Possible discrepancy Spitfire engine limits

[Talisman]

Hi Folks and IL2 Development Team,

 

Please help if you can.  I have a hard copy of the Spitfire V pilot notes, AP 1565 and 2280, see link below: 

http://www.avialogs.com/en/aircraft/uk/supermarine/spitfire/ap-1565e-pilots-notes-spitfire-vavb-and-vc.html

 

I have just started flying the Spitfire and am following the pilot notes very closely, but I have found what appears to me to be a discrepancy with the IL2 Spitfire V engine modelling when compared to the official historical Air Publication limits.

 

The Spitfire V pilots notes clearly state the following:

 

COMBAT

5 MINS LIMIT 3,000 Rpm Boost +16

 

It then goes on to say in the note (b) underneath that "Combat boost is permitted only at 2,850 to 3,000 rpm."

 

However, the problem I am finding is that, although I keep engine coolant and oil temperature within limits, my engine keeps suffering critical damage after 5 minutes even when I set 2,850 rpm and use boost + 16. 

 

Something appears to be wrong to me, since there is no 5 minute limit stated in the pilot notes for 2,850 rpm.

 

Am I missing something?

 

Is this a known bug?

 

Is anyone else able to use +16 Boost @ 2,850 rpm for more than 5 minutes without engine damage, when keeping engine oil and coolant within limits?

 

Please keep any replies focused on the Spitfire, the Merlin engine and the appropriate Air Publications, as I would not want this topic to be confused with references to other unrelated aircraft types.

 

Happy landings,

 

56RAF_Talisman

 

 

[ZachariasX]

Seems the devs went again „by the manual“, and when it says 5 min is the limit, the 5 minutes is the limit. Seems the timer interprets 2850 rpm as some sort of emergency rating as well.

 

Tech chat also says nervous things if you keep rpm that high. I never use higher rpm than 2600, except fot take off and landings. Much safer that way (also from judging what technichat says) and you still have a very useful aircraft.

[Panthera]

Seems the devs went again „by the manual“, and when it says 5 min is the limit, the 5 minutes is the limit. Seems the timer interprets 2850 rpm as some sort of emergency rating as well.

 

Tech chat also says nervous things if you keep rpm that high. I never use higher rpm than 2600, except fot take off and landings. Much safer that way (also from judging what technichat says) and you still have a very useful aircraft.

 

2600 rpm at +16 boost doesn't sound like a good idea, generally you want to keep the RPM within 2,850-3,000 rpm at that boost rating.

[=TBAS=Sshadow14]

To low RPM and To High boost.

Number 1 way to cause engine damage,
max boost partial throttle.

[Panthera]

As pr. the evidence I've seen there was a 5 min limit for +9 boost and a 3 min limit for +16 boost.

Edited February 3, 2018 by Panthera

[ZachariasX]

2600 rpm at +16 boost doesn't sound like a good idea, generally you want to keep the RPM within 2,850-3,000 rpm at that boost rating.

I know. I wouldn‘t do that in the real world, but „underrevving“ doesn‘t get punished in this game. So it is just for (current) game mechanics sake. He wanted an engine that doesn‘t quit. Like that, it does less so in the game.

To low RPM and To High boost.

Number 1 way to cause engine damage,

max boost partial throttle.

As of now, not in this game. The devs are aware of it and if we continue to buy their offerings, I‘m positive they will fix this non-trivial issue reasonably.

[-=PHX=-SuperEtendard]

In the ingame specs 2850 RPM and +9 is the 30 min Combat Power.

I think it was in ww2 aircraft performance where I read for the Spit Mk V 3000 RPM at +12 as 5 min limit, and 3000 RPM at +16 as 3 min, if i'm correct this is how it's implemented in the game. When testing the time limits if they are greater than 1 min you should do several tests, as there is some randomization and the higher the time limit the higher is the variance.

(For example when testing 1.37 ata at 2700 RPM in the 109 F-4, I got from 4 mins up to 9 mins, it can be quite variable).

 

2850 RPM and +16 might trigger the min timer with a slight modifier because you are using lower RPMs. At those RPM you could try +12 for example and it should be more than 5 mins (as it would be 5 mins at 3000 RPM already).

 

never use higher rpm than 2600, except fot take off and landings. Much safer that way (also from judging what technichat says) and you still have a very useful aircraft.

 

With only 2600 as max you would be missing a good bit of power, besides the possibility of damage at high boost (although it isn't implemented). You can use 2850 and +9 for climbing or being in the combat zone, as it has a 30 min limit. For general combat you can use full rpm and +12 boost with 5 mins + randomization it should be enough for most encounters.

Edited February 3, 2018 by -=PHX=-SuperEtendard

[Panthera]

In the ingame specs 2850 RPM and +9 is the 30 min Combat Power.

 

I think it was in ww2 aircraft performance where I read for the Spit Mk V 3000 RPM at +12 as 5 min limit, and 3000 RPM at +16 as 3 min, if i'm correct this is how it's implemented in the game. When testing the time limits if they are greater than 1 min you should do several tests, as there is some randomization and the higher the time limit the higher is the variance.

 

(For example when testing 1.37 ata at 2700 RPM in the 109 F-4, I got from 4 mins up to 9 mins, it can be quite variable).

