Spitfire Mk.XIV vs P-51D Mustang

Kurfürst · Oct 2, 2008

Hop said:
Note the different speeds used for the different aircraft in the table Kurfurst posted. The 109s are at significantly lower speeds than the others:

109G - 615 miles in 3.1 hours - 198 mph
LF IX - 420 miles in 1.6 hours - 263 mph
XIV - 500 miles in 1.8 hours - 278 mph
Temp - 760 miles in 3 hours - 253 mph
Must - 890 miles in 3.6 hours - 247 mph

Note that there is no correllation between range and the endurance time figures because best range is achieved at different speeds and engine settings. You are not getting max endurance at the best speed for max. range and vica versa.

There are three possibilities. One is that engineers in Britain were not adept at comparing like with the like (unlikely).

The second is that we have good old Hop, is having one of his 'ultra' days and worked himself up again on the fact that Spitfires - which he recently expressed as being perfectly capable of getting Berlin and back - were short ranged, 109s were not so short ranged, others even less short ranged and he tossed a smokescreen to muddy the water.

There's a third possibility, too. That is that Hop is right, and the 109s range is given at 198 mph. The German range tables give the 109s best cruise speed for maximum range as 410 km/h (255 mph). That would mean the 109 is actually cruising at less than optimum range and that at optimum speed (255 mph) it would have even greater range.

The truth is, of course, that Hop again finds the facts presented by the real world and real engineers disturbing, and he tries to erect a smokescreen around it.

claidemore · Oct 2, 2008

KrazyKraut said:
I already said that abouth MkIX if you read my post. And the Mustang III didn't enter service until late 43, 5-6 months after the G-6.

Yes I read your post, that's why I said "as well as the Mk IX".

The 109 G-6 was still being built till mid 1944, the AS and AM engines came out in 1944 in the G-6, and the G-6 was only approved for 1.42 ata just before the time the Mustang III came into service. The G-14 which came out in mid 1944 was basically a G-6 wth an attempt to standardize production and reduce the number of variations (reduced from a dozen to four). The different engined G-10 didn't come out till the Mustang III had been in service for almost a year. Also, G6's were used right up till the spring of 1945, being re-issued to Jg units as supplies of the newer models were not available.
So as far as combat encounters, the Mustang Mk III/P51-B/C and 109G6 were definately contemporary.

drgondog · Oct 2, 2008

Soren said:
But as we both know wing loading doesn't matter, it is lift-loading which counts.

??? are you referring to lift distribution?

KrazyKraut · Oct 2, 2008

claidemore said:
Yes I read your post, that's why I said "as well as the Mk IX".

The 109 G-6 was still being built till mid 1944, the AS and AM engines came out in 1944 in the G-6, and the G-6 was only approved for 1.42 ata just before the time the Mustang III came into service. The G-14 which came out in mid 1944 was basically a G-6 wth an attempt to standardize production and reduce the number of variations (reduced from a dozen to four). The different engined G-10 didn't come out till the Mustang III had been in service for almost a year. Also, G6's were used right up till the spring of 1945, being re-issued to Jg units as supplies of the newer models were not available.
So as far as combat encounters, the Mustang Mk III/P51-B/C and 109G6 were definately contemporary.

The numbers in question were certainly neither from G-6/AS nor G-10 or G-14, thus the point stands.

Kurfürst · Oct 2, 2008

claidemore said:
Yes I read your post, that's why I said "as well as the Mk IX".

The 109 G-6 was still being built till mid 1944, the AS and AM engines came out in 1944 in the G-6, and the G-6 was only approved for 1.42 ata just before the time the Mustang III came into service. ... The different engined G-10 didn't come out till the Mustang III had been in service for almost a year.
... Also, G6's were used right up till the spring of 1945, being re-issued to Jg units as supplies of the newer models were not available.
So as far as combat encounters, the Mustang Mk III/P51-B/C and 109G6 were definately contemporary.

Mike Williams 'stuff', eh?

1, DB 605A was cleared for 1,42ata MAP in October 1943.
2, What's the big deal of the G-10 of October 1944, it had the same performance as the G-6/AS with MW as of April 1944...
3, As of the 'G-6s in 1945' Mike 'Bullshit' Williams topos, certainly there were G-6s around - 76 being reported on the end of January 1945 out of 1435 first line 109s, the rest being G-10/-14/K-4 - their equipment state is a different matter, as its impossible to tell how many were retrofitted with MW-50 boost effectively making them G-14s by this time. And, series production by that time was practically limited to G-10/K-4.

