At 08:45 AM 7/22/2006, you wrote: >My KR2 (built by others) was fitted with heaps of VGs under the >horizontal stab, on the fuselage prior to the rudder, on the landing >gear and in front of the canopy. A previous archive search suggested >that it lowers stall speed and if placed correctly has no speed >effect. There are none placed on the main wing (original aerofoil). >I don't understand why the previous owner wanted to lower the stall >speed of the horizontal stab, but not the main aerofoil...and why >the association with the rudder and canopy? Were they just VG crazy? >Any thoughts?
The vortex generators upstream of the tail surfaces will/can improve control authority at low speed by keeping the airflow attached to the elevator or rudder when they are deflected. As for the gear, canopy, and other non wing-type surface, the only reason to put them there that I can think of is that the previous owner did not know what he was doing. Tripping the flow from laminar or turbulent to separated in a controlled manner (which is what a vortex generator does) can sometimes reduce drag, but only if it is done correctly. A vortex generator is not the proper way to do this. I suggest that those can be removed and you will not notice any difference. Don Reid - donreid "at" peoplepc.com Bumpass, Va Visit my web sites at: AeroFoil, a 2-D Airfoil Design And Analysis Computer Program: http://aerofoilengineering.com KR2XL construction: http://aerofoilengineering.com/KR/KR2XL.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA Regional Fly-in: http://vaeaa.org
