Draining E in turns

[gripen]

Originally posted by Crumpp
As to your C - I don't have any web space and I am not putting all my document out for public consumption yet.
 

Just do like Angus and Nashwan said or do like Isegrim and join to the X-plane.org and you have 50MB free web space.

Originally posted by Crumpp
I am however being nice enough to offer it to you and others on this BBS.

Using the free web space you can be nice for every one here, and for visitors too.

Originally posted by Crumpp
Why do you constantly take a crappy attitude?  Are you in fear for some score in the game?

Well, you own doings in the past might have something to with this. I quess no one likes if some one call him/her with harsh words.

Originally posted by Crumpp
You call into question the Oswald factor calculations and were wrong.

Well, I wonder what you mean? Please show me the mathematical relation between the e factor and the aspect ratio.

Originally posted by Crumpp
It is not just JL275, I have posted calculations for EVERY Spitfire Mk IX listed on that site.  They all confirm David Lednicers data.

Let's see, here are flat plate areas at the 1st FTH for Cd:

BF274: 5,21
BS428: 4,93
BS543: 4,46
BS551: 5,12
EN524: 5,06
BS310: 5,22
JL165: 5,34 (A&AEE)
JL165: 5,27 (RR)
MA648: 4,53
JF275: 4,93 (Spitfire VIII)

As can be seen the JL165 had the highest drag of all tested Spitfire IXs. Only the high altitude Spitfires came close, naturally because the compressibility effect. None of the results support directly Lednicer's value with default assumptions, only the Jl165 come close.

Originally posted by Crumpp
I wonder how you don't!

Well, the value is certainly much less than one quarter of the distance between 2000 and 2200 hp.
 

Originally posted by Crumpp
I wonder how you don't!

That is easy to read => 1760 ps at 2800 ft

Originally posted by Crumpp
Not according to every reference I have found on the Spitfire Mk VIII.

Just read Nashwan's post. The high altitude Spitfires had hig altitude engines (like the merlin 63 or 70) and the JF275 had the medium/low altitude Merlin 66.  

Originally posted by Crumpp
It was never deployed to the Northern European Theater.

Well, it fought well against the LW in the MTO.

Originally posted by Crumpp
Many sites agree it was the best performing Spitfire version produced...

Well, as can be seen from the flat plate comparison, the drag difference was not big between the Spitfire IX and the VIII.

Originally posted by Crumpp
...however by the time it came into service the Mk IX was well in place and it simply was not produced in any numbers.

According to your link above 1658 built and 1231 of these with the Merlin 66.

Originally posted by Crumpp
The discussion was on David Lenicers data...

Actually the discussion is about "Draining E in turns", and that is what I have been calculating.

Originally posted by Crumpp
...with your contention being the Spitfire always had less drag than the 190.  That is simply not true.  He was correct not you.

I have not made such contention but I have stated that the there appear to be no large differences in drag between the Spitfire and Fw 190.

Originally posted by Crumpp
Here is JB 275's drag numbers at 2800 feet FTH (2020hp).


Total drag = 1051.19806 @ 440 fps
parasitic drag = 972.4078707

FW-190A8

Drag total = 1112.002143@ 440 fps
parasitic drag = 981.8304509

Ah... finaly.

gripen

[Crumpp]

For the Spitfire Mk IX Merlin 61 we have in AH:

Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7480
Wing span, ft - 36.1

Step B - performance #s at a known altitude


Altitude (feet) - 15400
Maximum speed (at test alt.- mph) - 380.5
Engine Horsepower (bhp at test alt) - 1565
Stall speed (mph, at test alt) - 90

Total Drag - 795.641828 @ 440 fps

Parasitic drag - 687.4074265

FW-190A5

Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9052
Wing span, ft - 34.45

Step B - performance #s at a known altitude


Altitude (feet) - 15400
Maximum speed (at test alt.- mph) - 394
Engine Horsepower (bhp at test alt) - 1420
Stall speed (mph, at test alt) - 110

