Spit/109 sea level speed comparisons in 1.08 beta patch

[Kurfürst]

Originally Posted by MiG-3U

The facts:
1. Prototype aircraft V15a, tested well before production started

Fact: report says aircraft is identical to production E-1.

Originally Posted by MiG-3U

2. Tested speed 493kmh at altitude of 440m, gives 485kmh at 0m

Fact: MIG 3U misrepresentats the report, which states:

Erflogene Geschwindigkeit 493 km/h, auf Normaltag und Garantileistung umgerechnete Geschwindigkeit 498 km/h im 0 m.

They have flown 493kmh at altitude of 440m, which was not yet corrected for German Standard Day conditions or the Guaranteed output of the engine. Bench tests confirmed engine was developing 45 PS less than it should have.

3. The supercharger has two fixed speeds:
- boden- and hohenlader are claimed and the optimal change altitude is determined
- manifold pressure drops above the FTH of the bodenlader, until hohenlader is set on
- the speed test confirms that the supercharger has two fixed speeds

Nope.

Fact: Boden and Hohenlader are just generic names for MS and FS speeds, present on all DB 601/605/603.

The supercharger has two . US trials of captured Bf 109E, later Rechlin trials of Bf 109G-6, G-14 also run with fixed supercharger speeds, something which is easily done on the DB 60x series with hydraulic coupling by bypassing the barometric control.

Originally Posted by MiG-3U

- according to Flugmotoren und Strahltriebwerke by Kyrill von Gersdorff, Kurt Grasmann, Helmut Schubert the first order of the DB601 was the pre-series of 150 motors, A-0 ie Baureihe A (carburator engine with fixed speed supercharger), so based on engine number of 140, the V15a had one of these instead a A-1. The hydralic clutch came later with the Baureihe B along with fuel injection.

Nope.

DB 601A-0.

"Gemischung durch: 1 Bosch PZ 12 HM 100/11 Einspritzpumpe für 12 Zyl."

"Lader: einstufiges Schleudergeblaese mit barometrischer regelung"

Originally Posted by MiG-3U

It's not a test, just a piece of paper, no test data nor kenblats of production planes support 500km/h at sealevel.

Nope. French trials for example with Bf 109E-3 WNr. 1304. (DB 601A-1, so lower power at 1,3ata) show 495 kph at about 500 meter altitude.

http://kurfurst.org/Performance_test...09EWNR1304.jpg

Everything else is around 460-470km/h including swiss planes with the 601Aa.

All figures match the V15a performance using Höhenlader well, indicating the tests

"Everything else", well.

WNr. 1774. 498 kph, E-1, "DB 601A", 1,35 ata. 1060 PS.
WNr. 1791. 475 kph, E-1, DB 601A-1, 1,3ata 990 PS, ie. 70 PS less power. "figures are not corrected for guaranteed engine output"
WNr. 1792. 467 kph, E-1 DB 601A-1, 1,3ata 990 PS, ie. 70 PS less power. "figures are extrapolated graphically to 0m" and "figures are not corrected for guaranteed engine output"
WNr. 1304, ca. 485 kph, E-3, DB 601A-1, 960 Hgmm (ca. 1,3 ata). 990 PS, ie. 70 PS less power. With estimated position error curves: +/- 15 kph on speed.
WNr. 2404, 464 kph, E-3, DB 601Aa, probably 1,35ata. Conditions unknown. Curves clearly show single speed supercharged performance with no appearant hydraulic curveture. Figures closely match WNr. 1774. Höhenlader performance (extrapolating to about 460 kph at SL)


Calculating the speed of the the Spitfire I at +12lbs the same way as done in the V15A report:

Density at sealevel: 1.225 kg/cubic meter
Power at sealevel at +6.25lbs: 880hp
Power at sealevel at +12lbs: 1180hp
Speed at sealevel at +6.25lbs: 280mph

r = ((1180/880)*(1.225/1.225))^(1/3) = 1.103

V0 = 280mph * 1.103 = 309mph = 497kmh

However, that is a crude, unaccurate and partially wrong way to calculate it.

