Spitfire XIV vs Bf-109 K-4 vs La-7 vs Yak-3

[Hunter368]

Very subtle Marcel. LOL

[kool kitty89]

Soren I think you need to be specific on which part Bill was wrong about.


And Bill, Soren already admitted that he was wrong about the aeroelastic effects being an intentional design feature, though they did occur in the way he described.

And mentioned earlier was that the 23000 series airfoil itself (without washout) generated an elliptical lift distribution, without an elliptical (or elliptical-like) planform


And one final thing, though the stalling occurring in high G turns is a disadvantage, the elliptical lift (and thus low induced drag) would benefit turn performance.

[drgondog]

Originally Posted by Soren

I was aware of that from the very beginning Bill and a long time before that as-well.

Explain
1. Aeroelasticity - How would you model an airframe system to yield analytical results

2. How you believe that the designers of the Fw 190 understood aeroelasticity and used that knowledge in their designs

3. How the analytical results from any approach in airframe design used during WWII were close toactual results under loads.

[kool kitty89]

Bill Soren already admitted he was wrong about that being an intentional design feature.

Originally Posted by Soren

Oh btw, Gene notes that the full elliptical lift distribution occuring in turns wasn't a design feature from the start, which I said it was, so on that point I was wrong and I gladly admit it.

plus from the original email post:

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

No you are right. That is what causes the harsh stall. It is not a design feature however. It is just and explanation for the two different stall characteristics of the design.

Quote:
Originally Posted by Soren
It was my understanding that the Spitfire's wing didn't achieve fully elliptical lift distribution because of the washout applied to the wing all the way out to the tips.

You are right on this too. The Spitfire does not achieve the full efficiency benefits of elliptical wing construction due to the washout. At the same time though it is probably the most efficient of the three. If we examine the aircraft at a design optimum point, you will find little to no difference.


So the debate is now settled I hope.

On another note, the comments Spitfire seem to say that (while similar in comparing all in the optimum conditions) it's wing would be the most efficient over a wide range of operation.

Since the Mustang and FW190 are designed to most efficient at one design point and the Spitfire has an elliptical wing which is efficient at all points, Lednicer's observation is correct in that the Spitfire probably has the most optimal of the three. Probably is used because the aerodynamic twist in the Spitfire wings in order to prevent the wing from stalling all at once reduces this efficiency. That too would be designed for an optimal point of performance.

[drgondog]

Originally Posted by kool kitty89

Soren I think you need to be specific on which part Bill was wrong about.


And Bill, Soren already admitted that he was wrong about the aeroelastic effects being an intentional design feature, though they did occur in the way he described.

KK - you might go back to page 77 when I outlined the foundation of elliptical wing design, how trapezoidal designs could closely approximate elliptical load distribution through twist and tip chord, then finally how 'G' forces did not influence lift distribution Until aeroelastic deformation (torsion/twist- or bending).

See when Soren started 'seeing the light'

And mentioned earlier was that the 23000 series airfoil itself (without washout) generated an elliptical lift distribution, without an elliptical (or elliptical-like) planform

ALL basic wings can be made to demonstrate an 'elliptical like' lift distribution - An Elliptical planform wing for example, using that airfoil, would get an elliptical lift distribution along the entire span with no change in chord twist as you move span wise from root to tip.

A Trapezoidal wing (i.e P-51 or Fw 190) using that same airfoil has to have twist of the chord as you move spanwise from root to tip. It will not be as efficient relative to total induced drag of the SAME airfoil as the Elliptical wing plan form. However, as you get a tip chord to root chord ratio around .4 to .5 you are getting close.

The reason the Elliptical Wing planform of the Spit used twist was to ensure that the inboard region of the wing would start to reach CLmax before the tip area. (the twist is 'downward' reducing the local angle of attack as you move spanwise outboard) - more at the tip than the root.So, the twist reduced the efficiency of the Elliptical planform with respect to induced drag (slightly) but gained additional tip stall prevention

And one final thing, though the stalling occurring in high G turns is a disadvantage, the elliptical lift (and thus low induced drag) would benefit turn performance.

Having lower induced drag is all about more efficiency of the wing, not much to do with respect to turn performance but all things equal I would prefere lower induced drag -------> implying slightly better energy retention between the two aircraft (less 'pull' against the thrust).

The stalling characteristics between the Fw 190 were more severe than a Mustang in the same high G turning manuever. Both had 'square' wing tips, Both had twist up to 81.% but the Fw 190 stopped the twist at that point, preferring to reduce the induced drag slightly from a comparable wing which twisted all the way out... which would be fine for straight line flight efficiency.

The Mustang gave plenty of warning (until full fuse tank screwed up stability) as the stall progressed from inboard to tip.

It (Fw 190) probably would have not had the severe snap stall in high G turn if the wing was perfectly rigid and that for a 'rigid - non torsioning' tip area, would have stalled more conventionally.. namely stalling from inboard out all the way, with tip area reaching stall after some decent buffeting of the tail due to the first losses in the root area?

Does that make sense?

[bada]

what a funny discussion!

so, let's talk numbers: i got the stats for the spit14 and i think kurfust has the stats for the k-4 somewhere, so let's compare how much planes were build , how much declassed and how much didn't saw action and will see what the better plane is!



Just a little explaination:
operationnal means assigned to squadron, what does NOT mean combat-operationnal! The plane was simply assigned to a squad, nothing else!
SoC or Struck of charge : numbers only counted until june45!

Production and active duty43 (tried another view in exell)


the same for 44:



and for 45:



So, only by numbers, i will say the k-4 is much better than the spit: there were simply more of them, and as everyone knows, quantity beats quality, look at the 262 case if you don't trust me

the spit14 has less influence on ww2 airbattles than the he-162 in my eyes!

