La-5fn correct boosted/WEP Time

[the_emperor]

Please review and correct the boosted time for the La-5fn from 10 to 5min.

FM report with all manuals have been already submitted in Nov. 2021:

 

In game the La-5fn engine (Ash-85fn) is rated in boosted mode (WEP) for 10min. This is quite long compared to the German (without additional injection) 3min or western allied 5min.

 

Thus far I have found that most manuals regarding the La-5fn and its engines also state a 5min time limit.

Does any else has seen any more documents than those I list, that state a 10min limit? 

 

I have compiled all primary sources stating the 5min WEP limit for the La-5fn and the ASh-82FN engine sorted from 1943 to 1954 (1943 La-5fn; 1944 La-5fn; 1945 Tu-2 Ash-82fn;1947 La-9 Ash-82fn; 1947 Ash-82fn; 1950 La-11 Ash-82fn; 1954 Ash-82fn).

 

 

Regarding the 10min time limit I have found thus far 2 credible source and one that seems questionable:

a) One source (1945) for the La-7 with M-82fn engine clearly stating 10min ( according to @=FB=VikS qualifies as a typo) and 

b)1943 report on the current state of the soviet aeronautical industry (additionally it seems to be the scource for the inlimted use of the M-82f unlimited boost)-

I figure, this is the report they based the 10min (and unlimited WEP for the La-5f) limit on (as it what used by @=FB=VikS to explain the the Yaks/Lags unlimited time on full boos).

c) one source (1944) for the La-5fn that looks like it has been tempered with and a "5" was converted to a "10" (number no longer centred between words as in other manuals) but it could also be a "15" -> which is therefore to dismiss it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a)La-7

 

 

b) offical report on current state of the aviation engine industry

 

M-82f unlimited use of boost:

 

C) debateable La-5fn pilot notes

 

 

 

 

 

 

 

 

 

 

 

 

 

for those who are not able to directly spot the 5min limits in the manuals, I have highlighted those:

 

Edited May 24, 2024 by the_emperor

[the_emperor]

Any chance to get this at least reviewed and maybe shown other manuals that confirm the 10min limit?

otherwise, acording to @=FB=VikS the 10min limit can be considered a typo and should be corrected. 

(see discussion here: 

 

[the_emperor]

When will this issue get fixed?

Cheers✌️

[MK_RED13]

Yes!!!! When? 

[the_emperor]

for those who are not able to directly spot the 5min limits in the manuals, I have highlighted those:

 

 

 

[the_emperor]

Here is actually a 10min source

though I dont know how credible the source is (as its a report on the current state of the soviet aeronautical engine industry, but to my proletarian eye it looks legit),

this raises the question again, how the devs chose which manual to follow?

 

Edited May 24, 2024 by the_emperor

[the_emperor]

and this report also explains, why the devs chose to give the M-82f Engine for the La-5f unlimited WEP time:

[FTC_ChilliBalls]

On 5/22/2024 at 5:42 PM, the_emperor said:

Here is actually a 10min source

though I dont know how credible the source is (as its a report on the current state of the soviet aeronautical engine industry, but to my proletarian eye it looks legit),

this raises the question again, how the devs chose which manual to follow?

 

Question is whether that ain't the equivalent to Daimler Benz reports which state that the testbench DB605A engine ran at full speed for several hours.

 

On 5/24/2024 at 3:36 PM, the_emperor said:

and this report also explains, why the devs chose to give the M-82f Engine for the La-5f unlimited WEP time:

Is this also the same kind of report or an actual pilot's manual?  

[the_emperor]

26 minutes ago, FTC_ChilliBalls said:

Is this also the same kind of report or an actual pilot's manual?  

Same report. Its labled for official use for engineers/technicians and released by the chief engineer of the red army air force (sounds all legit)
would be nice to know from the devs whether this is the report they based the engine on and dismissed all the other manuals. 

