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Author Topic: Bf109G climb with MW50  (Read 973 times)

Offline George

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Bf109G climb with MW50
« on: December 26, 2005, 11:15:31 AM »
GL/C-E2 shows following climb time up to 6 km altitude:
G-14 - 6.0 min
G-14/ASM - 6.5 min
G-14/U-4 - 7 min
G-10/U-4 -7.5 min
G-10/R-6 - 7.5 min
K-4/DB605D - 7.5 min

It seems that it's without MW50

Does anybody have info about climb time (or climb speed, m/sec)
of later Bf109 WITH MW50?
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Offline Krusty

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Bf109G climb with MW50
« Reply #1 on: December 26, 2005, 11:19:25 AM »
I don't have real numbers, but in AH2 it takes a few seconds short of 10 minutes to get to 30k in a 109K-4, so that would be (30k / 10min) = 6.666... minutes to get to 20k (close to your posted 6km alt)
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Offline gatt

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Bf109G climb with MW50
« Reply #2 on: December 27, 2005, 02:21:03 AM »
IIRC, both the G-10 and K-4 (even with 1.8ata) should take less than 6min to get to 6Km. The G-14 should climb very well up to about 15K and then less and less.
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Offline LLv34_Snefens

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Bf109G climb with MW50
« Reply #3 on: December 27, 2005, 03:43:23 AM »
Quote
Originally posted by Krusty
I don't have real numbers, but in AH2 it takes a few seconds short of 10 minutes to get to 30k in a 109K-4, so that would be (30k / 10min) = 6.666... minutes to get to 20k (close to your posted 6km alt)


That would only be the case if climb was constant.
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Offline Krusty

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Bf109G climb with MW50
« Reply #4 on: December 27, 2005, 10:22:22 AM »
well, when I ran the test, it only dropped off at about 18k. It was pegged to the "4" mark on the climb meter until then, so that's fairly close.
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Offline Kurfürst

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Bf109G climb with MW50
« Reply #5 on: December 27, 2005, 02:52:46 PM »
The number you posted from the GLC charts refer to a ROUGH time to 6km using 30-min power Kampfleistung in each case. These are not precise numbers.

Using maximal power (w. MW), the performance curves I have for Bf 109K show :

40 secs to 1km
1m 22 to 2km
2m 05 to 3km
2m 50 to 4km
3m 38 to 5km
4m 29 to 6km
5m 30 to 7km
6m 42 to 8km
etc.
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Offline George

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Bf109G climb with MW50
« Reply #6 on: December 28, 2005, 12:53:47 AM »
Dear Kurfurst

Your climb data is impressive.
What engine and boost pressure have been used to obtain such climb?
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Offline gatt

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Bf109G climb with MW50
« Reply #7 on: December 28, 2005, 01:26:55 AM »
Could be a DB605DC with 1.98ata, 2.000hp, MW50 and C3 fuel?
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Offline Kurfürst

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Bf109G climb with MW50
« Reply #8 on: December 28, 2005, 03:41:07 AM »
Yep, 1.98 ata. I'll look up for 1.8ata too.

The values refer to half-open radiators up to the rated alt (VDH) of 4900m, and then they progressively close to about 1/8th of that opening by the time they reach the ceiling. This is a somewhat conservative standard for 109 climbs, they note the shutters already reach that 1/8th 'Schnellflugstellung' about 1000m above the rated alt. The radiators were automatically controlled according to coolant temperature - constant half-open position, esp. at the start of the climb when the engine was still cool. The shutter position had considerable effect on drag and thus climb rate.

The get some idea about the effect of the radiator flap position, the Finnish climb test of the 109G-2 at a mere 1.3ata (1310 PS) boost resulted in a peak 24.3 m/sec climb rate, merely because they started the climb at higher speed then recommended, resulting more airflow  in the radiators for better cooling, and the automatic kept them shut ealrly in the climb.
From other docs it appears that the near-fully open radiators resulted in some 60 kph speed loss due to drag at SL.

In view of that, I believe the 109K climb times are rather conservative. The 109G-2 at 1.3ata could already climb to 5000m in just 4min 11 sec after all.

