Cockpit SX - Review

by Mike Shellim

last updated 20 November 2006

This review is loosely based on the ones I wrote for QEFI and RCMW. It's now been updated, in the light of further experience since the magazine articles were written. For a basic description of the set, please see the Cockpit SX Home Page.

The set was given an unusually thorough workout, being used to fly seven different models - a full list is at the end of this page. Enjoy!

Ergonomics.

The Cockpit SX has some unique and rather clever ergonomic touches.

Aerials

For regular outdoor flying the standard aerial is just fine. However, for DLG and indoor flying, the aerial is a little cumbersome. For these applications, consider purchasing the optional stub aerial . I use this for DLG and am very happy with its. Although range is said to be less, I have had no problems.

Incidentally, the stub aerial for the Profi 4000 also fits the Cockpit SX, however it's shorter and fatter than the Cockpit SX version. Do not use these. RF is a black art, aerials have to be tuned to the RF output circuit and clearly the 4000 is not correctly matched to the SX, otherwise Multiplex would not be manufacturing a different unit! Best to go with the unit designed for the job.

Balance with the standard aerial is fine when used with a neck strap, but when hand-held it tends to tip down. Conversely the stub aerial is fine when hand held, but with the neck strap it tends to tip up! However, neither situation is a problem, as most pilots will use a neck strap with the standard aerial, and hand hold with the stub aerial. Hand holding is easy, since the Tx is very light.

When not in use, the standard aerial can be retracted in a recess in the case.

Build Quality

Although moulded entirely from plastic, the Cockpit SX feels solid and reassuring, rather better than the Royal Evo in fact. The absence of a keyboard and the use of a fixed LCD panel help a lot, as does the use of screws to hold the case together (instead of a pair of releasable fasteners on the Evo). The downside is that getting into the case is more difficult, involving unscrewing 7 Torx screws. But it's a price worth paying. At least a Torx key is provided.

On some units I've seen, there is a minor moulding error which prevents the aerial from sliding out easily from the recess (it should slide out under its own weight). This is easily fixed using a file, but you will need to open the case.

The switchgear comprises largely of slide-action switches, rather than the more expensive - and smoother - miniature toggles. However the switches seem very tough, and much less likely to snap off as a result of knocks.

The quality of the sticks is entirely adequate if not quite up there with the very best Japanese units.

NiMH Battery

A six-cell 1500 mAh NiMH battery is provided, It contains an integral thermal fuse. The battery lasts 7 hours or so from a full charge - easily enough for a day's flying. An audible low battery alarm kicks in when the voltage drops to 7V.

Unlike the Royal Evo range, there is no battery management circuit, but in practice I did not miss this.

Charging is via a multifunction DIN socket next to the aerial. The charger plug is the same as on the other MPX sets. I was happy to see that the Tx can rest on its back while it's being charged. No charger is supplied.

The Synthesiser

The Cockpit SX incorporates a frequency synthesiser, so no crystals are required. Instead the desired channel is selected via a software menu. To access the menu, simply switch on while simultaneously depressing the digi-adjuster knob. Select the desired channel with the digi-adjuster, switch off and on again, and you're done. It all works very smoothly indeed.

Unlike the Evo which uses an interchangeable RF module, the synthesiser on the Cockpit SX is integrated on the motherboard, therefore the frequency band cannot be changed. This could be a consideration if you wish to take it to another country.

The Tx performed flawlessly during flight tests. I should point out that my mobile phone is always switched off while flying, In accordance with BMFA and MPX guidelines.

Model Types

The Cockpit SX supports three aircraft model types (Easy, Acro and Glider), and a heli type with various options for swashplate configuration. For comparison of features for the aircraft types, see the Feature Matrix.

Mixing

Mixers on the Cockpit SX are unusually comprehensive for a beginner/sport radio. Glider flyers in particular will delight in the support for four-servo wings. Each pair of control surfaces (i.e. aileron and flaps) can be tuned independently for response to the following controls:

It's worth repeating that the flaps and ailerons can be adjusted independently for the above mixes - this is pretty darned good for a budget radio! So for example you could have less snapflap on the ailerons than the flaps, if that's the way you fly. You can even have differing amounts of aileron differential on the inboard and outboard surfaces. When you factor in flight phases (see below), clearly Multiplex's claim that it will support F3X sailplanes is not just hype.

Indeed I have flown my Sting F3F 2.9 meter racing glider, equipped with 6 servos, with it the Cockpit SX with no problem at all. Of course the SX is no substitute for a well programmed 4000, but really the only major features that I missed in flight (as opposed to while trimming) were multi-point curves for elevator compensation and snapflap, and a switch to disable the Spoiler stick. Also the servo channels cannot be reassigned as on the Evo 9/12, mc3030 and mc4000.

Several other mixers are provided, including three free mixers. For a full list, please see the Feature Matrix.

Servo Neutral Offset adjustment

A really nice 'advanced' feature is the Servo Neutral Offset function for flaps and ailerons. This permits the full range of servo rotation (+/- 40 degrees) to be used, even if the control surface movement is grossly asymmetric.

The prime example - which many F3X pilots will be familiar with - is crow brakes where the flaps may move 80 degrees down but only say 5 degrees up. Most radios insist that the servo centre corresponds to the neutral flap position (for the crow mixing to work properly), leading to wasted servo movement in the 'up' direction. By allowing full servo movement to be achieved, the Cockpit SX allows you to use a shorter servo arm. This decreases wear in the servo gears, and reduces linkage slop, vital for accurate control.

