BF109 Engine Damage in boost/emergency mode

[Stig]

Just like Russian planes would not go 100% all the time. Yet they do in game

 

It was just a general comment. It was not to put any pet conspiracy theories to bed 

[LColony_Kong]

what? No, engines do fail for that reason and the fact you would make that statement just shows you don't have a basic understanding of how internal combustion engines work.

 

Increasing compression ratio through boost generates extra pressure and heat. Both can be enough to cause mechanical failure, but the more common result is pre-detonation of the air-fuel mixture either because the octane level of the fuel is too low or heat is too high. Pre-detonation can easily cause quick destruction of the engine. Even without detonation, excessive heat can easily lead to engine failure.

I know exactly how these engines work, thanks. 

 

You are not understanding the point. Engines can fail at ANY power setting. The scenario you described could very well happen at cruise power or when going to combat, much less emergency. But you are describing nothing more than the fact that mechanical devices can fail. Thanks for noting something we all already know. 

 

What the engine IS NOT doing is failing because you wore it out in 5 minutes plus 1 second. The time to wear the engine out from WEP is measured in HOURS, not minutes. The type of mechanical failures you and others are referring to are something else entirely. 

[Dakpilot]

Damage is not due to overheating in WEP.

 

Just like Russian planes would not go 100% all the time. Yet they do in game

 

Do you understand what maximum continuous power rating is and the concept of that?

 

Do German engines run all the time at max continuous settings? yes they do 

 

 

Cheers Dakpilot

Edited January 2, 2018 by Dakpilot

[1/JSpan_Wind75]

When you want to have a great car you buy a Lada, not a BMW or Mercedes. The BMWs and Mercedes break their engines and the Lada does not 

[Blutaar]

 

 

Good question. I wonder where we could find the answer... The engines also didn't have any recording device, how would you keep track how many times/minutes you used emergency power? Write the times in a notebook while in combat? Check notebook and calculate if you have enough minutes in the "budget" every time you're in emergency? I'd guess if those minutes were really that important there would be some kind of indicator like the ammo counter to keep track of the remaining boosts and not run out of minutes...

 

Thats exactly what i mean, there must be a way to know how often or how long you could run WEP/Notleistung per Flight or per engine. Otherwise these settings would not make sense and should be disabled if its unsafe. This is a question nobody could give me a satisfying answer to. Maybe the tests could give an estimation for the duration an engine could handle WEP/Notleistung when it is fresh. 

 

Using a stopwatch while dogfighting and throttling back when the time is up while you are almost in firing range sounds pretty unrealistic. Especially if you are in front of the guy who is almost in firing range lol.

[Sgt_Joch]

The time to wear the engine out from WEP is measured in HOURS, not minutes. 

 

well no, that type of comment makes me me think you have no clue about basic engine operation. If you did, you would not be making totally unrealistic comments like suggesting that time limits be removed entirely.

 

Once you start exceeding the maximum safe limits on an engine, you run the risk of failure. At what time, how long it lasts, depends on a lot of factors, but it was never, ever hours.

 

If you look at the history of the DB601/605 engine, you can clearly see the Germans were already pushing the envelope in terms of producing power.

 

Look at the DB605 engine used in the 109G series. The Germans wanted to develop a more powerful engine than the DB601 used in the 109F. They were stuck with 87 octane B4 fuel, so instead bumped up the displacement by a few liters and bumped up the basic CR from 6.9:1 to 7.5:1.

 

Well of course, once you add ATA1.42 to a DB605, you wind up with an effective CR which is higher than in a DB601 and as a result early 109Gs had a host of problems: blown pistons, oil fires, oil lubrication failure. That is why the DB605 was blocked at  ATA1.30 for a long time, since the additional pressure/heat from running at ATA 1.42 could easily cause instant engine failure.

 

 

 

"Take-off and emergency power" may not be used; this stage is blocked in order to prevent over pressure. Die Leistungsstufe 'Start -und Notleistung' darf nicht benutzt werden; um Überdrücken zu verhindern, ist diese Stufe blockiert.

