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Jason over at Univair recently asked me about the numbers I see after I installed a set of VGs on my 53 PA-22/20. I couldn't document much more than the angle of attack I see in level flight, no gps etc, but thought I'd post a picture here anyway. I've had them on there for close to 6 years, so I probably won't get any more details very soon.
I also have the Madras tips so they further confuse what the VGs can do for our planes. The airspeed indicator bounces around between not working at all and almost up to the scale. The 150 HP turning a 58" prop at just under 1900 RPM seemed to hold things steadily in the sky with pretty much all the way back controls.I could probably cross control things to the max, give it a lot more power, and get some more angle, but then we couldn't really compare future findings here.
Last edited by Jim; 01-13-2011 at 12:09 AM.
Reason: Added the picture.
Are you asking for some numbers from "before" and "after" VG's? I documented slow flight when I put them on both my planes, and could dig up the info, if anyone's interested. Jim
.........Are you asking for some numbers from "before" and "after" VG's?
The following is what Jason wrote to me.
.........Oh, I was asked by Mike to ask what kind of stall speeds and
landing speeds do you get with the vortex generators. We never hear any info
on the benefits of having them on and we were wondering.
Jason
Univair Aircraft Corp.
info@ univair.com
Since I rarely play with a gps, I really can't document much of what the VGs have done for me.
I've installed them on a PA20-135, and a PA22/20-150. The 135 weighs 1050 empty and the 150 weighs 1215. GPS three ways showed a 11mph reduction in stall on the 135 and 8 mph on the 150. I'm guessing the 165 lb difference accounts for the 3 mph.
Power off, 3000 ft msl, I thought the biggest advantage was increased aileron effectiveness at slow speeds.
Dave
D. Grimm's figures are very similar to my findings. Slow flight (holding altitude) with the 22/20-150 = no flaps-2000rpm 60 mph (7mph change); 1/2 flaps-1950rpm 61mph (3mph change); full flaps-2000rpm 52 mph (8 mph change). Power-on stall - full flaps breaks at 48mph (4mph change); Power-off stall - flaps up 60mph (2mph change), half-flaps - 55mph (5mph change); full flaps 52mph (7mph change and basically no stall).
The Colt was more dramatic. In slow flight, before VGs, I could hold altitude at 1900rpm but not at 1800 approx. 60mph. After VGs, it held altitude at 1700rpm and was showing just under 40 mph. With just me in the Colt, it won't stall- power-on or off. All of the mph figures that I trained with (concerning landings), I now drop by 10 mph. There were no changes on either plane to cruise speed.
I looked before I posted but I didn't have any on this computer. I'll post some later. It is a nice looking Colt that was recovered in the late 90s and the engine overhauled in 01.