fw 190a5 flight model

[MaxGunz]

Originally Posted by Gaston

Your comments show little understanding of what I said.

That's because your made-up nonsense cannot be understood in any logical sense.

I said the wings on these old aircrafts ALWAYS bend more than previously assumed for a given horizontal turn,

SOURCE?

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)...

SOURCE?

And when did they put full size planes in WWII wind tunnels?

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.

Ass-uming the pilot can take any 13 or 14 G's beyond momentarily, less than a second.

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.

SOURCE?

Something besides in the mind of Gaston, please!

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...

A new of line of unsupported BS?

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...

Because it is complete physics-violating BS to say that you can from within the plane press down and make the plane heavier. You are now in the realm of violating the 2nd Law of Motion in Grand Crank Style. The classic non-demo is a 150 lb man pulling his bootstraps with 160 lbs force and expecting to lift himself off the ground.
Pressing down on a block that you are not standing on does not apply to pressing down on a plane by any means within the plane. That does not include changing the controls that affect air flow (external to the plane) which does not change the weight of the plane regardless.

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...

Which is BS. Power/thrust does not change wingloading.

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...

So given that physics is wrong and your joke ideas are right, you have a muddled 'point'.

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?

Not you, that's for sure. How far the wings could cantilever without deforming was tested and known. They did test structures to destruction but then engineers did and still do things like that.

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...

If... Enough ... nothing real, no source... Then It Means, whatever you decide in your fantasyland ... Other Assumptions and non-factors from non-facts....

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...

What recent studies This Time? SOURCE?

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...

And now you're back to the old "Stress Risers" without actually using the words This Time Around. But it's the same unsupported stuff as before.

What is your SOURCE? Do you hold a model plane and imagine this while making zoomy sounds?

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)...

Obviously. They could predict what happened quite well without knowing the secret Gaston Force that does absolutely NOTHING. Since it had NO EFFECT they never knew it wasn't there! Oh, those Idiots!

If your ideas were right then perpetual motion would be possible.

[Herra Tohtori]

I will create a free-body diagram of the (relevant) forces affecting a flying aircraft in a turn when I have time for it.

I'll just note a few key factors here.

1. Maximum power of the engine is irrelevant at slow speeds.

If you were familiar with definitions of work and power you would understand this; I can show you why this is so but I don't know if you would understand the mathematics (it's reasonably simple but it does involve some grasp of differential calculus). For now, suffice to say that when an aircraft travels slower, the engines do less work per unit of time, which means by definition that their power output is reduced. Aircraft engines reach their peak power output only at maximum speed of the aircraft (same actually applies to automobiles!).

2. There is a component of thrust that is directed toward the centre of the turning circle.

This can easily be defined as

Fc = F * sin α

where F is the thrust of the propeller disk, and α is the angle of attack. Let's assume that α cannot be larger than critical angle of attack; α ≈ 15°

At critical angle of attack (maximum turn performance at any speed), the thrust toward the centre of the circle would be

Fc = F * sin 15° = 0.25 F

Hence, we can say that at most, only about quarter of the total thrust of the engine is directed inward and thus assisting in the turning radius. This, however, applies to all aircraft, not just FW-190 so it doesn't really help your point... especially as we get to point three.

3. Since we now know the assisting centripetal component of the thrust force, we can determine the assisting centripetal acceleration:

a = Fc / m = 0.25 F / m

since F/m is the thrust to mass ratio of any aircraft, we can DIRECTLY say that the thrust to mass (more commonly incorrectly expressed as thrust to weight ratio) does affect the turning performance.

Moreover, this simple exercise of physics shows us that aircraft turn harder when their engine produces more thrust.


Confusingly (or rather, not) we know that Spitfires have better acceleration and climb rate than FW-190, which means Spitfires have better thrust to mass ratio.

Which means that the expectation of the theory is that Spitfire engine can assist in turns more effectively than that of FW-190... which doesn't really help your case.


4. Quantitative analysis

How, then, does this centripetal acceleration produced by the engine thrust compare to the centripetal acceleration produced by the lift of the wings?

Well, again, simple exercise. If we assume that at certain speed v, the aircraft would be able to do a 3g turn, that means the wings produce enough force to produce 3 g's worth of acceleration (they can easily produce much, much more force up to the limit of their plasticity, in which they deform permanently, but since the discussion is about low speed performance let's keep it at that flight regime).

By contrast if we look at the maximum acceleration that the engine thrust can produce, we can immediately see that the thrust is about an order of magnitude smaller force than the lift of the wings. It's difficult to actually determine the thrust of these aircraft; however we can get some results by looking at how well they climb vertically. None of the WW2 aircraft can maintain their velocity (or increase it) in vertical climb; this means that the propellers produce less force than the aircraft's weight - their thrust/weight ratio is smaller than one.

