Correcting the DB 603A (Me 410) 1.4 ATA Start & Notleistung (WEP) timer from 1 min -> 5 min

January 15

Note: First of all, thanks to the team for the recent updates to the DB605A series engines. Its great to have available in-game the modifications and changes that were made to the Bf 109 G and Bf 110 G from 1943, the increased emergency timer limit (3 minutes) has had a substantially positive effect on players desire to fly these particular variants, just as it has with the P-40, P-39 etc. Rather than deliberately steering clear of them when other alternatives are there.

I'd like to raise the DB 603A (+Aa) engines of the Me 410 as a priority for correction regarding WEP time. It's a heavy twin engined fighter that really relies on a strong engine output to minimise the closure speed of attacking fighters and defend itself. This applies in 1943, but desperately so in a 1944 environment. Some of the combat reports in 1944 are about as as intense as you'll ever read, there were experienced pilots diving away and being chased from 25,000 feet down to the deck by the USAAF.

What is important to note, is that the DB 603 was not considered an engine plagued or even mentioned as having particular reliability issues when it was introduced, unlike the DB 605. It was slow to enter production, but in fact one of the reasons this engine was chosen for the redesigned Me 410 was to provide more reliable and improved power output compared to the DB 605. This was following bad experience with the very troubled and controversial Me 210C programme (initially using the DB 605) which was considered underpowered for such a heavy machine. This led to the Bf 110 continuing service beyond its expected withdrawal, as the Me 210 was not a satisfactory replacement and was barely offering similar performance to the Bf 110 G at the time, while suffering a plethora of aerodynamic and stability issues. The Me 410 did address to a large extent the fundamental handling and performance issues, and the DB 603 was an important part of that.

Typical operating limits at emergency power for aero engine manufacturers of the time was 5 to 10 minutes, in the majority of applications for fighter aircraft it was 5 minutes. That's a fairly universal and practical time that was given by many manufacturers to give some kind of predictable estimate of operational hours before servicing, maintenance and overhaul was expected. There were of course variations for specific purposes, reasons and applications. Wartime materials shortages, design and reliability issues and cooling limitations did cause some manufacturers to reduce boost/time on emergency power. The story with Daimler Benz's DB 605 is a well known example that's been discussed on this forum, with various mitigating actions carried out during the war to try improve the situation.

I've spent some time reading through the engine handbook for the DB 603A (Motorhandbuch DB 603A Nov 1942 - AE 603 / V.8.42), and there's no explicit reference to an emergency power time limitation that I can find. I know others in the community have been looking as well, so this shouldn't come as a surprise.

The absence of an explicitly defined limit with the DB 603 either in the manual or elsewhere; and no evidence of a limiting technical order to the Me 410 or anything suggestive of this in communications by the manufacturer, pilots, German industry or political circles etc strongly suggests its engine was reliable enough to maintain a standard output of 5 minutes. I think its reasonable to conclude that Daimler Benz applied lessons learned to the DB 603 following the earlier DB 605's troubled introduction and reliability issues (cooling system, oil distribution, materials, extensive testing under high stress, quality controls). The only mention I've seen is for pilots to monitor their oil temperatures when flying for extended periods, as the Me 410 had a fairly long endurance... but that does not seem anything out of the ordinary.

Attached is an extract of a table listing power output etc from the engine handbook, I've highlighted in blue one particular note - which states for outlet temperatures: "Highest permissible outlet temperatures. Short Term (10 min max)".

I'm not sure exactly how to interpret this specific note with regards to emergency power limitation, but it certainly indicates to me that the engine can tolerate thermal stress quite well. I'd be interested to hear others thoughts on this.

Having also re-read through Calum Douglas's masterpiece of a book "The Secret Horsepower Race" which focuses on research and development of German aero engine development, and does of course mention the DB 603... its noteworthy that there is no mention of specific or significant reliability issues with the DB 603. In fact, it should be highlighted that the DB603 was a development of the earlier DB 601, not the "sick" DB 605 and so did not inherent any of its specific flaws.

In either case, can we have the emergency power time/limit corrected to 5 minutes for the Me 410, as there is no evidence that the DB 603 engine was being de-rated or limited... in clear contrast to the DB 605.

Cheers

January 17

all manuals I have dont mention a limit, but it should probably more the 3 and 30min limit for Start&Notleistung und Steig&Kampfleistung.

January 17

1 hour ago, the_emperor said:

all manuals I have dont mention a limit, but it should probably more the 3 and 30min limit for Start&Notleistung und Steig&Kampfleistung.

