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NN_Tym
09-18-2004, 02:20 AM
Hi all,

I would like to know which documents are used to set the climbrate of the Bf109G2 in the present version of AEP.

I have a lot of curves on my HD. I don't know where I got them. They give widely different numbers, and I would like to know if someone can tell me where to find the curves actually used in AEP.

For example, I have several tests of Bf109G1 made by the Germans, and a test of a Bf109G2 made by the Finns.

The Finns get a vertical speed that increases from 0m (20,8m/s) to 1800m (24,4m/s).

While the German get a constant vertical speed from 0m to 2000m (21m/s).Both tests use 1.3 ATA.

I have a third document that gives three different curves. But I guess these are not measured climbrates but calculated ones. The title is :
"Steiggeschwindikeit
gerechnet Mit.AG erfragen Erla Maschinwerk"
dated 3.4.43

I see three curves on this one, and cannot find out what they represent, as some words are difficult to decipher from the document.

The results are too different not to be disturbing.

Can someone help me understand those curves, and why the differ so much.

NN_Tym
09-18-2004, 02:20 AM
Hi all,

I would like to know which documents are used to set the climbrate of the Bf109G2 in the present version of AEP.

I have a lot of curves on my HD. I don't know where I got them. They give widely different numbers, and I would like to know if someone can tell me where to find the curves actually used in AEP.

For example, I have several tests of Bf109G1 made by the Germans, and a test of a Bf109G2 made by the Finns.

The Finns get a vertical speed that increases from 0m (20,8m/s) to 1800m (24,4m/s).

While the German get a constant vertical speed from 0m to 2000m (21m/s).Both tests use 1.3 ATA.

I have a third document that gives three different curves. But I guess these are not measured climbrates but calculated ones. The title is :
"Steiggeschwindikeit
gerechnet Mit.AG erfragen Erla Maschinwerk"
dated 3.4.43

I see three curves on this one, and cannot find out what they represent, as some words are difficult to decipher from the document.

The results are too different not to be disturbing.

Can someone help me understand those curves, and why the differ so much.

NN_Tym
09-18-2004, 02:50 AM
Just to make my message clearer... I KNOW there were other threads about the same subject (I even posted in them).

Now, I would like to learn more about the three aformentionned documents. Why so much difference ? Method of testing ? Quality of fuel ?

If you look at the Finnish test, it seems the plane is just a combat ready one, with nothing special. Yet the results are way over results from German sources. There must be a reason. I hope someone found out the reason since the last such thread.

For the third document (about Erla), I would like to know what each curve represents. As, if I recall correctly, Butch2K was the first to post it, I guess he knows what each curve is all about.

Thanks for any enlightment.

Fehler
09-18-2004, 03:04 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by NN_Tym:
look at the Finnish test, it seems the plane is just a combat ready one, with nothing special. Yet the results are way over results from German sources. There must be a reason. I hope someone found out the reason since the last such thread.<HR></BLOCKQUOTE>

The Fins were using a speedhack. http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

But seriously, I bet if you EMailed Butch2k he would be glad to enlighten you on what results mean what.

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p1ngu666
09-18-2004, 07:08 AM
maybe the finns ran with the radiators more closed due to winter being DAMN cold there?
just guessin tho http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif

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hop2002
09-18-2004, 08:07 AM
I believe the Finns ran at a higher initial speed, and used fully closed radiators initially.

There's also the question of whether they adjusted results to standard atmosphere conditions. If they didn't, and it was colder than standard atmos, (approx 15 c at sea level) then the performance would be inflated. If it was hotter, performance would suffer.

Somebody is currently translating the full report into English, so we should know the conditions soon.

If you compare the Finnish tests to the Rechlin test of a G1, the Finns achieved a higher climb rate at low alt, a worse climb rate at high alt. It could be that the fully closed radiators at the start had to be opened a lot later in the climb, reducing the climb rate.

But it's all speculation until we know the details of the testing procedure.

NN_Tym
09-18-2004, 11:19 AM
What really surprises me is the fact that the climbrate is constant in a test, and increasing in the other test...

Even with radiator settings being differeont, I guess the curves should share the same shape. Why don't they ?

steiner562
09-18-2004, 11:30 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by hop2002:
I believe the Finns ran at a higher initial speed, and used fully closed radiators initially.

There's also the question of whether they adjusted results to standard atmosphere conditions. If they didn't, and it was colder than standard atmos, (approx 15 c at sea level) then the performance would be inflated. If it was hotter, performance would suffer.

Somebody is currently translating the full report into English, so we should know the conditions soon.

