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First of all, if you are new to F5B or indeed high power electric gliders (Hotliners) then don’t worry about the rules.

All you really need to know is that there are special events held for these type of airplanes in the UK and you really should consider going to at least one of them to check it out !!!

F5B is a multitask event for radio controlled electric gliders. The three tasks that have to be completed in one flight are Distance, Duration and Landing.

Distance: You have 200 seconds (3min and 20s) from the moment the model is launched to complete as many 150 meter ‘legs’ as possible. Each completed leg scores 10 points. You can use the motor to climb up to 10 times but all legs must be completed with the motor off.


Duration: At the end of the distance task you have to fly for a further 600 seconds (10 minutes). Each second airbourne scores 1 point but three points are deducted for every second of motor you use. You also lose a point for every second you fly in excess of the 10 minutes.

Landing: The flight ends when the model comes to rest on the ground. A landing bonus of 30 points is added if the nose of the model is within 5 metres of a pre-determined landing spot. 20 points are added if the nose is within 10 metres, and 10 points if it is within 15 metres.

When you eventually do want to win an F5B league event or even want to get a spot on the UK team your model and equipment will have to fit around the following rules as layed down by the CIAM and FAI.

  • Minimum model weight without battery will be 1000g.
  • Battery Type – any type of rechargeable cells with a maximum pack voltage of 42v.
  • Battery minimum weight is 400g.
  • Maximum energy to be used is 1750 W*min (logger required) – penalty of 1 point per 3 W*min over 1750.
  • Minimum surface area 26.66 dm2
  • Maximum surface loading 75g/dm2

More detailed rules can be found on the FAI website. You can also download the F5 sporting code in pdf format.

General Information on the Rules which are applied in the UK league – General Rules Information

FAI F5B – This class is run as per the FAI F5B rules with one local change. For scoring we drop 1 round after 3 rounds flown rather than after 4. The reason behind this is a reasonable number of events can just have 3 round flown due to poor weather conditions.

F5B Intermediate – This class is intended as ones first step into F5B. The aim  of the class is for people to learn the course and how everything works without having to chase the model around the sky. Once they are ready they can then move up to the FAI class.

The course and flying time are identical to F5B the idea being you don’t need to change too much to move up to the FAI class when you are ready. The ideal power for these rules is around 2 to 2.5kW. You are free to use telemetry as per the FAI rules (ie no GPS or similar device for locating the plane during flight).

The following are the changes to the FAI F5B rules for the intermediate class.
1. Power usage – Up to 1300Wmin limit using a logger (ideally) or by charging back into the battery after the flight. A recharge efficiency of 95% and 3.4V per cell will be used in the calculation to work out Wmin used. (http://www.f5b.co.uk/Utils/watt-minute_calculator.xls)
2. No limiter enabled so you are free to use more than 1300 wmins however there will be a penalty of 1 point per 3 wmins of extra power used.
3. Any glider style plane

Sample mAh recharge for the 1300 Wmin are as follows

  • 2S – 3350
  • 3S – 2220
  • 4S – 1670
  • 5S – 1340
  • 6S – 1120
  • 7S – 960
  • 8S – 840
  • 9S – 745
  • 10S – 670

There are generally unilogs and shunts available to borrow on the day. It would be best to let us know if you need one prior so we can check it will be available.

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General Rules Information for an Event

The details below apply to all the classes which are flying in the UK F5B ...