I also have some papers for the G-14 and G14/AS w. MW, however the curves are for the 20mm gondies version (ca-2m/sec from RoC), from which and the 109K curves I believe ca23m/sec is a very reasonable initial rate of climb for the 109G-14.
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Offline gatt

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Bf109G climb with MW50
« Reply #9 on: December 28, 2005, 03:45:37 AM »
Hello Kurfurst,
is it possible to give a look at the G-14 perf charts?
Thanks for any help.
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Offline George

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Bf109G climb with MW50
« Reply #10 on: December 28, 2005, 08:24:22 AM »
Dear Kurfurst

I have Steiggeschwindigkeiten of Bf109K4 DC/ASC fur Grundeinstellung 1.98 ata u. 1.8 ata mit Schrb. 12199 u. 12159

Max Wst (vertical speed) is abot 21.6 m/sec
(for 109K4 Start-Notlstg, PL 1.8, Grundeinstllg 1.8)
Strange thing, Wst of 109K4 Start-Notlstg, PL 1.8, Grundeinstllg 1.98 is less and equal 20 m/sec
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Offline Kurfürst

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Bf109G climb with MW50
« Reply #11 on: December 28, 2005, 10:37:16 AM »
Hi all,

re : the G-14 charts, I'd have to find them first, I don't have them scanned yet. But based on the 109K charts, and the effect of weight difference (apprx. -100kg = + 1 m/sec), it's fairly accurate.

George,

I think the chart you refer to is the one that floats around the net, I think it's the the one that shows the DC engine 'o. MW' (=ohne MW, without MW50 injection), just relying on C-3 fuel alone. Without MW50 injection, the DC would develop at SL :

When set to 1.98ata, running at 1.8ata : 1725 PS
When set to 1.8ata, running at 1.8ata :   1800 PS

This explains why the '1.98ata' climb rates are lower - it merely refers to an engine setup when 1.98ata maximum boost was set (which would require C3 + MW), but only C3 was used.. I guess it's not the proper setup, ie. spark plug timing must have been different as well for 1.98ata. I can't confirm that yet, but seems very likely.

 Note that the DC could run at various settings, the above two w/o MW50 injection (esp. 1.98/1.8) are atypical and rather theoretical - the only case I can think of this happening when the rear MW tank was used for extra fuel storage instead for 118 liter extra tankage.

The chart I (also) have shows the Sondernotleistung with MW injection at 1.98ata. SL RoC is 24.5m/sec, increasing to 25 at around 600m altitude.

Please contact me both of you at kurfurst@atw.hu. I cannot promise I will reply immidiately, but I will when I have time. Especially George, I have some Russian 109 stuff which I can't translate exactly. ;)
« Last Edit: December 28, 2005, 10:39:32 AM by Kurfürst »
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Offline Angus

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Bf109G climb with MW50
« Reply #12 on: January 02, 2006, 01:00:07 PM »
1.98 ATA as well as 1.8 ATA were not that common.
A 109G6 would yet climb to 20K in less than 7 minutes.
(6.5 from memory)
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Offline Kurfürst

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Bf109G climb with MW50
« Reply #13 on: January 03, 2006, 06:20:20 AM »
1.8ata was common (it was the minimum setting for the 605DB engine). The early 605DM would run at 1.75ata, but that's only 1800 vs 1850 PS difference, moreover it seems the DB 1.8ata was also 1800PS after spark plug timing was altered.

As for 1.98ata, I think it's a horse beaten to death. It was definietely used in numbers late in the war, butch2k says so and I belive him. Moreover we have that March 1945 order saying that four wings from JG 27 and JG 53 will use 1.98ata boost etc.

As for the G-6 time to alt data you posted, it comes from the GLC datasheets, which are 'rough' numbers, and refer to the 30-min climbing power, but 6-7 mins looks correct, depending on the version of plane. For example the 109K was listed at 7.5 mins to 20k - it's 30-min power only again. It's just about the same in every air force, they give some time for military power only, nobody was climbing at WEP to wear out the engine when there was no need.
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Offline Angus

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Bf109G climb with MW50
« Reply #14 on: January 03, 2006, 08:51:57 AM »
Minimum setting?????????????????
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It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land. (Werner Mölders)
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