Bf109G-2 underperforms at altitude

[III/JG2Gustav05]

Since i had some time to waste

 

Screenshot 2015-12-04 21.38.45.png

All done with automatic radiator and on the autumn map and calculated by flying 40 km and then calculation time used for this.

 

 

Also did one (first try) climb test (only comparing from 1000-6000 m, because i'm too lazy to time the speed right to make the 0-1000 m get correct and because it was becoming boring at 6000 m).

Again with automatic radiator, didn't have any trouble with overheating engine.

 

Screenshot 2015-12-04 21.38.21.png

 

(compared to the G-1 source posted above)

 

And btw, there's no way you would've reached this speed in the previous update with automatic radiators, thanks to the wrong thermostat temperature used before.

In summer map109's top speed drops about 3kph IAS due to radiator wider openning caused by hot temperature.

[Holtzauge]

You can not fully rely on the power weight ratio for climb performance assessment, radiator position, tailwheel setting etc also impact it greatly.

 

True, the tailwheel will affect the performance. However, the effect is greatest at top speed and at climb speed you would not see such a big impact. Concerning the radiator position, this was also discussed in the thread I linked . Anyway, the radiator position is an effect on all Me-109's so I don't see how this could be used to explain the G2 climbing better than the other 109's at a given P/W ratio?

[6./ZG26_Klaus_Mann]

The german test data for the G-1 source used for the climb rate was achieved with almost closed radiator settings, while the ERLA numbers for the early G-1 were for 50% radiator settings (18.5m/s and 5:42 to 6000m opened rads)  However the Rechlin numbers differ (21m/s and 5:14 from a Rechlin Test with radiators in a smaller position).

The Machines are the same except landing gear assembly, which was the late one for the Machine tested at Rechlin, and slower by 12kph.

 

Please keep in mind the radiator settings and all times and compare only the correct radiator settings to the correct Reference. The Top Speeds given in both the ERLA and Rechlin Reference are understood for Schnellflugstellung, or smallest opening.

 

-The Rechlin Reference is irrelevant for Top Speed since it was performed on a machine with the late landing gear type, however the given rate of climb should be reference for us when flying with manually closed radiators

-The Erla reference is the main one we should rely on for Top Speed, however rate of climb was tested rather gingerly for reasons of engine preservation. It is probably the lowest RoC achievable with a G-2 at Combat Power.

 

Should you compare speeds with references remember:

Manual radiators 5%

Trim fully nose down

Full throttle

for the speed run.

Edited December 6, 2015 by 6./ZG26_Klaus_Mann

[Holtzauge]

The german test data for the G-1 source used for the climb rate was achieved with almost closed radiator settings, while the ERLA numbers for the early G-1 were for 50% radiator settings (18.5m/s and 5:42 to 6000m opened rads)  However the Rechlin numbers differ (21m/s and 5:14 from a Rechlin Test with radiators in a smaller position).

The Machines are the same except landing gear assembly, which was the late one for the Machine tested at Rechlin, and slower by 12kph.

 

Please keep in mind the radiator settings and all times and compare only the correct radiator settings to the correct Reference. The Top Speeds given in both the ERLA and Rechlin Reference are understood for Schnellflugstellung, or smallest opening.

 

-The Rechlin Reference is irrelevant for Top Speed since it was performed on a machine with the late landing gear type, however the given rate of climb should be reference for us when flying with manually closed radiators

-The Erla reference is the main one we should rely on for Top Speed, however rate of climb was tested rather gingerly for reasons of engine preservation. It is probably the lowest RoC achievable with a G-2 at Combat Power.

 

Should you compare speeds with references remember:

Manual radiators 5%

Trim fully nose down

Full throttle

for the speed run.

I agree that the radiator position does have an impact but AFAIK this is in the order of 1 m/s between fully open and fully closed. Also, there are a number of different climb estimates (17-24 m/s) for the G2 as I referenced in the thread I linked to and I don't see what exactly makes 21 m/s the best estimate? In addition, why should the G2 climb so much better than the F4 given that the difference in P/W ratio is so small?

[Reflected]

Since i had some time to waste

 

Screenshot 2015-12-04 21.38.45.png

All done with automatic radiator and on the autumn map and calculated by flying 40 km and then calculation time used for this.

