The kit - Assembly - Main frames - The canopy - Installation and set-up - Flying - Conclusions - Specification
For some time now, Dave Wilshere has been asking me to review the original 'X-Cell 60' kit in its latest form. This is a logical move, for many reasons. The 'X-Cell' family has grown and grown and there are so many up-dates, together with 'Customs', 'Graphites' and 'Pros', not to mention the gas versions, that most people have probably lost sight of the fact that the original is still available, albeit in modernised form.
I resisted the temptation for some while, due to lack of time ("Oh no! Not another kit review!"), although the idea appealed to me. Then, suddenly, we didn't have a kit review for the December issue. At the same time, it suddenly ocurred to me that this was, to all intents and purposes, the existing World Championship machine and that this was almost certainly about to change. I, therefore, decided to grudgingly acceed to Dave's request and collected a kit from him so that construction could be started before the result of the recent world championships was known.
History relates that the championship was won by an 'Xl-pro', but we have already reviewed that. Yes, it is time for an up-date! All in good time.
This has now been around for some considerable time and there have been many changes and up-grades to the original form. I suspect that many of these would only be apparent to someone who has built one of the early kits - preferably fairly recently. One of the more obvious changes is that the servo trays are now of plastic, rather than the original wood. Here again, there have been changes and there is now an adjustable metal brace (Part No. 0578) which supports the front of the tray from the metal tank platform below it.
In earlier kits the fan shroud was supported at the front by screws which passed through the front bulkhead into the shroud itself. This has now been replaced by two metal side supports (Part No. 0548) which are attached via some of the screws which hold the motor mount between the frames. This gives a greater range of adjustment.
The flybar paddles are now of the 'Pro I' type (Part No. 0561), which have screw-in weights which allows you to adjust both the weight and the balance without dismantling things.
However, the biggest change is in the use of the Miniature Aircraft self-aligning clutch system (otherwise known as the 'Uni-Ball Dampened Clutch System', Part No. 0546), as used on the 'Xl-pro'. This system is being adopted for all of the existing Miniature Aircraft range (see last months 'Sales Pitch').
The packaging is quite interesting, in that all of the kit contents in their various bags are assembled onto a large sheet of cardboard and covered with a transparent plastic film. This bears labels telling you not to accept the kit, without checking the contents, if the seal is broken!
One thing which has not been changed is the now-famous two part tinted plastic canopy, which is kept separate from the other items in the box.
The actual make-up of the machine is what might now be termed as the 'conventional' model helicopter, with metal sideframes and boom, plastic undercarriage struts, plastic rotor head and tail gearbox and weighted wooden main blades.
One of the reasons why I decided to take on the review is that I had just totalled another machine of similar vintage to the 'X-Cell', which had in it a very good OS '61 SFR-H', which was now redundant. I had also intended to use the silencer from that machine but, here again, Dave Wilshere convinced me that I should use a Miniature Aircraft 'Nitro Pipe', which was working so well in the 'Pro'. With the choice of power unit and silencer thus settled, there was nothing to delay things any further.
At this point I referred to my review of the 'Pro' and was intrigued to find that the earlier kit, though different, followed identical assembly lines using the well established method whereby numbered bags of components match numbered sections in the assembly manual including the Miniature Aircraft ideas like the fact that the manual starts with a full list of each main assembly and sub-assembly - rather like a contents list. Another idea is that where each numbered bag has a plastic tube which contains all the smaller items, nuts, bolts, etc. heat sealed in compartments. As you work along the tube, opening each compartment in turn, you are fed the items in small amounts as you need them. This means that you don't have to go looking for a particular bag, or things which might be in other bags and you don't get confused by having too many items to sort through at one time.
I was impressed by this arrangement on the 'Pro', but I hadn't realised just how long this system had been in use on the 'X-Cell' range.
It was also good to be reminded just how good Miniature Aircraft instruction manuals are. These start off by telling you about the dangers of helicopter operation and give guidelines for safe operation. They then go on to tell you what you need to complete the model and follow up with a comprehensive list of tools, both essential and optional. Then comes that list of assembly sections. Only then do you come to the actual instructions which detail everything, right down to the last detail.
