Ruslan -have you tested the various size lines to failure? If so, what (roughly) will they take? We can handle newtons or kg, and no one will hold you to it, but what is the range of failure tension? It is tempting to use the .0145 lines, but I would probably want to maintain some margin over the pull test to address fatigue.
Brett
Hello Brett
I have tested all available lines of different diameters and different materials for rupture.
To do this, I took a piece of a line 5 feet (1.5 m) long, sealed the ends on both sides in different ways, with copper pipes, copper wire, Kevlar (like Lauri) and pulled very slowly, without jerks, attaching one end through a thick wire to a heavy iron table and the other end to the hook of the electronic scale, which showed me the growing weight in kg or lbs. During the destruction of the line, I memorized the readings on the scales.
A 7-core stainless steel line with a diameter of 0.015 collapsed at a load of 11.5 - 12.5 kg, which is 25 - 27 pounds.
The stainless 7-core line, 0.018 in diameter, collapsed at a load of 17.5-18.5 kg, which is 38.5-40.5 pounds.
The line is brass plated, 3-strand, 0.0145 in diameter, collapsed under a load of 22-23 kg, which is 48.5 - 50.5 lbs.
The brass plated 4-strand line, 0.0165 in diameter, collapsed at 23-24 kg load, which is 50.5 - 53 pounds.
The brass plated 4-core line, 0.018 in diameter, collapsed under a load of 27-29 kg, which is 60-64 pounds.
Brass eyelets always start to collapse, stretching into an oval after a load of 24-25 kg, that's 53-55 lbs. With such a load on one line, which is 50 kg or 100 pounds if it is applied to the aircraft through two lines, the metal elements of the aircraft control system are completely destroyed.
I currently only use 0.0145 brass 3 conductor lines. This is the best option for F2B. These are very strong carbon steel lines and are afraid of tight bends unlike the 7 strand stainless lines. I've tested a lot with different line end terminations. This is all on the personal desire of the athlete. There is no difference in strength. There is only a difference in ease of use and manufacturing capabilities. Whoever has what hands are capable of doing so. I wrapped it around the eyelet once or twice. For a brass-plated cable, one revolution is better. At two revolutions, there is a slight backlash, or damping, which leads to rapid destruction after 100-150 flights. For stainless steel wire, it doesn't make a difference, one turn or two, I always only use one loop around the eyelet. Earlier, a very long time ago, more than 7 years ago, I used an end seal as Lauri recommends. Then, when I started using crimping pipes, I realized that it was very simple and quick, after which I stopped using Kevlar or copper wire just to save time. I constantly change the length of the lines, the diameters of the lines, the materials of the lines to find the best option, which leads to a very large number of end closures. With such a volume of work, I am saved by the crimp tubes that have worked perfectly for me for 5 years and more than 2000 flights.
Regards
Ruslan