 

 

Also did one (first try) climb test (only comparing from 1000-6000 m, because i'm too lazy to time the speed right to make the 0-1000 m get correct and because it was becoming boring at 6000 m).

Again with automatic radiator, didn't have any trouble with overheating engine.

 

Screenshot 2015-12-04 21.38.21.png

 

(compared to the G-1 source posted above)

 

And btw, there's no way you would've reached this speed in the previous update with automatic radiators, thanks to the wrong thermostat temperature used before.

 

Matt, I checked the website, and the test you are comparing our G-2 to was performed with a fixed tailwheel 109, resulting in a 12kph speed loss.

 

 

 

 Trials at E-Stelle Rechlin on a Bf 109G-1 - the results were later becoming the official specifications for the type in a Kennblatt issued on 8 March 1943 - resulted in 650 kph at 6400m; the tested aircraft appearantly had a fixed tailwheel resulting 12 km/h speed loss, which needs to be taken account.

 

    Soviet performance trials at the NII VVS with a captured Bf 109G-2,  Werknummer 14 513 are in remarkably good agreement with the Messerschmitt datasheet below : 666 kph was achieved at 7000m altitude. This aircraft's tailwheel was semi-retractable and thus the results are directly comparable to the Messerschmitt datasheet below.

[6./ZG26_Klaus_Mann]

I agree that the radiator position does have an impact but AFAIK this is in the order of 1 m/s between fully open and fully closed. Also, there are a number of different climb estimates (17-24 m/s) for the G2 as I referenced in the thread I linked to and I don't see what exactly makes 21 m/s the best estimate? In addition, why should the G2 climb so much better than the F4 given that the difference in P/W ratio is so small?

Well:

Finnish Test: Non Retractable Tailwheel as well as faults in the Kommanodgerät and the finnish performed their tests differently, with higher IAS, which at 2000m lead to a considerable Spike, but lower rates of climb above 3000m. This test has the 24m/s.

 

ERLA: Retractable Tailwheel. This test was performed with half open radiators, resulting in a maximum rate of climb of 18.5m/s and higher time to altitude

This model has the valid top speed for our model of 535 at SL anmd 660 at 7000m

Temperatures were kept at 85°C

 

Rechlin Test: Non Retractable Tailwheel, small radiator settings, resulting in higher Coolant Temperatures and 21m/s

 

Biriths Trials: Tropicalized Version, Air filters and stuck Oil Radiators. Lower Power Output and different Kommandogerät settings resulting in considerably lower rates of climb

 

Soviet Trials: Really just agree with Rechlin, 21m/s and 660kph.

[Matt]

 

 

Matt, I checked the website, and the test you are comparing our G-2 to was performed with a fixed tailwheel 109, resulting in a 12kph speed loss.

 

It apparently had a fixed tailwheel, even though i've not seen that mentioned anywhere apart from Kurfürst website. 

 

However, you should have no trouble squeezing out a bit of speed by using manual radiators in BoS and at high altitude (which this topic is about), the speeds are almost identical anyway (in fact, at 10 km the fixed tail wheel seems to add speed for some reason...).

 

In any case, i'll not redo my tests with manual radiators, because i'm busy testing something else now.

[6./ZG26_Klaus_Mann]

 

It apparently had a fixed tailwheel, even though i've not seen that mentioned anywhere apart from Kurfürst website. 

 

However, you should have no trouble squeezing out a bit of speed by using manual radiators in BoS and at high altitude (which this topic is about), the speeds are almost identical anyway (in fact, at 10 km the fixed tail wheel seems to add speed for some reason...).

 

In any case, i'll not redo my tests with manual radiators, because i'm busy testing something else now.

 

ERLA (the 660kph) were performed May 1942, the Second Rechlin test in 1943, well after the large gear assembly was introduced.

[Matt]

That's fine, still the speed at high altitude is almost the same in both sources and according to my test (with auto radiator) it's faster at 5000 meters and above than that source anyway. So it will not be slower with fixed radiators and i don't think you're saying here, that the speed is too high at altitude and you want them to tone it down. Or maybe i misunderstood this topic.