 

http://www.spitfireperformance.com/spit9v109g.html

 

since the DB605 was just a design refinement of the DB601 engine used in the 109F, you can also see that engine was also being pushed close to its max.

 

Note also that the max emergency power of the DB605 without MW50, (which is an whole other animal btw), also stayed around ATA 1.4 all the way to 1945, at a time when the 109 was competing against very powerful Allied fighters and the GAF was desperate for extra HP out of its engines. It is  a bit ludicrous to think the GAF was still setting absurdly low operating limits in 44-45 just  to extend the time between overhauls  .

 

Again, everyone, even the Devs agree the current system is too restrictive, but removing engine limits entirely is totally unrealistic and a silly suggestion.

Edited January 2, 2018 by Sgt_Joch

[LColony_Kong]

well no, that type of comment makes me me think you have no clue about basic engine operation. If you did, you would not be making totally unrealistic comments like suggesting that time limits be removed entirely.

 

Once you start exceeding the maximum safe limits on an engine, you run the risk of failure. At what time, how long it lasts, depends on a lot of factors, but it was never, ever hours.

 

If you look at the history of the DB601/605 engine, you can clearly see the Germans were already pushing the envelope in terms of producing power.

 

Look at the DB605 engine used in the 109G series. The Germans wanted to develop a more powerful engine than the DB601 used in the 109F. They were stuck with 87 octane B4 fuel, so instead bumped up the displacement by a few liters and bumped up the basic CR from 6.9:1 to 7.5:1.

 

Well of course, once you add ATA1.42 to a DB605, you wind up with an effective CR which is higher than in a DB601 and as a result early 109Gs had a host of problems: blown pistons, oil fires, oil lubrication failure. That is why the DB605 was blocked at  ATA1.30 for a long time, since the additional pressure/heat from running at ATA 1.42 could easily cause instant engine failure.

 

 

http://www.spitfireperformance.com/spit9v109g.html

 

since the DB605 was just a design refinement of the DB601 engine used in the 109F, you can also see that engine was also being pushed close to its max.

 

Note also that the max emergency power of the DB605 without MW50, (which is an whole other animal btw), also stayed around ATA 1.4 all the way to 1945, at a time when the 109 was competing against very powerful Allied fighters and the GAF was desperate for extra HP out of its engines. It is  a bit ludicrous to think the GAF was still setting absurdly low operating limits in 44-45 just  to extend the time between overhauls  .

 

Again, everyone, even the Devs agree the current system is too restrictive, but removing engine limits entirely is totally unrealistic and a silly suggestion.

Yeah no....

 

Thing is, we are not exceeding the limits of the engine. Power rating were approved largely on the basis on how long they wanted the engine to last. The available power is not usually even close to being the literal physical limit. The fact that you dont get this after this many pages make me think you dont know how this stuff works. 

[JtD]

 

 

Once you start exceeding the maximum safe limits on an engine, you run the risk of failure. At what time, how long it lasts, depends on a lot of factors, but it was never, ever hours.

There were no "safe" limits on these engines back in the day. They just failed, all the time, without exceeding manual figures that were supposedly "safe".

 

The approval run procedure for German aero engines at the time included a long time run (over the course of 100 hours, iIrc), at a regime of 30min combat, 5min emergency, 25min maximum continuous, and repeat. So any approved engine would have completed a type test that included 8h of emergency operation without major failures, indicating that wear was truly no issue to be measured in minutes. Similar type tests were used in other countries.

 

Thermal issues are a different thing, but they depend as much on the circumstances as they do on the design / nominal performance.

[Venturi]

 

 

There are also hundreds of reports of P-38 Allison engine blowing up used in ETO

 

 

 

A disingenuous statement, if factually true.

 

The reason the engines blew up, is because of inproper use of the engine RPM / MP specifications.

 

And, I quote: 

 

“After flying the P-38 for a little over one hundred hours on combat missions it is my belief that the airplane, as it stands now, is too complicated for the ‘average’ pilot,” wrote Rau. “I want to put strong emphasis on the word ‘average,’ taking full consideration just how little combat training our pilots have before going on operational status.”

