Draining E in turns

[gripen]

English is not my native language. What is the SWAG test?

gripen

[Crumpp]

Quick calculations to confirm data.  I am running into lots of conflicting data on the FW-190.  Need a good way to determine if it is "good" or "bad".  I want to dispel myths, not perpetuate them.

Crumpp

[gripen]

Grab Zigrat's spreadsheet from F4UDOA's page. It's in english units and it seems to work fine. If compared to my spreadsheet, it's far more sophisticated. In my calculation I check propeller efficiency manually as well as exhaust thrust.

gripen

[Crumpp]

Can't find a link F4UDOA's page.  If you got one I would appreciate it.

Crumpp

[Nashwan]

http://mywebpages.comcast.net/markw4/

There's lots of interesting stuff on there.

[Crumpp]

OK got it and been playing with it.

Now how do I know I have "good" data in it?

What are the checks.

Crumpp

[Crumpp]

Thanks BTW Nashwan for posting your calculator.

Crumpp

[Badboy]

Originally posted by hitech
If you would try this aproch I belive the following would happen.

1. You would have quite a few people willing to talk about the topic's you love. Because guess what, they don't want to prove themselvs correct. They want to do 2 things.

1. Give their knowledge and excitment to others.
2. Pick up on new knowledge and thoughts that they hadn't seen or thought of  before.


If you would try this aproch I belive you would increase your knowledge at a faster rate. You would also have a lot more fun.


Just some friendly advise for what it's worth.

HiTech

Well said HT.

I teach this stuff for a living, and as much as I want to help, I have begun to avoid threads like this one. The reason is that one can easily spend a lot of time trying to help guys who don't really want to be helped at all. It seems that some folk want to learn and share ideas, while others just want to be right, even if they aren't  ;-)

Badboy

[Crumpp]

It seems that some folk want to learn and share ideas

How about helpin out then.

Now how do I know I have "good" data in it?

What are the checks.
 

Crumpp

[Angus]

Well, there is a point there.
A slightly provokative thread usually produces more data

[Crumpp]

FW-190A8 NM at 10 K = 1.2926E+10
FW-190A8 NM at 20K = 25852821750

Spitfire Mk IX Merlin 66 NM at 10K = 1.0157E+10
Spitfire Mk IX Merlin 66 NM at 20K = 20313000000

Spitfire Mk IX Merlin 66
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) - 13800
Maximum speed (at test alt.- mph) - 389
Engine Horsepower (bhp at test alt) - 1650
Stall speed (mph, at test alt) - 90
Horsepower rating is at  +19.5 max boost @ 3000 rpm at 13,800ft AGL.

FW-190A8 BMW-801D2
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45

Step B - performance #s at a known altitude
    
    
Altitude (feet) - 17224
Maximum speed (at test alt.- mph) - 408
Engine Horsepower (bhp at test alt) - 1680
Stall speed (mph, at test alt) - 110
Horsepower rating is at 1.58ata/1.65ata @ 2700U/min


Comparison under same conditions @ 300mph IAS.

                           
Spitfire Mk IX  CL=0.196312  D(p)=706.7709 D(i)=97.17467           CD(tot)=0.02132  Drag (tot)=803.94557


FW-190A8  CL= 0.343145  D(p)=595.7239  D(i)=197.875  
CD(tot)=0.028915   Drag (tot)=793.59888

                                 thrust (lb)         T-D
Spitfire Mk IX           1544.397          740.451
FW-190A8                1550.793         757.1939


Conclusions -

Under 1G the FW-190A8 and the Merlin 66 Spitfire are very similar in total drag.  The faster the speed the more the FW 190 moves to advantage.  The slower the speed the more the Spitfire moves to advantage.

The FW-190A8 always has much more inertia and potential energy to convert to Altitude or Speed.  It also has less braking forces per mass applied to it.

David Lednicers data reflects this conclusion.  The FW-190 has less parasitic drag than the Spitfire but produces more induced drag.

The data used for each was:

Spitfire:

Perfomance numbers:

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

http://www.fourthfightergroup.com/eagles/jl165speed.gif

Dimensional data is out of:

"British Warplanes of WWII" Edited by Daniel J. March.

Horsepower data was extrapolated using:

http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg

Focke-Wulf 190A8

Performance numbers:

http://www.terra.es/personal2/matias.s/fw190-1.jpg

Dimensional data is out of:

Flugzeug-Handbuch D(Luft) 2190 A-7 bis A-9 March 1944.

Horsepower data for the BMW-801D2 @ 1.65ata comes from a mechanical engineering anaylsis of the BMW-801D2 motor performance based on the following NACA Bench test analysis:

http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg

I will gladly share the analysis results with anyone.

Special thanks to Angus and Nashwan.

Crumpp

[gripen]

Originally posted by Crumpp
FW-190A8 NM at 10 K = 1.2926E+10
FW-190A8 NM at 20K = 25852821750

Spitfire Mk IX Merlin 66 NM at 10K = 1.0157E+10
Spitfire Mk IX Merlin 66 NM at 20K = 20313000000

Hm... I quess this is an energy calculation, are these values for potential energy or is there some kinetic energy within? If there is kinetic energy, what's the speed?