[Reflected]

 

ERLA: Retractable Tailwheel. This test was performed with half open radiators, resulting in a maximum rate of climb of 18.5m/s and higher time to altitude

This model has the valid top speed for our model of 535 at SL anmd 660 at 7000m

Temperatures were kept at 85°C

 

 

Can you please point me towards the source of this? That says both he date, the temperature, and the tailwheel? I might run a test then, and if the discrepancy is big, I'll present it.

[6./ZG26_Klaus_Mann]

That's fine, still the speed at high altitude is almost the same in both sources and according to my test (with auto radiator) it's faster at 5000 meters and above than that source anyway. So it will not be slower with fixed radiators and i don't think you're saying here, that the speed is too high at altitude and you want them to tone it down. Or maybe i misunderstood this topic.

???

G-2 IRL ERLA/Rechlin

0: 537/525

2k:583/563

4k:624/602

6k:647/642

7k:660/649

 

G-2 Ingame (5% rads)

0:535

2k:579 (528IAS)

4k:609 (505IAS)

6k:641 (480IAS)

7k: 642 (456IAS)

 

The G-2 Performance drops from one Reference to another.

Someone make this a chart. I'll try as well.

[6./ZG26_Klaus_Mann]

I can't reverse the Axis for the Life of it.

 

Hope you get my point.

Edited December 6, 2015 by 6./ZG26_Klaus_Mann

[III/JG2Gustav05]

I agree that the radiator position does have an impact but AFAIK this is in the order of 1 m/s between fully open and fully closed. Also, there are a number of different climb estimates (17-24 m/s) for the G2 as I referenced in the thread I linked to and I don't see what exactly makes 21 m/s the best estimate? In addition, why should the G2 climb so much better than the F4 given that the difference in P/W ratio is so small?

according to the report 360 mm opening can decrease1m/S climb speed at sea level and 2m/s at altitude comparing to 180mm opening. not as you mentioned its fully closed and fully opened.

True, the tailwheel will affect the performance. However, the effect is greatest at top speed and at climb speed you would not see such a big impact. Concerning the radiator position, this was also discussed in the thread I linked . Anyway, the radiator position is an effect on all Me-109's so I don't see how this could be used to explain the G2 climbing better than the other 109's at a given P/W ratio?

As I remembered DB605 can sustain higher coolant temperature than DB601, I think this is one of the explanation.

 

It apparently had a fixed tailwheel, even though i've not seen that mentioned anywhere apart from Kurfürst website. 

 

However, you should have no trouble squeezing out a bit of speed by using manual radiators in BoS and at high altitude (which this topic is about), the speeds are almost identical anyway (in fact, at 10 km the fixed tail wheel seems to add speed for some reason...).

 

In any case, i'll not redo my tests with manual radiators, because i'm busy testing something else now.

 

manual radiator will not create big speed difference anymore after 1.105. for G2 seems only 2kp/h.

[Matt]

???

G-2 IRL ERLA/Rechlin

0: 537/525

2k:583/563

4k:624/602

6k:647/642

7k:660/649

 

G-2 Ingame (5% rads)

0:535

2k:579 (528IAS)

4k:609 (505IAS)

6k:641 (480IAS)

7k: 642 (456IAS)

 

The G-2 Performance drops from one Reference to another.

Someone make this a chart. I'll try as well.

I wasn't comparing it to your IAS numbers (not sure why you're using those to compare them to the sources, because it's way too inaccurate to calculate that), but to my test results with automatic radiator.

 

For what it's worth, i now again tested 7 km altitude with manually adjusted radiators and i get exactly 656 km/h. So it's 4 km/h too slow at that altitude, big deal, especially considering that in my test with automatic radiators, it's actually 3 km/h too fast at 6 km.

Edited December 6, 2015 by Matt

[III/JG2Gustav05]

Bf109 Speed.JPG

I can't reverse the Axis for the Life of it.

 

Hope you get my point.

Hi Klaus, did you use trim the elevator to 100%? you have to trim it to 100% to get the max speed.

[6./ZG26_Klaus_Mann]

I wasn't comparing it to your IAS numbers (not sure why you're using those to compare them to the sources, because it's way too inaccurate to calculate that), but to my test results with automatic radiator.