 

2850 RPM and +16 might trigger the min timer with a slight modifier because you are using lower RPMs. At those RPM you could try +12 for example and it should be more than 5 mins (as it would be 5 mins at 3000 RPM already).

 

 

With only 2600 as max you would be missing a good bit of power, besides the possibility of damage at high boost. You can use 2850 and +9 for climbing or being in the combat zone, as it has a 30 min limit. For general combat you can use full rpm and +12 boost with 5 mins + randomization it should be enough for most encounters.

 

Here it notes 5 min for +9 boost:

http://www.spitfireperformance.com/aa878.html

[-=PHX=-SuperEtendard]

Here it notes 5 min for +9 boost:

http://www.spitfireperformance.com/aa878.html

I think it means the 5 mins at +9 would be with at 3000 RPM, as both would be for "max out level flight", and then +9 at 2850 RPM as 1 hour "for climbing"? It's a bit confusing tbh

 

 

Will test the in game time limits at 3000 RPM and +9 to see how they implemented it

Edited February 3, 2018 by -=PHX=-SuperEtendard

[-=PHX=-SuperEtendard]

I tested +9 boost at 3000 RPM ten times, these were the times until engine damage:

7:31
7:18
7:23
6:01
6:34
6:33
6:32
6:47
6:22
6:55

It is more consistent than my previous test of the 109. I guess the limit would be around 5 mins and then you have an extra random time... which would be a bit less than 50% of the original time limit.

I don't recommend this lowish boost at high RPM setting... top speed at the deck was like 455 km/h xD

Edited February 4, 2018 by -=PHX=-SuperEtendard

[unreasonable]

Hi Folks and IL2 Development Team,

 

Please help if you can.  I have a hard copy of the Spitfire V pilot notes, AP 1565 and 2280, see link below: 

http://www.avialogs.com/en/aircraft/uk/supermarine/spitfire/ap-1565e-pilots-notes-spitfire-vavb-and-vc.html

 

I have just started flying the Spitfire and am following the pilot notes very closely, but I have found what appears to me to be a discrepancy with the IL2 Spitfire V engine modelling when compared to the official historical Air Publication limits.

 

The Spitfire V pilots notes clearly state the following:

 

COMBAT

5 MINS LIMIT 3,000 Rpm Boost +16

 

It then goes on to say in the note (b) underneath that "Combat boost is permitted only at 2,850 to 3,000 rpm."

 

However, the problem I am finding is that, although I keep engine coolant and oil temperature within limits, my engine keeps suffering critical damage after 5 minutes even when I set 2,850 rpm and use boost + 16. 

 

Something appears to be wrong to me, since there is no 5 minute limit stated in the pilot notes for 2,850 rpm.

 

Am I missing something?

 

Is this a known bug?

 

Is anyone else able to use +16 Boost @ 2,850 rpm for more than 5 minutes without engine damage, when keeping engine oil and coolant within limits?

 

Please keep any replies focused on the Spitfire, the Merlin engine and the appropriate Air Publications, as I would not want this topic to be confused with references to other unrelated aircraft types.

 

Happy landings,

 

56RAF_Talisman

 

I have those notes too - I think you are misinterpreting them if you think that +16 is not limited to 5 minutes if rpm is 2850.

 

I read them as meaning if you are at +16 you have 5 minutes. If you are at +16 you must have 2850-3000 rpm. i.e. if both these conditions should apply.  The 5 minutes limit for +16 at 2850 is therefore correct according to the PN as I read it.  What I do not know is if you get damage if you run +16 at rpms below 2850 which I think the engine experts agree think you should.

 

Same notes, same table: Max climbing, 1 hr, +9, 2850 rpm. In game the limit is "International power" +9, 2850, 30 minutes.  Not sure why there is a difference here (Soviet internal recommendation, a different set of British recommendations, or the team just guessed?) but it is not critical IMHO.  

[ZachariasX]

With only 2600 as max you would be missing a good bit of power, besides the possibility of damage at high boost (although it isn't implemented). You can use 2850 and +9 for climbing or being in the combat zone, as it has a 30 min limit. For general combat you can use full rpm and +12 boost with 5 mins + randomization it should be enough for most encounters.

 

At 300 m on Autolevel, I get on the HUD:

 

+12 boost

 

293 mph @ 3000 rpm        "full power"

292 mph @ 2800 rpm         -> ~1 % power loss

292 mph @ 2600 rpm         -> ~1 % power loss

286 mph @ 2400 rpm         -> ~7.5% power loss

 

+16 boost

 

311 mph @ 3000 rpm        "full power"

311 mph @ 2800 rpm         -> 0 % power loss

306 mph @ 2600 rpm         -> ~5 % power loss

299 mph @ 2400 rpm         -> ~12.5% power loss

 

Default Spit in quick mission, 100% fuel.

 

 

You can see, the game is rather tolerant to low rpm *to a point*. Less so on +16 lbs boost than +12 boost.

 

2700 rpm is just outside the timer, and power loss are small. But it can already keep you very safe, just when you're working the throttle in a dogfight. 2600 rpm is the lower limit where this play works. If you don't use the HUD, you want to have some margin to play with the revs. For myself, I find that sweetspot between 2600 and 2800.

