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Overtrimmed Cowl Top

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jeff(at)westcottpress.com
Guest

Posted: Thu May 09, 2013 11:23 am Post subject: Overtrimmed Cowl Top

It looks like I've over-trimmed my cowl top... this is where it currently falls with the 1/8" spacers between the face of the cowl and the back plate of the spinner and the spinner centered visually on the backplate. My choice at this point seems to be to either live with it, increase the space from the back plate and push it back a bit or raise the nose of the cowl up a bit which should also push it back (or some combination of the three options). The space you see in the picture, at its widest, is 1/16"



What say ye?



Jeff Carpenter

40304



sitting at the 90/90 phase

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dave.saylor.aircrafters(a
Guest

Posted: Thu May 09, 2013 11:32 am Post subject: Overtrimmed Cowl Top

The paint's gonna fill a little more of that than you might think, especially where it kind of wraps around the edge.  I'd be pretty happy with a fairly consistent 1/16 before paint.

  

Dave Saylor

831-750-0284 CL

 



On Thu, May 9, 2013 at 12:22 PM, Jeff Carpenter <jeff(at)westcottpress.com (jeff(at)westcottpress.com)> wrote:

[quote]  It looks like I've over-trimmed my cowl top... this is where it currently falls with the 1/8" spacers between the face of the cowl and the back plate of the spinner and the spinner centered visually on the backplate. My choice at this point seems to be to either live with it, increase the space from the back plate and push it back a bit or raise the nose of the cowl up a bit which should also push it back (or some combination of the three options). The space you see in the picture, at its widest, is 1/16"

   

 What say ye?

 

 Jeff Carpenter

 40304

 

 sitting at the 90/90 phase

 

 

 [b]

rleffler

Joined: 05 Nov 2006
Posts: 680

Posted: Thu May 09, 2013 12:14 pm Post subject: Overtrimmed Cowl Top

Like Dave mentioned, I think you're fine.  Paint will make that 1/8' gap

disappear.



--

_________________
Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler

schmoboy

Joined: 26 Feb 2006
Posts: 130

Posted: Thu May 09, 2013 12:29 pm Post subject: Overtrimmed Cowl Top

I made my cowl to fuse gap 1/16 all around.  Not painted yet, but assume 

the paint will fill some of that.



I made trimming mistakes on my cowl and easily fixed them using the 

methods outlines here: 

http://www.vansairforce.com/community/showthread.php?t=81595



-Sean #40303



On 5/9/13 2:22 PM, Jeff Carpenter wrote:

 	  Quote: 	
		   It looks like I've over-trimmed my cowl top... this is where it currently falls with the 1/8" spacers between the face of the cowl and the back plate of the spinner and the spinner centered visually on the backplate. My choice at this point seems to be to either live with it, increase the space from the back plate and push it back a bit or raise the nose of the cowl up a bit which should also push it back (or some combination of the three options). The space you see in the picture, at its widest, is 1/16"



 What say ye?



 Jeff Carpenter

 40304



 sitting at the 90/90 phase

aerosport1

Joined: 07 Nov 2007
Posts: 231

Posted: Thu May 09, 2013 12:49 pm Post subject: Overtrimmed Cowl Top

Jeff you can rebuild that pretty easy with some epoxy and chopped glass. 

Take some thin aluminum strip .03 about 1" wide. Wax the aluminum 2 times

Before putting on the cowl. Now slide it between the inside of the cowl and

the

Hinge. It should be a little tight just enough to hold in place. 

Then mix the 1/32" chopped glass with the epoxy. Make it like peanut butter 

or a little thicker. Then apply it. Let it cure overnight and sand it out.

I did this on one side of my cowl that I felt the gap was to large. No

problems



Hope this helps  

Geoff Combs 



--

_________________
Geoff Combs
RV-10 QB N829GW
Flying 500 hrs
40033

carl.froehlich(at)verizon
Guest

Posted: Thu May 09, 2013 12:59 pm Post subject: Overtrimmed Cowl Top

Do I understand correctly, you are setting up for a 1/8" space between the cowl and spinner?  If so, recommend at least 1/4" spinner to cowl gap.  This will also solve your cowl to firewall gap issue.



Remember that you also have leeway in the spacers you use to mount the spinner back plate to the prop.  Assuming you are using a Hartzell prop, your minimum (if memory serves me) is just using the 1/4" spacer.  You can add up to two 1/16" washers to this as well.  I used the 1/4" spacer and one washer so that when all was done and painted I could move the spinner back plate 1/16" closer or further from the cowl.  I ended up just leaving it as it was.

