Sbach Tip Stall and Vortex Generators

The Sbach and I have a long rich history of tears, pulling of hair and gnashing of teeth, mostly due to its unstable wing at low speeds and its strong tendency to severly tip stall into an unrecoverable death spin.

When I took the old 30cc Sbach wing and adapted it to the MX2 fuse creating the MX-Bach, it was necessity, not a love for the Sbach wing, despite its sexy shape, that made me do it. To address the tip stall, I sought a way to keep the lifties under the wing tips for as long as possible and to allow a more gentle stall. And voila, I discovered Vortex Generators.  Here is a great presentation on the concept, a video of experiments by an RC engineer.

I didn't, and don't, have the data nor the gumption to do all that math, so I just made some using L-shaped styrene strips, and installed then where I thought they should go, about 5-8cm back from the leading edge.  It's all described here.  I knew they would be tall enough, just picked a length, decided a V shape was nice looking, and stuck the buggers on. It actually worked! The MX-Bach has only flown a couple of times with the VGs, but she no longer shows the stall tendencies she used to. I think flying her at 10S made her a bit underpowered, so am very excited to be converting her to 30cc gas!

So as I prepare to build yet another Sbach, I am considering putting the vortex generators on her too. I will use the same guess work and install them similarly. I still have the L styrene strips. I think she is going to be an amazing flier!