FW190 vs. BF109: Turn Radius (2011)

[Stoney]

Isn't that low speed handling typically with enough flaps out to mitigate that condition?

No, not necessarily.  Typically, with flaps out, the flapped area of the wing will stall at a lower AoA than without flaps.  But if the tips stall close to or before the flapped area of the wing stalls, you can have the same issue, with the inboard part of the wing (with or without flaps) still flying, but with the wingtips stalled, and thus, very little aileron authority.  That's why some aerobatic aircraft have full span ailerons--so they retain aileron authority regardless of whether or not the wingtips are stalled.

[FLS]

Can we generalize for WW2 fighters how much flap extension was required to create washout for the wingtips? I'm assuming it was typical for full flaps and I'm curious if that's true and if it was true for the halfway setting.

[Stoney]

Can we generalize for WW2 fighters how much flap extension was required to create washout for the wingtips? I'm assuming it was typical for full flaps and I'm curious if that's true and if it was true for the halfway setting.

Flaps don't create washout.  Washout is changing the angle of incidence of the wing away from what it is at the root.  Its sometimes referred to as "twist" since the changed angle of incidence gives the appearance that the wing is "twisted" from root to tip.  Flaps add wing area and camber, but only to the flapped area of the wing (i.e. that portion of the wing that has flaps along the trailing edge).  The effect of flaps is to create a higher Clmax, lower stall speed, and create a "nose-down" approach angle, giving  the pilot a better view over the nose (sometimes).  Flap use also decreases the stall angle of attack, for the flapped area of the wing only.  Now, you could consider this effect as creating twist of a sort, since it will encourage the flapped area of the wing to stall before the wingtips (potentially), but this is not the purpose they are designed for.

[FLS]

Yes I realize that flaps don't actually twist the wings when they deploy. Flaps can cause the inner portion of the wing to stall sooner than the outer portion. When flaps have more than one position I assume this is unlikely to occur at the first flap position and likely to occur at the fully open flap position. My question was what point of flap extension would typically cause the flapped portion of the wing to stall first?

[PJ_Godzilla]

Flaps don't create washout.  Washout is changing the angle of incidence of the wing away from what it is at the root.  Its sometimes referred to as "twist" since the changed angle of incidence gives the appearance that the wing is "twisted" from root to tip. 

I'd qualify: that's one type of washout; geometric. You can also do it with a section change (aka aerodynamic washout). All the more reason that tip to root section change in the 190 baffles me.

[moot]

A blind guess - have you guys looked at the Ta 152 C and H wing designs?  May be some clues there, as everywhere I've read it's considered to be "what the 190 was supposed to be".

[Charge]

I think that 152C has a similar wing in every other aspect but it was only bigger to counter the increased weight, I'd say that wingloading remained almost the same as in 190A8. Obviously Tank thought that for low alt work such wing was adequate.

Dunno 'bout that H wing.

"According to the following reference "Elastic deformation of the Fw 190 outer wing occurs and shifts the load distribution outward" (This would even more of the wing to reach its stalling lift co-efficient simultaneously).
Ref Gross, P -"Die Entwielung der Tragwerkkonstruktion Fw 190", Bericht 176 der Lilllenthal-Gesellschaft, 2 Teil, January, 1944"

In reference to Lednicer article U guys don't think that in comparison between 190, Spit and P51 the larger wings flexed less? 

-C+

[PJ_Godzilla]

I think that 152C has a similar wing in every other aspect but it was only bigger to counter the increased weight, I'd say that wingloading remained almost the same as in 190A8. Obviously Tank thought that for low alt work such wing was adequate.

Dunno 'bout that H wing.

"According to the following reference "Elastic deformation of the Fw 190 outer wing occurs and shifts the load distribution outward" (This would even more of the wing to reach its stalling lift co-efficient simultaneously).
Ref Gross, P -"Die Entwielung der Tragwerkkonstruktion Fw 190", Bericht 176 der Lilllenthal-Gesellschaft, 2 Teil, January, 1944"

In reference to Lednicer article U guys don't think that in comparison between 190, Spit and P51 the larger wings flexed less? 

-C+

Charge, a couple of things I can add:
1. I know the 152 utilized the same aero sections root and tip (23015.3, 23009) but am unsure of the taper profile or twist profile, if any. Obviously the aspect ratio was much higher and I'm pretty certain the wingloading was lower than the Dora but I only say that because the sustained turn rat eis better (which clearly follows, assuming the powerloading enables similar bank angles and the CLMax is similar, possibly a bad assumption).
2. I would expect lower-loaded wings to flex less, but it doesn't necessarily follow because the section depth of the wing is also variable (recall MY/EI where y will go like section depth and I will go like section depth cubed). This is especially critical in the case of the Spitty because I think i'ts got a flimsy and shallow section, judging by the way it loses wings. I'd like to see sction data on that one. As for the -51, the loading is high but, again, I lack section info.

