winchweight Posted January 3, 2009 Share Posted January 3, 2009 Ok, my Mohawk has a bit of a climb problem. Even with a huge battery up front I still have to trim it nose down to get level flight. It's not the cofg that's at fault, so I guess it's the motors thrust line. If I trim it out at 50% throttle to level flight, then open up the power, it climbs steeply. So I intend putting washers behind the motor mounts to adjust the TL, but do I need to put them behind the top of the mount (ie to point the TL towards the ground a little more), or the bottom?As I said I should know this... Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted January 3, 2009 Share Posted January 3, 2009 If the motor is mounted on the front of the model in the usual way they need to be at the top of the mount to point the motor down. This will tend to pull the nose of the model down and thus help with your climb problem. Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 3, 2009 Author Share Posted January 3, 2009 Thanks Bruce, the model is a twin and the motors are mounted one on each wing. Does that make a difference? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted January 3, 2009 Share Posted January 3, 2009 No - same principle - incidentally Its not wing incidence angle is it ? Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 3, 2009 Author Share Posted January 3, 2009 Don't think so, unless the kit is sigificantly wrong Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 3, 2009 Share Posted January 3, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 3, 2009 Author Share Posted January 3, 2009 I'll try the thrust line first, and if that doesn't work, then I'll pack the TE. Won't be easy to do though as the wing is mid mounted. Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 4, 2009 Share Posted January 4, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 4, 2009 Author Share Posted January 4, 2009 Thanks Eric, I'll have a look and let you know how I get on. Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 4, 2009 Share Posted January 4, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 5, 2009 Author Share Posted January 5, 2009 To begin with I have put a couple of washers behind the upper mounting bolts on the motor mounts to see if that makes any difference. It is easier than packing the wing as the wings are mid mounted on a carbon spar, bolted through the fuselage wall. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 5, 2009 Share Posted January 5, 2009 ShaunMy suggestion is to trim for a stable glide and then land, without re trimming, and have a look at the position of the elevators (before you switch off the rx!). They should be in line with the tail plane. If they are, fine, adding down thrust is going to help but If they are not, then you need to adjust the CofG or incidence as the engine thrust was out of the equation. Adding down thrust before you achieve stable flight with the elevators in anything but aerodynamic neutral is likely to make the trim very sensitive to the throttle position, however a gentle climb on opening the throttle is preferable to diving! I hope this helps. Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 5, 2009 Author Share Posted January 5, 2009 Thanks Simon, I'll give it a try. I've already added a small amount of downthrust, but it is a tiny amount as I was always going to do this incrementally. Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 5, 2009 Share Posted January 5, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
winchweight Posted January 5, 2009 Author Share Posted January 5, 2009 'Fraid so. Damn these modern building techniques! Quote Link to comment Share on other sites More sharing options...
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