VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.


Go Back   VAF Forums > Model Specific > RV-9/9A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 03-12-2014, 05:11 AM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,517
Default RV-9A and -7A stall testing with wing tufts

RV-9A
http://youtu.be/qeSoO3nXjjI

added as update
RV-7A
http://youtu.be/ECTCVgiBHjA
__________________
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 = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 03-12-2014 at 08:22 PM.
Reply With Quote
  #2  
Old 03-12-2014, 07:47 AM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
Default

Interesting Steve. It's doing it just as it was designed to.
You built a straight airplane.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
Reply With Quote
  #3  
Old 03-12-2014, 08:41 AM
PeteP's Avatar
PeteP PeteP is offline
 
Join Date: Jun 2011
Location: Chesapeake, VA
Posts: 219
Default Nice!

Steve - Nice job and a clean stalling wing. Thanks for the vid.
__________________
Pete (AKA Yoda)
Exempt but VAF 2017 Dues Paid anyway
Reply With Quote
  #4  
Old 03-12-2014, 09:58 AM
apkp777's Avatar
apkp777 apkp777 is offline
 
Join Date: Oct 2008
Location: Okauchee, WI
Posts: 2,054
Default

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)
__________________
Tony Phillips
N524AP, RV 9 (tail wheel)
Reply With Quote
  #5  
Old 03-12-2014, 10:44 AM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,517
Default 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.
__________________
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 = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
Reply With Quote
  #6  
Old 03-12-2014, 12:11 PM
cfiidon's Avatar
cfiidon cfiidon is offline
 
Join Date: Apr 2008
Location: Arizona
Posts: 657
Default

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
__________________
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."
Reply With Quote
  #7  
Old 03-12-2014, 02:31 PM
longranger's Avatar
longranger longranger is offline
 
Join Date: Mar 2007
Location: 45G, Brighton, MI
Posts: 1,921
Default

Quote:
Originally Posted by cfiidon View Post
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
I see in your signature you have an 8. By plan at least there's no washout in those wings.
__________________
Miles (VAF# 1238, Paid up as of 12/20)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on site

Construction Log
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.
Reply With Quote
  #8  
Old 03-12-2014, 02:55 PM
apkp777's Avatar
apkp777 apkp777 is offline
 
Join Date: Oct 2008
Location: Okauchee, WI
Posts: 2,054
Default

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.
__________________
Tony Phillips
N524AP, RV 9 (tail wheel)
Reply With Quote
  #9  
Old 03-12-2014, 04:41 PM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,517
Default 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."
__________________
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 = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 03-12-2014 at 04:49 PM.
Reply With Quote
  #10  
Old 03-12-2014, 05:56 PM
David Z David Z is offline
 
Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 771
Default

The idling prop will be blocking a good portion of the airflow over the wing root as well.
__________________
RV8
Empennage Passed Pre-close Inspection
Wings mostly done
Fuselage deburring and dimpling. So many holes
83126
Dash 8 day job is financing the RV8
Donation till September 2022
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 12:51 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.