SonexBuilders.net

Hi all,
Question for all people flying;
Has anyone installed vortex generators on your aircraft?
1) model of sonex aircraft
2) your own design or from a company
3) material used/ attachment method
4) on wings or tail or both?
5) cost?
6) performance difference?
7) worth time and effort?
WaiexN143NM
Michael

I've always viewed VGs as a way to deal with a wing that stalls too fast and has bad handling at slow speeds. I've not found that trait in my Waiex. It handles every predictably and controllable right down to as slow as I want to fly it.
What problem are you trying to address?

Hi john,
Was just surfing the net on sonex stuff, happened to run across this posting from klaus in germany.
Google stol speed vortex generators sonex and see his posting w performance specs. Have seen a few pics of sonexs w vortex generators , just interested in any performace gains.
WaiexN143NM
Michael

What a surprise...someone who's selling something tells you how great it is.

Hi charlie,
Yep, was just interested if anyone else had experimented w vortex generators, post from klaus on the stol speed testimonials. Was curious to know if his claims of t.o. Distance , climb rate, stall speed , and cruising speed are to be believed.
WaiexN143NM
Michael

An improvement of 15 km/h in cruise from something that can only increase drag is too good to be true. Most of airplanes that report an increased cruise speed with VGs do so by removing slats at the same time.

His low speed numbers are interesting, but like you, I'd be interested in hearing someone else's report since this one is so suspect.

IMHO, the NACA 6-series airfoil that the Sonex uses is not like the airfoils used by Cessnas or many of the STOL aircraft out there. Therefore it is less-likely to receive much of a benefit from VGs (or, at least less of a benefit than many airplanes).

Here are a few articles for reading:

https://en.wikipedia.org/wiki/NACA_airfoil#6-series

http://web.stanford.edu/~cantwell/AA200_Course_Material/The%20NACA%20airfoil%20series.pdf

Vortex Generators (VGs) are designed to do two main things: (1) Avoid separation bubbles where the airflow detaches from the wing, and (2) Force a transition to turbulent airflow. While laminar airfoils _can_ have separation bubbles, putting VGs on - forcing turbulent flow all the time at that location - has the potential to reduce performance or cause as many problems as it solves; if you're taking laminar sections and turning them into turbulent flow (with higher associated drag). I think this may be especially true given that the NACA 6-series airfoils were designed to provide low drag via laminar flow at typical cruising speeds/lift-coefficients. In this case, the VGs are essentially working against one of the main design factors behind the airfoil!

Besides - if you want a STOL aircraft, there are plenty of fine kit aircraft out there that will do the job better than the Sonex ever will. The Sonex has a role, and it performs its mission just fine; there's no need to jam a square peg into a round hole.

--Noel

A local weight shift trike instructor installed VG generators on his rig. Says they improve handling at stall and increase cruise. They look like rubber stoppers stuck on the fabric. I trust his claims, but doubt it is universal to all aircraft.

Hi all,
Yep, was just reaching out to see if anyone had some real world experience w the vortex generators. I had seen a couple of pics of sonexes with them, and then saw the post from klaus.
Noel, in fact we are building a zenith 750 cruzer, for the arizona country backstrips . Will try some vortex generators after we get it flying, try to get some of the stol 750 performance without the drag of the slats. Bigger tires too.
WaiexN143NM
Michael

There was a guy (Bob)in Red Bluff several years ago, long time flyer and proud owner of his Sonex purchase. He subsequently sold it when life changes moved him too far from his airport. After owning it about a year or so, he bought a set of Vortex and applied them, tested, moved, tested, moved them again, tested. If I recall correctly he spent more than a dozen hours testing and his conclusion was that the Vortex did NOTHING to improve any of the aspects of the Sonex wing. I don't recall the exact specs or all the things he did, but he had previous experience with Vortex on some STOL planes led me to believe that pursuing Vortex on the Sonex was a waste of time and money.