Here's another video that seems to suffer from the same sort of tip stalling issue.

http://www.youtube.com/watch?v=LTUoG...eature=related

It looks like the Ziroli crash could have been avoided with a little more airspeed. On takeoff they survive one tip stall oscillation and the nose lowers and it seems like all would be well if they had let the model accelerate some more. But the trees on the edge of the field obviously had the pilot's attention and he tried to pull the nose up before he had the right airspeed and we saw the result. On the second video it seems like a combination of an overweight model combined with the same tip stalling issue. Except in this case it occurs at the bottom of a dive pullout due to, presumably, the weight of the model and the small size combining to form a high G loaded stall.

A large amount of washout could possibly have avoided both of these instances or at least made the departures less radical and controllable. And without knowing the flying weight and wing loading it's hard to say but it's entirely possible that the first was overweight or at least on the edge enough that it required a more knowledgable hand at the controls to work towards avoiding the issues. He tries to climb away immediately on takeoff rather than letting it accelerate in the ground effect. A little more speed and letting the model reach trim speed and nose up naturally into a climb would have avoided this issue. Granted it was a first flight and the trim condition was unknown but in any event a little more speed would have helped. I don't know about you guys but models on grass fields often get bumped into the air when they are all too close to the ragged edge. And a heavy wing loading combined with a "scale" amount of power means that such a model needs a bit of time to reach a safe climb speed.

Added to this issue would be the likely use of large aileron deflections to try to pick up the wing. The adverse yaw and aileron induced stalling on such a critical wing shape flown at a near stall speed would make such inputs disasterous. This may have been a factor in both videos.

All in all an interesting thread and some excellent studies on all counts. It points out that the venerable DC-3 design may be a long lived one but that it's not without its foibles that pilots need to come to terms with before they can expect a long and healthy career.

A super light version will avoid SOME of the issues but the tendency will still be there. An initial takeoff that lift off and then flies level at first would be a wise precaution. As the model speeds up to a safe speed it should establish a natural climb with any stick pressure being held at the same setting that provided the level flight in the ground effect. If it doesn't want to climb out naturally then only give it some additional up pressure after a couple or three seconds. Given what we've seen in these videos and simulator studies this is how I'd approach it until the model's charactaristics are well known.