed never falls - a solution known as "idle-

up". This means that the motor is always developing a

certain minimum level of torque, from which it can easily

develop the power levels required at any time. When the

system is properly set-up, you will detect no collapses in

rotor speed.

Setting-up: the following settings refer to a linear collective

pitch set-up, i.e. no alterations to the collective pitch curve

or collective pitch values. For aerobatic and inverted flight a

rotor speed ... //

How does a helicopter fly?

Helicopters generate the upthrust required to fly by means

of revolving wings: the rotor blades. The main rotor is driven

by a motor, and therefore also generates unwanted torque.

As a result the helicopter always tries to rotate around its

vertical (yaw) axis. The tail rotor counteracts this

(unwanted) rotation by producing thrust in the lateral

direction. The tail rotor's thrust can also be varied

intentionally in order to change the helicopter's heading.

We have therefore already met two functions required to

control the helicopter: climb and descent is controlled by

altering rotor thrust (collective pitch). Rotation around the

vertical axis is controlled via the thrust of the tail rotor, i.e.

by varying its rotational speed.

However, that is not enough; we must also be able to steer

the helicopter forwards and back (pitch-axis function) and to

both sides (roll function).

It is not possible to control these functions directly. Instead

we make a minor detour and engage the help of the Hiller

paddles. Their pitch angle is varied cyclically by the servos

via the swashplate, i.e. their pitch varies, but is always the

same at any particular position. This action tilts the

rotational plane of the Hiller paddles, and thereby the main

rotor; effectively the main rotor remains plano-parallel to the

swashplate. Thus if the swashplate is inclined forward, the

plane of the Hiller paddles also tilts forward, and with it the

main rotor plane. The net result is that the thrust of the rotor

is directed slightly forward instead of vertically, and our

helicopter responds by moving in the forward direction. An

analogous situation occurs when a "back cyclic" command

is given, or a roll command to either side.

We now have four direct control functions, and indeed we

need all of them because the helicopter is free to move in

these four ways, especially when in the hover:

- Linear movements: up / down, forward / back, sideways;

- Rotation, viz. rotation around the vertical axis.

We only have one basic aid to control, and that is a gyro,

which stabilises the helicopter's movement around its

vertical axis. The gyro detects unwanted motion around this

axis and alters the thrust of the tail rotor to counteract it.

The result is that the helicopter does not carry out any

sudden movements around the yaw axis.

However, we are getting ahead of ourselves; before we can

fly the PRO-Piccolo we have to assemble the model. Kindly

bear in mind that this helicopter is and must be a

lightweight, so be sparing with the adhesive, and -

especially - with adhesive tape.

Remember that every gramme of excess weight costs

around one second of air time, so please take the trouble to

save weight wherever humanly possible, and be sure to

install truly lightweight components such as our Piccoboard.