 

Rau wrote that he was being asked to put kids fresh from flight school into P-38 cockpits and it wasn’t working. He asked his boss to imagine “a pilot fresh out of flying school with about a total of twenty-five hours in a P-38, starting out on a combat mission.” Rau’s young pilot was on “auto lean and running on external tanks. His gun heater is off to relieve the load on his generator, which frequently gives out (under sustained heavy load). His sight is off to save burning out the bulb. His combat switch may or may not be on.” So, flying along in this condition, wrote Rau, the kid suddenly gets bounced by German fighters. Now he wonders what to do next.

“He must turn, he must increase power and get rid of those external tanks and get on his main [fuel tank],” Rau wrote. “So, he reaches down and turns two stiff, difficult gas switches (valves) to main, turns on his drop tank switches, presses his release button, puts the mixture to auto rich (two separate and clumsy operations), increases his RPM, increases his manifold pressure, turns on his gun heater switch (which he must feel for and cannot possibly see), turns on his combat switch and he is ready to fight.” To future generations this would be called multi-tasking, and it was not what you wanted to be doing when Luftwaffe fighters were pouring down on you.

“At this point, he has probably been shot down,” Rau noted, “or he has done one of several things wrong. Most common error is to push the throttles wide open before increasing RPM. This causes detonation and subsequent engine failure. Or, he forgets to switch back to auto rich, and gets excessive cylinder head temperature with subsequent engine failure.”

[Venturi]

There were no "safe" limits on these engines back in the day. They just failed, all the time, without exceeding manual figures that were supposedly "safe".

 

Very much agree - there was increasing likelihood of problems at increased power levels but no guaranteed failure. Up to the point at which detonation started.... which point primarily depended on what fuel was being used. The Allison V-1710-39 for instance, had a design strength of 1500 hp at 61" Hg manifold pressure and 3000rpm. The detonation point of the 100/130 (lean/rich ratings) fuel used was around 65" Hg (rich mix). The engine was rated at 1470hp / 56" Hg 3000rpm for 5 min... and there are manifold reports of pilots using it beyond this point without outright failure... but if that pilot overboosted the engine to the detonation point, some 9" Hg above the rated power, you would have a dead engine very quickly indeed. The issue is that it was difficult to do with a single stage, single speed supercharger except at very low altitudes and high speeds (ram effect). So most pilots "firewalling it" probably didn't see the detonation point...

 

Edited January 2, 2018 by Venturi

[Corsair]

I inadvertently launched a double topic here (https://forum.il2sturmovik.com/topic/33343-bf-109-engine-management-question/). As far as I tested the engine blow up at 1.42 ata is indeed """random""" but with very narrow distribution (10-15 second discrepancy in blow up timer after a dozen of tests).

 

What do you think of the blow up probability mentioned on posts #12 and 13? https://forum.il2sturmovik.com/topic/33343-bf-109-engine-management-question/?p=554651

[Venturi]

Yes, there is randomness in the current model. But it is far too little, and far too invariable.

 

You don't need "just a little" randomness. You need a lot of randomness... enough to realistically portray the risk of pushing the engines, as was historical.

 

Again, have a "nominal" power level - at which safe operation is guaranteed. Use the published manual limits for this. Add in a interval random check for cumulative damage to the engine when beyond this power level and "safe" time. Base the length of the interval check on the TBO times for the specific engine model... (rough estimate of engine durability under combat conditions).

 

If you then add in the hard-check "detonation" at the limits of the fuel's capacity (over 65" Hg for 100/130 fuel, for instance) - and add in MP / RPM mismatch and lean and rich mix consequences, you have a complete overhaul which is fairly straightforward to accomplish and also realistic.

 

But there are multiple ways to do the same thing, this is only my suggestion. I have written at length about this before, you can use search.

Edited January 2, 2018 by Venturi

[Corsair]

I have just read it indeed, and most definitely agree with such a proposed model.

[LColony_Kong]

I cant say I agree with the idea of random engine detonation. Nobody wants to be killed by the RNG machine, and doing this in here would open up the door logically to a whole different can of worms. At that point we might as well add random engine failure on takeoff. 

