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Upper cowling/spinner backplate

T

Timberwild

Member
Before I start trimming my cowl, I would appreciate some feedback on how this looks. I have the upper cowling in place on the forward fuselage top skin and behind the spinner, but the angle of the spinner shroud looks weird. I?ve checked to make sure no obstruction is holding up the aft edge of the cowl, only resting on the firewall/top skin. No trimming has been done to the front of the cowling. Any thoughts on whether this is right or not? Thanks.

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Is your engine installed?

I cant open the pictures, but the cowling is purposely made with a rather noticeable offset for thrust. The engine mount sets the engine in offset for torque compensation. The only way to get it all correct is with engine on and prop spacers ect. in place with the spinner. Do not make it too tight..you will never get cowlings on/off. i can give you pointers for the gear leg cut-outs also that need to be just so. Think about everything before cutting anything!
 
Cowling

Thanks, Bill. Yes the engine is installed. I have the correct spacer and the spinner backplate in place. The angle I?m worried about is from the side: the spinner opening is closer to the backplate on top than below. So it appears to be sitting too low in front.
 
big angle

This does look like a bit too much angle. From what I can see, your cowl needs to be a bit higher assuming you want a smooth line from the spinner to the cowl. Lots of moving parts here, so I can't give a lot of specific advice without seeing it in real life, but I agree with you that you want the distance from the back of the spinner to the cowl to be about the same all around. How you get there is very dependent on the other factors.

Hopefully someone that's smarter and more experienced than I am will chime in with some hints.
 
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Maybe check that your back plate is perfectly flat to begin with, from your pic it looks like you don't have bolts in all the holes to ensure it is mounted flat and firm. I made that mistake with mine and had a 3/16 gap become less when I mounted the propeller and did all the bolts up, I had to do some reworking to regain the gap.
If your pink cowl is anything like mine was (ex Van's) there will be some fitting, trimming and filling required.

Russell
 
I think you?ve got the cowl in the wrong position. It?s final position will be about 2.25 inches forward which will cause the front of the cowl to be raised up to meet the spinner. That will decrease the angle you see there. Mount the prop and rear spinner baffle and you?ll see what I mean.

Bevan
 
Bevan said:
I think you?ve got the cowl in the wrong position. It?s final position will be about 2.25 inches forward which will cause the front of the cowl to be raised up to meet the spinner. That will decrease the angle you see there. Mount the prop and rear spinner baffle and you?ll see what I mean.

Bevan
Click to expand...

Good point, this is most likely the main reason. My prop was previously fitted to an RV 4 and had/has the 4 inch spacer.

Russell
 
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