I am quite willing to bet there were more Mk V Spitfires in the RAF than G-6s in the Luftwaffe. Which, from the orders of Battles I have seen, holds true also for the start of 1944...

Thing is the most commonly place aircraft at the start of 1944 were the Mark V Spitfire, the Typhoon, the P-47, the Bf 109G-6 and the FW 190A-5/A-6. Sure the Mustang, Spitfourteens and G-6/AS and all the other flashy jet stuff was contemporary too, but just too small in numbers.

Soren · Oct 2, 2008

drgondog said:
??? are you referring to lift distribution?

No, lift-loading pure and simple. It's a common expression within aerodynamics.

Wing loading is simply weight divided by wing area, while lift-loading is weight divided by wing area and then divided by the lift coefficient in order to get the true difference. (That is the point of establishing the coefficients, they are efficiency indicators)

Wing-loading, while the prefered way for the amateur to compare a/c, is very misleading for comparative purposes as obviously different wing airfoil designs will perform differently in terms of lift drag production. Dividing the wing-loading with the lift coefficient eliminates the inherent inaccuracy of wing-loading as a comparative method and gives us the lift-loading which is completely accurate as it is based on a proportional efficiency factor established by extensive windtunnel lab test results on the particular wing.

It is for example the Fw-190's lower lift-loading which allowed it to outturn the P-51, despite the wing loading actually being higher, all thanks to the 190's high lift NACA 23000 series airfoil. The P-51's airfoil prioritized low drag instead of lift, featuring a sharp leading edge and a greatly retracted maximum chamber point, and thus it suffered in terms of lift production at the AoA's commonly reached in turns. (Lower Clmax)

drgondog · Oct 2, 2008

Soren said:
No, lift-loading pure and simple. It's a common expression within aerodynamics.

In what field of aero are you referring to Lift Loading as a 'common expression'?? Try searching for it.

Wing loading is simply weight divided by wing area, while lift-loading is weight divided by wing area and then divided by the lift coefficient in order to get the true difference. (That is the point of establishing the coefficients, they are efficiency indicators)

For level flight Weight is a vector equal and opposite to Lift. Wing Loading is correct as you stated above but further dividing Lift/Area by CL makes no sense and certainly has nothing to do with 'efficiency'. CL is only a useful way of reducing comparative differential pressure distribution at a particular velocity, density and angle of attack to non dimensional value...

CL is a non dimensional coefficient and has most relevance for two dimensional wing sections in which the Chordwise velocity is only measurement or in the case of three dimensional wings it is dominant velocity when compared to span wise vector....In other words level - not rolling or sideslip motion, with no provision for three dimensional effects of wing shape, aspect ratio, tip to root chord ratio, twist, surface roughness, etc

In what way do you propose that L/A further divided by CL in any way compares 'efficiency'? You would be saying that an aircraft with same WL but lower CL to another a/c is somehow more 'efficient'??? Efficient in what way? Source for this please?

WL= Wt/A = Lift/Area = Cl*(1/2*rho*V>>2)*Area)/Area= CL*q = WL

WL/CL=q -----> so a measure of efficiency is q?

Coefficients eliminate need for units of measure and reduces to non dimensional comparisons. Lift (unit of force) divided by Drag (unit of force) is then a non dimensional coefficent of comparison between different aircraft. Striving for high CL/CD is important for range and payload design

Wing-loading, while the prefered way for the amateur to compare a/c, is very misleading for comparative purposes as obviously different wing airfoil designs will perform differently in terms of lift drag production.

This is true - as I have said before, and you argued otherwise - there are a lot of arcane factors affecting the accuracy of turn/maneuver comparisons - why have you now come to the 'dark side'??

Although 'very misleading' is not a term I would use. I would say "difficult to express in absolutes' but I would further say that the lower wing loaded airframe - all else absolutely equal would turn tighter than the heavier a/c. The only way to get a true comparison of this is to take the exact same airframe and load one to a heavier take off weight. Everything beyond this comparison is much more difficult to achieve a model matching reality.

Further, when discussing the analytics of manuevering a/c, the total drag (i.e parasite drag components and induced drag), spanwise flow distribution, aeroelastic effects and power available to power required become important factors alonside WL and CL and CD in striving for a comparison.

Dividing the wing-loading with the lift coefficient eliminates the inherent inaccuracy of wing-loading as a comparative method and gives us the lift-loading which is completely accurate as it is based on a proportional efficiency factor established by extensive windtunnel lab test results on the particular wing.