Total Drag -718.2845242@ 440 fps

Parasitic drag - 540.0383219


FW-190A8
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 196.96
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45

Step B - performance #s at a known altitude


Altitude (feet) - 2800
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 1736
Stall speed (mph, at test alt)- 110

Drag total = 1112.002143@ 440 fps
parasitic drag = 981.8304509


Spitfire Mk IX Merlin 66 (+25)
Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1

Step B - performance #s at a known altitude


Altitude (feet) - 2800
Maximum speed (at test alt.- mph) - 364
Engine Horsepower (bhp at test alt) - 2020
Stall speed (mph, at test alt) - 90

Total Drag = 1127.240025@ 440fps
parasitic drag = 1055.775

BF274: 5,21
BS428: 4,93
BS543: 4,46
BS551: 5,12
EN524: 5,06
BS310: 5,22
JL165: 5,34 (A&AEE)
JL165: 5,27 (RR)
MA648: 4,53
JF275: 4,93 (Spitfire VIII

IS NOT THE SAME AS THIS:

Gripen says:

As an example below are accelerations calculated for couple planes at 483 km/h at sea level. Note that flat plate areas are now calculated same way as in the Lednicer's paper (Cdwet includes Cdi and Cd=1 for flat plate) and thrust is calculated assuming 85% efficiency and 120 kp exhaust thrust:
Spitfire IX (average), 3400 kg, 1586 hp, flat plate area 6,18 sqft, e factor 0,9
Fw 190 (US Navy) 3940 kg, 1740ps, flat plate area 6,69 sqft,   e factor 0,8  

Which you calculated earlier in this thread at 300mph (440 fps) and have stuck too for the majority of it.  Which is contrary to David Lednicer's data.  Don't play coy, Gripen.  It is not what men do.

As for the turning issue you need check about 3 pages back.  That issue was resolved.  Again you don't bother to read responses.

According to your link above 1658 built and 1231 of these with the Merlin 66.

vs How many Spitfire Mk IX's?

Yeah and according to that link it did not see much service and NONE of them served in the Northern European theater.  
Again you do not read peoples responses and you wonder why they lose patience with you.  About 4 post's back when the subject first came up on the Spitfire Mk VIII, I commented that I hoped HTC brings it to AH.  Simply because I know there are Spitfire fans who have personal ties to the plane.  Maybe they can add the FW-190A9 as well.

 

Well, I wonder what you mean? Please show me the mathematical relation between the e factor and the aspect ratio.

It has to do with the whole LIFT thing Gripen.....Again you don't bother to read peoples response's.  It was explained by a man who teaches aeronautics!
You know the thing induced drag is a function of?

I have not made such contention but I have stated that the there appear to be no large differences in drag between the Spitfire and Fw 190.

Flat out BS.  You debunked Lednicers data from the beginining.

Ah... finaly.

Yeah and it is NOT a Spit IX.  NONE of the Spit IX's have less parasistic drag. I would be glad to go through them all and post the data.  You can look at a photo of JG275 and see why.  Guppy posted one in another thread.


 

If you've got any pics you do want to post, try picture hanger:

Thanks Nashwan!
Great info on the Spitfire too.  

Crumpp

[gripen]

Originally posted by Crumpp
IS NOT THE SAME AS THIS:

Which you calculated earlier in this thread at 300mph (440 fps) and have stuck too for the majority of it.  Which is contrary to David Lednicer's data.  Don't play coy, Gripen.  It is not what men do.

Well, my original calculations had exhaust thrust modeled as well as propeller thrust was adjusted  according to the momentary theory. Shortly, default assumptioms are different  than in the Zigrat's spreadsheet.

Originally posted by Crumpp
It has to do with the whole LIFT thing Gripen.....Again you don't bother to read peoples response's.  It was explained by a man who teaches aeronautics!

