Crumpp

Compressibility correction was either non-existent and was not universal.

By all means point them out!!! :thumbup::thumbup::music_whistling: Oh yeah... You cannot.... You want the Focke Wulf investigations and comparative testing results?? Point them out please because your post does not make much sense. It might be more productive for you to name what exactly you think is wrong?

Yeah you missed the fact it is the same airfoil selection and wing design :smilewink: Engineering wise, they will have the same CLmax and lift distribution. An anton does not stall at 87 mph and neither does a Dora. If you know the basic relationship of Reynolds Number to CLmax.... It is a simple fact the higher Reynolds that the FW-190 series stalls at requires a higher CLmax.

Btw... There are so many ways one could go with this. Mercury could so easily be substituted with: Credibility Science Engineering Flight Mechanics Anyway, it probably better if you stuck to an informed discussion using facts and not bait. :thumbup:

Velocity = (4900000*.000156927ft^2/sec )/5.95ft = 129.23 Ft/sec 129.23 Ft/sec = 87 mph... Is the stall speed of an FW-190A only 87 mph? :music_whistling: Could be.....

The FW-190 simply cannot fly at that velocity so how can anyone conclude that is the CLmax?? This is not a retraction of earlier data but a statement that all the data agrees!! 1.3 + .3 or .4 = 1.6 to 1.7 In other words, the 1.58 for the clean configuration FW-190 CLmax is correct. That is why Focke Wulf used it. This is part of the parametric studies the wing design article refers too, btw. :smilewink:

Eric's comments give real world experience and simply confirm our physics model is correct.

I think 2100hp and 4300Kg will have more excess thrust than 1600 hp and 4350 kg. The context is physics. think 2100hp and 4300Kg will have more excess thrust than 1600 hp and 4350 kg? The math is extremely impartial and tells us what is the realm of possibility and what is not. It has been allowing us to produce machines for heavier than air controllable flight for one hundred years now.

11:04 of Eric's video. He is not describing the current version of DCS's Dora.

1. You cannot keep coordination when maneuvering at speed. The rudder will not lift the wing at the stall. Two basic and key design features of a rudder. 2. I am not seeing any restriction on the ground. It is only under an aerodynamic load that range of motion is restrictive. Since it does not represent a viable rudder design once it becomes restrictive and cannot fulfill the job of a rudder.....It looked like the correct effect of increasing hinge moment but with too little input from the pilot. Our pilot appears to weak to move the pedals.

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.