Vortex Generators

[NX-687]

Tried some 50mm triangular VG's set at 45 Degrees to airflow, on my 3D foamy, wing
They slowed the model some , but the thing I noticed most was a pitch up both up right and inverted , aileron effectivness was about the same
These are big pieces on the wing , my CG was right back ,and maybe these things help push the CG further back , In not rapt with them , so they are coming off, about 12 off of them

Lighter battery will get me where I want to go, wider ailerons will get me a faster roll at low speed and also increase the wing area at the same time , Im hoping

[NX-687]

I wasnt really fair to my Very Gruesomes, the model still pitches up some under power,,, as the CG is well back , but the vague flying has disappeared now the VG's have , light batt taking it to 12.8 from 15,4 AUW will be super, cant wait

[macboffin]

Interesting experiment! I guess that vortex generators to re-energise boundary layer are really only valid for thin sections over two feet chord, at speeds around 80 knots plus. They were used on the Rutan Varieze foreplane, a laminar flow section, to cure a problem due to rain beading on the surface, killing lift and causing nose down ; turned out the easier fix was to go to a matt surface instead of highly polished, so that water would sheet instead of beading.Since foamies usually flat plate section, can't see any advantage, experiment would seem to confirm that.

[Brandano]

on something in the reynolds range of the Varieze foreplane the best solution would be not to use a laminar flow profile :)

[BMatthews]

50 mm? You are saying that you stuck some 2 inch Doritos onto your wing? Those are WAYYYYYY too large to do the job. All you did was add a lot of drag and help kill some lift.

Vortex generators for a typical 3 foot span foamy would be more like 5 to 7 mm and you'd use about 10 or 15 per wing panel. They would also need to be close to the leading edge to avoid being blanketed by the separation bubble that forms on a flat plate with even only a few degrees angle of attack.

[macboffin]

on something in the reynolds range of the Varieze foreplane the best solution would be not to use a laminar flow profile :) Thats for sure! The fix was for those planes already built and flying. One guy had the experience of going very nose down whilst passing through cloud, lost about three thousanf feet before the canard dried out and control returned.Was written up in "Sport Aviation" at the time. Scary!

[NX-687]

50 mm? You are saying that you stuck some 2 inch Doritos onto your wing? Those are WAYYYYYY too large to do the job. All you did was add a lot of drag and help kill some lift.

Vortex generators for a typical 3 foot span foamy would be more like 5 to 7 mm and you'd use about 10 or 15 per wing panel. They would also need to be close to the leading edge to avoid being blanketed by the separation bubble that forms on a flat plate with even only a few degrees angle of attack.

And the other input
Yes drag is good, it slows the model , but yes seemed to kill the lift a little and had a vague feeling I didnt like somehow
Will try your tiny's Bruce, each set 45 degrees to airflow
Indoor is the place to watch , those planes are magic

[NX-687]

Wing mounted aerodynamic device worked very well,
just one on one side of the wing , its full of gooey chemicals and took 2ozs off a 15 oz model , from now on I am down thicknessing my depron from 6 to 5 , 3 maybe going too far and maybe trying that detal floss reo method to get ridgidity, it lands more like a feather now , instead of a slapdown , also using my motor as an aerodynamic device , I can down weight , there too ,,,as I have too much vertical , kind of silly.
Half an ounce off there will mean a lot too