Edited May 27, 2024 by the_emperor

[FTC_ChilliBalls]

4 hours ago, the_emperor said:

Same report. Its labled for official use for engineers/technicians and released by the chief engineer of the red army air force (sounds all legit)
would be nice to know from the devs whether this is the report they based the engine on and dismissed all the other manuals. 

The point I am trying to make is that the limits in game ought to come from similar documents. 

If this is a technical report or an instruction for engine run ins for mechanics, this has about the same value as an industry report on the German side.

 

If the in game limits are based on flight manuals, then these should be applied like for like aside from cases where adhering too closely to the letter doesn't make sense, i.e. with the P51 and Spitfire having 5 and 10 minutes of WEP respectively even though they use the same engine.

Edited May 28, 2024 by FTC_ChilliBalls

[the_emperor]

3 hours ago, FTC_ChilliBalls said:

The point I am trying to make is that the limits in game ought to come from similar documents. 

If this is a technical report or an instruction for engine run ins for mechanics, this has about the same value as an industry report on the German side.

 

Jup, this is the question I would like to raise and get an answer to...which source, report, manual e.g. do the devs follow when deciding on those things?

[the_emperor]

[the_emperor]

On 5/27/2024 at 9:46 PM, FTC_ChilliBalls said:

Question is whether that ain't the equivalent to Daimler Benz reports which state that the testbench DB605A engine ran at full speed for several hours.

 

Is this also the same kind of report or an actual pilot's manual?  

 

Well, it should at least raise some suspicions…. And I hope the devs have more sources to back that up, otherwise being allowed to run WEP with a of max 1750hp for an unlimited amount of time while simultaneously increasing the overhaul time from 100 to 150 hours makes the M-82f the best aero-engine of WW2…..maybe of all times.

silly Brits/Yanks, their Packard/Merlin with the same HP output was only allowed to use that for 5min….

[the_emperor]

any news whether this gets fixed with the advent of the La-7?

[LukeFF]

No, sorry

[MDzmitry]

To be honest I just hope at least La-7 gets 5min WEP. From what I know early series had temperature issues with their engines having uneven cooling and thus worse wear and more failures.

[150_GIAP-Red_Dragon]

19 часов назад, MDzmitry сказал:

To be honest I just hope at least La-7 gets 5min WEP. From what I know early series had temperature issues with their engines having uneven cooling and thus worse wear and more failures.

That is not about wep, its about technical issus, isnt it? Every plane has its own issues, and every plane in this game has technical problem that you can't see in the game there are limits for all of them.

 And don't we read la 7s manual instead of asking for 5 or 1 min or jast 30 sec in case someone think that is right?

Edited July 13 by 150_GIAP-Red_Dragon

[MDzmitry]

1 час назад, 150_GIAP-Red_Dragon сказал:

That is not about wep, its about technical issus, isnt it? Every plane has its own issues, and every plane in this game has technical problem that you can't see in the game there are limits for all of them.

The technical reliability in Il-2 has been portrayed a number of times through WEP time/availability, as with Bf 109 G-2's engine. 

La-5FN is the topic of the debate whether we should believe sources stating WEP of 5 or 10 minutes. La-7 had that same engine, but ended up being less reliable overall due to a variety of reasons. Since La-5FN gets a favourable treatment of 10 minutes of WEP with 0 chances of change, I find it only natural to have La-7 with the other option not to show too much bias.

[150_GIAP-Red_Dragon]

I can see a logical mistake in such approach ..

[the_emperor]

On 7/12/2025 at 6:58 PM, LukeFF said:

No, sorry

Thank you. 
 

On 7/13/2025 at 5:17 PM, MDzmitry said:

La-5FN is the topic of the debate whether we should believe sources stating WEP of 5 or 10 minutes.

Correct. The question is whether based on the sources thus far it should be 5 or 10min.  
 

On 7/13/2025 at 5:17 PM, MDzmitry said:

I find it only natural to have La-7 with the other option not to show too much bias.

