Spit 5

[gripen]

Crumpp,
Just study your own links above. Skin friction  drag and form drag increase when the speed increases.Therefore WWI fighters could not reach Mach 1 (among other reasons).

In the case of the induced drag the situation is more complex. Certainly at given angle of attack the lift (roughly) quadruples when the speed doubles. But to fly a plane needs constant amount  lift so angle of attack (note relation to lift coefficient) can be decreased when the speed increases. Therefore induced drag decreases when the speed increases. Just look drag calculation and how lift coefficient affects induced drag.

gripen

[Nashwan]

That is a nice chart. Notice it starts at 340mph and the FW 190A8 bottoms out at 350mph at Sea Level.

These Spits are all running at 18 lbs boost, at 25 lbs they have an extra 300 hp or so, pushing the sea level speed up to almost 360 mph.

Yes, at 8000-15,000 Ft ASL and Above 25,000 Ft. Seems the sky is pretty evenly divided with each plane getting a big chunk. Very similar circumstances exist for the Spitfire Mk IX Merlin 66 vs FW-190A8.

At 18 lbs yes. At 18 lbs, the Spit LF IX and 190 are nicely matched, though I'd still prefer the Spit.

At 25 lbs, the Spit is overmatched against these 190s. (Note, I don't know about the A9 and the possible performance gains that had)

1. The Horsepower increase in the Merlin 66 is right on par with Horsepower increase of the BMW 801D2. Both engines increase the same amount in available power. Check out the chart on the website I provided. 1800 hp @ 1.42ata at 2700U/min. Most sources quote between 1950 hp and 2050 hp at 1.58ata/1.65ata.

As I said, I'm not sure on 190s, so to try to get this straight:

1.42 ata = 1800 hp
1.65 ata = 2000 hp approx

Faber's 190 was run at 1.42 ata against a Spit F IX putting out about 1580 hp, the LF IX at 18 lbs puts out about 1780hp, and the LF IX at 25 lbs puts out just over 2000 hp.

You're looking at the 190 gaining 200 hp after that test, the LF IX gaining 200 hp, the LF IX at 25 lbs gaining nearly 500 hp.

As a percentage increase, it's even better for the Spit. 1800 - 2000 hp isn't going to make as much difference as 1580 - 1780 hp.

It does NOT decrease with speed. If it did WWI biplanes would have broken the sound barrier long ago.

Induced drag decreases with speed. Remember, the lift required reamins the same, so as speed decreases angle of attack decreases, and induced drag decreases sharply.

[VO101_Isegrim]

Speaking of Faber`s 190A, I doubt it performed anywhere near it should have. Of all flight test performed, Faber`s plane is the slowest of them all.

Flight test at Rechlin showed 525 km/h at SL, and 650 km/h at 6.4km for BMW 801C powered 190As. Yet AFDU trials show little difference between between the F. MkIX and his 190A. The Brit tested performance is nowhere near of performance obtained in US tests in 1.42ata either, or FW`s own specification for the similiar A-5 at 1.42ata.

I can only guess the reasons for this, but Faber`s plane was probably in rather poor conditions. It was taken apart to the last screw for inspections, that put together, and was serviced by a groundcrew who had no idea of the FW 190 itself. The engine was running rough all the time, and there was trouble with the spark plugs. The latter makes me think the Brits didn`t feed it with good enough fuel. They only had Brit 100 grade fuel, which was quite a bit worser than the German C-3 the BMW 801D required, C-3 being more of an equivalent of Allied 150 grade fuel than 100 grade at rich mixture due to it`s high aromatic content.

[Nashwan]

Faber's 190 was run at 1.42 ata for 3 mins, and 1.35 ata for 30 minutes.

The correct ratings for it were 1.35 ata for 3 mins, and 1.42 ata shouldn't have been used at all.

It's little wonder it ran roughly.

