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  #1  
Old 06-14-2021, 07:24 AM
IowaRV9Dreamer's Avatar
IowaRV9Dreamer IowaRV9Dreamer is offline
 
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Location: Marion IA
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Default Why do the plans call for this bolt to be upside down?

This is the bolt that holds the Exit Air Attach Contraption, er Brackets to the firewall. It is supposed to be installed head down.

That seems odd to me, so I have mine with the head up.

Does anyone know why the plans show it upside down? All I can think is that it keep the AN365 nyloc nut out of the hot air flow, but I can't believe that would matter.
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Dave Gribble VAF #232
Building RV-9A N149DG (slider, IO-320, IFR)
Restored and Flying Beech Super III N3698Q
Marion IA

Struggling with fiberglass

There is no sport equal to that which aviators enjoy while being carried through the air on great white wings." Wilbur Wright, 1905
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  #2  
Old 06-14-2021, 08:15 AM
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Greg Arehart Greg Arehart is offline
 
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Default

I would have thought because it is difficult or impossible to insert the bolt from the top if the engine mount is in place, but obviously you have done that so must be some other reason.
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  #3  
Old 06-14-2021, 08:22 AM
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IowaRV9Dreamer IowaRV9Dreamer is offline
 
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Quote:
Originally Posted by Greg Arehart View Post
I would have thought because it is difficult or impossible to insert the bolt from the top if the engine mount is in place, but obviously you have done that so must be some other reason.
Yeah its super easy to install the aft bolt from the top... unlike the forward bolts which are darn near impossible to get the nuts on!
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Dave Gribble VAF #232
Building RV-9A N149DG (slider, IO-320, IFR)
Restored and Flying Beech Super III N3698Q
Marion IA

Struggling with fiberglass

There is no sport equal to that which aviators enjoy while being carried through the air on great white wings." Wilbur Wright, 1905
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  #4  
Old 06-15-2021, 07:38 AM
lr172 lr172 is offline
 
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The head creates less drag than the nut plus threaded portion. Not a flight safety issue, so no need to account for failure modes.
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  #5  
Old 06-15-2021, 07:41 AM
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IowaRV9Dreamer IowaRV9Dreamer is offline
 
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Quote:
Originally Posted by lr172 View Post
The head creates less drag than the nut plus threaded portion.
Thanks! I actually wondered about that, but didn't think it would be significant.. I'll flip it around and get another 0.0000001 knot haha!
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Dave Gribble VAF #232
Building RV-9A N149DG (slider, IO-320, IFR)
Restored and Flying Beech Super III N3698Q
Marion IA

Struggling with fiberglass

There is no sport equal to that which aviators enjoy while being carried through the air on great white wings." Wilbur Wright, 1905
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  #6  
Old 06-15-2021, 07:45 AM
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Quote:
Originally Posted by IowaRV9Dreamer View Post
Thanks! I actually wondered about that, but didn't think it would be significant.. I'll flip it around and get another 0.0000001 knot haha!
I doubt you will see that much improvement.
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  #7  
Old 06-15-2021, 09:14 AM
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Snowflake Snowflake is offline
 
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Quote:
Originally Posted by Mel View Post
I doubt you will see that much improvement.
Not without a 3D printed fairing for it, at least. Where's Steve?
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  #8  
Old 06-15-2021, 09:18 AM
PilotjohnS PilotjohnS is offline
 
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Default Every time

I think every time someone crawls under there to wipe it down or do work, they are going to be thankful that bolt is upside down. If it is put it in with the head on the top side, one might consider putting a cap on the threads that are sticking down. JMHO
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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  #9  
Old 06-15-2021, 02:08 PM
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plehrke plehrke is offline
 
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Quote:
Originally Posted by IowaRV9Dreamer View Post
This is the bolt that holds the Exit Air Attach Contraption, er Brackets to the firewall. It is supposed to be installed head down.

That seems odd to me, so I have mine with the head up.
Designer’s Discretion.
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  #10  
Old 06-16-2021, 04:56 PM
agent4573 agent4573 is offline
 
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Quote:
Originally Posted by plehrke View Post
Designer’s Discretion.

Best practice is to install bolt heads forward, up, or out. If you deviate from best practice there should be a reason for it.
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