FAI Aeromodelling Commission (CIAM)

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F5 - Electric Flight

The World Championship Classes in Electric Flight consist of F5B Glider and F5D Pylon Racing. The important element in both classes is the limitation of energy to slow down the aircraft, especially for safety reasons. The effect of power limiting is the prolonging of the battery life, which results in competitors having to combine efficient energy use with tactical and flying skills.

CLASS F5B - ELECTRIC POWERED MOTOR GLIDERS

This contest is a multi-task event for RC electric powered motor gliders of Distance and duration and Landing. These two tasks are executed in one uninterrupted flight.

Model Aircraft specifications:

  • Minimum weight without battery: 1’000 g
  • Minimum surface area: 26.66 dm 2
  • Type of battery: Lithium Polymer
  • Maximum number of only serial cells: 10
  • Minimum weight of battery pack: 450 g
  • Limitation of energy by an electronic limiter that stops the motor: max. 1’750 Watt-min

CLASS F5D - ELECTRIC POWERED PYLON RACING MODEL AIRCRAFT

 

This class is a racing event for electric model aircrafts only. The race consists of 10 laps around a triangle measuring 400 m in circumference. The best competitors fly their model aircraft over a distance of more than 4 km in just 70 seconds or less !

Model Aircraft specifications:

  • Minimum weight ready to fly: 1’000 g
  • Maximum surface loading: 65 g/dm2
  • Battery Type: Lithium Polymer
  • Minimum weight of battery pack: 200 g
  • Maximum weight of battery pack: 400 g
  • Limitation of energy by an electronic limiter that stops the motor: max. 1'000 Watt-min

Class F5J - Electric Powered Thermal Duration Gliders

 

In the F5J competition class, the aim is to fly a remote-controlled glider with an electric motor for 10 minutes (or 15 minutes in the final rounds) from as low a take-off altitude as possible and then aim for a spot landing.

During the rounds, scoring depends on:

  • Flight duration
  • Accuracy of landing (as close to the assigned landing spot as possible)
  • Flight start height (penalties deducted as altitude increases)

The running time of the motor is limited to a maximum of 30 seconds. The take-off altitude is measured by an electronic device (altimeter) named AMRT which is placed inside the model. The more quickly competitors decide to stop the motor, the fewer penalty points they will accumulate.  

Depending on weather conditions and the skills of the pilot, 10 minute flights are possible even at an altitude of less than 10m. 

The pilot's goal is to find and use even the smallest thermal activity, otherwise the specified flight duration of 10 minutes is very difficult to achieve.

F5J planes usually have a wingspan between 3.5 and 4m. They are mostly made of carbon fibre, which helps them conform to the flying weight which starts at 1,000 grams.  

Within just a few years, F5J has become one of the most popular FAI aeromodelling classes.