FW190 FM Change

[JtD]

Thanks for going the length to do the testing and preparing the results in an attractive way.

It appears that compared to real life procedures for the 109, the 109 is totally off the mark, the 190 being more reasonable. We get a glide ratio of ~1/3 for the 109 and ~1/5 for the 190.

[badatflyski]

start-Notleistung= emergency combat power (1/42ATA)
steig/kampfleistung= climb/continous max power (1/32ATA)

now about the REAL boost on A5 and forward:

The following text has been copied from a private Forum several years ago but it seems i fracked up the file and only have a part of the whole text.
Source

801D boost or C3-Einspritzung
Increasing Knock Limited Performance in the BMW801D2
Part 1
Throughout the war, the BMW801D2 was continually developed to keep
pace with the performance of the allied fighters faced by the FW-190
equipped Geschwaders. The engine became a reliable workhorse and made
the FW-190 one of the best performing low altitude fighters of the war.
It began its design lifecycle with a top shaft output of 1670PS at
Start u Notleistung at 1st Gear supercharger full throttle height and
gained 150 PS by wars end at the same settings. Additional boost systems
raised this power output to over 2100PS. The BMW801D2 was developed to
the limits of its potential and even beyond a point when other motors
such as the BMW802 showed greater promise for a similar effort.
The Achilles heel however continued to be high altitude performance.
This article in two parts will discuss the 4 major systems used to
increase knock-limited performance in the BMW801D2 above the engines
normal Start u Notleistung rating.
---------------------------------------------------------------------------
In June of 1942 BMW completed a theoretical investigation in the potential
development of the motor. Without any major change to the motor it was
possible to increase shaft power output at full throttle height by 40PS
at Start u Notleistung and 110PS at Steig u Kampfleistung. With some major
changes it was possible to get a shaft output of 2000PS without additional
knock limiting performance enhancements. It was determined that the motor
had the potential for developing between 2000PS-2200PS by injection of
knock limiting agents such as water or alcohol water mixtures.
Work began immediately on putting the theory into practice.
Prototype motors were constructed and work began on improving the power
output of the motor at all levels. By July 1942 BMW had constructed several
prototype motors to begin laboratory bench testing. BMW801D2V15 achieved
1950PS shaft output without ram or knock limiting performance enhancements
during this phase. In the quest for attaining the full potential of the
BMW801D2 three knock limiting agent injection systems and one method of
oxygen enrichment of the charge were shown to be practical or worthy of
further investigation.
----------------------------------------------------------------------------
C3-Einspritzung, The Bomber and Attack Pilots Insurance
The first system to see operational adoption was the injection of C3 fuel
as a knock limiting agent directly into the left side of the supercharger
intake.
Motors were modified with stronger pistons adopted from the BMW801E/S
development. These new pistons became the production standard on all
BMW801D series motors in June 1943.

On the 10th of April 1943 the first flight testing of the new system began
with a 25-minute flight in the low altitude portion of the 1st gear
supercharger and resulted in 8 minutes of the systems use.
By the 22nd of April 1943 test flights were using the system as long as 15
minutes and at manifold pressures as high as 1.8ata between 3.5km and
7km altitude.
Initial flight-testing was completed on the 17th of May 1943.
The flight test results concluded however that the system produced 2050PS
in the 1st Gear Supercharger and that a manifold pressure of 1.65ata could
be used reliably. As the pressure fell off with altitude however,
the standard fuel pump was not able to provide sufficient quantities of fuel
to allow the system to develop additional power in the 2nd Gear Supercharger.
The engine cooling was also not sufficient enough for the system to be used in
climbing flight. The fuel pump could not deliver enough fuel to the left hand
supercharger intake to keep cylinder temperatures within operational limits at
climbing speeds. It was felt that a further 50PS of thrust power could be
gained by changing the propeller reduction gearing to a more suitable ratio
in order to fully exploit the new power gains of the motor. The initial
testing was completed and the findings compiled by the 19th of July 1943.
It is interesting to note that JG54 begins reporting experience with the
new system in 23 July 1943. This point..(text missing)



So, there are actually 2 different versions
Phase1: Low alt 1.58ATA (1000m max with standard fuel-pump) from june43 to end 43
Phase2: Full 1.65ATA on both Charger's gears from End 43.
And this system was as it seems used on all versions afterwards

[Nicholaiovitch]

Originally Posted by JtD

Thanks for going the length to do the testing and preparing the results in an attractive way.

