If you had an airforce...

[davparlr]

Davparlr,


Speed is the only advantage the P-51H has, and had it been introduced then it would've been facing Jumo 213EB powered Ta-152's which were just as fast.

You forgot to mention the P-51H's advantage in climb, dive, and acceleration. Now for the Jumo 213EB I did find a faint line on speed chart for Fw that had the EB. This is what I got, in order of fastest first (obviously, the P-51H data wasn't on the chart).

SL
P-51H 410 mph
Fw-190D-12 381
Ta-152H-EB 374
Ta-152H 370

5k
P-51H 430 mph
Fw-190D-12 399
Ta-152H-EB 393
Ta-152H 390

10k
P-51H 444 mph
Fw-190D-12 416
Ta-152H-EB 411
Ta-152H 397

15k
P-51H 440
Fw-190D-12 431
Ta-152H-EB 421
Ta-152H 416

20k
P-51H 465
Fw-190D-12 448
Ta-152H-EB 441
Ta-152H 436

25k
P-51H 470
Fw-190D-12 459
Ta-152H-EB 449
Ta-152H 449

So, it is apparent that the P-51H has a qualitative advantage in airspeed over all the latest Fw aircraft for the altitudes discussed.

As for as climb is concerned, it is reasonable that the Fw-190D-12 is equivalent to the Dora 9 up to about 18k and better above. Compared to the P-51H, it would be less to this altitude, but close in pretty fast up to 25k. Since the Ta-152H-EB airspeed is only about 5 mph faster than the Ta-152H, its climb would probably fall about 100-150 ft/min higher. This would not improve its performance very much relative to the P-51H.

As for power loading, the Ta-152H-EB would have to generate 2685 hp to equal the P-51H. And that hp would certainly provide more than 5 mph increase over the Ta-152H. Power increase is probably about 200 hp. The D-12 was probably close.

If ?? If ?? Now davparlr come on, there really should be no doubts.

Ofcourse the Ta-152H will turn better at all speeds as it's got both a much lower lift loading and a much higher L/D ratio.

Did you ever recalculate lift loading at the correct weight?

Ailerons don't control pitch. Like many pilots have said, flying the P-51 at high speed was like driving a truck, the elevator controls got stiff as concrete. The Fw-190 and Ta-152 however feature almost dangerously light controls at high speed, and care had to be taken regarding moving the stick around in high speed dives as you could quickly cross the structural integrity barrier.

Sorry about the aileron comment. I must have had a old age moment. I thought you addressed ailerons.

Okay, lets look at the elevators then. Your comment does not agree with the Fighter Conference on their evaluation.
Elevators
Force-5 good, 2 fair, 1 poor-1 high, 2 moderate, 16 light
Effectiveness-18 good, 10 fair

Diving characteristics
Acceleration-21 good
Stick force-5 good-1 moderate, 10 light

These test where designed to compare combat capabilities. It must be noted that all of the military pilots for the P-51 were Naval aviators. Had there been any problem with the elevators or the stick forces, you can bet they would have complained, as they did about lateral control and rudders of the plane.

In addition, I read many combat reports; many included high speed dives, with no mention of problems staying with the enemy, or problems pulling out. It might be interesting to note that one pair of pilots were jumped by a pair of "long nosed Fw-190s" and one was shot up but managed to "out turn" the Fws. They disengaged. Pilot reports are interesting, aren't they?

I don't see anything here that indicates that the P-51 was not superior below 25k ft. The D-12 comes close.

That brings up the question, why did Germany build the Ta-152H when the D-12/13 seems to be the better performer up to about 37k ft.? There wasn't any allied aircraft that I know that was flying above that altitude. They certainly didn't need a long range escort.

 

[Soren]

According to the chart the top SL speed with the EB engine is 605 km/h, and climb rate would increase by approx. 250 to 300 ft/min at SL but considerably more so with increase in altitude.

And regarding your question about using the right weights, yes I used the right weights, I tried with both 4,300 kg 3,900 kg, no change the P-51H still has a far higher lift-loading and much worse L/D ratio, and finally its airfoil makes for poor flight characteristics in turns.

Finally regarding the elevator control forces of the P-51, I have qoutes from -51 pilots who don't agree with you at all Davparlr! They mention that 109's pulled out of high speed dives much quicker than they ever could.

