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03-12-2014, 04:11 AM
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Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
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RV-9A and -7A stall testing with wing tufts
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all
Simplicity is the art in design.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
Last edited by Steve Melton : 03-12-2014 at 07:22 PM.
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03-12-2014, 06:47 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Interesting Steve. It's doing it just as it was designed to.
You built a straight airplane. 
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RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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03-12-2014, 07:41 AM
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Join Date: Jun 2011
Location: Chesapeake, VA
Posts: 219
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Nice!
Steve - Nice job and a clean stalling wing. Thanks for the vid.
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Pete (AKA Yoda)
Exempt but VAF 2017 Dues Paid anyway
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03-12-2014, 08:58 AM
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Join Date: Oct 2008
Location: Schaumburg, IL
Posts: 2,053
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Yep, the -9 stalls with very little loss of aileron control. If you accelerate the stall you get get to extend past the ailerons and even get a bit of a tail stall. That one gets your attention, but still docile. Those of us/you that have stalled a C152 with wings out-of-rig will have a hard time finding a similar stall induced excitement out of the RV9
Thanks for the video. I'd love to seem more (approach, accelerated, departure, cross-control, tail)
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Tony Phillips
N524AP, RV 9 (tail wheel)
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03-12-2014, 09:44 AM
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Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
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my question
why does the wing stall inboard first? It's a straight wing with constant cross section.
I like it. excellent control at slow speed.
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all
Simplicity is the art in design.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
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03-12-2014, 11:11 AM
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Join Date: Apr 2008
Location: California
Posts: 652
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Can't speak for the -9, but if it is like every other wing I know about there is a washout in angle of attack as you proceed toward the tip. The inboard section has a higher angle of attack and stalls before the tips, allowing aileron control through the stall.
Don
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RV-8 QB Titan ECi 191HP XIO-360
WW200RV Dynon D180 HS34 AP74
GNS430 SL30 GTX327 PS8000B Uavionix Echouat
"Pilots are alchemists... we turn gold into lead."
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03-12-2014, 01:31 PM
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Join Date: Mar 2007
Location: 45G, Brighton, MI
Posts: 1,867
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Quote:
Originally Posted by cfiidon
Can't speak for the -9, but if it is like every other wing I know about there is a washout in angle of attack as you proceed toward the tip. The inboard section has a higher angle of attack and stalls before the tips, allowing aileron control through the stall.
Don
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I see in your signature you have an 8. By plan at least there's no washout in those wings.
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Miles (VAF# 1238, Paid up as of 2018)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on site
Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album
1955 Cessna 170B flying since 1982
'To get something you never had, you have to do something you never did.' -Unk.
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03-12-2014, 01:55 PM
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Join Date: Oct 2008
Location: Schaumburg, IL
Posts: 2,053
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I don't think any RV's have "washout" or "Twist", but I'd love to hear one of the smart guys here in VAF explain how the "Hersey Bar" wing produces the inboard aft stall that progresses outboard to the tip. I know it has to do with "spanwise" air flow that artificially lowers the stall speed at the tips, but for the life of me I can put it into intelligible words.
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Tony Phillips
N524AP, RV 9 (tail wheel)
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03-12-2014, 03:41 PM
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Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
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aerodynamicist (not me) says
"Because of the fuselage interference, the wing root is likely seeing a lower flow speed as flow wants to move away from the fuselage (transverse direction) towards the wing tip at the wing root. Therefore the axial flow velocity at the wing root is lower than the wing tip and that is why you are seeing separation at the root first. From the motion of the tufts, I see that when the inboard separates, the separation is from the LE all the way to the back (80-90% chord). Not sure what your speed was at those points, but I would imagine that this is a laminar flow separation starting at the wing LE. The solution to this could be as simple as putting a series of vortex generators (1-2 rows) to induce some turbulence and suppress the premature flow separation."
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all
Simplicity is the art in design.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
Last edited by Steve Melton : 03-12-2014 at 03:49 PM.
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03-12-2014, 04:56 PM
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Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 335
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The idling prop will be blocking a good portion of the airflow over the wing root as well.
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RV-8
Empennage Passed Pre-close Inspection
Wings mostly done
Fuselage is "in the mail"
83126
Dash 8 day job is financing the RV-8
Donation till September 2021
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