I don't see any mathematical connection between the e factor and the aspect ratio in Badboy's response which I actually quoted above.

Originally posted by Crumpp
You know the thing induced drag is a function of?

Actually I have been teaching that to you in two threads and finaly you are beginning to understand.
 

Originally posted by Crumpp
Flat out BS.  You debunked Lednicers data from the beginining.

Well, the difference in the Lednicer's values (5,22 and 5,4) is about 4%, much less than variation between various tested Spitfire IXs.
 

Originally posted by Crumpp
Yeah and it is NOT a Spit IX.  NONE of the Spit IX's have less parasistic drag.

Let's see, here are flat plate areas for Cd0 for couple tested Spitfire IX and the JF275:

JF275: 4,77
BS543: 4,34
MA648: 4,34

Some of the high altitude Spit IX might also have lower value at low altitudes.

gripen

[Angus]

Found some more of the Mk VIII.
It served in Europe, but no squadron of it operated from the UK.
There were high alt variants of them, but not with pressurized cockpits, - those were Mk VII's. Some high alt variants served in the med.
Drop tank equipped Mk VIII's roamed far north in the Italian campaign and had frequent encounters with LW's 109's and 190's.
Will post more when I find more.

[Crumpp]

don't see any mathematical connection between the e factor and the aspect ratio in Badboy's response which I actually quoted above.

"e" factor is an arbitrary value assigned IAW the tip of the wing.

Oswalds is calculated based on:

Even though it is a function of aspect ratio, sweepback angle, taper ratio and twist, the largest influence on the wing of a WWII fighter with very little sweep or twist comes from aspect ratio and taper ratio

It is calculated with a simple manipulation of this formula:

http://www.grc.nasa.gov/WWW/K-12/airplane/induced.html

To solve for "e"

Shortly, default assumptioms are different than in the Zigrat's spreadsheet.

Difference is assumptions vs. calculations.  I prefer calculations when they are available.  I just don't like to those calcs myself!

Actually I have been teaching that to you in two threads and finaly you are beginning to understand.

No, I wouldn't label it that.   You're the only one in the short time I have known you that feels that way.


I would have to say you have been a cataylst in increasing my understanding.  Because of your obvious prejudice towards the Spitfire.

Well, the difference in the Lednicer's values (5,22 and 5,4) is about 4%, much less than variation between various tested Spitfire IXs.

How does that change this:

Flat out BS. You debunked Lednicers data from the beginning.

It does not and is called "excuses".  Rather than making the point that "drag varies" among different A/C of the same type, TEACHER, you chose to argue that Lednicer was wrong, you were right, and the FW-190 is ALWAY's has more drag throughout the flight envelope.

Only when other calculations started appearing with correct values did you begin to back off that assumption.  Never did you come out and say, "this only occurs in SOME spitfires" before then.  

I will run the numbers on the other Spitfires and cross-reference with their set up's.

Which one do you guys think is most representative of the service model found in the squadrons?

Crumpp

[gripen]

I had wrong output value for the Merlin 66 so here is the corrected listing of flat plate areas for Cd0:

BF274: 4,93
BS428: 4,68
BS534: 4,70
BS551: 4,80
EN524: 4,82
BS310: 4,98
MA648: 4,69
JF275: 4,77
JL165: 5,19

Results are still the same; the BS428, BS534 and MA648 had lower flat plate area than the JF275. In addition here is corrected listing of flat plate values for Cd:

BF274: 5,21
BS428: 4,93
BS534: 4,91
BS551: 5,04
EN524: 5,06
BS310: 5,22
MA648: 4,88
JF275: 4,92
JL165: 5,34

Originally posted by Crumpp
"e" factor is an arbitrary value assigned IAW the tip of the wing.

