The Skorpion story is interesting but fairly
simple. Man designs and moulds plane for his own gratification because he’s
grumpy at waiting for a replacement part for his usual toy. Homegrown plane turns
out to be rather good. Everyone wants one. Production begins. Man is
perfectionist and production model gets better and better until everyone and his dog want
one. That man is Arthur Frenslich and that model is the Skorpion.
Options
Most manufacturers compromise and offer very little in the way of options but when you get
a plane designed and built by a competitor they normally can’t help themselves.
The Skorpion is available in many different versions depending on whether your main
goal is Dynamic Soaring, F3B, F3F or simply sport flying. You can also choose how
many degrees of dihedral you want in your wing joiner. All this is fantastic news
but can be bit confusing for the inexperienced, or at least it would be if Arthur and his
dealers weren’t more than happy to talk through what would suit you best.
The review model is actually the third of my four
Skorpions. Despite being used exclusively for F3F it has what most would consider an
F3B type construction, being relatively light and using the five degree dihedral wing
joiner. I’ll explain why in the flying report.
Kit
What you get for your money is a 2.9m, two piece AF7/AF8 sectioned wing, a very clever two
piece tail and a neat, well proportioned fuselage that holds all the bits together.
Ballast, control horns and nice wing wiring connectors are also included and there’s
the option of very professional protective wing bags, which I’d strongly recommend.
Quality is close to some of the very best and the
essentials of fit, finish, strength and seam lines are all well executed.
The two piece V tail is a real work of art. The
engineering of the ‘pull for up’ linkage is something big names have tried in
the past (the V tail Elita for instance) but no one has succeeded anywhere near as
impressively as this.
Assembly is pretty standard moulded model
fayre. I'll stick mainly to the Skorpion specific issues but will give a few general
hints and tips along the way, rather than assume everyone was born with the knowledge of
how to slot mouldies together.
Fuselage
As far as the fuselage goes there's very little to look out for. Servos up to 13mm
thick work well. Go for the fastest you can afford for the elevators. I’ve
used Volz Micro Maxx Speed and the remarkably effective (circa £25 each, ball raced,
metal geared, fast, powerful and digital) Sanwa 762 from www.smartmodel.org both to great effect.
Using 4 x AA cells in a diamond formation allows you
to get them right up the front. The new generation Eneloop cells from Sanyo are well
worth a look. Five cells will go, but you’ll have to work it out for yourself
as it’s not my thing.
The supplied wing to fuselage wiring connectors work
well. When soldering them note that there is more space to one side of the pins than
the other and solder on the side with the most room. I would strongly recommend not
using heatshrink but instead potting the solder connections in epoxy or hot melt glue.
I have done this for 15 years now and the plug wiring has always outlasted the
model, whereas those neat little bits of heat shrink can get very tatty, very quickly.
You might have to relieve the wing and fuselage
wiring connector holes slightly, but by and large they’ll slide right in. Use a
drop of CA to secure one side and then epoxy on the other so that you have time to line it
all up so that it’ll autolocate nicely when you slide the wings on. Unless you
have a particularly large car, it’s wise to use a release agent at the lining it all
up and curing stage. The silicone grease used for bicycle gears is a cheap and
effective release agent.
Where the wing wiring goes passed the joiner box use
a piece of 1/64’’ ply to wedge them out of the way of the joiner. Use a
dab of epoxy or hot melt to secure the ply – see photo.
Unscrewing the tow hook allows it to be removed
completely through the ballast tube for easier slope launches. Note though, I’ve
never tried to reinstall one, so don’t blame me if you need to call a gynaecologist
before you take up F3B.
There is a tube installed for the receiver aerial.
It’s your choice whether to use it or have the aerial exit the fuselage and
dangle in the breeze for maximum reception. Whatever you do, range check holding the
plane at several attitudes before committing to the sky. If you do exit the aerial
through the tow hook hole be sure to protect it with some fuel tubing or similar at the
point where it exits.
The wing incidence pegs are primarily set up for the
3 degree joiner, so if you are using the 5 degree joiner the fit may be a little tight.
If so, very carefully relieve the hole using a needle file but remember that you are
only changing the angle of the hole and not widening the whole thing.
Tail
Depending on how much elevator movement you need you may want to free up the hinge a
little; the same applies to the ailerons. Gain access by holding the elevator in the
down position and very lightly run a small, flat bladed screwdriver through the space
created by the open gap seal and along the hinge line. Take your time and use light
pressure checking the effectiveness regularly. When returning the surface to the
neutral position be careful that the gap seal doesn’t catch on the skin. If it
does catch, very lightly use fine wet and dry paper to relieve the gap seal until the risk
of fouling is removed.
Wing
The wing is a very straightforward. Face your fears and do the scary bit first. You’ll
need to Dremel through the top skin and trailing spar (see photo) to get the pushrod
through to the horns. This sounds a lot worse than it is. Just take your time,
do it in small increments and you’ll be fine.
Once done you need to cut and sand the shrouds
carefully to shape. Attach them by putting a few drops of CA onto a smooth
non-porous surface, such as glass, slide the bottom of the shroud through the CA and then
position it carefully on the top surface of the wing.
Using servos of up to 13mm thick on flaps and 11mm
thick on ailerons allows the linkages to operate completely internally until they exit for
the control horn. Volz Wing Maxx (aileron and flaps), Sanwa 762 (flaps), Futaba 3150
(flaps) and Futaba 3155 (ailerons) all work well.