Incidentally, even the Profi 3030 does not provide this feature. The Evo can do this if you choose a special mix. The ultra-flexible Profi 4000 can be programmed to emulate this feature (it's a tricky Tx for the non-technical user, however). The Cockpit SX solution is the neatest.

While this feature is useful for F3X models with crow brakes, it will also come in handy for DLG's with their micro sized servos.

Automatic Differential Suppression

The Cockpit SX - like all MPX systems - offers automatic differential suppression. This feature is useful for glider and electric models where applying spoiler causes the ailerons to be raised. In this condition, you need all the downgoing aileron travel you can get, in order to obtain a decent roll response. However, differential reduces the downgoing aileron movement. On the Cockpit SX, differential is gradually cancelled as spoiler is applied, thus maximising roll response.

Flight Phases

Flight phases is another excellent feature. This allows you switch between three (four for helis) sets of settings - all at the flick of a switch during flight. So for example a glider could have a 'Normal' mode, a 'Speed' mode (reflex flap), and a 'Landing' mode. Each phase can store different trim settings, aileron diff and flap presets. The speed of switching between flight phases is adjustable in three steps.

The implementation on the Cockpit SX works well, although flight phases are identified simply by a number 1-3 (you cannot assign meaningful names like 'launch', 'landing' etc. as with the Evo 9/12).

Flight phases are disabled by default.

Absolute servo end points

Unlike some systems e.g. Futaba 7C, the end points on the Cockpit SX work as proper electronic end stops, even if the servo is driven via a mixer. Contrast this with the EPA adjustment on the Futaba 7C (and other Far Eastern radios) which only works properly if the servo is driven directly.

This is useful when setting up a V-tail on an aerobatic glider. It allows you to set up maximum throws on the rudder and elevator functions, without risk of damage to the linkages if you push the stick in the corner.

Non Linear throttle response

One slightly puzzling feature I noticed was the 'kinked' servo response from the throttle stick. Under certain circumstances, moving the throttle stick can from idle to mid throttle can have no effect at all on the servo, with all the servo movement occurring between mid and max stick!

The key is the 'idle trim' implementation - as you move the idle trim forward, the response to the throttle stick gets progressively non linear in the manner described above.

To minimise this issue with I/C models, make sure the idle trim is as far back as possible. For electric models, idle trim is not necessary, so simply set it all the way back (minimum idle). Not only this will provide a linear throttle response, it will also ensure that your ESC recognises the slow throttle position for its initialisation checks.

Incidentally the Royal Evo can be coerced into exhibiting the same behaviour (by setting the idle trim range to maximum).

Programming

The Cockpit SX's programming interface is beautifully simple and elegant. All the programming is done from a single 'digi-adjuster' knob - that's the big round knob under the on-off switch. And there are only two things you can do with it: push it or twist it. (Compare the simplicity of the Cockpit SX with the Futaba 7C which has a total of five programming controls).

The programming screens are hierarchically grouped under various main headings ‘Setup’, ‘Control’, ‘Mixer’, ‘Servo’, ‘Memory' and ‘Timer'. This makes it very quick to 'drill down' to the required screen. Once in a screen, you twist to knob to cycle through the options, click to select.

Ex Futaba and JR users will need a little familiarisation - a few minutes is all it takes, but at the end of it you'll never want to go back. If you do get stuck, the Cockpit SX manual is beautifully produced and very comprehensive - a world apart from the usual Far Eastern fare. Beginners will want to spend a little time reading the relevant sections before starting, however.

Conclusion

A lot of clever thinking has gone into the Cockpit SX, from the excellent ergonomics, to the logical way that mixers are programmed, and the delightfully simple single-knob user interface. And of course that synthesiser is just so-ooo convenient.

Yet the Cockpit SX also manages to pack a remarkable programming punch for such a budget system, with an excellent set of mixers (for F3X gliders and fun-fly aerobats), flight phases, and absolute servo limits.

Negative points are pretty minor really. The standard aerial is too long for easy DLG and indoor flying, but the optional stub aerial provides a solution (although be aware that range is reduced). The only other gripe is the non-linear response of the throttle channel (though this can be minimised by setting the idle trim as slow as possible).

Comparing rival brands like JR and Futaba, none offer a synth let alone flight phases at anything like this price point. None can claim such a clever programming architecture. Indeed you have to look at Multiplex's own Evo 7 to find a genuine rival. The Evo 7 has similar programming capabilities, and a separate RF module. The Cockpit SX however is smaller, simpler, easier to program. What seals it for me though is that the SX somehow feels a lot more solid than the Evo. It's also cheaper.

If you think I'm pretty enthusiastic about the Cockpit SX, then you'd be right. It's not a replacement for the Evo 9/12 or Profi 4000. It is, however, an excellent system for advanced beginners, and intermediate flyers. It also makes a fine lightweight second set for 'big box' owners.

At the time of writing, the Cockpit SX seems to have carved itself a unique place in the market. It will undoubtedly be a huge success for Multiplex, and I can see it introducing a lot of new users to the brand.

Specifications

Channel count

7 Servo channels

Model memories

12

Transmission

FM PPM, 10 kHz channel spacing

RF channel selection

Synthesizer with menu-based selection

Servo signal format

UNI 1.5 ± 0.55 ms

Current drain

~ 20 mA excl. RF section
~ 200 mA incl. RF section

Dimensions

Length approx. 220 mm
Width approx. 200 mm
Height approx. 60 mm

Weight

Approx. 785 g incl. battery

Price

See suppliers for latest

Models used for flight testing

Gliders

Power

Heli

My published reviews of the Cockpit SX

QEFI - September 2006, biased toward quiet flight.
RCMW - November 2006, mixture of i/c and quiet flight test.

Available from Traplet Publications