Nigel Hawes reviews the GWS kit - 28/10/10
If you’ve been reading my RCM&E Fly Electric column for some time then you’re probably aware that I’m very much an ‘old school’ balsa basher. Whilst ARTFs and foamies certainly have their place in aeromodelling, from my own point of view one of the greatest pleasures of the hobby has to be an enjoyable build. As a result I’ve possibly been a little blinkered to the growing number of designs made from foam - perhaps even a little dismissive of them at times. That said, many regard the foam-based TwinStar as an extremely significant electric model and indeed I have had a couple myself!
However, one product that caught my eye recently has gone a long way to changing my previous disregard for such models - the GWS Formosa from J. Perkins. At just under 36” wingspan and with classic patternship looks this model is probably the best value electric design you’ll find anywhere, given the comprehensive nature of the kit, performance on standard gear and the sheer fun of flying it.
Although I rarely use anything other than GWS receivers and servos, I haven’t been that impressed with their range of aircraft kits, that is, until now. They’ve more than redeemed themselves with the Formosa, and the fact that it’s selling in droves worldwide is an indication of just how ‘right’ it is.
Whilst the Formosa is not ARTF, the major components are large and the model takes shape very rapidly, indeed, it should take just two or three evenings to assemble depending on how fast you build.
One striking thing about the Formosa is just how complete the kit is - you literally get everything except the radio gear and batteries. Motor, gearbox, propellers, linkages, hardware, accessories - even elastic bands and glue are provided! The elastic bands are for holding the fuselage sides together whilst the glue’s setting, but I would advise against using them as they can badly dent the foam - nice thought, though. When you consider the ‘holiday brochure’ quality of the instruction manual and high quality box, the price could easily be misinterpreted as a printing error.
The Formosa is derived from expanded polystyrene (EPS), the material that forms the basis of most foam wing cores (though the Formosa enjoys a much higher density type to maintain integrity of the components). As I rarely build foam models the whole experience was quite new to me, and the question of adhesives raised its ugly head. GWS supply a tube of their own glue (which smells suspiciously like the rubber solution used to repair bicycle punctures) with complementary advice that its curing time is quite considerable, and that other adhesives can be used to speed up the build. 5-minute epoxy is given as an example but this is quite heavy, so I decided to see what else the market has to offer.
Deluxe Materials have some of the finest adhesive technology in the business - I’ve been using their Roket cyanos and Roket powder to excellent effect since discovering them. This being the case I got in touch with John at Deluxe to ask if they had any foam adhesives that might be suitable for a model such as the Formosa.
Needless to say the response was affirmative, and before long I had the pleasure of trying some of their unique products, many of which have been painstakingly developed specifically for modelling purposes - something that Deluxe Materials seem to excel at. Take their ‘Foam Blaster’, for example - a foam-friendly cyano accelerator. Nothing new there, you might think - but there is a big difference. There are a number of odourless cyanoacrylates available that are suitable for use with foam, however their use can be completely negated by spraying on a kicker that isn’t foam-friendly. This is because the carrier fluid (in which the active ingredient of the accelerator is held) may not be compatible with certain foams. With this in mind Deluxe Materials went to a lot of trouble to find a product that is safe and effective to use with all the foam types that are available for modelling applications.
In the case of joining the two Formosa fuselage mouldings, Roket Odourless and Foam Blaster made the task extremely rapid and fuss-free, without stinging my eyes or reducing the fuselage to a dissolved blob of foam! I’ll be looking at a completely different example of foam adhesive technology in the next instalment of Fly Electric, however, in the meantime it’s worth noting that Deluxe Materials products are available from Irvine-stocked model shops.
BACK ON BOARD
Before the Formosa fuselage mouldings are joined the rudder and elevator snake outers need to be cut and glued in place at their exits - and this was the first of only two niggles I had with the whole build sequence. The instructions direct the builder to cut each pushrod outer tube to 370mm in length and glue them into their exits with 10mm protruding. Trouble is, when the fuselage halves are joined you can barely see these tubes anymore, let alone support them! To overcome this one can feed the pushrods through from the rear end, whilst increasing their length to 385mm, thus saving a whole load of fiddling.