 

The other issue with that sort of thing is that it again hearkens back to the idea of trying to simulate things that cant really be simulated. I cant scold my crew chief for not doing the maintenance right. I cant call up DB to complain about manufacturing errors etc. 

 

Nobody wants to come home form work, hope on WoL, and have your engine randomly fail when trying to spiral climb a Yak. 

[Venturi]

If you push your engine beyond the safe limits, then randomness should kick in... then your confidence in your plane is dependent on the chance that your favorite (russian, american, german, british) engine will withstand your abuse...

But it is important that the randomness is significant and based on real TBOs... this makes it based on fact to some extent. 

 

It is also important that a hard check of maximum MP (from detonation) is implemented... with immediate consequences...

Last thing... 

 

simmers will always be simmers, gamers will always be gamers...

[LColony_Kong]

If you push your engine beyond the safe limits, then randomness should kick in... then your confidence in your plane is dependent on the chance that your favorite (russian, american, german, british) engine will withstand your abuse...

But it is important that the randomness is significant and based on real TBOs... this makes it based on fact to some extent. 

 

It is also important that a hard check of maximum MP (from detonation) is implemented... with immediate consequences...

Last thing... 

 

simmers will always be simmers, gamers will always be gamers...

That really depends on whether you are exceeded limits. 

 

Broadly speaking, none of the WEP limits on most ww2 planes are over the limit. Pushing the engine harder is not the same as exceeding its limits. The only sort of thing that should be considered exceeding the limits is something like running 1.8ata from a DB605 without MW50 being on. As has been pointed out, even nominal engine powers run risk of failure. There is no such thing as a perfectly safe setting with a zero percent chance of detonation. Random variation is a bad idea that takes away player agency. 

Edited January 2, 2018 by Fumes

[Venturi]

Life is random my friend.... limits are there to show where the inflection point is...

[Dakpilot]

Anyone care to comment on Interview with Luftwaffe pilot Franz Stigler

 

 

 

"Did you ever have the GM-1 boost or MW-50 in any of your planes? 

Oh yeah, we used it quite often…in combat you know.

How long did it last? 

Uhh…you were not allowed to have it at more than 5 min., you know…if you used it 10 minutes, then motor has to come out.

It makes the engine worse?

It wrecks the motor.

And this was for the higher altitude?

Higher…yes…

And at what speed could you get up to?

Oh boy…I don’t remember…450 or 500 km…

Like you said, you could only use it for 5 min. otherwise you would burn out the engine. How many 5 min. intervals could you use? Did you have to shut it down for a period of time to let the engine cool?

That’s okay…that uh…it didn’t matter. You…but you never used it for five minutes… a minute, minute and a half and that’s it."

 

Cheers, Dakpilot

[LColony_Kong]

Life is random my friend.... limits are there to show where the inflection point is...

But there is no inflection point. We are not over a limit any more than I would be exceeding the limits to drive my car at max revs the entire time. It would certainly last alot less long, but its almost certainly not going to just choke on me then and there. 

 

Not to mention that modeling it like would be utterly inconsistent with the rest of the game. I cant wait for peoples brakes to fall off because they land to fast. Or guns randomly jam. Or hey, perhaps we should have russian fighters be forced to fly with the canopy open because fumes form the engine had leaked into the cockpit, along with 140 degree heat because we ran the coolant lines under them.....

 

The only thing you can do in a game is model the functioning gear. Anything else is an exercise in absurdity and inconsistency that will produce something that will not be fun to even the most hard core simmer. 

Edited January 2, 2018 by Fumes

[LColony_Kong]

Anyone care to comment on Interview with Luftwaffe pilot Franz Stigler

 

 

 

"Did you ever have the GM-1 boost or MW-50 in any of your planes? 

 

Oh yeah, we used it quite often…in combat you know.

 

How long did it last? 

 

Uhh…you were not allowed to have it at more than 5 min., you know…if you used it 10 minutes, then motor has to come out.

