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Sting Review by Mark Passingham

Originally featured in QFI 54

Photos 1 2 3 4

I first saw the Sting last year at an F3F race in Portugal. The model was being flown by the designer and builder, Vaclav Vojtisek, and he did rather well with it, a top ten placing if I remember correctly.

The model generated a lot of interest and he could have sold the examples he had with him several times over. American, Charlie McMurray was the lucky punter who managed to obtain first refusal on Mr Vojtisek's own model and went away a very happy man at the end of the week. Espen Torp also managed to get hold of one and did rather well with it a few months later at the 2000 Welsh Open. He flew it for most of the competition, recorded a 35 second run on the second day and went on to win the competition.

Our illustrious editor and I managed to have a fly of the original model in Portugal during one of the days we were waiting for the wind to blow. Unfortunately the conditions weren't particularly thermally while we had the transmitter in our possession so we were unable to really put the model through its paces. The time I did spend on the sticks left me suitably impressed, so when Kevin asked me a few months later if he could 'tempt me to the Dark Side' to do a review on a moulded model, I didn't need much persuading.

The Model

The Sting is an out and out F3F machine. At 2.8 metres it is my ideal size for F3F, but it would now be considered too small for an F3B machine, as the current trend is for 3 metres and over. The layout is fairly conventional; a three-piece wing and a one piece V tail. The wing section is HN1038; a new one on me, so I had to go and look it up. It's a thin, low camber section, ideal for high-speed flight at 8.15% thick and 1.52% camber.

First Impressions

The plane arrived in the biggest, sturdiest transit box I have ever seen. I was so impressed with the construction of the box I nearly took a photo of it but fortunately I managed to get my anorak off just in time. Ten minutes work with a screwdriver and I managed to gain entry and extract my new toy.

The contents did not disappoint in any way. The fuselage is a beautiful moulding with a couple of unusual features. The most noticeable is the seam line, which is horizontal and runs along the side of the fuselage rather than the more usual vertical seam. This is a very practical idea as it means that the fiddly bits to mould, the wing seat and the V tail mounting, do not have a seam through the middle. This would suggest that the lay-up is that much simpler to do, which should result in a stronger, lighter final product.

Also unusual is the inner nosecone, which is a complete moulding that has not had any radio access holes cut out, this job is left to the builder. The outer nosecone is a sturdy moulding that fits very well. Another pleasing feature was the use of the aluminium pushrods - I dislike snakes - which were already in situ, complete with ball joint connectors for the V tail torque rods.

Next out of the box were the wing tips. The surface finish is absolutely superb, the trailing edges are very thin and completely straight, and the top hinged ailerons and their gap sealing wipers on the bottom are very neatly done. The control horn shroud is moulded into the back of the wing, rather than being part of the servo hatch cover and is very small; the model is designed to keep all of the linkages inside the wing.

The centre panel finish is also excellent and features the word 'Sting' across the centre. The flaps are bottom hinged, a feature I like as it allows for a large amount of deflection for crow braking. Again, a small control horn shroud is moulded into the back of the wing. The centre panel has a small amount of dihedral built into it in the same way as the Pike, again a feature I like as it reduces the amount of dihedral where the tips join on to the centre panel.

The torsional rigidity of the wing components is impressive to say the least and there is no sign of any give whatsoever; a rigid wing is a fast wing, in my opinion. Incorporated into the wing skin are indentations to take the servo covers, but the wing skin is intact and the holes for the servo wells have to be cut out prior to installing the servos. To compensate for this the holes in the wing roots for connecting up the aileron servos are already done and are very neatly finished.

Finally the V tail and the accessory pack. The V tail is another beautiful moulding, very light and rigid with a superb finish. It's a one-piece unit held in place by two M3 bolts. The torque rods are ready installed, complete with balljoints. The accessory pack features clevises, brass control horns, brass servo arm connectors, wing and V tail bolts and servo covers. A particularly nice touch is the spare carbon wing joiner and spare bolts. Also included are a couple of instruction sheets showing details of the wing servo installation and the recommended control surface movements. These sheets are in German but are reasonably straightforward and easy to follow.

The first important job is the initial assembly of the model to see what it looks like put together. The V tail was fitted to the fuselage, the ailerons and flaps taped in place and the wing put together and bolted on to the fuselage. The model really is pretty; sexy curved leading edges to the outer panels complete with the rather cute upturned wing tips. The V tail also features very racy tips.

