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  #11  
Old 03-02-2017, 09:18 AM
Mudfly Mudfly is offline
 
Join Date: Dec 2011
Location: Alpharetta, Ga
Posts: 212
Default Dumb Idea?

I am preparing to install the wing ribs on my -14A project. Planning ahead for wiring and pitot line routing through the ribs brought me to the question as to where to place my pitot tube. I have read many threads on this subject and have a pretty good idea of pros and cons for the most used options.
My two preferred options:
(1)If I place the pitot in the plans location just inboard of tie down eyebolt, there will be no issue with tie-down ropes contacting the pitot tube. However, with this option it does make possible future maintenance of the connection fittings a little more difficult due to the aileron bellcrank assembly and torque tube locations. I know many builders have gone this route and had no problems.
(2)If I place the pitot just outboard of the tie down eyebolt, there are definite concerns with tie down ropes coming in contact with the pitot tube. However, it does appear to make for a "cleaner" install and future possible maintenance. The pitot line connecters would be easily accessible from the access panel for the aileron bellcrank assembly.

I don't have much light airplane flying experience so I'm not that familiar with the frequency in which the airplane actually gets tied down. Reading others posts, it appears some do not put the wing tie down eyebolts in place until they are actually needed.
Long story short, I prefer option 2, but don't like the tie down issue. So here's my dumb idea.
If I use tie down eyebolts that are approximately 4.5" long, that would, for most cases, allow the tie down rope to clear the pitot mast. Of course these eyebolts would only be installed when needed and removed prior to flight.
[IMG][/IMG]
This is a mockup of my preferred location. The rule with the blue tape simulates the tie down eyebolt. Here the bolt would be approximately 4.5"
[IMG]
[/IMG]
This shows the tie-down rope clearance when the ramp tie down point is approx. 7.5' from the wing eyebolt.
[IMG][/IMG]
[IMG][/IMG]
This measurement shows the distance of the pitot tube from the bottom surface of the wing. I would consider cutting my pitot mount off by 1" which would give additional clearance.
I wasn't sure the actual height of the wing bottom to the ramp, but after looking at pictures it appears to be about "thigh high" on most people. I used 34" for my setup.
Additionally, one issue that this setup may have is increased force on the tiedown bracket (riveted to spar web) due to the lengthened eyebolt. However, under those type of loads, would the bolt bend before damaging the bracket? That's for someone much smarter than me to figure out.
Practical or not? Don't worry about offending me
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  #12  
Old 03-02-2017, 09:52 AM
bret's Avatar
bret bret is offline
 
Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,828
Default

Quote:
Originally Posted by Toobuilder View Post
I have mine mounted ON the belcrank inspection plate both on the -8 and Rocket. No issues.
Hu.... me too.
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  #13  
Old 03-02-2017, 09:59 AM
Mel's Avatar
Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
Default

Quote:
Originally Posted by Mudfly View Post
I am preparing to install the wing ribs on my -14A project. Planning ahead for wiring and pitot line routing through the ribs brought me to the question as to where to place my pitot tube. I have read many threads on this subject and have a pretty good idea of pros and cons for the most used options.
My two preferred options:
(1)If I place the pitot in the plans location just inboard of tie down eyebolt, there will be no issue with tie-down ropes contacting the pitot tube. However, with this option it does make possible future maintenance of the connection fittings a little more difficult due to the aileron bellcrank assembly and torque tube locations. I know many builders have gone this route and had no problems.
(2)If I place the pitot just outboard of the tie down eyebolt, there are definite concerns with tie down ropes coming in contact with the pitot tube. However, it does appear to make for a "cleaner" install and future possible maintenance. The pitot line connecters would be easily accessible from the access panel for the aileron bellcrank assembly.

I don't have much light airplane flying experience so I'm not that familiar with the frequency in which the airplane actually gets tied down. Reading others posts, it appears some do not put the wing tie down eyebolts in place until they are actually needed.
Long story short, I prefer option 2, but don't like the tie down issue. So here's my dumb idea.
If I use tie down eyebolts that are approximately 4.5" long, that would, for most cases, allow the tie down rope to clear the pitot mast. Of course these eyebolts would only be installed when needed and removed prior to flight.

