David Davis Posted February 20, 2023 Share Posted February 20, 2023 Regular visiters to this site will know that I participate in a daft competition every year called La Coupe Des Barons or The Barons' Cup in English. It's an event for a three-channel French trainer which looks a little like a Great War monoplane. For those unfamiliar to the event I have attached a link to a video of the 2017 event at the end of this piece. I have become quite well known in the competition for being the only Englishman in the event and for campaigning a four stroke. Indeed, I give a prize to the leading fourstroke pilot every year. I have two Barons so that I have a model to fly in the event even if I crash one in practice! One is powered by a Thunder Tiger 54, the other by an OS 52. There are four flying rounds to the competition including a pylon race and Chasse Renard which involves chasing a trainer towing a crepe paper streamer and cutting it off with your propeller. In both of these rounds a bit of speed is useful. I have always run my four strokes on 10% nitro, Lasers excepted. Should I continue using 10% nitro or should I increase the nitro content to get a bit more performance from the engine? If so by how much? https://www.youtube.com/watch?v=vYlLvJC-MuE Quote Link to comment Share on other sites More sharing options...
Jon H Posted February 20, 2023 Share Posted February 20, 2023 You might find propeller tuning to offer greater gains. Master airscrew props are woeful, apc would offer better performance. Maybe try a few, 12x6, 11x7, maybe even 11x8? and see which gives the best speed. A great deal will depend on how draggy your model is so a prop giving theoretically higher pitch speed maybe be slower than a finer pitch prop giving higher trust. Quote Link to comment Share on other sites More sharing options...
David Davis Posted February 20, 2023 Author Share Posted February 20, 2023 Thank you Jon. I usually use APC props. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted February 20, 2023 Share Posted February 20, 2023 Shim the head, run 30% nitro. Works for YS. 😈 Quote Link to comment Share on other sites More sharing options...
J D 8 Posted February 20, 2023 Share Posted February 20, 2023 Boosting the nitro will make little difference with the engines you are using, 10% is plenty. And that is where you are used to running them. As Jon says try some different pitch/diameter props, engine makers usually list best size/pitch for aerobatics, speed ect. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted February 20, 2023 Share Posted February 20, 2023 nitro gives a bit more power, but essentially for us on 4 strokes it makes the main needle valve less twitchy, as it also does on 2 strokes. Quote Link to comment Share on other sites More sharing options...
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