New D-9 FM since 2.0?

I mean, all this graphs and video, they do not mention P-51 mass and FW190 mass during comparison tests.

For example lets take Yo-Yo graph, I cant understand if they are measured for P-51, FW190 and Bf109 with equal mass, or with 100% fuel and 100% ammo, or 10% fuel and 0% ammo. I suppose we need some mass to refer to make a comparison of turn rates.

This is true, yes, and very important. I asked Crumpp & Hummingbird to list theirs, and we really need to know what mass the aircraft were at in Yo-Yo's graph, as well. I would assume that it was nearly full fuel & ammo, but that needs confirmation.

YoYo's graph also shows that Bf109K4 is able to complete its turn at 550kph faster than P-51 and Fw190, I presume that simulation didn't take into account stick forces for the 109. I don't think that graph is very accurate. Even YoYo stated that it was just to show that estimates for both Foke Wulf and the Mustang are very close. Am I correct?

The D9 can easily turn into the P-51's turn at high speeds. But won't be able to turn with it at prolonged turn fights. Thats how it was in all other simulations in the past and I do not see why it is now such a shocker for so many.

Not always shooting down 4 mustangs but say taking down two and evading getting my arse shot down, against say two set to high and two set to good. Although there has been a couple of occasions where I got 4 and didn't run out of ammo. But as I say in 2.0 despite desperately trying to avoid a turning fight I'm struggling.

I see, against AI, not human. I think there have been some improvement with AI performance in the latest versions.

Happy landings,

Talisman

And what about mass? :)

Crumpp and I were both flying with 100% fuel in our tests.

I had left a P-51 in there with 68% fuel incase we wanted to test that, but the results at 100% gave us no reason to try it.

Can we expect the Zeke-51 to be fixed sooner or later?

Can we expect the Zeke-51 to be fixed sooner or later?

Can you tell what is wrong with the P51D? Facts please. Not just "I feel". Also, it is a Fw190 thread.

You like it that way Solty? Stop your BS. Everybody knows something changed about it. I got a mission where I fight two of them. in 1.5.0 I could down both of them. Now I can' t even get one. The AI not taking damages into account doesn' t help, either.

You like it that way Solty?

What way?

Turning way better than it should... Did you read this thread?

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Yo Yo says:

 

I think, the math you use has a lot of simplification, and it is due to limited number of input parameters. It has its right to be implemented, in many cases it can predict performance with engineering accuracy (+-10%, sometimes less).

The math is standard subsonic incompressible flow theory correctly applied.

It is as simple and as accurate as F=ma

While I agree that no methodology can predict specific performance outside of the + or -10% when it comes to turn performance, the relative performance is accurate. If flight testing deviates considerably as it does in this case, then further investigation would be required in the real world.

Focke Wulf GmbH and Mtt both caught design errors in various experimental propellers for their aircraft which is why they did not end up in production.

But if you want to use it as a reference... you must take in account these simplifications.

1. L/D polar is presented as CD0+A*CL^2, that is not right for the most of real polars throughout the whole range of CL, especially at high AoA (where we are trying to predict peak turn performance!)

I agree, however this is standard aircraft performance math and while the specific performance will vary and I will not argue that with you! I very much admire your work in DCS.

I do stand by the conviction that the relative performance is accurate barring some engineering disaster on either North American Aviation or Focke Wulf's design teams. The assumption is they can both design a good airplane.

2. Prop downwash increasing CL and CD as well as transversal prop force (additiomnal lift) are not taken in account that gives not so great errors for the GA planes but plays a great role for high-powered fighters.

I agree but once again the assumption would have to be a large engineering error in propeller design for either company.

3. The left curve of max AOA is derived using the 1g stall CLmax and Mach effects are not taken in account. It has no significance, again, for Cessna, but affects WWII fighters.

4. Prop efficiency is presumed constant in the whole range of speed. Even if it uses an envelope (efficiency vs advance ratio), I am sure, it is presumed constant vs absorbed power that is not right.

That is correct, the basic premise is taking the power available curve to power required for level flight and anything excess becomes your power to sustain a turn. Standard aircraft performance math taught in college!

