what would be the effect of lowering the motor like a 1/4 to 1/2 on a yak54f foamie i was putting a new one on and just got to looking it would put it almost in line with the wing just above and just below the horizonal stab i think it is in line with the horizonal stab from factory.. thanks for any help i will wait to glue it in ..





______________
edited to make title more descriptive- bmatthews

In theory a lower thrust line will make the model want to pitch up a little more if everything else is the same. In reality any difference will be hidden by a very minor trim change and can be tuned by positioning your battery pack up or down to alter the 3 dimensional true CG. What the thrust line sits in line with or not isn't really an issue other than very slight effects that are only important to precision pattern flyers. Where the thrust line sits in relation to the true center of mass of the model is what counts.

I whack out various shapes of flat foamies - then go fly -all in a short space of time -
One interesting point -is in boldly increasing area of the fuselage - above or below the thrust line - with the thrust line remaining on the centerline of wing and stab. The models change how they respond in yawing - such as flat turns .
Also if you place the battery pack above or below - the yaw is again affected -
These small models really are a boon to those who want to see what is going on --first hand -rather than trying to apply info developed in wind tunnels etc., which may or may not be very relevant to a hobby aircraft.

thanks for the reply i have played alot with this type plane(yak54f) with new wing shape and size and control surfaces but never changed the thrust line but on what you said i will leave as is . is there a thrust line that would better it for 3d flyin is what i was looking for . I was thinking the same thing on pitch&trim but not sure with no relative wind and just prop wash over the surfaces .and flyin around in a stall but like I said Ill put it back like it was thanks again.....

Why whack out flat foamies of various shapes ?

I simply keep up-to-date with 'friend' Hanson's posts!

That's a compliment son-----!