Originally Posted by Holtzauge (Post 464929)

There are a number of issues with the outlyer 109E 500 km/h sea level top speed:

First of all the Baubeschribung 500/570 Km/h speed curve does not map any known engine power/alt curve: These either have the characteristic bulge associated with the hydralic clutch or the notch type with two speed superchargers where as the curve showing 500 Km/h at SL and 570 Km/h at altitude in the Baubeschribung has a straight line between these points.

Originally Posted by Holtzauge (Post 464929)

Moving then to some more realistic speed estimates based on what could be expected of a series type aircraft at 1.3 ata: Note that the C++ simulation data for the high and low altitude speed of the +6.25 and +12 boost Spitfire is quite consistent with historic data. Using the same principles for calculating the Me109E low level speed the result also yields around 570 Km/ at altitide but at low level the result is around 475 Km/h not 500 Km/h. These curves were calculated using the actual historic series type engine data and consequently show the effects of the hydraulic clutch, something missing from the 500/570 Km/h chart. I'm sure the usual suspects will question the validity of the C++ simulations but as an answer to that we have the Me109E figures posted by HoHun on the All About Warfare forum (www.allaboutwarfare.com) and as can be seen the calculations agree remarkably well. In addition one can conclude that both calculations agree quite well with the actual measured top speed posted earlier by Al Schlageter.

Originally Posted by Al Schlageter (Post 464996)

German speed graph of a Bf109E with a DB601Aa engine.
http://www.allaboutwarfare.com/forum...e=post&id=2042

Originally Posted by Robo. (Post 464972)

Holtzauge, that pretty much sums it up.

Originally Posted by ACE-OF-ACES (Post 465030)

Very cool! I just joined the All About Warfare.. First thing I noticed was butch2k is there! I was wondering where he had gone! Al, did he ever finish that book he was working on? Or do I have him confused with someone else?

Originally Posted by Kurfürst (Post 464935)

BTW it's worth comparing the V15a (WNr. 1774) results with the speed results with a Swiss export Bf 109E-3a. The reports show remarkable similarity in the top speed achived at altitude with the original VDM propellor of J-347 (572 vs. 564 km/h at rated altitude), especially when taking into account that J-347 already saw considerably use. However the low level speeds diverge greatly (498 vs 464 km/h at 0m altitutude). Note that the low-level performance of V15a with the Höhenlader (high altitude supercharger speed, or 'F.S gear' in British terms) shows good agreement with J-347 at both high- and low altitudes.

Originally Posted by Holtzauge (Post 464929)

There are a number of issues with the outlyer 109E 500 km/h sea level top speed:

First of all the Baubeschribung 500/570 Km/h speed curve does not map any known engine power/alt curve: These either have the characteristic bulge associated with the hydralic clutch or the notch type with two speed superchargers where as the curve showing 500 Km/h at SL and 570 Km/h at altitude in the Baubeschribung has a straight line between these points. So which DB601 in a series Me109E had this power/altitude characteristic? None that I have seen published.In addition the date of the the Baubeschribung is stated as "circa 1939"and reference made to the Yugoslavian manual. So this looks more like some early marketing material supporting Messerschmitts export activities which also predictably for marketing material includes a caveat of plus minus 5% which would then place the more realistic speed performance of around 475 Km/h within the guaranteed range.So to conclude, the data supporting 500 Km/h SL speed either references prototype data or refers to some early marketing material. In addition, it looks like estimate for the "guaranteed" engine data coming close to 500 Km/h for the V15 prototype is for 1,35 not 1,3 ata.

Moving then to some more realistic speed estimates based on what could be expected of a series type aircraft at 1.3 ata: Note that the C++ simulation data for the high and low altitude speed of the +6.25 and +12 boost Spitfire is quite consistent with historic data. Using the same principles for calculating the Me109E low level speed the result also yields around 570 Km/ at altitide but at low level the result is around 475 Km/h not 500 Km/h. These curves were calculated using the actual historic series type engine data and consequently show the effects of the hydraulic clutch, something missing from the 500/570 Km/h chart. I'm sure the usual suspects will question the validity of the C++ simulations but as an answer to that we have the Me109E figures posted by HoHun on the All About Warfare forum (www.allaboutwarfare.com) and as can be seen the calculations agree remarkably well. In addition one can conclude that both calculations agree quite well with the actual measured top speed posted earlier by Al Schlageter.

Finaly, it's interesting to note the type of evidence evaluation practiced by some in this forum: There was a mountain of evidence supporting 100 octane that was dismissed as inconclusive and now we are expected to swallow a molehill of evidence for 500 Km/h sea level top speed when most data, calculated and test measurements point to something around 475 Km/h.

Talk about double standards....

Originally Posted by TomcatViP (Post 465071)

There was some diff btw the 109 exported in Switzerland and the original E. Notably in aerodynamics.
I don't think you can make a comparison without taking this fact into account.