It appears that compared to real life procedures for the 109, the 109 is totally off the mark, the 190 being more reasonable. We get a glide ratio of ~1/3 for the 109 and ~1/5 for the 190.

Tests of Glide ratio (clean) of the BF109G2 are well within published criteria.

- Stable flight, 260-270kph (best L/D speed), radiator closed, engine "Off" gives 1minute 42sec to lose 1000m (same conditions as in previous test)

- This gives the Bf109G2 FM a glide ratio of 12.78:1 (as published on the net)

- Test of the Fw190A4 with 4.11 FM (same L/D speed quoted) and same conditions gives 1minute 56sec to lose 1000m.

- This gives the Fw190A4 new FM a glide ratio of 16.52:1.......Is that correct?

Nicholaiovitch

[JtD]

Wait - 270 km/h = 75m/s.
Bf 109 - 102 seconds to lose 1000m - 7650m distance / 1000m altitude = 7.7
Fw 190 - 116 seconds to lose 1000m - 8700m distance / 1000m altitude = 8.7

You had me scared there for a minute, 16.5 would be way too high. Even 12.8 sound like a very good figure for a plane like the 109.

[Nicholaiovitch]

Originally Posted by JtD

Wait - 270 km/h = 75m/s.
Bf 109 - 102 seconds to lose 1000m - 7650m distance / 1000m altitude = 7.7
Fw 190 - 116 seconds to lose 1000m - 8700m distance / 1000m altitude = 8.7

You had me scared there for a minute, 16.5 would be way too high. Even 12.8 sound like a very good figure for a plane like the 109.

Oops....sorry JtD...I was still calculating ROD and got my sums mixed up....however....have a look at this:-

http://www.adlerhorst-hangar.com/emil-91.html

Nicholaiovitch

[JtD]

Certainly an interesting account. Messerschmitt polars for the 109 E show a optimum L/D of about 10, at a Cl of around 0.5. I'm more inclined to stick with that figure than with Bob's. Focke Wulf gives L/D max of around 11 for the Fw 190A. Unfortunately I couldn't find polars for the flaps down configuration.

Both figures show a bit of a variance, so +- 1 is easily possible, but at any rate, I guess we can agree that the in game glide ratio as measured by you is (way) too low. I'll try to do my own test soon and will see if I can confirm your findings, it might help to reduce speed a bit.

[JtD]

Basically I can confirm your findings. I'm getting the 109 to about 1:8, the 190 to about 1:9. I think one difference between the real plane and the in game representation is the lack of a fully featherable propeller, this could improve glide ratio quite a bit.

Anyway, what does it tell us about the realism of the landing characteristics, or more specifically the glide characteristics with flaps and gear down? Personally I see no reason to consider the STOL characteristics of the 109 more realistic than the 4.11 190.

[Nicholaiovitch]

Originally Posted by JtD

Basically I can confirm your findings. I'm getting the 109 to about 1:8, the 190 to about 1:9. I think one difference between the real plane and the in game representation is the lack of a fully featherable propeller, this could improve glide ratio quite a bit.

Anyway, what does it tell us about the realism of the landing characteristics, or more specifically the glide characteristics with flaps and gear down? Personally I see no reason to consider the STOL characteristics of the 109 more realistic than the 4.11 190.

Your point about the fully featherable prop. not being available in game is a very worthy comment. (wish it was!)

There are other reports of glide ratios being as high as 1:12 for the Bf109, but thinking about it, all these reports were from BoB pilots attempting to glide across the Channel after engine problems. This would have meant heading SE and with the prevailing wind being from the west in UK, it is conceivable that a tail wind (especially from 4000m as quoted) would have given the impression of a superior glide performance.

It has been an interesting exercise flying these profiles and the conclusions are more or less what has been stated already:-

- The deceleration characteristics of the FW190 with the new FM from speeds above 400Kph to circuit speeds is heavily influenced by the prop behaviour in auto pitch.
- By ensuring radiator is fully open before decelerating and additionally selecting manual pitch (set 100%), the deceleration rate can be very considerably reduced.
- Descent rates (at idle and/or engine shut down)in the landing config. may/may not be truly realistic as no information seems available.

Nicholaiovitch