This might be a misunderstanding on your part - but it ain't true in any literature I have ever seen - My first reaction is to sound the BS horn, but second one is to ask you to point me to a source to see if you understand what you just stated?

It is for example the Fw-190's lower lift-loading which allowed it to outturn the P-51, despite the wing loading actually being higher, all thanks to the 190's high lift NACA 23000 series airfoil. The P-51's airfoil prioritized low drag instead of lift, featuring a sharp leading edge and a greatly retracted maximum chamber point, and thus it suffered in terms of lift production at the AoA's commonly reached in turns. (Lower Clmax)

Soren, simply 'no' - this is nonsense...with one exception and that is that both of these birds were in serious danger of stall at low speed/high AoA, one more violently than the other.

claidemore · Oct 3, 2008

Kurfürst said:
Mike Williams 'stuff', eh?
Nope, Wiki!
1, DB 605A was cleared for 1,42ata MAP in October 1943.
Yes, just before the Mustangs came into service, which is what I said.
2, What's the big deal of the G-10 of October 1944, it had the same performance as the G-6/AS with MW as of April 1944...
I don't think it's a big deal at all, just something to mention.
3, As of the 'G-6s in 1945' Mike 'Bullshit' Williams topos, certainly there were G-6s around - 76 being reported on the end of January 1945 out of 1435 first line 109s, the rest being G-10/-14/K-4 - their equipment state is a different matter, as its impossible to tell how many were retrofitted with MW-50 boost effectively making them G-14s by this time. And, series production by that time was practically limited to G-10/K-4.
I never said otherwise, I just said that the G6's were in use in 1945, thats all. Wasn't trying to infer that they were common, or the primary opponent.

I am quite willing to bet there were more Mk V Spitfires in the RAF than G-6s in the Luftwaffe. Which, from the orders of Battles I have seen, holds true also for the start of 1944...
As I pointed out to you in a thread quite some time ago, no Mk V's were used in combat in Europe in 1944, they were only used in Great Britain in reserve units and units rotated to the rear. Front line units flew Mk IXs.

Thing is the most commonly place aircraft at the start of 1944 were the Mark V Spitfire, the Typhoon, the P-47, the Bf 109G-6 and the FW 190A-5/A-6. Sure the Mustang, Spitfourteens and G-6/AS and all the other flashy jet stuff was contemporary too, but just too small in numbers.

I agree with the other planes, but not with the Mk V being most common, the Mk IX was the most common Spitfire 'in combat' in early 1944. Sorry but the theory on the Mk V being the most common type in combat late war just doesn't hold water. If you don't believe me you can ask "Bullshit Williams" or "Smokescreen Hop".

claidemore · Oct 3, 2008

KrazyKraut said:
The numbers in question were certainly neither from G-6/AS nor G-10 or G-14, thus the point stands.

I guess I gotta go back to school and learn to write so's folks can understand me.
My point was that the standard engined G6 would have been commonly encountered by Mustangs until mid 1944. AS engined G6's started production in April 44,(as pointed out by Kurfurst) but it takes time for that production to replace all the 'old' G6's in service. Therefore if the numbers in question are from a standard engined 109G-6, they have relevance.

Kurfürst · Oct 3, 2008

claidemore said:
I agree with the other planes, but not with the Mk V being most common, the Mk IX was the most common Spitfire 'in combat' in early 1944. Sorry but the theory on the Mk V being the most common type in combat late war just doesn't hold water. If you don't believe me you can ask "Bullshit Williams" or "Smokescreen Hop".

The following is from a British paper titled 'PROGRAMME FOR RE-EQUIPMENT OF DAY FIGHTER-TYPE SQUADRONS'

Force as at 1 Jan 1944:

Spitfire V - 24 Sqns.
Spitfire VII - 2 Sqns.
Spitfire IXF - 11 Sqns.
Spitfire IXHF - 0 Sqns.
Spitfire IXLF - 9 Sqns.
Spitfire XII - 2 Sqns.
Spitfire XIV - 0 Sqns.
Typhoon - 19 Sqns.
Whirlwind - 1 Sqn.
Spitfire XI - 1 Sqn.
Mosquito IX - 1 Sqn.
Totals: 86 Sqns.

During the month it changed somewhat, ie. by 31 Jan 1944 it was 3 Mustang III, 21 Spitfire V, 5 IXF, 19 IX LF etc.