At thrust/weight ratio of one, the engine could give the aircraft exactly 1g of acceleration. Since these aircraft get nowhere near that, let's be generous and assume the acceleration at standing start could be.. let's say 0.5 g's (it is probably less than this, but oh well...).

Now we can determine the centripetal acceleration by thrust:

ac = 0.25 a = 0.25 * 0.5 g = 0.125 g


What does this mean? Well, if a gliding aircraft at speed v can pull a 3g turn, with full power it could pull about 3.125 g turn (increasing it's turn rate and decreasing turn radius).

This applies to all powered aircraft, and the defining factor is the aircraft's thrust to mass ratio - or, unloaded acceleration by engine thrust alone.

Multiplying this by the sine of angle of attack you can directly get the assisting centripetal acceleration.

a(engine) = 0.125 g

a(lift) = 3 g

we can see that the assisting engine thrust is, at best, about 4% of the lift.

At high g-load the ratio further decreases because you can't pull critical angle of attack at high speeds - which means that most of the thrust is directed forward.


Now, if you're looking at two different planes with different thrust/mass ratios - yes, the plane with better thrust/mass ratio will provide more assisting centripetal acceleration.

However now you need to consider that the thrust/mass ratio of these aircraft had relatively small variations. What you will find is that the overwhelmingly deciding factor in turn rate is the lift/mass ratio rather than engine thrust. You might find small differences in the assisting thrust - let's say that one aircraft's engine might assist at 4% of lift, while another aircraft's engine might assist turning at 5% of the lift... but this would already mean a quite hefty 25% thrust/mass ratio difference!


Here we have shown that the engine thrust is primarily responsible for maintaining the cornering velocity (overcoming drag), and wings are primarily responsible for actually turning the aircraft.

I don't expect Gaston to really comprehend any of this, this is more for the benefit of others.

I'll make that free body diagram as soon as I can... now I must get going to school.

Toodles!

[K_Freddie]

Originally Posted by MaxGunz

Ass-uming the pilot can take any 13 or 14 G's beyond momentarily, less than a second.

I was at a Korea vets meeting, where the old guys were talking about pulling 12Gs in P51s and not blacking out ??? Maybe we're a lot tougher down south - Something to think about
Or maybe our blood pressure goes up radically when we have to deal with crap

[Gaston]

Originally Posted by MaxGunz

Because it is complete physics-violating BS to say that you can from within the plane press down and make the plane heavier. You are now in the realm of violating the 2nd Law of Motion in Grand Crank Style. The classic non-demo is a 150 lb man pulling his bootstraps with 160 lbs force and expecting to lift himself off the ground.
Pressing down on a block that you are not standing on does not apply to pressing down on a plane by any means within the plane. That does not include changing the controls that affect air flow (external to the plane) which does not change the weight of the plane regardless.


.

You don't seem to show much understanding either: Since the engine is obviously grabbing a huge volume of air (hundreds of tons of curving high-speed air, while itself with a contrarian "inner" passive desire to go straight, I might add), where does your restriction stand that the applied force must come entirely from within the aircraft?

I dare say my analogy of pressing down on a flying block with a lever while standing was more apt...

In your view, the aircraft can operate without an environment... This is what spaceships do... They have space around them: That's why they are called spaceships: And the maneuvers they do do indeed come entirely from within...

But this is not how aircrafts work...

Gaston

[Gaston]

Originally Posted by MaxGunz

Ass-uming the pilot can take any 13 or 14 G's beyond momentarily, less than a second.


.

First of all it is not 13 or 14 Gs, but 6-7 Gs plus 3 "Gs" worth of bending: So 9-10 Gs of structural load at most.

(It would explain some unexpected breakage and, interestingly enough, the failure of the P-51s guns to work properly despite likely ground wing-bending testing...

They never tested those guns in actual turning flight, and, as a result, the P-51's gun jams under G load were always triple that of the P-47: Going from 500 mrbf in early '44, to around 1000 in 1945, while the P-47 went from 1500 in early '44 to 3000 + in 1945... The improvements might have been in part due to lower late-war altitudes for both types)

In any case, those Gs are for the airframe's wing bending value, not Gs that the pilot actually feels, or are you just pretending?

Gaston

[MaxGunz]

Originally Posted by Gaston

First of all it is not 13 or 14 Gs, but 6-7 Gs plus 3 "Gs" worth of bending: So 9-10 Gs of structural load at most.

Really? Or did you just pull that out of your ear? Because the people who did the actual testing got higher values without guessing at all. They tested the structures to the breaking point.

