F5D Pylonracing By Stuart McFarlane
F5D, the pinnacle of electric pylon racing. These
models are beautiful fully molded airframes designed with one purpose in mind,
to fly fast which they do very well with times being in the low 60 second
bracket for 10 laps of the FAI pylon course. Just think about that for a moment,
that is a lap time of 6 seconds to complete a 400-metre lap, an average speed of
about 150mph!
In the past this class, like many other electric classes,
has been on the end of some bad press with regards to the amount of money and
battery handling knowledge that was required to be successful.
All of this is now a thing of the past and the class is now
the easiest of all in which to obtain truly competitive equipment, and keep it
running.
The rules for the airframes for this class are very simple,
a minimum weight of 1kg and a maximum wing loading of 65g dm2. The drive train
can be any electric motor, any speed controller and Lipo batteries up to 5S. A
noteworthy point is that the Lipo batteries were introduced as a solution to a
safety issue following problems with the latest versions of NiMhs exploding when
overstretched. 
With the introduction of the Lipo batteries came the most
controversial rule change ever introduced in to the class where we saw the
introduction of an energy limiter. This clever device limits the amount of
energy that you have available for a flight and its very introduction took away
any need to select batteries. The introduction of this device caused a few
people to leave the class but also attracted many newcomers who could see that
they were now able to compete on a level playing field.
The models as we mentioned earlier are fully molded and the
most common airframes are the Jibe1, Jibe 2, Demon, Excite and Avionic all of
which are built in Europe with the exception of the Avionic that is made in
Russia. Almost all of the airframes are built to order and that allows the
purchaser to choose a colour scheme to their liking. All of these airframes are
available for around the 350 euros.
The motors are all brushless turning a small 4.75” x
4.75” propeller at up to 43,000rpm and there are basically two ways in which
you c
an
obtain a competitive setup. Some competitors opt for the high current option
(typically in the region of 100Amps) by using a motor with a high rpm per volt (Kv)
that they would normally run on a 3S setup.
By far the most common setup, particularly in the UK, is to
run a lower current option by using a motor with a Kv of around 2600 running on
a 5S battery drawing about 50amps.
Suitable motors are available from nearly all of the major
manufacturers and at a variety of costs but it interesting to note that for £60
you can obtain the same motor that finished second at the 2006 World
Championships in Romania. A Mega 16/25/2. 
Speed controllers are also available from most major
manufacturers with Hacker, Kontroniks and Castle Creations being the most
popular for the high current setups whereas for the lower current setups many of
the cheaper controllers work very well.
The Tornado 80 amp controller available for approx £60
from Overlander was used to good effect by most of the competitors in the 2007
British nationals and is now my preferred choice for all of my models.
Experience dictates that any controller that is used must
be opto isolated.
Now to the exciting bit…………the flying.
With a model of this performance the first flights are
always approached with a little trepidation but at least with an electric pylon
racer you do have a throttle control, unlike some of the other classes. However,
just as with any other model you will have checked and double-checked
everything, in particular the balance point, and it is this careful preparation
that will save you from any surprises.
All flights start from a good hand launch and I must say
that the current breed of models, post 2004, are a singe to launch compared to
the heavily loaded small wing designs of previous years. 
Flying the models is very easy and they will, if set up
properly, groove nicely round the course with very little deviation. The secret
here is to set the model up on dual rates that will give you a level of safety
just in case things don’t go as planned and then, as you gain experience with
the model, you can set about reducing the control throws to a minimum. An
absolute essential if you are hoping to fly a smooth course.
Looking at the current design trends of F5d models, and recognizing
their similarity to many gliding designs, it should come as no surprise to learn
that when the power is turned off they transform from a racing machine into a
very efficient glider. For this reason the landing of these models is a non
event, as long as you have bled off all of the excess speed.
The pylon race season normally starts in April and
continues through to November with races being organized every month at RAF
Cottesmore with a three-day meeting being held at the British Nationals in
August.
If you think this is the class for you or you just want to
learn a bit more then why not contact me using the e-mail address listed below.
Author Stuart Mc Farlane stumcf@blueyonder.co.uk
F5D Association Secretary darron.rodrigues@tealbox.com
Overlander www.overlander.co.uk
Jibe 1 and 2 www.flybiwo.com
Demon www.composite-models.nl
Neumotors Limiters www.neumotors.com
BMPRA www.bmpra.co.uk
F5D Websites www.f5d.co.uk www.f5d.org