hambush

Thanks everyone for your helpful suggestions. I've been locked out of my forum account for the past week, which is why I haven't responded until now. I wish I'd known about WCL earlier! I'm too far down the road with this current project to do much about it. Maybe I'll do a version 2... However, in the process of reading up on WCL I remembered that it is possible to modify the models in the PicaSim simulator, or create new ones, so maybe I could use it to predict the performance. Luckily the sim can already simulate the full size model (Le Fish), so I created a scaled down version. The good news is that I can fly it (for some definition of "fly"); the bad news is that it is a bit exciting, as you all predicted! I'm hopeful that the simulator approach will be reasonably accurate. I've found the sim to be realistic for the Weasel (which I've flown in real life); I also found that a mini Le Fish where the weight was scaled according to WCL performed much closer to the full size model, which gives me some confidence in the simulation.

I should have asked this question before I started my project... I'm curious about how the aerodynamic performance of a design changes as you scale it down. Or rather, how do you go about maintaining a similar performance as you scale down? The relevant factors that I can come up with are: Wing loading Reynolds number My specific case is that I'm scaling down an existing slope soarer design to 50% of the original. I know that the wing loading will remain roughly the same, as the weight is going to be close to 25% of the original (and I can add ballast if necessary). If I want it to fly at roughly the same speeds as the original, then the Reynolds number will be 50% of the original. So, if the aerofoil used in the original has a similar performance across that range of Reynolds number, or I can find a different aerofoil that has a similar performance to the original but for the lower Reynolds number, then the wing should behave similarly. I feel I must be missing some important factors, but I've no idea what. Or it the problem that it is difficult to find an aerofoil that has similar performance at the smaller scale? Thanks!