 

For what it's worth, i now again tested 7 km altitude with manually adjusted radiators and i get exactly 656 km/h. So it's 4 km/h too slow at that altitude, big deal, especially considering that in my test with automatic radiators, it's actually 3 km/h too fast at 6 km.

Give me your IAS please.

Hi Klaus, did you use trim the elevator to 100%? you have to trim it to 100% to get the max speed.

Yes I do.

[III/JG2Gustav05]

Give me your IAS please.

Yes I do.

I did a quick test @7k in autum map I get 452 kph IAS with autorad. at same time by using distance divided by time method I get 655kph.

[6./ZG26_Klaus_Mann]

Bringing up the question of Equivalent Air Speed and Calibrated again. The only way I get any of your results is by using the IAS we have as Equivalent.

However the IAS we have on the HUD at lest is Calibrated.

The Hud would have to be corrected for Compressibility, which it isn't.

[Matt]

Give me your IAS please.

I've not even looked at the IAS during my tests, so i couldn't tell you.

[6./ZG26_Klaus_Mann]

I don't know on whose side the error is. I go mainly by the IAS I achieve inflight, however none of the conversions make sense except the Equivalent Airspeed, which I don't think was installed on any Aircraft of the Time, since it already corrects for compressibility, while the Calibrated Airspeed is closest to IAS in Real Life, but results turn out too low, or in a weird graph like the one above.

If I enter the IAS I get as Equivalent, all results turn out well and closest to correct, however, Calibrated turns out to be too low.

 

I'd be willing to concede now that most likely it's not the Bf109G-2 that is off, but the HUD and or the ASI, for showing EAS instead of actual IAS or CAS.

[Kurfurst]

Since i had some time to waste

 

Screenshot 2015-12-04 21.38.45.png

All done with automatic radiator and on the autumn map and calculated by flying 40 km and then calculation time used for this.

 

 

Also did one (first try) climb test (only comparing from 1000-6000 m, because i'm too lazy to time the speed right to make the 0-1000 m get correct and because it was becoming boring at 6000 m).

Again with automatic radiator, didn't have any trouble with overheating engine.

 

Screenshot 2015-12-04 21.38.21.png

 

(compared to the G-1 source posted above)

 

And btw, there's no way you would've reached this speed in the previous update with automatic radiators, thanks to the wrong thermostat temperature used before.

 

Looks like the current BoS FM model is pretty good match with historical sources. Thank you for putting effort into the testing!

[6./ZG26_Klaus_Mann]

Looks like the current BoS FM model is pretty good match with historical sources. Thank you for putting effort into the testing!

It's what I do.

[III/JG2Gustav05]

Well:

Finnish Test: Non Retractable Tailwheel as well as faults in the Kommanodgerät and the finnish performed their tests differently, with higher IAS, which at 2000m lead to a considerable Spike, but lower rates of climb above 3000m. This test has the 24m/s.

 

ERLA: Retractable Tailwheel. This test was performed with half open radiators, resulting in a maximum rate of climb of 18.5m/s and higher time to altitude

This model has the valid top speed for our model of 535 at SL anmd 660 at 7000m

Temperatures were kept at 85°C

 

Rechlin Test: Non Retractable Tailwheel, small radiator settings, resulting in higher Coolant Temperatures and 21m/s

 

Biriths Trials: Tropicalized Version, Air filters and stuck Oil Radiators. Lower Power Output and different Kommandogerät settings resulting in considerably lower rates of climb

 

Soviet Trials: Really just agree with Rechlin, 21m/s and 660kph.

Hello Klaus,

I went through Kurfust's website and could not find any description about the radiator setting in Rechlin test,  could you tell me where I can find the information? Thanks!

[III/JG2Gustav05]

Concerning the G2 climb rate, there was a long discussion on this some time ago: http://forum.il2sturmovik.com/topic/6830-bf-109-g-2-climb-data/?do=findComment&comment=122853

 

At that time the BoS G2 was climbing at around 24 m/s IIRC. So if it is now doing 21 m/s that is a huge improvement but still on the high side I think. A more realistic figure (as outlined in the link) would be in the order of 19 m/s IMHO.

 

OTOH while absolute values of course are important, an even more important aspect is the relative climb rates and if the Russian birds are optimistic by a similar margin then I guess 21 m/s is close enough.