The velocity is also in Equivalent Airspeed. This eliminates any environmental effects, places the speeds close to the indicated airspeed seen in the cockpit, and allows for a good clean comparison of relative and not specific performance. I am not here to complain about either airplane only sustaining "XX amount of G's" at "YY Airspeed".

I am saying the relative performance of these two aircraft is not correct in the latest DCS 1.5 build. The Mustang has its low speed turn advantage as it should but the FW-190D9 is unable to realize its rate of turn advantage at speed.

That is very important to the relative performance line up of these two aircrafts. Even your math returns the same relative performance results as mine. Before, it was based on pilots skill to be able to fly his aircraft at its design working speeds. That is how real aircraft are flown and one of the major differences I immediately noticed about DCS.

That no longer works in DCS between these two designs.

Here is the first video of the P-51. Notice the cowling line, that is my visual reference as I make the turn to keep the aircraft coordinated and level. It is the same sight picture I use when turning a real aircraft, the relationship of the nose to the horizon.

The P-51 is able to maintain ~215 Knots at 3.5G's. What is unrealistic is the Rate of Turn advantage it has over the FW-190D9.

In order for the P-51's Rate of Turn to equal the Dora's at 200 Knots EAS, I have to give the P-51D a propeller efficiency of 100%.

The first analysis has both aircraft at a propeller efficiency of 85%. I felt that was realistic.

North American uses .78 in their Thrust Horsepower Curve for the V-1650-3 in the P-51B series.

[ame]http://www.wwiiaircraftperformance.org/mustang/Power_required_available_P-51A_P-51B_P-47B.pdf[/ame]

I felt that this was too low and given later propeller work at the NACA 85% was a good assumption.

For the Jumo 213A, I had Focke Wulfs' thrust horsepower curves supplied by VDM. That shows a typical World War II fighter propeller efficiency range of 78.5% at low speed, 92.5 in the vicinity of design Cl and 85.7% at Vmax. That gives a level flight Np efficiency of 85.7%, rounded to significant digits for the analysis to 85%.

This effect, as I will show below, plays a trick with D9.

Are you saying the propeller stalls or the tip speeds cause it to lose efficiency? If that is the case, it is surprising that Focke Wulf did not catch it as they did tested at least 5 different propellers on the FW-190 series discarding 4 of the designs.

Power_required_available_P-51A_P-51B_P-47B.pdf

Propeller efficiency charts.pdf

Not to discount everything you have said, but what i the Dora is not being flown as well as you are flying the P-51, and that is not a knock on anyone. I am not saying I could fly it better, but it is a possible variable. The turn rates at those speeds are very close anyways, if the Dora isnt being pushed perfectly as maybe you are pushing the Mustang, you could see the difference... yes?

The difference is so significant in the sustained realm that I would have to really botch up my turn to actually cause him to outturn me. Now watching my videos I think you can tell that was not the case as I kept my turn nice and coordinated (bar a tiny slip) and very consistent in speed.

The result was exactly the same with auto rudder enabled btw.

2 Crumpp

 

Ok, you can try your math, but I wonder how you did not notice the fact that D9 and P-51 have exactly the same effective aspect ratio (effective, to prevent misunderstanding due to language difference, is geometric AR corrected to fuselage/nacelles area and to planeform) but P-51 has sufficiently lower weight to wing area ratio.

 

Should I write what it means regarding the required power near maximum CLs AT THE SAME IAS or you will do it yourself? :)

 

And ok, I will even presume all that stuff like propwash as minor factors... :)

Are you also taking into account the increase in effective CLmax as pr. the propwash?

PS: This is the very same effect I've been trying to explain allows the slats on the 109 to raise the overall CLmax of the 109's wing to a figure considerably higher than the freeflow 1.48, explaining the very low power on stall speeds for that plane and its ability to keep flying at 130 km/h clean (Finnish test).

2 Crumpp

 

Ok, you can try your math, but I wonder how you did not notice the fact that D9 and P-51 have exactly the same effective aspect ratio (effective, to prevent misunderstanding due to language difference, is geometric AR corrected to fuselage/nacelles area and to planeform) but P-51 has sufficiently lower weight to wing area ratio.