If you compare the Finnish tests to the Rechlin test of a G1, the Finns achieved a higher climb rate at low alt, a worse climb rate at high alt. It could be that the fully closed radiators at the start had to be opened a lot later in the climb, reducing the climb rate.

But it's all speculation until we know the details of the testing procedure.<HR></BLOCKQUOTE>

yep idle speculation on your part which helps nothing.

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BBB_Hyperion
09-18-2004, 11:37 AM
Constant well look at the interpolation points .)

http://www.butcherbirds.de/hypesstorage/g/FinnishBf109G2MT215.jpg

here Rechlin Chart for g1

http://www.butcherbirds.de/hypesstorage/g/Me109G1climb.jpg
http://www.butcherbirds.de/hypesstorage/g/109G1_Rechlin.jpg

russian test.
http://www.butcherbirds.de/hypesstorage/g/russiang2.jpg

The reason why the climbrate stays relative constant is the increase of ps you can see here.
It increses to 2km then falls off .

http://www.butcherbirds.de/hypesstorage/g/DB605A.jpg

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Regards,
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NN_Tym
09-18-2004, 11:48 AM
Sorry, I made a typo, and told the vertical speed was constant on the Finn test... But it was on the Rechlin one.

On the Rechlin test, the vertical speed seem constant, between 0 and 2000m... Then it is rather linear, and curved on the other tests. Does it use another sort of graduation for the vertical speed ?

On the "Erla" test (not listed on your message), there is also a curve that constantly decreases. What does it show ?

Kurfurst__
09-18-2004, 01:31 PM
In the Finnish tests the Finns climbed at a greater than officially specified climb speed. They did not close the radiators themselves, left them on automatic but this higher climbspeed resulted more airflow through the radiator, and better cooling. Therefore the radiator thermostat opened the flaps less up to about 2000m than in the other tests, and still provided enough cooling. The reduced drag increased climb rate by a significant margin. Above 2000m, the flaps gradually opened out, to keep the temperature at 85 degrees (optimal for operation).



In the other tests, it`s possible that they were adjusted to the standard, constant radiator flap settings, and therefore after corrections the results are different. The fact that the 2000m+ climbs rates are very closely match each other point towards this. In any case, 4800 fpm climb rate was very impressive for 1942, and the highest for a fighter for years, especially as this was with a reduced rating (increased in 1943 by 10%, ROC should follow similiar change).

It should be noted that the tested Finn G-2 had higher drag than the normal G-2s, as it`s tailwheel was non-retractable on this particular aircraft.

Can`t find the Erla testing of that G-1, but from memory, they show the corrected results of flight tests at Erla, higher compared to the calculations at Messerscmitt. It also seem to show raw climb data, something around 22 m/sec rate of climb at SL. Without the exact conditions and correction applied to the plane however, these numbers tell little.

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BBB_Hyperion
09-18-2004, 02:03 PM
Is that the erla test you mean ?

http://www.butcherbirds.de/hypesstorage/g/bf109g1-erla.jpg

For the climbrate on rechlin test i think you are correct its a little flated out and 21 m/s at 0 1 and 2 k is something to note . Cause it doesnt fit to the other charts in form and detail.

High Ground is not only more agreeable and salubrious, but more convenient from a military point of view; low ground is not only damp and unhealthy, but also disadvantageous for fighting.

Sun Tzu : The Art of War

Regards,
Hyperion

NN_Tym
09-19-2004, 12:31 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Kurfurst__:
In the Finnish tests the Finns climbed at a greater than officially specified climb speed. They did not close the radiators themselves, left them on automatic but this higher climbspeed resulted more airflow through the radiator, and better cooling. Therefore the radiator thermostat opened the flaps less up to about 2000m than in the other tests, and still provided enough cooling. The reduced drag increased climb rate by a significant margin. Above 2000m, the flaps gradually opened out, to keep the temperature at 85 degrees (optimal for operation).<HR></BLOCKQUOTE>Do you mean that the best climb speed given in Bf109G2 manual is not the best one ? Does it mean the Finns discovered the best climb speed in this test ?
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>In the other tests, it`s possible that they were adjusted to the standard, constant radiator flap settings, and therefore after corrections the results are different. The fact that the 2000m+ climbs rates are very closely match each other point towards this.<HR></BLOCKQUOTE>I don't understand. What was the common practice for climbrate test with Bf109 ? I thought it was to be as close as possible to combat settings. So I thought they only used automated cooling flaps, and automated pitch. Am I wrong ?

faustnik
09-19-2004, 12:36 PM
One thing has become very clear with all of the climb tests presented in this forum. Not all countries used identical methods in their testing. Comparing data from different countries would be very difficult.