 

[Soren]

Well chock another one up to wiki...

Well perhaps, I can't say. I've always known about the electric/hydraulic horizontal stabilizer control system of the D-9 series forward, so it seems logical that it was applied to aileron control as-well.

 

[drgondog]

Like many pilots have said, flying the P-51 at high speed was like driving a truck, the elevator controls got stiff as concrete. The Fw-190 and Ta-152 however feature almost dangerously light controls at high speed, and care had to be taken regarding moving the stick around in high speed dives as you could quickly cross the structural integrity barrier.

The elevator response was not stiff except for being deep in compressibility which would have been similar in Fw. You have a reference that says the Fw 190 had 'light' control forces for all axes in near compressibility?

Not likely. What I have read is only in high speed could a 51 match the Fw 190 roll rate - you seem to imply the opposite?

As for Yaw - The reverse boost rudder tab was intentionally designed to force more rudder control force in a high speed rolling manuever or yaw control input - again we are talking about effects > .50 Mach.

 

[Soren]

Bill,

Again we're talking about pitch, which is controlled by the elevators, not roll rate which is controlled by the ailerons. Also the NACA roll rate tests you're refering to don't show the Fw190's true roll rate, which was nearer 180 degrees pr. sec at max. The result is likely due to the improperly adjusted ailerons on that bird, that would be Gene's explanation anyhow.

On another note if KK is right about the aileron boost on the D-13 Ta-152 then these would be unrivalled in high speed maneuvers.

The elevator response was not stiff except for being deep in compressibility which would have been similar in Fw. You have a reference that says the Fw 190 had 'light' control forces for all axes in near compressibility?

Well according to Gene the control forces in pitch were very light even at the redline speed of 850 km/h, and almost to the point where it was dangerous as a rookie pilot could quickly overstress the airframe if he made a too eager pull out.

The electric/hydraulic horizontal stabilizer control obviously has something to do with this.

 

[davparlr]

According to the chart the top SL speed with the EB engine is 605 km/h,.

Looks to me like the dotted line is closer to 602, but, I'm old and my eyesight is, lets say, degraded.

and climb rate would increase by approx. 250 to 300 ft/min at SL but considerably more so with increase in altitude

Your rate of climb increase doesn't seem unreasonable to me. However, I would tend to disagree with your statement about the increase in altitude. The airspeed difference between the Ta-152H and the Ta-152H-EB does not appear great until about 9.5 km (31k ft), where it is about 15 km/hr (9 mph). This implies, to me, that hp difference is not great and therefore, neither will climb rate.

And regarding your question about using the right weights, yes I used the right weights, I tried with both 4,300 kg 3,900 kg, no change the P-51H still has a far higher lift-loading and much worse L/D ratio, and finally its airfoil makes for poor flight characteristics in turns.

I certainly would like to see how you figured this, but I won't argue the point.

Finally regarding the elevator control forces of the P-51, I have qoutes from -51 pilots who don't agree with you at all Davparlr! They mention that 109's pulled out of high speed dives much quicker than they ever could.

Agree with me? You have me confused with Pax River flight test pilots (Navy) and contractor flight test pilots. Of course, what do they know? By the way, there were 38 pilots rating the P-51 and not one commented about problem of heavy elevator operations and dive was one area of evaluation. And the Navy pilots were no fans of AF aircraft!

 

[Soren]

I certainly would like to see how you figured this, but I won't argue the point.

The lift-loading part or the L/D ratio part ? The Lift loading you should know by now so it must be the L/D ratio you're questioning.

Well davparlr, the higher the wing AR the more efficient the wing is. A higher AR wing features a lower Cdi and a higher Clmax than a lower AR wing, giving the higher AR wing a higher lift to drag ratio (L/D), which is crucial to energy retention in maneuvers.

The L/D ratio of an a/c is derived as such:

L/D ratio = Cl / Cd

Cd = Cd0 + Cdi

Cd0 = {Negligable as it always lies in the 0.02 -0.025 area}

Cdi = (Cl^2)/(pi*AR*e)

The L/D ratio of the wing alone is derived as such:

Cl / Cdi = L/D


So to demonstrate the importance of wing AR alone lets compare two similar a/c with different AR wings with the same airfoil.