 

Like this, it is easy to recover the timer, just back the throttle and technochat sets you "in the green" again. If you are at or above 2850 rpm, the timer is on, even if you are throttling back. This means in a skirmish, you always have to perform two operations, one is throttle back and along with that is revving back, to get the timer "off". At 2700 or so (it gives you a bit of a margin on the dial if you have HUD off) you know then, that the timer is only on when your throttle lever is very much forward (or boost lever flipped).

 

If you really need to squeeze the last horse out of your Merlin (say, you're chasing a 109 F4 in a fast climb) then, sure, rev up. But for the rest I find the loss not that big of a deal, with the upside you never reaching 5 min timer.

 

And yes, I wouldn't treat my Spit that way if I owned a real one.

Edited February 4, 2018 by ZachariasX

[Higaluto]

At 300 m on Autolevel, I get on the HUD:

 

+12 boost

 

293 mph @ 3000 rpm        "full power"

292 mph @ 2800 rpm         -> ~1 % power loss

292 mph @ 2600 rpm         -> ~1 % power loss

286 mph @ 2400 rpm         -> ~7.5% power loss

 

+16 boost

 

311 mph @ 3000 rpm        "full power"

311 mph @ 2800 rpm         -> 0 % power loss

306 mph @ 2600 rpm         -> ~5 % power loss

299 mph @ 2400 rpm         -> ~12.5% power loss

 

Default Spit in quick mission, 100% fuel.

 

 

You can see, the game is rather tolerant to low rpm *to a point*. Less so on +16 lbs boost than +12 boost.

 

2700 rpm is just outside the timer, and power loss are small. But it can already keep you very safe, just when you're working the throttle in a dogfight. 2600 rpm is the lower limit where this play works. If you don't use the HUD, you want to have some margin to play with the revs. For myself, I find that sweetspot between 2600 and 2800.

 

Like this, it is easy to recover the timer, just back the throttle and technochat sets you "in the green" again. If you are at or above 2850 rpm, the timer is on, even if you are throttling back. This means in a skirmish, you always have to perform two operations, one is throttle back and along with that is revving back, to get the timer "off". At 2700 or so (it gives you a bit of a margin on the dial if you have HUD off) you know then, that the timer is only on when your throttle lever is very much forward (or boost lever flipped).

 

If you really need to squeeze the last horse out of your Merlin (say, you're chasing a 109 F4 in a fast climb) then, sure, rev up. But for the rest I find the loss not that big of a deal, with the upside you never reaching 5 min timer.

 

 

And yes, I wouldn't treat my Spit that way if I owned a real one.

 

But 2850rpm and +9boost is on a 30min timer. So no problem flying at this setting. For my comfort i bind rpm and throttle to same axis and when both are on 85-90% you have theese settings, depends on altitude. Dont know if this is such a good idea performance wise but alot easier flying. I never go over 90% unless i use boost.

 

And on 3000rpm +16boost you get 18.5ms climb rate at SL could this be correct? those numbers i took out from real spitfire mark 5 charts on google search.

[Talisman]

In the ingame specs 2850 RPM and +9 is the 30 min Combat Power.

 

I think it was in ww2 aircraft performance where I read for the Spit Mk V 3000 RPM at +12 as 5 min limit, and 3000 RPM at +16 as 3 min, if i'm correct this is how it's implemented in the game. When testing the time limits if they are greater than 1 min you should do several tests, as there is some randomization and the higher the time limit the higher is the variance.

 

(For example when testing 1.37 ata at 2700 RPM in the 109 F-4, I got from 4 mins up to 9 mins, it can be quite variable).

 

2850 RPM and +16 might trigger the min timer with a slight modifier because you are using lower RPMs. At those RPM you could try +12 for example and it should be more than 5 mins (as it would be 5 mins at 3000 RPM already).

 

 

With only 2600 as max you would be missing a good bit of power, besides the possibility of damage at high boost (although it isn't implemented). You can use 2850 and +9 for climbing or being in the combat zone, as it has a 30 min limit. For general combat you can use full rpm and +12 boost with 5 mins + randomization it should be enough for most encounters.

 

1.  You say "In the ingame specs 2850 RPM and +9 is the 30 min Combat Power." but can you provide a link to this as I can't find anything like this.  Thanks.

 

2.  You say "2850 RPM and +16 might trigger the min timer with a slight modifier because you are using lower RPMs. At those RPM you could try +12 for example and it should be more than 5 mins (as it would be 5 mins at 3000 RPM already)." and I understand were you are coming from, but the Air Publication pilot notes for the Spit V (as per my link in original post) clearly state that 2850 rpm is permitted at +16lbs boost. 

Further more, I have yet to find any instructions to pilots that there is a time limit for 2850 rpm at +16lbs boost.

 

Happy landings,

 

56RAF_Talisman

[JtD]

If you ever do, try finding one for 2912rpm, and if there isn't, you've found the next bug.

[Talisman]

I have those notes too - I think you are misinterpreting them if you think that +16 is not limited to 5 minutes if rpm is 2850.

 

I read them as meaning if you are at +16 you have 5 minutes. If you are at +16 you must have 2850-3000 rpm. i.e. if both these conditions should apply.  The 5 minutes limit for +16 at 2850 is therefore correct according to the PN as I read it.  What I do not know is if you get damage if you run +16 at rpms below 2850 which I think the engine experts agree think you should.