That initial assembly showed up a several points. Firstly the good ones; the join between the wing panels is excellent, very crisp with no gaps. The carbon wing joiners fit perfectly, no sanding required at all and absolutely no slop. The only minor flaw is the countersinking for the bolts in the V tail not being very neat and the holes are oversized, although this does not seem to affect the structural integrity. One thing which subsequently has come to annoy me is the use of two different size bolts to hold the wing on, structurally this is fine but it means I have to carry two different size drivers to put the wing on - there's just no pleasing some people!

Assembly

I was going to call this section 'Building' but that's a bit strong for putting a moulded model together. I guess I'm a bit of a building snob, but with moulded models it really is just a case of fitting the servos and linkages. I have to confess that I enjoy installing the radio gear, it's the final part of the building programme and it turns all the bits of aeroplane on the workbench into a working model that's ready to go. Magic!

I intend to keep this section short as few people buy a model of this calibre on the basis of how easy it is to build; you only build it once, it's the flight performance that counts.

Fuselage

The fuselage is pretty straightforward. The inner nosecone has to be opened up so you can put the gear in it. Some time spent carefully working with a Dremel soon sees the job done. There is a recess for the V tail servos that has to opened up to suit the servos of your choice; the good news is that there is room for two 15 mm servos side by side, which gives you plenty of options in the mini servo range. A section of threaded rod is glued into the front of the pushrods to take the clevises and the V tails are ready to go.

There is plenty of room for the battery and receiver and you can fit almost anything you like; I fitted a 5 cell pack of 1250 mAh Sanyo's and a Multiplex Mini 9 receiver, which, contrary to its name, is quite chunky. The leads for the wing servos are nice and easy to install as they slide down between the ballast tubes and into the radio compartment without any undue fiddling.

Wing

The first thing to do is to open up the servo wells, another job for the Dremel. The instructions show Volz servos, but I chose to use a set of the new JR Digitals. The flap servos go in as per the instructions, the only problem being the quality of the brass fittings, which left a little to be desired. These were binned and some commercially available brass horns were fitted (1.20 each from Brian Anderson), balljoints were used on the servo arms instead of the brass items which again were disappointing, bearing in mind the quality of the model itself. A little work was required with the Dremel to open out the section of the flaps where the brass horns screw in and I finished off by epoxying the horns in position to make everything solid.

The instructions show the aileron servos installed with the horns inside the wing just clearing the inside of the top wing skin. My choice of servos did not make this a practical proposition so the aileron servos were installed in the same way as the flaps and the linkages were bent to compensate. There is a recess moulded into the centre section for the D plug; reach for the Dremel!

The ballast tubes each take 6 slugs, 38 mm long and up to 15.5 mm in diameter. I used chrome plated 15 mm copper tube from B & Q and some 15 mm plastic pipe, again from B & Q, to make spacers. Some thinner wall metal tubing would have resulted in heavier ballast but the chrome finished ballast slugs just look too good to ignore. My ballast weighs 900 grams rather than a kilo, but I doubt if this will be an issue.

First Flights

The model arrived on Tuesday and by late Saturday afternoon I was ready for the initial test flight. I have to confess that I did put a few hours in as the plan was to test fly it on Saturday so that I could take it along to the Winter League F3F event in Eastbourne the following Sunday.

The wind had been a steady northerly for most of the day so I headed for my local slope at Watership Down with high hopes. Unfortunately I got there quite late and the wind had started to die down a bit, but there was still enough lift to get that all-important first flight in. The CG was on the front end of the recommended range and the settings were more or less as laid down in the instructions. I don't worry too much about other people's settings, as it is all a matter of taste. One man's twitchy model is completely unresponsive to someone else and vice versa. The settings to take note of are the amount of differential, the flap settings and the crow settings.

Anyway, back to the plot. As there was no one else about I had to launch the plane myself; a run and gentle push got the Sting away without any drama. It flew straight and true with no trim changes required. The lift was quite light, so it was a question of staying close to the edge of the slope in order to gain any height to play with. A few loops and rolls were done once a bit of height was gained and then a bit more cruising to get high enough to start a few fast passes in front of the slope. The model is certainly quick and has a fast cruising speed, thermal flap slows it up a bit but more height was gained by keeping it moving rather than by simply stooging around using flap.