For the comparison we will assume the higher AR wing has a Clmax 0.05 greater in magnitude, while both a/c have the same Cd0 of 0.02:

Aircraft Nr.1 (Wing AR = 9)
(1.35^2)/(pi*9*0.85) = 0.0758326494

Cd = 0.0758326494 + 0.02

1.35 / 0.0958326494 = 14.0870571
__________________
L/D = 14.08

Aircraft Nr.2 (Wing AR = 6)
(1.3^2)/(pi*6*0.85) = 0.105479158

Cd = 0.105479158 + 0.02

1.3 / 0.125479158 = 10.3602863
__________________
L/D = 10.36


L/D ratio differential = 35.9 %

Now let's compare the Ta-152H and P-51H:

Ta-152H

(1.62^2)/(pi*8.94*0.83) = 0.112580856

1.62 / 0.112580856 = 14.3896579
__________________
L/D ratio = 14.38

P-51H

(1.35^2)/(pi*5.8*0.82) = 0.121976402

1.35 / 0.121976402 = 11.0677146
__________________
L/D ratio = 11.06


Difference in L/D ratio = 30 %

 

[drgondog]

The lift-loading part or the L/D ratio part ? The Lift loading you should know by now so it must be the L/D ratio you're questioning.

Well davparlr, the higher the wing AR the more efficient the wing is. A higher AR wing features a lower Cdi and a higher Clmax than a lower AR wing, giving the higher AR wing a higher lift to drag ratio (L/D), which is crucial to energy retention in maneuvers.

The L/D ratio of an a/c is derived as such:

L/D ratio = Cl / Cd

Cd = Cd0 + Cdi

Cd0 = {Negligable as it always lies in the 0.02 -0.025 area}

Soren - at high speeds Cd0 dominates and Cdi which does depend on AR and CL becomes less important.

In fact the Cd0 of a 51H is the lowest of the prop fighters in the war and close (but higher) to the P-80

Cdi = (Cl^2)/(pi*AR*e)

The L/D ratio of the wing alone is derived as such:

Cl / Cdi = L/D


So to demonstrate the importance of wing AR alone lets compare two similar a/c with different AR wings with the same airfoil.

For the comparison we will assume the higher AR wing has a Clmax 0.05 greater in magnitude, while both a/c have the same Cd0 of 0.02

This is an incorrect assumption - that Cd0 is the same unless you can prove it. The only detailed source for referenced wind tunnel and flight test Cdo is in Lednicers Reports which we beat to death. In that report the 51D was significantly lower than the Fw190D-9 and a lot cleaner than the Spitfire IX.
:

Aircraft Nr.1 (Wing AR = 9)
(1.35^2)/(pi*9*0.85) = 0.0758326494

Cd = 0.0758326494 + 0.02

1.35 / 0.0958326494 = 14.0870571
__________________
L/D = 14.08

Aircraft Nr.2 (Wing AR = 6)
(1.3^2)/(pi*6*0.85) = 0.105479158

Cd = 0.105479158 + 0.02

1.3 / 0.125479158 = 10.3602863
__________________
L/D = 10.36


L/D ratio differential = 35.9 %

Now let's compare the Ta-152H and P-51H:

Before you start the comparison, explain why you wish to start at Max CL presumably at max AoA for both ships, further presuming either comparisons in max climb or max turn, but not at high speed?

And as you proceed below why you are using different airplane efficiency factors between the two ships. What is your source of data?

Ta-152H

(1.62^2)/(pi*8.94*0.83) = 0.112580856

1.62 / 0.112580856 = 14.3896579
__________________
L/D ratio = 14.38

P-51H

(1.35^2)/(pi*5.8*0.82) = 0.121976402

1.35 / 0.121976402 = 11.0677146
__________________
L/D ratio = 11.06


Difference in L/D ratio = 30 %

Having asked the questions I think the Ta 152 intutively will climb and turn better in a sustained combat.

Neither one of us have the slightest idea based on the limited factual data regarding prop efficiencies, actual Cd0, thrust as function of altitude/boost, Cd0, etc what the energy profile looks like.