 

Should I write what it means regarding the required power near maximum CLs AT THE SAME IAS or you will do it yourself? :)

 

And ok, I will even presume all that stuff like propwash as minor factors... :)

I understand what Aspect Ratio means! :smilewink:

It is not my intention to attack your work. I have a lot of respect for you and trust you know what you are doing.

What I use is the standard formula for Aspect ratio:

AR = b^2/S

b = wing span

S = reference area (wing area as reported by the manufacturer)

Mustang:

AR = 37^2/235 = 5.8 (Same as North American Aviation)

Focke Wulf

AR = 34.4^2/197 = 6.0 (Same as what Focke Wulf GmbH uses)

P-51 has sufficiently lower weight to wing area ratio.

Absolutely! That is why the P-51 does have a Rate of Turn advantage at its best rate of turn speed and is able to sustain a higher load factor at a lower speed than the Dora.

The fact the FW-190D9 has a 400hp (+) power available advantage is also why has a better rate of turn at high speed and is able to sustain a higher load factor at a higher velocity.

The higher wing loading of the Dora is the reason why its working speeds occur at a higher velocity.

This is what made these two such an even and very fun dogfight. It also showed off the richness of your Flight Model. It required "cockpit immersion" and the ability to fly the airplane to its working speeds in order to prevail.

The pilot that correctly entered the turn, got to his working speed the fastest, and maintained it prevailed.

That is how real aircraft are flown and that was nicely reflected in DCS in the previous builds.

In the latest build, the Mustang appears superior in Rate of Turn in the vicinity of speeds/load factors it should not be able to sustain. For all practical purposes, the Mustang sustained Rate Of Turn is superior at all velocities.

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Not to discount everything you have said, but what i the Dora is not being flown as well as you are flying the P-51, and that is not a knock on anyone. I am not saying I could fly it better, but it is a possible variable. The turn rates at those speeds are very close anyways, if the Dora isnt being pushed perfectly as maybe you are pushing the Mustang, you could see the difference... yes?

Absolutely.

I am not really even looking at the other aircraft all that much. My focus is on the airspeed, angle of bank, and load factor of the plane I am flying.

Vid is set to private.

:helpsmilie:

I published it....can you fix it so that it is embedded.

BTW,

The simple math is a 16 page spreadsheet I built as part of my undergraduate studies for Aero Sciences.

The methodology is mostly straight out of Perkins and Hage.

I use for World War II stuff because it matches the techniques used at that time and would be familiar to an engineer of the day. Plus it is designed for high aspect ratio subsonic power producer performance analysis which fits the bill for most World War II fighters.

I stay away for using compressible aerodynamics data from this time period because most of them did not have a good grasp on it. Consequently, the theory and math is all over the place.

Any compressible aerodynamic data from the 1940's is highly suspect!

I apply a modern universal compressibility correction equally to the aircraft so that my compressibility all under the same theory and does not throw off my results.

You can see for example, the RAE uses a compressibility correction and the German begin using one late in the war.

The Americans are all over the map despite the fact a Boeing engineer published the theory in 1942 that because the modern universal compressibility correction. North American does not use a compressibility correction on most of their data and surprisingly even wonders why their speeds do not align in some of their test flights!

6. An additional airspeed and altimeter installation error was found to exist at altitude and was evidently dependent upon Mach's number. If this error in the airspeed and altimeter is neglected, an error in true speed of as great as 13 M.P.H. in level flight at 30,000 ft. may result.

http://www.wwiiaircraftperformance.org/mustang/p51b-12093.html

That is one reason why the RAE figures on the Mustang do not agree with North Americans. More importantly, it is also why I do not envy your job, Yo-Yo!

http://www.wwiiaircraftperformance.org/mustang/tk589.html

http://www.wwiiaircraftperformance.org/mustang/p51d-15342.html

The math and science supports several conclusions as we "play detective" in these 70 year old designs. It is really a matter of where DCS wants to put the line up.