RE: .074 MARAUDER !!!
Digger, This stuff is the green colored fishing line that looks like sewing thread. It's either called Spiderline or Spiderwire..I forget.
In a perfect world control line planes should never have the lines go slack...but it happens. When it happens you need to get on your horse quickly and get that line tension back. The standard steel cable sizes for the various weights and classes of aircraft is usually up to the task in this case.
But.....if any C/L plane does a severe turn into the circle and then back out to the end of it's leash, I've never seen a full recovery from that. Usually 1 or both cables will snap if that happens.
You try to get away with an adequate safety margin, but not overkill. The weight and drag of the lines is a damper on performance. So far I've had quite a few flights with this line at the 52 foot length but only time will tell if this weight of line will be acceptable. This plane is actually pretty heavy for a .074 powered model and I should try to figure out how much strain is exerted at whatever speed it is flying at.
I just took a guess that these lines would be up to the task to withstand "normal" flight, which should take into consideration the occassional slack lines episodes.