 

Same notes, same table: Max climbing, 1 hr, +9, 2850 rpm. In game the limit is "International power" +9, 2850, 30 minutes.  Not sure why there is a difference here (Soviet internal recommendation, a different set of British recommendations, or the team just guessed?) but it is not critical IMHO.  

 

The pilot notes are clear, so I do not see that they need to be interpreted.  No interpretation is needed, since the 5 minute limit is clearly stated at 3,000 rpm and +16lbs boost within the stated engine temperature range.

 

Therefore, anything less than the max rpm available (3,000 rpm) is not subject to a time limit.  Otherwise the combat 5 min limit would have stated between 2,850 and 3,000 rpm, which it clearly does not. 

 

You say "Same notes, same table: Max climbing, 1 hr, +9, 2850 rpm. In game the limit is "International power" +9, 2850, 30 minutes." but this is clearly in relation to a 1 hour maximum climbing limit, bearing in mind that in a long climb speeds can be low (less cooling) and engine temperature limits are difficult to maintain.  Climbing out regime limits are a little different to combat.

 

​Still can't find any instruction to pilots regarding a time limit under 3,000 rpm at +16lbs boost.

 

​Happy landings,

 

​56RAF_Talisman

[JtD]

Are you aware that lower rpm at high boost are more critical to the engine than high rpm?

[Talisman]

If you ever do, try finding one for 2912rpm, and if there isn't, you've found the next bug.

 

Bingo, there appears to be no instructions for a time limit under max throttle 3,000 rpm.  Therefore, it would appear that RPM is the critical factor at max boost. 

 

Happy landings,

 

56RAF_Talisman

Are you aware that lower rpm at high boost are more critical to the engine than high rpm?

 

Air publication notes inform the pilot that rpm down to 2,850 is permitted at +16 lbs in this instance.

 

Happy landings,

 

56RAF_Talisman

[Talisman]

Here it notes 5 min for +9 boost:

http://www.spitfireperformance.com/aa878.html

I could be reading this wrong, but they appear to be setting out the parameters for the test and the 2,850 rpm is in relation to the 1 hour climbing test at normal rating +9 lbs boost,

 

 

bearing in mind that in a long climb speeds can be low (less cooling) and engine temperature limits are difficult to maintain.  Climbing out regime limits are a little different to combat.

 

​Still can't find any instruction to pilots regarding a time limit under 3,000 rpm at +16lbs boost.

 

Happy landings,

 

56RAF_Talisman

[JtD]

Air publication notes inform the pilot that rpm down to 2,850 is permitted at +16 lbs in this instance.

And are you aware that this is more critical than 3000rpm?

Edited February 4, 2018 by JtD

[Talisman]

But 2850rpm and +9boost is on a 30min timer. So no problem flying at this setting. For my comfort i bind rpm and throttle to same axis and when both are on 85-90% you have theese settings, depends on altitude. Dont know if this is such a good idea performance wise but alot easier flying. I never go over 90% unless i use boost.

 

And on 3000rpm +16boost you get 18.5ms climb rate at SL could this be correct? those numbers i took out from real spitfire mark 5 charts on google search.

 

"2850rpm and +9boost is on a 30min timer".  Thanks for letting me know, that is a surprise!  Is that definitely correct?  The pilots notes indicate that 2,850 rpm at +9 lbs is for a CLIMBING regime, not general flying and combat at higher air speeds and good engine cooling.

bearing in mind that in a long climb speeds can be low (nose up and less cooling) and engine temperature limits are difficult to maintain.  Climbing out regime limits are a little different to combat.​

​This engine 'timer' thing is starting to sound a bit odd.  I am starting to doubt the modelling a little bit now.

 

​Happy landings,

 

​56RAF_Talisman

And are you aware that this is more critical than 3000rpm?

 

 

Air publication notes inform the pilot that rpm down to 2,850 is permitted at +16 lbs in this instance.

 

Happy landings,

 

56RAF_Talisman

[unreasonable]

The pilot notes are clear, so I do not see that they need to be interpreted.  No interpretation is needed, since the 5 minute limit is clearly stated at 3,000 rpm and +16lbs boost within the stated engine temperature range.

 

Therefore, anything less than the max rpm available (3,000 rpm) is not subject to a time limit.  Otherwise the combat 5 min limit would have stated between 2,850 and 3,000 rpm, which it clearly does not. 

 

You say "Same notes, same table: Max climbing, 1 hr, +9, 2850 rpm. In game the limit is "International power" +9, 2850, 30 minutes." but this is clearly in relation to a 1 hour maximum climbing limit, bearing in mind that in a long climb speeds can be low (less cooling) and engine temperature limits are difficult to maintain.  Climbing out regime limits are a little different to combat.

 

​Still can't find any instruction to pilots regarding a time limit under 3,000 rpm at +16lbs boost.

 

​Happy landings,

 

​56RAF_Talisman

 

You read it how you like: I have the PN in front of me - it says "Combat 5 mins limit   3,000 (rpm)   +16 (boost)

 

The line for "Combat" is showing the upper limits of each parameter, as they do on every other line.  The upper limit combat boost for rpm is 3,000.  The lower limit for combat boost is 2850, as note: b) below says: "Combat boost is permitted at 2850 to 3000 rpm".

 

Combat boost would also include any boost setting higher than the next setting down - ie Max take off to 1,000ft, 3000 rpm +12. But by your logic, 3,000 rpm at +15 would also not be time limited.

