Nicopress Question

[N74DV]

My dad is building an all wood Fisher Celebrity biplane. He's at the point of making the flying/landing wires. The plans say to use two Nicopress sleeves per end. I say only one is required. I see two all the time at fly-ins on homebuilts and I have always thought it was something builders did as a sense of redundancy but really? As I understand it a properly compressed sleeve will slip/fail well after the cable has failed making two sleeves on the ends kind of silly. Also I have understood that two sleeves may stiffen the wire between the sleeves and be more prone to fatigue in that area.

So... what's the consensus? One sleeve is sufficient? Does two really add any level of redundancy if the sleeves are properly compressed?

[N96337]

Re: Nicopress Question

One proper sleeve is enough, just like you thought.

[Guest]

Re: Nicopress Question

copper sleeves or aluminum?

will the FAA inspect to see if you meet the drawings and specifications?

[astjp2]

Re: Nicopress Question

Its amateur built experimental, he could use 16d nails and be signed off.

copper sleeves or aluminum?

will the FAA inspect to see if you meet the drawings and specifications?

[Robert Lees]

Re: Nicopress Question

If the plans say two, do two. Follow the plans, it makes it easier in the future.

Ours is not to reason why....

[woodmw]

Re: Nicopress Question

The plans probably call for two because the designers don't know the skills or equipment that will be used to squeeze the sleeves.

It may be E-AB, but some in our local EAA have found that the DAR guys are not just signing off what ever the builder wants to do. They do consider best practices guidelines. Still, there is a lot of latitude. But I doubt that in this case, one could get by with a couple of half hitches and duct taping the tag back to the line.

[crispy critter]

Re: Nicopress Question

Use two as per the plans. I used to have the same opinion as you about the flying/landing wires until an older and much wiser builder/restorer explained it so it makes perfect sense. Our flight control cables on most aircraft using nicos only have 15-20lbs of tension in most applications. Rarely do they ever have more the 50-100lbs of tension under the most extreme control imputs.

With that said, the flying/landing wires properly rigged will carry 50-100lbs setting parked in the hanger(depending on the type of biplane, the fisher will tension around 40-60lbs). While in flight the flying wires carry the entire weight of the airplane plus all the extra G loads that apply. The landing wires take all the weight while parked, any inverted loads and negative loads, plus all of the shock loads from hard landings rough fields,etc. You need do double them, in fact i usually use a size bigger wire then the plans call for plus I double the nicos like the plans call for.

[astjp2]

Re: Nicopress Question

If I remeber right, a proper nicopress is around 1,500 of tensile strength for 1/8"

[crispy critter]

Re: Nicopress Question

Yeah, I think that's about right. I have also seen them cracked on a very rare occasion. The flying/landing wires are your life line, if one fails more then most likely your only going to have a few seconds to wish you had followed the plans and used two. Why would you not want the extra security and safety?

[astjp2]

Re: Nicopress Question

Too much Weight!

[shipljl]

Re: Nicopress Question

The instructions on my swage tool says "When using 1x19 strand cable, use two sleeves at each end to obtain proper holding strength".

[astjp2]

Re: Nicopress Question

We use 7x19 cable in aircraft, and real aircraft cable has a thread woven into it that is colored so they can identify the manufacturer. 1x19 is good for fences though. Tim

[baldeagle27]

Re: Nicopress Question

1x19 is fine for any cable that doesn't have to change direction (go around a pulley or fairlead), like flying and landing wires, and is slightly stronger than 7x19.



-

[Garry Crookham]

Re: Nicopress Question

The Fly Baby uses 1x19 cable with only one sleeve. Pete Bowers (Fly Baby designer) stated that the cable is rated at 2000lbs with proper Nicopress sleeve installation and the turnbuckles in the system are rated at 1600lbs.

Garry

[Bipe215]

Re: Nicopress Question

The Fly Baby has all wires in pairs also. Pete flew on single wires for demonstration purposes.