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NN_Tym
09-20-2004, 01:39 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by BBB_Hyperion:
Is that the erla test you mean ?

http://www.butcherbirds.de/hypesstorage/g/bf109g1-erla.jpg<HR></BLOCKQUOTE>Yes, that's the one I was thinking of.

If I understood the text right (but my translation is based on isolated words as I can't speak German), then Kurfurst is right. There are two curves that look a lot like the Finnish and Russian ones : first the climbrate increases, then it is decreasing in a curved way, and finally, you get a linear drop. Those lines describe calcultated values by Messerscmitt. Are each for a different boost value ?

The last one, decreasing all the way, is measured (rather than calculated) by Erla ?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>For the climbrate on Rechlin test I think you are correct its a little flated out and 21 m/s at 0 1 and 2 k is something to note . Cause it doesnt fit to the other charts in form and detail.<HR></BLOCKQUOTE>The table confirms that constant 21m/s value between 0m and 2000m.

I have one question about the Russian curves. What each curve do represent ? Different boost values (1.3 ATA and 1.42 ATA ?).

What I don't understand, is that the Finnish test should give the worst result : front line machine with no preparation for the test, non retractable tail wheel, unorthodox use of the radiator flaps (if Kurfurst is right)... Yet these are the best, by far, results at low altitude.

From this simple example), Faustnik is right, it is very difficult to compare test from different countries. But this is the meat and bread of this board it seems, it would be nice to use this example to make some points clearer for everyone...

Kwiatos
09-20-2004, 02:39 AM
I flew yesterday in Bf 109 G-2 at dogfight mission (full real) and i meet Hurricane Field Mod. at 4 km. Hurricane start to spiral climb with me. I though "i got him" because i know that Bf G-2 was very good in spiral climb and should be much better than Hurricane. After some circles in spiral climb when we get 5 km i was in shock. Hurricane got adventage in high and position and soon get my six. These game still wonder my day by day.

Kurfurst__
09-20-2004, 03:27 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by NN_Tym:
If I understood the text right (but my translation is based on isolated words as I can't speak German), then Kurfurst is right. There are two curves that look a lot like the Finnish and Russian ones : first the climbrate increases, then it is decreasing in a curved way, and finally, you get a linear drop. Those lines describe calcultated values by Messerscmitt. Are each for a different boost value ?
<HR></BLOCKQUOTE>

No, all for the same boost, 1.3ata.


Erla`s (~19.3), appear to be the flight test results conrrected to a given standard.

Mtt`s (~18.7) appear to be calculations, and are somewhat lower than Erla`s measured figures.

The third line, 22.8, is most likely the actual rate of climb recorded, which was later corrected to standard setting, most likely the radiator`s. It is very likely that when they started to climb, the engine was cold, and the radiators were in minimal drag position.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
I have one question about the Russian curves. What each curve do represent ? Different boost values (1.3 ATA and 1.42 ATA ?).<HR></BLOCKQUOTE>

With and without gunpods ("three point/gun and five point/gun" the label says), at 1.3ata I believe.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
What I don't understand, is that the Finnish test should give the worst result : front line machine with no preparation for the test, non retractable tail wheel, unorthodox use of the radiator flaps (if Kurfurst is right)... Yet these are the best, by far, results at low altitude.<HR></BLOCKQUOTE>

I think those numbers are fairly ok. Remember, the finns let the radiator to be adjusted by a thermostat, so it was closed in the intitial climb, and it`s a considerable drag factor, well over 50 km/h can be lost when it`s fully open, and the theremostat tries to maintain it at a rather low temperature, 85 degrees - the DB 605 A was allowed to run at 115 degrees for a 10 minute period if needed, so in real life, pilots who knew this could safely close the radiators much more than the thermostat would.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
From this simple example), Faustnik is right, it is very difficult to compare test from different countries. But this is the meat and bread of this board it seems, it would be nice to use this example to make some points clearer for everyone...<HR></BLOCKQUOTE>

Indeed, a LOT depends on the standards to which the obtained results were corrected after measurments. In example, the German standard correction for 109s was the use of apprx. half open radiators (ca. 220mm open exit) up to rated alttude (5.8 km for the G-2), then gradually closing them so by the time the ceiling (~12km) was reached, they would be closed 1/8-1/10 (ca40-50mm). Even this was a worser condition than in RL, where it`s stated the thermostat would already close the flaps at about 7-8 km altitude. And as said, even a half open state was not required at the lower altitudes, higher temperatures than 85 degrees celsius could be used very safely. However, that 85 degrees is generally the optimum to run all combustion engines, even car engines are regulated to that temperature.

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We're walking in the air
We're floating in the midnight sky
And everyone who sees us greets us as we fly