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View Full Version : Bf109 E/B Why so fast down low?



LG1.Farber
Jun-23-2013, 16:41
Apart from a 9 litre tank of extra oil for the lubrication problems I see no reason why the Jabo version are faster at medium to lower alts but have worse than pre TF mod performance above 5k. Can some one from TF show evidence for this?

Ive researched my own materials but cant find any evidence to back TF's decision.

Thanks in advance.

RAF74_Buzzsaw
Jun-23-2013, 17:05
Apart from a 9 litre tank of extra oil for the lubrication problems I see no reason why the Jabo version are faster at medium to lower alts but have worse than pre TF mod performance above 5k. Can some one from TF show evidence for this?

Ive researched my own materials but cant find any evidence to back TF's decision.

Thanks in advance.

The Jabos are equipped with low altitude optimized version of DB601. "Aa" model instead of A-1. See the Wiki page.

This engine has a Full Throttle Height of 3700 meters instead of 4500 for the standard version. It generates more power down low, but runs out of power at higher altitudes sooner. It's a function of the supercharger gearing.

It is undoubtably true that some of the Jabo versions of the 109 were equipped with the standard engine, but we elected to simplify things and give all the E-3 and E-4 Jabos, (the upcoming E-1B which will have the standard DB-601A) the DB-601Aa engine.

Gromit
Jun-24-2013, 11:01
Does anyone have the performance/power figures of the relative sub marks?

I get a bit baffled by these sub marks myself, the 109e4N was supposed to have an engine optimised for high alt yet seems to have greater speed and climb down low than the 109E4, that's a subjective statement of course as I have not seen the figures for either?

92 Sqn. Philstyle (QJ-P)
Jun-24-2013, 11:25
Does anyone have the performance/power figures of the relative sub marks?
?

Bah! I had asked this same question a few months back. I was kindly provided with a link to where this information was in the TF wiki.
However, I can't find it again now!

The pages for each aircraft under the flight manuals section do not have this, that I can find.....
http://www.theairtacticalassaultgroup.com/wiki/doku.php?id=germanflightmanuals


Aha! I found the thread:
11 May 2013: http://theairtacticalassaultgroup.com/forum/showthread.php?t=3877&page=2&highlight=performance

Kodoss had posted a datasheet for the E1/E3, but I cannot find for the other aircraft types.
http://www.theairtacticalassaultgroup.com/wiki/doku.php?id=hbf109edatasheet


As far as I can tell, we are still missing a like-for-like set of performance data as we have for the RAF aircraft, in the wiki.

RAF74_Buzzsaw
Jun-24-2013, 12:03
Does anyone have the performance/power figures of the relative sub marks?

I get a bit baffled by these sub marks myself, the 109e4N was supposed to have an engine optimised for high alt yet seems to have greater speed and climb down low than the 109E4, that's a subjective statement of course as I have not seen the figures for either?

The DB-601N is optimized for high altitude performance, but also has more power overall than the standard DB-601A, even at low altitudes.

As far as performance for the various aircraft is concerned, it is taken from a number of sources, I am not going to quote or post all of them here, anyone who is knowledgeable and who is willing to travel to and spend a lot of time at museums and other locations can gather them. Suffice it to say we have spent many many years accumulating the documents and data.

Some aircraft had their performance estimated, for example, we know the performance of the earlier marks of the 109E, but the E-4N has no known tests available. In this case, using the earlier marks as a template, and factoring in the correct PS output for the DB601N engine, as well as the weight of the 109E with the DB-601N, provides the performance you see with this aircraft in the game.

We do not claim to provide the 'perfect' performance of the historical aircraft, that is frankly impossible, since every engine varied, typically there was a 5% difference in output between different engines as they came off the production line. Our knowledge of the game also limits our ability to replicate performance, as we gain mastery over the code, we expect to continue to refine and improve aircraft behaviour and performance.

Anyone who is unhappy with our work, we would encourage them to create their own mod.

Kwiatek
Jun-24-2013, 12:15
Things are little complicated here both IRL like in TF mod now.

Truly speaking 109 E/B (Jabo) version mostly used DB601Aa which was designated more for lower altititude flying then standart Db601A ( 601A had more power at lower alts but also less power at higher alts).

