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09-27-2012, 05:09 AM
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Join Date: Apr 2006
Location: Martinsville, IN
Posts: 470
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using 20 degrees flap for departure
Hello. My runway has a slight raise in it at about 900 ft. I lift off, solo at 60, come off the ground a bit, then settle back down a bit due to the hump, which is a little "unsettling". This is with 10 degrees. Going the other way is about 1200 feet before the raise, and is non issue. I don't want this to happen on a windy crosswind day, especially with passenger. I have not experimented with 20 degrees flaps as of yet. I'm 160 lyc fixed pitch metal.
Surfaceasphaltt. Your advice please. DM
Last edited by drmax : 09-27-2012 at 05:13 AM.
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09-27-2012, 06:19 AM
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Join Date: Aug 2007
Location: Carrollton, GA
Posts: 313
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I would suggest trying 15 degrees of flaps first and see how that works. I use this off our 2400' grass strip with a 150hp Lyc fixed pitch, and seems to work well. I have no data to back it up, but 20 degrees seems like more drag than lift...my opinion only.
__________________
Jim Brown
RV6, Christen Eagle II(Sold)
ATP, CFII, A-IGI, A&P/IA
Carrollton, GA
Lyon?s Landing
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09-27-2012, 06:46 AM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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maybe try short field t/o procedure to get airborne before the "bump" in the runway.
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09-27-2012, 06:50 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Two options, the first is don't climb after you lift off. Fly it in ground effect, and inch off the ground, until 65, then rotate and accelerate to your desired climb speed. That won't take very long or take up more room.
As for the flap setting, I lower the aileron and drop to flaps to match them. That gives you 15* +/- which works out to about 1/2 flaps in the -9.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Last edited by N941WR : 09-27-2012 at 07:49 AM.
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09-27-2012, 06:54 AM
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Join Date: Jan 2007
Location: Stuart, FL /Hartford, CT/Virgin Gorda,BVI
Posts: 3,122
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try lifting off at 65. this may give you more ummph so you dont settle back down. follow the hump in ground effect. 
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TURBO YES =VAF= Payed Jan2019
Ed D'Arcy
RV6-A 5,200+ hrs, R-44 1,600 hrs, Helicycle 320 hrs, gyro sold,35,000 miles flown in 2015 
Stuart, Fl / S WINDSOR,Ct / Virgin Gorda, BVI - under major repair from hurricane damage
VAF #840 EAA AOPA FAC FABA QB SPA
addicted pickle ball player
https://i.postimg.cc/tn3h4svg/IMG-3101.jpg
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09-27-2012, 07:13 AM
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Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
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As has been stated above, 15° is optimum for max lift and min drag. I've done experiments with all flap settings and 15° works out best.
The aileron "down" travel is set to 15° for this reason. It also makes it convenient to set the flaps if you have electric. Just align the flaps with the "down" aileron and you're set to go.
I actually use 13°, but that's because my manual flaps have 13, 26, and 39° notches.
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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09-27-2012, 07:24 AM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Quote:
Originally Posted by Mel
As has been stated above, 15? is optimum for max lift and min drag. I've done experiments with all flap settings and 15? works out best.
The aileron "down" travel is set to 15? for this reason. It also makes it convenient to set the flaps if you have electric. Just align the flaps with the "down" aileron and you're set to go.
I actually use 13?, but that's because my manual flaps have 13, 26, and 39? notches.
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This is the proper way to set your flaps, it will help you pop off the ground a little quicker. But be advised it will also retard acceleration once you leave the ground. As soon as you are a few feet above the ground begin retracting the flaps so the plane can accelerate promptly.
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09-27-2012, 07:48 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by Sam Buchanan
This is the proper way to set your flaps, it will help you pop off the ground a little quicker. But be advised it will also retard acceleration once you leave the ground. As soon as you are a few feet above the ground begin retracting the flaps so the plane can accelerate promptly.
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I disagree with this.
Don't be in a hurry to retract the flaps. Let the plane accelerate with the flaps down so you don't settle back on the ground. Once you have established a positive climb rate, well above the flaps up stall speed, then the flaps should be retracted and either Vx or Vy established, depending on the conditions/needs.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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09-27-2012, 07:55 AM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Quote:
Originally Posted by Sam Buchanan
This is the proper way to set your flaps, it will help you pop off the ground a little quicker. But be advised it will also retard acceleration once you leave the ground. As soon as you are a few feet above the ground begin retracting the flaps so the plane can accelerate promptly.
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Quote:
Originally Posted by N941WR
I disagree with this.
Don't be in a hurry to retract the flaps. Let the plane accelerate with the flaps down so you don't settle back on the ground. Once you have established a positive climb rate, well above the flaps up stall speed, then the flaps should be retracted and either Vx or Vy established, depending on the conditions/needs.
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Bill, I don't think we disagree.
My RV-6 (and I suspect most RV's) will establish a positive climb rate above stall speed a few feet above the ground. 
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09-27-2012, 08:01 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by Sam Buchanan
Bill, I don't think we disagree.
My RV-6 (and I suspect most RV's) will establish a positive climb rate above stall speed a few feet above the ground. 
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Yep, I agree. Even when I had the small (135 hp) engine in my -9, it would jump off the ground and rotate to a positve rate of climb very quickly. With the 180+ HP engine, it just does it faster.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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