The power unit supplied with the Formosa is the ubiquitous GWS EPS 350 (Electric Power System), which is a common package in many of their kits. It uses a sub-400 brushed Mabuchi motor with a simple ‘C’-type plastic spur gearbox running a pretty high ratio - in this case 5.3:1, making it capable of turning the supplied 9 x 7” and 10 x 6” props on seven AAA cells. The props, incidentally, are the bright orange slow-fly type that many indoor and lightweight outdoor models appear to favour. There’s also a push-on rubber safety spinner which remains remarkably true and well balanced when fitted. In an impact situation this almost certainly reduces any risk of damage and / or injury. The whole unit is simply screwed to a hardwood stick that’s then glued into a slot in the front of the fuselage assembly, having first made sure that the output shaft exits the nice little cowl moulding centrally and with the correct thrustline. All in all it’s very well thought-out and sorted, borne out by the model’s flight performance - straight and true without any directional or pitch change whatever the throttle setting.
WING AND TAIL
The wing and tailplane are one-piece items, with moulded-in grooves to show where to cut (and so remove) the ailerons and elevators. Use a brand new scalpel blade here to ensure a clean cut; a not-so-sharp blade will remove ugly chunks of the foam resulting in an awful union. Cutting about 1mm from each end of the removed control surface will ensure that clearance exists - common sense, but not mentioned in the instructions. Also it’s a good idea to carefully chamfer the control surface leading edge to a point so that it can be hinged effectively. The instructions tell you to do this for the rudder, but not for the ailerons or elevators.
Plastic tube journals are supplied for the aileron torque rods, though the internal diameter of said tube is a little too large for the gauge of piano wire that’s supplied. This means that whatever you do there’ll always be some slop in the ailerons which you can’t cure - not that it creates a problem in flight. As for the elevator, this is supplied as a single item with a metal wire joining each surface, adding greatly to the overall strength. The tailplane assembly glues into the fuselage recess having first removed a chunk of the rear fuselage, which is glued back in place afterwards.
Models this small are often one-piece, though the Formosa has a removable wing for servo access. Two GWS Naro servos work the rudder and elevators, whist a third operates the ailerons. The wing uses plastic locators at the front and a strong metal bolt at the back, all of which are considerably stronger than the surrounding foam. The canopy, on the other hand, uses dowel connectors at the back with a small circular magnet at the front, allowing it to be easily lifted off for battery changing. Some owners have complained about the canopy flying off in violent manoeuvres, though as yet I haven’t lost mine despite all attempts! As long as everything’s positioned correctly this arrangement is more than ample, and it certainly beats having to unscrew a hatch to change the flight pack.
My only other gripe about this model comes with the linkages. Running 18swg piano wire through outer tubes (in the case of the rudder and elevator) is all very well, but the recommended set-up and adjustment method (involving a ‘Z’ bend at each end and a ‘V’ shape kink that can be squeezed or expanded for adjustment) is both fiddly and awkward. Fortunately, Ernie Thorpe of Moorcraft Engineering has considerable foresight when it comes to the recent growth in indoor and park-fly models, and has produced a superb set of pushrod connectors for the Formosa that make the job a complete doddle. To start with, the shaft of the connector is 1mm diameter, i.e. exactly the same as the holes drilled in Naro servo output arms, so there’s no slop.
Secondly, a collet keeps the connector in place with the turn of an Allen key, whilst adjustment of the pushrod is easily carried out by threading it through to the control surface neutral position and nipping up with the central Allen grub screw. Simple but ingenious! Granted these precision engineered connectors cost £6 for a set of four, but it will save more than £6-worth of tearing your hair out getting those awful ‘Z’ bends and ‘V’ shapes to behave.
Those familiar with GWS kits will recognise their legendary ultra-light wheel rims, which you either love or loathe. Personally I think they spoil what is otherwise a cracking-looking model, although they do work for anyone who needs an undercarriage equipped model - at least, for a short while! Yes folks, I’ve heard several reports of either the u/c or the mountings failing with anything other than a greaser of a landing. As most of my flying is flat field from grass I opted not to fit the u/c, saving a few grams and making the model far more suitable for my purposes.
As a result the airframe looks a lot cleaner in flight, and I should imagine the reduced weight and drag probably help in some small way.
The Formosa is designed to use a 7-cell flat pack of AAA NiMHs, indeed there are several types available from battery distributors. After testing a variety of AAAs and finding that some have terribly poor voltage stability above 5A, the two that seem to work best are the LG 700 AAAs (available from many shops) and the KAN 650 AAAs from Overlander, which are outstanding in this application and have the best voltage stability of the lot.
