13-Apr-24 - 08:05 PM

Thermal Circle Text - Thermal Circle 39

Written by Hayden Daley - 18 February, 2022.

Welcome to this edition of the Thermal Circle in this edition the F3F slope racing rules from the FAI website and new products from Jeti, Spektrum and Multiplex many thanks to the Model Flight Company also known as OMP for the new products shown!!

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5. 8.1. Definition: This contest is a speed event for radio controlled slope gliders. A minimum of four rounds must be flown. The organiser shall run as many rounds as the conditions and time permits.

5.8.2. Characteristics of Radio Controlled Slope Gliders

Maximum surface area ..................................... 150 dm2

Maximum flying mass . ....................................... 5 kg

Loading .............................................................. less than 75 g/dm2

Minimum radius of fuselage nose


7.5 mm in all orientations (see template below). The radio shall be able to operate simultaneously with other equipment at the normally used spacing in the allocated R/C bands (i.e. 35 MHz : 10 kHz). 


The competitor may use three models in the contest. The competitor may combine the parts of the models between the rounds provided the resulting model used for flight conforms to the rules and that the parts have been checked before the start of the contest. Addition of ballast (which must be located internally in the model) and/or change of angles of setting are allowed. Variation of geometry or area is allowed only if it is actuated at distance by radio control. Any technological device used to aid in supplying data of the air’s condition or direct feedback of the model’s flight status is prohibited during the flight. These devices include any transmission or receiving devices not used to directly control the model aircraft (telephones, walkie-talkies, telemetry of airspeed and altitude etc), temperature detecting devices (thermal imaging cameras, thermometers etc), optical aids (such as binoculars, telescopes etc), and distance/altitude measuring devices (GPS, laser range finders etc). Telemetry of signal strength at the aircraft receiver and state of the receiver battery is permitted.

Use of corrective eyeglasses and sunglasses are permitted. I f an infringement of this rule occurs, the pilot will be disqualified from the contest.

5.8.3. Competitor and Helpers: The competitor must operate his radio equipment personally. Each competitor is permitted one helper. The helper is only to assist and advise the competitor until the model is passing Base A for the first time and after the timed flight is completed.

5.8.4. Definition of an Attempt: There is an attempt when the model has left the hands of the competitor or his helper.

  5.8.5. Number of Attempts: The competitor has one attempt on each flight. An attempt can be repeated if:

a) the launching attempt is impeded, hindered or aborted by circumstances beyond the control of the competitor, duly witnessed by the official judges;

  b) his model collides with another model in flight or other impediment and the competitor is not to blame on that account; cont/… Class F3F R/C Slope Soaring SC4_Vol_F3_Soaring_13 Effective 1st January 2013 Page 34

c) the flight was not judged by the fault of the judges.

d) the model (ie the fuselage nose) fails to pass above a horizontal plane, level with the starting area, within five seconds of exiting the course, due to circumstances beyond the control of the competitor, duly witnessed by the official judges. The re-flight shall happen as soon as possible considering the The re-flight shall happen as soon as possible considering the local conditions and the radio frequencies. If possible, the model aircraft can stay airborne and has to be brought to launching height, launching speed and launching position before the new 30 second period is started by the judge.

5.8.6. Cancellation of a Flight: A flight is official when an attempt is carried out, whatever result is obtained. A flight is official but gets a zero score if:

a) the competitor used a model not conforming to FAI rules;

b) the model loses any part while airborne;

c) the helper advises the competitor during the timed flight;

d) the model is controlled by anyone other than the competitor;

e) the flight is not carried through;

f) the model lands outside the assigned landing area;

g) the model is not launched within 30 seconds from the moment the starting order is given.

  h) any part of the model aircraft fails to pass above a horizontal plane, level with the starting area, within five seconds of exiting the course. 5.8.7. Organisation of Starts: The flights are to be performed round by round. The starting order is settled by draw in accordance with the radio frequencies used.

