Originally Posted by loNslo
Pretty sure the scarph has to be much longer than 3:1, perhaps more like 6;1 or 8:1.
And, in this case, it's probably easier to replace the spar. On yours, you did the right thing by putting the scarph out at the end.
You would think so, and so would I, but I looked it up in my official Aircraft Woodworking book and it in fact says 3:1 and has a diagram that looks to be that scale, and more surprisingly says a spar can be spliced anywhere except for where a strut or landing gear attach. Frankly I don't like the thought of doing it in a real aircraft, but I do it all the time with my model planes when crashes break various parts, typically leading edges but other parts as well.
Plus, these beautiful scale models are flown pretty gently, at least in my hands, because they are such labors of love, and probably are pretty unlikely to come apart in the air unless the workmanship is very shoddy. The main point of failure is usually landing gear related, at least on my planes, partly because I think they are not designed for some of the fields we fly on or some of the less than perfect landings we make, or both.