At less than £15 (2004) a pack this is indeed a cheap intro to electric flight. A GWS 8-ch micro Rx and the smallest speed controller I had, a Jeti 18A (I’d never operated indoor or park-fly type models before!) completed the set-up, with ample room for these components without the usual wiring ‘spaghetti’ that small models often seem to generate. In its standard form using 7 cells, the EPS 350 and ‘C’ gearbox draws 7.8A with the supplied 9 x 7” prop, and 6.8A with the 10 x 6”. These are static figures, which you’d expect to drop by a good 15% when unloaded in flight.
For extra performance it’s tempting to either increase the cell count to 8 and / or the prop diameter and pitch, but either course of action will significantly reduce motor life. Truth is, this little motor is working pretty hard with the supplied set-up and the bottom line is that if you want extra performance an entirely different powertrain should be considered. In next month’s Fly Electric I’ll describe a modification to the Formosa that makes a world of difference. In the meantime, however, the purpose of this feature is to show how it all goes in standard form.
Adding the moulded cowl and attractive decal set really finishes the model off nicely.
FUN FROM THE OFF!
An underarm lob saw the Formosa away without fuss and once trimmed the fun began. Whilst the model is amply powered it’s certainly not overly so (45 watts does have its limit!) but all this means is that you have to work for your manoeuvres, which is no bad thing. From level flight the model will loop, roll consecutively, bunt and fly inverted, so I’d say the powertrain supplied has been pretty well matched. One thing you do notice is that the throttle is wide open most of the time as you can’t do an awful lot at lower throttle settings; nevertheless it still returns 6.5 minute flight times from the KAN 650 AAAs, suggesting an average flight current of around 6A.
The C of G shown is extremely safe, and after a couple of flights I think most operators would probably experiment with more rearward positions as it’s just a little on the nose-heavy side where shown. After a flight or two for familiarity the Formosa cries out for the pilot to be daring, and you can’t stop yourself from trying a few tricks.
My favourite is to climb to a good height, chop the throttle, put the sticks in the corners and watch this amazing little model spin like a sycamore leaf until I chicken out! Centralising the sticks results in an almost instant recovery and it gives so much confidence that you leave your pull-out point lower and lower every go. When you get bored with that you can do the same inverted, where you have to think about things a little more as the recovery isn’t quite as quick, and when it does stop spinning the model’s still inverted!
For a mediocre flier such as myself a model like this is an asset in learning new tricks - those of you who have seen me fly will know I’ll never win any competitions requiring flying skill! In fact inverted flight was something that I’d always struggled with, until the Formosa came along. For some reason I had no inhibitions teaching myself to fly inverted using this model, to the point that I now regularly launch it underarm and inverted, catching it on the elevator and performing the whole flight upside-down.
Clearly, this is a confidence inspiring model.
With 3 or 4 battery packs to hand you can have an absolute ball with the Formosa, and I’ve no doubt at all that it’ll improve your flying one way or another. It’s predictable, viceless and reasonably capable on the supplied powertrain... it’s simply the best fun you’ll ever find for the money.
ROOM FOR MANOEUVRE
Cheap, simple and with pleasing looks and performance, the Formosa is high on the list for anyone still mystified by electric flight and looking for a cheap entry. But for the growing number of current electric flight enthusiasts it can also be considered as an excellent platform to progress into areas such as entry-level brushless and Lithium-based flight batteries. Studying the various internet discussion groups it appears that this model has taken the aeromodelling world by storm - some examples have been extensively modified to give fantastic performance and have even managed a full F3A pattern schedule!
The unskinned foam does inevitably get marked and dinged in time, but that’s simply the nature of the beast - at this price you can afford to have at least one spare. Being completely hooked on the Formosa and now owning two of them, I’ve been doing some modifications to make it really perform without breaking the bank. Next month I’ll reveal how to squeeze more out of this cracking model to give it the performance it deserves.
Model type: Electric sports aerobatic
RRP: £32 (2010)
Manufactured by: GWS
UK distributor: J. Perkins
Wing chord: 7'' (mean)
Wing area: 245 sq. in.
All-up weight: 14.5oz
Wing loading: 9oz / sq. ft.
C of G from l.e.: 80mm (recommended)
Control functions: Aileron, elevator, rudder, throttle
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