  The competitor is entitled to three minutes of preparation time from the moment he is called to the ready box. After the three minutes has elapsed, the starter may give the order to start. After the starter has given the order to start, the competitor or his helper is to launch the model within 30 seconds. The competitor or his helper is to launch the model by hand from the starting area indicated by the organiser. If possible, the starting area, including the audio system, shall be situated in the middle of the course (equal distance from Base A and Base B). The time from launch to the moment the model enters the speed course must not exceed thirty seconds. If the model has not entered the speed course (i.e. first crossing of Base A in the direction of Base B) within the thirty seconds, the flight time will commence the moment the thirty seconds expires. If the model has not entered the speed course within the thirty seconds, this is to be announced by the judges.


  5.8.8. The Flying Task: The flying task is to fly 10 legs on a closed speed course of 100 metres in the shortest possible time from the moment the model first crosses Base A in the direction of Base B. If some irremovable obstacle do not allow 100 metres the course may be shorter but not less then 80 metres. This exception does not apply for world or continental championships.

  5.8.9. The Speed Course: The speed course is laid out along the edge of the slope and is marked at both ends with two clearly visible flags. The organiser must ensure that the two turning planes are mutually parallel and perpendicular to the slope. Depending on the circumstances, the two planes are marked respectively Base A and Base B. Base A is the official starting plane. At Base A and Base B, an Official announces the passing of the model (ie any part of the model aircraft) with a sound signal when the model is flying out of the speed course. Furthermore, in the case of Base A, a signal announces the first time the model is crossing Base A in the direction of Base B.


5.8.10. Safety: The organiser must clearly mark a safety line representing a vertical plane which separates the speed course from the area where judges, other officials, competitors and spectators stay. Crossing the safety line by any part of the model aircraft during the measured flight will be penalised by 100 points subtracted from the sum after conversion, the penalty not being discarded with the result of the round. The organiser must appoint one judge to observe, using an optical sighting device, any crossing of the safety line. Class F3F R/C Slope Soaring SC4_Vol_F3_Soaring_13 Effective 1st January 2013 Page 35


5.8.11. Judging: The flights are judged by two judges who do not have to be the same for all competitors. The judges' task is to control that the flights are performed according to the rules, to be time keepers and to ensure that the right distance is flown.


5.8.12. Scoring: The result of the flight is stated as the time in seconds and hundredths of seconds obtained by each competitor. For the purpose of calculating the result of the round, the competitor's result is converted this way: 1000 x Pw P where Pw is the best result in the round and P is the competitor’s result


5.8.13. Classification: The sum of the competitor's round scores will determine his position in the final classification. If more than three rounds were flown the lowest round score of each competitor will be discarded and the others added to obtain the final score which will determine his position in the final classification. If more than fourteen rounds were flown, the two lowest round scores will be discarded. To avoid ties in the classification concerning the five best scores, "classification rounds" are flown until the ties are broken. If this is not possible, the result of the discarded round will determine each competitor's position in the final classification.


5.8.14. Organisation of the Contest: The competition must be held at a site which is suitable for slope soaring. When marking the starting and landing areas and the turning planes, the organiser must take into account the configuration of the terrain and the wind direction.

5.8.15. Changes: Any changes in the flight and landing areas may be made only between flight rounds.

5.8.16. Interruptions: A round in progress must temporarily be interrupted if:- a) the wind speed constantly is below 3 m/sec or more than 25 m/sec. b) the direction of the wind constantly deviates more than 45O from a line perpendicular to the main direction of the speed course. If these conditions arise during the flight the competitor is entitled to a re-flight. A round in progress is to be cancelled if:

a) the interruption lasts more than thirty minutes;

b) fewer than 50% of the competitors have been able to perform the task caused by marginal conditions. Without the condition "constantly" (i.e. 20 seconds) have been met and thus caused re-flight

Available from:

Multiplex Funray Electric


With the MULTIPLEX FUNRAY, a new era of ELAPOR® models begins!



