Spit/109 sea level speed comparisons in 1.08 beta patch

[Robo.]

It says underneath, that although those speeds are re-calculated for normal temperature and correct manifold pressure, they are not corrected for the guaranteed engine perfoamance yet.

Seems to me that no matter how I look at that, the guaranteed performance by Mtt is rather theoretical.

Good point.

[Kurfürst]

Besides the fact that both of these papers show 109s with the 990 PS DB 601A and not 1045 PS 601Aa....

And, despite the weaker engine operating at an unknown power, the first test (476 kph) still just satisfies the guaranteed specs of Messerschmitt (500 kph +/- 5%, that is: anything between 475 and 525 kph is O.K.).

[Al Schlageter]

Thanks Robo. The speeds are not within the +/-5% tolerance being in the 7% range.

Another point to discuss.

Someone said the, iirc, that the trim tabs on the Bf109 were set for a speed of 400kph. This would be ~80% of top speed. This would be max continuous speed would it not?

How much time would be spent at max continuous speed? The a/c wouldn't be at this speed when escorting the bombers but at a lower speed for which the a/c would not be trimmed for. I would think that the a/c would be trimmed for a speed the a/c would spend more time at, possibly 300-350kph. At these speeds, it would be much easier on the pilot.

Kurfurst once posted some test data on the Bf109G that was a plot of the top speed of several a/c. There was more a/c below the guaranteed top speed than above the guaranteed top speed. Just something to think about.

[NZtyphoon]

In other words the Germans took it for granted that there was a possible variation of 50 km/h in guaranteed speed at sea level, which is no form of guarantee at all when life or death in air-to-air combat could rest on very small margins of speed. It also means the top speed of a 109E at FTH could vary by an even wider speed range - anywhere between 532 km/h (330 mph) to 582 km/h (361 mph).

[Kurfürst]

Originally Posted by pstyle

cheers Kurfurst.

... and here it is. But don't expect anything new...

[Al Schlageter]

Why do you continually show V15 data and not data for the E-1,3 Kurfurst?

[Varrattu]

Originally Posted by Kurfürst

... and here it is. But don't expect anything new...

Referring "Blatt 2" important results concerning speed etc. are reported on "Blatt 6".

Please can you provide "Blatt 6", too?

Regards Varrattu

[Kurfürst]

Oh, sorry.

[Varrattu]

@ Kurfürst

Thank you.

Varrattu

[Holtzauge]

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....