Spit/109 sea level speed comparisons in 1.08 beta patch

[TomcatViP]

Originally Posted by MiG-3U

Post #516

No. Again lack of modesty in your assumption. Take a look on Youtube searching TcViP and related variables. You'll see that I posted that last time almost 3 years ago. Good Hunt

...Obviously you won't but that show you how personal arguments hve nothing to do on a forum. Even if that behavior seems rather popular Lol

Originally Posted by MiG-3U

Exactly the same calculation is used on the Mtt test on the prototype V15a to calculate speed at higher power at sealevel (blatt 5) posted several times here. I used the same calculation for demonstration on the post #448 and noted that it's a crude, unaccurate and partially wrong way to calculate it. However, it's good enough for small differences.

Small diff... Yeah. But not small diff at max speed for this kind of plane !

Originally Posted by MiG-3U

Yes, of course. But why do you complain about Holtzauge's calculation now but not about Mtt calculation which has been here much longer (or mine which was posted 3 weeks ago)?

All this story abt the 109E not reaching 500Kph is ridiculous. Juts like other big themes fairly popular here. Nothing new here so you can past those line.

Originally Posted by MiG-3U

Actually I'm refering tests of entire airframe, tunnel and flight tests. And yes, many are available. For Hoerner's Bf 109G analysis, get his Fluid Dynamics book. Some are freely available, here is one for few aircraft including Spitfire I. Below is also a Cd/mach number chart from that report attached, you can see that up to Mach 0.5-0,6 there is rather minimal drag rise due to compressibility.

Didn't I say local mach number ???? Again when your plane is traveling at Mach 0.5, your wing see a peak of high subsonic speed for a 15% airfoil section. Same with the fuselage, especially the bottle neck effect at the rear par. Yes, the 109 was very well streamlined but your calculation need to be repeatable to other type

Originally Posted by MiG-3U

Hoerner's number 10% is for entire speed range from mach 0.3 up to 0.55 ie speed changes 250-300kmh while we are talking here about 15kmh speed difference around mach 0.4, that means that drag rise is certainly certainly less than 2%, probably less than 1%.

Compare to what ?

Wil hve a look to your doc cited as refs. hoping that I won't lost my time wit another bunch of lifting line and alike theo.

If you are interested in the matter you shld read the books from Karman directly.~

A good one and easy to reach (amazon - very cheap):
Aerodynamics - Selected Topics in the Light of their Historical Development, Cornell University Press, Ithaca, 1954

The university of Warsaw hve also a very good list of PDF doc posted on theit website. Doing some Google searching you sld found it easily.