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#1
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Washout?
I picked up a project that was supposed to be built with 1.5 degrees
of washout towards the end of the wings. The builder unfortunately built them without washout, because while his workmanship was actually quite good he was worried he wouldn't be able to match the wings and one would drop in a stall. Before I rebuild the wings, what disadvantages am I looking at keeping things as they are besides the whole wing stalling at once? Any other aerodynamical problems? And could I cheat a fix by using VGs on the outer part of the wing? |
#2
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Washout?
wrote in message ... I picked up a project that was supposed to be built with 1.5 degrees of washout towards the end of the wings. The builder unfortunately built them without washout, because while his workmanship was actually quite good he was worried he wouldn't be able to match the wings and one would drop in a stall. Before I rebuild the wings, what disadvantages am I looking at keeping things as they are besides the whole wing stalling at once? Any other aerodynamical problems? And could I cheat a fix by using VGs on the outer part of the wing? Or put a "triangle" shaped addition on the leading edge of the wing's root, to trip that portion into stall, first. That's all anyone is after with washout. Keep the outer portion flying, while the root is stalling. If it were me, I would probably do a bit of both! g Advantages of keeping the wing with no washout is that the whole wing will be lifting at cruise, instead of throwing away part of the outer wing's lift with added washout. -- Jim in NC |
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Washout?
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Washout?
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#5
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Washout?
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#6
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Washout?
On Sun, 23 Mar 2008 15:15:35 -0400, "Morgans"
wrote: wrote in message ... I picked up a project that was supposed to be built with 1.5 degrees of washout towards the end of the wings. The builder unfortunately built them without washout, because while his workmanship was actually quite good he was worried he wouldn't be able to match the wings and one would drop in a stall. Before I rebuild the wings, what disadvantages am I looking at keeping things as they are besides the whole wing stalling at once? Any other aerodynamical problems? And could I cheat a fix by using VGs on the outer part of the wing? Or put a "triangle" shaped addition on the leading edge of the wing's root, to trip that portion into stall, first. That's all anyone is after with washout. Keep the outer portion flying, while the root is stalling. If it were me, I would probably do a bit of both! g Advantages of keeping the wing with no washout is that the whole wing will be lifting at cruise, instead of throwing away part of the outer wing's lift with added washout. big john and morgans have it with the triangular strips. you just tape them on and keep shortening them until you have the stall chracteristics you need. then you replace the temporaries with permanent ones. make both sides identical. work out where the 3 degree angle of attack neutral point is on the leading edge and stick them there. Stealth Pilot |
#7
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Washout?
On Mar 24, 7:03 am, Stealth Pilot
wrote: On Sun, 23 Mar 2008 15:15:35 -0400, "Morgans" wrote: wrote in message ... I picked up a project that was supposed to be built with 1.5 degrees of washout towards the end of the wings. The builder unfortunately built them without washout, because while his workmanship was actually quite good he was worried he wouldn't be able to match the wings and one would drop in a stall. Before I rebuild the wings, what disadvantages am I looking at keeping things as they are besides the whole wing stalling at once? Any other aerodynamical problems? And could I cheat a fix by using VGs on the outer part of the wing? Or put a "triangle" shaped addition on the leading edge of the wing's root, to trip that portion into stall, first. That's all anyone is after with washout. Keep the outer portion flying, while the root is stalling. If it were me, I would probably do a bit of both! g Advantages of keeping the wing with no washout is that the whole wing will be lifting at cruise, instead of throwing away part of the outer wing's lift with added washout. big john and morgans have it with the triangular strips. you just tape them on and keep shortening them until you have the stall chracteristics you need. then you replace the temporaries with permanent ones. make both sides identical. work out where the 3 degree angle of attack neutral point is on the leading edge and stick them there. Stealth Pilot The planform of the wing has a huge effect on stall behavior. If this is a rectangular wing, like a Cub or Champ, washout isn't usually necessary since the stall will start at the root anyway. If it's tapered or elliptical, washout is necessary to get the stall started at the root. It will start around midspan otherwise, and aileron effectiveness at low speed is lost. Some aerobatic airplanes have tapered or elliptical wings with no washout, but they're not for the average weekend flier. The stall characteristics can be very abrupt to get quick snap rolls and so forth. Dan |
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Washout?
wrote in message
... The planform of the wing has a huge effect on stall behavior. If this is a rectangular wing, like a Cub or Champ, washout isn't usually necessary since the stall will start at the root anyway. If it's tapered or elliptical, washout is necessary to get the stall started at the root. It will start around midspan otherwise, and aileron effectiveness at low speed is lost. Some aerobatic airplanes have tapered or elliptical wings with no washout, but they're not for the average weekend flier. The stall characteristics can be very abrupt to get quick snap rolls and so forth. Even with washout, the Emeraude (elliptical planform - 23012 airfoil) will stall fairly abruptly. Like, at 50 you're flying - at 49 you're not. Rich S. |
#9
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Washout?
Rich S. wrote:
wrote in message ... The planform of the wing has a huge effect on stall behavior. If this is a rectangular wing, like a Cub or Champ, washout isn't usually necessary since the stall will start at the root anyway. If it's tapered or elliptical, washout is necessary to get the stall started at the root. It will start around midspan otherwise, and aileron effectiveness at low speed is lost. Some aerobatic airplanes have tapered or elliptical wings with no washout, but they're not for the average weekend flier. The stall characteristics can be very abrupt to get quick snap rolls and so forth. Even with washout, the Emeraude (elliptical planform - 23012 airfoil) will stall fairly abruptly. Like, at 50 you're flying - at 49 you're not. Rich S. That's a function of the wing planform - not the airfoil. |
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Washout?
"cavelamb himself" wrote in message
... Rich S. wrote: Even with washout, the Emeraude (elliptical planform - 23012 airfoil) will stall fairly abruptly. Like, at 50 you're flying - at 49 you're not. Rich S. That's a function of the wing planform - not the airfoil. That's what I said. The info on airfoil was for comparison with the "Hershey bar" RV wing - the same airfoil - different planform. Rich S. |
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