Kurfürst

Depends on what your reference data is... there is a lot of spread in P-51D measured performance, 375 mph is probably the best figure obtained only once a specially prepeared plane. NA Inglewood, based on experience of numerous previous trials, which seem to make a good reference, calculated the P-51D speed as 355/368 mph at SL (61/67"). There are trials of P-51D that yielded 354 mph at 67" Hg map, so I do not quite see how exactly 369 mph counts as slow. If anything, it seems to be a quite a bit faster than your avarage Mustang.

Don't forget its a "living" model which calculates every aspect based on programmed parameters, so if you change one (like drag) it will change (and sometimes, completely ruin) the other performance aspects. Its not like just "enter correct sea level" speed (old Il-2 engine I believe worked this way, but it was much simpler). Also given that we don't have all the data (probably not even manufacturer had, and even those that were obtained from trials were subject to a certain % of measurement error), there will always be some kind of tolerance on the results. Its also possible that the missing amount lays somewhere else, say in the engine or superchargers or propeller model etc, but I presume the current model gives a good compromise to get all figures within reasonable distance from the reference figures. Its probably not even possible to get it "perfect", but the current model sea level speeds seems like 1.3% within to the figures in the historical reference document, nonwithstanding that for example it may also be not 100% compatible with the atmospheric model used in Germany at the time - and that production tolerance, the amount the manufacturer was guaranteeing in the actual planes was like +/- 3% in level speed. We have our model that is well within that, and in fact quite close to the reference figures, so I don't think there is reason to complain but to express are congratulations to YoYo who was listening to our input on drag and made a very, very good job (again).

Re: 109K drag fix, its nice to see it implemented, probably a fix for the too high drag and too Low speed of 109K (had 109G drag and as result was ca. 30 km/h slower than should).

I know of figures of K-4. - simplified straight speed curve on GLC charts, late 1944, based on engine data, for early 605DM, i.e. 1,75 ata, 1800 PS. Source stated to be manufacturer, i.e. Messerschmitt. Simplified curve suggest early calculation. Airframe condition and origin (test or calculation, well doors fitted or not) - totally unknown. Thats the 580 figure. - Aspera flight tests around turnover 44/45, with 4 different types of propellers, this is flight test with an early testbed (pre porduction aircraft), wheel wells missing, tail gear fixed down. At 1,35ata/2600. Testing at 1,98ata failed (605DB/DC had assembly errors in December - wrong size pistons, poorly installed valves - fixed). - Messerschmitt projektbüro calculation turover 44/45 for K-4 with various DB / DC engine settings, 1,5 through 1,98ata. Possibly made because Aspera test bed aircraft was awaiting new engine, and results of new propeller improvements were made. Detailed airframe conditions are known. Not really an absolute performance test, results were interesting relative to each other (improvement with various propellers). - several other hints of later development testing flight tests in various documents but results missing. Estimates can be made of various 109G trials, which I believe yoyo was doing, with allowence for increased power and reduction of drag by aerodynamic improvments (known drag data). These necessarily effected by which base test data is picked (which obviously subject to production plane scatter in performance - optimistic or pessimistic) cc 591?

Its on the GLC datasheets, also from Messerschmitt data source, the curve is poor quality but visible. IMHO the difference may lay in -the a simplification of GLC in the curve, as it goes straight from SL to 7500 m, which does not accurately portray the 605 power curve, so at some altitudes they likely took mean avarage for speeds - the fact that the GLC curves are for earlier 605DM powered K-4s (1,75ata / 1800 PS vs 1.8ata / 1850 PS for the 605DB version we have in DCS and in the Projektbüro K-4 curves above) - some other factor, different source data used etc. I wouldn't complain about anwhere between 580-590 vs the curve's 595 figures, as yoyo says its well within statical error and real life production tolerance, whereas 30+ km/h difference was clearly not. Its also effected by (sometimes not-so)minor factors like radiator position, and atmospheric environment used by YoYo's model vs the Projektbüros results. Apparantly YoYo's previous model was matching well real life 109G-5/AS model results, so its matches a more or perhaps less good quality real plane, only some drag elements were missing for being a true 109K level, which I believe was/being corrected and thus we will no longer have a G-10 :p but a K-4, well maybe made on Friday afternoon, but still, real life examples were each different as well.

It has both the new thin bladed 9-12199 prop and the 'standard' 9-12159 prop for reference.