  • Exceptional performance of a foam model
  • Extremely robust wings and sturdy height control system thanks to fully assembled plastic nose strips and aluminum-carbon fibre composite braces
  • Forcing the servo contacts with M6 high current plugs in the wings
  • Removable wings and helices
  • Removable side rudder with hollow hinges
  • Extremely stiff fuselage in M-Space technology and continuous carbon fibre reinforcement with 4-sided profile tube, GRP-straps and form fitting connections from the motor frame to the tailplane beam
  • Very performance-oriented Brushless drive set with 500 watts of power
  • Carbon fibre reinforced folding propellers
  • Very high-quality UV-resistant decor, finished applied, designed by Mirco Pecorari
  • Landing skid made of stable stone impact protection film
  • Trimming chamber in the rear
  • Very high performance, very precise flying through 6x Hitec Premium servos HS65HB with carbonite transmission
  • Unbreakable cab cover made of dyed material
  • All rudder flaps reinforced with stainless steel tubes
  • Spacious and tidy interior for battery and RC components

This fully-built, elegant 4-valve electric sailor inspires you with a dynamic sail flight. The FUNRAY has excellent all-rounder characteristics, on the slopes and in the thermals equally. After steep descent with Butterfly is a point-accurate landing a children's play.

The FUNRAY convinces with incredible speed and precision in the aerobatics. There was no such thing in the ELAPOR® sailplane models yet! This performance is made possible thanks to its modern hybrid construction in the composite of carbon fibre, stainless steel, aluminium, plastic and the special ELAPOR® construction foam.




Flight weight


Model characteristics





3 Advanced



RC functions

SR / HR / QR / spoiler / engine

Electric weight


Flight time


Total surface load per gdm


Total area in qdm


Types of cells / cells

3S LiPo

Construction time


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Jeti Central Box 210


The Central Box is a switchboard designed for the complete management of servos in a model with an emphasis on safety. 



  • Central Box 210 has unreduced power for each servo (without fuses)
  • Support of DITEX telemetry servos
  • Possibility to connect up to 3 receivers with serial interface
  • Built-in Expander function for up to 3 sensors
  • Input for a magnetic switch or RC switch
  • 2x MPX battery input connectors
  • 100Hz mode of servo outputs (10ms period)
  • Supports EX telemetry (voltage, current, capacity, temperature measurement, …)


The Central Box 210 offers maximal unreduced power for each servo (servo outputs do not have overload protection). The Central Box can manage up to two batteries and fully supports the JETI EX telemetry system. Up to three receivers with serial (PPM, EX Bus, S.BUS, UDI) output can be connected to the Central Box 210. With JETI DC/DS transmitter, the full potential of the Central Box can be used, such as an easy way to configure the Central Box, EX telemetry, and very fast servo response.



Weight [g]

65 g

Dimensions [mm]

66 x 42 x 18

Sustained current [A]

20 A

Number of channels




Operational temperature [°C]

-20 up to 85

Compatible protocols

EX Bus, PPM, S.Bus, UDI

Supply Voltage [V]

4 up to 8.4

Satellite receiver support


Batteries LiXX


Idle current [µA]


Number of battery inputs


Voltage stabilization


Available from:

Spektrum AR 8020T Receiver


The Spektrum™ AR8020T 8 Channel Receiver is a DSM2® and DSMX® capable receiver with a compact footprint to fit in a wide range of aircraft. It features full-range telemetry, integrated barometer to provide altitude and vario telemetry data without additional purchase.



