none ferrous type cable/wire rope

Just wondering if any one knows of none ferrous type cable/wire rope that has decent (1500-2000 lb) breaking strength? I want to replace my shoulder harness cables that run to the back of the fues with a none ferrous type material and one way is to do it with slings/webbing but was hoping to find a place that I can buy aluminum or other type material to replace the existing 5/32" thick cables.

Thanks in advance
Mehrdad
RV7A

There are companies out there that make cables out of Kevlar and the like:

http://www.applied-fiber.com/our-product.html

Not sure why you would want to change though...

Why do you want to change it? I think you need more that 1500-2000 lbs of breaking force. Impact crash forces being what they are, require much more than that. Your body can take a lot for a very short instant. Do some research on what is necessary. I'll bet 5-10,000 lbs is more closer to the need.

I was looking at Spruce catalog and it listed the breaking point for the ends that gets attached to the 5/32" cable only at 2800 lb. Most climbing slings strength is about 4000 lb and I have taken many lead falls on those and have never broken. But if I can find a stronger one, then I surely would want to use it.
As for why I want to change, my magnetometer is installed behind the baggage compartment above the bell crank just below the top of the fuse. It is more then 18" away from the cables but the cables are pretty big and I am wondering if it is affecting the magnetometer (heading on my EIFS)

Mehrdad
RV7A

Got it. I think the concern with rope would be deterioration over time. Also, chaffing. You could probably put heat shrink tubing over it and limit both.

It's hard to beat the stiffness and resilience of steel cable. You don't want to end up on the end of a relative speaking, bungee cord.
Jim Sharkey

You could try Marine SS cables. They are 300 series SS and thus non magnetic. Breaking strength would be similar to steel and there are lots of end connections available.

Bob Parry

Bavafa said:

I was looking at Spruce catalog and it listed the breaking point for the ends that gets attached to the 5/32" cable only at 2800 lb. Most climbing slings strength is about 4000 lb and I have taken many lead falls on those and have never broken...

Click to expand...

Mehrdad, I have pull-tested a bunch of climbing gear and also aircraft materials and hardware to tensile failure (search YouTube on "breakotron"). My take on this issue is that there are a couple of differences that makes comparing climbing slings to steel cables an apples-to-oranges kind of thing.

For one, climbing gear is generally rated to its breaking strength using three sigma (Aliens excepted, of course). That means that the actual breaking strength is usually very close to the rated strength, with little and sometimes negative margin. Aircraft hardware, on the other hand, is usually rated much more conservatively, with much wider margins to allow for manufacturing tolerances and wear and tear in service.

For another, the strength of a sling or runner is rated for the system consisting of a loop of material (two strands) plus the sewn or knotted joining that forms the loop. But the 5/32" cable is rated for a single piece.

If a single strand of 5/32" cable doesn't meet your needs, you can always go to 3/16" or 7/32". Have McFarlane swage on some nice terminals with their Kearney press and you'd be good to go.

One reason that I would not use nylon, aramid, Dyneema (tm), or Spectra (tm) for a seat belt anchor cable is that, as others have already observed, all those materials have much lower Youngs modulus than steel or aluminum. Of course, the seat belts themselves are nylon, that's unavoidable. But the more of those elastic materials you have in your restraint system, the more the system will stretch under load and the less margin you have between your body and the things you want to restrain it from.

Thanks, Bob K.

Why not

just use stainless aircraft cable?

non-ferrous type cable

Any practical news on this?
Has anybody found and used SS cables?
Or is there a way to neutralize the ferrous aspect of the original steel cables?
I'm also worried about interference with the magnetometers

Originally the RV shoulder harness used seat belt material further back into the tail-cone. The reason for the change was elasticity. The seat belt material had too much "stretch" and made the shoulder harness essentially ineffective.
Mine are stainless and don't seem to affect my compass module at all.

mehrdad try these guys, they should have some stainless cable you could use.

http://www.acmerigging.com/

it is used a lot for railing restraint, called decorative but there shouldn't be a problem finding proper strength sizes

I went through this process for a different reason. I used inertial reel shoulder harnesses and the inertial reel needs to be mounted securely so that there is no slack in the entire system. The standard Vans cables were too long and would have flopped about midway between the baggage bulkhead and the seat back, providing so much slop that the inertial reels wouldn't have locked until after my face was through the panel

I called Vans and they suggested that I go to a marine rigging place and get some stainless cable and have them cut it and swage it to whatever length I needed. That's what I did. My magnetometer is also back there and there are no issues.

All Best

Jeremy Constant

Dyneema rope will do well. It's a low-stretch marine rope used on sailboats and other applications. Although it's low-stretch, it still stretches more than wire rope. The numbers for Young's modulus are about 4 or 4.5 million psi for the Dyneema and about 11 or 12 million psi for the steel cable, so if you double the nominal diameter for the Dyneema, you'll be okay for low-stretch.

And Dyneema's strength is so great that it simply won't be an issue. It's very light. I think it'll float.

The caveats and gotchas are:

1. The Dyneema is slippery and knots aren't reliable. Worse, they'll break at relatively low loads. Only a proper splice should be used, such as this one, which is fun to make:
http://www.neropes.com/SPL_12Strand_EyeSpliceBrummel.aspx

Personally, I can't splice this if it's thinner than 1/8" thick, and that's difficult. Thicker is easier.

Incidentally, the buried end needs to be well-tapered and buried at least 44 times the diameter. The easy way to taper it is to bring it out of the cover (bunch up the cover) below where you want the end to be, cut the taper on the individual strands, and then pull the cover back over them.

2. The Dyneema is sensitive to stress concentrations and won't develop its strength around sharp edges or small radius objects. Ideally you need something like 8 times the rope diameter for the diameter of the object the Dyneema is wrapping around. Smaller gives proportionally lower strength, and since the rope strength in the oversize diameter is high, you might be able to get away with it in some applications.

3. Dyneema creeps. If there's a steady load it'll gradually stretch. You wouldn't use it for control cables, for example, since they generally need tension.

4. It's pretty abrasion-resistant and fairly UV resistant. In both cases it'll wear or soften on the exposed fibers and you can see and feel that. But it's not as durable as wire rope in that regard.

5. Being a low-stretch rope, it doesn't absorb much energy when loaded. You would not want to use it for climbing, for example, if you fell, the shock would be very severe.

You can get Dyneem from places like http://www.apsltd.com/c-1492-amsteel-blue-samson.aspx, under the trade name "Amsteel Blue."

It's good stuff, when used with knowledge of its characteristics.

Dave

I have been trying to calibrate my dynon skyview compass without success. My best guess now is that my steel seat belt cable is the culprit. the adahrs/magnetometer lies about 8" above the steel cable.

Update: well, i removed the cable and am still getting the darn error. i seemed to have ruled the cable out.

I asked a similar question about a week ago but due to the trim cable location on an RV9A relative to the Garmin GMU-44. I have been told that you can demagnatize the cables (degausse) sp? either with a permanent magnet or with an electro magnet. I am still researching......

Regards,
Jamie

non-ferrous type cable

Thanks for that info, Jchang, I have also two Skyview Adarhs in the proximity of the cables, at about the same distance. I'll try to calibrate with the Van's cables.

I was at West Marine today getting some supplies and found that they will sell you SS wire rope and swag the fittings on in the store! Here is the link to there catalog page.
http://www.westmarine.com/webapp/wc...toreNum=50045&subdeptNum=50088&classNum=50090