Good to know on the manuals, cheers @the_emperor

Thing is, I don't see any evidence to suggest 3 minutes was required as a limitation on the DB603, 5 minutes was the default standard for these aero engines. It was only when mechanical reliability was in question did these lower limits seem to come into place, but I'm all ears if you understand differently.

The later DB 603 G (and A with MW50) versions of these engines (not ingame) appear to be capable of up to 10 minutes emergency power, (subject to the outlet, coolant temperatures being managed).

Edited January 17 by Aurora_Stealth

January 17

1 hour ago, Aurora_Stealth said:

Thing is, I don't see any evidence to suggest 3 minutes was required as a limitation on the DB603, 5 minutes was the default standard for these aero engines. It was only when mechanical reliability was in question did these lower limits seem to come into place, but I'm all ears if you understand differently.

The later DB 603 G (and A with MW50) versions of these engines (not ingame) appear to be capable of up to 10 minutes emergency power, (subject to the outlet, coolant temperatures being managed).

Yes, for the British/US/Ussr 5min was the usual WEP time.

the Germans used 3min WEP in generell.

as for MW-50 (Wet WEP) the longer times can be attributed to heat, they run cooler than non-wet WEP settings (hence why the time limit is short to avoid the risk of detonation).

Same with US wet-WEP (P51H, P47N) settings, they are allowed for longer periods than dry WEP.

Edited January 17 by the_emperor

January 17

5 hours ago, the_emperor said:

Yes, for the British/US/Ussr 5min was the usual WEP time.

the Germans used 3min WEP in generell.

as for MW-50 (Wet WEP) the longer times can be attributed to heat, they run cooler than non-wet WEP settings (hence why the time limit is short to avoid the risk of detonation).

Same with US wet-WEP (P51H, P47N) settings, they are allowed for longer periods than dry WEP.

Hmm, that's interesting with regards to the Germans - I didn't realise that they used that lower (3 min) limit more generally but it makes sense in the context regarding their engine limitations and issues more broadly.

Yep, I understand the backstory regards MW50 and the other water injection cooling methods. It definitely helped the Germans out with their typically more sensitive engines and issues with overheating and knock etc which is a subject in itself and quite well covered in Calum's book.

That being said... I'm still fairly confident on the point with regards to the DB603, it seems a better designed, less rushed and more robust / reliable engine compared to many of the other German engines. As mentioned, there seems to have been a real effort to learn lessons prior to getting it into production. Accepting the need for a larger engine size to ensure all that... seems to fit in with the application in the Me410.

As a side note - It sounds like many timers should be revised then from 1min to 3min across the board for many other German aircraft in that case.

Edited January 17 by Aurora_Stealth

January 17

55 minutes ago, Aurora_Stealth said:

As a side note - It sounds like many timers should be revised then from 1min to 3min across the board for many other German aircraft in that case.

As it was done in the recent updates...took about 5-6 Years but eventually it was corrected.

One thing to keep in mind is, that twin engines Zerstoerer have only one radiator per engine. so high temps are even more of a concern at WEP setting.

January 18

23 hours ago, the_emperor said:

As it was done in the recent updates...took about 5-6 Years but eventually it was corrected.

One thing to keep in mind is, that twin engines Zerstoerer have only one radiator per engine. so high temps are even more of a concern at WEP setting.

Very valid point, and yes agreed cooling the engines on these twin engined aircraft is generally harder to achieve/manage due to location of the engines, aerodynamics and complexities in general to a single engined fighter.

That being said, what we do know is the DB605 in the Bf 110 G was eventually able to use 3mins emergency power by 1943 with changes and modifications.

The DB603 engine, by design; was much more efficient in terms of heat generated relative to its output. And while only using one radiator per engine compared to single engined fighters, these radiators on the Me410 were much larger and more efficient than on the Bf 110 G. The radiator design/technology itself was improved on the Me410 again as a direct lesson learned from other aircraft including Bf 109, Bf 110.

The radiators on the Me410 were also better integrated, with airflow routing around the more streamlined engine nacelles and airframe. This improvement gave less drag, less turbulent airflow around the wing/oil radiators.

Edited January 18 by Aurora_Stealth

January 24

On 1/18/2025 at 2:20 PM, Aurora_Stealth said:

The DB603 engine, by design; was much more efficient in terms of heat generated relative to its output.

In deed. when you compare the Performance output to displacement its a fairly low performing engine, which might in itself run cooler and less stressed...sofar I have not seen any time limits even for the climb&combat setting.

January 24

9 hours ago, the_emperor said:

In deed. when you compare the Performance output to displacement its a fairly low performing engine, which might in itself run cooler and less stressed...sofar I have not seen any time limits even for the climb&combat setting.

