fw 190a5 flight model

[Gaston]

Originally Posted by Herra Tohtori

I have yet to understand why wing bending would significantly affect the turn capabilities of these aircraft. It's like saying you can't measure a flag pole's height by putting it flat on the ground, because then you're measuring its length instead...

Logical parse-errors aside, what I can glean from the thread is as follows:

Apparently, Gaston's claim is that since no wing bending tests have been done to measure dynamic wing loading on these aircraft, we can't make accurate predictions about their turn performance.

However, the fact of the matter is this:

-Wing bending can not decrease the aircraft's mass.
-Wing bending can not increase the maximum lift produced by the wing.

Latter point can be proven by

a) assuming that the wings do not deform significantly when aircraft is flown within the flight envelope (and over-g tends to permanently deform the airframe, often fatally)

and

b) in a dihedral setup of wings, when the wings bend upwards under load, the lift can only decrease as the total wing span decreases.


Since the aircraft's weight is not affected by any wing deformations (how could it?) and the wing deformations cannot significantly alter the lift capabilities of the wing to positive direction, it naturally follows that wing bending does not have significant effect on the aircraft's lift to weight ratio at different angles of attack.

A simple fact of rotational physics is that for an object to stay on a circular path, a centripetal force (lift) is required to accelerate (g-forces) the object's mass towards the centre of the circular path.

The equation for this force is simply F = ma and no nonsense about wing bending will change the fact that you need certain amount of LIFT to turn an aircraft of certain MASS at a certain rate and turn radius.

You can increase turn rate and decrease turn radius by either increasing lift, or decreasing mass. I think we can all agree that the weights of WW2 aircraft are fairly well documented, so this entire argument can be condensed to the following statement:

Gaston's claim is that the FW-190 Anton models produced significantly more lift than aerodynamical models and testing suggest, especially on low speeds (which, incidentally, is where any wing provides the least lift, if you know anything about aerodynamics).

What this magic mechanism would be, he neglects to comment on. The problem, here, is that aerodynamics is a very well documented science and going against it would require a bit more than cherry-picked pilot reports interpreted with a hefty bit of bias.

Your comments show little understanding of what I said.

I said the wings on these old aircrafts ALWAYS bend more than previously assumed for a given horizontal turn, since wind tunnels do not imitate a curved trajectory, and wing bending on these old nose-pulled types was never actually measured in turning flight (dive pull-outs measurements would not count because of the prop unloading in the dive)...

The structural limit before permanent deformation on these fighters was typically a factor of two, so way beyond the assumed loads: 14 Gs on the Me-109G and 13 Gs on the P-51, so there is plenty of room for the structure to bend more than the assumed 6 or 7 Gs of assumed actual wing bending load.

If you don't understand that more wing-bending applied differently among types can play havoc with wingloading assumptions, and is important for the wingload hierarchy between aircrafts, I don't know what to say to that... Your comment makes absolutely no sense.

Even Glider would readily agree that if the wingload is added to unevenly across types, it would change the wingload hierarchy between types, which is what this is all about...

Your comment that weight cannot be added to just because an object is in flight seems on its face nonsensical: If I press down, say through leverage, with a fifty pound force on an 80 lbs block, flying or not, it will then become (for all practical purposes) 30 lbs "heavier" than the "heavier" 100 pound block, flying or not... I cannot fanthom what you fail to get in this...

I never said the FW-190A produces more lift at lower speeds and lower Gs than at higher speeds and higher Gs: I said that the "extra" load is proportionately greater at lower Gs, because it is not changed by speed but by power, and the power stays the same since it is assumed to be at the same maximum in all turns, high or low G, for simplicity's sake...

So it is logical that an aircraft that has less of that "extra" power load (because of better leverage over a shorter nose) will benefit more at low speeds where the power is "larger" compared to the "pure weight" G loads... But at high G loads the actual mass of the aircraft is multiplied by the Gs, while the power is assumed the same, so the lighter aircraft benefits more than the heavier aircraft from high Gs, and the "power leverage load" is proportionately smaller to the "real" G load, so having a big advantage in "leverage power load" (like the FW-190) is less significant and becomes less and less significant as the turn becomes more and more tight beyond what is sustainable in speed...

At high Gs, weight matters increasingly more than power, everyone should be able to understand that... Hence the FW-190A's turn performance goes down relative to lighter fighters when Gs go up beyond a sustainable speed... Which is exactly what can be observed in innumerable combats...

There is no way, if you accept the premise of an extra load on the wing due to power, that any of this is debatable...

As for the issue of where the extra lift comes from, it is a thorny issue, but since we don't know how much those wing actually bend in turning flight (thus with assymetrical air inflow), who can say the extra lift is not there?

If there is extra wing bending, and if it changes with power level, then it means that the extra lift is there, and it is power-related, regardless of what our other assumtions are...

Note that I attribute the load to the leverage of the power coming from a long nose, so that is why more recent studies of very advanced jet fighters completely failed to uncover this extra power load... The existence of such in-flight wing bending tests seems not to overlap further back than the early jet age... Current warbird operators do not use wing strain gauges in flight, at least not routinely...

I also think that one of the features of that extra "nose power" load is that the width of the prop surface creates its turn assymetry through increased thrust in the disc's inside turn half, which increased thrust could help "mask" the inevitable extra drag needed for that extra load on the wings...

By saying "wing bending cannot create extra lift", you are confusing cause and effect... The cause of the extra lift is obviously complex if it was hidden for 100 years (but it isn't so outlandish if you include the "gradually increasing" assymetrical inflow of air in a turn, which is not duplicable in wind tunnels)...

In any case I'll be back: I am now compiling a list of P-47D combat reports to answer Glider's challenge. To be fair to him, the ratio of multiple 360 turns to dive followed by zoom seems more like 70-30 than the 90-10 I previously said, and it has to be added more than half of all the reports are a fairly meaningless jumble of actions, but I think Glider will find it hard to match the number of meaningful turn battles with an equal amount of dive and zoom, especially if dives followed by a long chase are excluded...

This compiling is very rewarding for me, as the accounts do clearly demonstrate the superiority, in low-speed turns at any altitudes, of both the P-47D and the FW-190A to the Me-109G (and the slight superiority of the FW-190A to the P-47D).

Gaston