Fw-190 Dora-9 vs P-51D Mustang

[FLYBOYJ]

I would like however to mention, your charts are beautifully done, that you are applying your data incorrectly. For example, the turn charts although at 1st pass they looked good, and the planes seem able by math to do what your tables suggest, but at 340 MPH, you'll rip the wings off these birds, even if empty, as you have exceeded the airframe's stress ratings.

Nice information guys and nice to see you posting again JJ. When you say his charts are wrong are you speaking in terms of True Air Speed vs Indicated Air Speed? For example in the portions of the P-51 -1 JJ posted it shows Indicated Airspeed limiatations at altitude, have you done an example to see what the "True Air Speed" would be at sat 25,000 feet with the outside air temperature at -20F? It could be done with one of these....

 

[lesofprimus]

Great info right there guys, good one Jon...

 

[pbfoot]

when all these numbers for airspeed are cited are they all using the same criteria like humidity and temperature on the charts there is no reference given to these important variables

 

[paul.kachurak]

Jon,

Thanks for the information.

I use true airspeed for all my calculations not indicated airspeed.

I guess I don't understand why you say I will exceed the aircraft limitations when I purposefully limited the max g to 6 not to represent the limits of the aircraft but rather the limits of a human without a g suit.

Here is what I used for the Fw190D-9
gross weight = 9147 lb (68% fuel, full ammo)
CLMAX = 1.58
wing area = 197 sq ft

I don't see in your graphs what the weight, wing area, or CLMAX is. You do need all those things. Further I don't know what altitude you are looking at because all that will change with altitude.

But let me run through and example...

First to let you know my background I am an aerospace engineer who works for the USN. I have been involved with aircraft mass properties for about 15 years. I don't do aero performance but it is my hobby, too.

So using the above data for the D-9 and using sea level (soory for not knowing how to du greek symbol on a forum like this)
air density (rho) r = 0.002376 slugs/ft^3

We know that Lift (L) = load factor (n) * weight (W)

And we know that L = 0.5 * r * V^2 * S * CL so we have all we need to solve for speed in ft/s for any load factor at the CL we want to use CLMAX. This will give us for the peak n the instantaneous load factor from which we can find instantaneous turn rate, which is what your chart shows.

So
n = 6
W = 9147
S = 197
r = 0.002376
CLMAX = 1.58

6 * 9147 = 0.5 * 0.002376 * V^2 * 197 * 1.58

Solving for V we get 385.25 ft/s = 262.67 mph = 422.7 kph

In the plot I show at 5000m. Here's the numbers I used for that:
n = 6
W = 9147
r = 0.001428 (std atmosphere air density at 5000m)
S = 197
CLMAX = 1.58

Solving for V = 496.9 ft/s = 338.8 mph = 545.2 kph

I repeated this same process for other altitudes I never went over 6 gs for either the Fw190D-9 or the P-51D. If you'd like to see my Excel file I would be more than willing to send it to you. It's not so user friendly. No two engineers think a like.

Those plots look a lot like the ones that the CFS2 1% group make. Is that where you got them? I have those, too. In fact I'm looking at them right now and I can't tell what weight they use. Take a look in the upper left hand corner of the Turn Performance spreadsheet and you'll see CLMAX of 1.58. In that CFFS2 1% workbook you'll see that those guys also calculate the airplane CLMAX from the airfoil CLMAX. Very cool stuff and I was glad to see their calculations match the FW number of 1.58. I have the P-51D-30 CFS2 1% stuff too and they calculate a CLMAX of 1.48.

CLMAX is the maximum lift coefficient that an airplane or airfoil can produce before the wing stalls and the lift drops off. It is so hard to find a good definition of what the lift coefficient is. I understand what it is but giving a good definition is hard. None of the texts I have from college really give a good layman's definition. Lift coefficient CL is most simply put it is the non-dimensional (meaning it has no units like feet or meters) measure of lift capability. CLMAX is the upper bound on this capability. You get different CLs at different angles of attack given a constant speed. Make any sense? If you are really interested I recommend picking up some texts like "Theory of Wing Sections" by Abbott and vonDoenhoff, "Aerodynamics for Engineering Student" by Houghton and Carruthers, or "Aerodynamics for Engineers" by Bertin and Smith. All will put you to sleep in 3 minutes. But that's what I have from school.

Oh here's one "Aerodynamics for Naval Aviators". I'll bet they make it so simple even a nugget pilot can understand .

"Lift coefficient" would be the ratio between the lift pressure and dynamic pressure;...The use of the coefficient form of an aerodynamic force is necessary since the force coefficient is:
(1) and index of the aerodynamic force independent of area, density, and velocity. It is derived from the relative pressure and velocity distribution.
(2) Influenced only by the shape of the surface and angle of attack since these factors determine the pressure distruibution
(3) an Index which allows evaluation of the effects of compressibility and viscosity. Since the area, density, and velocity are opbviated by the coeffcient form, compressibility and viscosity effects can be separated for study."

CLMAX occurs at the minimum speed for a given lift requirement.