Yep, by that measure it can be described as relatively uncompetitive but we know the reasons why i.e. materials and alloys supply being far more limited, supply of high grade fuel being more limited, radiator developments previously being unsatisfactory; among all the other things described going on with production and logistics as described earlier. This all seemed to lead towards using a more conservative design philosophy on the DB 603 to achieve a more reliable and sustainable high power, high torque output... even if not as efficient with regards to displacement.

To increase that output ratio, the engine would have had to use even higher boost pressures and therefore be higher stressed; something that was harder for the Germans to accommodate with the above limitations... otherwise they'd need a mandatory water/methanol cooling system to achieve improved cooling like with the DB 605 A or to once again deal with degraded reliability. Some MW50 kits were used on a small, select number of late Me410's I believe, but frankly the aircraft was overweight as it was, so carrying more weight wasn't a great solution either.

Edited January 24 by Aurora_Stealth

January 27

Please find below substantiating information and evidence which is well described within Calum's book (The Secret Horsepower Race). This information gives quite a good overview of how the DB 603 was better able to sustain increased power without the limitations of earlier designs such as DB 605 which had to be conservatively limited in emergency power, quotes are also included further down...

The DB 603 oil cooling was more efficient:

Thorough coolant flow analysis carried out on DB603 to optimise engine cooling and coolant flow:

In reference to above flow analysis, achieving greatly improved cooling around hottest parts of engine:

--------------------------------------

For reference in quotes:

Erhard Milch - Field Marschall, Secretary of the RLM (Reich Air Ministry)

Dr Otto Cuno - Engine Department, Erprobungstelle Rechlin (Aeronautical Research & Test Centre including for engines)

Fritx Nallinger - Technical Director of Daimler Benz

Dr.Ing Helmuth Sachse - Head of engine development, RLM (Reich Air Ministry)

Dipl-Ing Wolfram Eisenlohr - Director of Department of Engines and Accessories at RLM (Reich Air Ministry) Technical Office

Friedrich Seewald - Research scientist at the DVL (German Aviation Research Institute)

Dr Lorenz - RLM (Reich Air Ministry)

---------------------------------------

Discussion of chromium plating of exhaust valves on engines as a response to issues with the DB 605 and other engines, a symptom of nickel shortages. Later on... further Nickel supplies are secured and re-allocated to production. Below follows discussion on the DB 603's successful testing and generally much better heat dissipation of its design.

Lessons learnt from DB 605 and applied to the DB 603 (timing sequencing altered) to ensure superior cooling:

Completion of lessons learned and technical solutions applied to DB 603 in advance of production:

DB 603 engine programme - Daimler Benz experience and DB603 being low risk for production.

I think to summarise here, there's enough evidence to indicate the DB 603 A was (at least) capable of 5 minutes emergency power. Arguably, the lack of an explicit/hard limit with outlet temperature being the limiting factor suggests that depending on the mode/regime of flight (climb, dive etc and lower/higher airflow effect on internal operating temperatures) that this could be exceeded in certain cases depending on the circumstances.

It's quite clear the DB 603 was more resilient and able to achieve better cooling than many other engines the Germans had been building including the DB 605 (even if the DB603's large size, weight and lack of novelty features were unremarkable). The result is it was able to reach and exceed the emergency power timings compared to their previous engines, many of which had been limited to 3 minutes... fundamentally this allowed pilots to exploit this emergency power in a more flexible way.

The circled text in blue in the table I provided on my first post here states a maximum of 10 mins for outlet temperatures but implies that use of such (additional) time is only safe if coolant and water temperatures are not being exceeded. For simplicity sake in game... this could just be set to 5 minutes as a simplification and I think that would be a great compromise. That alone would be a major improvement from the very limited 1 minute we have in game.

And as a general final point for interest, following the political commentary and blame game that was going on internally with regards to the troubled state of engine developments (especially BMW 801, DB 605) in Germany, Calum neatly summarises:

Spoiler

Edited January 27 by Aurora_Stealth
Removed duplicated names from references, added clarity to the summary

January 27

Could I kindly request a formal review of this thread from the team @LukeFF and if acceptable, could a change be considered/scheduled for a future update?

January 27

2 hours ago, Aurora_Stealth said:

Could I kindly request a formal review of this thread from the team @LukeFF and if acceptable, could a change be considered/scheduled for a future update?

I've forwarded it to our engineers to look at, thanks. 🙂

March 13

Hey @LukeFF any chance of a status update or feedback from the engineers regarding this topic?