 

Combat boost has a 5 minutes limit. Therefore combat boost at 2850 has a 5 minutes limit.  This seems to me to be clear and obvious.

 

If you think  +16 is OK for more than 5 minutes at 2,999 rpm, go for it - IMHO your conclusion is bizarre and totally at odds with the clear meaning of the PN.

[Talisman]

You read it how you like: I have the PN in front of me - it says "Combat 5 mins limit   3,000 (rpm)   +16 (boost)

 

The line for "Combat" is showing the upper limits of each parameter, as they do on every other line.  The upper limit combat boost for rpm is 3,000.  The lower limit for combat boost is 2850, as note: b) below says: "Combat boost is permitted at 2850 to 3000 rpm".

 

Combat boost would also include any boost setting higher than the next setting down - ie Max take off to 1,000ft, 3000 rpm +12. But by your logic, 3,000 rpm at +15 would also not be time limited.

 

Combat boost has a 5 minutes limit. Therefore combat boost at 2850 has a 5 minutes limit.  This seems to me to be clear and obvious.

 

If you think  +16 is OK for more than 5 minutes at 2,999 rpm, go for it - IMHO your conclusion is bizarre and totally at odds with the clear meaning of the PN.

 

Anything under the stated number for the limit is by default under the limit.  

 

Take off from a standing start and climb to 1,000 ft is a different thing from combat.  Your remark about +15 boost appears a little overheated, so I shan't respond in kind.

 

As for pilot notes, they are to be read in conjunction with Air Publication 2095 Pilot Notes General, which make interesting reading.

 

 https://ww2aircraft.net/forum/threads/ap2095-pilots-notes-general.26671/

 

Happy landings,

 

56RAF_Talisman

[ZachariasX]

But 2850rpm and +9boost is on a 30min timer. So no problem flying at this setting.

 

Setting to +9 boost in the heat of the fight in that silly gauge down there is not that straight forward. My advise for these "game settings" ist that you do not blow your engine while working your throttle (and going to +12, getting at least the same as 3000 rpm and finding throttle position of +9) and looking after the other aircraft rather than at a silly small gauge. No more.

 

Regarding the real engine, as unreasonable stated, I think the PN is very clear about those limits.

Edited February 4, 2018 by ZachariasX

[Higaluto]

"2850rpm and +9boost is on a 30min timer".  Thanks for letting me know, that is a surprise!  Is that definitely correct?  The pilots notes indicate that 2,850 rpm at +9 lbs is for a CLIMBING regime, not general flying and combat at higher air speeds and good engine cooling.

bearing in mind that in a long climb speeds can be low (nose up and less cooling) and engine temperature limits are difficult to maintain.  Climbing out regime limits are a little different to combat.​

​This engine 'timer' thing is starting to sound a bit odd.  I am starting to doubt the modelling a little bit now.

 

​Happy landings,

 

​56RAF_Talisman

 

 

Air publication notes inform the pilot that rpm down to 2,850 is permitted at +16 lbs in this instance.

 

Happy landings,

 

56RAF_Talisman

 

 

it says so right here, says nothing about being in a climbing regime?

 

Engine modes:

Max Cruising power (unlimited time): 2650 RPM, boost +7

International power (up to 30 minutes): 2850 RPM, boost +9

Emergency Max All Out power (up to 5 minutes): 3000 RPM, boost +16

 

and all engines in game is on a sort of a timer, with a random element involved, sometimes you can go over the time limit in WEP other times not so much, as many have tested and figured out (not me)

but after a while you get used to how much you can push your engine. for me at least it works very nice to just use the tekno chat as a reference for engine boost and rpm, never go above 90%, and if i go over 90% its with +16boost in a dogfight, pursuit, steep climbing etc.

 

 

[56RAF_Roblex]

I am not sure if it helps but the pilots notes for the earlier Merlin XII (Air Publication 1565B) quote a 1 hour limit climbing at 2850 & +9.  It also says that 3000rpm can be used for 30 minutes if above 20,000ft though it does not give a boost figure.

[Talisman]

 

"2850rpm and +9boost is on a 30min timer".  Thanks for letting me know, that is a surprise!  Is that definitely correct?  The pilots notes indicate that 2,850 rpm at +9 lbs is for a CLIMBING regime, not general flying and combat at higher air speeds and good engine cooling.

bearing in mind that in a long climb speeds can be low (nose up and less cooling) and engine temperature limits are difficult to maintain.  Climbing out regime limits are a little different to combat.​

​This engine 'timer' thing is starting to sound a bit odd.  I am starting to doubt the modelling a little bit now.

 

​Happy landings,

 

​56RAF_Talisman

 

 

Air publication notes inform the pilot that rpm down to 2,850 is permitted at +16 lbs in this instance.

 

Happy landings,

 

56RAF_Talisman

 

 

it says so right here, says nothing about being in a climbing regime?

 

Engine modes:

Max Cruising power (unlimited time): 2650 RPM, boost +7

International power (up to 30 minutes): 2850 RPM, boost +9

Emergency Max All Out power (up to 5 minutes): 3000 RPM, boost +16

 

and all engines in game is on a sort of a timer, with a random element involved, sometimes you can go over the time limit in WEP other times not so much, as many have tested and figured out (not me)

but after a while you get used to how much you can push your engine. for me at least it works very nice to just use the tekno chat as a reference for engine boost and rpm, never go above 90%, and if i go over 90% its with +16boost in a dogfight, pursuit, steep climbing etc.