 

[davparlr]

Having asked the questions I think the Ta 152 intutively will climb

Seems your intuitiveness is a bit off. The P-51H has a better rate of climb than the Ta-152H probably up to 25k. In time to climb, it is equal or better to 33k. This is at equivalent fuel weights.

and turn better in a sustained combat.

Like the F6F pilot fighting a Zero, it would be unwise for the P-51H to engage the Ta-152H in a turning fight at any altitude. But it didn't keep the F6F from dominating the Zero.

I haven't really looked at Soren's calculation. I will respond a bit more in a few weeks, when I get back from vacation.

 

[Soren]

This is an incorrect assumption - that Cd0 is the same unless you can prove it. The only detailed source for referenced wind tunnel and flight test Cdo is in Lednicers Reports which we beat to death. In that report the 51D was significantly lower than the Fw190D-9 and a lot cleaner than the Spitfire IX.
:

No Bill, it isn't incorrect cause if you note what I said then you will see that I was comparing two similar aircraft just with different AR wings and same airfoil, hence the similar Cd0.

Ofcourse the Ta152 P-51 won't have a similar Cd0 figure, they're two very different looking a/c.

Before you start the comparison, explain why you wish to start at Max CL presumably at max AoA for both ships, further presuming either comparisons in max climb or max turn, but not at high speed?

I am comparing the a/c at Clmax because that is where they are going to be closest to in a turn fight. Remember this is about turn performance, not straight out speed. And so the 30% difference is only at the point where both a/c are pulling their hardest turn.

Furthermore Cd0 is not very important in turns, which is what we're debating here, hence why it is neglible as it always lies in the 0.02 - 0.025 region.

And as you proceed below why you are using different airplane efficiency factors between the two ships. What is your source of data?

You mean the Oswald Efficiency factor I would presume ? Well I've been looking at NACA reports and the NACA 23000 series airfoil has a general advantage in 'e' factor over the P-51's NAA airfoil at any given planform. And so to be fair I made the difference very small, 0.82 vs 0.83, which is fair considering that on average the NACA 23000 series airfoil beats the NAA airfoil by 0.05 atleast.

 

[drgondog]

Soren - we have dived down this rathole too many times to begin again.

One of the reasons i put the altitude modifications to Crumpp's performance mods on hold is two fold.

1. Reliabe Cd0 is nigh impossible to find from sources on internet for the ships of interest
2. Bhp vs Altitude for different ships at top speeds is difficult to get a.) in detail, and b. )corroborative between different flight tests with same engine and boost.

If 2. was available and reliable we could get the Thp and from that a decent approximation to the Cd0 of that airframe during the test runs and speeds.

For maneuvering fights at different altitudes both of these ships should have different advantages/disadvantages depending on the altitudes and hp characteristics of the way their engines are geared, the respective velocities and thrust state entering the turn, the rate the energy bleeds off due to the respective drag profiles as the turn proceeds.

So back to the point.. the relative Cd0 between the ships IS important when entering the turn at high speeds,

The oswald/aircraft efficiency has a variety of factors but the most common one of imterest is tip chord ratio and then tip geometry as it influences tip vortices - winglet designs being the most important. You threw out values that were differnt. As near as I can tell there is no factual basis to asume that either they are the same Or different.

Ditto Cd0 for the reasons I cited. Unless you can point to well supported references, assuming Cd0 or 'efficiency' factors are suspect.

At the end of the day, even Clmax is suspect unless accompanied by flight test and wind tunnel - and remember both of those are effected by aeroelastic considerations of the stiffness of the wing to resist torquing in a high G turn.

ClMax for airfoil data is largely 2-D unless other wise noted which is, as you know why AR and e are important considerations moving from theoretical to real.

 

[Soren]

Bill,

The Clmax figures presented have all been established in windtunnel and flight tests, none are assumptions, they're the real thing, so there's really no point in discussing it.

As for diving down a rathole, well what the heck is that supposed to mean ?? This isn't about CdSwet or anything like that we were discussing a long time ago.

Also why is it you keep clinging to the Cd0 ? It has close to no effect at all in turns, and again we're comparing turn performance NOT straight out speed. It is for straight out speed where Cd0 becomes important.

And finally regarding the Oswald efficiency factor, well Bill wing designers from all sides took this into account and designed their wings to have the highest value possible, altering tip geometry, thickness, wash out etc etc to reach the optimum value.

