I am building the BH Ryan STA, I am fitting an ASP120 4 stroke motor and on the instructions it says to mount it 155mm from the fire wall to the back of the spinner but when i put the cowl next to the motor to make sure i have clearance the motor seems too far forward. The instructions show a petrol engine, does that make a difference to the measerments. How far back does the cowl go on the fuse, it seems to slide back about 30mm overlap. Can someone help me please. Andrew.

Is this the 120 ARTF ? If it is than according to the pdf instructions you are correct at 155 mm.
The PDF instructions are foggy with cowl placement. It refers to marks on the fuse that you made but now where in the instructions that I could find tells you to make marks on the fuse.
If your thrust washer is 155 mm from fire wall. Then I would mount the cowl with around 1/6 inch plus clearance to back of spinner. Pictures of that Ryan show a little gap between the cowl and the fuse.
If that is what you end up with then you are probably good.


Understand I don't own this plane. Just someone who went and read the instructions.
Hope this helps.

PDF instructions here ---> http://www2.ripmax.net/Item.aspx?ItemID=A-BH072A

Kevin

Thanks Kevin i had a look at ripmax and there is a space between the front of the fuse and the back of the cowl. I am sure it`s for air flow. I can continue the build. Thanks again. Andrew