Been looking for some good tiedowns I can take with me. Gonna be spending some time off field at different locations and need something that works when there isn't anything else available. Most of the reviews for some of them don't look too good.

Hard to beat duckbill anchors for holding power in nasty weather. You can't take 'em home with you after pounding them in, but they're relatively inexpensive. Tie some flagging tape on them and they'll be there for the next guy to use. There's at least one set at many backcountry strips in Alaska.

Really depends on what sort of soil you're on. There's a few threads that address field tie downs...and few opinions that coincide.

As already mentioned, duck bills are probably the most secure option overall, providing you choose models that are large enough for the soil YOU'RE on, not based on the advertised holding power. They don't do crap in river cobbles or gravel that's mostly void of sand, and even at $8 a piece, that's $24 per set...and you also have to cary a sledge hammer and a driving rod. Also, they need to be tended, as they will pull up an inch or three under load before they set, at which point a airplane will rock and shock-load them if the lines aren't retightened.

As for people using them after you're gone...maybe. Anywhere there's any real wind, most people won't reuse duckbill's of unknown size or age. I know I wouldn't.

In good soil I use a series of two or three wooden pickets tied together...a mainstay of traveling circuses, in countries that still have them.



In frozen soil I'll use the Claw, though I don't trust it any other time. None of the commercially made tie down anchors strike me as reliable in many soil types, though they're better than nothing, unless they prompt you to stay when you'd have left without them. At that point they're quite a bit worse than nothing.

Note the commercially available tie down anchor hanging off the tailwheel...


Digging holes and pushing the mains in works pretty well to increase the holding power of marginal anchors for a tail dragger. It lowers the angle of attack, and acts as super-chocks. The bigger the tires, the better it works. But be warned, if you burry your mains up to the axel, neither your back or your propeller will get it out, no matter how much digging you do to build a ramp. You have to have a mechanical advantage and appropriate anchor to pull the airplane out; best to figure that out before pushing the mains into the holes.

Sometimes you have to get really creative. I've had as many as eight lines going to different parts of my airplane when thunderstorms were rolling around and there was no option for three good anchors. Whether it worked or I just got lucky I don't know, but my airplane never flipped over.



If you want any level of security then you have to learn about anchors, soil, rigging, and vector forces, then decide on the spot what the best solution is. No one solution is going to fit all scenarios.

Ok I’ll ask, what the heck are “duckbills” other then the obvious ones found on the winged & feathered species

duck bills are driven into the ground with a rod, they have a cable attached to them that when you pull on it, it wedges itself in the ground. like a piece of pipe with an angle on one end. drives in straight, load it and the "bill" turns against the direction of pull.

Look here: https://www.amleo.com/duckbill-earth-an ... gIWxPD_BwE

MTV

Mapleflt wrote:Ok I’ll ask, what the heck are “duckbills” other then the obvious ones found on the winged & feathered species

Google duckbill anchors and then click on images. There are lots of pictures there that make the concept clear.

I carry the driving rod and three anchors with me at all times, but don't worry about a sledgehammer. I can usually find a rock or part of a tree to do the job, though sometimes I hurt a few fingers in the process. When I leave 'em behind, a stop at the hardware store on the way home solves that problem.

Thanks for the replies, good stuff.
This is a cabin down on the Alaskan Peninsula that we stay in. Years ago, it has been moved by strong winds more then 10 yards. So now it's tied down. At this location, we did use old tires dug down 4 feet and buried in the ground. Winds can get close to 100 in winter. We've seen 50 mph here while we were tied down.

These are hard to beat, rated at 1000lb. Just add sand, gravel etc...

https://m.lowes.com/pd/AWP-1-Count-89-G ... g/50176191

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Those Duckbill anchors look really cool. Which model do you guys suggest for something like a 175? How much does the kit weigh?

Model--Working load
40 300lbs
68 1100lbs
88 3000lbs
138 5000lbs

Well lots of commercial products out there. My experience in building the runways and securing a few hundred aircraft at Burning Man; turns out that simple is almost always better. It is really just down to physics. We found that fewer aircraft pulled out their tie downs if they used the following: 3 pieces of re-bar about 24-30" in length, preferably with one side cut at an angle. The angle allows it to be more easily to be pounded in to the ground or a vampire's chest. The three pieces at each tie down are pounded into the ground at about a 30-40° angle and directed at 120° intervals. Secure a loop around the nexus where the three pieces of re-bar meet and tie your tie down to that loop, make it tight. So for the average airplane, you need 9 pieces of rebar. This worked really well on the Playa for everything from Cubs to Caravans. Putting three in an equilateral triangle kind of setting allowed forces to move around and still have a tie down to resist in that direction. Besides it is absurdly cheap and can be free.

Now where this does not work, it is on cobbled or really rocky ground. Then; dig a hole and bury two pieces of re-bar like a cross, with a loop that will project above the ground level, and backfill with your rocks, cobbles and dirt. For loops, I like climbing webbing, cheap and absurdly strong.