I have an interesting chart from NACA which discusses and illustrates the difference in 'e' between different geometry wings of different thickness and AR. According to that report the Ta-152's wing design would've had a 'e' figure around 0.83 while the P-51's wing designw ould have one around 0.82 (Taking the NAA airfoil into consideration), with the 23000 series airfoil in increases to around 0.86 to 0.87. The NACA 23000 airfoil creates elliptical lift distribution which is what increases the 'e' factor.

 

[fly boy]

Why didn't you just edit it then?

oh yea i kinda forgot

 

[drgondog]

Bill,

The Clmax figures presented have all been established in windtunnel and flight tests, none are assumptions, they're the real thing, so there's really no point in discussing it.

Soren - I just agreed ClMax as you presented it is fine for level flight, and also for climb - but mention high turns infuence aeroelastic bending and torsion. You have wind tunnel results for this?

As for diving down a rathole, well what the heck is that supposed to mean ?? This isn't about CdSwet or anything like that we were discussing a long time ago.

Soren - I am not attacking you. I am not challenging the equations, other than the equations hold in a free body diagram but comparing the two against each other need specificity of Thrust, and the velocity you are making the comparison for

Maybe I missed that part of your analysis?

I pointed out that a series of assumptions you made about Cd0 and e may not be true absent sources everyone can look at and make their assumptions about your assumptions. So as you have differences on e and assumptions on Cd0 - what is your reference that we can all look at?

What did I miss on your presented sources to validate the numbers to insert for Induced Drag and Parasite Drag

Also why is it you keep clinging to the Cd0 ? It has close to no effect at all in turns, and again we're comparing turn performance NOT straight out speed. It is for straight out speed where Cd0 becomes important.

CD0 and Parasite drag are interchangable unless you define what else you are addingg to wetted drag to build up to total Parasite Drag of that airframe at that velocity and altitude? The CDwet in Lenicer's report of .0053 very closely agreed with the published Ames and NACA and NAA Cdwet data from wind tunnel data and calculations at the Reynold's number of the tests.

IIRC the flight speeds of the finite element model was (~ 320 mph @15,000 feet??) but Ill have to go back and check. Whatever, what is the Cdwet for the Ta152 and what other values do you have to support your assumption for total Parasite Drag in your calculations?

So what data caused you to discuss the range of .020-.025, then arbitrarily pick the value you used?

And finally regarding the Oswald efficiency factor, well Bill wing designers from all sides took this into account and designed their wings to have the highest value possible, altering tip geometry, thickness, wash out etc etc to reach the optimum value.

So? You want to compare the oswald efficiency of the V-1 to the Me 109 and state they are the same? All geometry, wash out, tip geometry, AR, flap, LE, decisions were trade off's based on the desired best performance envelope. If the P-51 had been designed as a High altitude bomber interceptor it would have had different compromises. If the Ta 152 had been designed as a turn dogfighter to specifically defeat a Zero at low altitude and speed - ditto.

Further structural design is based on a variety of factors including carrier qual, manufacturing cost, material weights, stiffness requirements, climb performance targets, range, etc.

Fecal matter happens if compromise on the oswald/wing efficiency factor are made to accomodate other design requirements. Ergo they may not be optimal, nor the same

I have an interesting chart from NACA which discusses and illustrates the difference in 'e' between different geometry wings of different thickness and AR. According to that report the Ta-152's wing design would've had a 'e' figure around 0.83 while the P-51's wing designw ould have one around 0.82 (Taking the NAA airfoil into consideration), with the 23000 series airfoil in increases to around 0.86 to 0.87. The NACA 23000 airfoil creates elliptical lift distribution which is what increases the 'e' factor.

??? No airfoil per se creates elliptical lift distribution, but the planform and twist of the airfoil chord wise design do influence closely, or as close as feasible, an elliptical lift distribution.

Basically All airfoils designed into an elliptical planform will give you elliptical lift distributions. Ditto all airfoils designed into trapezoidal, semi elliptical, rextangular, etc can be made to approach elliptical via twist and AR design.

A mathmatically sound elliptical lift distribution is obtained with an elliptical wing planform, and can be achieved with zero twist.. but it can still stall at the tip rather than root - hence twist.

