Ratchet Straps vs Rope

[flightlogic]

Your carabiners have softer edges than my ratchets. Must admit.
And knots are a thing of beauty...

[Aerosporty]

Tight tie downs put a negative G load on the aircraft...constantly . Not the best plan.

[MikeT]

I have a J-3 Cub on floats I keep in my backyard all summer long. I prefer motorcycle tie downs for the ease of use, but if your going to use them, do not use the kind with the open hook. Use the kind with the spring loaded catch that you have to move out of the way to unhook. Several years ago at Sentimental Journey, a Cub get together, a storm came through and several planes using the open hook tie downs became unhooked and damaged not only their planes but others too. If all you can find is the open hook type, use ropes or chains, all the other people with planes around you will be happier.

[N64GH]

I use rope and a modified truckers hitch (uses part of the rope as a pseudo pulley) lets you get it tight, works great.

[tspear]

The sailing reference brings to mind something I have not thought of before. Has anyone used boat spring lines? No jerking, gradually increasing pressure.

Tim

[JCSmith]

While this may stir up the whole debate about touching someone else's aircraft, I'd like to share a quick story. While driving down the ramp on an exceptionally windy day, I noticed a Cessna 172 with only one wing tied down with a strap with a spring pressure button instead of the ratchet assembly. On the other wing was the upper half of a strap including the buckle assembly swinging wildly in the wind, beating the heck out of plane. I attempted to re-buckle the second strap, but the spring had failed and it wouldn't hold the strap tight. There wasn't enough strap to tie the two half's together and no one was around to notify. I ended up getting a spare tie-down rope and secured the plane. There were dents and scratches all over the plane from the swinging buckle.
I'll stick with rope, thank you!
And yes, when the plane disappeared a few days later, my rope apparently went with it.

[scard]

Originally Posted by tspear

The sailing reference brings to mind something I have not thought of before. Has anyone used boat spring lines? No jerking, gradually increasing pressure.

Tim

I'm guessing that what you're referring to is what I used to call a rubber ducky, with all the connotations . Dock line wrapped around a large elastic element. Very heavy when sized appropriately, short term life, and needs pretty large (slow) inertia to work correctly. I would not call it a 'spring line' at all in proper terms at the dock.
But, if we wanted to do a very funny, big pain in the rear, certain shock absorbing tie down, we could certainly tie down an airplane just like Tanya and I did an eight ton vessel for years at the dock . Now that is a girl that knows how to work a spring line and not go in the drink!

[videobobk]

Back in high school, I worked on a river boat in the summers. There, it was cables, or ropes. While a cable was much stronger in absolute strength, it would not absorb shock and stretch. Let a 200 tons barge drift 10 feet and hit the end of a cable, and it snaps. Not so the rope. I believe chains, no matter how well tightened, can work into a slight amount of slack. They may not break, but they will put very high loads when they hit their limit, perhaps enough to do damage.

I had a Phantom ultralight tied down with ropes when a tornado lifted the hangar away. The 1/2" ropes were down to about 3/8" and stiff from stretching. No damage to the u/l. All the other planes in the row were destroyed or seriously damaged, and some were not tied down being inside. Ropes can't be beat. That said, I have switched to straps. They do have a slight amount of give, and can be tightened nicely. They are hard to beat for convenience. I rarely tie down outside (ALWAYS tie down in a hangar) but still prefer ropes there when I do.

Bob

[walkman]

Originally Posted by Ironflight

Chains in the west, ropes in the east - seems to be the norm for environmental conditions.

I'm in the tight rope camp - why do you think we have the Taught Line Hitch? If I want 'em really tight, I'll take a bite in the middle and tie it with an extra reduction - nothing moves. This way, I am only carrying rope and a few 'biners - ratchets just take up a lot of space.

bight

although the image of you with a rope between your teeth.....

[David Paule]

What's needed is stiffness and tightness. You don't want any slack, and springy ropes or straps are not desrable. Use ropes of polyester, not nylon or polypropylene. Climbing ropes are generally too stretchy. Marine ropes with a polyester cover and a Vectran or arimid core are ideal; a Dyneema core is good too.

Tie knots that can't come loose no matter what happens. Some knots can loosen if the rope goes slack and tightens, so don't use those. That means no open hooks, too.

Make certain there's no slack. Ropes that are very tight are best. The plane can handle that. It's the dynamic bouncing around that breaks the ropes and wrecks the planes.

I've seen too many aircraft broken after a storm event because their owners didn't follow these suggestions. Since I'm an aerospace structures engineer, it was pretty interesting to figure out what happened.

On my plane, I tie one wing as tight as I can. At the other wing, I try to tighten it as much as possible too. I'll actually hang on it to grt some tension. Then I loop a rope around the tailwheel assembly and pull the plane aft until it's as tight as possible. All knots are right at the aircraft or ground anchor.

Good tiedown equipment and techniques only really matters in severe conditions. So alwayes be prepared for those. Make it a habit.

Dave