Tie Down Info

[Abe]

Just thought I'd let the membership know about an article about tie downs in the July issue of Aviation Consumer and also on their on line magazine, avweb.com concerning our tie down systems. We spent quit abit of time last year testing our tie downs with our competition in Oregon and Idaho, but, as my wife said, it sure is nice to have an independent party put out some testing results also. Here is a link to the video on avweb.com http://www.avweb.com/avwebflash/exclusi ... 878-1.html

[n3833v]

The plates he pulled for the winner was pulled at a lower angle which made a big difference for angle pull. It depends on the soil as he mentioned and a person needs to pay attention how he ties down.

John

[jrenwick]

I've got a set of Abe's tie-downs that I bought in the auction at the 2009 convention in Duluth. I'll bring them to Oshkosh this year and use them, so that people can see what they're about. It's quite a different setup than what most of us are used to, bulkier and heavier than most, but it appears to engage much more earth than anything else of similar depth.

Here at Lake Elmo we did a similar test to the Avweb one, with an engine hoist and a scale, on a few tiedown types (not including Abe's, which I didn't have at the time). The kit I was using, which is three 12-inch spikes driven through a small steel fixture that spreads them and sets their angles at 120 degrees apart and 45 degrees to the surface, did very well, at about 400 pounds if I remember right. We probably have better soil than in the Avweb video. "The Claw" is very popular at Oshkosh, and I was puzzled and disappointed that Avweb didn't test that one in their comparison. (We didn't have that one either.)

I used to use the anchor with the split disk at the bottom of the stake that you screw into the ground, until one year at OSH when it rained quite a bit. With the soil that wet, I found I could pull the stake straight out of the ground with my hand. A big plug of dirt came out, leaving a very neat 3" diameter cylindrical hole. I'm all done with those!

[bagarre]

That was a slightly unfair comparison. I think all of them would have held somewhat better if pulled at such a shallow angle to the ground. It's more dirt to pull against.

A better way to compare would be to make a simple rig that put an eyebolt at the height of a typical high wing and the anchor at the typical position (six feet forward and three feet out) and pulled them all the same.

But, the idea of using spades instead of spikes makes SO much more sense in anything but the hardest ground. I wish I didn't get The Claw for Christmas last year.

[Abe]

In all fairness to Paul and his test on the avweb site, he had used his hoist and had maxed out his dynometer at 1000 lbs using the correct angle and that is when he hooked the pickup to the tiedowns. I agree that is was a bit confusing. In an earlier test video avweb compares the other tie down systems you mentioned and at that time they were not aware of ours. And as some of you know, last year we did some testing at seven different sites in Oregon and Idaho comparing our systems with the claw and the flytie and you can see those tests on our web site.

[GAHorn]

The "Claw" does seem to be popular although I have no attracton to it. It seems a simple matter that if one places the wind eyebolt directly above the Claw (as the design prefers).... then there is automatically lesser mechanical advantage to that type of device. Why? Because at most it merely grabs about one large bucketful of dirt which weighs about 150 lbs at most...so that is the maximum holding power available to it... while airplanes are capable of lifting a ton by design.

Any device which is used at an angle should have greater capacity, in my opinion, and Abe's design certainly enjoys greater advantage due to it's spade. (A harsher test might have been to pull against them with the truck pulling the rope over a saw-horse...but regardless, they clearly are a stronger design than mere spikes.)*

The other units do not have sufficient depth, although they use more spikes...they are too short, IMO.

The dog-tie/cork-screw types are simply too light-duty, although owners of those types like them and have anecdotes of how they cannot pull them out by-hand...(not necessarily a valid test, IMO.)

My own home-made tie downs are 36" spikes placed at angles to each other and I've enjoyed good success with them. Perhaps at a convention we should all bring our devices and agree to test them using more scientific methods.

IN any case...it doesn't work well to have a great tie down stake ...and use cheap, thin, or poly ropes rated at only a few hundred pounds. (1/2" or greater twisted or woven nylon is a minimum, IMO)

[Bruce Fenstermacher]

I took the pull test for what it was worth. In a few cases I saw the pulls were not exactly the way an airplane wing might pull it or the angle was not what the designer had in mind.

I am not a fan of the Claw because I've seen a few of the cast legs break in high wind conditions. I don't know if they were used as designed which as George points out is a straight up pull.

I don't agree that all a Claw type design is capable of holding is 150lbs. Yes if the ball of dirt is broken free from the surrounding dirt, it at best might weight 150 lbs, but breaking that ball free of it's surroundings is another story. At least here in PA it would be. Again the type of soil makes all the difference. George, you'd have a very hard time driving 36" spikes into rock and clay we call soil here in PA.

I made my own tie downs using the EAA design published in Vintage Aircraft : http://www.vintageaircraft.org/magazine ... iedown.pdf . I think George's tie down idea is similar. My spikes are just under 18" and they have worked well for me here in PA and last year in Michigan. But I can't say they've really been tested except maybe the storm a few years ago at Lock Haven, PA that broke the Claw and allowed a few aircraft to get blown around.

[jrenwick]

To be honest, the only time my tiedowns were ever really tested was 20 years ago with the J3 in a hail storm with winds that shot the hail horizontally through my new Stits cover job like bullets. I watched it try to blow my pride and joy into the next county, but the tiedowns held. They were the split-disk dog-stake type, one foot long. This is not an exact science!

[Abe]

John,

I have several other folks taking our tie downs to Oshkosh, I'd love to hear how they do for you. I'm hoping for real good weather for the event and not a repeat of Fun in the Sun. You are so right that it is not an exact science. Have a great time.

[wingnut]

Perhaps at a convention we should all bring our devices and agree to test them using more scientific methods.

I have to ask; Would this test involve Becks Dark?

[Bruce Fenstermacher]

Perhaps at a convention we should all bring our devices and agree to test them using more scientific methods.

I have to ask; Would this test involve Becks Dark?

Lets see now. Some kind of device capable of pulling at least 1000 lbs., a hammer of sufficient size to drive a stake 36" into the ground if we are testing George's system and a bunch of engineers who have different ideas how a system is suppose to work, might work better and then of course the best way to test it.

Hmmm, yes I think Becks Dark might be an appropriate element to include in the mix.

[flyguy]

Perhaps at a convention we should all bring our devices and agree to test them using more scientific methods.

I have to ask; Would this test involve Becks Dark?

SUMTYME JU JUS GOTS TU USE REELY SOFISTIKATE TESTER STUF - - HYEAR IMA GONNA TEST PULIN CAPS OFA SUM LITE AN DARK BEVER AGES . IFN I DOANT GITS ALLA WAY TRUE EVER WON AN I NEEDS HELP I KIN CAWL ON MR GAY HORN AN HESA GOTS A REAL REDNEK SLIKER WAY TU POP EM TOPS

[GAHorn]

I never thought my method of poppin' the tops off beer would "stump" you, Ol'Gar!

[HA]

not sure what redneck method to pop beer caps off y'all use down there, but up in my neck of the prairie the preferred method makes use of the big belt buckle you won at a rodeo

[wingnut]

I can imagine George's method either involves using a closed pocket knife and the heal of his hand to leverage the cap off, or maybe any convenient piece of furniture, table top etc to catch the edge of the cap, then strike the bottle top with the other. Now that I think about, beins George has Arkie kin, he may use his teeth