March 13

I'll see what I can find out. 🙂

March 15

@LukeFF

any chance the La-5fn (m-82fn) engine timers get corrected?

as it probably will have a prominent role in the upcomming Korea Titel (I know different game), it should be on par with the historical correct data

March 15

They've said they're moving away from timers in Korea+. Let that evil be quarantined in BoX, and leave Korea out of this.

April 24

Would it be possible to have this included as well, together with the Spitfire MkV timer?

May 17

On 3/13/2025 at 5:47 AM, LukeFF said:

I'll see what I can find out. 🙂

Hi @LukeFF

I know the team are probably very busy preparing early access for the Siege and Liberation module but is there a possibility this topic/research could be reviewed soon after?

If you need any further details let me know.

Aurora

May 19

That would be for Gavrick to answer. Will ask.

June 30

On 1/17/2025 at 4:47 AM, Aurora_Stealth said:

The later DB 603 G (and A with MW50) versions of these engines (not ingame) appear to be capable of up to 10 minutes emergency power

Were these engines ever installed in the Me410? What other planes were they used in?

I've always loved the idea of a Me410, or Bf110G with MW50.

I think my dream Bf110 would have two DB605DC engines, with an option to remove the rear gun, gunner and everything associated with it for weight reduction.

June 30

14 hours ago, FeuerFliegen said:

Were these engines ever installed in the Me410? What other planes were they used in?

I've always loved the idea of a Me410, or Bf110G with MW50.

I think my dream Bf110 would have two DB605DC engines, with an option to remove the rear gun, gunner and everything associated with it for weight reduction.

From what I understand, only about 10 or so DB603 G were produced. So these only saw use on test or experimental aircraft, but I believe that included trials on a handful of Me 410 B, some of these trials also included MW50. This was late in 1944, so by this time the 410 was starting to be withdrawn from service anyway.

The He 219 night fighter and the Do-335 were also tested with the DB603 G.

I don't think the Bf 110 was tested with it, seeing as the 410 was originally hoped to be the successor to it. In either case this engine was likely too large for that airframe in both weight and size.

So no serial production of these installations from what I've seen on either aircraft. One key drawback is that adding the MW 50 does add a weight penalty so that may have only compounded the existing issues on maneoverability with only a modest performance gain. Then again, I do get the attraction of extracting more output with the very likeable Bf 110 airframe.

July 1

9 hours ago, Aurora_Stealth said:

From what I understand, only about 10 or so DB603 G were produced. So these only saw use on test or experimental aircraft, but I believe that included trials on a handful of Me 410 B, some of these trials also included MW50. This was late in 1944, so by this time the 410 was starting to be withdrawn from service anyway.

The He 219 night fighter and the Do-335 were also tested with the DB603 G.

I don't think the Bf 110 was tested with it, seeing as the 410 was originally hoped to be the successor to it. In either case this engine was likely too large for that airframe in both weight and size.

So no serial production of these installations from what I've seen on either aircraft. One key drawback is that adding the MW 50 does add a weight penalty so that may have only compounded the existing issues on maneoverability with only a modest performance gain. Then again, I do get the attraction of extracting more output with the very likeable Bf 110 airframe.

Thanks for the info.

What is the difference with the DB603G vs the DB603A? (other than some having MW50)

July 6

On 7/1/2025 at 10:05 AM, FeuerFliegen said:

Thanks for the info.

What is the difference with the DB603G vs the DB603A? (other than some having MW50)

Essentially an increased compression ratio with engine optimised for C3 fuel use. Increased takeoff power by about 150 PS.

July 12

Though I have not seen any manual thus far that give any time limits to the DB603

I would recommend to keep it in rhythm with the other german time limits of

3 Start&Notleistung

30 Kampf&Steigleistung

Dauerleistung

even though the DB603 is a different built (more robust) than the DB605, the germans seem to be very conservative with their time limits in contrast to the soviet limits (and that does not necessarily reflect the real time it could be used)

July 12

7 hours ago, the_emperor said:

Though I have not seen any manual thus far that give any time limits to the DB603

I would recommend to keep it in rhythm with the other german time limits of

3 Start&Notleistung

30 Kampf&Steigleistung

Dauerleistung

even though the DB603 is a different built (more robust) than the DB605, the germans seem to be very conservative with their time limits in contrast to the soviet limits (and that does not necessarily reflect the real time it could be used)

I get why it's tempting to follow the same pattern as applied to other Luftwaffe aircraft, but I still think we should consider the evidence we have and the timeline.