 

 

 

 

Thing is I can't find that in the real life pilot notes I linked to in the original post.  So what is the original reference for this international power?  Also this seems to be talking about an engine 'mode' and not an engine 'limitation'.

 

Happy landings,

 

56RAF_Talisman

Edited February 4, 2018 by 56RAF_Talisman

[Talisman]

And are you aware that this is more critical than 3000rpm?

 

OK JtD, I think I see what you are saying.  But a small decrease in rpm, within permitted rpm rang at +16 lbs boost surely is not going to increase stress enough to a critical level, when you consider there will be some relief from the prop turning so many times, less drag, and cooling from a fast moving aircraft.  Yes, it would be different if turning in a tight dogfight at reduced airspeed or climbing too steep for to long and bleeding airspeed.  I am just concerned that this timer thing, as currently modelled, is a bit too crude.

 

Perhaps a better method would be to link engine damage to flying too slow for too long at high combat settings.  At least that would make more sense to me.  Then I would know what is being modelled as breaking, because it would be due to overheating.  But as it is at the moment I don't understand what is being modelled as breaking because it just seems arbitrary and crude on a timer that is not like a real warbird engine simulation.

 

Happy landings,

 

56RAF_Talisman

Edited February 4, 2018 by 56RAF_Talisman

[HR_Zunzun]

OK JtD, I think I see what you are saying.  But a small decrease in rpm, within permitted rpm rang at +16 lbs boost surely is not going to increase stress enough to a critical level, when you consider there will be some relief from the prop turning so many times, less drag, and cooling from a fast moving aircraft.  Yes, it would be different if turning in a tight dogfight at reduced airspeed or climbing too steep for to long and bleeding airspeed.  I am just concerned that this timer thing, as currently modelled, is a bit too crude.

 

Perhaps a better method would be to link engine damage to flying too slow for too long at high combat settings.  At least that would make more sense to me.  Then I would know what is being modelled as breaking, because it would be due to overheating.  But as it is at the moment I don't understand what is being modelled as breaking because it just seems arbitrary and crude on a timer that is not like a real warbird engine simulation.

 

Happy landings,

 

56RAF_Talisman

 

 

I think that the way is modelled in DCS. At least the spit. You hang on your prop at full throttle and it will cook in very short time. Seem to work on an overheating basis.

[303_Kwiatek]

I am not sure if it helps but the pilots notes for the earlier Merlin XII (Air Publication 1565B) quote a 1 hour limit climbing at 2850 & +9.  It also says that 3000rpm can be used for 30 minutes if above 20,000ft though it does not give a boost figure.

 

For SPitfire MKV  engine mode +9 and 2850 RPM is also 1 hr limit -  from original manual.

 

In game is error and these mode is only 1/2 hr limit

 

Engine modes:

Max Cruising power (unlimited time): 2650 RPM, boost +7

International power (up to 30 minutes): 2850 RPM, boost +9

Emergency Max All Out power (up to 5 minutes): 3000 RPM, boost +16

Edited February 5, 2018 by 303_Kwiatek

[Talisman]

For SPitfire MKV  engine mode +9 and 2850 RPM is also 1 hr limit -  from original manual.

 

In game is error and these mode is only 1/2 hr limit

 

Engine modes:

Max Cruising power (unlimited time): 2650 RPM, boost +7

International power (up to 30 minutes): 2850 RPM, boost +9

Emergency Max All Out power (up to 5 minutes): 3000 RPM, boost +16

 

Yes Kwiatek, and in the original source manual the 2850 rpm at +9 lbs boost is clearly stated as the max 1 hour CLIMBING limit, not a general flying or combat limit, but a climb regime.

Further more, the original manual gives speeds (IAS) for maximum rate of climb ranging from 170 mph up to 10,000 feet, down to 115 mph above 37,000 feet.

 

If the IL-2 developers have put a half hour timer on 2850 rpm at +9 lbs boost for level flight and general flying at high speed (not climbing) then that would appear to be a mistake.  I must emphasise that I don't know if they have done that because I have not tested that personally; however, there is a post above from someone who says there is a timer.

Happy landings,

 

56RAF_Talisman  

[unreasonable]

Yes Kwiatek, and in the original source manual the 2850 rpm at +9 lbs boost is clearly stated as the max 1 hour CLIMBING limit, not a general flying or combat limit, but a climb regime.

Further more, the original manual gives speeds (IAS) for maximum rate of climb ranging from 170 mph up to 10,000 feet, down to 115 mph above 37,000 feet.

 

If the IL-2 developers have put a half hour timer on 2850 rpm at +9 lbs boost for level flight and general flying at high speed (not climbing) then that would appear to be a mistake.  I must emphasise that I don't know if they have done that because I have not tested that personally; however, there is a post above from someone who says there is a timer.

Happy landings,

 

56RAF_Talisman  

 

Well at the risk of irritating you again, I think you are wrong about that (that it is a mistake to limit 2850 +9 for general flight) as the PN says in the same table:

 

Max rich    continuous    2650 +7

Max weak continuous    2650 +4

 

If you were intended to use 2850 +9 continuously without a limit would the PN not have said so? They do not.