[MiloMorai]

This is what Butch had to say about German fuel

"the B4 was roughly equivalent to 92okt and the C3 to the 100/130 US fuel. The German chose to increase CR rather than the boost, the C3 being able to sustain very high pressure (around 20atm and more with MW-50).
The result where a capability to preserve a medium boost (1.7ata) at quite a high altitude. But when a need for high boost pressure arose the German superchargers (as fitted in the DB605D) proved not up to par with Allied ones."

[Crumpp]

Gripen,

It is black and white.  NASA says different.  Your looking at the formula for computing Induced drag.  What you don't seem to realize is that basic drag, The "D" in that formula is function of velocity and is computing by multiplying "velocity squared".

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

So you double the velocity you quadruple the drag.


You seem to think I am basing this off of INDUCED drag alone?   The BASIC drag coefficient was higher in the Spitfire.  The wing aspect ratio was higher in the 190.  Therefore it suffers less from induced drag exponentially.  The Spitfire wing generated a ton of excess lift AND drag.  With velocity the drag quadruples, Therefore it took more thrust to overcome that drag.  Therefore the spitfire was NOT a great zoom climber nor did it accelerate quickly.  Again both Science and History back this up.

The FW-190 has a higher wing aspect ratio and a lower drag co-efficient.

The Spitfire has a lower wing aspect ratio and a higher drag co-efficient.

Do the math.  There is no way to get around it.  It took more than an improvement in power to weight for the Spitfire to dominate the 190A.  The added weight of the Mk XIV added the inertia the Spit needed to overcome it's drag and zoom/dive with a 190.  The Merlin powered spits simply did not have it.

These Spits are all running at 18 lbs boost, at 25 lbs they have an extra 300 hp or so, pushing the sea level speed up to almost 360 mph.

According to the HP chart for the Merlin 66 (+25) only gives a 200 hp boost for the Spit AT FULL THROTTLE HEIGHT.  
Which is right on par with the BMW-801D2 @ 1.65ata.
Please compare them yourself:

http://www.fourthfightergroup.com/eagles/jl165.html

http://www.terra.es/personal2/matias.s/fw190.htm

Make sure you use a straight edge and take some time to get the units correct for the graph squares.  The figures are that close.

Your looking at the AVERAGE increases in speed not the actual increase in speed.  The Spitfire needed that boost to stay competitive with the 190A5 and later variants able to run 1.58/1.65ata.

Only a few altitudes are they using (+18) boost.  I used the (+25) boost in my comparison.  The FW-190A8 and the Merlin 66 (+25) trade off speed advantages depending on altitude on about the same level as Faber 190A3 vs. Merlin 61 Spit.  The speed differences are also on par with the 1942 test.  None of them are over a few miles an hour.  Make sure you are comparing proper altitude and speed.  Don't compare IAS to TAS for example or a speed at 2000 ft with one at sea level.

All in all the results are the same.  The FW-190A8 and the Spitfire Mk IX Merlin 66 (+25) are about as evenly matched as planes can get.  Each would retain its traditional advantages over the other.
Crumpp

[Crumpp]

BTW:

The efficiency factor of the ellipitical wingtip of the Spitfire was 1.0.

The effciency factor of a square (least efficient) is 0.7.

NACA 23009, the FW-190 wingtip, was not square.

The formula is:

 The derivation of the equation for the induced drag is fairly tedious and relies on some theoretical ideas which are beyond the scope of the Beginner's Guide. The induced drag coefficient Cdi is equal to the square of the lift coefficient Cl divided by the quantity: pi (3.14159) times the aspect ratio AR times an efficiency factor e.

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

The efficiency can effect the outcome however I do not see where it would make a huge difference.  Especially given the Aspect ratio.  I will bet the FW-190 and the Spit have very similar induced drag.  Infact Mathmatically taking a worst case and the efficiency is .7, the FW-190 still comes out ahead with it's better aspect ratio.

