Another Tail Wire Thread

[BTAZ]

1x19 5/32" stainless has a higher "breaking point" (28 to 3300 lbs, https://www.chain-cable.com/wirerope.htm ) so would seem to eliminate off the shelf 3/16" tail wires as a possible option.

[marcusofcotton]

Since I was bored.....

Bruntons gives a "Min. strength Spec." for 3/16 wires as 2100lbs for round, 2400 lbs for streamlined. (http://www.steenaero.com/products/flying_wires.cfm)

The common "Breaking Strength" spec for 7x19 5/32 stainless cable is 2400 lbs.(http://www.fairburyfastener.com/cable_specs.htm)

So if one could "tease out" an appropriate length set of 3/16" wires from production aircraft using data available at Univair, it would probably be worth talking it over with Bob.

UPDATE; per Mark G. the cable needs to be 1 x 19. 1x19 5/32" stainless has a higher "breaking point" (2800 to 3300 lbs, https://www.chain-cable.com/wirerope.htm ) so would seem to eliminate off the shelf 3/16" tail wires as a possible option.

FWIW, Normalized 4130 yield strength of 63,100 psi at .200" diameter results in 1980 lbs yield strength.

[schu]

Here is what I did: I had studs swaged on both ends of 1x19 cable and simply adjust by putting in one turn at a time. The cable will never be able to come out.

My threads are cut not rolled, so there is that, but everything has 3/4" or more of thread engagement so I'm not concerned.

The Brunton wires are the best option, but I think what I did is perfectly safe, and if you have a lathe and order the pre-made cables from ACS, it could be done pretty cheap.

[Bcone1381]

Say I don't want to pay ~$800 for streamline tail "wires".

Its still painful, but my tail wires from Steen Are Lab (purchased with a group buy) invoice dated June 2017 was $547 + $72 shipping = $619.

Going back to the Univair option I keep asking some reasonable questions...
1) Does BTAZ have his Univair Invoice to cross reference the parts?
2) Could Univair tell us which wires from there stock will fit our aircraft?
3) If none are an exact fit, would Univair manufacture them for us if a group buy was organized by us for a small production run?

[Mark Goldberg]

Matt - for flying you need jam nuts on the end fittings. They tighten the threads to each other and keep vibration or chattering in the threads down. Mark

[BTAZ]

Mark has put time and effort into developing a source for tail wires. He should be rewarded for that so I am not going to "spoon feed" alternative solutions

I did the homework starting here( http://www.univair.com/technical-resources/) to find out what "standard" tail wire lengths are available and found a set that worked for my LSA

Details are in my build log and typical "off the shelf" round wires without terminals are around $35/pc.( http://www.univair.com/search.php?se...31-002&Search= ) while typical streamlined wires are around $85/pc ( http://www.univair.com/aeronca/contr...ailbrace-wire/ ) at Univair

[schu]

Matt - for flying you need jam nuts on the end fittings. They tighten the threads to each other and keep vibration or chattering in the threads down. Mark

There are jam nuts, that's a mockup picture. But thanks for the heads up.

[BTAZ]

Its still painful, but my tail wires from Steen Are Lab (purchased with a group buy) invoice dated June 2017 was $547 + $72 shipping = $619.

Going back to the Univair option I keep asking some reasonable questions...
1) Does BTAZ have his Univair Invoice to cross reference the parts?
2) Could Univair tell us which wires from there stock will fit our aircraft?
3) If none are an exact fit, would Univair manufacture them for us if a group buy was organized by us for a small production run?

1. Details of what I used for my LSA are in my build log but typical "off the shelf" 3/16" round wires without terminals are around $35/pc.( http://www.univair.com/search.php?se...31-002&Search= ) while typical streamlined wires without terminals are around $85/pc ( http://www.univair.com/aeronca/contr...ailbrace-wire/ ) at Univair

2. Of course not. It is our job as a builder to work out the correct part number. If someone doesn't want to do that, buy them from Mark.

3. I doubt it. "Standard wires" will have a price and availability advantage because of volume. I'm sure Univair(and all the other sources) are re-sellers only.

[Bcone1381]

Mark does not supply tail wires. Mark promotes the group buy thru Steen Aero Lab in order to help us, the builders of his kit save cost. He does not get involved beyond that. In other words, the wires are ordered by the builder from Steen, Shipped directly to the builder by Steen, and payment was made by the builder to Steen. I already have my wires. I think your method is superior. Post #19 was request to help the community and I believe takes no business away from Mark.

