In its basic form this is a four channel unit (nine channels are available, but only four are controlled, via the sticks) with a bank of 12 switches in the lower left corner of the case. The first eight of these cater for servo reversing on channels 1 - 8, while switches 9 - 11 exchange various stick functions, as below, and switch 12 chooses either PCM or PPM operation.

Switch 9. This is associated with the action of the "combi-switch", a device commonly found on equipment of continental manufacture but virtually unknown elsewhere. What it does is to couple the ailerons and rudder. The degree of coupling is either fixed or variable depending on which of the various "soft modules" is in use. Returning to switch 9, this decides which channel is the master and which is the slave. Or, to put it another way, whether rudder is coupled to aileron or aileron to rudder.

Switch 10 is used to select whether the elevator is controlled from the left or right hand stick; the throttle then being controlled from the other stick. Very useful for those who fly "left-handed mode 2" or other less common control arrangements.

Switch 11 fulfils a similar function in that it selects whether the ailerons are controlled from the right or left hand stick.

This brings us to the previously mentioned "soft modules" without which the transmitter cannot work. To the right of the above switches is located a large socket which accommodates the various soft modules. For the basic transmitter so far described there are a range of modules prefixed by the letter "B". These range from a standard all-purpose type (B1) through types designed for gliders (B3), "V" tailed models (B5), deltas (B6), helicopters (B7[8]), models with flapperons (B9) and model boats (B10).

Below the switches are 4 adjusters which can serve many different purposes depending on which soft module is fitted. If the B1 module is fitted, for instance, they vary the throw of the four main control channels. By fitting four toggle switches to any of a number of possible locations on the top of the transmitter the action of these adjusters can be switched out. Hey presto! Instant rate switches! To describe the various combinations which can be obtained with just the "B" series of modules alone would take more space than we have available, but you get the idea.

There is one other feature of the basic transmitter located above the soft module socket. This is what is called the In/Out socket due to its being able to perform a wide variety of tasks:-

1) A charge socket for charging the transmitter battery(s).

2) For the use of a buddy box teacher/pupil system with the aid of another "ROYAL mc" transmitter. In this mode, the pupil transmitters reversing switches now select which individual channels shall be capable of being overridden by the teacher, while the teachers transmitter configures all the various controls as required. This offers many advantages over the usual system.

3) Fitting a closed loop lead for operating the receiver without transmitting an RF signal.

4) Connecting other "intelligent" auxiliary devices! This includes connecting to a computer for special programming or control.

The basic transmitter can be expanded by the fitting of a double slider control unit, an adjuster/electronics extension module and a reserve battery and battery change over switch. These are not mutually dependent and any or all of them may be fitted as required.

Double slider control unit. This extends the basic transmitter to a six channel unit by adding two slider controls between the main sticks

Adjuster/electronics extension module. This fits on the lower right of the transmitter case and adds another bank of 12 switches together with a further 14 adjusters. All of these can be configured to give many variations of control layout and control inter-relations by means of further soft modules. Some of these modules, prefixed "M", contain a memory by means of which it is possible to memorise the various adjustments needed for a particular model.

When one of these modules is fitted, switches number 9 - 12 select the memory options:
Switch 9 stores the settings of all the left hand bank of switches - servo reversing, stick configuration, etc.
Switch 10 stores the settings of all the adjusters.
Switch 11 stores the settings of all the trim levers.
Switch 12 turns the memory on or off.

The beauty of this arrangement is that you can store all the various settings for one model while leaving the transmitter controls in the positions required for a second model. By simply turning the memory on and off you can set the transmitter up for each model as required.

Returning to the switch bank, switch 2 sets up the PPM mode of the transmitter to suit either 7 or 9 channel receivers. The other switches serve various purposes depending on the soft module.

Reserve battery and battery change-over switch. A second battery can be fitted together with a switch to select the main or reserve batteries. The switch has three positions, the centre one of which allows both batteries to be charged simultaneously. The unit can be operated with the switch in the centre position.

Lets have a quick re-cap of the story so far. We have a basic transmitter which has two sticks controlling four channels with the option of two more channels being controlled by optional additional slider controls. By means of plug in soft modules, the controls can be used in various ways to suit different types of model.

The transmitter can be further expanded to give additional controls and adjustments which allow the use of still more soft modules which give more complex control schemes for the advanced, or specialist, user.

So far, so good. Now lets have a closer look at the soft modules. These units measure about 1 x 3/4 x 1/2 inches (25 x 19 x 12 mm) and incorporate an 18 pin plug which directs the various control inputs as required. Each is identified by a prefix letter ("B", "E", "M", "S" or "T"), a number and a short description. For example M2, HELI IV.

"B" Modules are low priced and intended for transmitters which have not been expanded. They can be used with expanded transmitters but do not allow full exploitation of the available facilities.

"E" Modules are intended for demanding specialist applications such as F3B gliders or competition helicopters. They need the expanded, or "Expert" transmitter.

"M" Modules include a memory which allows the values of trims, adjusters and switches to be stored. Their functions are similar to the corresponding "E" type and they require an expanded transmitter. Teacher/pupil operation is not possible with some of the "M" modules for technical reasons.

