Seagull Yak-3U Steadfast 20ccDescription Did you realise that 20cc is the new 10cc? Its true! In days of old . 60 size warbirds were the must have aeroplane for enthusiastic club modellers, however the introduction of the smaller petrol engine has changed all that. Meanwhile, swept in with the tide have been similar size powerplants (including the delightful 1. 20 four stroke glow and suitable electric set ups) and a raft of suitable ARTF kits of which this Yak 3U has to be one