IRL we got such engines for 109 E version:

1. DB601 A - most used in typical figher version

- with older supercharger - FTH at 4.0 km - used mostly in early 109 E series but probably not in BOB era period
- with newer supercharger - FTH at 4.5 km - most common engine used in 109 E-1,E-3,E-4 series - 1.4 ATa 2400 RPM take off power 1 minut power, 1.3 Ata 2400 RPM emergency ( 5-minutes) power

2. Db601 Aa - with low level supercharger - FTH 3.7 km - used probably mostly for jabo Emils and probably in minor other fighter version - 1.45 Ata 2500 RPM take off 1-minute power, 1,35 Ata 2400 RPM emergency power ( 5 mnutes)

3. Db601N - C3 fuel - FTH at 4.9 km - used in E-4/N and later types - 1.35 Ata 2600 RPM emergency ( take off power - 1 or 3 minutes_, 1.25 Ata 2400RPM ( climb and combat 30 minutes power)


DB601 A-1
Up to 1,100 PS (809 kW) at sea-level with 2,400 rpm, up to 1,020 PS (750 kW) at 2,400 rpm and 4.5 km altitude, B4 fuel
DB601 Aa
Up to 1,175 PS (864 kW) at sea-level with 2,500 rpm, up to 1,100 PS (809 kW) at 2,400 rpm and 3.7 km altitude, B4 fuel

" The Aa ('a' is for 'ausland', ie. export engines) was sporting a reduced capability supercharger (vs. A-1), so the altitude performance was not that good as in A-1. However, since the supercharger was also drawing less power to drive, more power under full throttle height was available for the propeller, eg. 1100 PS at 1,6km vs. 1050 (5 min rating), or 1175 at sea level vs. 1100 (1 min rating), Aa vs. A-1. "


Actually we got in TF mod 109 fighter verision:
109 E-1 - with Db601A at 1.4 Ata ( older supercharger) - correct
109 E-3 - hybrid engine with power rating from DB601Aa ( 1.45 Ata) and higher alt supercharger from Db601A - not correct
109 E-3/B with DB601Aa at 1.45 ATa with lower alt supercharger - correct
109 E-4 - hybrid engine with power rating from DB601Aa ( 1.45 Ata) and higher alt supercharger from Db601A - not correct
109 E-4/B - with Db601Aa at 1.45 Ata - with lower alt supercharger - correct
109 E-4/N with Db601N at 1.35 emergency - correct

So 109 E/B with Db601Aa ( jabo version) had more power at lower alts then typical fighter version with Db601A but still if they carry bomb racks it shouldn't be faster then any fighter version with DB601A becasue of higher drag. Jabo version need more take off power to overtake more weight and drag of bomb and rack. Theoretically Jabo version could be little faster at lower alts then standart 601A version only if not carry any aditional drag (bomb racks) but it want be jabo then. Also improtant to know is that new windshield of 109 E-4 was more draggy then earlier version ( used in 109 E-3) the same like armoured windshield and it cost also about 10-20 kph.

For me it looks that Jabo version of 109 E dont have aditional drag casued by bombs and bomb racks and they are too fast comparing to other versions.

Im sure that TF made great job with flight models and performacne of these planes ( as engine and code allows to do) but nothing is perfect so still there are some errors expecially in engine power ratings with 109 E-3 and E-4 version.

And here some nice read about Oberleutnant Hans-Ekkehard Bob E-4/B version:

http://www.pewteraircraft.com/LUFTWAFFE/Bf109E4B%20148%20HE%20BOB/Bf109E4B%20148%20HE%20BOB.htm

RAF74_Buzzsaw
Jun-24-2013, 12:44
1. DB601 A - most used in typical figher version

- with older supercharger - FTH at 4.0 km - used mostly in early 109 E series but probably not in BOB era period

Our research indicates E-1's still typically retained the older engine, so we have modelled it.




109 E-3 - hybrid engine with power rating from DB601Aa ( 1.45 Ata) and higher alt supercharger from Db601A - not correct
109 E-4 - hybrid engine with power rating from DB601Aa ( 1.45 Ata) and higher alt supercharger from Db601A - not correct

Information from German sources and captured aircraft indicate 1.45 ata was being used by the DB-601A with 'Neuem' supercharger. So we modelled it.



So 109 E/B with Db601Aa ( jabo version) had more power at lower alts then typical fighter version with Db601A but still if they carry bomb racks it shouldn't be faster then any fighter version with DB601A becasue of higher drag. Jabo version need more take off power to overtake more weight and drag of bomb and rack. Theoretically Jabo version could be little faster at lower alts then standart 601A version only if not carry any aditional drag (bomb racks) but it want be jabo then. Also improtant to know is that new windshield of 109 E-4 was more draggy then earlier version ( used in 109 E-3) the same like armoured windshield and it cost also about 10-20 kph.

For me it looks that Jabo version of 109 E dont have aditional drag casued by bombs and bomb racks and they are too fast comparing to other versions.

Drag as a result of bombracks and bombs is modelled in the original game. We have changed nothing there. If you remove the rack from a Jabo model, you will see a gain in level speed compared to leaving it on. If an argument can be made to the effect that the original game's drag modelling is incorrect, we may consider changing it. In the meantime, we have more important issues to work on.

Regarding the E-4 windshield, please post documents showing the increased drag of this windshield and the loss of speed resulting. We have seen nothing relating to this which details specific performance effects. Without detailed information we cannot consider implementing this.