Another nice thing we recommended; three tennis balls with holes on one side to put over the exposed rebar. We also recommended some survey streamer (which we would provide if asked) to put on the tie down ropes themselves. People still "cloths lined" themselves all the time on the flight line. Something else had to be interfering with their attention. When you transport the rebar, secure it in a bundle and put the tennis balls over the ends to neuter them.

falconefive wrote:Those Duckbill anchors look really cool. Which model do you guys suggest for something like a 175? How much does the kit weigh?

Model--Working load
40 300lbs
68 1100lbs
88 3000lbs
138 5000lbs

Again, it really depends on the soil you're parked on. And your budget...

I consider the 68 to be adequate in good soil for normal wind conditions...less than 40 knots. The anchors don't weigh much, but the sledge and driving rod are probably five pounds or more. Trying to improvise the driving tools doesn't work...forget using a rock instead of carrying a sledge.

Do NOT use them anywhere that the grass is cut, or bring cable cutters and cut the cables off a couple inches under the surface when you leave.

Don't forget that you cannot retrieve them without a shovel and a lot of digging, and three 68's will run you about $24, and 88's will be more than twice that. 138's are impractical to drive without a jackhammer.

And more than you ever wanted to know: Duckbill installation.

https://amzn.to/2LqPE9W

About $78 for a pack of 6 with the drive rod.

Similar to what Hammer said, if the ground was soft enough, I'd dig a little divot out, then drive them until the loop is slightly subsurface but visible (that's pretty damned deep.) If you can't get it that deep you might need to use a cable clamp to make a loop and then clip the tag end off. Then tie off with your own tie-downs using a carabiner. They're there for the future, but without a long piece of cable sticking out of the earth to catch...whatever. Probably not such a concern at real backcountry spots as it is a state airstrip where they might mow it once a year.

There are lots of other retrievable tie-down kits on the market.

TradeCraft wrote:These are hard to beat, rated at 1000lb. Just add sand, gravel etc...

https://m.lowes.com/pd/AWP-1-Count-89-G ... g/50176191

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In marginal soil like river cobbles or gravel, there's a distinct advantage to dead-man anchors instead of in-the-ground anchors. In-the-ground anchors, once they start to pull, generally give up all their holding power...one big gust loosens them, and then they're completely compromised. And in poor soils they generally have marginal holding power to begin with. NONE of the commercial tie-down anchors I've ever seen is worth a tinker's dam in gravel or sand or silt.

A dead man anchor (like a sack full of rocks or sand), can lift up in a gust, but when it settles back down it's as secure as when new. Of course it has to be heavy enough to actually work, but in marginal soils, that might be the only realistic option.

You really have to tailor your solution to your environment. On a gravel bar which is comprised mostly of large cobbles or sand-free gravel or uncompacted sand, I'd take a 800 pound sack full of rocks and sand over anything I could drive into the ground. Others disagree (strongly), so it's really up to each individual to figure it out for themselves. Good insurance is a nice back-up.

Hammer wrote:Trying to improvise the driving tools doesn't work...forget using a rock instead of carrying a sledge.

I disagree. I’ve driven multiple sets of duckbills into the Alaskan backcountry with rocks and tree limbs. It’s a pain in the ass - obviously harder to do than with a proper sledgehammer, but it can be done.

Brian M wrote:

Hammer wrote:Trying to improvise the driving tools doesn't work...forget using a rock instead of carrying a sledge.

I disagree. I’ve driven multiple sets of duckbills into the Alaskan backcountry with rocks and tree limbs. It’s a pain in the ass - obviously harder to do than with a proper sledgehammer, but it can be done.

Depends on the soil. Sometimes it cannot. I've proved it!

Brian M wrote:

Hammer wrote:Trying to improvise the driving tools doesn't work...forget using a rock instead of carrying a sledge.

I disagree. I’ve driven multiple sets of duckbills into the Alaskan backcountry with rocks and tree limbs. It’s a pain in the ass - obviously harder to do than with a proper sledgehammer, but it can be done.

If we aren’t tired of anecdotal evidence yet, I have managed to bend 2 or 3 drive rods with a sledge trying to get a duckbill into the Alaskan backcountry. No way would I plan on getting one in with a rock if I haven’t been there before.


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I used duckbill earth anchors for twenty years that my airplane was parked outside. That was both while the plane was on floats and on wheels. Driving them in underwater is fun.....but they work, day in and day out.....even as semi permanent tiedowns.

A couple of points:

The drive rods that are available for sale with duckbills are not great. They are relatively light duty, so can bend (see Prosarias comment above) relatively easy. They are also not long enough to really sink a duckbill. I got the duckbills, then got a piece of rebar of appropriate diameter, and long enough to drive the entire duckbill and it’s cable underground. Now, you can drive them in deeper, eliminating the concern about leaving a loop of cable above ground.

Concerned about weight? Light is great, and duckbills are pretty light. Drive hardware is a bit heavier, but having your airplane airworthy after a blow is worth a lot.

Same applies to cost.

As noted, they won’t work as well in every soil type. Neither will anything else. That said, duckbills, in my opinion, work better in most circumstances than any other single solution.

Mind you, I use one of the common commercial solutions for “normal” circumstances. The duckbills are there if the shit really hits the fan.

MTV