 

BTW - the game interpretation of limits as a timer for damage I agree is a regrettable simplification which with luck will get replaced by a more sophisticated model. But given what it is, the Spitfire limits are consistent with the notes - with the exception of the 30min vs 1 hour issue. I do not recall if the team mentioned where they got that from. 

[Talisman]

Further examination of the original source pilot notes (link provided in the original post) states at paragraph 10, GENERAL FLYING, sub paragraph (iv) that:

 

"For combat manoeuvres climbing rpm should be used".

 

Guess what climbing rpm is stated in the original source pilot notes at paragraph 1, yes, 2850 rpm.

 

​So, in summary, the original pilot notes allow a combat setting of 2850 rpm to be used with +16 lbs boost, the pilot notes also say that 2850 rpm should be used for combat manoeuvres and the pilot notes say nothing of a 5 minute combat limit for +16 lbs boost at 2850 rpm.

 

Happy landings,

 

56RAF_Talisman 

[unreasonable]

Further examination of the original source pilot notes (link provided in the original post) states at paragraph 10, GENERAL FLYING, sub paragraph (iv) that:

 

"For combat manoeuvres climbing rpm should be used".

 

Guess what climbing rpm is stated in the original source pilot notes at paragraph 1, yes, 2850 rpm.

 

​So, in summary, the original pilot notes allow a combat setting of 2850 rpm to be used with +16 lbs boost, the pilot notes also say that 2850 rpm should be used for combat manoeuvres and the pilot notes say nothing of a 5 minute combat limit for +16 lbs boost at 2850 rpm.

 

Happy landings,

 

56RAF_Talisman 

 

They explicitly say this, it just means reading more than one line at a time.  Combat boost limits are given as +16, 3000rpm, 5 minutes: from the table.  Combat boost is only permitted between 2850 and 3000rp: from note b) to the table.   Note a)+16....obtained by operating the boost control cut out. 

 

It is obvious that the writers of the PN intended that any time the boost control cut out was used with the throttle forwards, (the only way to get +16), you were operating in "combat boost".  Which is always time limited. Once you are in combat boost, you watch your rpm limits. rpm does not define what is or is not combat boost - that is done by the boost number, strangely enough.

 

"For climbing manoeuvres climbing rpm should be used" is not inconsistent with any of this, since climbing rpm is given as 2850 and the combat boost is allowed at 2850.  You do not have to make combat manouevres at combat boost.  

 

The devs understand this perfectly well.

[Talisman]

Well at the risk of irritating you again, I think you are wrong about that (that it is a mistake to limit 2850 +9 for general flight) as the PN says in the same table:

 

Max rich    continuous    2650 +7

Max weak continuous    2650 +4

 

If you were intended to use 2850 +9 continuously without a limit would the PN not have said so? They do not.

 

BTW - the game interpretation of limits as a timer for damage I agree is a regrettable simplification which with luck will get replaced by a more sophisticated model. But given what it is, the Spitfire limits are consistent with the notes - with the exception of the 30min vs 1 hour issue. I do not recall if the team mentioned where they got that from. 

 

No problems, as I am not irritated, just interested.  I am pleased to be examining the issues with people who share the same interest   I think it's good to have a community like this.  Amongst many other things, it is almost like belonging to an historical society with engineering, physics, and a lot of other things thrown in too.  I am not expert, but I struggle along and enjoy the education.

 

Anyway, back on topic.  To be fair, I did not say the exact words you have attributed to me in your brackets above.

What I actually said was "If the IL-2 developers have put a half hour timer on 2850 rpm at +9 lbs boost for level flight and general flying at high speed (not climbing) then that would appear to be a mistake."  I would have thought that you and others might possibly agree with that.

​So, if we really must accept the IL-2 developers timer modelling scenario, I think it would be much better if the timer was set to at least 1 hour for 2850 rpm and +9 lbs boost, if not a little more if not in a climbing regime.

 

​Yes, you have a point regarding max rich continuous (leaving weak mixture continuous to one side as special circumstance) at 2650 rpm and +7 lbs, but a timer allowance of 1 hour or more for the maximum climbing 1 hour limit at 2850 rpm and +9 lbs need not interfere with that.

 

The problem I have with all this developer timer limited instant engine damage stuff and the understanding of aircraft pilot notes and limits, is that aircraft pilot notes and limits are all too often not read and properly understood in the wider context and in association with AP 2095, Pilots Notes General (link and extract below).  I would encourage everyone to read these notes in full, as well as specific aircraft pilot notes.  Specific aircraft pilot notes are not supposed to be read in isolation.  There is a bigger picture and that is all too often forgotten it seems to me. 

 

https://ww2aircraft.net/forum/threads/ap2095-pilots-notes-general.26671/

 

[Talisman]

They explicitly say this, it just means reading more than one line at a time.  Combat boost limits are given as +16, 3000rpm, 5 minutes: from the table.  Combat boost is only permitted between 2850 and 3000rp: from note b) to the table.   Note a)+16....obtained by operating the boost control cut out. 

 

It is obvious that the writers of the PN intended that any time the boost control cut out was used with the throttle forwards, (the only way to get +16), you were operating in "combat boost".  Which is always time limited. Once you are in combat boost, you watch your rpm limits. rpm does not define what is or is not combat boost - that is done by the boost number, strangely enough.