Oswalds is calculated based on:

"Even though it is a function of aspect ratio, sweepback angle, taper ratio and twist, the largest influence on the wing of a WWII fighter with very little sweep or twist comes from aspect ratio and taper ratio"

The aspect ratio itself does not give anykind of information about the lift distribution nor exact information about the shape of the wing. I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone.

Originally posted by Crumpp
Difference is assumptions vs. calculations.  I prefer calculations when they are available.  I just don't like to those calcs myself!

Well, IMHO my original calculation is more accurate than Zigrat's because it contains exhaust thrust as well as propeller efficiency calculation based on output and size of the propeller.

gripen

[Crumpp]

The aspect ratio itself does not give any kind of information about the lift distribution nor exact information about the shape of the wing. I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone.

I highly doubt your estimated figures are nearly as accurate.  Just look at your initial conclusions about Lednicer's data.

Well, IMHO my original calculation is more accurate than Zigrat's because it contains exhaust thrust as well as propeller efficiency calculation based on output and size of the propeller.

You factor in your "guestimation".
The man that teaches aeronautics even said these calculations were much more accurate than assigning either the same or arbitrary values to the formulas.

Lets see and compare total drag @ 440fps at the Spitfires FTH altitude:

BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps

All three aircraft were flying with C.G. 5.0 in. aft of the datum, BS. 354 and BS. 543 weighing 7485 lb., and BS. 551 weighing 7470 lb.

BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)

BS543 - 810.863789
FW-190A5 - 705.7484202

BS551 -  758.4823884
FW-190A5 - 704.890256

EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376

BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689

BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496

JL165 - done to death

MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275


BS310 - 792.6552588 Parasitic drag - 691.672177

FW-190A8 - 794.3964059 Parasitic drag - 606.4158622

At 315mph the total drag situation changes completely in the FW-190A8 favor.

JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.

MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:

External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.

The RAF must have eliminated the boundary layer separation David Lednicer referred too in his article with new pattern intake.

MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067

The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.

So ONE example of the Spitfire Mk IX beats the FW-190A8 in total drag.  The others are behind their FW-190A contemporary the whole way.

That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.

Crumpp

[Crumpp]

Gripen says:
Well, IMHO my original calculation is more accurate than Zigrat's because it contains exhaust thrust as well as propeller efficiency calculation based on output and size of the propeller.

This is completely at odds with this:

Gripen says:
I wondered a bit why could not reach same numbers with Zigrat's spreadsheet as with my own.  

I asked you for a copy of your spreadsheet so we could use the same one BTW.

Only difference is on yours you guestimate the "e" factor, prop efficiency, and exhaust thrust.  

Your using an excel spreadsheet like everyone else.  It's very easy to do and the formulas are the same.  It just saves button pushing time.

Crumpp

[Badboy]

Originally posted by gripen
The aspect ratio itself does not give anykind of information about the lift distribution nor exact information about the shape of the wing. I don't see how it can be used alone to estimate the e factor. Maybe with the taper ratio but not alone.

Glauert was first to derive a theoretical expression for rectangular wings, in the form of a correction to the value for an elliptical wing. With accuracy as good as the assumptions involved in the derivation, empirical equations for Glauert’s correction yield results in good agreement with experimental values. One such equation offered by a Professor Wood, and manipulated slightly (by me) to make it more readable and easy to use, gives good agreement to flight test data for aspect ratios between 2 and 10:

e = 1/(0.9676+0.033AR)  

(The original relationship published by Wood was:   dCd/dCl^2 = 0.308/AR + 0.0105  which you read as the slope of the graph of drag against the coefficient of lift squared equals 0.308 divided by the aspect ratio plus 0.0105 I just carried out the simplification to the expression above)

You will notice that equation gives close agreement to the value used by Zigrat in his spreadsheet, which indicates that Zigrat either found another empirical formula for e based on other, slightly different data, or that he derived his empirical expression from other data available to him.