Good news on the chart. Introducing that earlier gives you total credibility on at least one source and provides any assumptions made for your debate opponent to agree/disagree the context of your presentation?

 

[namvet68]

For Fighter - Fiat G.55
Ground Support fighter - P-47
Attack Bomber - Mosquito
Med. Bomber- B-26
Heavy Bomber - B29
Recon - P-38

This is my selection and I think people always forget about the old B-26. The P-38 was used alot during WWII for recon missions.8)

 

[Soren]

Bill,

The NACA windtunnel tests were with entire wings, not just airfoils, and the established average Clmax was 1.58 for a wing with a TR of 15 to 09% and a AR of 6. And funny enough this is the exact same figure established by FW in their windtunnel and flight tests with the Fw-190.

As for aeroelasticity, well again the Ta-152's wing featured washout to combat this, just as the Fw-190 P-51, the Fw190 just had the added advantage of achieving full elliptical lift distribution in tight turns.

 

[drgondog]

Bill,

The NACA windtunnel tests were with entire wings, not just airfoils, and the established average Clmax was 1.58 for a wing with a TR of 15 to 09% and a AR of 6. And funny enough this is the exact same figure established by FW in their windtunnel and flight tests with the Fw-190.

What you said was "The NACA 23000 airfoil creates elliptical lift distribution which is what increases the 'e' factor."

The airplane efficiency factor "e' has three primary components, namelythe increase in drag due to non-elliptical spanwise airload distribution,the increase in trim drag and the increase ins in drag attributed to angle of attack.

Cdi= {CL>>2*[1+phi]/Pi*AR} + {CL>>2/pi*AR*e - CL>>2*[1+phi]/pi*AR}

The first {} is induced drag due to wing only, the second {} is due to all factors except wing, such as trim drag on elevator, or centerbody drag at high AoA.. looking at the above equation, it can be seen that the second {} values depend on magnitude of 1/e and (1+phi).

"e" varies from flight test vales primarily and from that it is the slope of CD vs CL>>2 usually between .75 and .95. For Preliminary Design purposes usually .8 is selected to start with.

"phi" is a correction factor dependent on taper ratio, and =0 for elliptical spanwise distribution. Empirical results for AR between .3 and .6, the increase to Cdi over an elliptical plan form is in the vicinity of 1%.

Phi is lowest for taper ratios of between .4 an .5 increasing for lower and higher values. Wings with TR = 4 have about the same results as a wing of elliptic planform

Phi is lowest for low aspect ratios (~.02 for AR=2 and increases to ~.075 for AR= 10)

The source, if you want to look at it is chapter 4.2 and 7.15 of Supersonic and Subsonic Airplane Design by Gerald Corning, Martin Aircraft Company and professor University Maryland - 1960 - or offer your own approach.

Bottom line - planforms influence elliptical lift distributions, twist influence approximations to elliptical wings re: elliptical lift distribution but the airfoil does not per se - it is planform of the wing

As for aeroelasticity, well again the Ta-152's wing featured washout to combat this, just as the Fw-190 P-51, the Fw190 just had the added advantage of achieving full elliptical lift distribution in tight turns.

Soren, washout has one primary function - namely reduce tip stall. Adverse Aeroelastic effects to the Fw 190 wing were caused by the torsion created by the ailerons under aerodynamic load. In the lower wing in a turn the Fw 190 wing reduced local AoA at the tip causing a tip stall.

This was an aeroelastic not aerodynamic cause. The wing was not quite stiff enough in the last 20% of the wing to resist the torque about the spar axis caused by the aileron load. Further the twist did not continue and the rotation caused by the torque caused the out board AoA to increase - and local CL increased past stall and boundary layer separation started prematurely - losing local lift at tip while the inboard half was doing fine.

More washout at the tip might have prevented this. I have no idea what the twist distribution was for the Ta 152 but the 51 was essentially steady whereas the Fw 190 was steady to about .85 span then no more twist for rest of wing.

Before diving into the great "aeroelastic' debate once more go back to the thread I posted on Aeroelasticity.

If you'll go back to your definition of 'Full Eliptical Lift Distribution' would you a.) define it mathmatically and b.) explain how the Fw 190 wing achieved it absent an elliptical wing, and c.) explain why you think the Fw 190 achieved such 'full elliptical Lift distribution" in tight turns where other aircraft did not?

