What is F5K Thermal Soaring?

F5K is a soaring competition class that originated from a cross between 3 different thermal soaring classes: F3K, F5J and F3J. The common aspect, Thermal Soaring is strengthened as much as possible and the unique aspects of the classes are integrated. One of the most important aspects of all classes is Thermal Soaring: the hunt for thermals on which sailplanes can rise to great heights. A beautiful game between nature, technology and piloting skills ranging from reading the air to taking strategic decisions while carefully maneuvering the plane according to plan. The result of the flight is different every moment of the day and even the most experienced pilot continues be challenged to find the right spot on the field to push his model higher and higher up in the sky. 

One of the characteristics of the F3K competitions is the fact that different tasks have to be performed, mostly consisting of multiple targets to be flown, making it necessary to carefully plan and execute launching and landing multiple times. The starts are very short. The model will be launched within a few seconds. The field (often 100 x 100 meter) can be used for landing. The models have a wingspan of approximately 1.5 meters

In F5J competitions, the intention is to start your model as low as possible and then to fly until the end of the working time of 10 minutes. The models often have a wingspan of approximately 4 meters and there is a penalty start system that rewards a low start. You must land as close as possible to a predetermined landing spot. The further you land from the landing spot, the more points it will cost you.

In F3J competitions, the model is launched by towing or by means of a winch. The starting height is approximately 175 meters and the working time is just like with F5J 10 minutes. Landing is precision work. Just like F5J, a spot landing is required. With F3J, the deduction in case you land less close to the landing spot is more than with F5J. This makes a landing with corresponding timing an important aspect of this class.

The main features of F5K are:

– Split second launch

– Penalty and bonus starting height system

– Multiple Task Contest

– Tasks consisting of multiple target times to fly

– Start and landing area

The maximum motor time is 7, 8 or 9 seconds and a nominal launch height of 60, 70 or 80 meters is set, determined one day before the contest and depending on the wind strength. An altimeter is used to limit motor time and manage and measure the launch height.  The Altis Nano is currently the only accredited device for measuring flight parameters for scoring. Both the height and the motor time are programmed in this device. The pilot can choose to turn the motor off earlier and collect the bonus points at a lower altitude. He can choose to take more height, but this can lead to penalty points. The nominal starting height will be announced before the race.

The model is started in a 6-sided starting area, which is also used as a landing zone.

All these facets ensure a beautiful, dynamic chase for thermals in a strategic game of land and launch.

This is “F5K Thermal Soaring”