Originally posted by Crumpp
Comparison under same conditions @ 300mph IAS.

What's the comparison altitude?

I wonder why IAS values.

Originally posted by Crumpp
The data used for each was:

Spitfire:

Perfomance numbers:

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

Why the JL165, it performed way below average?

Originally posted by Crumpp
Horsepower data was extrapolated using:

http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg

The problem with that chart is that it mix together the engines with different FS gear and your comparison seems to be at FS gear. As an example:

Merlin 66 FS gear ratio 7,06
V-1650-7 FS gear ratio 7,35

In addition that chart is far too unaccurate for analysis.

Originally posted by Crumpp
Horsepower data for the BMW-801D2 @ 1.65ata comes from a mechanical engineering anaylsis of the BMW-801D2 motor performance based on the following NACA Bench test analysis:

http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg

AFAIK That chart is not from the NACA.

gripen

[hitech]

Crumpp: Not sure if you know or not. But when computing drag & lift with normal equations you should be using TAS not IAS. The same goes for computing energy.

HiTech

[Angus]

Hey Crumpp:
"Conclusions -

Under 1G the FW-190A8 and the Merlin 66 Spitfire are very similar in total drag. The faster the speed the more the FW 190 moves to advantage. The slower the speed the more the Spitfire moves to advantage.

The FW-190A8 always has much more inertia and potential energy to convert to Altitude or Speed. It also has less braking forces per mass applied to it.

David Lednicers data reflects this conclusion. The FW-190 has less parasitic drag than the Spitfire but produces more induced drag. "

I'm no expert, but as the Spitfire wing presumably produces more lift, it should also produce more induced drag.
Now as far as I know, induced drag is inevitable as a function of what is being lifted, - (LIFT induced drag is it's full name), it still has it's double sides of the coin.
A high lifting wing will reduce A of A, hence also drag.
A lower lifting wing will have to have higher A of A at low speeds in order to fly. However, when speed is ample, lift creation is almost a liability.

About this point here:

"The FW-190A8 always has much more inertia and potential energy to convert to Altitude or Speed."

I have to disagree, regarding altitude.
And yet not......
This is not just that simple....
The 190 has a higher stalling speed than the Spitty, especially under high pitched angles. (Chord thingie )
So, it's not an ALWAYS, but MOST OFTEN subject.
It should at all times have the more energy, however, not always the possibility to convert it into altitude, due to stalling dynamics.

[Crumpp]

Comparison under same conditions @ 300mph IAS.

Thanks Hitech, It's a typo - all comparisons are at 300mph TAS.

I recalculated the figures for 4500 ft. ASL because I do not think the table is adjusting the speeds for altitude.  Here are the results.  

The FW-190 is at 1.42ata @ 2700U/min as my horsepower data is much more accurate for 4500 feet.  All data is calculated at 356mph the max level speed of the FW-190A8 at that altitude and power setting.  This forms the base information at which the performance at lower speeds can be assessed.

FW-190A8
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45
   
Step B - performance #s at a known altitude
    
    
Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110

speed (mph TAS) @ 4500 feet ASL  
300

CL
0.229178

D(p)        
952.5006

D(i)    
132.1558

CL^2  
0.052523

CD(tot)  
0.026394

Drag (tot)
1084.6564

thrust (lb)
1667.946

excess power (bhp)
583.2895

P.E.
0.78153

Spitfire Mk IX Merlin 66 (+25) -  This data represents full throttle height for the Spitfire and an easy point to calculate from.  Since my data is much more complete for the FW-190 it is easier to identify the Spitfire's knowns and then establish the FW-190's performance at the same altitude.  Initial data was calculated under the following known conditions:

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) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90


speed (mph TAS) @ 4500 feet ASL
300

CL
0.146573

D(p)
1229.828

D(i)
72.55357

CL^2
0.021484

CD(tot)
0.025796

Drag (tot)
1302.3818

thrust (lb)
1976.468

excess power (bhp)
674.0858

P.E.
0.78153

Data all came from the same sources.

The problem with that chart is that it mix together the engines with different FS gear and your comparison seems to be at FS gear. As an example:

It's the best data I have.  If you have better data I would love to get a copy of it and will recalculate the numbers.

Why the JL165, it performed way below average?

It's the best and most complete data I have on the Spitfire Merlin 66 (+25).  The S.U. pump data is with a Merlin 66 (+18) and only "estimates" the speed increase.  Additionally the speed increase is an average and would not hold true for all altitudes.  This can be seen in the increase at full throttle height of a Merlin 66 (+18) is not nearly as large as the "average" with the fuel pump.  
Please share your data and I will recalculate.  I will share my information on the FW-190 as well.

Not all of it though, gotta save some for the book!

AFAIK That chart is not from the NACA.

 Your right it is from a 1942 bench test conducted by BMW.  The report number is on the graph.

Crumpp