Looks simple and safe enough. Should work well. Only thing I wonder about is how you get those 1/4" bolts through 7/32" holes? Must take a big hammer...

Bob Kelly
 
Doubts

I reckon it would take all the powdercoat off the landing gear leading to corrosion. And if it slips or spins just a little...it will rip out your brake lines. Not a good design in my opinion.
 
I'm afraid my instrinct is as above... You either need to "grip" the leg very tightly, and/or a slip is v bad news :eek: The slightest indent made into the gear leg is the start of a failure mode (as above, even just through the paint allowing a corrosion start point).

There is a vertical up force from the jack, turned through ~45 degreees. Apart from the above issue, this now pushes the leg "outboard", which might cause the jack to topple over?

We have used a scissor car jack with an AL adaptor under the base of the leg / axle, and has fittings onto the fairing bracket to try and avoid a slip. It is not ideal, and again, as you "lift" the gear leg moves outboard, so the initial positioning of thge jack needs to make some allowance. However, at least the vertical jack force is applied vertically to the leg/axle assembly, and over a much larger area.

Just an opinion which may have missed something in the design...

Andy & Ellie Hill
RV-8 G-HILZ
 
1. The tire moves up, not out. Less than 2" movement on the jack and the tire will come off.

2. There's flap tape on the gear leg. The paint isn't marred.

3. If the clamp is installed so it makes full contact with the notch on the jack pad, and the jack positioned under the notch, there is no twisting moment possible.

4. The tensile strength of two 1/4" grade 8 bolts is certainly up to more than supporting the weight on the jack, whatever the moment on the pad.

5. It works just fine!

Tony
 
Tony,

Good concept, only thing I would change would be to make the 'hole' in the block circular instead of 'square'. This allows greater clamping force and less chance of an indentation into the gear leg. As the gear leg tapers and gets larger in diameter as you go up, once the 'clamp' is tight, it is unlikely to move up. To resist turning around the leg, the more clamping area the better, so a circular hole is better. As the clamp is aluminum, I don't think it could indent or even scratch the gear leg anyway....FWIW....
 
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Captain Avgas said:
I reckon it would take all the powdercoat off the landing gear leading to corrosion. And if it slips or spins just a little...it will rip out your brake lines. Not a good design in my opinion.
Click to expand...

Van's sells a similar device, so how bad can it be????
 
Yukon said:
Van's sells a similar device, so how bad can it be????
Click to expand...

Aaaaah the beauty of the archives. It's just a shame more people do not avail themselves of this extremely valuable information source.

Go to thread:
http://www.vansairforce.com/community/showthread.php?t=18533&highlight=jack

In post #4 Jon Baker reports that he purchased the Vans jack device with the U-bolt and that "the first time I used it, the U-bolt slipped and ripped out the brake line".

As Einstein was reported to have said: "A device should be as simple as possible...but no simpler".
 
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Captain Avgas said:
Aaaaah the beauty of the archives. It's just a shame more people do not avail themselves of this extremely valuable information source.

Go to thread:
http://www.vansairforce.com/community/showthread.php?t=18533&highlight=jack

In post #4 Jon Baker reports that he purchased the Vans jack device with the U-bolt and that "the first time I used it, the U-bolt slipped and ripped out the brake line".

As Einstein was reported to have said: "A device should be as simple as possible...but no simpler".
Click to expand...

So what can we conclude from one problem, Captain Gas? I have the Van's jack point, and have used them several times with no problems.
 
Wing Jacks

Speaking of Jacks..... what do you guys think of these simple wing jacks that Dave P made himself....

Very simple, nice cost and they are stackable.

IMG_2687.jpg
 
Yukon said:
So what can we conclude from one problem, Captain Gas?
Click to expand...

Builders can draw their own conclusions. I personally have 2 requirements for a wheel jack. One is that it should be totally reliable (it just doesn't make sense to risk MAJOR damage to a plane by lifting it with an el cheapo dodgy device just to save a few dollars). The second requirement is that it should be light and compact so that it can be put in the baggage compartment for specific flights to remote areas.

There are a couple of wheel jacks on the market suitable for RVs that fulfil these requirements....but they are not super cheap. But it's like everything else in aviation...you get what you pay for.
 
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Captain Avgas said:
Builders can draw their own conclusions. I personally have 2 requirements for a wheel jack. One is that it should be totally reliable (it just doesn't make sense to risk MAJOR damage to a plane by lifting it with an el cheapo dodgy device just to save a few dollars).
Click to expand...

Most likely this qualifies as a "el cheapo dodgy device", but I just used it to replace two tubes. Anyone with a modicum of common sense could do likewise.

http://picasaweb.google.com/tonyboytoo/DirtSimpleAircraftJack/photo#5189221244890599266

Tony
 
KISS....