I won't apologize for what I wrote above. Helping others and removing barriers to building is a good thing. If Rebranding it as spoon feeding becomes widespread this forum has no purpose to exist.

[BTAZ]

Given I didn't purchase the "group buy" tail wires, obviously I have misunderstood how the purchase is handled. My assumption was it was similar to the windshield where a custom part number has been created by the manufacturer(in the windshield case, LP Aero) and is only available through Mark and that Mark is rewarded(as he should be) for his efforts.

Perhaps I misinterpreted your questions as "accusatory" ("Here are the specifics of my wire purchase, now put up or shut up.") and leading ("Why would Univair have any idea what the correct wires are for a Bearhawk?").

As far as "spoon feeding", myself and others have provided some relative strength numbers(most with references) for the "options" (Custom wires, 1x19 5/32" cable, 3/16 stock wires, 4130 rod reduced to .200" between threads), I have posted in more than one thread(including this one) what worked for my LSA and I have provided a link where common production lengths can be found and priced.

A Patrol or four place builder now needs to "Pick up the torch" and see if there are production wires that would fit and get Bob's blessing for their use(note the LSA plans specify 10-32 for the wire fittings so there isn't a question whether typical 3/16" wires are an acceptable diameter).

[Archer39J]

Looking at the Univair website I can't find any supporting documentation for those wires that specify their length. So it'll take some more digging to find that out. If I were building an LSA it sure would be nice to know what part numbers others have used. If I find a suitable part for the 4-place I'll post it here.

ETA: Steen prices are $847 for the whole package, $547 for just the wires. So $41/piece for terminal assemblies? That's the group buy discount, individually it's $200 more.

[Bcone1381]

I recall thinking Steen's price on the terminal hardware was high, though made of stainless. I think I got cad plated thru Spruce.

[BTAZ]

Here(and there may be others):

http://www.univair.com/content/ChampTBWires.pdf

http://www.univair.com/content/Piper-TB-Wires.pdf

http://www.univair.com/content/TCRAFT-TB-wires.pdf

http://www.univair.com/content/Cessna-Drag-Wires.pdf

[Archer39J]

Awesome, thanks!

[Archer39J]

Assuming "S.S." means something like 18-8 (annealed) it seems doubtful Univair wires are suitable replacements for wires specified by Bob's design. The significantly lower yield strength in addition to the reduced diameter takes it pretty far below the envelope for my taste, the yield of SS is 49% that of 4130 alone, and I doubt there's much over design given what I've seen elsewhere.

Looks like I'm back to ACS pre-made cables.

[Archer39J]

And Bruntons are 316, so what gives?

[Archer39J]

The profiled SS wires have been cold worked and are therefore stronger than the round bar. 4130 round bars and SS round bars are not equivalent and the breaking strength is only one of the factors for this design. As always it's your experiment.

[BTAZ]

And that's why I refuse to put forth more than suggestions as it is up to the builder and their research to make their own judgement.

That said, AFAIK, there are only two companies in the world making these wires, Bruntons and one in NZ( or possibly Australia, was discussed in a different thread). It is very likely that the wires being resold by Univair, Spruce, and the rest are coming from Bruntons and the price delta reflects volume.

As far as "strength isn't everything", that is absolutely true. A bit of research will turn up a couple Fly Babies that lost their wings in flight, likely because builders replaced the wing landing/flight cables defined by the print with flying wires for cosmetics. For various reasons, the wires cracked and failed catastrophically where cable is much more tolerant of vibration.

So if I was building a Four place or Patrol, I would see if there were "standard production" appropriate length wires available. If there aren't then I would choose one of the already defined/approved methods(Bruntons, cable, made from 4130 rod)

But if there were "Standard production" appropriate length wires available, I would give Bob a call and post the conclusion here.

[Bcone1381]

A call to Univair and APR 2007 issue of Beartracks revealed some facts and allows truthful comparison between Bob's tail wires and what Univair can offer the Patrol and Four Place builders.

Bob's design calls for round 4130 steel tail wires that are 42.5" and 48" long, .200" in diameter with .250 cut threaded ends.

Univair's tail wires are all round, none are streamlined, made from 302W stainless steel. The longest that the offer is 42.5." All are .168" diameter with .125" rolled threaded ends. Univair has their wires made up. They cut the wire to length, then send out the wire to have the threads rolled by a subcontractor, 1000 wires at a time.