There are a large number of sources that clearly state the relationship between the efficiency factor and Aspect Ratio (AR) and several of them also provide graphs of e against AR, examples include:

Principles of Aerodynamics, by Dwinnell, page 144.  
Airplane Performance Stability and Control, by Perkins & Hage, page 73.
Elements of Practical Aerodynamics, by Jones, page 73.
 
Some others publications have multiple curves in order to include taper ratio. A readily available source, for which you can also obtain software, is:

Aerodynamics Aeronautics and Flight Mechanics, by McCormick, page 172.

Many of those sources are out of print, but should be available from university libraries, modern publications focus on other methods for calculating/estimating it, including the lift line method and computational fluid dynamics, that can then include all the other variables I mentioned in my previous post.

Hope that helps.

Badboy

[Angus]

How absolutely nice
I'll save this thread.

And Crumpp&Gripen.

Your debate has been somewhat in a frustrated tone at times. Still, all keeps going. Shake hands, and if you ever go touring, come to my place and we'll have a heck of a time

(LAN+AHII+BEER, need I say more?. Hotel facilities of course)

[Badboy]

Originally posted by Crumpp

Only difference is on yours you guestimate the "e" factor, prop efficiency, and exhaust thrust.  
Crumpp

You need to be careful if this is true because while e is constant, the prop' efficiency and exhaust thrust are not, and can vary by as much as 100% between best climb speed and the top speed used, which may lead to poor results.

Badboy

[gripen]

Originally posted by Crumpp
I highly doubt your estimated figures are nearly as accurate.  Just look at your initial conclusions about Lednicer's data.

Well, I have claimed my assumptions throughout this thread. And my initial assumption was that Lednicer's data is for the Cd0 as claimed in the J22 site. After looking Lednicer's writing I noticed that the data was for total drag.

Originally posted by Crumpp
You factor in your "guestimation".

My "questimation" uses more measurable variables than Zigrat's.

Originally posted by Crumpp
The man that teaches aeronautics even said these calculations were much more accurate than assigning either the same or arbitrary values to the formulas.

Actually "the man" edited his post and added:

"In any case, calculating the Oswald efficiency factor from wing geometry is problematic."

Which I believe is true. In the Zigrat's spreadsheet the e factor simply decreases when the aspect ratio increases. So far I have not yet seen any physical explanation why it should be that way and as far as my limited knowledge goes, there should be no way to estimate e factor from the aspect ratio only.

Originally posted by Crumpp
Lets see and compare total drag @ 440fps at the Spitfires FTH altitude:

BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps

So now you bring in the Fw 190A-5 data which is for unknown reason about 20-30 km/h faster at low altitude than US navy data and the Fw 190A-8 data. Just like in the case of the Fw 190A-8 we have no evidence that the A-5 data set is flight tested but the difference is that the A-8 set seems to be realistic given the used ratings and special finish but the A-5 set low altitude performance seems to be far in the unrealistic side.

Originally posted by Crumpp
MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:

"External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake."

The RAF must have eliminated the boundary layer separation David Lednicer referred too in his article with new pattern intake.

Well, as usual it would help a lot if you actually understand what Lednicer says; he talks about the radiator intakes not about the engine air intake.

Originally posted by Crumpp
This is completely at odds with this:

Actually it was very easy to do a crosscheck; I simply put exhaust thrust to zero and adjusted propeller efficiency and e factor to the same as in the Zigrat's sheet. In couple seconds I found out that results do not match and after that it took just couple minutes to find out with crosschecking what caused the difference.

gripen

[gripen]

Badboy,
I quess very high aspect ratio wing, say AR over 10, can't reach elliptical lift distribution. But in the case of the WWII fighters aspect ratios are all in the same ball park, say AR around 5-8 and I don't see reason why a generalized formula should give realistic estimate for the e factor.

Regarding Oswald,  I dug out his report  and his analyses seem to based on empirical data.

gripen

[Crumpp]

Thanks Badboy!  Great explainations.