 

Carl



On May 9, 2013, at 3:57 PM, "Bob Leffler" <rv(at)thelefflers.com> wrote:



[quote] 

 

 Like Dave mentioned, I think you're fine.  Paint will make that 1/8' gap

 disappear.

 

 --

rv10free2fly(at)yahoo.com
Guest

Posted: Thu May 09, 2013 1:11 pm Post subject: Overtrimmed Cowl Top

Jeff,



You can also supplement what Geoff suggested using fibreglass tape, it works well, don't ask me how I found this out!



Warm regards



Patrick



On 10/05/2013, at 6:19 AM, "Geoff Combs" <g.combs(at)aerosportmodeling.com> wrote:



[quote] 

 

 Jeff you can rebuild that pretty easy with some epoxy and chopped glass. 

 Take some thin aluminum strip .03 about 1" wide. Wax the aluminum 2 times

 Before putting on the cowl. Now slide it between the inside of the cowl and

 the

 Hinge. It should be a little tight just enough to hold in place. 

 Then mix the 1/32" chopped glass with the epoxy. Make it like peanut butter 

 or a little thicker. Then apply it. Let it cure overnight and sand it out.

 I did this on one side of my cowl that I felt the gap was to large. No

 problems

 

 Hope this helps  

 

 

 Geoff Combs 

 

 --

carl.froehlich(at)verizon
Guest

Posted: Thu May 09, 2013 1:14 pm Post subject: Overtrimmed Cowl Top

Sorry - I meant to say a spinner to cowl spacing of 3/16" to 1/8".  I did 3/16" and it ended up a little tighter after prep and paint.

Carl

On May 9, 2013, at 4:59 PM, Carl Froehlich <carl.froehlich(at)verizon.net> wrote:

[quote] Do I understand correctly, you are setting up for a 1/8" space between the cowl and spinner?  If so, recommend at least 1/4" spinner to cowl gap.  This will also solve your cowl to firewall gap issue.

 Remember that you also have leeway in the spacers you use to mount the spinner back plate to the prop.  Assuming you are using a Hartzell prop, your minimum (if memory serves me) is just using the 1/4" spacer.  You can add up to two 1/16" washers to this as well.  I used the 1/4" spacer and one washer so that when all was done and painted I could move the spinner back plate 1/16" closer or further from the cowl.  I ended up just leaving it as it was.

 Carl

 On May 9, 2013, at 3:57 PM, "Bob Leffler" <rv(at)thelefflers.com> wrote:

> 

> 

> Like Dave mentioned, I think you're fine.  Paint will make that 1/8' gap

> disappear.

> 

> --

jeff(at)westcottpress.com
Guest

Posted: Thu May 09, 2013 2:01 pm Post subject: Overtrimmed Cowl Top

I'm working with the 1/8" spacers Vans specifies

On May 9, 2013, at 2:14 PM, Carl Froehlich wrote:



[quote] 

 

 Sorry - I meant to say a spinner to cowl spacing of 3/16" to 1/8".  I did 3/16" and it ended up a little tighter after prep and paint.

 

 Carl

 

 On May 9, 2013, at 4:59 PM, Carl Froehlich <carl.froehlich(at)verizon.net> wrote:

 

> Do I understand correctly, you are setting up for a 1/8" space between the cowl and spinner?  If so, recommend at least 1/4" spinner to cowl gap.  This will also solve your cowl to firewall gap issue.

> 

> Remember that you also have leeway in the spacers you use to mount the spinner back plate to the prop.  Assuming you are using a Hartzell prop, your minimum (if memory serves me) is just using the 1/4" spacer.  You can add up to two 1/16" washers to this as well.  I used the 1/4" spacer and one washer so that when all was done and painted I could move the spinner back plate 1/16" closer or further from the cowl.  I ended up just leaving it as it was.

> 

> Carl

> 

> On May 9, 2013, at 3:57 PM, "Bob Leffler" <rv(at)thelefflers.com> wrote:

> 

>> 

>> 

>> Like Dave mentioned, I think you're fine.  Paint will make that 1/8' gap

>> disappear.

>> 

>> --

rleffler

Joined: 05 Nov 2006
Posts: 680

Posted: Thu May 09, 2013 4:24 pm Post subject: Overtrimmed Cowl Top

I did a 1/8" on the spinner, but I should have done a 1/4".  I had to do quite a bit of work around the cowl due to not having enough clearance,



Sent from my iPad



On May 9, 2013, at 6:01 PM, Jeff Carpenter <jeff(at)westcottpress.com> wrote:



[quote] 

 

 I'm working with the 1/8" spacers Vans specifies

 

 

 On May 9, 2013, at 2:14 PM, Carl Froehlich wrote:

 

> 

> 

> Sorry - I meant to say a spinner to cowl spacing of 3/16" to 1/8".  I did 3/16" and it ended up a little tighter after prep and paint.

