Washout built into the wings of the Ta-152H

[Broncazonk]

I can’t find a description of the washout built into the wings of the Ta-152H in either the Harmann text or the Hitchcock. (I’m not saying that it’s absent, I just can’t find it in either text.) I can’t find a description of washout in the Nowarra or Grinsell texts either. A description of washout may appear in the Krzyzan text, but I don’t read Polish so I don’t know.

Here is a description of the washout built into the wings of the Ta-152H written by the National Air and Space Museum—please read it carefully because I believe it is incorrect.

“Kurt Tank chose the same workhorse Jumo 213 powerplant used in the Fw 190D. For the Ta 152H, he selected an uprated version, the Jumo 213E, equipped with a 2-stage, 3-speed mechanical supercharger and MW 50 engine boost. The MW 50 system used methanol-water mixture to boost engine output from 1,312 kw (1,750 hp) to 1,537 kw (2,050 hp) for short periods. Because of aluminum shortages, Focke-Wulf made the wing spars from steel and built the rear fuselage and empennage. The wing contained two steel spars. The front spar extended slightly beyond the landing gear attachment points but the rear spar spanned the entire wing. The wing twisted 3° from the root to the flap-aileron junction. This 'washout' prevented the ailerons from stalling before the center section. This allowed the pilot to maintain roll control during a stall.. Armament consisted of one 30mm MK 108 cannon firing 90 rounds through the propeller hub and one 20mm MG 151 cannon firing 150-175 rounds from each wing root.”

http://airandspace.si.edu/collection...m_A19600317000


And here is another description that doesn’t sound correct either:

The aircraft had an increased wingspan compared to the previous FW 190 design, as a further accommodation towards better high altitude performance. Due to the war's impact on aluminum availability, the wing was built around two steel spars, the front extending from just past the landing gear attachment points, and the rear spar spanning the entire wing. The wing itself was designed with 3° of washout, from the root to the flap-aileron junction, to prevent the ailerons from stalling before the center section of the wing. This design allowed the pilot to maintain roll control during a stall and extreme flight envelope maneuvers.

http://warthunder.wikia.com/wiki/Ta_152_H-1

If I’m not mistaken, in actuality, there was 3° of washout (three degrees of downward twist) built into the wings beginning at the flap-aileron junction that extended to the wing tips—not from the root to the flap-aileron junction. Washout is described here: http://en.wikipedia.org/wiki/Washout_(aeronautics) and http://www.propdesigner.co.uk/html/w...nd_washin.html

I don’t think the Ta-152H could become airborne with 3° of washout built from the root to the flap-aileron junction.

Would the experts on the list please provide some clarity on this?

Thank you,

Bronc

[stephen f. polyak]

Simply, if I understand your question…. The wing's operating range of angles of attack from initial lift to stall is greater than 3 degrees. Having the washout run from the root to the aileron junction does not prevent the full wing (all airfoil sections) from producing lift when sufficient speed is reached to takeoff. Because of washout, when the plane is flying, the relative angle that the wing operates at decreases from wing root to wing tip. Thus, the inboard region of the wing will reach its stall angle before the outboard region. As the inboard region looses lift due to a stall, the aileron, being part of the outboard region which is not at stall, continues to deliver roll control. Without washout, on reaching the stall angle, the entire wing would loose lift and aileron effectiveness would be seriously degraded.

[bearoutwest]

My interpretation of the text is that the washout is built into the structurally rigid inner wing section and remains constant for the outer wing section with the control surfaces, i.e.
a) washout goes from 0 degrees (relative) at the wing root, to -3 degrees at the flap-aileron junction;
b) washout remains at a constant -3 degrees across the outer wing supporting the aileron hinges.

I gather that the more solid (or rigid) inner wing is more suitable to manufacture the rib structure alignment to provide the downward twist. The outer wing with it's more slender section being (in a relative sense) more difficult to manufacture the appropriate rib alignment, with the added possibility of interference with the aileron hinge connections.

