Crumpp

No he did not say it was correct. He said the Dora's propeller does a trick. I think he is right. It makes power disappear.

Exactly, just like you should not fight the dragon without your magic sword!! :smilewink: In DCS that is correct since the Dora is missing over 450 horsepower in the turn. The only way to achieve the results we see in the game is set the P-51's propeller efficiency at 100% against the Dora with 78%. You need at least a 20% efficiency disparity to overcome the math and physics. It is just that simple. A blade element analysis shows no reason for this at all, which I will post when it is complete. In fact, while the P-51's propeller does show on a dimensional analysis to be about 6% more efficient in a narrow speed range, it has more blades, higher rpm, and a smaller diameter. That means the math says for much of the envelope it is less efficient than the Dora's. Once more, all propellers fall within about the same efficiency range and there is not much to choose from at all. That is why it is industry standard to use around 80% efficiency, a little lower for a fixed pitch GA aircraft and slightly higher for a high performance Constant Speed Propeller equipped aircraft. A few percent does not change the picture and the point is physics say the P-51 and the Dora will be very close in their propellers ability to produce thrust from a given amount of power. It is very easy to spot a bad design or engine/propeller combination too. VDM was a top propeller designer and while the company was shut down by the allies after the war, the personnel went to work for and intellectual property rights where given to Mtt Propeller. http://www.mt-propeller.com/

I noticed it too. It completely interferes with being able to pilot the aircraft correctly. It was present in both the DCS modules I own, the P-51 and the Dora. I thought it might be something similar to the stick forces modeled in DCS. It that is the case, the force is set way too low. NACA testing shows 400lbs is attainable by the average pilot with 180lbs becoming the specification. 45lbs was considered the ideal for controllability as below that precision rudder inputs become more difficult.

Compare the Mustang calculated climb performance with flight test at similar weights: http://www.wwiiaircraftperformance.org/mustang/mustangtest.html The flight testing performance is consistently better than the calculated climb performance.

Vw is True Airspeed "W" stands for "wahre".

Yo-Yo proved Focke Wulf did not use exhaust thrust. I would not be surprised if Mtt also did not. Exhaust thrust wasn't much of a factor in aircraft designs until the late 1930's. An engine has to be powerful enough and have the correct exhaust design to realize its benefits. The DB605 series had the right engineering to realize exhaust thrust gains. Knowing the difficulty faced in making a climb analysis, I wouldn't be surprised to find it was commonly left out on many World War II aircraft calculated climb performance analysis. That is why you see so many reports investigating its effects during the war. It was a new thing and everybody was experimenting and measuring its effect. It is also a good way to ensure the customer who ordered the aircraft is happy with the finished product as your estimates will always be conservative.

Who said anything about balance?? Relative performance is not balance. This misunderstanding can completely change the meaning of what I wrote. An F-16 vs A Sopwith Camel has a relative performance that is more important than whether the camel goes 75 knots or 95 knots. If the F-16 suddenly losses 20,000lbs of thrust in a turn just so the camel players can be happy and catch it in a turn.... The relative performance picture is skewed. :thumbup:

I agree with you. In any variable enviroment, some will be behind and others ahead of the mean. As they say somebody has to loose!! Obviously ED does..... And they are not wrong from an aeronautical science POV once you understand all aircraft performance is percentage variation over a mean.

Good job finding the flat plate area!

Relative performance is the everything in these games and the key parameter you are trying to simulate. It is the only way you will get things as "real as it gets". All specific aircraft is a percentage range over a guarantee mean under specific atmospheric conditions. It is not absolute. Absolute specific performance is an impossibility. http://www.spitfireperformance.com/spittest.html Our Bf-109K4 falls within that spectrum for specific performance. More importantly, it falls were it should for relative performance within the aircraft line up. It is a realistic simulation of the design, that is a fact. Could it be "closer to a production machine"? Sure....

Where is the aisle and who are the sides?? Thanks but no need to answer. Your post is simply irrelevant, off topic, and trying very hard to be inflammatory without cause.

Going from a known point, adding power to achieve performance at an unknown point. That is perfectly valid technique readers..... Probably not ever going to happen and it is unknown if such data even exist's. A concerted effort at drag reduction was part of the Bf-109K4 program, which complicates things somewhat. The performance estimate appears to be the top of the margins. Mtt reported to Rechlin on performance: The Kennblatt, which is a flight planning document, also agrees with the 580kph reported to Rechlin. 568kph - 580 kph = 12kph [12kph/580] * 100 = 2.06% = Gives good agreement with the Kennblatt and published figures for the Bf-109K4. So while the OP claim the DCS Bf-109K4 does not match the specific performance of 580Kph, it does give good agreement with the range of specific performance that can be expected from a Bf-109K4. More importantly, it also gives good agreement with the relative performance of the BF-109K4 vs P-51. The P-51 should have a low velocity turn rate advantage if the Bf-109K4 tries to match the P-51D's best turn speeds: It preserves the relative dogfighting performance such that while the individual specific performance is accurate within significant digits, the relative performance is more accurate. That makes for a more balanced and fun fight no matter which aircraft you choose. That fun factor is why we play the game. :thumbup:

As my Basic Aero professor was found of saying, "In terms of significant digits....". Those turns are good enough for analysis of sustained performance.