 

It makes the engine worse?

 

It wrecks the motor.

 

And this was for the higher altitude?

 

Higher…yes…

 

And at what speed could you get up to?

 

Oh boy…I don’t remember…450 or 500 km…

 

Like you said, you could only use it for 5 min. otherwise you would burn out the engine. How many 5 min. intervals could you use? Did you have to shut it down for a period of time to let the engine cool?

 

That’s okay…that uh…it didn’t matter. You…but you never used it for five minutes… a minute, minute and a half and that’s it."

 

Cheers, Dakpilot

-I already posted several examples that say quite the opposite, as well as hard tests that override pilot anecdote. 

 

-Yes the motor had to come out. I already said this was the case for P-51s for similar reasons. This is a maintenance precaution, not because the motor was dead. 

 

-This entire conversation is generic. "It wrecks the motor" could mean just about anything, including simply that overuse the the engine would wear it out. It doesn't mean the engine imploded, which is self-evident since he somehow got back to base to have the engine removed. 

 

-Who cares how long he wanted to use the engine for. Again pilots being cautious is not evidence of actual failure of the type we have in game right now. 

 

-Also, the man couldn't even remember how fast he could go for certain. Clearly this is concrete evidence from a technical expert!

Edited January 2, 2018 by Fumes

[ZachariasX]

But there is no inflection point. We are not over a limit any more than I would be exceeding the limits to drive my car at max revs the entire time. It would certainly last alot less long, but its almost certainly not going to just choke on me then and there. 

 

Not to mention that modeling it like would be utterly inconsistent with the rest of the game. I cant wait for peoples brakes to fall off because they land to fast. Or guns randomly jam. Or hey, perhaps we should have russian fighters be forced to fly with the canopy open because fumes form the engine had leaked into the cockpit, along with 140 degree heat because we ran the coolant lines under them.....

 

The only thing you can do in a game is model the functioning gear. Anything else is an exercise in absurdity and inconsistency that will produce something that will not be fun to even the most hard core simmer.

 

A DB605 is hardly a good comparison to you cars engine regarding rated power and endurance. Different engines push limits differently. And the DB605 certainly pushed the limits as fuel and lubrication was not matching on average what the allies could use.

 

Although I see the point Venturi is making, I doubt that this „randomness“ is an accepable situation. Some simmers are very competitive. Having this random timer as he describes, this would decide duels. This is a no-go.

 

Some engines fail faster than others, but I think having heat production such that this would make failures less sudden and more manageable via radiators. Opening them too far more than cancels out the performance gain. It would not be 100% realistic in all cases, but on average I guess it would make things less frustrating.

[ZachariasX]

- ....snipp....

-Also, the man couldn't even remember how fast he could go for certain. Clearly this is concrete evidence from a technical expert!

I hope you can remember such technicalities at the same age he was, when he gave the interview. Otherwise there might be people thinking you are unqualified.

[JtD]

Anyone care to comment on Interview with Luftwaffe pilot Franz Stigler

 

The least realistic aspect currently in this game is the player, and I expect it will continue to be so. Players will do what the game permits them to do, pilots will do what gives them the best chance for survival. So it's not surprising that the use of engine power settings in real life was considerably different to the use in game.

Edited January 2, 2018 by JtD

[Dakpilot]

Not remembering specific top speeds of one aircraft of many flown in a career is not unusual 

 

(I can think of 4 aircraft I don't remember VNE on let alone what speed I could get out of them)

 

but he is very specific 

 

"but you never used it for five minutes… a minute, minute and a half and that’s it"

 

I don't feel you can disregard his technical expertise from that, Franz Stigler is a fairly well known and experienced pilot/Luftwaffe Ace

 

Cheers, Dakpilot

[LColony_Kong]

I hope you can remember such technicalities at the same age he was, when he gave the interview. Otherwise there might be people thinking you are unqualifYou 

You are missing the point. 

[Inkophile]

 

 

Yes, there is randomness in the current model. But it is far too little, and far too invariable. You don't need "just a little" randomness. You need a lot of randomness... enough to realistically portray the risk of pushing the engines, as was historical.

