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  #31  
Old 03-01-2015, 03:05 PM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
Default what a bummer

anytime you have a bolt that is subject to bending, STOP and correct it. bolts are for tension and shear loads only. the threads will concentrate the stress approx 4X.
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all

Simplicity is the art in design.
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  #32  
Old 03-01-2015, 03:56 PM
Mike S's Avatar
Mike S Mike S is offline
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
Default

Quote:
Originally Posted by Jackm View Post
Mike.

Does Vans approve this as a lift point with wings on and fuel in tanks?
Dunno-----did not ask. This shot is when I was doing the wheel pants, and the only place I could think of.

Quote:
Originally Posted by David Paule View Post
Sure hope the wood doesn't split!

Dave
Me too

Quote:
Originally Posted by N427EF View Post
For this very reason I selected plywood.

Would be interesting to see what Van has to say about this method of lifting.
Yep, to both.

Quote:
Originally Posted by Sam Buchanan View Post
A better option than the 2x12 would be three layers of 3/4" plywood running perpendicular to each other. The ply stackup won't split.
Correct, I need to do that, just never even thought of it.

Quote:
Originally Posted by jimbo View Post
Mike S.....I see no angle braces for the cylinder jack. Is the base of the
Jack welded to the bottom steel plate to prevent tipping over?

Jim
Yep, welded all the way around the base.
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Rv-10, N210LM.

Flying as of 12/4/2010

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  #33  
Old 03-01-2015, 04:52 PM
Jackm Jackm is offline
 
Join Date: Feb 2012
Location: Prosser,WA
Posts: 272
Default

Quote:
Originally Posted by rvbuilder2002 View Post
I also suggest that you ditch the pipe cap...

The tiedown points are more than strong enough to support an RV if you follow a couple of rules (think about it.... if they were designed to hold the airplane down with a lift force capable of lifting the weight of the airplane while it is tied down, then they are also capable of hold the same weight up)

The most important aspect is do not use a threaded pin (bolt) that protrudes out of the wing very far.
In our shop we use pins that use full engagement of all the threads that are typically on a course thread 3/8 bolt, and then only protrude about 5/8" max below the wing skin. Anything longer than this and the bending load on the bolt (and the lower end of the tie down anchor in the wing) begins to increase a lot, risking failure of the bolt.

Our shop jacks are made with the typical hyd. cyl. that is commonly used but instead of a cap on the top we have a piece of thick wall tubing who's ID closely matches the OD of the ram on the jack. It is slipped over the end of the ram and extends about 1/4 above it, to make a raised fence so the pin can not slide off. This gives a little bit of movement so the pin can move slightly if there is any binding during jacking.

BTW, I think the suggesting someone made of only jacking one side at a time is a bad one. Because of the flexibility of the gear legs, lifting just one point makes the airplane want to shift around a lot more. Doing a symmetrical, straight up lift is much safer in my opinion. If I am jacking solo, I switch back and forth between the two sides until I have the wheels clear of the floor.

20 years of jacking RV's this way I have never had any problem; though I have watched two improperly supervised aero engineers drop the prototype RV-6A on the top of an extended jack after lifting the airplane onto scales, so I guess anything is possible (no, Van wasn't one of them......)
If you jack the airplane with the 3/8 threaded bolt with cap or any sleeve mechanism..so the airplane is suspended with two 3/8 studs and weight on front wheel...add fuel in tank to create some slosh...then go to wing tip and give it a nudge (please don't do this) and watch the side load force on those studs. In my case I obviously was too aggressive and a idiot...but I will say it is recipe for outcome like ours.
What I like about this forum and why I posted this was....I have seen numerous posts of issues of others and wondered to myself " how in the world did he manage to do that" but it was a reminder not to do the same. We learn from others mistakes...at least I hope I do. In my case I must be number one to do this and I admit to being a Idiot ( I am so glad Bryan Douglass hasn't seen this cause he would confirm) but it can be prevented by coming up with a much more fail safe solution. Therefore our solution is this and I feel confident we will only fix one wing in my lifetime
https://www.dropbox.com/s/ninxmc4hb4...51050.jpg?dl=0
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  #34  
Old 03-01-2015, 05:16 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,947
Default Wing Jack

Thank you for starting the thread.
I've been following closely and hoping someone will post the perfect wing jack solution.
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Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
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Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #35  
Old 03-01-2015, 07:44 PM
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Ron RV8 Ron RV8 is offline
 
Join Date: Nov 2010
Location: Okanagan Valley BC, Canada
Posts: 483
Default For what it's worth...

Was at the hangar today so took a few photos...

These worked well for 18 yrs with the Mooney.

The -8 is higher so I'm considering adding some bracing for additional stability.

YMMV





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  #36  
Old 03-01-2015, 08:13 PM
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scrollF4 scrollF4 is offline
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Location: Flower Mound, TX
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Default

Ron,
What did you use to countersink the hole at the top of the jack piston?
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Last edited by scrollF4 : 03-01-2015 at 08:16 PM.
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  #37  
Old 03-01-2015, 08:13 PM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
Default jacking point

I use these with similar modified concave hydraulic jack ends as Ron_RV8 but I put an additional short vertical pin in the hole. I countersunk the hydraulic jack end slightly deeper into the modified concave to fit the pin. The vertical pin is LOOSE and only restricts lateral movement if for some reason the ball unseats. The lift load is on the ball not the pin. I made the pins from old drill stock. The ball end is $25 from Cleveland Tool. Less drag than the standard tie down ring and you can leave them in place.

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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all

Simplicity is the art in design.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 03-02-2015 at 03:16 PM.
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  #38  
Old 03-01-2015, 08:14 PM
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GLPalinkas GLPalinkas is offline
 
Join Date: Jan 2005
Location: Venice, Fl
Posts: 1,020
Default

Ok, let the comments begin. I want to know the downside of this technique... Our line guys at Venice use it when changing tires on the taxiways, etc.
Looks like a winner to me.

It rescued a friend of mine in an RV-8.

ps the foam block is dense material and will not crush under the weight of twins, etc (according to the line guys)

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Last edited by GLPalinkas : 03-01-2015 at 08:16 PM. Reason: sp
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  #39  
Old 03-01-2015, 08:54 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 5,516
Default

Gary, that looks good, but the only issue might be hydroforming the skin around the spar. You should look and see. It might be hard enough not to do that. Let us know if you see creases along the spar.

Load transfer is the most difficult issue in jacking a plane, getting loads to the heavy parts.
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RV-7
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and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
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  #40  
Old 03-01-2015, 11:16 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
Default

I put a hose clamp at the bottom end of my gear leg just above the bent. The hose clamp provide added grip for a floor jack to catch it a gear leg and lift it up. I do this only one side at the time but I believe it is a far easier and safer way to jack a RV
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