During a conversation earlier today, Arsenio Dev mentioned Project Morpheus. I recall occasionally seeing videos of the vehicle online in the last few years, but I hadn't closely followed its progress over the last few months. He recommended that I take a look at some of the videos related to tethered testing. I'm glad I did:
First of all, the music is amazing. Secondly, if you fast-forward to 2:10 or so (although you should really watch the whole thing), you'll see the test craft suspended from an overhead crane and anchored at four points to the ground. It's a great setup; the craft is constrained in all axes but still free to apply forces to the cables. I think a setup like this could be ideal for early GimbalBot tests, as I could insert gradual amounts of cable slack as the control algorithms improve. Maybe I could use a series of cheap spring-loaded scales to characterized the thrust vector produced by the craft. Either way, I'm still starting with static (fully constrained) tests.
Time to go watch more Morpheus videos; the archive is quite awesome indeed. 3D printed parts shipped today, so we're on schedule to start crudely instrumented experiments shortly.