  • Compatible with all Spektrum™ DSM2 and DSMX transmitters
  • Compact footprint fits most parkflyer size, sport class and giant scale models
  • Features full range telemetry, integrated barometer to provide altitude and vario telemetry data without the need of additional sensors
  • Bind button allows for easy binding and eliminates the use of bind plug
  • Two external antennas will ensure secure RF coverage from all angles of the aircraft
  • Additional RF path redundancy with an additional SRXL2 Remote Receiver (sold separately)
  • Ready to use with Spektrum Smart ESC for one-wire telemetry data without the need of modules, links and wires.
  • End pin output pins for easy and compact installation
  • Forward Programming capable for setting individual fail safe parameters per channel and more

Included XBUS and temperature ports can be used to add additional telemetry sensors available separately. It also features an SRXL2 port for an SRXL2 Remote Receiver, available separately, to add additional RF path redundancy. An SRXL2/Bind/Program/Batt servo header is available to connect smart devices, program and update the receiver, bind with a traditional bind plug, or connect a battery. The AR8020T also features a bind button for easy binding with no plugs necessary and offers both "SmartSafe" technology and Hold Last as well as preset failsafe types set through forward programming. Also, the throttle port is Smart ESC compatible right out of the box.


To enjoy the full benefits of Smart™ technology, use the AR8020T receiver with a Smart ESC and telemetry capable Spektrum DSMX® transmitter. Vital telemetry data such as current, voltage, temperature and RPM is sent directly to your transmitter in real-time. For more information on Smart Technology please visit our Spektrum Smart Technology page.


The Spektrum™ AR8020T receiver features an integrated barometer (built-in pressure sensor) to provide altitude and vario telemetry data without the need to purchase additional sensor modules.


Antenna Length

6.1" (155 mm)





Bind Method

Bind Button





Input Voltage

3.5 - 9V

Product Height

0.59" (15 mm)

Product Length

1.92" (49 mm)

Product Weight

0.56 oz (16 g)

Product Width

1.18" (30 mm)



Available from:

Spektrum™ AR20310T PowerSafe


The Spektrum™ AR20310T PowerSafe receiver is a feature-packed 20 channel receiver with integrated full-range telemetry. Each come with built-in connection ports for RPM, Flight Pack Voltage and Temperature sensors as well as an X-Bus port for additional telemetry options.



  • Binding is easier than ever by Binding through a button or familiar bind plug
  • Sensor port allows the receiver to be upgraded with future Spektrum add-ons
  • Compatible with all Spektrum DSM2 and DSMX transmitters
  • Rubber grommet hard mounts and minimalistic labeling helps produce the cleanest model setups
  • Capable of 11ms frame rates
  • Integrated telemetry with built-in ports for RPM, flight pack voltage, temperature sensors and X-bus for telemetry sensor expansion
  • Receiver pack energy & voltage sensor and flight log data available without the need for additional sensors
  • PowerSafe redundancy system with dual 13 AWG battery leads w/ EC3 connectors. Perfect for power hungry aircraft and high current applications
  • Not compatible with DSM2 AIRMOD JR Module (SPMMSJR720)

The Spektrum™ AR20310T PowerSafe receiver is a feature-packed 20 channel receiver with integrated full-range telemetry. Each come with built-in connection ports for RPM, Flight Pack Voltage and Temperature sensors as well as an X-Bus port for additional telemetry options.


If you have a DSMX®/DSM2® transmitter capable of 11ms frame rates, the AR20310T will deliver lightning-fast input-to-output response that is perfect for high-performance applications such as aggressive 3D , IMAC, and Turbine Airplanes. Each receiver includes 2 remote receivers that take advantage of Spektrum MultiLink™ technology. This patented technology eliminates the reflected signal fading and antenna blind spots that can affect all 2.4GHz systems.

A ground-breaking feature introduced on the AR20310T PowerSafe Receiver is the built in receiver battery energy sensors. Giving pilots added awareness of the load and mAh used by the servos, retracts, lights, etc. used by each battery. Current Gen 2 Radio firmware already supports this function. Also, as with most of the current receiver line up, these feature a bind button that gives pilots an easy alternative to the age old bind plug.



AR20310T 20 Channel PowerSafe Telemetry Receiver

# of Channels






Voltage Range


Experience Level



Thats all from the Thermal Circle Happy Safe and successful soaring. Hayden Daley 2022

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