The only speculative but logically correct part in my post is the size of the oil cooler, and it was there only because you asked it. The rest are facts.

As shown above, they are not facts but misrepresentation of the facts.

Your theory is basically this. Messerschmitt built a prototype for the Bf 109E series, which achieved around 500 kph with the the engine cowling still unpainted, without fuel injection and without a multi speed supercharger, which (then appearantly the Americans got hold somehow of another Bf 109E and oddly tested it the same way as the Germans theirs... ) . They have noted in their report that due to time constraints, they could not yet fit the proper exhausts and air intake, so "further increases in performance are possible".

Then they supposedly went on improving it with a oil cooler of the size of an elephant, that chopped down 40 kph (!!! ) from top speed, but strangely enough only at low altitude , they added direct fuel injection which probably made the engine even weaker. Happy of good days work, and that they achieved no less than 40 kph speed loss, they decided to put that new version into production. The legal and financial department went nuts too, and decided to give legal guarantees for reaching a performance that according to you, was impossible to achieve. Save for a few odd examples that landed in French, Swiss hands which matched V15a figures finely.

Extremely likely, yes.

Any observations on the "prototype" Bf 109E overlayed with the Swiss trials of WNr 2404?

[MiG-3U]

Originally Posted by Kurfürst

Nope.

DB 601A-0.

"Gemischung durch: 1 Bosch PZ 12 HM 100/11 Einspritzpumpe für 12 Zyl."

"Lader: einstufiges Schleudergeblaese mit barometrischer regelung"

Well, we have the test data of the V15a showing clearly a supercharger with two fixed speeds instead hydraulic clutch and this is supported by Von Gersdorf et.al. Any source can contain errors or projected things which happened later, this is why any source should be contested. In this case your source, what ever it is, is easily contested because the characters of the hydraulic clutch are not there and Von Gersdorf et.al. can be seen as more credible source (generally the secondary source is seen more credible because it's better contested and refined, like in wikipedia).

[Kurfürst]

Originally Posted by MiG-3U

Well, we have the test data of the V15a showing clearly a supercharger with two fixed speeds instead hydraulic clutch

So does this US trial of captured Bf 109E. Does it have "two fixed speeds instead hydraulic clutch"?



And so does this German trial of captured Bf 109G-6. Does it have "two fixed speeds instead hydraulic clutch"?



And so does this German trial of captured Bf 109G-14. Does it have "two fixed speeds instead hydraulic clutch"?

and this is supported by Von Gersdorf et.al.

I don't see "Von Gersdorf et.al." anywhere here. Only your speculations, which happen to be repeating the same as that of a certain figure called Harri Pihl. Who has also kept refusing posting his sources, when cornered.

[MiG-3U]

Originally Posted by Kurfürst

Fact: report says aircraft is identical to production E-1.

The E-1 was then still under developement and came out much later.

Originally Posted by Kurfürst

Erflogene Geschwindigkeit 493 km/h, auf Normaltag und Garantileistung umgerechnete Geschwindigkeit 498 km/h im 0 m.

They have flown 493kmh at altitude of 440m, which was not yet corrected for German Standard Day conditions or the Guaranteed output of the engine. Bench tests confirmed engine was developing 45 PS less than it should have.

No anykind mispresentation there, 485kmh at 0m can be read directly from the chart and calculation is based on density 1.175 kg/cubic meter.

Originally Posted by Kurfürst

Fact: Boden and Hohenlader are just generic names for MS and FS speeds, present on all DB 601/605/603.

These engines do not have gear change nor pressure drop until FTH. Only a altitude range where the supercharger speed is variable.

Regarding the rest, many organisations have done tests poorly or intrepeted tested data poorly. You just pick the ones which suit to your agenda.

Over and out until something relevant is posted.

[Osprey]

Originally Posted by Kurfürst

You want the original document, Osprey?

No need, just making the point. I am happy to liase with pstyle on it though, I would like to just make sure that the 109 is correct in HSFX, of course would seek necessary approval from 109 jockeys who have a similar historically accuracy first agenda to me.

