Ratchet Straps vs Rope

[David Paule]

While it's always nice to have well-educated tiedown equipment, it's far better to have taut ones. Tight is good.

Dave

[ronschreck]

Originally Posted by 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

I'm going with Dave on this issue. (Hard to argue with an aerospace structures engineer!) Tighter is better. Those of us who survived the Sun'n Fun tornado of a few years back learned a few things about tie down anchors as well. The corkscrew dog tie downs are great for dogs, not airplanes. Plastic tent pegs are for tents, not airplanes. Even "The Claw" tie downs failed when improperly secured. And slack ropes tore out the best of tie downs and sometimes pulled the anchor point from the wing of the airplane.

My own plane was tied down TIGHTLY with good anchors and stayed put. Two planes that were parked 50 feet away from me were yanked from their improperly secured anchors and were totally destroyed. The only damage I incurred was from blowing debris from other airplanes.

[woodmanrog]

on what you encounter. Here is a pic of a newly restored Beech 18 after a tornado came through during hurricane Wilma. It was anchored in CONCRETE and actually pulled the concrete plugs out of the ground. Notice the smaller aircraft tied down with ropes in the background. The hole in the foreground is where the tiedown was.

[rgmwa]

Originally Posted by ronschreck

My own plane was tied down TIGHTLY with good anchors and stayed put. Two planes that were parked 50 feet away from me were yanked from their improperly secured anchors and were totally destroyed. The only damage I incurred was from blowing debris from other airplanes.

What kind of anchors did you use?

[MarkW]

My oppologies to the Op as I am going a little of topic but.
I have not been happy with the tie-down kits I have seen available for aircraft. The SNF tornado year is a good example of what does not work in the Florida sand. I found what I think is the perfect set at Harbour Frieght for less than $20.
[IMG][/IMG]

You up North guys may laugh at trying to get these screwed down in your soil but they are perfect for our sand. I bought better dock lines and put it all in a $5 tool bag from Sears along with the canopy cover and tie-down rings and I am ready for SNF this year.
[IMG][/IMG]

[Toobuilder]

Tight is good, IMHO.

I've experienced damage to an aircraft that's allowed to build up a good head of steam before slamming the end of a chain.

You would have to ask: Which is worse - the dog straining at the end of its rope trying to bite the mail man, or getting a good running start first?

Besides, has anyone considered how the US Navy ties their aircraft down? Seems like they'd be the experts.

[RVbySDI]

Originally Posted by MarkW

My oppologies to the Op as I am going a little of topic but.
I have not been happy with the tie-down kits I have seen available for aircraft. The SNF tornado year is a good example of what does not work in the Florida sand. I found what I think is the perfect set at Harbour Frieght for less than $20.
[IMG][/IMG]

You up North guys may laugh at trying to get these screwed down in your soil but they are perfect for our sand. I bought better dock lines and put it all in a $5 tool bag from Sears along with the canopy cover and tie-down rings and I am ready for SNF this year.
[IMG][/IMG]

Mark,
my apologies for disagreeing with you but those tie downs look just about identical to what I used at the 2011 SnF tornado. They were totally useless in the loose sand that was masquerading as soil on the SnF grounds. You can see the tie-down dangling at the end of the rope tied to my tail in this pic:


I have tried many different varieties including the 'CLAW' and feel none have the potential holding power needed. Perhaps trying to protect against a tornado is an exercise in futility. However, since I have first hand experience now, I have been interested in at least attempting to find something that works. To that end I have been using these tie-downs since March 31, 2011:
Stormforce tie-downs


P.S. I have no affiliation to the Storm Force company, just a satisfied customer.

[alpinelakespilot2000]

For anything short of hurricanes or tornadoes (i.e. normal use), what would be an appropriate load limit rating for either ropes or straps?

[MarkW]

Hey Steve,
I am sorry as it looks like you recieved some damage that year.
Any idea how deep you had the twist ins? It is true that if you don't get down into the solid wet stuff it would not be secure. But I can't imagine the spikes (large nails) that are supplied by most of the kits doing any better. I have used most of the kit ones available and the 15" twist ins are far superior. As you said protecting against a tornado is futile. However we do get plenty of afternon thunderstorms that will blow hard for a few minutes and I sure plan to try.

[RVbySDI]

Originally Posted by MarkW

Hey Steve,
I am sorry as it looks like you recieved some damage that year.
Any idea how deep you had the twist ins?

They were buried to the hilt. the only thing above ground was the eyelet the rope was tied to. At SnF you could most likely dig to China and not find a hard enough surface to secure the tie-down. That sand was as compact as quick sand. In fact the rain was fierce Monday prior to the tornado. There was probably 8-10 inches or more of rain that fell between Monday-Thursday that year. The ground was absolutely saturated with water. The sand had the holding power of powdered sugar.

Originally Posted by MarkW

It is true that if you don't get down into the solid wet stuff it would not be secure. But I can't imagine the spikes (large nails) that are supplied by most of the kits doing any better. I have used most of the kit ones available and the 15" twist ins are far superior. As you said protecting against a tornado is futile. However we do get plenty of afternon thunderstorms that will blow hard for a few minutes and I sure plan to try.

I don't know if the spikes would do any better in that loose sand. Not sure if anything could. However, I disagree with you concerning the "twist ins are far superior." That twist in corkscrew is just stirring up that sand (loosening the already loose sand) exactly where you expect the holding power to be. That corkscrew plate is plowing through the sand and turning it up above it. The spikes on the Storm force are driven into the ground at a 45 deg angle into the ground and placed such that the rope angles out and away from the tie down ring on the plane. This puts the 4 spikes at a 90 deg angle to the pulling force of the rope. This allows for the entire length of the spike to be used against the pulling force. There are 4 of them per tie-down. FOUR separate spikes in the ground to pull against instead of ONE. I think when one examines the geometry of the 90 deg angles to the forces administered, one will find there is more holding force on 4 spikes angled into the ground perpendicular to the pulling force than would be in one twist in corkscrew tie-down.