 

"For climbing manoeuvres climbing rpm should be used" is not inconsistent with any of this, since climbing rpm is given as 2850 and the combat boost is allowed at 2850.  You do not have to make combat manouevres at combat boost.  

 

The devs understand this perfectly well.

 

OK, this is how I see it.  You put forward that it is obvious what the writers intended, but the very fact that you say it this way means that you are having to assume what the writers intended.  And you are having to assume because it does not say what want it to say, or think it should say.  It is simple, you read the table from left to right and there is no 5 minute combat limit for engine output in terms of rpm and boost under 3,000 rpm and +16 boost.  The notes underneath the table indicate that combat boost may be used under 3,000 rpm and down to 2,850, but there is no mention of a 5 minute combat limit under engine output down to 2850 rpm.  Now read Pilot Notes General and put it all into the wider real life perspective.

 

 https://ww2aircraft.net/forum/threads/ap2095-pilots-notes-general.26671/

 

[Sgt_Joch]

 

 

https://ww2aircraft.net/forum/threads/ap2095-pilots-notes-general.26671/

 

 

I think posters read those pilot notes and only see what they want to see. If you read the entire document, especially the preceding page, it is clear they are not saying the 5 minute take off/combat limit is the same as the 1 hour climbing limit, merely giving examples of what "engine limitations" look like in pilot notes.

 

The "Pilot's Notes General" was for pilots of all operational AC, including multi-engine AC and covered general subjects which would apply to all AC.

 

For specific instructions of the engine limitations of a particular AC, a pilot had to consult the Pilot Notes for that particular AC.

Edited February 5, 2018 by Sgt_Joch

[Talisman]

I think posters read those pilot notes and only see what they want to see. If you read the entire document, especially the preceding page, it is clear they are not saying the 5 minute take off/combat limit is the same as the 1 hour climbing limit, merely giving examples of what "engine limitations" look like in pilot notes.

 

The "Pilot's Notes General" was for pilots of all operational AC, including multi-engine AC and covered general subjects which would apply to all AC.

 

For specific instructions of the engine limitations of a particular AC, a pilot had to consult the Pilot Notes for that particular AC.

 

Your say "it is clear they are not saying the 5 minute take off/combat limit is the same as the 1 hour climbing limit," but you lost me there, as I don't know who said that.

 

​Happy landings,

 

​56RAF_Talisman

[Sgt_Joch]

Your say "it is clear they are not saying the 5 minute take off/combat limit is the same as the 1 hour climbing limit," but you lost me there, as I don't know who said that.

 

​Happy landings,

 

​56RAF_Talisman

 

referring to another debate for future reference. sorry.  

 

please carry on.

[unreasonable]

OK, this is how I see it.  You put forward that it is obvious what the writers intended, but the very fact that you say it this way means that you are having to assume what the writers intended.  And you are having to assume because it does not say what want it to say, or think it should say.  It is simple, you read the table from left to right and there is no 5 minute combat limit for engine output in terms of rpm and boost under 3,000 rpm and +16 boost.  The notes underneath the table indicate that combat boost may be used under 3,000 rpm and down to 2,850, but there is no mention of a 5 minute combat limit under engine output down to 2850 rpm.  Now read Pilot Notes General and put it all into the wider real life perspective.

 

 https://ww2aircraft.net/forum/threads/ap2095-pilots-notes-general.26671/

 

 

 

There are three issues here:

 

1) The general modelling of engine limitations in BoX vs the nature of the guidance in RL PNs, flying guides etc.

2) The specific difference between the 30 minutes and one hour "limit" for the Spitfire V

3) Whether 16+ is limited to 5 minutes at 2850.

 

On (1) I think we all agree that it is an unrealistic simplification that has unfortunate consequences in the game. Sadly, having no engine limits arguably has worse consequences.  There might be a better system, but so far most people seem unable to agree what it is. The developers are gradually making the system more complex, so maybe this will get better - or not.

 

On (2) you would have to search Gavrick's posts around the time of the Spitfire release DD's to see if he mentions why 30 minutes was chosen. The fact that the in-game notes mention "international power" suggest that they have a document with this limit in it from somewhere, but this is just my speculation based on the assumption that they tend not to just make stuff up without sources, although they do of course make mistakes from time to time.

 

On (3) we have a real disagreement. My bottom line on this is that when I read the PN it is crystal clear to me that what is being limited by the table is the use of "combat boost".  Not "combat boost at 3000rpm only".  "Combat boost" obtains at anytime that you have engaged the boost over-ride and have boost above the next lowest limit, which is +12 for max take-off, which is limited not by time but up to 1,000 feet (ie a very short time).   2850 is explicitly mentioned as being the lowest permissible rpm at which combat boost may be used. Therefore +16 at 2850 is time limited.

 

"and there is no 5 minute combat limit for engine output in terms of rpm and boost under 3,000 rpm and +16 boost."   Wrong. Every boost setting in that table is limited except for those marked as "continuous".  The highest boost level on that table that is not limited is +7

 

If your reading of the table as a limit for "+16 at 3000rpm only" was correct, then +16 at 2999 would also be time unlimited, as would +15 at 3000. Your interpretation of the table defies common sense.

 

If you really think that the devs have made this mistake, and that I - and the other contributors to the thread who have made the same point - are all wrong, go ahead and PM Han pointing out the error.