The crow settings were tried out in front of the slope and they seemed spot on. The first landing approach was done slightly high to test the model's manoeuvrability in a real landing approach. As this went without a hitch it was followed by a landing for real. The Sting stopped virtually at my feet, well as close to my feet as I ever get! First flight done without any mishaps, always a good start.

It was at this stage that the plans for the review went wrong. The intention was to fly a few F3F competitions and put the plane through its paces to get a true picture of its abilities for the review. I therefore rang our illustrious editor to inform him that I would be campaigning the Sting at the following day's Winter League event in Eastbourne only to be told 'Haven't you heard? Tomorrow's been cancelled due to Foot & Mouth!' 'Oh Bother!' I said, or something very similar.

I managed to fly the Sting again the following day in slightly better conditions and that was that, no flying anywhere for months and months, and absolutely no sign of any F3F competitions for an even longer time.

A few months later and the pressure was mounting for a review of some description. Who says doing reviews is a cushy number? Plan B is hatched; do a 2 part review. This is part 1 and part 2 will be done after the plane has been flown in competition, at the time of writing the 2001 Welsh Open is being re-scheduled to the Isle of Wight. Sounds crazy but we F3F types are getting desperate!

So, back to flying the Sting. A few trips to Butser Hill later and I'm really starting to get a feel for it, and I have to say that I'm impressed! It's definitely very fast and the acceleration is absolutely outstanding! A gentle push on the elevator stick is all that's required to build up enough speed for aerobatics and it performs all the usual manoeuvres with considerable aplomb. With the reflex switched in it will hold inverted flight indefinitely and bunt almost as tightly as it loops. Square and triangular loops are a doddle and consecutive stall turns just get bigger and bigger; always a favourite with me. The roll response is very crisp and axial and hesitation rolls are not a problem.

How good is the Sting for F3F? Only flying it against the clock and other models will tell but so far it's looking good. I have flown quite a few practice runs with it and I'm confident enough to make it my number one competition model for the season, when we finally get some League events to fly in.

What I look for in a F3F model is acceleration and speed retention in the turns. Acceleration is already acknowledged so what about speed retention? Absolutely outstanding! With snapflap it really bites in the corners and keeping the speed up is no problem at all. A couple of times in the south-west bowl at Butser thermal lift came through while I was doing some F3F practice runs and the Sting went completely ballistic and just kept on building up speed turn after turn.

The only changes I have made to the set up so far is to move the CG back a bit and reduce the elevator throws slightly. I'm afraid I can't comment on ballast yet, Butser's not that good!

The Sting also soars extremely well in light air and thermals superbly. Karl Pashley and I recently flew her on an afternoon with very little slope lift and a few small thermals. We had no trouble keeping her in the air, even when the lighter loaded planes around us were struggling. The trick is to keep her moving and only use thermal flap when you are actually in a thermal. Sounds obvious but it's very tempting to leave the thermal setting in when struggling for height. Don't! Keep the model moving and look for the next bit of lift before dropping the flaps. It has a very fast, flat glide and covers a lot of sky when cruising.

Whilst on Butser's north-east slope the light was just right for photography so after a bit of fun gaining height and then showing off in front of the slope - we've all been there - Karl and I set about a few low, close passes for the benefit of camera. I was doing the David Bailey bit (my camera) and Karl was on the sticks. 'How about a low inverted pass?' I said. 'How low?' came the reply; the photo gives the answer. In fact the plane is on the way back up after the V tail clipped the heather!

Conclusions

A very impressive machine that I'm sure will prove extremely competitive for F3F. If you want a high-class sports model for slope use then you can't go wrong. It soars, it aerobats and it's very forgiving with no noticeable vices. The Sting is quality.

 

Specifications

Airfoil: HN1038

Tail: HN273 mod

Span: 2800 mm

Weight: 2400 - 3300 g

See the 3-View here

Price UK From 525

Price US From $795

QFI Ratings

(marked out of 10)

Speed of construction 9

Ease of construction         8

Flying in general         10

Flying (intended purpose) 9

Ease of ownership         9

Value for money                 8

Overall                     89%

Available in the UK from Soarhigh Models, 6a The Square, Turriff, Aberdeenshire, Scotland, AB53 4AH. Tel. 01888 560446 or e-mail guy@soarhigh.co.uk

Available in the USA from Composite Specialities, 2195 Canyon Dr #D, Costa Mesa, CA 92627, USA 949-645-7032. tom@f3x.com http://www.f3x.com