Crumpp

[gripen]

Crumpp,
Actually it's fairly easy to calculate induced drag coefficients (Cdi) for the Spitfire and the Fw 190. First we need lift coefficients (Cl) for couple speeds as described here. For demonstration purposes I use 200km/h (55,56m/s) and 600km/h (166,67m/s) at sea level (density 1,229kg/m3). Other values for calculation are here:

Spitfire IX
Wing area: 22,48m2
Wing span: 11,23m
Aspect ratio: 5,61
Weight: 3400kg
Lift: 33354N
=>
200km/h Cl=0,782
600km/h Cl=0,086

Fw 190A-5
Wing area: 18,50m2
Wing span: 10,50m
Aspect ratio: 5,96
Weight: 3850kg
Lift: 37768,5N
=>
200km/h Cl=1,076
600km/h Cl=0,120

Induced drag coefficients can be easily calculated by using the formula from your  link above, note that I use same efficiency factor 0,9 for both planes despite Spitfire apparently was better in that area:


Spitfire IX
200km/h Cl=0,782 Cdi=0,0386
600km/h Cl=0,086 Cdi=0,000476


Fw 190A-5
200km/h Cl=1,076 Cdi=0,0688
600km/h Cl=0,120 Cdi=0,000849


Results are clear; the induced drag decreases when the speed increases and the Spitfire actually has clearly lower induced drag than the Fw 190. Shortly your theory on zoom climb differences is total nonsense.

Regarding the total drag, there is not much difference between these planes; at about same output the speed of the planes is about same.

gripen

[Crumpp]

According to the calculations here:


http://www.aa.nps.navy.mil/~jones/online_tools/panel2/

Simply input the NACA airfoils for the wing.

FW-190A

Root - NACA 23015

Tip - NACA 23009

Spitfire

Root - NACA 2213

tip - NACA 2209

Wing aspect ratio for the FW-190A8 is 6.0 not 5.96.  This will figure out the CL at different angles of attack.

In the wing tips there is a .0003 difference in favor of the Spitfire.  Increase the angle of attack and the difference becomes even smaller favoring the Focke Wulf.

However If you compare the wing roots, you find the opposite is true.  Increase the angle of attack and the Spitfire has large disadvantage in drag.

That .0003 is not quite enough to overcome the Basic Drag disadvantages of the Spitfire.
 
Again you seem to think induced drag and basic drag are the same thing.  You cannot get around the fact the Spitfire has more BASIC DRAG which quadruples with velocity.  

The wing tips where the most efficient design to reduce induced drag.  They are a great attempt to overcome the drag problem.  Without them I believe the spitfire would have found itself in the same situation as the Zeke in the Pacific.  

Regarding the total drag, there is not much difference between these planes; at about same output the speed of the planes is about same.

There is very large gap in relation to the one you are trying to claim at the wingtips!

Flat Plate comparison:

FW-190 - 5.22

Spitfire - 5.4

And that difference quadruples in relationship to velocity.

All in all, while I appreciate your calculator work it's not factual.  I don't think there is any intent to deceive, you just got the wrong inputs on some things.  It shows nothing other than the Spitfire had efficient wingtips.  I said that 3 post's down, bro.    

Crumpp

[gripen]

Originally posted by Crumpp


Wing aspect ratio for the FW-190A8 is 6.0 not 5.96.  This will figure out the CL at different angles of attack.

Ah, I had a typo in the spread sheet; 18,5m2 instead 18,3m2 so the aspect ratio of the Fw 190 is actually 6,02. Lower wing area also affects lift coefficient which actually increases induced drag of the Fw 190. So the corrected results for the Fw 190 are:

200km/h Cl=1,088 Cdi=0,0695
600km/h Cl=0,121 Cdi=0,000858

Originally posted by Crumpp

However If you compare the wing roots, you find the opposite is true. Increase the angle of attack and the Spitfire has large disadvantage in drag.

Nonsense, the Spitfire had lower induced drag at any reachable angle of attack, here is numbers for 3g at 300km/h and 600Km/h.