 

I really, REALLY wouldn't want this in the game, because it is a game. Players need to understand why things happen, and if things happen at random there really isn't anything the player can do about it. When factors are entirely outside of the player's control that's where people will start getting frustrated. Really frustrated.

 

If we add random engine failure during emergency operation we need to add engine failure during all operation. Then maybe non-functioning brakes just because they've freezed up. Random failure of the landing gear locks so you can't even deploy the undercarriage. Random gun jams where your cannon stops working after the third shot and you can't re-cock it in the air. Ammunition failure with bad primers or bad fuzes. Let's add random oxygen failure too, and maybe random wing loss because the airframe was a bit old/worn so the wing could only take 11 Gs instead of the proofed 12 G (which means that it can take maybe 14 G before failing, since 12 is the guaranteed strength). We could add random failure to the propeller pitch governor as well, or maybe that the supercharger clutch fails halfway through the flight even though it by no means should have been clutching/declutching so often that it is because of overheating. Oh, and I forgot about the electrical system with fuses, vacuum tubes and light bulbs burning out. Really fun with a random fuse failure in the middle of the fight which makes your guns inoperable (German planes since they used electric gun control)!

 

 

Yes, I am pushing this to the extreme, but my point is: where does the randomness end. If we add randomness and take away control from the player in one area, then shouldn't we take away player control in more areas?

 

 

And in addition to all this, how are they supposed to add "random" engine failure that makes sense? This entire thread can agree that engine failure happens under certain circumstances, be it exceeding critical detonation-levels or simply wearing stuff out, but exactly what are those limits? How can the devs add realistic random engine failure if there is (and I guarantee that this is the case for most of the engines in the game) insufficient data to describe in detail the circumstances of engine failure for any specific engine model? There is a shitload of anecdotal evidence and testimonies, but they aren't really worth anything. Only hard data is.

 

If such data is lacking, how should the devs go about it? Complex, computer-generated engine simulations to calculate failure parameters to put into the game, taking away from other dev-time and/or development costs? Is it worth it?

[Venturi]

It is very simple.

 

There are NO random failures unless you push the engines to extreme levels, only past the guaranteed safe time as prescribed in the manuals.

 

You base the interval of random damage check on historical TBO times of the specific engine models.

 

It is very simple, and much more realistic than the status quo. It would also make sure players don’t abuse the (random - but definite) leeway they are receiving from the prescribed operation times at high power levels.

 

Just like the real pilots.

[Sgt_Joch]

so, from the way the discussion is going, I guess we all agree , since it is an indisputable fact, that engines do have limits...or are some still arguing that the earth is flat? 

 

Everyone agrees the current system is too restrictive, but the issue as usual is a lack of data. Every country set operating limits on their AC, but it is hard to determine how much farther you could push the engines without blowing them up.

 

This article,on setting the WEP limits on the P38 is instructive. Note the bolded parts:

 

 

The maximum speed and climb performance of the various P-38 models is, however, something of a mystery. Although rated takeoff power from the XP-38 through the P-38H increased from 1150 bhp to 1425 bhp the Tactical Planning Charts issued by Wright Field show all variants with a similar speed. Closer examination of the charts will reveal that all P-38 powerplants, through the H model, are limited to 1150-1240 bhp, due to "inadequate cooling."

 

To be more specific, the foremost problem was the temperature of the compressed air from the turbosupercharger entering the carburetor. High carburetor air temperature (CAT for short) can cause all kinds of engine problems including detonation, which can lead to catastrophic engine failure. Allison recommended a CAT of no more than 45 degrees C.

 

As it turned out high CAT was one of the major problems limiting P-38 performance through the P-38H. The root cause was, of course, the limited cooling ability of the wing leading edge intercoolers found in all early P-38s. They were a very clever design, inducing almost no aerodynamic drag, but they were designed for the 1000 hp Allisons of the late 1930s. By 1943 Military power was up to 1425 bhp and War Emergency Power was 1600 bhp. The increased power required higher induction pressure, which through compression by the superchargers heated the air by several hundred degrees. There is no way that the simple intercoolers could keep CAT below 45 degrees C. when operating at high power at altitude.