Full details are given regarding servo arm lengths, pushrod lengths and final alignment. If followed closely, these are all close to the optimum. This is followed by a list of all the items you will need to operate the model, notes on starting and stopping the engine, first flight adjustments and final trimming and tracking. Finally, there is a page giving full size drawings of all the fasteners involved. Very impressive.
The kit includes allen keys and loctite, and only a few other tools are required for completion. It would be pointless to go through the entire assembly step by step, especially as the manual does this far better than I could. However, the salient points will be briefly covered for the sake of the potential purchaser.
If you follow the suggested sequence of assembly, you start with the rotor head. The interesting part here is the 'Pro I' flybar paddles. Each of these can have up to four threaded brass slugs inserted to adjust the weight. The slugs are screwed in from the inner end of the paddles. I chose to use three slugs in each paddle. The beauty of this arrangement is that having chosen the number of slugs to use, you can fine tune the flybar balance by adjusting the position of the last (inner) slug. With this in mind, I set the flybar centrally in its cradle and then screwed each paddle on the same amount, giving a completely symmetrical flybar. Having screwed the slugs fully home, only then did I set the balance by moving the slug on the heavier paddle. Actually, I had to move it quite a lot and then I realised that I should have given a little more thought to the selection of the slugs on each side, since the weights could vary considerably. However, the result was a symmetrical, balanced flybar - far better than running an offset flybar to obtain balance. The paddles are hollow and have end caps which have to be cyanoed in place. In fact, the fit is so good that the final joint is almost invisible.
The only point of note here is the elevator swing arm, which Tim Court commented about in his review of the 'Gas Graphite'. I really cannot see the point of ballracing this as it moves quite freely, without slop, and the actual angular movement is so small that ballraces would be wasted. The whole of the top half of the main frames, including the swashplate and washout mixer can be completed before adding the engine. This is very convenient since it can be stood up on the lower edges of the frames, yet is light enough to turn over as required. Once the engine is added, you have a hefty 'lump' to manipulate.
Very comprehensive notes are supplied regarding the fitting of various engines and the self-aligning clutch system. The fan is fitted by means of two tapered collets, one each side (upper and lower). and various collets are available to suit your particular motor. A few motors require the crankshaft to be slightly shortened and this is noted where applicable.
The crank on the 'SFR' is identical to the later 'SFN' and no problems were expected. However, the 'SFN' is supplied with a 1 mm thick washer which must go between the fan hub and the motor. The 'SFR' does not have this and I needed to obtain one. Attempts to fit the motor without this produced problems with the collets meeting inside the fan and the starter shaft fouling the end of the crankshaft.
This actually provided the answer to a small mystery: When I built the 'Xl-pro' I had similar problems. Reading the 'X-Cell 60' instructions produced the information that the OS '61SX-H' used in that machine should also have been supplied with a 1 mm washer. Mine wasn't!
If you are building either machine, do check the balance of the fan on a 'Hi-Point' balancer or similar. I did this on the 'Pro' and had no problems. I didn't on the 'X-Cell 60' and found it necessary to do so at an early stage in the flying to prevent the canopy 'drumming' and the tail rotor pushrod from 'buzzing' (both on tick-over). The problem is the moulded plastic fan, not the turned metal hub. Remove material from the back of the fan as required with a large size drill - don't drill right through! MA do supply a machined aluminium fan as an up-grade (Part No. 0579-4).
The correct installation of the clutch is quite critical. It is essential that there is some vertical play in the clutch bell and pinion. A special shim is provided to set the clearance between the clutch and the fan hub (there is no direct connection between them). However, if there is no vertical movement in the clutch bell, the system will not work properly.
The radio tray is fully described in great detail and there is really very little to do other than decide where you are going to mount the switch plate. There are two locations for this; on the left side (which will need a hole in the canopy to operate the switch), or at the left rear (where it can be operated by swinging the canopy forwards. The plate also includes a location for a gyro control box, but if mounted in the rear location this is partly obscured by the fan shroud support. The easy way out here is to use a linear gyro where the gain is set from the transmitter. In this case, you can use the control box location to mount a charging socket.
The servo location and control link lengths are all fully detailed and the results are very close to optimum.
