fly boy3 Posted October 3, 2017 Share Posted October 3, 2017 The term "thrust line"has always bothered me.!! Not to be confused with right thrust, or up and down thrust. If I built an OD i/c job for example, which say has a 5-6 inch vertical fire wall. The engine now has quite a choice of mounting position in the vertical plane ( no pun intended). In the past I have positioned the engine so the carb. is the correct height with the tank, with no problems at all. This brings me to another query, which do I position first, the engine or tank position so they both line up. Cheers. ps, as the plane flies well when the motor is positioned using TLAR method, can I assume the engine is correctly placed on so called thrust line ? Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted October 3, 2017 Share Posted October 3, 2017 Topic with a more complicated answer than i can give you, where to mount ? on my own O/D's for me where it blends in with the cowl best, generally room to move tank to best position or rotate engine to suit. Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted October 3, 2017 Author Share Posted October 3, 2017 Thanks John, not to worry, if the answer is more complicated then at my age I may not understand it anyway lol. I suppose the TLAR method should be ok for most of my type of sport models. Thanks Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted October 3, 2017 Share Posted October 3, 2017 Lots off highly respected forum members use TLAR. Quote Link to comment Share on other sites More sharing options...
TIM Shaw Posted October 4, 2017 Share Posted October 4, 2017 Thrust line is actually a very simple concept in toy aeroplanes, and is simply the line drawn the centre of the crankshaft down the length of the model in both horizontal and vertical sections. As such, you choose where it is going to be based on where you bolt your motor mount and any downthrust or sidethrust you want to include. It only starts to get complicated when you try to determine where it should be, compared to the drag centres. It may be possible in theory, but I wouldn't know where to start. So TLAR to start with, use that to fix your tank position. then downthrust, sidethrust and CG trimming once its up and flying..... Quote Link to comment Share on other sites More sharing options...
Don Fry Posted October 4, 2017 Share Posted October 4, 2017 Wot is TLAR. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted October 4, 2017 Share Posted October 4, 2017 Posted by Don Fry on 04/10/2017 12:01:06: Wot is TLAR. That looks all right. Quote Link to comment Share on other sites More sharing options...
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