Vortex Generators

I finally bought some vortex generators. I got them from Landshorter. He had them on eBay and I won them for $90. We'll see if this is a get what you pay for type of situation or not.

When I contacted them before bidding, they said that RV-4 templates are available. However, after I won them I was sent a generic template with intstructions on how to locate them on any airplane. The instructions are plenty clear though. So if you're considering them just be aware of that.

I'm going to document installation and my observations of what these do for my RV-4 in this thread. So first things first. In the installation instructions it says they need to be installed at the location which is 10% of the chord of your wing. What I would like to know from anyone here is if they have determined this already. Ideally I'd like to know a distance from the butt joint on the top of the wing between the leading edge skin and the top skins. I'm going to go measure and find it for myself, I'd just like to see someone else's numbers to make sure I'm in the ballpark.

Scott,
I've done a bit of research on VGs and it would seem that 10% is pretty much accepted as the optimum position. So, if your chord is say 51 inches, then mount the VG's at 5.1 inches from the leading edge. It seems kind of forward, but the 23013.5 is not a laminar flow airfoil anyway so you are just adding energy into the airflow over the top surface to re-energize the boundary layer. The test that I have read on the "4" yielded a 3 knot reduction in stall speed with a strap-on, calibrated, articulated, pitot system. There was also a small reduction in cruise speed.

I will be interested in discovering what your results are. You will probably need to use GPS to verify results because the ASI readings are so far out at low airspeeds as to be meaningless.

Cheers, Pete

I'm going to use that GPS Wind Square website that's out there somewhere. I'll post a before and after on the cruise speeds as well as the stall speeds. I'm attaching them more for the fabled "stability in turbulence" I've been hearing about. If I can get rid of the fishtailing tendancy in turbulence I'll be happy.

Somebody did a major test on these a few months back. I remember reading the writeup on the web. For some reason I am thinking it was Terry Jantze, up in Canada....I'll go see if I can find the website, if you haven't already seen it?

I found the link MUCH easier than I had imagined (I had it bookmarked). Here's the link:

http://www.ontariorvators.org/pitot/pitot.htm

pop up VGs

I think what is needed are VGs that pop out when you deploy the flaps.

rv8ch said:

I think what is needed are VGs that pop out when you deploy the flaps.

Click to expand...

now we're talking ...maybe Van could copy the leading-edge slats off of a Helio Courier that droop below a certain airspeed...might get those landing distances down to under 100' at walking speed...no cruise penalty either.

I bought my vortex generators from Larry Vetterman and they came with complete paper templates for each wing. Each one had the precise angle and location for the VG. Two part cement was furnished and the instructions were very good.
I have to fly between two trees in order to get onto the end of our 1100' runway , so really like the lower stall speed and added stability at minimum speed. I can't look at the airspeed indicator at that point. My stall speed is lower and I can't distinguise any loss at top speed - anyway I won't cry if I lose some at the top end.( I have mine made - I don't have to impress anyone !!).
Bob Olds RV-4 , N1191X
Charleston,Arkansas