I've heard lots of talk about folks doing the "homebuilt" wind tunnel by attaching a model to the back of their pickup. I'm at about the point I'm ready for this. My goals would be:
1) To figure out approximate CLmax, with and without various wing fences.
2) To figure out the pitch moment of "zero moment" flaps and try to get "zero moment rudders" figured out.
3) To confirm that elevon deflection is zero at the expected point; that twist is correct.
4) To very roughly estimate drag of the configuration.
I know Reynolds number effects are always a factor for this sort of thing, but at least for the stall speed operations I'm not too worried. My vehicle will handle twice my stall speed if I take it to the salt flats, so I'd be at 2/3 actual reynolds number with a 1/3 scale model.
The two open questions in my mind (currently... there'll be more) are about structure and measurement.
1) If I just CNC mill the whole darn thing at 1/3 scale out of a piece of cheapish hardwood, will I be structurally okay? I'd much prefer to make this a cheap and easy experiment (and, importantly, easy to redo with a changed wing) that make it a structural exercise too.
2) What mounts do people use for this sort of thing? I'd imagine I need at least lift and drag load cells; is this plus a ball mount (so pitch and yaw can be set by eye during the test by servo controlled surfaces) the way to go, or should a higher-degree-of-freedom mount be used? Anything commercially available?
1) To figure out approximate CLmax, with and without various wing fences.
2) To figure out the pitch moment of "zero moment" flaps and try to get "zero moment rudders" figured out.
3) To confirm that elevon deflection is zero at the expected point; that twist is correct.
4) To very roughly estimate drag of the configuration.
I know Reynolds number effects are always a factor for this sort of thing, but at least for the stall speed operations I'm not too worried. My vehicle will handle twice my stall speed if I take it to the salt flats, so I'd be at 2/3 actual reynolds number with a 1/3 scale model.
The two open questions in my mind (currently... there'll be more) are about structure and measurement.
1) If I just CNC mill the whole darn thing at 1/3 scale out of a piece of cheapish hardwood, will I be structurally okay? I'd much prefer to make this a cheap and easy experiment (and, importantly, easy to redo with a changed wing) that make it a structural exercise too.
2) What mounts do people use for this sort of thing? I'd imagine I need at least lift and drag load cells; is this plus a ball mount (so pitch and yaw can be set by eye during the test by servo controlled surfaces) the way to go, or should a higher-degree-of-freedom mount be used? Anything commercially available?