 

[paul.kachurak]

once I receive the Jumo stuff I will delete my thread.

if you would please.... ?

many thanks

Erich ~[/quote]

Erich,

I will-do tonight when I get home.

 

[paul.kachurak]

intersting just checking through data on the engines of the Ju 88G-6. not bad for an old hunk of bolts. 2 Jumo 213E's with 1,880 h.p. up to 2,250 h.p. rating when needed...............

E ~

I agree. I have a Jumo213E1 power plot, too. But the Jumo213E1 was not installed in the Fw190D-9. It was installed into the Ta-152.

One must remember that Kurt Tank considered the D-9 as an interim solution until he could get his real high altitude plane developed. If you don't have it I recommend "Focke-Wulf Fw 190 Long Nose" by Dietmar Hermann available at Schiffer Books http://www.schifferbooks.com/newschiffer/book_template.php?isbn=0764318764

It is chock full of great development history. The seemingly painful situations that the RLM put Focke Wulf through. Good pilot accounts. IMO a great book for the Longnose 190 enthusiast.

 

[paul.kachurak]

Aww hell I am 99.99% sure I got these off of the internet so I'll post them. The first is the drag data. Also on there is camax aka CLMAX. You will also see about 2/3 of the way down under the D-9 column and on the Nstart row that with MW50 the power is 2100 PS. I have a power curves for a Jumo213A that show 2100 PS that I cannot post that IMO confirm this power. The second has speeds and climbs. This second matches well with the 11 Mar 45 sheets I have which I also cannot post.

 

[Erich]

Paul yes I have the Dietmar book, nice tech book, not the best for personal accts in my opinion. I was fortunate to chat with Will Reschke, quite an outstanding pilot and gentleman. Quite the stories too. E.E was suppose to have a book out just on JG 301 with unpublished info on the Tank but it appears it will be at leat the Tank info in EE's book on the Dora that I have placed in an earlier thread in this section ............

can you post the power plot on the Jumo E maybe in a new thread as I do not want this interesting thread to go off topic ?

thanks in advacne for the information via e-mail

E ~

 

[syscom3]

It would be great if the charts were translated to english using US weights and speeds.

 

[KraziKanuK]

1kg = 2.2lb
100kph = 61mph

 

[paul.kachurak]

Syscom3,

Yes it would be nice but it is also nice to see it in German because IMO it enhances it's authenticity. Do you have any questions on those two? I've used this site http://dict.leo.org/?lang=en&lp=ende&search= to translate a lot of it and the rest I've figured out what it is on my own. German is a tricky language.

To convert from kilograms to pounds mulitply kgs by 2.204623
To convert from meters to feet multiply meters by 3.28084
To convert from square meters to square feet well multiply by the square of 3.28084
To convert from kilometers per hour to miles per hour multiply kph by 0.6213712

I can tell you this from my school days it is a heck of a lot easier working in metric than in US units.

 

[Lunatic]

I've posted the P-51 handbook data which clearly shows a 395 mph and an over 400 mph cruise.

Is that with or without dts?

As you can see, the P-51 was capable of a 425 mph cruise with a range on internal fuel (as specified) of 850 miles.

What is dts?

=S=

Lunatic

 

[FLYBOYJ]

As you can see, the P-51 was capable of a 425 mph cruise with a range on internal fuel (as specified) of 850 miles.


=S=

Lunatic

Great chart, but are you saying that the -51 "cruises" at this setting (at 30,000 feet)? The way I read that chat it's showing Max. Continous, (97GPH) 2700 RPM. "Cruise" or an econmical setting would be on the far right and a lot lower, and the airspeed is TAS not indicated. If converted to indicated, (depending on temp density altitude) it would be a lot lower....

 

[KraziKanuK]

The Spit has a TAS of 314mph @ 20k' which is 235mph IAS turning 2650rpm.

If my math is correct, then the P-51 had a IAS of 318mph at the same altitude, some 72mph slower than the shown TAS.

 

[Lunatic]

I've posted the P-51 handbook data which clearly shows a 395 mph and an over 400 mph cruise.

Is that with or without dts?

Cruise speeds are always dependant on range issues The P-51 cruised at about 260mph for max endurance/reasonable speed and according to a P-51 pilot who flew out of England durring the war thats what they flew at. However a pilot that flew with the checkertails out of Italy said that they frequently flew at 350/360mph cruise but NEVER faster than that unless they were in attack mode "It used to much fuel" Quote and italics are his.

My TO-1 states Max endurance at 140mph CAS
Max range Wing racks only 35,000ft 66gph 367mph but at 10,000ft its 261mph and 42gph. Our checkertail friend stated they used 55/60 gph to define/limit/optimize their cruise speeds.

My TO-1 Mustang handbook states Full Throttle (military) for a P-51D is 424mph. All stats and tests I've seen rate the P-51 D at 420s in military or 1,590hp and 437mph at 1,650hp in WEP. The P-51B/C was about 3 mph faster. The 1 test I've seen with a P-51 in the 450mph range was 'cooked' The aircraft was well over 1,000 lbs lighter than normal test weight and probably prepared in other ways because this was a max possable test not a comparison test.

wmaxt

That's BS. I have the test report and the P-51B tested, AAF serial # 37050, was at 9423 lbs takeoff weight - fully loaded clean condition. The only change from production on the plane was a reworking of the radio antenna which was a standard field change usually applied before the planes were delivered to combat units. Maximum speed, 351 mph TAS, was determined at 3000 rpm and 67" of manifold pressure at ~29000 feet.