Still it would appear to me Mk Vs were very much present, which is no particular surprise given the low production number of IXLFs in 1943.

PS: The /AS version 109s were produced from December 1943 (but only two of them, probably the protos, so production is really from January), they were being sent to the Gruppen since April 1944, at least March/April is the first month I know they are mentioned.
But basically you are right in that Mustangs commonly encountered G-6s well until the 2nd half of 1944. OTOH I believe G-6s would encounter P-47s and P-38s more commonly than Mustangs.

Soren · Oct 3, 2008

Bill,

What part about this is nonesense??:

"Lift coefficient may be used to relate the total lift generated by an aircraft to the total area of the wing of the aircraft."

Weight / Wing area = Wing loading:
4000 kg / 22 m^2 = 181.18 kg/m^2
Weight / Wing area / CL = lift-loading:
4000 kg / 22 m^2 / 1.6 = 113.63 kg/m^2

A lower Cl equals a higher lift-loading and vice versa, everything else being equal.

Example:
4000 kg / 22 m^2 / 1.3 = 139 kg/m^2
4000 kg / 22 m^2 / 1.5 = 121 kg/m^2

So how exactly do you figure that to be the lower the Cl the more efficient the a/c is ? What are you talking about Bill ? It is you who isn't making any sense.

The lift coefficient (Cl) is an efficiency indicator of lift production as it tells us how efficient a wing is at producing lift pr. surface area. As we both know different airfoil wing designs produce different amounts of lift drag, thus the need for the Cl.

That having been said we know the Clmax of both the Fw-190's P-51's wing, 1.58 1.35 respectively, both figures established in extensive windtunnel tests. The Fw-190's high Clmax stems mainly from its choice of airfoil, the high lift NACA 23000 series.

It is the lower lift-loading of the Fw-190 which allowed it to turn better than the P-51, the Fw-190's wing generating more lift pr. wing surface area:

4,575 kg / 21.64 m^2 / 1.35 = 156.6 kg/m^2
4,270 kg / 18.30 m^2 / 1.58 = 147.6 kg/m^2

kool kitty89 · Oct 3, 2008

Kurfürst said:
The following is from a British paper titled 'PROGRAMME FOR RE-EQUIPMENT OF DAY FIGHTER-TYPE SQUADRONS'

Force as at 1 Jan 1944:

Spitfire V - 24 Sqns.
Spitfire VII - 2 Sqns.
Spitfire IXF - 11 Sqns.
Spitfire IXHF - 0 Sqns.
Spitfire IXLF - 9 Sqns.
Spitfire XII - 2 Sqns.
Spitfire XIV - 0 Sqns.
Typhoon - 19 Sqns.
Whirlwind - 1 Sqn.
Spitfire XI - 1 Sqn.
Mosquito IX - 1 Sqn.
Totals: 86 Sqns.

I thought the Whirlwind was retired in 1943.

drgondog · Oct 3, 2008

Kurfürst said:
PS: The /AS version 109s were produced from December 1943 (but only two of them, probably the protos, so production is really from January), they were being sent to the Gruppen since April 1944, at least March/April is the first month I know they are mentioned.
But basically you are right in that Mustangs commonly encountered G-6s well until the 2nd half of 1944. OTOH I believe G-6s would encounter P-47s and P-38s more commonly than Mustangs.

The encounters with P-38s would be in the same areas as Mustangs as both were used exclusively for target escort, relegating the P-47s (and Spitfires) to Penetration and Withdrawal duties due to lack of range. So, basically all the units east of Frankfurt would be dealing primarily with Mustangs and P-38s.

drgondog · Oct 3, 2008

Soren said:
Bill,

What part about this is nonesense??:

"Lift coefficient may be used to relate the total lift generated by an aircraft to the total area of the wing of the aircraft."

True - this is not nonsense

Weight / Wing area = Wing loading:
4000 kg / 22 m^2 = 181.18 kg/m^2
Weight / Wing area / CL = lift-loading:
4000 kg / 22 m^2 / 1.6 = 113.63 kg/m^2

Weight/Wing Area = Wt/A = Lift/Wing Area = L/A

Lift = L = Cl*q*Wing Aea = L

(L/Wing Area)/Cl = q= 1/2*rho*V>>2

in what manner of analysis would you offer dynamic pressure as an 'efficiency'?

The lift coefficient (Cl) is an efficiency indicator of lift production as it tells us how efficient a wing is at producing lift pr. surface area. As we both know different airfoil wing designs produce different amounts of lift drag, thus the need for the Cl.

