Another question on side thrust / offset engine
 

I'm planing to use a ASP 160 Twin on a big bird. The manual shows how to mount a 120, single cylinder engine. As you may know the engine mounts is completely different from a 120 single cylinder to a ASP 160 Twin.
After going through the building manual I still wonder if in parallel with the down and side thrust (2-3 degrees), the engine mount should be placed offset so the center of the propeller (and engine axis) will be in the center of the engine cowling.
Or the engine mount can be placed right in the center of the firewall and the side and down thrust achieved by using some washers. In this case, when looking at the front of the plane the spinner will not be in the center of the engine cowling.

The plane is a Stinson Reliant.

Hope I managed to make my self clear with my not so good english.


Thank you,


George

RE: Another question on side thrust / offset engine
 

Position the engine so that when it has the proper side and down thrust the spinner will line up with the cowl. This means you will probably need to mount the engine up and to the left of center.

RE: Another question on side thrust / offset engine
 

Thank you ! Now I just have to calculate what should be the offset of the engine mount to obtain the 2-3 degrees of side and down thrust.

George

RE: Another question on side thrust / offset engine
 

Hold the fuselage so the firewall is pointing straight up (or have someone hold it for you).

Place the engine on the firewall.

Put the cowl on and line it up.

Line up the engine so the prop shaft is centered in the cowl.

Carefully remove the cowl so you don't disturb the engine placement.

Mark where the engine is and you're ready to drill.

RE: Another question on side thrust / offset engine
 

Minn,
You make that sound so easy. I have to say it drives me nuts... :D

This probably doesn't matter much for your model, but if you're putting in a larger engine that turns a larger prop than the model's designer chose, you may find you need a bit more right-thrust to get the same effect. I've run into this a few times.

Of course, this really only matters on aerobatic planes where the desire is to get a plane flying as close to "perfect" as possible. On scale planes, it's just "character" to need a bunch of rudder with elevator application and so on. :D.