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  #1  
Old 04-27-2017, 11:25 AM
Rocky005 Rocky005 is offline
 
Join Date: Jan 2013
Location: Perth, Western Australia
Posts: 34
Default RV-14 bottom cowl misalignment with air filter frame cover

Hi Guys
Our RV-14A bottom cowl has a misalignment with air filter frame cover and the bottom cowl air intake scoop is too low, this is causing issues with fitting the rubber seals. I have linked a photo of our issue and the other side not in the photo is the same (ie its symmetrical and not twisted).
Our cowls have been fitted as per the plans and the gap around the spinner is perfect.


It looks like a few other builds has this issue from photo's on their blogs but I have not seen a description of how they remade this area with a mix of cotton flox with epoxy resin. Anyone also have this issue and please share a few photo's of your repair?

Last edited by Rocky005 : 04-27-2017 at 11:28 AM.
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  #2  
Old 04-27-2017, 11:43 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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It is hard to tell since only a small amount of the spinner back plate/cowl interface is visible in your photo, but it looks to me like your cowl is a little lower than nominal.
This might be because the top cowl is not installed (this often lifts the lower cowl a bit)

As designed, following the plans exactly will result in a finished installation that has the cowl a tiny bit (maybe an 1/8") high relative to the inlet ramps. This misalignment disappears after the engine settles in and sags in engine mount vibration isolators.
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  #3  
Old 04-27-2017, 01:33 PM
SabreFlyr SabreFlyr is offline
 
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Location: Marion, IN
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Quote:
Originally Posted by rvbuilder2002 View Post
As designed, following the plans exactly will result in a finished installation that has the cowl a tiny bit (maybe an 1/8") high relative to the inlet ramps. This misalignment disappears after the engine settles in and sags in engine mount vibration isolators.
Scott, I'm FAR from this point of construction but I want to try to clarify what you're saying. It seems that you're saying the cowl will start around 1/8" high but that the difference will go away as the engine settles on the mounts. If the first part of your statement is correct, the problem would get worse.
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  #4  
Old 04-27-2017, 01:47 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by SabreFlyr View Post
Scott, I'm FAR from this point of construction but I want to try to clarify what you're saying. It seems that you're saying the cowl will start around 1/8" high but that the difference will go away as the engine settles on the mounts. If the first part of your statement is correct, the problem would get worse.
No, I said it looked like his cowl was a little low (I meant in the context of even more than intended).... and that would equate to the spinner being high.
If the instructions are followed, it will result in the cowl being purposefully mounted with the spinner about 1/8" high.
It looked to me like the one in the photo is probably closer to double that, but I could be totally wrong since not much of the spinner is shown in the photo....
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  #5  
Old 04-27-2017, 04:00 PM
Tom Martin Tom Martin is offline
 
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I have been working on the cowling this week. With the top cowling on my lower inlet matches the baffle quite well. The plans call for the use of two washers under a piece of angle that is cleoced to the top of the cowling. The angle rests on the spinner back plate and establishes the height of the cowling relative to the engine/prop.
Over many years and numerous aircraft I have not experienced a lot of engine sag with my rockets. I use the same isolators as the four cylinder engines and one would expect a bit more sag with a heavier six cylinder engine. After about 600 hundred hours on my current rocket I did raise the spinner by adding a large washer under the bottom engine mounts on both sides.
On the ground the engine is hanging from the engine mount. In the air the situation changes as the engine is now pulling forward. This raises the spinner and I do not like to see the spinner above the cowling in flight. We can set the spinner so that everything lines up properly on the ground and looks pretty but if we really want the alignment to be correct in the air then have the spinner a smidgen low on the ground relative to the cowling.
Keep in mind that I am always going for ultimate speed/efficiency rather then appearance. It takes a lot of time and money to get both!
Remember at the beginning I mentioned that the plans called for two washers to be used for vertical alignment of the cowl vs spinner; well I used one washer as I wanted the cowling to be a bit higher. The difference is only 0.063 and would not explain the alignment issues of the original poster.
My advice would be to follow the plans meticulously if this is your first aircraft. The plans are beautifully done and my firewall forward time has been dramatically cut with the excellent firewall forward package. The baffles are easily the best I have ever worked on and time was measured in hours rather then days.
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  #6  
Old 04-27-2017, 04:11 PM
rvbuilder2002 rvbuilder2002 is offline
 
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If working to that level of detail Tom you should be concentrating on shimming to the right.
From my experience P-factor pull causes a lot more lateral displacement than vertical.
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  #7  
Old 04-27-2017, 04:31 PM
Tom Martin Tom Martin is offline
 
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To the original poster. Following the plans has you eventually making an inlet change in the lower corners of the bottom cowling either side of your picture. There is a bit of measurement involved, a template provided, filling, sanding etc. In your case I would just cut back the bottom inlet an inch or so and pour a new one that perfectly matches the baffle surface and the corners at the same time. It will not be a lot more work then changing the corners.
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EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
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Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com
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  #8  
Old 04-27-2017, 05:12 PM
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jeffw@sc47 jeffw@sc47 is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
If working to that level of detail Tom you should be concentrating on shimming to the right.
From my experience P-factor pull causes a lot more lateral displacement than vertical.
Scott, wouldn't P-factor be most pronounced during climb. In S&L flight P-factor would be very small, if any at all, affecting engine/airframe alignment?
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  #9  
Old 04-27-2017, 10:03 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by jeffw@sc47 View Post
Scott, wouldn't P-factor be most pronounced during climb. In S&L flight P-factor would be very small, if any at all, affecting engine/airframe alignment?
I was joking.... note the

A hard climb does produce a significant amount of lateral movement, but you are correct. P factor is not a factor in high speed level flight.
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  #10  
Old 04-30-2017, 03:44 AM
Dustyone Dustyone is offline
 
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Location: Brisbane,Austalia
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Default Front cowl mod

While helping Alan fit his cowls to his new RV14A ,we also experienced the low cowl /high engine problem.

No amount of jigging would allow the front cowl seal to transition to the front baffle assembly.

Our solution was to fab a thin piece of .063 to the shape of the lower cowl inlet and use 5 x #6 screws to secure it to the lower cowl.
Nutplates had to be fitted to the lower cowl and Micro was used to make the transition smooth. The rubber is attached to the .063 with Sika.

The cowl rubber now sits flat and firm against the front baffle.A nice benefit of this mod is that once removed ,lowering the cowl straight down for removal is a lot easier.

We followed the plans exactly,so I am not sure what we could of done differently.
I will say that the RV14 cowl/baffle install is substantially easier than the RV-10 and credit due to the Vans engineering team for making such a comprehensive kit.





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