A note also, we will not respond to every and all comments and complaints about performance on this board. The time spent responding means less time available to work on improving the game.

Robo.
Jun-25-2013, 01:04
Does anyone have the performance/power figures of the relative sub marks?

I get a bit baffled by these sub marks myself, the 109e4N was supposed to have an engine optimised for high alt yet seems to have greater speed and climb down low than the 109E4, that's a subjective statement of course as I have not seen the figures for either?

What Buzzsaw said - the TF patch reflects historical development of the DB601 series engine. The difference between E-4 and E-4/B has been explained already, by different subversion with different PS and FTH, all depending on supercharger. Basically, JaBos needed more PS down low so generally, these engines were primarily fitted into JaBos. Of course there were standard E-4s with Aa engine and vice versa, JaBos with normal A-1. It is not possible to model all combinations of engines, armament etc without having too many variants in the sim. Consider TF patch as a huge step forwards in terms of engine development modelling (compared to vanilla Emil), yet still simplified to keep it organized and with focus on the main variants and principles (e.g. only 2 or 3 out of 10 DB 601 engines built were Aas). The sub-variants still confuse people not familiar with engines and their history. Same with Rolls Royce where TF added Merlin II and iproved modelling of the III and XII.


In the case of 601N it's also the case of improved design and using different fuel. The PS was indeed much higher up high as well as down low, basically identical to the of Aa at SL. As for hard evidence and figures, Kurfurst's website contains all data sheets for these variants:

http://kurfurst.org/Engine/DB60x/DB601_datasheets_N.html

Navigate with the arrows on the bottom to A-1 or Aa to see the differences in data and power curves. You will find that TF did lots of research and the reality in the sim now correspondents with the historical development and all main types and sub-types are represented reasonably. It will never be absolutely perfect, but it is with no doubt better than the stock version with one engine for all 109s that was wild combination of all above engine sub-variants regarding PS and FTH... :thumbsup:

Gromit
Jun-25-2013, 08:25
Thanks guys, not complaining, just find little info available on the sub types!
Anyone recommend a good book about the 109 development? only one I have is Decisive Duel.
regards
Mike.

RAF74_Buzzsaw
Jun-25-2013, 13:01
Kurfurst's website contains all data sheets for these variants:

http://kurfurst.org/Engine/DB60x/DB601_datasheets_N.html

Actually Kurfurst's site lacks a number of the documents which we collected and used in assessing performance for the DB-601N.

RAF74_Buzzsaw
Jun-25-2013, 13:52
Thanks guys, not complaining, just find little info available on the sub types!
Anyone recommend a good book about the 109 development? only one I have is Decisive Duel.
regards
Mike.

There are no 'Perfect' books out there on the 109, but one which I would certainly recommend is "Messerschmitt Bf109 1935 Onwards, (all Marks) Owners Workshop Manual" by Haynes publications and co-authored by the mechanic who worked on Black Six. There is a lot of technical detail which is missing in other books which deal more with the operational history.

http://imageshack.us/a/img526/2609/covervcw.jpg

The other thing is to study the contents of the WWII Aircraft Performance site, there is a lot of information there:

http://www.wwiiaircraftperformance.org/

Kwiatek
Jun-25-2013, 16:58
More detailed link:

http://www.wwiiaircraftperformance.org/me109/me109e.html

Backing to 109 E/B performance here is data for 109 E/B version with 500 kg bombs load and without it at different power settings from 1.3 Ata ( 5-minutes power setting) till 0.85 Ata from 1 km till 7 km

3159

3160

Here is data for Db601A with old and new supercharger:

http://kurfurst.org/Engine/DB60x/DB601_datasheets_A1.html

Here for DB601Aa

http://kurfurst.org/Engine/DB60x/DB601_datasheets_Aa.html

and power curve for 601Aa

3162

- more power and ATA at low alts due to cropped supercharger ( 1175 HP at 1.45 Ata 2500 RPM sea level) but less at higher alts then in DB601A ( 1100 HP at 1.4 Ata 2400 RPM sea level)


BTW these book look interesteting alhough i dont have it maby some owner could say something more:

http://www.amazon.co.uk/dp/190322327X

LG1.Farber
Jun-25-2013, 21:20
Thanks guys, not complaining, just find little info available on the sub types!
Anyone recommend a good book about the 109 development? only one I have is Decisive Duel.
regards
Mike.

Me109 Recognition manual. Knocks the socks off of the Haines manual which I found disappointing because it was as much like a heines manual as i thought.

VO101_Kurfurst
Jun-26-2013, 06:06
Actually Kurfurst's site lacks a number of the documents which we collected and used in assessing performance for the DB-601N.

... and which documents would that be...?

DB 601N performance is plainly in the engine's own manuals and power curves.

http://www.palba.cz/forumfoto/albums/userpics/12062/db601n.jpg