All conventional plan form wings had design trade offs to reduce induced drag.

The one plan form that didn't need to compromise for minimum induced drag was the elliptical planform wing (spit close, Jug close but not as close, V1 sucked). So twist, AR and Taper Ratio and tip designs were ways a designer could closer approximate an elliptical lift distribution - but never reach it. So how do you think the Fw 190 and Ta 152 "broke the code'

 

[Soren]

Bill,

The Fw-190's wing was just as stiff as the P-51's if not more, it was the difference in twist which caused the different stalling behavior, it had nothing to due with insufficient wing tip strenght and I have no idea where you got that from.

And as for the Fw-190 achieving elliptical lift distribution in turns, it did, go ask Gene, I questioned him very directly about this:

Soren said:
I see, so I was wrong when I said that Fw-190's wing achieved basically fully elliptical lift distribution in turns ?

Gene said:
No you are right. That is what causes the harsh stall.

And then regarding the 'e' factor, I dunno why you talk about "breaking the code" ? The designers went for optimal effeciency during specific conditions of flight, and in the case of the Ta-152 Fw-190 this was in tight turns. There was no optimum for all conditions, it was about compromising for a specific flight condition.

 

[drgondog]

Bill,

The Fw-190's wing was just as stiff as the P-51's if not more, it was the difference in twist which caused the different stalling behavior, it had nothing to due with insufficient wing tip strenght and I have no idea where you got that from.

I did not say anything about strength - Don't confuse strength with aeroelacticity or the susequent issues surrounding deflection, resonance or fatigue.

I explained that the combination of torsional deflection about the spar axis - and the combination of zero twist in the outboard 20% of the wing - IMO was the factor that caused the vicious stall. I 'got that' from my own knowledge of the forces on a sufficiently 'elastic' or 'torsionally suceptible to rotation about a spar axis' that a.) cause control reversals in a Spit wing and b.) the discussion of the apparent problem of high G stall of the FW 190 in Lednicer's report, as well as citing the FockeWoulf/LW report on the subject.
And as for the Fw-190 achieving elliptical lift distribution in turns, it did, go ask Gene, I questioned him very directly about this:

Go ask him again - this time specifically cite what I said about "elliptical vs 'elliptical like' and the design approaches used to take a non-elliptic wing and work toward achieving 'elliptical like' lift distributions.

Report back.

And then regarding the 'e' factor, I dunno why you talk about "breaking the code" ? The designers went for optimal effeciency during specific conditions of flight, and in the case of the Ta-152 Fw-190 this was in tight turns. There was no optimum for all conditions, it was about compromising for a specific flight condition.

Sigh - you missed the point.

OK - Prove from sources that a.) the Ta 152 and Fw 190 twist, e, AR, airfoil thickness, planform, etc were designed for optimal efficiency in 'tight turns'

Prove that the Ta 152 "e' factor was .83 and the 51H was .82

Prove that the Cd0 always falls between .20 and .25.

Prove that what ever value you chose above for Cd0 is valid.

Build empirically and mathmatically that CD0 for Cd wet and Cd -other, in fact fall between .20 and .25 for the P-51H.

If you can't then just say so. If you can - do so.

End of debate

 

[Vraciu]

I'll join this topic with my

VPFAF (Vraciu's Personal Air Force) VPAAF (Vraciu's Personal Army Air Force):

VPFAF (Vraciu's Personal Fleet Air Force)

Land-based fighters: N1K2-J Shiden-kai's
Land-based bombers: B-26F/G Marauders
Carrier-based fighters: F6F-5 Hellcats and F4U-1D Corsairs
Carrier-based torpedo bombers: B7A2 Ryusei's
Recon: C6N2 Saiun's, PBY Catalinas

VPAAF (Vraciu's Personal Army Air Force)

Fighters: P-47M/N Thunderbolts
Escort fighters: P-51D/H Mustangs
Mid bombers: B-26F/G Marauders, B-25J Mitchells
Heavy bombers: B-29A Superfortresses (with A bombs), Kawasaki Ki-91's
Recon: Spitfire PR XI's

Transport in both Air Forces: C-47/L2D3