The cyclic and collective pitch systems are what are sometimes known in the USA as 'direct control' - one servo to each function. In Europe, the system used would be called 'mechanical CCPM', which simply means that the swashplate moves up and down for collective inputs and that this is mechanically mixed with the cyclic controls. Just how this is done on the 'X-Cell' is ingenious and, while not as good as the system on the 'Xl-pro', very smooth in operation, totally solid and free from any form of interaction.
The 'Nitro Pipe' silencer used simply sits on top of the manifold to which it is joined by a short length of silicone rubber pipe. The rear support used in this case was a simple bracket made from coathanger wire (this is soft and easily bent, and it doesn't fatigue). It is important to obtain a good solid joint between the silicone joiner and the manifold and silencer. If it moves, it will melt the canopy (look at the photos and you will see how I know).
Ah yes, that beautiful canopy! I had always wanted to join and paint one of these and I intended to use the system advocated by Ray Hostetler of cutting the flanges on the canopy halves to different widths and then introducing cyano to the outside by dripping it onto the wider flange, a bit at a time.
Enter Dave Wilshere again who persuaded me to hold the whole thing together by bulldog clips (actually, he lent me his clips) and then running cyano down the inside and letting it pool in the nose. He didn't tell me that this would cause the canopy to blush! OK, well it did clean off quite easily using lighter fuel. Dave offers a joining and trimming service if you need it. Next time, I'll do it my way. Yes, Mr Schoonard, I do know that the manual tells me not to use cyano!
Dave also suggested using silicone sealer where the canopy sits on the side pillers rather than the fuel tubing provided (grease the pillers first). I'm not sure about this since it seems that the main result is that you have to spread the canopy further to get it in position.
The material itself seems happy to accept most types of paint and I used the usual 'Dupli-Color' spray. Did you know that the manufacturers have changed this very useful paint to a new acrylic formula which is not compatible with the earlier cellulose - but that's another story!
Masking the windscreen is very straightforward. Despite the advice of various parties, I still prefer to use Sellotape for the actual edge of this since it gives a sharper line. The rest of the area can be covered with almost anything, but the usual paper 'Masking Tape' works well here.
For some reason, this particular kit came with the 'Pro' decal sheet rather than the well-known multi-colour type. Checking with Motors and Rotors showed that the only decal set now available had a colour blend that didn't really suit the main colours decided upon. Look at the pictures of 'X-Cell' machines at the world championships elsewhere in this issue and you will see that most of them have red 'X-Cell' logos. Where did they come from?
The servo positions are all already decided for you and there are only so many possible locations for the receiver, gyro and battery. Having decided where the switch will go, your only problem is finding a tidy layout for all the wiring. It is possible to lead all the wiring in a single loom between the servos and the standard servo lead length is not too far short of the optimum. As usual, it all gets a little messy when the wiring arrives at the receiver. It has already been pointed out that the advised linkages are very near to the correct figure and the recommended pitch figures given in the manual are also a good starting point.
Having completed and flown the model exactly as per instructions for the purposes of this review, my own preferences made me decide on the following minor changes: 1 Fit the optional head button. 2 Change the moulded plastic tail blades to the optional carbon type. 3 Change the tank plumbing slightly.
The head button is a definite necessity and is the best and cheapest up-grade available. I simply don't like plastic tail blades. I have always thought that the rationale behind the 'X-Cell' tail blades (getting the CG forward by adding material at the root leading edge) is a good one, but the variations in plastic density can make them difficult to balance. In fact, the blades supplied in the kit appeared to balance perfectly, but there was a very marked vibration on the tips of the tailplane which disappeared when carbon blades were fitted. Investigation showed that the spanwise position of the CG of the plastic blades had a difference of about 3/16th of an inch. Miniature do offer carbon blades, but these are actually of NHP origin. I also reduced the tail rotor diameter to 10 inches as recommended by Messrs Youngblood and Wilshere. The tank plumbing advised actually has the feed pipe going into the tank well above the tank centre. When the tank is below half full the application of positive 'G' can cause the motor to quit. This happened to myself at an early stage and later to Dave Wilshere when we took the flying shots. Moving the exit point down onto the tank centreline eliminates this.
