TA-152 Washout.

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Soehlig

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Kinda toying with designing a TA-152 inspired aircraft. I was reading on the wiki page (not sure if that's a good start) that the TA-152 has 3 degrees of washout. Is this on about the right track? I appreciate any help or advice. Thanks in advance.
 

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Voidhawk9

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Sounds reasonable. It can be tricky to find such data, and it may not be applicable in your case anyway as presumably you will be using different airfoils at different Reynolds numbers than the TA-152?
 

Soehlig

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I looked up the NACA airfoil and tried to replicate it. I'm not sure if scale would have anything to do with it. This would be a smaller aircraft that is definitely slower (which I guess would be a lower Reynolds number??).
 

Tiger Tim

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Just thinking out loud here but a scale warbird touring motor glider would be a neat machine. Obviously a TA-152 comes to mind but also a BV-155 or even a Westland Welkin if you want a twin. Any late WWII high altitude fighter, really.
 

Riggerrob

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We must caution you against exactly copying the TA-152 wing because it was developed from the Focke-Wulf 150 that had a nasty stall with flaps up. FW.190 stalls tamed down when flaps were lowered.
At a minimum, thoroughly review your TA.152 wing drawings before cutting any aluminum, foam, wood, etc.
 

llemon

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The Ta-152 had non-linear geometric twist. Something like the outer 20% of span being a constant angle.

The nasty stall of the wing was likely a side effect of the 23 series airfoil.
 

BJC

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The nasty stall of the wing was likely a side effect of the 23 series airfoil.
Welcome to HBA.

Use the search function; we have discussed the 230XX airfoil stalling characteristics at length. Botton line: all the declarations about its “nasty stall characteristics” simply are not valid.

Also look at the airfoil usage data base. You will see that lots of highly successful aircraft use the 230XX airfoil.


BJC
 

Norman

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all the declarations about its “nasty stall characteristics” simply are not valid.
Yes BUUUT that's because 3D planform effects can override 2D airfoil effects. The Ta-152 wing planform is NOT helpful because it tapers (a lot) in both chord and thickness, both of which aggravate tip stall. The only saving grace of the wing geometry is the washout which, as llemon stated in post #7, is nonlinear and probably doesn't go far enough for a general aviation machine.
 

BJC

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Yes BUUUT that's because 3D planform effects can override 2D airfoil effects.
Yup, real world; I’ve never yet seen a wing with an infinite span.
The Ta-152 wing planform is NOT helpful because it tapers (a lot) in both chord and thickness, both of which aggravate tip stall.
Yup, planforms do have significant effects, especially those that result in a tip with a sharper LE radius operating at half the Rn of the inboard wing.


BJC
 

Soehlig

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I've spent about a month and 50 iterations trying to get the lines right on this project. Shooting for a 75 percent scale D9 now. By scale I should say strongly influenced, but not a direct scaled version. Using a NACA 0010 for the vertical stab and elevator, 23015 wing root, 23009 for the wing tips. Still working in XFLR before I try to put the wings on the design.
 

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Victor Bravo

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There are also several other airfoils in the world than the 23 series, and aircraft designers are thankfully aware that there is in fact no magic law which mandates the same airfoil at the tip as the airfoil at the root or mid-span. Twist is only one of several things that you can adjust and alter to arrive at a desired stall outcome.
 

pylon500

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Not totally familiar with the FW control systems, but a lot of German gliders of the day would set the controls up such that as the stick came back, the ailerons would lift to increase washout. The only time you really need washout is when flying slow or pulling G.
This may not be advisable if using frise ailerons...
 

BJC

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... a lot of German gliders of the day would set the controls up such that as the stick came back, the ailerons would lift to increase washout. The only time you really need washout is when flying slow or pulling G.
I changed the rigging of the ailerons on my Sportsman from matching the LS(1)-0413 airfoil to having the TE up about 1/2 inch. I gained 2 knots top speed.


BJC
 

Norman

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I changed the rigging of the ailerons on my Sportsman from matching the LS(1)-0413 airfoil to having the TE up about 1/2 inch. I gained 2 knots top speed.


BJC
By doing that you remove some aft camber which tends to move minimum drag to a lower CL, it's a camber effect not a washout effect. That's the idea behind trim flaps which are used on some sailplanes to widen the speed range.
 

Victor Bravo

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trim flaps which are used on some sailplanes to widen the speed range.

Oh heck no, please don't call them trim flaps, that's not nearly cool enough.

Call them "Adaptive Performance Dynamic/Active Camber Changing" or something really macho like that - we have pretty fragile egos you know.

(Actually, Dr. Iscold has really done all that high-falootin stuff with his Nixus)
 

wsimpso1

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There are also several other airfoils in the world than the 23 series, and aircraft designers are thankfully aware that there is in fact no magic law which mandates the same airfoil at the tip as the airfoil at the root or mid-span. Twist is only one of several things that you can adjust and alter to arrive at a desired stall outcome.
But I still would not taper the 23015 down to a much smaller chord and to 23010, even with 3 degrees of washout. This is tempting fate on a couple different levels. If you just have to hold planform and use 23015 at the root, hold the 23015 to the tip to give yourself a better chance at decent stall behavior.

What material set are you planning for this bird?


Billski
 

Norman

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Agreed. There's potential for trouble here.
A different airfoil entirely at the tip may be the way to go - no-one will notice.
Well... I would notice but I'm a geek. The 230 mean line produces a pretty distinctive double chin that is pretty noticeable to even casual observers looking at the tip but, yeah, if they didn't know that "nobody" would notice. I do agree though that a different airfoil at the tip would make for a better handling wing. There are several airplanes named "Provost" in the UIUC database that used 230xx root and thinner 44xx tip. This type of wing absolutely must have twist to get zero aerodynamic washout because the 44s have much lower zero lift angles than the 230s. This makes for a later stall of the outboard panel with no performance penalty. In fact it may be a slightly higer performance wing than all 230xx airfoils because the 44xx have batter L/D than the 230s. Since the last 5% of the span is basicaly stalled all the time anyway you could make a tip faring that reproduces the underside of a 230xx if that little cosmetic detail is really important.
 
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