 

On the other hand, Ben Kelsey (now a Colonel) and Colonel Cass Hough, of the Eighth Air Force Technical Section, had different ideas about CAT. They were of the opinion (as were many of the fighter pilots) that American fighter engines were still being used at conservative, peacetime power settings, which were inadequate for combat. With this in mind they set out to determine just how much abuse a P-38 engine could take, and what they found surprised everyone.

 

The first P-38s to arrive in England were rated at 42" up to about 20,000 feet, 40" at 25,000 feet, with further reductions above that. Colonel Hough decided the best way to find out how much power was actually available without blowing up the engines was to remove the throttle stops and find out for himself. This made full throttle available at any altitude. Operating like this, Hough spent two weeks "abusing the engines", searching for their maximum limit. "We found that below 25,000 feet we could pull up to 60" of manifold pressure without material harm, and we could run as high as 40" at 40,000 feet (60" would yield around 1600 + bhp/ engine). He did warn that this kind of abuse should be of short duration. Col. Kelsey was busy doing the same thing at the Lockheed plant in California.

 

In a February 1943, P-38 Progress Report, Kelsey described how he had been "beating engines unmercifully". The F-10 engines in the P-38G had been run at 51" (1440 bhp) or more for periods of 7 and 8 minutes. "A series of climbs have been made at this power from takeoff to 22,000 feet…" "From our best previous estimates of limiting carburetor air temperature to 45 degrees, 51" could not be pulled above 15,000 feet." "Actually, 70 degrees C. has been run satisfactorily". "We have not yet established actual limits".

 

In March Kelsey reports: "I finally succeeded in reaching limiting carburetor air temperature at altitude. I got excessive roughness, cutting out, and backfires at 190 and 200 degrees F [88 and 93 degrees C]. at about 25,000 feet"… one intercooler was actually blown up". "We very evidently have much larger tolerances in temperature, back pressure and carburetor air pressure than we anticipate".

 

Kelsey and Hough were looking for a compromise…they wanted the most power available without engine damage. Kelsey recommended a combat rating of 47" at 3000 rpm (1325 bhp) to 20,000 feet. He also recommended a 5-minute limit at 50 degrees CAT. Eighth Fighter Command was more conservative; they eventually established a War Emergency Power rating of 45" up to 25,000 feet. Wright Field, with more responsibility, was even more conservative and recommended a Military Power of only 41” (1150 bhp). War Emergency Power was not recommended. This was essentially the same power available to the XP-38 in 1939!

 

In the end, the various U.S. Air Forces set their limits somewhere between Kelsey and Wright Field. Actually, it was the fighter pilots and their crew chiefs that often had the last word on how the powerplant controls were rigged, and it was not uncommon practice to remove the throttle stops on operational P-38s. This provided full throttle (60-70" of manifold pressure) at lower altitudes, but it greatly increased the chance of blowing the engine. Many pilots thought that since they were the ones risking their lives on the cutting edge, it was only fair that they should decide how to use the power. The author has a friend who flew the P-38H, J and L models with the 55th Fighter Group, Eighth Air Force. He told me that he had the throttle stops taken off all three aircraft and, when necessary, used full throttle in combat. He had no problems with the H model overheating.

 

http://www.wwiiaircraftperformance.org/p-38/p-38-wayne.html

 

This article is interesting for a few points:

 

1. everyone involved, including the actual pilots, knew that if you pushed boost/WEP high enough and long enough, the engine would implode. 

 

2. it shows that the only criteria for setting engine limits, was getting the most performance out of it without actually destroying the engine. Note how "getting the most hours between overhauls " is not even a consideration. 

 

3. Note also that the operating limits and what the actual pilots thought were the real limits are not that far apart, i.e. Ben Kelsey thought 51" for 7-8 minutes was close to the max. There are two recommendations to set it at 45-47", so not a lot of headway for improved performance. Note also that is was generally known that US forces were more conservative in their settings than the Germans, so there is a good chance the limits on the 109 engines are already closer to the edge.