They were conservative because they experienced failures in service, which was most prominent with the DB605's but affected many of their engines due to materials shortages as well as cooling design issues including radiator design. As the book I quoted earlier mentions, this affected reliability which the Germans had to compensate for. This notably included significant flaws within the DB605's oil cooling system.

No such issue was reported with the DB603, not during testing or operational use and the lack of any hard time limit being specified is proof of that. I haven't come across any service limitations either which is telling. The Me410 had considerably better radiator and cooling systems than previous aircraft and was reported to be more reliable at high speeds and high power.

My general thought here is that 1 minute WEP was typically used for lower performance engines, or those that couldn't sustain sufficient cooling effect or alternately for those which reliability may be more important (e.g. many earlier bomber engines i.e. takeoff use only).

The 3 minute limitation seems to be used more broadly following the reliability issues experienced from material shortages which is talked about in Calum's book. 10 min WEP seems to be typically reserved for when MW-50 was used to assist cooling.

The DB603 seems to sit in its own category in this regard, mainly because it was introduced somewhat later when all of the above had already been thoroughly experienced and efforts were made to prevent and verify the same issues did not reoccur. It seems to me that 5 minute ratings were tested and aimed for in high performance aero engines including in Germany, but that due to their technical issues they got de-rated. I don't see the same issue here with this engine, so why de-rate it.

Edited July 12 by Aurora_Stealth

July 20

Hi @Gavrick

Sorry to bother you - I understand the team has a lot of focus on Korea, as well as the upcoming Siege and Liberation releases.

However, could we kindly request a review of the engine timer for the Me410 to be scheduled. I think there's substantial evidence in this thread to support revising the WEP engine timer to 5 mins for the DB603A, this engine appears to have been much less impacted by the reliability issues that plagued other aero engines in Germany.

While the Me410 has some very unique systems and cockpit layout which is compelling, ingame players are struggling to achieve any substantial practical performance advantage over the Bf 110 G due to the severely limited (1 min) WEP time. This undermines it's historic function as a 'schnellbomber' or fast strike aircraft (or even as a heavy fighter compared to it), because it can't really sustain it's maximum acceleration for long enough to achieve its superior speed(s) when it needs to get in and out of trouble.

Revising this engine's WEP timer would finally allow players to exploit the Me410's historically superior acceleration, speed, zoom climb and diving performance to engage and escape situations with greater energy and survivability over it's predecessor the Bf 110 G.

It would also improve the climb rate/time substantially for getting to altitude.

Best regards,

Aurora

Edited July 20 by Aurora_Stealth

July 31

110G has 3 min module, no?

August 1

the 5min limit seems to bee resonable.

the Late DB605A(S) where allowed for 10min of 1.42ata

many thanks to @MDzmitry

August 1

31 минуту назад, the_emperor сказал:

the 5min limit seems to bee resonable.

the Late DB605A(S) where allowed for 10min of 1.42ata

many thanks to @MDzmitry

That's a late 1944 document though, keep that in mind. Planes as they are in Il-2 still need some kind of chronological consistency. That is if you're pushing for a better-running 110G, which is still a 1943 plane. Not sure if there are any 110s flying in Normandy or Bodenplatte, but if there are then you could argue to have a 1944 engine upgrade for them.

Don't see how it could correlate with the topic here (DB 603) though, besides speculation.

August 1

On 7/31/2025 at 8:42 PM, Roland_HUNter said:

110G has 3 min module, no?

3 mins can be selected as a modification for 1943 onwards for the Bf 110 G yes.

However the point of this topic is why the Me410, that uses a more reliable engine (DB603 not DB605) and requires no field modifications to begin with... is limited to only 1 min WEP.

3 hours ago, the_emperor said:

the 5min limit seems to bee resonable.

the Late DB605A(S) where allowed for 10min of 1.42ata

many thanks to @MDzmitry

Thanks to both of you. While the document is referring to the smaller DB605, it does further reinforce that 5 and 10min settings were both being used (even without MW50) for less reliable engines than those used in the Me410 (even if late in 1944).

Seeing as the DB603 engine manual posted at the start of the thread states up to 10mins max depending on temperature and conditions, I think therefore 5 mins as an ingame WEP limit is very reasonable and practical even for 1943 (when the aircraft was introduced).

Edited August 1 by Aurora_Stealth

August 2

5 hours ago, Aurora_Stealth said:

up to 10mins max depending on temperature and conditions

it at least defines "kurzzeitig" (short duration) as 10min...and all other manuals allow 1.4ata also for "kurzzeitig"

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Correcting the DB 603A (Me 410) 1.4 ATA Start & Notleistung (WEP) timer from 1 min -> 5 min

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