Spitfire IX
300km/h Cl=1,043 Cdi=0,0686
600km/h Cl=0,261 Cdi=0,00429

Fw 190A-5
300km/h Cl=1,451 Cdi=0,124
600km/h Cl=0,363 Cdi=0,00772

Originally posted by Crumpp

Again you seem to think induced drag and basic drag are the same thing.

I wonder where I have said so; I have merely pointed out that the Spitfire had lower induced drag than the Fw 190 and that there can't be big differences in the total drag.

Originally posted by Crumpp

There is very large gap in relation to the one you are trying to claim at the wingtips!

Nonsense, the induced drag affects all over wing area, from NASA site:

"Downwash causes a local induced angle of attack with additional induced drag on a finite wing."

Originally posted by Crumpp
Flat Plate comparison:

FW-190 - 5.22

Spitfire - 5.4

And that difference quadruples in relationship to velocity.[/B]

Why the Spitfire and Fw 190 are about as fast at about same output if the Spitfire produced much more drag. If your theory is true then the Fw 190 had extremely unefficient propeller.

Originally posted by Crumpp

All in all, while I appreciate your calculator work it's not factual.  I don't think there is any intent to deceive, you just got the wrong inputs on some things.  It shows nothing other than the Spitfire had efficient wingtips.  I said that 3 post's down, bro.    

The calculation shows two things:

1. The induced drag decreases when the speed increases. This is exactly opposite you claimed above.

2. The Spitfire had lower induced drag than the Fw 190. The induced drag has nothing to do with differences in zoom climb and dive acceleration. This is exactly opposite you claimed above.

In addition speed comparison show that there can't be big differences in the total drag.

gripen

[Crumpp]

In fact,

Let just nip this in the bud and break it down to Barney Level.

In Aerodynamics what is the Force diametrically opposed to Thrust?

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

DRAG opposes Thrust, correct?

In going from the Spitfire Mk IX Merlin 61 to the Spitfire Mk IX Merlin 66 we see NO appreciable wieght gain.

We do see an appreciable gain in available Horsepower.  Around 485 hp.  Some want to claim 700 hp however I believe that is a little steep.

Merlin 61 (+18) @ 3000 rpm Full throttle hieght = 1565hp

Merlin 66 (+25) @3000rpm Full throttle height = 2050hp

Top Speed - 411 mph
FW-190A8 - 408 mph

A difference that is hardly noticable in the air.  

Same Airframe and a 485 hp increase only yields an average of 30 mph speed increase??

And that top speed equals the FW-190A8 but not at all altitudes but is slower than the FW-190A5??

You still want to claim the spitfire had less drag and could zoom on equal footing with a 190?

In the Entire FW-190A jagd-einsatz we see less weight gain than the going from the Spit Mk V to the Spit Mk IX.  This comes with a similar horsepower increase.

Spitfire mkVb - 6525lbs Take off wt (2 x 20mm, 4 x .303)
WL - 28lbs/sq. ft
Merlin 45 - 1470Hp@3000 rpm Full throttle height (one we have in AH I think)

Spitfire Mk IX - 7,480lbs Take off wt
WL - 30.9lbs/sq. ft
Merlin 66 (+25) - 2050 hp @ 3000 rpm Full throttle height

Horsepower increase - 580hp.
Weight increase - 955lbs


190A3 - 8770lbs Take off wt
WL - 43lbs/sq. ft

FW190A5 - 9052lbs Take off wt
WL - 44lbs/sq. ft

FW-190A8 - 9418 lbs Take off wt
WL - 46lbs/sq. ft

Total Weight gain - 648lbs
WL Increase - 3 lbs/sq. ft

Usable Hp Increase - 350hp to 450hp depending on the source.  Top Horsepower equals the Spit Mk IX just as the Top Horsepower of the Merlin 61 equalled the FW-190A3.  The FW-190 gained less weight and almost as much Horsepower.

Bottom line - The "weight gain" killed performance theory is a crock unless the Spitfire operates under a different set of physics.
Any claims of it NOT having lots of drag are just plain fantasy.

