F3B is a code according to the Sporting Code of the Federation
Aeronautique Internationale (FAI)
F = Model Aeroplanes
3 = Radio Controlled
B = Sailplanes So F3B is the worldwide recognized class of radio
controlled modelsailplanes. Since 1979 world championships are
held in this class.
The F3B rules are in short:
3 Tasks:
A: 10 minute thermal flight with precision spot landing
B: 4 minutes distance flight over 150 m closed circuit
C: Speed flight over 4x150 m
All 3 tasks must be flown with the same model. Only the addition
of ballast is allowed or an aerodynamic change of the model when
applied by remote control, for instance in the form of camber
changing flaps.
Most current models have a combination of the aileron, camber
changing and brake functions spread out over four wing control
surfaces. This is possible with modern computer radio controls.
Most pilots use separate flap and trim settings for the different
tasks.
Every task begins with a launch with an electrical powered winch.
Hand-towing is also allowed but only practiced during severe back-wind
sitations when it is possible to outlaunch the winch by hand.
The normalised F3B winch consists of a 1.1 KW, 12V car starter
motor, with a line drum on the axis.
The winch is placed at the line were the models start and where
the pilots and coaches stay. Maximum 200 m away a turnaround pully
is fixed. The nylon monofilament starting line is thus 400 m long,
running from the winch towards the pully and back. A small drag-shute
must be attached to the end of the line to signal the release
of the model at the end of the start and allow a controlled winding
down of the line.
Task A: Duration A maximum of 10 pilots fly at the same
time. From the start signal every pilot has a 13 minute working
time to complete his flight. In this working time the pilot has
to fly exactly 10 minutes from release of the winch line. It is
allowed to relaunch the model; the last attempt counts. The flight
should be completed with a spot landing. The flying time is stopped
when the model comes to rest on the ground (or in a tree ) Points
will be deducted when the model flies shorter or longer than the
10 minutes and points will be deducted for every meter the model
is farther removed from the landing spot. This score, or the best
score in the group of pilots flying at the same time is converted
to 1000 points. The other pilots get a partial score. In general
it is necessary to find a region of air with thermal lift, or
at least to avoid sinking air to manage the 10 minutes. The best
pilots manage the time often within 2 seconds and are seldom more
than 1 meter from the spot.
Task B: Distance 4 to 6 pilots fly at the same time. After
the starting signal the pilots have 7 minutes working time to
fly as much laps as possible within a 4 minutes flying time. The
course is defined by two parallel planes at 150 m distance, equiped
with sighting devices. Each time the models pass the line (called
base A and base B) a signal is given to tell the pilot to turn.
It is allowed to relaunch the model; the last attempt counts.
The 4 minutes flying time starts each time the pilot starts the
task when base A is crossed in the direction of base B. The pilot
with the most laps in his group gets the 1000 points. Tactical
decisions are to be taken in this task about the time and place
were to fly the task. Control of flying speed and exact turns
are important. Distance is the most challenging task for the team
as a whole. The 1000 points may as well go to someone flying 8
laps or even 30 laps depending on the atmospherical circumstances
during the working time.
Task C: Speed The pilots fly one by one. Every pilot has
4 minutes working time to complete his flight. After the launch
the pilot must try to fly a 4 laps distance (4x150m) in the shortest
possible time. The fastest pilot gets the 1000 points.
The pattern flown is in general direct from the launch back to
the base A line. There is little time to gain extra height in
thermals as only one minute is allowed between the release from
the winchline and the starting of the task. Before entering the
speed course one has to dive to get the initial speed, after the
dive into the speed course the glide angle is smoothly levelled
out till at the end of the task the model flies almost horizontally
with decreasing speed. Just after the dive the speed is up to
180 km/h, at the end of the task the speed could still be 100
km/h. The task can be flown in around 20 seconds, the better pilots
fly under 20 seconds consecutively. The absolute best time flown
at a contest was 14.24 sec. by Espen Torp from Norway at the World
Championships 1997 (during World Air Games) in Turkey.In this
task the timing and efficient use of height are important as well
as adapting the wing loading to the atmospheric circumstances.
In order to fly not too much distance the model should be rolled
to the appropriate bank angle before the base line is crossed.
Experienced pilots will make the speed turns even before they
get the audio signal from the line judges, they just know they
will be over the base line only one or two metres. This task has
the biggest luck factor in the F3B contests because the pilots
fly one by one and the thermal lift circumstances change rapidly.
A Contest In F3B contests the three tasks together make
up a round. For each round the total score is compiled by adding
the partial scores of tasks A, B, and C. A contest consists of
several rounds; 2 or 3 rounds at small contests and at least 5
rounds at european or world championships. If more than 5 rounds
are flown, the lowest task-scores are cancelled to reduce the
factor of bad luck even more.
