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VG's to lower stall speed & T.O. &landing distances?
http://t18.net/thorpforum/viewtopic.php?f=3&t=7626		 Page 1 of 1
Author:  flyingfool [ Thu Aug 07, 2014 1:52 pm ]
Post subject:  VG's to lower stall speed & T.O. &landing distances?
Has anyone tried Vortex generators to lower stall speed and reduce runway landing and take off distances?

Would they even help?

I understand that VG's are ugly but they seem to work really well and are said to not lower top end speed too much if at all.
Author:  Jim Mantyla [ Thu Aug 07, 2014 8:34 pm ]
Post subject:  Re: VG's to lower stall speed & T.O. &landing distances?
I have VG's on my outer wing panels. My stall was quite abrupt with no warning prior to adding the VG's and stall strips. I haven't noticed any speed reduction but when in ground effect and floating I now have full aileron control. The stall is also more Stinson/Cessna like in nature.

I don't think they lower my takeoff distances. The Thorp gets up and flying real quick. I brought my new hangar mate up for a ride and his comment is that it handles much like an F-5 with respect to responce, that he used to fly with the Canadian Air Force.

Jim
Author:  SHIPCHIEF [ Thu Aug 07, 2014 11:26 pm ]
Post subject:  Re: VG's to lower stall speed & T.O. &landing distances?
I added vortex generators & stall strips similar to Jim and my results are similar too;
I have 3/8" x 6" stall strips just above the leading edge of the center wing section airfoil. These are mounted with the outer end directly behind the propeller tip, as called out in the T-18 news letters.
The vortex generators I made were copies of the 'Hall' type.
http://www.hallwindmeter.com/vortex.php
I bent them up out of aluminum and stuck them on the wing with double sticky carpet tape. (use wax remover on paint first, or they will fall off)
I used 2 each per wing, in front of the ailerons. The first is 2" outboard of the outer wing panel attach join, the second 12'' outboard of the first. (I presume there is some outward span-wise flow in low speed flight.)
They are 10% back from the leading edge, measured over the skin.
The effect: The stall strips behave exactly as the news letters said, a testimony to the data they contain. The stall speed is not reduced by these strips, they simply warn the pilot with a nice stick shake about 3-5 MPH above stall speed. The vortex generators increase the effectiveness of the ailerons in the stall.
The vortex generators did not reduce the top speed of my aircraft by any amount that I could notice.
They do make low speed flight much more comfortable for me.
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