(It would explain some unexpected breakage and, interestingly enough, the failure of the P-51s guns to work properly despite likely ground wing-bending testing...

Interestingly enough the failure of different ammo feeds to have failed under turning G's was known and written into the very histories you claim to have encyclopedic knowledge of.

They never tested those guns in actual turning flight,

Never? Anywhere? Not like you can't remember or find but actually never?

and, as a result, the P-51's gun jams under G load were always triple that of the P-47: Going from 500 mrbf in early '44, to around 1000 in 1945, while the P-47 went from 1500 in early '44 to 3000 + in 1945... The improvements might have been in part due to lower late-war altitudes for both types)

That and actually changing the ammo feed on the P-51. They had to do a change in the gear doors too and a whole list of fixes.

In any case, those Gs are for the airframe's wing bending value, not Gs that the pilot actually feels, or are you just pretending?

Gaston

First of all, you should learn about human G testing and G's. It's not just the G's, it's how long you are *at* the G's.

* Go through disturbed air and your plane maybe shakes, that is momentary G force. At higher speed the shake is more. In fact there are actual reference maximum speeds for flying in such conditions because you can break the airplane especially if you also try and maneuver in such conditions, like trying a hard pullout while buffeting.

As for cantilever wings, they are made to flex a certain amount, it's part of the design. It beats breaking. But even short-term G's can overload the wings, they do not fail the same way that humans do.

Watch a pilot pull 11.2 G's in the Red Bull Air Races.

[K_Freddie]

The race is on.....

[Treetop64]

...as an outsider looking in to an interesting discussion, Gaston, you might wanna consider giving up. You're equivocally arguing over semantics, to no constructive end, just for the sake of salvaging and continuing an argument.

It's not working.

[Gaston]

It is not pointless, because now after a few years of looking for wing-bending data, I realize wing bending measurements were not done in turning flight for WWII fighters: I am told by those who know that the -apparently- rare times during which wing bending data is gathered in flight, it is done by dive pull-outs only...

Would the P-51 have had jamming guns at three times the normal rate, particularly in turning battles, if they had done these tests?

As for the challenge I was issued by Glider, the ratio of P-47s out-turning Me-109s vs the opposite is pretty telling: I am sure Glider will have great trouble matching even one tenth of the P-47/109 outcomes I presented above...

Or one third for the dive and zooms vs multiple consecutive 360s examples...

So much for a great theoretical advantage...


I also wanted to adress the claim of violation of physical laws:

Imagine a situation where you have in each hand a pulley system that multiplies your pulling force by 100.

Imagine each system is connected to opposite extremities of a steel bar: Leaning back you pull say 50 lbs in each hand: 5000 lbs of pulling force at the other end of each pulley system.

If you alternately vary the force in each hand, would the steel bar offer any resistance to your moving it back and forth? Does no perceptible resistance mean the steel bar is not being pulled apart by 10 000 lbs of force?

This is what is called a violation of physical laws here...

My claim is that two large forces cancel each other out: One force is the resistance of the propeller to a curving trajectory, which I figure is around 100 lbs for each degree of angle of attack -hardly an outlandish figure...

The other force is a deformation of the void above the wing, which is linked to the above: This force has to be proportionately much greater because of a very unfavourable leverage relationship to the nose, where the prop is.

So the deformation of the void above the wing is the equivalent of having a much larger "pulley force multiplier" within the wing, faced at the other end by a much longer "lever" in the nose, both cancelling each other out proportionately as the AoA increases.

And, like the steel bar, the wing will know those extra forces are there, but won't really show much if you don't measure bending...



Of course, on a nose-pulled aircraft, for the two "extra" forces to be balanced, the CL must move in front of the CG (in addition to becoming greater in force), or the pilot would feel an extra effort in the stick to lean back the prop, which he clearly doesn't...

The forward displacement of the CL might seem to involve a significant effort*: But the CL is made of air, wind tunnels do not replicate a curving trajectory, and they do not replicate an object being held in the air entirely by the speed of its propulsion from the nose...

Or you can cling to the notion that the Me-109G out-turns P-47s...

Gaston

*I think the faster "outside turn" air leaks from the bottom of the wing, from the trailing edge, maybe a long way forward into the upper wing area, in any case gradually increasing and deforming the void above the wing, as well moving the CL forward, as the AoA increases. That would explain the larger lift forces which the greater they "increase", the more they demonstrate the wastage incurred from the nose leverage: That waste from the nose leverage increases the less the CL moves forward, because the CL moving forward is the wing's own opposing lever, and the less lever it has the more the upper wing void will deepen.

Hence the deeper the void above the wing, the less the CL has moved forward of CG...

[Igo kyu]

There is no suction, there is only pressure.