Welcome to Thermal Circle 5, in this edition we will take a detailed look at F5B competition, the multi task electric event that has two disciplines, the distance task and this event also has a duration task, prompting this edition. This column contains an overview of the main rules. The F5B competition models have an awesome amount of power and are capable of very high speeds. These models are difficult to fly because of the high speeds attained and the weight and high wingloading of the models. Some Australian modelers are using competition F5B models as hot-liners, because these models are extremely fast and have wing sections optimized for speed and also duration. Australian F3J world champion David Hobby achieved seventh place at an F5B world championship the highest place recorded by an Australian, in an F5B world championship. A group of Australian F5B competitors have also produced there own model , named Kompressor for F5B competition. This model is a competitive, molded F5B model and this group produced there own moulds and constructed this model in Australia and at the end of the Thermal Circle 5 is some information on 7 cell soaring competition, a popular event in Australia for electric soaring models.

An F5B model must have the following specifications. A minimum weight of 2000g, maximum battery weight of 1100g and maximum number of cells is 30 and the model is to have a maximum surface loading 75 g/dm2. The starting order of the event shall be decided and established with a random draw of competitors and for the following rounds the order is to be reversed. The distance course layout must have a base A and base B, 150 meters apart with sighting devices, and for landing the appropriate landing area is to be provided for.

For each flight the total score for duration and distance, and also landing is be added and the round winner will receive 1000 points for winning the round. All other competitors will be index scored against the 1000 points as in other soaring competitions. In the case of a tied event the pilot with the highest discard flight will be declared the winner.

Before launching a motor check must be completed, the launch will occur outside the course. The model aircraft must be launched by the competitor himself or a helper to begin the competition flight. The distance task must be completed within 200 seconds of the model being launched. The distance task must be occur with at least two motor runs and a maximum of ten. Motor starts and stops must be indicated to the timekeepers. The pilot must be advised when the model passes base A and base B allowing the pilot to keep track of the amount of distance laps that have been flown. After 200 seconds the duration task begins.

For duration the task must be completed in 600 seconds after the audible announcement of the end of the distance task. The pilot will decide how long and how often he will switch on the electric motor. The duration time keeper will start the duration clock every time the motor is switched off. The pilot is to announce every time the motor is started and stopped to the timekeeper. Flying over time, longer than 600 seconds, results in point deductions for every second flown longer than this time. If the competitor flys longer than 30 seconds over this time no landing bonus will be awarded. The event has to be held on a level terrain to not allow slope or wave soaring to occur. This is a common rule used in other soaring events.

This is an exciting event to watch. F5B models can attain 250kph+ speeds and are small in size with extremely high powered motors. Molded models can be purchased to compete in this event, and the MAAA holds an F5B event at the yearly Nationals; allowing an Australian champion in this class. The FAI and other regulatory groups hold F5B events in there countries and there is other F5B events for models running less batteries making this style of event more affordable. The F5B rules are constantly changing and with a new battery rule, lithium polymer cells can now be used in F5B. May F5B be thrive in Australia and hopefully we will see an Australian world champion in this class.

7 cell electric events are some of the most hotly contested soaring events in Australia. The competing models are affordable they us Nicad and Nimh cells, the battery packs are affordable and many people scratch build there aircraft and there are also many competitive models for sale. The maximum battery size is as the event is as the event is named, 7 cells. The model must have the following specifications. Maximum are of all surfaces must not exceed 150dm2, a maximum weight 5kg and maximum wing loading 75g/dm2 The modification of battery packs for weight advantage is not allowed. No telemetry is allowed, varios etc are not permitted. Each pilot is allowed two helpers.

This contest is for RC electric gliders and the event entails a duration flight and landing. The rules clearly state that two rounds must be flown for an even to count. The site where the event is held must have reasonably level terrain that does not allow for slope or wave soaring. Landing circles are to be provided for the landing task. The event is to be organized into heats to allow fair man on man competition and the heat winner will receive 1000 points. The rest of the pilots will be indexed score to the winner as in other soaring events. In the case of a tied event the discard round will count to decide the winner. Motor control must be tested before launch.

The duration task involves flying a flight of 5 minutes. The use of motor counts in the score, one of the main tasks is to run the motor as little as possible. Timekeepers will time the contesting pilot with stopwatches and flying longer than 300 seconds results in a deduction of one point per second from the duration score. The landing will be scored for accuracy.

In the case of intentional cheating the pilot can be disqualified. If the soaring aircraft loses any part in the heat time a zero score is to be the result for that heat. If the model is flown by anyone other than the pilot a zero score is awarded.

7 cell electric soaring allows for affordable electric competition. Many ARF models could be used in these events and be competitive. Good thermal skills are required to win these events and the yearly nationals allow for an Australian champion in this discipline. Chargers for these small battery packs are also not expensive. Overall an interesting style of competition that can be flown and won on a budget.

Hayden Daley October 2008.