Further, I'd expect the flex to be distributed parabolically root-to-tip so you'd really need to do the thing as a spanwise integral.

[Stoney]

In reference to Lednicer article U guys don't think that in comparison between 190, Spit and P51 the larger wings flexed less? 

-C+

Agreed...I don't know why he listed that in the article. 

[Stoney]

A blind guess - have you guys looked at the Ta 152 C and H wing designs?  May be some clues there, as everywhere I've read it's considered to be "what the 190 was supposed to be".

I personally don't think there's anything wrong with the original wing.  You fly the plane inside its envelope, and it works.  You fly outside, and it doesn't.  That's every plane that's ever been built.

[moot]

Me neither, just thought that that qualitative description could be the clue some of you guys seemed to be looking for.

The H's wing is made for very high altitude rather than general purpose, but I'm pretty sure it has the outer ends twisted so they stall last, pretty differently from the C model's wing.

[drgondog]

"According to the following reference "Elastic deformation of the Fw 190 outer wing occurs and shifts the load distribution outward" (This would even more of the wing to reach its stalling lift co-efficient simultaneously).
Ref Gross, P -"Die Entwielung der Tragwerkkonstruktion Fw 190", Bericht 176 der Lilllenthal-Gesellschaft, 2 Teil, January, 1944"

In reference to Lednicer article U guys don't think that in comparison between 190, Spit and P51 the larger wings flexed less? 

-C+

'Flexing' is all about stiffness (deflections) for loads applied in both bending and torsion.   Impossible to analyze by 'inspection'. Comparisons would first examine the aero load distribution and the spar/torque box design but even the t/c ratio is deceiving for a deep chord design like the Spit as the actual depth of the main spar, spanwise was probably close to the other designs. 

I suspect Lednicer included the article because he was intrigued by cause and effect of manuever on the 'vicious departure' charcteristicsof the 190 near stall vs the zero twist on the 20% of the semi span... and trying to figure out why Tank would design a wing which virtually stalls all at once for 80% - when stall, by and of itself does not follow easily (or symmetrically) predictable rules in asymmetric flight

 

[Ardy123]

'Flexing' is all about stiffness (deflections) for loads applied in both bending and torsion.   Impossible to analyze by 'inspection'. Comparisons would first examine the aero load distribution and the spar/torque box design but even the t/c ratio is deceiving for a deep chord design like the Spit as the actual depth of the main spar, spanwise was probably close to the other designs.  

I suspect Lednicer included the article because he was intrigued by cause and effect of manuever on the 'vicious departure' charcteristicsof the 190 near stall vs the zero twist on the 20% of the semi span... and trying to figure out why Tank would design a wing which virtually stalls all at once for 80% - when stall, by and of itself does not follow easily (or symmetrically) predictable rules in asymmetric flight

Drgondog,
How much did areo engineers know back then. I mean, were they able to mathematically predict the general behavior (such as stall handling), or was it more along the lines that they guessed (based on simple mathematical models), then they built it and tested to see if they got the result they wanted?

[Stoney]

'Flexing' is all about stiffness (deflections) for loads applied in both bending and torsion.   Impossible to analyze by 'inspection'. Comparisons would first examine the aero load distribution and the spar/torque box design but even the t/c ratio is deceiving for a deep chord design like the Spit as the actual depth of the main spar, spanwise was probably close to the other designs. 

I suspect Lednicer included the article because he was intrigued by cause and effect of manuever on the 'vicious departure' charcteristicsof the 190 near stall vs the zero twist on the 20% of the semi span... and trying to figure out why Tank would design a wing which virtually stalls all at once for 80% - when stall, by and of itself does not follow easily (or symmetrically) predictable rules in asymmetric flight

 

I kind of tend to think that the article existed for the 190, but there was no known analysis for the other two.  So he included it.  However, based on the analysis of the other two aircraft, it was inconsistent for him to throw that little wrench in the mix.  Generally speaking, since most WWII aircraft were in the 5-6 aspect ratio range, I'd guess wing flex from bending was fairly inconsequential.  Torsion flex should be low since most used double spars as well, but I'm just spit-balling on both.

[Plazus]

Fowler flaps for the win!