Gripen says:
Well, I have claimed my assumptions throughout this thread. And my initial assumption was that Lednicer's data is for the Cd0 as claimed in the J22 site. After looking Lednicer's writing I noticed that the data was for total drag.

Yeah it seems to change to whatever supports your position the best.

Gripen says:
My "questimation" uses more measurable variables than Zigrat's.

Please explain.  And while you're at it lets have full disclosure on your data.  I would be glad to post ALL the data from the Spit Mk IX vs. FW-190 comparison.  Only reason I did not is because you complained that it was too detailed and unnecessary.

Badboy says:
There are a large number of sources that clearly state the relationship between the efficiency factor and Aspect Ratio (AR) and several of them also provide graphs of e against AR, examples include:

Sounds cut and dry. Good explanation.

Gripen says:

So far I have not yet seen any physical explanation why it should be that way and as far as my limited knowledge goes, there should be no way to estimate e factor from the aspect ratio only.

See above quote.

So now you bring in the Fw 190A-5 data which is for unknown reason about 20-30 km/h faster at low altitude than US navy data and the Fw 190A-8 data. Just like in the case of the Fw 190A-8 we have no evidence that the A-5 data set is flight tested but the difference is that the A-8 set seems to be realistic given the used ratings and special finish but the A-5 set low altitude performance seems to be far in the unrealistic side.

1.  Have you thought about the fact the US Navy data is in Nautical miles?

2.  No Gripen I compared the fighters with the adversary they encounter over the skies of Europe.  The FW-190A8 was not flying in 1942-3 when most of the test's occurred.  I compared it with the 1944 versions it might have encounter.  In each case the Focke Wulf had less parasitic drag, which makes sense given the manner, the two aircraft fought one another.  The Spitfire in the horizontal and the FW-190 in the vertical.  With neither able to gain a decisive advantage on the other aircraft.  Pilot skill decided the outcome.  Just like Eric Brown says "They remained about as equal as two fighters can get throughout their development."

The data is flight test, no doubt.  As far as the "filled and polished" FW-190A8 I was wrong in my translation.  It does not say "Surface fixed and painted" in German.  It says "Surface primed and painted".  The root word for "fixed," "prepared", "spackled" as are all the same in German so it is easy to see the translation error.  However the modifying articles definitely referring to "primed" in the case of painting.  Got to love how the Germans link old words to form new ones!

Gripen says:
My "questimation" uses more measurable variables than Zigrat's.

 

Badboy says:
You need to be careful if this is true because while e is constant, the prop' efficiency and exhaust thrust are not, and can vary by as much as 100% between best climb speed and the top speed used, which may lead to poor results.

Gripen says:
 thrust is calculated assuming 85% efficiency and 120 kp exhaust thrust:

Gripen says:
Well, assumptions are mostly same for all compared planes so relative results should be comparable. The only difference is the e factor which according to Lednicer is better in the Spitfire than in other two .

I have noted that Lednicer's data seems to at least partially wrong. So far I have not found real world tested data which supports assumption that the Fw 190 had signifigantly lower drag than the Spitfire.

That is because when you are presented with the test's you deny they existed.  Even when backed up by mathematical analysis and the historical logs.

In fact the numbers calculated on Zigrat's spreadsheet very closely match Lednicers findings to a tee.

Crumpp

[Crumpp]

This report presents general formulas for the determination of all major airplane performance characteristics. A rigorous analysis is used, making no assumption regarding the attitude of the airplane at which maximum rate of climb occurs, but finding the attitude at which the excess thrust horsepower is maximum. Equations and charts are developed which show the variation of performance due to a change in any of the customary design parameters. Performance determination by use of the formulas and charts is rapid and explicit. The results obtained by this performance method have been found to give agreement with flight tests that is, in general, equal or superior to results obtained by present commonly used methods.  

Nice report Gripen.  Thanks for finding it!

Crumpp