Engine Offset
 

Mike,

I mounted my DA-100 in the 35% Extra 260 and I noticed that when you look at the plane from the front, the spinner is not centered in the cowl's opening. It is off to the left (as you are looking at it) by almost 1/2".

When I drilled the holes in the firewall, I found the middle of the firewall and measured 3/8" to the left. That measurement came out exactly on top of the factory scribed vertical line.

I reconfirmed that I centered the engine on the cross hairs on the firewall.

Finally, when you stand in front of the plane and try to line up the engine's shaft, the center of the turtle deck, and the fin, it confirms that the shaft is over too far.

Should I try to move the holes (redrill) in the firewall?

Thank you for your help. This will be the fourth one of your designs I have owned. I can hardly wait to fly it! If this plane flys half as good as it looks it will be my favorite!!!

P.S. After writing the above, I reread the 77 page thread on the FG site. Where guys posted front end pictures, you could see that their spinners were offset just like mine. So maybe it is something is off with the cowl.

If the engine is not positioned correctly left to right, what flight characteristics would I notice?

RE: Engine Offset
 

I pulled up my CAD drawings for the 260. The exact offset should be 10.22mm (.402") to the left of the centerline of the firewall. It is slightiy more than 3/8", but only .7mm, which isnt going to make any difference to the perfrmance of the model. Hard to imagine you can see that though.

How far off center is your spinner?

Also, remember this back face of the spinner should be on the centerline, so the front of the cone should point to the right side if its installed correctly.

RE: Engine Offset
 

If you look from the front, you will see that the spinner backplate is over to the left by about 1/2" so it is very noticable.

Should I redrill the firewall?

RE: Engine Offset
 

Yes, if the engine is off that amount. But it shouldnt be if its offset 3/8" on the firewall. Are you shure the cowl is mounted straight? There is some wiggle room with the cowl mounting method we use.

RE: Engine Offset
 

I will try to adjust the cowl.

I am certain I measured and marked the firewall correctly (the anal retentive engineer comes out in me). I rechecked that I centered the DA on the cross hairs. So I'm certain the engine is mounted as per instructions.

On the FG site, there is a 77 page thread on the 260. It takes a long time to go through, but I noticed that the majority of the front end pictures looked like mine does.