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Panthera

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  1. I was thinking more of the power on Clmax, not the idle stall speed Clmax. It's with power on where the slats should really make a difference, and the more power the bigger the difference. btw what clmax did you measure for the Bf-109K4 ingame? (don't have access to the game atm myself)
  2. First of all let me say that Holtzauge's program is great, and I can't find any fault with it what'so'ever, matches my own calculations perfectly when we use similar numbers. Really is a great program he has put together there, can't stress that enough. He's got a fan in me That said IMO the Bf-109 ought to have a Clmax noticably higher than the P-51 during powered flight, which is also where I've heard modern pilots express the big difference between the two. Skip Holm does say that the difference is big between the two, and he is/was flying the Buchon which weighes the same as the K4 IIRC, and runs a merlin like the P-51. The RAE also measured quite a high CLmax during powered flight for the 109 IIRC, their problem was seeing the slats as a stop sign during turning, which was even a problem for some German pilots. Anyway a difference in Clmax figures used is probably the reason why Holtzauge and I are getting some different figures for the 109 vs P-51 match up. Just my two cents. Bigger problems for me right now though are how the Tempest seems to have a Clmax of 1.7+, and that the 262 is still suffering control stiffening already at 450 kph.
  3. Look at the graph from the report you posted yourself, there are curves for 25 kft there as well, and the trend is the same, the laminar flow airfoil produces less lift until above 0.5 Mach. Also keep in mind that all these Clmax figures we've been quoting are with power off or at idle, where'as the 109's real advantage comes with power on where prop wash is energizing the inner wing section allowing it to match the outer slatted section in lift generation and thus providing for a significant net gain in lift. With power off the 109's root section would stall first whilst the outer section is still flying due to the slats, and as such the net gain will be much smaller here. i.e. with power off the outboard slatted wing should demonstrate a similar to slightly higher Clmax than the unslatted one, but with power on the difference should be significant.
  4. Great stuff once more Holtzauge! I am getting slightly different results than you (my P-51 curve is slightly more to the right, and infront of the K4 instead of behind it), but I'm sure that's down to using a different CLmax for the P-51 & Dora. That said again your C++ simulation is matching my curves so beautifully, and I really have to commend you for your work on it, wish I had such a tool myself and didn't have to do each parameter at a time Awesome as always!
  5. If you check the results for similar altitudes the difference is the same (and the windtunnel data was compared to verify as well), the conventional types are achieving a higher Clmax up until somewhere past 0.5 Mach, it's the same story over and over again. The laminar 66-2-2xx series can possibly reach 1.4 clmax at lower altitudes at certain speeds, but the conventional types will once again be even higher below 0.5 Mach.
  6. Can't say why the British got 1.4, also at what speed? What I can say is that NACA consistently demonstrated that the laminar flow airfoil produces less lift than the conventional types up until somewhere past 0.5 Mach. It was the same result in side by side tests with the Mustang and F6F and others for example: To me all these NACA tests backing each other up is evidence enough to be pretty definite. Regarding the Charles Meudon figure, 1.45 might be more appropiate, I think Holtzauge is right here. But again this was for a shorter wing without slats. The 109's real advantage is going to be lift produced with power on and slats out.
  7. That was a discussion regarding the Fw190D and P-51D though, and indeed those two are quite evenly matched. But the Bf-109K-4 is in another ballpark. As for the Clmax of the P-51, I got the real life full size tested ones, and they are much lower than 1.4 at the most common dogfighting speeds. The advantage of the laminar flow airfoil is low drag in level flight and good high speed lift, whilst the conventional airfoils provide better lift below around mach 0.5. This is the case in regards to the Bf-109, Fw-190 & P-51 airfoils too, as you can see here: As you can see below ~0.55 mach the conventional 23xxx series airfoil (as for example used on the 190 & F4U) is providing more lift than the laminar flow NACA 66-2-2xx type of the P-51. The Bf-109's 2R1 airfoil was tested to be 1.48 at 0.3 Mach at Charles Meudon, without slats.
  8. Hmm, might have to check. All I know is that stick deflection started to become limited already at 450 km/h ingame before, something which contradicts all the written records of flying the thing I've seen. Here controls were considered light & pleasant at all the normal operating speeds (i.e. often beyond 800 km/h), with just 2.7 kg pr. G required at 650 km/h.
  9. I sincerely doubt that, but let's let the man himself pitch in. Watch the entire video, Skip is at the end
  10. Yes, I talked to Skip Holm once, he's really an incredibly experienced pilot, and importantly a very nice person. So his words shouldn't be taken lightly. But the other modern 109 jocks say the same, the 109 is very good at turning, much better than what much post war scripture gives it credit for.
  11. I cannot get the P-51 to match the K-4 at all in sustained turn performance using any form of estimation model, they are quite far apart in every single one. I'm sure @Holtzauge's C++ simulation will show the same, irrespective of wether the P-51 is running at 67" or 75" hg boost. The slats on low wing centerline propeller driven aircraft are rarely full span as propwash would prevent their proper operation. On this type aircraft the slats are instead mounted on the outboard section of the wing which isn't energized by propwash during powered flight. The effect of this is that during powered flight you raise the overall lift of the wing as a whole, as the inboard section is being energized by the propwash whilst the outboard is kept from stalling by the slats. In addition to this you make the aircraft almost impossible to stall during unpowered flight, instead it will generally just sink (something you hear 109 pilots talk about a lot when they are coming in for landing with power at idle) All in all the 109 probably gained a 25% lift increase during powered flight with the slats vs without them. That's significant. On top of this the more conventional airfoil shape of the 109 provided more lift at the normal dogfighting speeds (350-450 km/h) than did the laminar flow airfoil of the Mustang which was optimized for low level flight drag. So on top of the big advantage in power to weight, the K-4 should also have the advantage in terms of lift to weight as far as I can see, and should as pr. any estimation model I've used be quite noticably apart in turn performance.
  12. Odd, according to what I've atleast been able to calculate myself to the 109K4 should be noticably better in the turn, esp. sustained. Even if the Pony is only loaded with 30% fuel. At high speed a Mustang pilot with a G suit obviously has an advantage, but how big it was with these first generation G suits I don't know. AFAIK these first gen G-suits were also not good for sudden G's as they inflated too slowly. Should ofcourse also be noted that German pilots had the advantage of raised footrests, so their G tolerance without G suits would've been higher than that of an Allied pilot without G suit (all else being equal).
  13. Well that's a shame Really can't bring myself to fly it in its current state.
  14. Has there been any changes since July? ? Or any luck getting access to the RAF reports? Haven't played for the last 4 months due to a very busy schedule and a PC replacement.
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