Klaus test shows that it's currently 18.5m/s, You should be very satisfied with it.

Edited January 6, 2016 by III/JG2Gustav05

[6./ZG26_Klaus_Mann]

Klaus test shows that it's currently 18.5m/s, You should be very satisfied with it.

In fact, yes, on Auto Rads it behaves correctly, however smaller settings should result in greater rates of climb. Right now 19.5-20m/s can be achieved with smaller settings. But we should be getting 21m/s at some settings.

[Holtzauge]

Klaus test shows that it's currently 18.5m/s, You should be very satisfied with it.

Since this seems to be closer to a historical climbrate then surely everybody should be happy?

 

Jokes aside, while absolute climbrates are important, IMHO in a sim like this the relative numbers are even more important and from the Fw-190A3 climb time discussion it seems the A3 is on the low side while the Yak-1 is on the high side so really what is important is to get these number right in relation to each other. If they all are translated up or down one or two m/s is less important. However right now it looks like the A3 is ca 2 m/s on the low side and the Yak-1 maybe 1 m/s or more on the high side.

[III/JG2Gustav05]

In fact, yes, on Auto Rads it behaves correctly, however smaller settings should result in greater rates of climb. Right now 19.5-20m/s can be achieved with smaller settings. But we should be getting 21m/s at some settings.

that leads me back to the original question I cannot find any description about the radiator setting in this 21m/s - Rechlin test report, where can I find the information? Another thing I am curious with, does engine get overheat in this rechlin test which as you mentioned was done with smaller radiator setting? Seems we cannot acheive similar result in our game without engine damaged.

Edited January 6, 2016 by III/JG2Gustav05

[6./ZG26_Klaus_Mann]

This is from the May 1942 Erla Tests:

 

Steiglfug: Von 0 m bis VH Kühler halb geöffnet (nach bisheri-
gen Kühlermesslflügen erscheint dies etwas zu ungünstig, wird
aber bis zur Durchführung von Kühlerflügen mit Me 109 G 
zur Sicherheit beibehalten).

ab VH bis GH zur Rechnungvereinfachung statiger Übergang 
von Klappenstellung: halboffen auf Schnellflugstellung an-
genommen. (In wirklichkeit wird, je nach Motor, die Schnell-
flugstellung schon ca 2500 - 3000 m über VH erreicht).

 

Translated:

"Climb: From 0m to Critical Altitude Radiators 50% opened (already performed tests of the radiators concluded this to be disadvatntegeous, but for reasons of safety will be continued anyway).

 

From Critical Altitude to Service Ceiling uniform closing of radiators will be assumed from 50% opening to Quick Flight Setting. 

(In Reality, depending on engine, Quick Flight Settings are achieved just 2500-3000 above Critical altitude)."

 

This is the reason I think the radiators right now open too far. The Curve the radiators are set on, probably is for 80-90°C Thermostat, but open as if it were 103°C. 

So when before the rads were Over Performing, now they Underperform. The radiators should open probably 15-25% in a climb at 280kph, not 50% as they are right now,

The reason the openings can get so large in the first place is the fact that they draw from flowing air exclusively and tend to overheat on the ground. But in the air they were extremely efficient. 

[L3Pl4K]

This is from the May 1942 Erla Tests:

 

Steiglfug: Von 0 m bis VH Kühler halb geöffnet (nach bisheri-

gen Kühlermesslflügen erscheint dies etwas zu ungünstig, wird

aber bis zur Durchführung von Kühlerflügen mit Me 109 G 

zur Sicherheit beibehalten).

 

ab VH bis GH zur Rechnungvereinfachung statiger Übergang 

von Klappenstellung: halboffen auf Schnellflugstellung an-

genommen. (In wirklichkeit wird, je nach Motor, die Schnell-

flugstellung schon ca 2500 - 3000 m über VH erreicht).

 

Translated:

"Climb: From 0m to Critical Altitude Radiators 50% opened (already performed tests of the radiators concluded this to be disadvatntegeous, but for reasons of safety will be continued anyway).

 

From Critical Altitude to Service Ceiling uniform closing of radiators will be assumed from 50% opening to Quick Flight Setting. 

(In Reality, depending on engine, Quick Flight Settings are achieved just 2500-3000 above Critical altitude)."