To keep the linkage internal and make the most of the
torque and centring you should be using very short servo arms. These will still you
plenty of movement but you will need to remove some of the ‘keeper’ arm on the
clevis so it clears the plastic collar where the servo arm goes on to the servo shaft.
A Dremel with a grinding tool does the job in seconds, but remember to protect your
eyes. It’s also good housekeeping to remember to place ‘keeper’ side
of the clevis on the servo side so that the clevis can be easily removed without fouling
the case of the servo.
There’s a little more guidance on installing
wing servos that I wrote several years ago here www.knewt.com/planes/servo.htm
Finally, whilst the supplied servo covers work fine,
I always use clear covers that you can make or buy from Samba at www.f3j.com. It’s very reassuring to be able to
see what’s going on inside and gives early warning if a clevis is about to pop off.
Flying
I’m now on my fourth Skorpion and have flown them for almost two years in
competitions and sport flying on dozens of hills, across five countries; so it’s fair
to say this isn’t a quick round up of the first flight.
There are three things you should know about flying
the Skorpion. Firstly, it is an exceptionally fast plane – one of the fastest
out there for sure. Secondly, set up right, it handles beautifully, turning faster
than most. Thirdly, if you get the set up drastically wrong, or ask more than it is
prepared to give, it will bite you harder than most planes. The Skorpion is your
classic thoroughbred.
Lets deal with the final point first. I’d
definitely recommend using the 5 degree joiner and a light (glass or F3B) lay-up.
This gives you a package that will deliver all the speed the design has to offer
and by virtue of keeping weight away from the extremities it will also deliver robust
handling with an incredible turn performance.
F3F
Use the manufacturers recommended movements and CG. If you feel the need to
increase the amount of up elevator, move the CG back, or increase the snap flap, then do
it one small step at a time and judge the outcome not just on screaming high speed passes
but at slow speed as well. I won’t publish my settings here as they are on the
exuberant side and would not be a good starting place. If you are interested drop me
a line at knewt@knewt.com and I’ll be happy to
share all.
Ballasting with the Skorpion is a strange affair.
The design itself is so slippery that you need less ballast in any given situation
than most. That said, if you want to load it up, the Skorpion responds superbly and
has quite amazing energy retention. My approach to ballasting the Skorpion has
changed over the last 12 months and I’m probably flying with a third more ballast in
any given situation than I started off with. Whatever your preference, it’s
nice knowing that it you get it a few slugs wrong it is unlikely to be critical.
The one exception is where the wind is a bit cocked
off the hill, in which case you are best advised to carry as much ballast as possible to
push back through the into wind leg. Although even in these circumstances it’s
probably less critical than other models.
The Skorpion is equally uncritical of F3F flying
style. Whether big reversals or tight bank and yank turns are you thing, the
Skorpion is equally at home.
Aerobatics
Flying aerobatics with the Skorpion is a doddle. The standard repertoire is all
achieved with no fuss at all, irrespective of which wing joiner is used. Rolls
(fast, slow and multipoint), loops (round, square or triangular), stall turns, cuban
eights and figure Ms are all a stroll in the park. The Skorpion's natural energy
retention sees it easily through the more energy sapping stuff like rolling circles and 8
balls, even without ballast.
Using no more elevator throw than for anything else
it'll do the most incredible flicks followed by the flattest spins you could imagine
– make sure you leave a rotation more than usual to recover, trust me!
For general showing off, howling passes and absurd G
pulling the Skorpion scores ten out of ten.
Thermal
Perhaps surprisingly the Skorpion is a very capable thermal machine. Dropping a
little flap really ups the lift and she’s well behaved enough to stand her up on a
wing tip, especially when using the 5 degree joiner. Stooging about in mediocre
slope conditions the Skorpion is regularly the highest in the pack.
Turbulators
The designer is a keen proponent of turbulators on the outer half of each wing panel and
the underside of the tailplane. I’ve tried this and certainly at lighter wind
speeds they do seem to help get the plane ‘on step’ faster and provide a bit
more grip around the corners. They are simple enough to make and attach using
fishing line and diamond tape. Space is at a premium here but your distributor will
be able to provide you with full details.
Crow Braking
More good news. Providing you get plenty of down going flap, which is easy enough to
accomplish, you’ll achieve very slow descents that make for simple landing even where
a very positive approach is required. Indeed hand catching is also rendered
relatively straightforward.
Summary
The Skoprion is a good quality, comparatively cheap plane that offers truly exceptional
performance. However if you don’t already have a few mouldies under your belt
you must start with the provided settings and ease yourself in gently as she will flick if
you don’t treat her properly.
For me, the most telling factor is how the Skorpion
rates against other F3F planes. When set up correctly I have seen competition pilots
regularly place five or more places higher than they were doing with their previous plane.
Swap planes back and you’ll see the positions change again. I don’t
recall seeing that with any other plane, and it probably says all that’s needs to be
said…
However, how does it ultimately compare with the new
breed of F3F planes for the super rich; the Freestylers, Calderas and Radicals of this
world. Will you get sufficient return on twice the price of the bog standard glass
Skorpion that I used to lead the 2006 Viking Race up until to the final round? No, I
think not. Will that extra investment get you any advantage at all over the
Skorpion? No, not in my opinion; indeed the fear of pranging such an investment
probably has the opposite effect on many pilots.
UK price from www.t9hobbysport.com
Glass - £615
F3F - £680
DS lite - £700
F3B - £730
US dealer www.soaringusa.com
For dealers in other countries, pilot forums
and so on www.thuro.at