I will be glad to mail you the docs I am using for the 190 weight's.  Give me your email.

Crumpp

[Crumpp]

Nobody is claiming the Spitfire couldn't zoom well because of it's INDUCED drag Gripen.

It couldn't zoom well because of its Drag period.  

Are you trying to say that is suddenly gains thrust when the Spit points it's nose up?

Are you saying it has NO induced drag?  The induced drag, no matter how small, only ADDS to the total drag already present, which is appreciably higher than the 190's.

Without the inertia gained in the weight increase of the Spit XIV the Spit IX was unable to follow a 190 in the zoom.  Especially when the FW-190A8 was an improvement in zoom climb and dive accelleration.  Two key components of an energy dogfighters performance.

It is just like Robert Johnson's encounter with a Spitfire in 1943 while flying a P47.  The P47 was clearly outmatched in turn performance and sustained climb.  Johnson however could leave the spit behind in the zoom as long as he did not hold the climb when he slowed down.  Using a superior dive accelleration to gain speed followed by a zoom climb to gain height, he was able to come barrelling down on the Spits six and get a gun solution.  Exactly the same manner in which 190's fought.  Infact read the tactical trials, the 190 outzooms the P47.  A FW-190 @ 1.35ata can outzoom a P47.  You can read the tactical trials here:

http://prodocs.netfirms.com/

Crumpp

[gripen]

Originally posted by Crumpp

We do see an appreciable gain in available Horsepower.  Around 485 hp.  Some want to claim 700 hp however I believe that is a little steep.

Merlin 61 (+18) @ 3000 rpm Full throttle hieght = 1565hp

Merlin 66 (+25) @3000rpm Full throttle height = 2050hp

Top Speed - 411 mph
FW-190A8 - 408 mph

A difference that is hardly noticable in the air.  

Same Airframe and a 485 hp increase only yields an average of 30 mph speed increase??

The FTH of the Merlin 66 at MS gear and at +25lbs was a bit less than 3k so lets compare speeds around this altitude:

JL165 Merlin 66 (+25) 364mph
JF275 Merlin 66 (+25) 374mph
BF274 Merlin 66 (+15) 327mph (aproximated, results end to 6k)
Average for Merlin 66 (+18) 350mph (from MA648 graph)

In practice this means that the Spitfire gained around 60-70km/h with about 500hp increase (+25) and around 40km/h with 150hp (+18) increase. Note that there was no +18lbs Merlin 61.

As for comparison the Fw 190A-5 gained about 50km/h (550-600km/h) with about 230ps (from 1,32 and 2400rpm to 1,42ata and 2700rpm) increase at about same altitude and Fw 190A-8 gained about 20km/h (560->580km/h) from 1,42ata to 1,58/1,65ata (from your source page). These is no practical difference between planes if we compare speed gains at given output increase nor big differences in the speed.

Originally posted by Crumpp

Bottom line - The "weight gain" killed performance theory is a crock unless the Spitfire operates under a different set of physics.
Any claims of it NOT having lots of drag are just plain fantasy.

Someone is creating plain fantasy here and it's not me. The evidence is above.

Originally posted by Crumpp


Nobody is claiming the Spitfire couldn't zoom well because of it's INDUCED drag Gripen.

You above:

"Now this same wing gave it excellent low speed handling but the lift it generated worked against it at high speed. Induced drag has an inverse relationship to Aspect ratio. The lower the ratio the higher the drag."

"The wing aspect ratio of the 190 is better.

Spitfire - 5.61

FW-190A3 - 6.01


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

It also explains why the 190 had a much better zoom climb."

Originally posted by Crumpp

Are you saying it has NO induced drag? The induced drag, no matter how small, only ADDS to the total drag already present, which is appreciably higher than the 190's.