Now, let's continu the bashing!...

[kool kitty89]

OK, Bill but what part do you still disagree with Soren about?

[Kurfürst]

Excellent graphs bada. I can confirm that bada`s strenght figures for Spitfire XIVs agree well with known number of XIVs reported in service at given dates.

Its also worth remembering that not all aircraft assigned to an RAF fighter squadron flew operational sorties; British practice was to use 20-22 plane strenght squadron establishments, of which however a maximum of 12 planes would fly operational sorties; the remaining aircraft was assigned to the Squadron as reserve aircraft.

For comparison, the 109K strenght assigned to first-line units was a steady 200 in October, November and December 1944, rising to 314 by end of January 1945; no further strenght data is available unfortunately, but its worth remembering that the production of other Bf 109 subtypes practically ceased by that time in favour of the DB 605D powered G-10 and K-4.

[drgondog]

Originally Posted by kool kitty89

OK, Bill but what part do you still disagree with Soren about?

1. His misquotes of what I said as I have noted above

2. His use of my explanations to him (Soren) to try to expand what he said to Gene as if he was the author of the thought

Notably in my last two comments in response to this one this morning.

From Soren
Bill I posted the entire mail in its original form, and all I wrote is there in the exact original context!
So stop believing I'm trying fool anyone here man! Go contact Gene for crying out loud!

For the record - I agree everything Gene said.

Soren misquoted his original comments that started this long running debate to Gene - he pulled out the original context 'of designing elliptical distribution' for a high G turn and inserted mine regarding 'aeroelastic effects combined with the tip design' were the causes of the stall.

I think I have laid out the specifics in my last three posts on this subject.

Soren has not admitted to either the 'ommissions' or the 'commisions', from his statements and my rebuttals ,in his email to Gene.

He re-wrote his statements to include my corrections and posed them as his own thoughts.

Further - he is not responding to the three simple questions I asked him about Aeroelasticity... dispite his vast knowledge of the subject before this debate.

That about sums it up.

[Hunter368]

Well at least we have it out on the table now. A starting point.

[drgondog]

I think I will take a nap... but I think I want the Spit XIV depending on the mission.

[claidemore]

Hi Bada,

Actual production of the Mk XIV Spitfire was 957, not 482. Not sure what your sources are for those figures, but they are a bit low. I have seen figures ranging from 700+ to 1500 for the K4.

Be that as it may, your graphs show an interesting trend. Nearly half of available Mk XIVs were usually non-operational, because, as pointed out by "glen" in a previous post, they simply weren't needed. The ones who were operational had a hard time finding anything to fight as it was. Too much competition from Mustangs, Tempests, Typhoons, P47s, P38s and Spit IXs.

The graphs show a peak of MkXIV use about the time the allies "knew" they would win the war, so there wasn't much sense in producing hordes of planes that weren't needed. Production and use was pretty steady all through the early months of 1945, the numbers available were fullfilling the need.

The K4 on the other hand, was needed badly. The Luftwaffe did not have the luxury of having half the supply in reserve. Still, only 314 with frontline units in January 45 (but given the fuel situation, how much flight time were they getting?). After that production fell off, as some units started reporting being given older types such as G6.

Besides, if number of planes used is the final determinant, the Yak 3 or La7 would win hands down, with numbers in the thousands compared to numbers in the hundreds.

[parsifal]

Not that it matters, but wasnt something like 80% of the LW grounded or otherwise non-operational at the end of the war, mostly due to fuel shortages, but also because of pilot deficiencies. Dont the figures for the K-4 therfore appear to be somewhat misleading from that stanpoint. Perhaps not relevant to this thread, I admit

[drgondog]

Originally Posted by parsifal

Not that it matters, but wasnt something like 80% of the LW grounded or otherwise non-operational at the end of the war, mostly due to fuel shortages, but also because of pilot deficiencies. Dont the figures for the K-4 therfore appear to be somewhat misleading from that stanpoint. Perhaps not relevant to this thread, I admit

From my perspective the Mk XIV and K-4 were both in combat and should be evaluated on merit. What is debateable is to what extent the K-4, on the average, would perform to spec versus the Mk XIV at that stage of the war given the variable supply chain for parts and fuel to keep them at 'peak performance' level

[Hop]

Its also worth remembering that not all aircraft assigned to an RAF fighter squadron flew operational sorties; British practice was to use 20-22 plane strenght squadron establishments, of which however a maximum of 12 planes would fly operational sorties;

Not strictly true. Typically only 12 would fly sorties at one time. Because some planes are always unserviceable, a German formation with 20 aircraft on strength would often only have 12 or so available for operations. Hooton gives the figures for German fighters available in the Reich and on the west Front in June 1944 as 983, with 566 serviceable. That's a 20:12 ratio, near enough.

Actual production of the Mk XIV Spitfire was 957, not 482. Not sure what your sources are for those figures, but they are a bit low.

I believe the figures are from a spreadsheet that lists all Spitfires produced. That shows 482 Spitfire "XIV". However, whoever has extracted the data from the spreadsheet has ignored Spitfire "XIVe", which is the Spitfire XIV with the "E" wing armament, 2 20mm cannon and 2 0.5 inch Brownings. There are another 44 of those.

They have also ignored the Spitfire FR XIV. That was the Spitfire XIV with a camera mounted in the rear fuselage. It was different from the unarmed photo reconnaissance Spitfires in that it retained full armament, and flew combat sorties, it just took photos at the same time.

There are another 423 "FR XIV" on the list, and 8 "FR XIVe".

That's a total of 957 Spitfire XIVs.