Right. So we have the P-51D-25, which saw service in October 1944 (early 1945 if we count for the metal ailerons), correct? We also have the K-4 & D-9 in its late 1944 state. And if this site http://www.mustangsmustangs.com/p-51/production is accurate no more than 2200 P-51D-25s were made (1600 in Inglewood, 600 in Dallas). Now if I follow Solty's arguement, these ca. 2200 P-51D-25s first appearing in October 1944 are supposed to be COMMON, while the 1600 K-4s and 1700 or so D-9s produced (a total of ca 3300), both of which appeared also in October 1944, are RARE. :doh:

Yeah, judging from the smoke, its a VW turbodiesel! :D :D

Yes, we have discussed this and you were shown the exact numbers operational and that the K-4 was no means a rare bird, yet despite these facts you keep repeating the same things that were already shown to you to be in error. There is no pont in repeating that again. Therefore I suggest you look up the actual numbers of K-4s and D-9s operational on the Western Front in late 1944 and do the same for the P-51D-25 and present your findings. The IXLF did not see major use until spring of 1944 and de facto was the most common and typical Spitfire type until the war's end. Its exactly THE '1944 Spitfire'. Its also a ridiculously maneuverable bird with great climb, even if a bit slow. Learn to use that. Yeah I get it, the May 1944 bird against the October 1944 bird (which btw was entering production in August 1944 and only delayed by bombing) is grossly unfair. Right. As noted by others the variant we have is from October 1944, a D-25, from the very same period K-4s appeared. How many D-25s were made? How many P-51D-25s with gyro sights were operational during 1944? Yet here's the strenght report of JG 77, dumping all their 109Gs and receiving 75 brand new K-4s in October 1944. http://ww2.dk/oob/bestand/jagd/biiijg77.html Many other units did the same, that's why you go from 0 109Ks to cc. 200 K-4s in service just in one month, October 1944. Using the same logic, the P-51D-25 was just another type in many many types that served in the USAAF, so we shouldn't have it. We should have a razorback P-47 or an Allison Mustang or what not. P-51D production (all blocks) was what, 8000 including 1945 and post war production? Yeah everybody should be flying P-40s and P-47D, those are the most produced US fighter after all. :doh: You get no counter arguements from me that in all fairness, 72" (not 75", it wasn't operationally approved) should be there for the 51. That being said, even with 72" what you will get is a 4.5 ton plane with 1800 HP against a plane with the same horsepower, but literally a ton lighter. I wouldn't expect miracles to happen. Frankly, what I see is only the wish to romp-stomp poor early 1943 G-6s with the 'bestest' P-51 one can ever have. I have seen this wish in other flight sims, too. 'We will get P-40 and stomp , we will have a P-47 and stomp, we will have a P-38 and stomp, we will have a P-51 and stomp.' These fantasies usually involve the opposing players being noobs, and having to struggle with some old, hopelessly obsolete type against Allied superplanes with superfuels and supergunsights. And when that fantasy collides with reality, the mind starts to make up excuses... You already do not have to bother with a weakly armed P-51B or C with a birdcage canopy and various teething issues, you already have the definitive D model with a late 1944 computing gunsight. You also want it to have the highest possible boost version, and not only that, it would be even finer if the opposition would be an early 1943 G-6... I'd say you are already fairly set and yet asking for even more. What I see to fail is the point. The K-4 is already there, its modelled, and it won't disappear. Its not even the most powerful, fully rated 2000 HP variant. But its every bit the lightweight power-monster it historically was, so try to deal with it - 8th AAF fighter pilots managed, I am sure you can too. It has weaknesses as well. Luthier picked it and now we have it (and I am very glad he picked the definitive 109, just as he picked the definitive P-51, 47 and Merlin Spitfire). Its not going to go away. So just... deal with it, okay?

It would be change if the arguement would be true, but it isn't. The Spit IX and P-51D was the most common Western Allied frontline fighters of the second half of 1944, and neither the K-4 or the D-9 were rare, by any standard. You could argue though that they might as well gave us the Typhoon, P-47D, Fw 190A-8 or Bf 109G-14 or G-14/AS, but it wouldn't change much IMO. Especially that at these low altitudes with the G-14 you would be probably worser off than than with K... Those fantasisies about trashing early 1943 G-6s with late 1944 P-51D (service introduction: June 1944) should really do a self- and reality check why they have problem with facing late 1944 D-9s and K-4 (service introduction: September/October 1944).