 

This is the reason I think the radiators right now open too far. The Curve the radiators are set on, probably is for 80-90°C Thermostat, but open as if it were 103°C. 

So when before the rads were Over Performing, now they Underperform. The radiators should open probably 15-25% in a climb at 280kph, not 50% as they are right now,

The reason the openings can get so large in the first place is the fact that they draw from flowing air exclusively and tend to overheat on the ground. But in the air they were extremely efficient. 

Please send this to han.

[Kurfurst]

Could you post a picture of the orginal sheet in this forum please.

 

Will check when I access it. This is the May 1942 Mtt calculations for G-1, right? The note about radiator standards are present there also, but also in other papers. The May 1942 is barely readable though (as a matter of interest, there is also projection for G-1 with various improvements and full rating, top speed being IIRC 737 km/h

 

Though I do not get the fixation with it, operation of the radiators are seen very well and the same way as described in this September 1942 test on my site.

 

http://kurfurst.org/Performance_tests/109G1_messung601e605a/messung109g601e605a.html

 

Edited January 11, 2016 by VO101Kurfurst

[L3Pl4K]

 

 

Will check when I access it. This is the May 1942 Mtt calculations for G-1, right? The note about radiator standards are present there also, but also in other papers. The May 1942 is barely readable though (as a matter of interest, there is also projection for G-1 with various improvements and full rating, top speed being IIRC 737 km/h

Yes the may 42 Erla Test, thanks for your effort

[6./ZG26_Klaus_Mann]

Well, right now the G-2 climbs with 50% radiator opening and in a straight line at roughly 30% when controlled by Thermostat. Can I assume correctly that these settings are too large and that there is an error in the modelling of radiators?

[Guest deleted@50488]

Some charts in this thread show data for 11 and even 12 km alt.

 

I can barely climb and fly past 9km in il-2's G2 ....

 

Any of you successfuly flying at those top alts ? 12km ? 11 km ?

[3./JG15_Hans]

I heard the G2 could reach 1.4ATA in real life.

Is it true?

[JtD]

Yes, but at the end of 1942 (Battle of Stalingrad time) the DB605 engine was limited to 1.3ata.

[Kurfurst]

Yes, but at the end of 1942 (Battle of Stalingrad time) the DB605 engine was limited to 1.3ata.

 

There are several sources clearly stating the 1,3ata limitations were no longer present in that said time frame and the full 1,42 ata rating was cleared (although no doubt prematurely as subsequent docs from spring 1943 mention the limit again) for use.

[6./ZG26_Klaus_Mann]

There are several sources clearly stating the 1,3ata limitations were no longer present in that said time frame and the full 1,42 ata rating was cleared (although no doubt prematurely as subsequent docs from spring 1943 mention the limit again) for use.

The First Manual I have seen without Limitation is August 1943. And I think ingame it has no real negative consequences as the G-2 is still the fastest Aircraft, and the best Climber. 

If we get an Installment for the Second Half of 1943 we will most likely get G-4s and G-6s without the Limitations BUT with the late type Gear, so Speedwise the changes will be marginal, higher at WEP, lower in cont and Rate of Climb will be phenomenally good. 

[Kurfurst]

I am not arguing for an 1,42ata G-2 (which would be a total beast IMO) just mentioning that some docs (such as the November 1942 DB 605A Motorenhandbuch and British reports on the captured desert G-2/trop) suggests that there was temporary period coinciding the Stalingrad operations when the clearance was given out.

[6./ZG26_Klaus_Mann]

I am not arguing for an 1,42ata G-2 (which would be a total beast IMO) just mentioning that some docs (such as the November 1942 DB 605A Motorenhandbuch and British reports on the captured desert G-2/trop) suggests that there was temporary period coinciding the Stalingrad operations when the clearance was given out.

Which is at the same Level of Importance as P-40s running nothing but 70" all their lives. Maybe, but with a major pinch of Salt. 

[JtD]

There are several sources clearly stating the 1,3ata limitations were no longer present in that said time frame and the full 1,42 ata rating was cleared (although no doubt prematurely as subsequent docs from spring 1943 mention the limit again) for use.

But then there are also sources valid that state 1.3 was still in place and my summary is related to what the developers decided to put in game.