What length lines?
You need to decide on a line length. Rule 1 permits any line length, but there will obviously be a range of lengths within which your model will perform best. The longer the lines that your model will safely fly on, the greater will be the time difference between your fast and slow runs and therefore the higher will be your final flight score. Unfortunately, the shorter the lines, the easier it is to make a successful arrested landing! Hence line length is invariably a compromise. If your engine is between .25 and .40 cu in, a line length of about 50ft should be quite workable for both learning and competition. With a bit of luck, you’ve already got a set of 50ft lines anyway. If you’ve got two sets (but they must be exactly the same length), then you won’t even need to make up your third throttle line, will you?
Once you can fly a Carrier sortie confidently at this radius, you can try longer lengths. Some pilots even carry several line sets of different lengths to suit different wind conditions. If you’ve just started flying Carrier and your model seems to be going alarmingly fast and/or pulling uncomfortably hard, don’t forget that you can always go slower without making up longer lines by either using a richer needle setting or fitting a larger prop or putting the normal prop on backwards, until your confidence increases. Don’t worry – it will!