....still applies.
We've jacked ours and other RV's by the wing tie-downs with bolts inserted in the tiedowns, heads cut off. We use a bottle jack on a couple of concrete blocks and a 2 X 6 on top of them.......Fred Flintsone engineering.....no problems...no falls....no holed wings...this ain't rocket science guys!!

We're not jacking 747's here!

Regards,
 
I have the one made by Van's - problem with it is that the U-bolt will take the paint off in a heartbeat. I recently tried putting this device on one of my gear legs. Just pulling up on the angle bracket with my hand caused a chip of paint to come off the gear leg where the U-bolt contacts it. I think Tony's design will be much better, especially if done with the round hole as suggested by AllanC.
 
The Willies!

Tony Spicer said:
Seeing an aircraft on wing jacks gives me the willies. This doesn't:

http://picasaweb.google.com/tonyboytoo/DirtSimpleAircraftJack

Tony
Click to expand...
Ha-ha I hear you, I can relate to the jacking planes and the willies.

This is the one I like:
http://www.vansairforce.com/community/showthread.php?t=21087&highlight=jack
Pics: http://www.vansairforce.com/community/showpost.php?p=152042&postcount=6
Discription: http://www.rvtraining.com/html/handy_jack.html

Not sure of weight and size but could be a good travel jack. You could enlist the use of a common floor jack in a pinch. Many airport repair shops have wing jacks that are too tall even at min height.

What do you all think of this one: http://www.averytools.com/p-181-rv-jack-stand.aspx
Again not sure about weight, but could be a good travel jack with out the bottle jack. It looks weird but it works. I've seen one in action once. If you need to, you can drop the plane down on the axial with wood blocks.

Not to take anything away from the clamp/bottle jack design, the idea was shown in the RVator about 15 yrs ago. Personally this one gives me willies a little as well. Any thing that has little resistance to fwd/aft aircraft movement with out tilting or slipping off worries me a little. A good mod is bolt the bottle jack to a wood base.

The good side of the clamp/bottle jack is it light and cheap. The down side with long gear fairings, there's no room for the bracket. Also it needs to be installed and removed for jacking. It is nicer than the one van sells.

THOSE PICTURES OF THE FALCO MADE ME ILL. :eek: :( Man I feel bad for those guys. The picture of those jacks will hunt me. Ughaaa!

I always used an "official" commercial wing jack on a bolt in the tie down. Never loved it but it worked great and gave you unencumbered access to the wheel and brakes. The good part, a group of guys have a pair to share. Most wing jacks at airports are too tall for most RV's, especially shorter gear RV's. RV-3, RV-4 and RV-6. BTW you can buy those tall bottle jacks at Harbor freight on sale sometimes for cheap. With some steel angles and channels, welding and some bolts you can make your own aircraft wing jack cheap.

The bottle jacks on homemade pedestal give me the most willies, but Daryl Tolliver's wood monolith, death to many tree's, deal above is not bad. I'd use a few more bolts and washers to hold the bottle jack base down, but I'm a belt and suspenders kind of guy.

By the way jack escapades and screw ups by Pros is not unheard of. The original prototype B747 fell of jacks and punched a hole in the wing or wings in the 70's. They patched it and flew the plane for years as a test bed, if not still flying today. I know they tested the B777 engines on it. It sat at Boeing field for years.
 
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Brian,

In order for a round hole to have more clamping pressure than the four point contact of two V blocks, the hole diameter would have to be an exact match for the gear diameter and the clamp would have to go on in exactly the right spot. V blocks make it self-adjusting and self-aligning. With the jack centered on the block there is sufficient clamping pressure to keep it from twisting as is. As far as the clamp knocking off paint/powdercoat, it has yet to happen on my gearlegs. But that's most likely because I ran a strip of nylon reinforced packing tape top and bottom on the gear legs to keep the rough inner surface of the fiberglass gear fairings from grinding off the paint. Works for the jack clamps as well.

And as I said in an earlier post, I just used it to change two tubes. Absolutely no problems, Capt Avgas :)

Tony
 
Tony Spicer said:
...four point contact of two V blocks
Click to expand...
Ever heard of a "stress riser"?

There's a loooong list of bad places on an airplane for stress risers to form; landing gear legs are pretty close to the top of that list IMO.

No offense, but just because it's worked for you a couple times does NOT mean it's a good design.
 
As long as the blocks are used only when jacking and the blocks are made of a softer material than the legs (the blocks deform, not the legs), there should be no stress risers whatsoever with this design.

Tightening the blocks will make some stress in the legs, but once the blocks are removed, that stress is gone. And since the stress in the legs caused by the blocks have to be max 1/10 of the yield stress (aluminum against spring steel), there simply is no way the legs can be permanently damaged. It is very easy to make the blocks immune too rotation once the jack is in place (I guess the design include this)

Looks like a good design to me.
 
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