"S" Modules are specialised units which have been made in small numbers at the request of a small circle of users. If you have a special application, it is possible to have a suitable module made up to suit and this will receive an "S" number.

"T" Modules are intended for test purposes, or for coupling the transmitter to a micro-computer.

The following soft modules are currently available:
Number - Description - Specialised application
B1 - Standard - All-purpose use.
B3 - Allround I - Simple gliders.
B5 - V-Mix - Gliders, powered aircraft with V-tail.
B6 - Delta - Delta type models.
B7(8) - Heli I - Helicopters.
B9 - Flap I - Models with flapperons.
B10 - Nautic I - Model boats.
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E1/E1a - Allround II - Gliders and powered models with more complex functions, e.g. "snap flaps".
E2/E2a - Acro-F3A - Aerobatic models of the international F3a competition class.
E3 - Heli II - Advanced model helicopters.
E4/E4a - F3B - Model gliders of the international F3B competition class, with complex flap functions.
E5 - Heli III - Successor to the E3. Same range of applications.
E10 - Nautic II - Model boats with extra functions.
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M1 - Allround III - 'Memory' version of E1/E1a.
M2 - Heli IV - 'Memory' version of E5
M3 - F3B II - 'Memory' version of E4/E4a.
M4 - Acro-F3a II - 'Memory' version of E2/E2a.
M0 - Flying wing - Specialised module for flying wing models with 3 pairs of flaps and winglets.
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S1 - Twin - For twin engined models. separate or combined control of the motors.
S2 - Tandem Heli - For controlling a tandem rotor helicopter.
S3 - Elektro - For competition electric powered models. Flap control via throttle stick when motor is running, via slider when motor is stopped.
S5 - Flying wing II - Similar to M9 but with differential elevator for each pair of control surfaces.
S6 - F3B-V-tail - Similar to E1/E1a but with additional mixer for V-tail.

The unit examined for this review was originally supplied with a M1 module, but this was changed to an M2 module to give a better idea of just what the equipment was capable of and to give a direct comparison with other equipment reviewed by the writer.

It is very obvious that the thinking associated with German designed helicopter radios is very different from that of the rest of the world. In fact, most of the features normally considered desirable are incorporated but under different names and working in unfamiliar ways. For instance, the function normally referred to as "idle-up" is known as "take-off point" and is in fact operated by the throttle trim. If the throttle stick is set to the low throttle position, then the throttle trim lever can move the throttle over its entire range and the position set becomes the low throttle point. Thus the full range of the stick travel could give, say, only the last 10% of the normal servo travel.

The "throttle hold" feature is achieved by means of the "combi-switch" which transfers the throttle action to one of the slider controllers and allows the throttle to be put to a preset position without interfering with control of the pitch. This action overrides any limitation on the pitch throw in the normal manner.

A mixer is available to allow mixing of the collective and cyclic pitch inputs as required by moving swashplate systems. Unlike most of these systems, this one can be used with the Heim "Star-ranger", Robbe "Squirrel" and Graupner "Helimax" helicopters which (surprise, surprise) are all of German origin.

The whole process of setting-up appears at first sight to be rather complicated. However, actual installation in a model, followed by a period of use makes things much more clear. One or two things were slightly puzzling at first but these were soon sorted out. For others who may be having difficulty, the following notes may help:-

Adjuster 7 is referred to in the manual as setting the take-off point (idle-up). It is in fact a hovering throttle trim which is only effective on the centre of the throttle range.

Collective/cyclic mixing is turned off by setting adjuster 11 to one end point. Note that the particular end point chosen also decides the direction of the elevator servo.

The bottom end of the pitch range is fixed and the pitch throw adjuster only effects the top end of the pitch range

There are several ways of setting the throttle throw associated with the various options. On the normal throttle action the end point adjusters actually set the trim range - in other words, the idle-up range.

All of the various switches can be placed in a wide variety of different positions and a set of adhesive labels and blanking plates is supplied with each soft module so that the switches can be labelled to suit. This also means that the labels can be easily changed along with the module.

Perhaps by now you may have the impression that I am not very impressed - far from it! Its very versatility is a little confusing and one is reminded of the saying "Jack of all trades and master of none". In this case, however, it is possible to configure the set in the way that you want it instead of having to learn to use a particular layout - as you would with a purpose designed set.

All this and we still have not mentioned the fact that the dual rate facility can also give exponential control or that the trims work only on the centre of the stick and do not effect the end points.

The receiver is fairly compact for its type and the servos appear to be fully ball-raced types which did have a little more play in the gear train than one would expect from equipment of this quality.

A very neat charging socket is incorporated in the switch harness with a sliding cover to keep out dirt when not in use. Receiver battery pack is of 1200 mAH capacity and is enclosed in a substantial case. The particular example examined allowed the battery to rattle about inside this case. This, of course, is easily fixed.

There is so much of the novel and unusual in the equipment that an article on it could easily fill several pages of this magazine. In order to fit into the available space it has only been possible to dwell on the more novel features which, I hope, explains the somewhat unusual nature of this description.

A versatile and unusual set of equipment which would need to be used for some time to explore and appreciate all of its possibilities and virtues. The manual could, perhaps, be more helpful in this respect, though this is more a criticism of the translation than of the original item which would appear to be excellent.