> 

> Carl

> 

> On May 9, 2013, at 4:59 PM, Carl Froehlich <carl.froehlich(at)verizon.net> wrote:

> 

>> Do I understand correctly, you are setting up for a 1/8" space between the cowl and spinner?  If so, recommend at least 1/4" spinner to cowl gap.  This will also solve your cowl to firewall gap issue.

>> 

>> Remember that you also have leeway in the spacers you use to mount the spinner back plate to the prop.  Assuming you are using a Hartzell prop, your minimum (if memory serves me) is just using the 1/4" spacer.  You can add up to two 1/16" washers to this as well.  I used the 1/4" spacer and one washer so that when all was done and painted I could move the spinner back plate 1/16" closer or further from the cowl.  I ended up just leaving it as it was.

>> 

>> Carl

>> 

>> On May 9, 2013, at 3:57 PM, "Bob Leffler" <rv(at)thelefflers.com> wrote:

>> 

>>> 

>>> 

>>> Like Dave mentioned, I think you're fine.  Paint will make that 1/8' gap

>>> disappear.

>>> 

>>> --

_________________
Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler

Lew Gallagher

Joined: 04 Jan 2008
Posts: 402
Location: Greenville , SC

Posted: Thu May 09, 2013 6:11 pm Post subject: Overtrimmed Cowl Top

Hey Jeff,



I have said before that in real life the gap between the spinner and the 

cowl can be at least 1/4" (as others have said here).  It keeps the spinner 

from getting into the cowl when the engine "shakes" on shut down, and makes 

it a bit easier to install the lower cowl without scraping its paint on the 

spinner.  I can't see that a tighter tolerance on that gap between spinner 

and cowl helps anything anyway.  I would have no second thoughts at all 

sliding the cowl back and sanding the high spots to make a tighter fit if 

your gap is 1/8 " or more at the firewall.  If you are painting several 

coats (i.e. base coat/clear coat), 1/16 may be about right.   If you want 

the "Swiss Watch" look and are doing 3 or less coats, maybe 1/32" gap.  I 

don't know any pilots personally that are dissatisfied with their   -10 if 

that gap is not perfect after flying more than 10 minutes        99/1 

phase?



Later, - Lew



--

_________________
non-pilot
crazy about building
NOW OFICIALLY BUILDER #40549
Fly off completed !

flying-nut(at)cfl.rr.com
Guest

Posted: Thu May 09, 2013 6:41 pm Post subject: Overtrimmed Cowl Top

The wider the gap between the spinner and cowl, the more cooling air 

escapes through that crack.  It can come from above the cylinders or 

below .... but that's a low pressure area and the air will find a way 

out.  But all is not lost.  You can use the foam pipe insulation, the 

size depending on the amount of space between the spinner backing plate 

and the front 'ring' of the cowl to seal that area.  Just split the foam 

down the seam and glue it to the cowl 'ring'.  The first time you start 

the engine the foam will become a 'clearance fit'. 

Linn



On 5/9/2013 10:11 PM, lewgall(at)charter.net wrote:

[quote] 



 Hey Jeff,



 I have said before that in real life the gap between the spinner and 

 the cowl can be at least 1/4" (as others have said here).  It keeps 

 the spinner from getting into the cowl when the engine "shakes" on 

 shut down, and makes it a bit easier to install the lower cowl without 

 scraping its paint on the spinner.  I can't see that a tighter 

 tolerance on that gap between spinner and cowl helps anything anyway.  

 I would have no second thoughts at all sliding the cowl back and 

 sanding the high spots to make a tighter fit if your gap is 1/8 " or 

 more at the firewall.  If you are painting several coats (i.e. base 

 coat/clear coat), 1/16 may be about right.   If you want the "Swiss 

 Watch" look and are doing 3 or less coats, maybe 1/32" gap.  I don't 

 know any pilots personally that are dissatisfied with their   -10 if 

 that gap is not perfect after flying more than 10 minutes        

 99/1 phase?



 Later, - Lew



 --

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Thu May 09, 2013 8:49 pm Post subject: Re: Overtrimmed Cowl Top

Leave 3/16"-1/4" gap. I built to 1/8" and it is too tight.

_________________
Wayne G.

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