I think we both know most developers already decided on that as they simply ignore you. Well Anders the only thing worse than your convincing power is apparantly your reading comprehension since I have never suggested such. In any case, it was YoYo who suggested the German calculations miss the exhaust thrust elements and from what I know, it seems a plausible explanation why German climb calculations are often lower than real life results. I don't quite get why I would need to convince him of something that was his idea in the first place. In any case if you would have bothered to read through this thread this speed bug was already cleared up with YoYo and appearantly it was caused by having the 109G drag levels for our K-4 since the model already gives very close to IRL 109G results under the same power. As I believe a fix is already underway so that our K-4 can really live up to the historical specs, and hopefully you will also manage to come to terms with that.

:lol: Nice try, Anders. Nevermind that the GLC/E Kennblatt figures are not for 1,8ata but 1,75ata, and not for the DB 605DB we have in DCSs but for the early weaker 605DM we do not have and which had an 1.75/1800PS output limit (and also quite a bit lower 30-min ratings). Apart from not referring to the correect engine model, the Kennblatt's figures are also from Messerschmitt but the curves are even further simplified in shape which is almost certainly interpolation of the actual curve and the source of disparity in the figures. But, you are never quite worried that facts could get in the way of a good strory when the agenda as always is to misrepresent Bf 109 performance.

Nobody said its a "real test". Its a calculation that is based on real tests and the whole point of this calculation is BTW to show how much the improved new props would increase the speed of the 109K at various settings, for which they also draw as reference the performance of the current serial production 109K. Which is what we need and which is what we have, as it is the only detailed source availabe for 109K I hope you are not seriously suggesting that they needed to estimate performance of the serial production K-4 in January 1945, when this paper was drawn up, after the 1000th K-4 rolled off the assembly lines and was with the troops already for months? Because that is so silly it could be on wwiiaircraftperformance with a Benny Hill background music. We also know that the 109K is not the same thing as the 109G, it has considerably less drag than the 109G and we know the extact amount of this drag and compared to the 109G it yields exactly the same results as these 109K curves from Messerschmitts Projektbüro. Probably not a coincidence, right? This was discussed with YoYo already and as far as I can tell, he agreed on that so honestly I have no idea why you are getting back to the starting line, ignoring all that was said in this thread.

Since when? The whole problem revolves around that the cleaner K-airframe is just as fast in DCS as real life 109G test at the same power. Which we all know to be incorrect and does not match any of the historical documentation on its performace. In other words, until this gets fixed we have G-10 with 3d cocpit model with serious errors which resembles strongly a 109K cocpit.

Don't be silly, read the rest of the thread. We have the 1,8 ATA 605DB version of the K-4 which should do ~595 km/h on the deck.

:megalol:

Will check! :thumbup:

Soooo, has this been corrected....?

Yet for some reason actual WW2 RAF Spitfire pilots were not all that enthusiastic about the clipped wing variant. The modificiation was supposed to counter the Fw 190s great superiority in roll, yet it practice it just didn't bring the plane on par with the 190, but at the same time degraded its best advantages over it. It was niche modification, that's get hyped all over whereas in reality it did not see much use in operations due to its overall impracticality, except where structural issues with the wing while carrying bombs necessitated it.

Makes sense, thanks for the clarification Yoyo! :)

Pneumatic for both guns on the 109, the 131 was automatic for certain, the MK 108 is a bit fuzzy - early G-6/U4 manuals note the cannon unjamming is manual but planned to be automatic (G-6/U4's MK 108 however was an afterthought mod installation), cant seem to find it in the K-4 manual though.

The thing that I do not understand though is how can the same thing (advancing the throttle too fast) lead to putting out a fire and fire, two opposite things at the same time... I guess engine fire could occur for a number of reasons at any time and any engine, and perhaps they misunderstood the cause.

Amazing. Seriously, IMO the best way to advertise your products would be simply to describe publicly how many aspects are modelled of a single plane... :thumbup:

Could it be that the chance of engine fire was present at the start up process, which was using ordinary aviation gas before switching to diesel J-2 jet fuel? Maybe the avgas was more sensitive to sudden injections. In any case, the engine startup process definitely appears to be a unique experience with the 262. :)

Thx for the answer Yoyo! Regarding oil/water cooler thrust - is it constant thrust amount from these or is also effected by varying inlet/exit flap area, i.e. internal thermodynamics of the radiator assemblies...?