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more wing jacks...

bill.hutchison

Well Known Member
My Dad has gotten into machining parts and stuff for his car projects. I'm in VA and he's down in FL, so when I bought an airplane he got kind of excited for me and has offered to make bits and pieces as I've needed them. I had shown him some of the wing-jack threads and designs and he decided to make me something nice for the shop.

The jack is the standard Harbor Freight flat-bottomed ram jack. The base is 3/4" plywood. He made the collar, mounts, legs and base brackets out of standard aluminum stock.

The sleeve on the top of the jack is a tapered piece of billet, and the wing jack "pad" is domed and fits nicely into the taper. It's a very solid structure.

He probably over-engineered the **** out of it, but he had fun making it for me and it's really, really cool, so I thought I'd share.
 

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My compliments, but

Very nice craftsmanship. Please utilize appropriately. The base(s) are quite narrow. It will take less than most would imagine to knock that over. One ill-timed gust when the hangar doors get opened, trying to free a stuck bolt, etc. could really stink. Put a slight side pressure on your v-stab and watch.

Your Dad rocks but you knew that.
 
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Very nice craftsmanship. Please utilize appropriately. The base(s) are quite narrow. It will take less than most would imagine to knock that over.
[/QUOOE]

That was my thought too. The base should be larger and the support arms at a wider angle. Other than that it's got a lot of promise.

-Marc
 
Mine are similar, minus the craftsmanship. I got this design from an older EAA blog I found online. These jacks worked very well for my AP/IA at my last condition inspection. Rather than the elegant machine work, I just slipped some 1.5" OD tubing over the ram and it captures a smoothed-off carriage bolt that's screwed into the tie-down. About $170 all-in.
 

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Wing jacks scare me. I know they are used safely all the time, but I've seen one too many airplanes that fell off and received serious damage. Just recently there was a Cirrus in the local paint/composite shop that had fallen off of its jacks resulting in holes punched in both wings, narrowly missing the spars.

With a wheel jack, the downside of dropping the airplane is much smaller.
 
Wing jacks scare me. I know they are used safely all the time, but I've seen one too many airplanes that fell off and received serious damage. Just recently there was a Cirrus in the local paint/composite shop that had fallen off of its jacks resulting in holes punched in both wings, narrowly missing the spars.

With a wheel jack, the downside of dropping the airplane is much smaller.

True but you can't use them for wheel fairing installation unfortunately. My plan is to make some bottle jack setups just like in the pics above but I'm also going to put a little custom table under the center section as a "just in case". Still not perfect but better.
 
Bill, great to have a Dad to do things like this!!

Generally there are two (three) engineering things about these jacks:
1. you must have a capturing pivot to minimize the bending moment on the thread in the hack point. 14 deg tilt without interference. A tail dragger is 12 deg just sitting.
2. the "braces" must be tightly connected to the jack tube or top. You are forming a triangle for strength. The jack is a structural member.
3. The jack should be securely fastened to the base or have vertical a rod(s) connected between the tube sleeve and the base

Assume you have 500 lb on that jack. It is extended to the contact point 3 feet from the floor. What is the max side load to unseat the jack? (assuming it is rigid)

Lets' assume the base is rigid, and an X shape. The X legs are 15" long. This means minimum arm is 10.6 inches. So, 500*10.6 = X*36 where X is the side force. X=147 lb You can compare your dimensions accordingly.

Last thing - you want the vertical loads going to the threaded jack point, so it should be threaded into your cup and not depend on any load to the skin.
 
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Good feedback, all. I'd already mentioned to him that the base needed to be a little larger. The good news is that the legs are long enough that they can ride the collar down a little more for a larger base. And the legs are simple to make so I could also make new ones if needed.

BillL - noted on the jack point loads and threading. Thanks....

-b
 
Mine are similar, minus the craftsmanship. I got this design from an older EAA blog I found online. These jacks worked very well for my AP/IA at my last condition inspection. Rather than the elegant machine work, I just slipped some 1.5" OD tubing over the ram and it captures a smoothed-off carriage bolt that's screwed into the tie-down. About $170 all-in.

Mine are similar to those. I use a rounded head grade 8 bolt through a large socket threaded into the tie down. The socket acts as a cup for the ram so it can’t slip.
 
Mine are similar to those. I use a rounded head grade 8 bolt through a large socket threaded into the tie down. The socket acts as a cup for the ram so it can’t slip.

Yep. The smooth/polished grade 8 bolt in the wing tie-down against the ram with poly insert captured by the steel tube provides the necessary freedom of angulation. For a tricycle gear, anyway.
 
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PM to Bill.H

Bill, I sent you a PM re what your Pop made for you.

My Dad has gotten into machining parts and stuff for his car projects. I'm in VA and he's down in FL, so when I bought an airplane he got kind of excited for me and has offered to make bits and pieces as I've needed them. I had shown him some of the wing-jack threads and designs and he decided to make me something nice for the shop.

The jack is the standard Harbor Freight flat-bottomed ram jack. The base is 3/4" plywood. He made the collar, mounts, legs and base brackets out of standard aluminum stock. . . . .
 
I used the air/hydraulic jack from harbor freight, dont think they sell it anymore though, I picked up 4 of them on clearance, 59 bucks each, man that air keeps my sanity, extends the complete ram in about 1 minute. Have about 50 bucks of 4" wide steel into the base, about 130 bucks into each jack. The steel conduit was 12 bucks for 10 feet, 26" pieces.
 

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Here's my version. I don't weld! Jack is Vevor 4 ton long ram (around $50 on Amazon). A piece of pipe JB-welded to the end of the ram captures the head of a carriage bolt threaded into the wing.
Stewart Willoughby, 6
 

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Here's my version. I don't weld! Jack is Vevor 4 ton long ram (around $50 on Amazon). A piece of pipe JB-welded to the end of the ram captures the head of a carriage bolt threaded into the wing.
Stewart Willoughby, 6

You have more faith in JB Weld than I do
 
Here's my version. I don't weld! Jack is Vevor 4 ton long ram (around $50 on Amazon). A piece of pipe JB-welded to the end of the ram captures the head of a carriage bolt threaded into the wing.
Stewart Willoughby, 6
The JB Weld is a good idea. Right now I just slip the tube stock over the ram and it works fine...nice and solid when lifting the plane. But JB-Welding it to the ram would keep it from coming detached when moving the jack around.
 
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