The original FM is not being questioned. That agreed with standard performance estimates. It appears that the propeller efficincy and effective angle of attack have changed in the FM. In order for the propeller efficiency to absorb the 450 hp advantage of the Dora, the P-51's propeller must be 15% or more greater power transfer. It is highly unlikely that would not have been caught in testing are would represent a significant departure from normal propeller engineering. The second point seems to be an issue with the effective angle of attack of the polar. In very low aspect ratio wings, this is correct assumption. Unlike the jets found in most of DCS, however, the high aspect ratio designs of World War II it is insignificant. For Aspect Ratio's above 3, the 2D is very applicable and is industry standard. To get a perfomance estimate our method must change based on Aspect Ratio of the wing. Our formula for Angle of Attack for High Aspect Ratio Wings then becomes: Angle of Attack = 2D Polar Angle of Attack + Induced Angle of Attack For a 3D wing with an Aspect Ratio of 3 or Less, that model breaks down and our methodolgy changes to a better approximation becomes: Angle of Attack = Effective Angle of Attack + Induced Angle of Attack. Effective Angle of Attack is calculated thru the section 2D using formulation designed for a LOW ASPECT RATIO wing. Here is a fairly easy to understand lecture from Stanfords Engineering Department. Page 40 Figure two nicely illustrates why wings are divided into low aspect ratio and high aspect ratios for calculating performance. Two different methods are required and they are not to be confused! [ame]http://adl.stanford.edu/aa200/lecture_notes_files/lecture11_1.pdf[/ame] Think about it, for the Dora to suddenly loose 450 hp in a turn...... it would be immediately noticed by the pilot and picked up by standard data recording instrumentation of the day.

The basic characteristic of laminar flow being a low angle of attack event is a characteristic of all laminar flow airfoils. A discussion of laminar flow at high angles of attack or any effect at all on turn performance is a waste of time.

I just read the NACA paper you posted. I definitely do not think Yo-Yo is making the claim you believe based off this evidence. The induced angle of attack changes are the topic and the error that exists between linear and non-linear equations. Induced angle of sttack effects the body angle and has absolutely nothing to do with turn performance.

The predictive error of the method I am using is fine. It is as accurate as any other mathmatical model. The difference between single axis analysis and 6DOF equations of motion is -1.5 %.

??? I missed this! 165mph Indicated Airspeed for the measured data I used. I think North American can find Best Rate of Climb Speed in their own design. At it is 148.5KEAS on the spreadsheet. 148.5 * 1.15 = 171mph CAS - 6 mph PEC = 165mph IAS The British POH list's "approxiamately and the P-51D POH list's 175 at Sea level for a Military power climb...not the 67" WEP used in the North American test. http://www.wwiiaircraftperformance.org/mustang/p51d-15342.html The curves fit all the performance parameters for both aircraft's design speeds.

I am back to work so it will be at least 4 days.

It is the same whether you turn right or left. I recorded one but the fraps made it slide show.

Maybe. I would think the old bugs of the Left cannon not firing and the MW50 gauge not working showing up again in this last build might be a clue. Both of those were fixed for several builds and then all of sudden after this last update, they show up again? :dunno:

I agree that the pilot factor is very important. However, I am looking more at the velocities, altitude, and load factors. In Hummingbirds first film, the Dora spends the majority of the time ~370kph at 2.8G's. http://forums.eagle.ru/showpost.php?p=2591966&postcount=70 At those speeds, the Dora still holds a rate of turn advantage, yet the Mustang is able to sustain a higher rate in the game. That is according to Yo-Yo's chart: Within significant digits.....Yo-Yo's and I performance analysis agrees, SiThSpAwN. I really do not think this is Yo-Yo's flight model. I think an error has been introduced in the time between he completes the FM file to the point it ends up on our machines online. That is only thing that explains why the math reflects the same relative performance, Yo-Yo cannot find a FM error, and we are seeing different relative performance online. :thumbup:

LOL...YES SIR!!

It is held quite comfortably. I am just playing and showing the superiority. I pull ahead and drift back to illustrate that.

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! 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.