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