The induced drag calcultions are above, the Spitfire had lower induced drag than the Fw 190. There seems to be no big differences in the total drag even according to your own sources.

gripen

[Crumpp]

As for comparison the Fw 190A-5 gained about 50km/h (550-600km/h) with about 230ps (from 1,32 and 2400rpm to 1,42ata and 2700rpm) increase at about same altitude and Fw 190A-8 gained about 20km/h (560->580km/h) from 1,42ata to 1,58/1,65ata (from your source page). These is no practical difference between planes if we compare speed gains at given output increase nor big differences in the speed.

No the speed didn't change that much however the weight did increase.  What we see in the FW-190 is an appropriate increase in power along with it.  It already had a speed advantage over it's main rival.  Same power to weight with more weight = better zoom climb and better dive accelleration. This is easily verifiable by examining the Manifold restrictions, weight gain, and the Luftwaffe's "derating" of the BMW-801D2 in 1942.
You forget that the Luftwaffe had an enemy test flight too.

In practice this means that the Spitfire gained around 60-70km/h with about 500hp increase (+25) and around 40km/h with 150hp (+18) increase. Note that there was no +18lbs Merlin 61.

Your right I meant Merlin 61 (+15), typo.  So It increased
 60Km = 37 miles per hour to 70 km = 43mph for a 500 hp increase and recieved an additional 40 km = 24mph for adding another 150hp.

Total gain; 750 hp = 61mph - 67mph

1. 750 Hp in 1939 was the total power of many of the worlds frontline fighters.  The Spitfire added a huge amount of additional power for tiny gains in speed.  Why?  It had to fight to overcome the great lift it's wing provided.  You so badly want to have you cake and eat it too.  Doesn't work that way.  The Spitfire was one of the worlds great fighters

Now lets look at verifiable facts on the Spitfire:

Merlin 61

Maximum true air speed in M.S. supercharger  380 1/2 m.p.h. at 15,400 ft.  
Maximum true air speed in F.S. supercharger  403 m.p.h. at 27,400 ft.

http://www.fourthfightergroup.com/eagles/spit9.html


For the Merlin 66 (+25)

Maximum true air speed in M.S. gear 364 mph at 2,800 feet  
Maximum true air speed in F.S. gear 389 mph at 13,800 feet  
Estimated increase in speed below full throttle heights due to
increase in boost from +18 to +25 lb/sq.in. 30 mph.  

 That's the 500 hp gain right?? No gain in weight either??

http://www.fourthfightergroup.com/eagles/jl165.html

Here it does a little better in this one When the testing was completed in Feburary of 1944:

http://www.fourthfightergroup.com/eagles/jl165.html

Max. speed at F.T. height (9,400 ft.) in M.S. gear = 379 mph  
Max. speed at F.T. height (21,000 ft.) in F.S. gear = 411 mph  

Lets say it is Early to Mid 1944, when (+25) was approved, and we have the new SU pump tested in Feburary '44 then we can add 30 mph on average (according to the RAF) and bump the top speed up too 441 mph in F.S. gear.  

So for 750 hp gain (which you claim) we see a top speed increase from the Merlin 61 to the Merlin 66 (+25) OF:

Merlin 61 - 403 mph
Merlin 66 -  441 mph (based on speculation since we have no speed test or hard data at these conditions)
Merlin 66(+25) - 389mph (the one we do have hard data on.  It did gain 9 mph over the Merlin 61 at the same height.)


38 mph gain for 750hp input.

Thrust is opposed by drag right??

Crumpp

[Crumpp]

By your calculations the difference in induced drag is:

Spitfire IX
300km/h Cl=1,043 Cdi=0,0686
600km/h Cl=0,261 Cdi=0,00429

Fw 190A-5
300km/h Cl=1,451 Cdi=0,124
600km/h Cl=0,363 Cdi=0,00772


Which BTW your numbers in now way match the calculator from the US Naval Academy Post Graduate.
I would apreciate it if you would list all the values you are using.

E factor etc...

Since they don't match and drag calculations can very easily be manipulated I think the huge thrust gain for very little speed gain pretty much illustrates the point.

Crumpp