Crumpp

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.

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

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.

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) 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. vxIId8vvpqk

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

Simple but very very powerful. The math is acceptable for predicting aircraft performance. It does accurately predict performance within normal margins of error. It is the BGS system and is taught in every major engineering curriculum in the United States. No it is not the "be all end all of performance predictions anymore than any other system in existence is the "spot on accurate" predictor of specific performance. It does tell you what are probable performance trends for the flight conditions analyzed. MinDrag points and L/Dmax matches the POH speeds too in the analysis which I why I used it. BTW, Focke Wulf used Carson's Speed for cruise speeds in the POH. If you are trying to align your L/D curve to Flugzueg Handbuch figures it will be difficult without knowing that. The power available and propeller efficiency we can argue. I do however have thrust-horsepower charts for the Dora and prop efficiency charts for the P-51. I would be happy to share them. There is not much to choose as Aeroproducts, VDM, and Hamilton Standard all could produce a good propeller. So I would be very surprised if there was significant difference in them. Hummingbird, This is not supposed to be an adversarial discussion so do not make it one. There is room for interpretation in the math and anybody that tells you differently is flat out wrong. That is why our sims at the training department cost millions of dollars and still cannot accurately reproduce some portions of the aircraft's behaviors/performance.

It will become clearer when I get back and post the Mustang POV video. The Mustang simply cannot sustain (+)3G at 200 knots yet it is doing it. Unfortunately, I had to leave for work and won't be home to finish the 900MB worth of traps footage for the next 4 days.

Thanks!!

I got to do the same with the P-51 video. Initial examination shows the relative low speed turning ability is correct. If the Dora gets slow, the P-51 will win. At high speed though, the P-51 seems to sustaining a rate of turn and load factor it could not. At 200 knots it is sustaining over 3 G with a rate of turn that is superior to the Dora.

The Mustang is the most honest and pleasant flying World War II fighter in the game.

I do not think this is Yo-Yo's FM work. His calculations agree with that. I think his work sometimes just gets corrupted with all the versions and file swapping that happens in development of a complex piece of software such as DCS World.

I think it is just testing to see that the video system works in the game.

In the first release of 1.5, the two aircraft were perfectly balanced but with different characteristics. Not caricatures with single qualities like previous games which is not very immersive. If I kept the aircraft at its working speeds, it performed as it should. I could do the same thing in the Mustang as I could the Dora. It came down too knowing the aircraft, flying its strengths and your skill as the deciding factor. Whatever "version" of that FM, they need to bring it back!

Thank you! :thumbup:

Erich Brunotte

PM sent

8 pm EST?

I can't now Hummingbird. The release was fantastic. It changed after the first update and hasn't been good since for me.

Tracks do not work in 1.5 Sith...

Somebody said it looks like the Dora has reverted to a earlier FM. It sure has all of its old bugs back.

I get the same thing offline in the dogfight missions

I just ran the math. It narrows the gap but the relative performance is still the same. The P-51 cannot sustain the same angle of bank at the same velocity as the Dora at 4000ft. The Dora still holds the a ROT advantage that occurs at higher velocity. The Mustang is ~ 1/2knot faster because it gains a little power as it climbs to 5700ft but it just cannot overcome the initial power advantage of the Jumo213 at that altitude. The gap narrows even further until then but after that the V-1650-7 loses power and the gap widens again. The Dora holds an acceleration advantage for most of the envelope too. At Best turn speeds it is significant. Just looking at the power development, the best altitude for the Dora to fight the P-51 is ~10000 feet. The Jumo213 holds ~450 hp over the Merlin V-1650-7 advantage at that altitude. At 4000 feet:

Btw, I will run the math but I am pretty sure 4000ft density altitude is high enough to to effect the sustained turn relationship of the P-51 vs Dora fight. I have thrust horsepower curves for both so Np over altitude can be analyzed fairly accurately as well.

The issue I have in 1.5 were not on the Nevada Map.

And do not justify something as historical just to get a feature added that is not how airplanes work! :)