The inner wing washout means it goes from 0 to -3 degrees across the span between root to flap/aileron junction, so not -3 degrees all the way along the inner wing. As for ability to take off - well at take-off rotate speed, you may need to pull back extra on the stick to generate 3 degrees up angle on the wing, that means the inner wing is now aligned at +3 degrees (at root) to 0 degrees (at flap/aileron junction) to the direction of travel, regulation wing lift coefficients in effect from now onwards. Continue pulling back on the stick to generate best rate of climb wing angle, etc, etc.

Regards,
...geoff

[Graham Boak]

I agree that it is normal to expect washout near the tip, because that is the part of the wing that will twist most and hence otherwise stall first (not the wing overall, just at the tip). This is unsatisfactory because any asymmetry will result in severe un-demanded roll. Building in the washout inboard may end up with the same result overall, but does seem to be aerodynamically inefficient. If it is structurally more efficient in this case, then it can be regarded as an example of the trade-off between different factors in every design.

[Pilot]

The fact that it flew, mean it can be airborne. This washout helps with higher angle of attack and they are for sure included in high altitude flight envelope (air is less dense there). During the airfoil test in wind tunnel, result are made and diagrams for the various angle of attack and various speed and in most airfoil allow negative and positive angle of attack (which result in lift change).

[Broncazonk]

I'm not contesting whether the Ta-152H flew or not! Of-course they did. Kurt Tank and his designers obviously put some very sophisticated aerodynamic engineering into this wing design, and I'm just trying to understand it, that's all.

The two web-based descriptions of the washout incorporated into the design of the Ta-152H's wing are the exact opposite of the standard definition of structural washout. To begin with, I'm just trying to determine if these descriptions are correct.

Bronc

[Broncazonk]

Originally Posted by bearoutwest

My interpretation of the text is that the washout is built into the structurally rigid inner wing section and remains constant for the outer wing section with the control surfaces, i.e.

a) washout goes from 0 degrees (relative) at the wing root, to -3 degrees at the flap-aileron junction;

b) washout remains at a constant -3 degrees across the outer wing supporting the aileron hinges.

The inner wing washout means it goes from 0 to -3 degrees across the span between root to flap/aileron junction, so not -3 degrees all the way along the inner wing.

So yes, this does make sense! (It took a couple of days for me to understand what you were saying.) The downward twist of the wing arrives at -3 degrees at flap-aileron junction, and then the twist was maintained at a constant -3 degrees throughout the aileron section to the tips.

Interesting.

I wonder what the gradient of the twist was?

Thanks!!

Bronc

[Tony Kambic]

NASM Ta152 wing at Garber.

[drgondog]

The FW 190D-9 and FW 190A had a Positive angle of 2 degrees at the root with constant wash out to the 80% semi span point at which point the angle was Zero, thence no further twist to the tip. I don't have access to the Ta 152 data.

reference - P. Gross "Die Entwicklung der Tragwerkkonstruction Fw 190", Bericht 176, der lillenthal Gesellschaft, 2 Teil, January 1944.

This is a unique design for wings without leading edge slats, in that the twist did not continue out to the tip chord. This combined with post war analysis suggesting that the Fw 190 wing was less stiff re: torque which could result in an abrupt stall in high G/high AoA maneuvering.

[drgondog]

Originally Posted by Broncazonk

So yes, this does make sense! (It took a couple of days for me to understand what you were saying.) The downward twist of the wing arrives at -3 degrees at flap-aileron junction, and then the twist was maintained at a constant -3 degrees throughout the aileron section to the tips.

Not likely. If the Ta 152 wing followed the Fw 190 and 190D philosophy, the angle of the airfoil chord relative to the vehicle axis at the root was a Positive 3 degrees, then twisting negatively spanwise from there

Interesting.

I wonder what the gradient of the twist was?

Thanks!!

Bronc

Constant, linear decrease from root incidence of 3 degrees to zero. Again, if similar to FW 190 series, the twist would reach 80% semi span to reach zero.

The purpose of the twist is to control the spanwise lift distribution and stall characteristics.