I see a lot of references to adding extra weight to the wing opposite a horizontally mounted engine to get the plane to balance.
I have never seen a reference of anyone correcting for a vertical or horizontally mounted engine. I would think that the engine weather mounted horizontal or vertical would still exert the same imbalance around the plane center line.
Is this correct?
I am debating between horizontal or vertical mounting the engine in my VF 300S 66".

Thanks in advance,
Greg

well if the muffler comes out the side of the engine that side will be heaver than the side with no muffler hanging out. i always mount the engine that way the plane is designed to be mounted and go from there. looks better if the whole engine can be hidden in the cowl

Hi prop hanger, is your engine a 4S or 2S? if 4 stroke, mount inverted with no probs at all as it doesn't flood, I prefer a 2S to be on its side or upright for the flooding reasons. As for lateral imbalance, side mounted engines make a very slight imbalance but you should be doing a lateral balance anyway.

Vertically mounted engines induce the same torque moment on an aircraft just as a horizontally mounted engine does. The difference being that with a vertically mounted engine the balance weight would be added near the centerline of the fuselage opposite the direction of orientation or installation of the engine. In most cases pilots neglect the imbalance in a vertically mounted installation because it doesn't effect the roll axis trim in level flight. However I suppose that this imbalance in the vertical installation could have effects in knife edge flight as well as other aspects that are less known to the majority of pilots (including myself). This is fresh in my mind because I read a post here where Quique Somenzini had refered to this condition. So my advice would be, if you are as skilled as Quique (not saying you aren't) then I would be worried about vertically balancing an engine. But for the other 95% of us I doubt we could tell the difference.

Happy flying,
Spencer

I'm definitely in the 95% that wouldn't know the difference.
I just thought that I would bring up the point and see what other people thought.

Greg

I would mount it whichever way reduces the cutout required in the nice cowl.. I put a Satio 91 sideways in a VF 58" extra with a pitts muffler and had to hack up the cowl way more than, in hindsight, I should have. With a fourstroke, mounting it down at 45-deg or so would also make the stock muffler come out the center of the bottom, eliminating the need for a pitts muffler.

-Greg

A 3/4 inverted (135 deg from upright) works nicely & puts the muffler directly underneath the engine. Both 2c & 4c engines work OK inverted. With a 2c inverted mount, correct tank height is somewhat important to reduce pre-start flooding & idle irregularities in some engines.

The plane that I am trying to decide on for the vertical or horizontal installation is the Vector Flight Extra 300S. I'll be installing the Saito 100 in it. I hadn't thought of a 135 degree installation. I'll have to see if that will work.

gnyberg...Where do you fly? I'm at MVRC.

Greg