And if anything the USN report is biased against the P-51B and in favor of the F4U-1 and -1a used in the test.

 

[Lunatic]

As you can see, the P-51 was capable of a 425 mph cruise with a range on internal fuel (as specified) of 850 miles.


=S=

Lunatic

Great chart, but are you saying that the -51 "cruises" at this setting (at 30,000 feet)? The way I read that chat it's showing Max. Continous, (97GPH) 2700 RPM. "Cruise" or an econmical setting would be on the far right and a lot lower, and the airspeed is TAS not indicated. If converted to indicated, (depending on temp density altitude) it would be a lot lower....

The chart is right out of the P-51D pilot handbook. The brownish highlighting with rounded boxes is the handbook example, which shows a 325 mph cruise at 10,000 feet yeilds an 1100 mile range, after climbout (which is covered on the previous page). The left column shows the maxium speed continous cruise possible, and each colum to the right shows a progressively longer range cruise at a lower power rating.

Notice that at 30,000 feet at 2450 rpm and full throttle hight in the run condition the P-51 can managed 1220 miles after climbout.

Of course indicated air speed would be lower at altitude, but that is true for every plane equally right? Top speed and cruise speed figures are almost always given in TAS.

=S=

Lunatic

 

[FLYBOYJ]

The Spit has a TAS of 314mph @ 20k' which is 235mph IAS turning 2650rpm.

If my math is correct, then the P-51 had a IAS of 318mph at the same altitude, some 72mph slower than the shown TAS.

That sounds about right at standard temperature/ pressure (59F at seal level, 29.92).

 

[wmaxt]

[quote="Lunatic]
That's BS. I have the test report and the P-51B tested, AAF serial # 37050, was at 9423 lbs takeoff weight - fully loaded clean condition. The only change from production on the plane was a reworking of the radio antenna which was a standard field change usually applied before the planes were delivered to combat units. Maximum speed, 351 mph TAS, was determined at 3000 rpm and 67" of manifold pressure at ~29000 feet.

And if anything the USN report is biased against the P-51B and in favor of the F4U-1 and -1a used in the test.[/quote]

No BS (which I resent) the data is right out of the Pilots Handbook for the P-51D 1947 edition.

Then I haven't seen the report you are refering to. The report I'm refering to had the P-51 at a weight listed below 8,000lbs and was not being compared to anything. I have looked but not found any tests or specs on the P-51 that indicate otherwise - that does not mean they don't exist - I haven't found or seen them. The other thing is that specs on the P-51 are very consistent even from Mustang advocates, if the P-51 was normaly faster (and 10/12mph is significant) than reported surely we would be hearing about it?

Flyboy, is also correct, Max Continous, is not cruise and according to the pilots I contacted they flew cruise at 55/60gal/hr 250/260IAS ~360TAS (I think thats high for TAS) @ ~25,000ft, and he made a point of stating, in italics, that anything faster than that used to much fuel for anything but actual combat. Three-sixty is substantial and better than almost every one else. I also posted the max range numbers which lists 367mph @ 35,000ft 66gph and 261mph @ 10,000ft both numbers TAS. The Pilot I contacted that flew out of Britian flew 250mph (I assume IAS) on missions over Germany including sweeps.

I repeat, I've only shown or commented on data I have, with no additions, modifications or adjustments.

wmaxt

 

[Udet]

Mr. Lunatic:

I´ll get back to you later on this, sorry.

 

[FLYBOYJ]

The chart is right out of the P-51D pilot handbook. The brownish highlighting with rounded boxes is the handbook example, which shows a 325 mph cruise at 10,000 feet yeilds an 1100 mile range, after climbout (which is covered on the previous page). The left column shows the maxium speed continous cruise possible, and each colum to the right shows a progressively longer range cruise at a lower power rating.

Notice that at 30,000 feet at 2450 rpm and full throttle hight in the run condition the P-51 can managed 1220 miles after climbout.

Correct! I thought you were suggesting that the chart on the lower left (where you got the 425 mph) was a cruise chart. Big difference in fuel flow!!!

Of course indicated air speed would be lower at altitude, but that is true for every plane equally right? Top speed and cruise speed figures are almost always given in TAS.
Lunatic

Actually indicated airspeed would match closer to TAS at lower altitudes if air temp and pressure a standard (29.92, 15C).

here's some rough examples.
Pressure Altitude S/L OAT +15c IAS 300MPH TAS 300
Pressure Altitude 5000' OAT 0c IAS 300MPH TAS 319
Pressure Altitude 10000 OAT -20C IAS 300MPH TAS 332
Pressure Altitude 20000 OAT -40C IAS 300MPH TAS 395
Pressure Altitude 30000 OAT -60C IAS 300MPH TAS 463