Open scale rubber models are almost exact scale models, but they have to fly at least 15 seconds. And not only the flight duration is scored but also the flight realism!
Maximum weight (including motor): 150 g
Maximum wing loading: 15 g/dm²
There are no restrictions to the dimensions
View or download the F4D Rules (0.3 Mb pdf).
The judging rules used for the F4D scale class are the BMFA-rules, which are also used in the
Interscale and British Indoor Scale Nationals competitions.
Rules for all scale classes:
General scale rules [0.3 Mb]
Judges guide [0.3 Mb]