Interesting, true and irrelevant to your thesis

That having been said we know the Clmax of both the Fw-190's P-51's wing, 1.58 1.35 respectively, both figures established in extensive windtunnel tests. The Fw-190's high Clmax stems mainly from its choice of airfoil, the high lift NACA 23000 series.

It is the lower lift-loading of the Fw-190 which allowed it to turn better than the P-51, the Fw-190's wing generating more lift pr. wing surface area:

Interesting but unproven and your 'analysis' doesn't prove it

Seriously, where did you discover 'Lift Loading' as a concept - I actually would like to see the analysis??

Timppa · Oct 3, 2008

Kurfürst said:
...As of the 'G-6s in 1945' Mike 'Bullshit' Williams topos..

Is it possible to keep the discussion civil ?
This is the absolutely the best and most knowledgeable forum on WW2 aircraft that I have seen yet. Let's keep it that way.

DerAdlerIstGelandet · Oct 3, 2008

I will say this for the last time! I have said this many times in other threads. So have other moderators. Everyone seems to enjoy ignoring it. No more!

If I read another bullshit remark about Mike Williams, the person who said it will no longer post in this forum.

Mike Williams is not here to defend himself. Talking about someone like that is cowardly in my opinion. Let alone childish!

If you disagree with Mike Williams, that is fine. You can discuss it here, but you can do so in a civil manner.

Is that clear to everyone?

drgondog · Oct 3, 2008

soren - let's not de rail this on aero. Take it to performance thread

Soren · Oct 3, 2008

Interesting but unproven and your 'analysis' doesn't prove it

Bill how does my analysis not prove it ???

To do an accurate comparison you HAVE to know the Clmax and you HAVE to divide the wing-loading with it. Why ? Because it's a coefficient, it's meant to tell you how efficient the wing is at providing lift pr. surface area.

So if the wing of aircraft A has a lift coefficient which is 30% higher than that of aircraft B, then aircraft B's wing provides 30% more lift for every square cm, m, foot etc etc than the wing of aircraft A. The very purpose of Cl as an efficiency indicator.

drgondog said:
Seriously, where did you discover 'Lift Loading' as a concept - I actually would like to see the analysis??

Bill it is so very commonly referred to by a lot of people, also NASA. Try asking Gene as-well, I doubt he will have any objections with the term.

Try typing lift-loading + wing-loading on google.

Soren · Oct 3, 2008

drgondog said:
soren - let's not de rail this on aero. Take it to performance thread

Not sure we're derailing anything here, but where's the performance thread ?

drgondog · Oct 3, 2008

Soren said:
Bill how does my analysis not prove it ???

To do an accurate comparison you HAVE to know the Clmax and you HAVE to divide the wing-loading with it. Why ? Because it's a coefficient, it's meant to tell you how efficient the wing is at providing lift pr. surface area.

Soren - I googled Lif Loading and Lift-loading and got nothing. I haven't been active in Aero research papers but have never heard of 'lift loading in context of efficiency"

Having said that when you do the math WL/CL = q

So if the wing if aircraft A has a lift coefficient which is 30% higher than that of aircraft B, then aircraft B's wing provides 30% more lift for every square cm, m, foot etc etc than the wing of aircraft A. The very purpose of Cl as an efficiency indicator.

CL is simply a non dimensional coefficient, obtainable from two dimensional wing sections and later tweaked via wind tunnel testing to validate the three dimensional effects. As you know the slopes are essentially constant (but different from each other) with different stalling 'breaks' at max CL to AoA and different intersect points at zero AoA and zero CL.

For three dimensional wings the slope of the CL to AoA increases with AR and also, to a smaller degree with tip chord ratios.. etc, etc.

Having said this CL = Lift (or weight in steady flight)/(q*Awing) where q = 1/2*rho* V>>2 (the dynamic freestream pressure)

Bill it is so very commonly referred to by a lot of people, also NASA.

Try typing lift-loading + wing-loading on google.

Didn't find it, haven't heard it, math says WL/CL = q so it ain't non dimensional, it's a force divided by an area..

If two different ships are at same velocity and altitude we could say WL1/CL1 is proportional to WL2/CL2.. so extend your thesis from there? Clearly if WL1 > WL2, then CL1 has to be greater than CL2 for this equality to exist... but I can't see what you can say about comparing an Fw 190 to a P-51 based on WL1/CL1=q

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