[Osprey]

Originally Posted by Kurfürst

So does this US trial of captured Bf 109E. Does it have "two fixed speeds instead hydraulic clutch"?

Yes, but this one clearly doesn't make 500kmph on the deck (290mph or 464kmph) and has a maximum speed of 340mph (544kmph). That's about 15mph slower than the Spitfire top end and only 6 or so kmph faster than the Spitfire on the deck running at only 6.25lbs of boost. In fact, 290 mph is only slightly faster @ sea level than a Hurricane I @ 12lbs + 3000rpm.
Now, I'm not suggesting that the gap in speed between the Spitfire and 109 is that large, but it's certainly wildly different from your chart. Given that you stated that the prototype you quote is unchanged from the production E-1, how can you account for this discrepancy?

The trouble is, there's this whole 'big lie' about the 109 advantages on the Spitfire (you perpetuate it, that the 109 can out climb, out dive, out speed, out gun and out turn the Spitfire) Some of these are true or course, but not all like you indicate.

[Kurfürst]

Originally Posted by Osprey

No need, just making the point. I am happy to liase with pstyle on it though, I would like to just make sure that the 109 is correct in HSFX, of course would seek necessary approval from 109 jockeys who have a similar historically accuracy first agenda to me.

I can post the paper for you when I get home, though you have already seen it in full (transcribed) on my site. The Blatt 3 part pstyle was missing is actually there, its the 3rd page that covers the second part of point three and the rest of point four (the typed text part spread through multiple pages), but for reasons of convinience I have ommitted the header for the rest of the pages, which would break the text flow and would say just the same, well, except for "Blatt 3" instead of "Blatt 1" and "Blatt 2" in the right upper corner.

[Kurfürst]

Originally Posted by Osprey

Yes, but this one clearly doesn't make 500kmph on the deck (290mph or 464kmph) and has a maximum speed of 340mph (544kmph).

Nope, its just another 109 that has it's hydraulic supercharger set up to give fixed gear ratios. All it needs is to disable the second oil pump in the hydraulic clutch to get a fixed low gear, and then to set the second oil pump in the hydraulic clutch to get a fixed high gear (at minimum slip). Looking at the other testing papers, it was commonly done to reduce the margin of error in the measurements.

BTW if you look at the paper carefully you will see that no low level speed measurement was made, the lowest actual data point measured in low gear was 336 mph at 12k feet. Anything below was simply extrapolated (and obviously with a large margin of error, given the very few points available for extrapolation)

That's about 15mph slower than the Spitfire top end and only 6 or so kmph faster than the Spitfire on the deck running at only 6.25lbs of boost. In fact, 290 mph is only slightly faster @ sea level than a Hurricane I @ 12lbs + 3000rpm.
Now, I'm not suggesting that the gap in speed between the Spitfire and 109 is that large, but it's certainly wildly different from your chart. Given that you stated that the prototype you quote is unchanged from the production E-1, how can you account for this discrepancy?

Well for one we have absolutely no idea about the testing conditions. Without these, it's rather pointless to compare different tests. The aircraft does show very different results from the rest, which can mean the testing conditions may have been different, the airframe or engine was subpar and so on. What "109" is this anyway?

The trouble is, there's this whole 'big lie' about the 109 advantages on the Spitfire (you perpetuate it, that the 109 can out climb, out dive, out speed, out gun and out turn the Spitfire) Some of these are true or course, but not all like you indicate.

I don't perpetuate that. Especially, since much of this data, for example climb rates are missing for both aircraft.

[pstyle]

Originally Posted by Kurfürst

The Blatt 3 part pstyle was missing is actually there, its the 3rd page that covers the second part of point three and the rest of point four (the typed text part spread through multiple pages), but for reasons of convinience I have ommitted the header for the rest of the pages, which would break the text flow and would say just the same, well, except for "Blatt 3" instead of "Blatt 1" and "Blatt 2" in the right upper corner.

cheers Kurfurst.

[Al Schlageter]

Can someone tell why these 2 German documents have the Vo as 476-476kph and 466-467kph.