Could be a compromise

 

On 7/12/2025 at 9:10 PM, MDzmitry said:

From what I know early series had temperature issues with their engines having uneven cooling and thus worse wear and more failures.

Can recommend some reads on that topic? Sound interesting in comparing the La7 to the La5fn

 

 

[MDzmitry]

13 минут назад, the_emperor сказал:

Can recommend some reads on that topic? Sound interesting in comparing the La7 to the La5fn

My primary source on that topic is the series of Gennadiy Serov's articles on the history and development of M-82 engine and Lavochkin fighters. It's completely in Russian though, so you might have some trouble reading it.

He's biased towards La fighters a bit due to his history of working with the bureau, but the part about La-7 field trials is quite harsh on the plane.
1) Said articles on Google Drive (p.42 for the one dedicated to La-7)
2) Translation of a couple of paragraphs from there are WIP, will be added here asap

Edited July 15 by MDzmitry

[MDzmitry]

Скрытый текст

Translation:
But after the positive evaluation of the plane itself followed a surprisingly negative performance of ASh-82FN engines:
"ASh-82FN engines on La-7 turned out to be unreliable. Primary defects that were found during military tests are:
a) stepwise wear of cylinder liners and piston rings;
b) oil entering the engine intake system;
c) wear of valve stem guides resulting in increased oil consumption".
 

Скрытый текст

Translation:
On the 18th of September 1944 division commander colonel Stalin signed a document that stated the following:
"In the process of using [La-7s] multiple engine failures occurred, which in turn leads to: an increased % of non-operational aircraft, hindering the regiment's performance, and more non-combat losses.
"... the absence of dust filters on most aircraft combined with the low position of air intakes. On some aircraft that had filters installed, the latter became faulty due to backfires. Apart from that, the air damper adjustment is lacking (with gaps of 10-20 mm)".
 

Скрытый текст

Translation:
For the purpose of evaluating the influence of the propeller-motor group on the cylinder wear the air intake and exhaust systems were inspected. It was found out, that on La-7 both the exhaust and the intake took place in worse conditions than on La-5. On La-7 upper and lower exhaust pipes are covered by the cowling and aren't situated in the blower flap airflow, which leads to the exhaust from said pipes to partially hit the anti-fire wall and swirl, which in turn worsens the temperature conditions of the back row cylinders compared to La-5FN, albeit not exceeding the temperature limit stated in the ASh-82FN operational manual.

Скрытый текст

Translation:
Conversing with the pilots and technicians of 32nd and 63rd Guards Regiments, that have been operating La-5FN fighters since 1943 and La-7 since 1944, as well as inspecting the documentation and inspection by the representatives of the factory №19 led to the conclusion, that no deviations were found in regards to following the operational manual, as well as using the correct fuel and oil types.
Besides that it was pointed out, that 137th GIAP (Guards Fighter Regiment) of the same division, operating from the same airfields as 32nd and 63rd GIAPs and being equipped with 13 La-5FN fighters, only experienced 4 cases of cylinder failures in September of 1944. The engine operating time on these fighters averaged 80 hours. (personal note: before it was stated that La-7 engine had to have its cylinders changed after 25-30 hours of operating)

Note: this is only a chronological pace of documents and research, it was later concluded that the problem had more to do with a significant drop in the quality of engines produced by the factory №19. But all of the aforementioned aspects remained and still had a negative impact on the engine reliability.

Here's a bonus: a table on the amount of La-5 and La-7 fighters in the active army (frontline) and rear units as of the 1st of February 1945: table 1 is total, 2 is operational, 3 is non-operational, and 4 is a % of non-operational aircraft.

Скрытый текст

P.S. - sorry if the translation is botched, I did my best

Edited July 15 by MDzmitry

[150_GIAP-Red_Dragon]

Its not about WEP. Clearly , factory fresh la7 has not such limit as 5 min WEP. And problems with cylinders solved by motor replacing. BTW do you know that more hard temperature conditions is modeled for la 5f without any special changing WEP time compare with la5fn in this game.