This measurement shows the distance of the pitot tube from the bottom surface of the wing. I would consider cutting my pitot mount off by 1" which would give additional clearance.
I wasn't sure the actual height of the wing bottom to the ramp, but after looking at pictures it appears to be about "thigh high" on most people. I used 34" for my setup.
Additionally, one issue that this setup may have is increased force on the tiedown bracket (riveted to spar web) due to the lengthened eyebolt. However, under those type of loads, would the bolt bend before damaging the bracket? That's for someone much smarter than me to figure out.
Practical or not? Don't worry about offending me
I would not be comfortable with a long tie down eyebolt. That would be quite weak IMO and would compromise the purpose of the tie down.
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Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
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RV-6 Flying since 1993 (sold)
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  #14  
Old 03-02-2017, 10:22 AM
runt runt is offline
 
Join Date: Feb 2016
Location: CA
Posts: 10
Default Removable tie downs

I think removing the tie down eyelets for each flight would be a PIA.

If you had a hangar and only flew local then you could leave them off but then again, if you had a hangar you wouldn't be lashing it down anyway so no interference issue in the first place.

However, an RV-14 is made to go somewhere so it will be tied down often. Murphy dictates that if they are removable, at some point they will be left behind.
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  #15  
Old 03-02-2017, 10:31 AM
Mel's Avatar
Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
Default

Quote:
Originally Posted by runt View Post
I think removing the tie down eyelets for each flight would be a PIA.
However, an RV-14 is made to go somewhere so it will be tied down often. Murphy dictates that if they are removable, at some point they will be left behind.
Mine have been removable for 24 years. It's just about as easy to unscrew them as to untie them. Haven't left them behind yet.
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Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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  #16  
Old 03-02-2017, 10:42 AM
RV7A Flyer's Avatar
RV7A Flyer RV7A Flyer is offline
 
Join Date: Jul 2013
Location: US
Posts: 2,251
Default

Quote:
Originally Posted by Mel View Post
Mine have been removable for 24 years. It's just about as easy to unscrew them as to untie them. Haven't left them behind yet.
Nowhere near as long, but same here...they live in my Bison Mountain flight bag behind the seat, along with my tiedown ropes and travel chocks.

I second the comment on the long tiedown idea above...sounds like something to bend.

Why not just put them where the plans have them (outboard of the pitot tube) and quit fussing with it? That location seems to work fine for everyone else, and there's zero chance of catching a rope or chain on the pitot tube.
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  #17  
Old 03-02-2017, 11:13 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,652
Default

Long eyebolts will bend with near certainty and possibly damage the wing in the process. I have bent some of the standard Vans eyes with the winds I get.

Mine also come out for every flight.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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  #18  
Old 03-02-2017, 12:03 PM
Raymo's Avatar
Raymo Raymo is offline
 
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,189
Default

Quote:
Originally Posted by Toobuilder View Post
I have mine mounted ON the bellcrank inspection plate both on the -8 and Rocket. No issues.
Ditto on my -7A.

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RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)

Last edited by Raymo : 03-02-2017 at 12:18 PM.
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  #19  
Old 03-02-2017, 02:03 PM
woxofswa woxofswa is offline
 
Join Date: Sep 2007
Location: Mesa Arizona
Posts: 608
Default

I had a judge at OSH ask me why I "put the Pitot in the wrong place". With my puzzled look he pointed out that mine was outboard of the access panel "where Vans intended in the plans". He then pointed out two -10's on the row behind me that sure enough had theirs inboard of mine. I told him that it worked fine and had great access from the end of the wing with the tip off.
Anyway, that bugged me and made me question myself if I had simply made an error in following the plans. The rest of the time at OSH I looked at every 10 I could find finally finding a couple that had it in the same place that I did, but we were certainly the minority.
When I got home I pulled out the instructions for the Gretz mount and they clearly advised to position the mount as far outboard as feasible which had obviously led me to put it where I did. Next time a judge asks, I can provide a confident and coherent answer.
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  #20  
Old 03-02-2017, 03:04 PM
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rzbill rzbill is offline
 
Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
Default

Mine is outboard from the belcrank bay, but on the outboard side of the next bay, unlike the mockup by the OP.

I have had no issue with tiedowns because the RV is so short that the tiedown ropes normally go forward from the eyebolt to the ground and pass the pitot with many inches of clearance.

Pitot Location
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Last edited by rzbill : 03-02-2017 at 03:07 PM.
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