| On the last trip to the field it was a flat calm, very unusual for our Redmarshall site.
As expected the take off run was considerably longer than on previous occasions, although the grass is kept short, at scale it is still the equivalent of taking off in a field of mowing grass so there is plenty of rolling resistance. If the model is taking off into a 5 mph wind then the airspeed is 5 mph faster than the ground speed; it even has an air speed of 5 mph when standing still!
What did surprise me was the rate of climb, or lack of it, once the model left the ground. In fact by the time it had gained sufficient height to make a turn I was quite concerned that it was so far away that orientation would soon become a problem. This is where I made an “error of judgement”; I turned the model to the right. The model lost some height executing the turn and was now only just visible above the hedge line, then I realised in the direction the model was now travelling the ground was rising at a gradient about the same as the models rate of climb so there was insufficient height to make another turn, so I closed the throttle and set the model down in the middle of the barley field.
When I got the model back I tried adjusting the needle valve just in case the engine wasn’t quite “on song” but it had no effect. I tried again; this time I was better prepared and had a successful flight but I’m going to try a smaller diameter prop to increase the engine revs, hence the maximum air speed, because although the model flies OK it is obviously marginal.
I’ve ordered an APC 15x4 but I’m going away in the caravan for a week so it’ll be after that before I can test it; watch this space! |