F5J is a man-on-man format with electric powered models that are fitted with a special altimeter/motor run timer. An F5J contest consists of 10-minute rounds in which all pilots participate.
Flight durations must be performed within the working time limits (i.e. 10 ) or a penalty will result. This means that pilots who launch at the very start of the working time and land closest to the end of the working time will have the highest duration scores.
In the F5J rules there is a height penalty based on “…the maximum altitude recorded from the moment the model leaves the launcher’s hand until 10 seconds after the motor is stopped.” This penalty deducts 0.5 points per meter for start heights up to 200 meters, and 3 points per meter for start heights above 200. e.g. a start height of 201 meters would incur a height penalty of 103 points.
After each flight the plane’s altimeter must be read and recorded by the scorekeeper.
In F5J if you overfly the working end time you lose all landing points. Overflying past 1 minute gets you a zero flight score.
Landing bonus points (50 maximum) are made by landing as close to a marked landing spot as possible. Note that no landing bonus will be awarded if the plane’s duration exceeds the working time
There a specified maximum motor run time of 30 seconds.
In F5J the higher you fly during the launch phase the greater you are penalized. So one of the bigger challenges (and source of extra points) of F5J is to try and find as low a thermal as possible before the launch time is over.