UnPossible

UnPossible

Well Known Member
Hey - I spent all day fabricating the mounting strips to attach my cowling with Skybolt fasteners. (See Pic below)

2ntir8w.jpg


When I had them clecoed onto the plane, I wanted to see how the cowling sits.... however, I can't seem to get the cowling down into place, with the clecos holding the mounting strips on.... However, I don't want to rivet these on yet, as I dont't want to rivet the top front skin on until the very end.

I figure that I'm missing some stupidly obviuos solution..... anyone that went before me have any suggestions?

Thanks,
Jason
 
I just know there was a totally obvious solution that I was missing...

Thanks for the extremely quick reply!

Jason
 
I would suggest riveting the top skin on with the mounting strips before doing any shims or drilling final large holes for fasteners. I had drilled the holes and put shims on part of the fastener locations before riveting mine. After doing the riveting the dimensions changed when things tightened up and I had to redo or remove most of the shims. If I was to do it again I would just cleco on the cowl until the very end.
 
IMG_5772.jpg


I took this photo to show my TruTrak engine data module. However, you can see that after I had my mounting strip fit and in position, I drilled an additional rivet hole and riveted the mounted strip to the flange that will attach the top skin. I left all the top skins holes untouched, and added a flush rivet to just hold the strip in place. This way I don't have to deal with the clecos.
 
pmccoy said:
I took this photo to show my TruTrak engine data module. However, you can see that after I had my mounting strip fit and in position, I drilled an additional rivet hole and riveted the mounted strip to the flange that will attach the top skin. I left all the top skins holes untouched, and added a flush rivet to just hold the strip in place. This way I don't have to deal with the clecos.
Click to expand...

Peter - I was wondering about doing this exact thing last night... glad to hear that someone else has forged ahead without any unforseen issues.....
 
Hijack Alert!

I'm also planning to use Skybolts and have to ask a quick question: is the trimming and shaping of the attach strip for weight savings alone or does it serve another function? I think I remember Scott Card mention it might be more trouble than it's worth and can make putting the upper cowling in place a slight hassle....
 
It will allow you to bend each tab individually so you can either "pull-in" the cowl or "push-out" the cowl so it will follow the general shape of the firewall. If it's all one piece, you get what you get. I have only seen one plane without the notches cut and the fit was pretty lousy.

Phil
 
UnPossible said:
Hey - I spent all day fabricating the mounting strips to attach my cowling with Skybolt fasteners. (See Pic below)

When I had them clecoed onto the plane, I wanted to see how the cowling sits.... however, I can't seem to get the cowling down into place, with the clecos holding the mounting strips on.... However, I don't want to rivet these on yet, as I dont't want to rivet the top front skin on until the very end.

I figure that I'm missing some stupidly obviuos solution..... anyone that went before me have any suggestions?

Thanks,
Jason
Click to expand...

There should be .020 shims between the mounting strips and the firewall lip - see drawing 45 (for the 9A).
 
If using a solid piece it has to be fluted to get the angle correct, if using the tap style, the tabs need to be bent down to the correct angle. The cowling angle is different than the flange at the firewall. 10 cowling's installed with cam locks and the cowling's all fit very nice once the angle is obtained to allow it to lay correctly. Only my experience, yours may be different. Larry
 
Fred,

I agree with LARCO and Phil. The fuselage is not a perfect cylinder at this point, so a flat piece of Al will not allow the cowl to fit flat. You need to bend the tabs to adjust the fit of the cowl.

greg
 
JohnInReno said:
There should be .020 shims between the mounting strips and the firewall lip - see drawing 45 (for the 9A).
Click to expand...


I'm not sure the shims are requires if using skybolts or camlocs instead of the traditional hinges... I don't remember reading about shims in the installation instructions.... please let me know if I am wrong
 
For what it's worth, I've not used shims on the top with the camlock install but do on the sides with the hinge install. The older poly cowlings were much thicker and some did require a shim on the top. If memory serves me correctly, it's been awhile. :) Larry
 
Thank you to all who responded. The need to adjust the tabs because the cowling begins to taper from the firewall toward the nose makes sense. I will do that as well.
 
Did anyone do anything to the fibreglass on the cowls to strengthen them to support the camlock "pin" fitment?
 
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Mark Bolton said:
Did anyone do anything to the fibreglass on the cowls to strengthen them to support the camlock "pin" fitment?
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Can if you want to. I added a few plies of glass tape mostly as a shim, but the additional thickness adds bearing strength at the grommet holes. Does it need more bearing strength? I dunno!

 
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