When the 'X-Cell 60' first appeared, I remember that all kinds of claims were made for the weight of the finished machine. Well, without making any effort at all to keep the weight down, this one weighs nine and three quarter pounds with 200 gram main blades. That's an interesting mix of units! Let's try again. This one weighs 4.43 Kilograms with 7 ounce main blades. So much for metrication! It is a special pleasure to embark on the flying of a brand new helicopter which is fitted with a well-tried and set up motor. Until very recently, this motor had always been run on castor fuel. A recent switch to 'Superglo 5%' needed some leaning of the mid-range mixture, but this was done when it was still in the old model. Before fitting it to the 'X-Cell' it was stripped and de-varnished (forget the oven cleaner, John Bottomley, and try a nylon pan scourer). The outside of the motor was cleaned by soaking in a strong solution of 'Persil', with amazing results. Despite being some 11 years old, the result is a sweet-running motor.
All of which means that I could concentrate on the helicopter straight away. With the advised set-up, the first lift-off had the model hovering with the throttle stick in the middle and the blades in track. The advised position of the tail rotor bellcrank was near enough spot-on and the only requirement was a touch of right cyclic trim. Looking back at the 'Pro' review, the same was true of that machine, both before and after it's early 'ding'. A great tribute to Miniature Aircraft.
In no time at all, I was enjoying myself with basic manoeuvres like loops and rolls and plenty of autos. I did find a need to increase the amount of negative pitch to get good autos and it still needs more. Getting the maximum pitch range needs careful adjustment of the linkages and the radio. Since then, the one limitation has been the fear of bending it before we have the flying shots in the can. despite this, I am really enjoying flying the model although it doesn't have the outright performance of the 'Pro'. A helicopter with a lot of performance can be very exhilerating, but also a little wearing. I find this combination to be very relaxing.
The flying shots were obtained with Dave Wilshere doing the flying while I took the pictures. Dave commented that the set-up was a little docile for his taste - but I didn't get to fly it again that afternoon! You can spend a lot of time getting a particular machine set up to your taste and I haven't yet got the rolls quite right. It was refreshing to find that Dave had similar problems because it proves that it is the set-up, not the machine. We agreed that it is a combination of pitch/throttle curves and maybe tail mixing.
One thing that I like very much is the fact that the tail rotor stops on autos. Most people prefer the tail to keep turning nowadays, but it is nice (and, in my experience, quite rare) to have a model where the clutch works that well!
The advised set-up gives an almost constant speed set-up straight out of the box. Dave says that this is normal, yet on some other machines you could work on this forever. This machine has been around for quite a while and I find myself wondering why I have never tried one before. If I like it now, what would I have thought of it five years (or more) ago?
The object of the exercise was to discover whether the original 'X-Cell 60', in its latest form, had anything to offer in a world where up-grades seem to be almost obligatory. The answer is yes. Obviously, if you have ambitions of becoming the next world champion, then you need all the performance that you can get. However, if you just want to fly helicopters, throw them around a bit and compete in the odd contest, this machine has everything that you need. After all, it was good enough to win the world championship a mere two years ago.
In terms of value for money it seems hard to beat. You could buy two for the price of one 'Pro', and that machine is very good value.
It must be very obvious by now that I like it a lot. Thank you, Dave Wilshere and Miniature Aircraft USA.
|Manufacturer||Miniature Aircraft USA, 3743 Silver Star Road, Orlando, FL 32808, USA. Tel: (407) 292-4267|
|UK Importer:||Motors & Rotors, Unit 2, 13 Smith Street, Watford, Herts. WD1 8AA. Tel: 01923 465712. Fax: O1923 225233|
|Main Rotor Diameter||57.25 in (1455 mm)|
|Length||53.5 in (1360 mm)|
|Height||16.25 in (413 mm)|
|Tail Rotor Diameter||11.1 in (282 mm)|
|Main gear ratio||9.0:1|
|Main to tail gear ratio||1:4.37|
|Weight||9lb 12oz. (4.43 Kg)|
|Powerplant||0.61 cu. in. (10 cc) two-stroke glowplug engine|
|Control Requirements||5 servos and a gyro|