 

so we are back to the same issue, following the limits in the flight manual are too restrictive, but no one knows are far the limits should be. Ideally, you would have a system where damage from WEP would be random, with chances increasing or decreasing, based on duration and engine temperature.

Edited January 3, 2018 by Sgt_Joch

[Venturi]

I guess the only real question remaining, is, does WEP mean 45” HG on a V-1710-39... or is it 56”? ...

[LukeFF]

 

 

Or guns randomly jam.

 

Rise of Flight has weapon misfires, and it's never been the end of the world. 

[CUJO_1970]

Not remembering specific top speeds of one aircraft of many flown in a career is not unusual 

 

(I can think of 4 aircraft I don't remember VNE on let alone what speed I could get out of them)

 

but he is very specific 

 

"but you never used it for five minutes… a minute, minute and a half and that’s it"

 

I don't feel you can disregard his technical expertise from that, Franz Stigler is a fairly well known and experienced pilot/Luftwaffe Ace

 

Cheers, Dakpilot

 

 

I have the impression he never used it for five minutes because he never needed to use it for five minutes.

 

It seems you could run it at intervals of five minutes, but never exceed five minutes continuous at a time.

 

Simply my impression though, which could be wrong of course.

[CUJO_1970]

Pilots and crew chiefs ran the engines over factories specs many times, you can find many accounts and even when the get in trouble for doing it.

 

Norbert Hannig talks about over boosting the FW190-A6 and using it in combat - some other crews were overboosting the BMW 801 and the got in trouble for it by either RLM or BMW.

 

The FW-190 we have cleared for in bomber version was later tested in fall 1943 and then officially cleared for 1.65ata for fighter versions of A5 and A6.

[LColony_Kong]

Rise of Flight has weapon misfires, and it's never been the end of the world. 

And we have problematic net code, it the sky hasnt fallen either. 

 

Saying you can put up with it isnt an argument. 

[Corsair]

And we have problematic net code, it the sky hasnt fallen either. 

 

Saying you can put up with it isnt an argument. 

One is a feature, the other is a bug(s).. I don't mind simulating malfunctions (at a certain point) and do not get the player frustration argument.

Edited January 3, 2018 by EC5/25_Corsair

[LColony_Kong]

so, from the way the discussion is going, I guess we all agree , since it is an indisputable fact, that engines do have limits...or are some still arguing that the earth is flat? 

 

Everyone agrees the current system is too restrictive, but the issue as usual is a lack of data. Every country set operating limits on their AC, but it is hard to determine how much farther you could push the engines without blowing them up.

 

This article,on setting the WEP limits on the P38 is instructive. Note the bolded parts:

 

 

http://www.wwiiaircraftperformance.org/p-38/p-38-wayne.html

 

This article is interesting for a few points:

 

1. everyone involved, including the actual pilots, knew that if you pushed boost/WEP high enough and long enough, the engine would implode. 

 

2. it shows that the only criteria for setting engine limits, was getting the most performance out of it without actually destroying the engine. Note how "getting the most hours between overhauls " is not even a consideration. 

 

3. Note also that the operating limits and what the actual pilots thought were the real limits are not that far apart, i.e. Ben Kelsey thought 51" for 7-8 minutes was close to the max. There are two recommendations to set it at 45-47", so not a lot of headway for improved performance. Note also that is was generally known that US forces were more conservative in their settings than the Germans, so there is a good chance the limits on the 109 engines are already closer to the edge.

 

so we are back to the same issue, following the limits in the flight manual are too restrictive, but no one knows are far the limits should be. Ideally, you would have a system where damage from WEP would be random, with chances increasing or decreasing, based on duration and engine temperature.

Again again again. 

 

How many time do I have to say this?

 

You keep spewing on about the hard limits, but we are not talking about those. Of course engines eventually hit power they cant handle, and likely fail immediately. WEP is not that. WEP is a setting that is within the hard limits but stresses the parts harder. It does not cause the engine to fail in 5min. You are confusing abusive behavior with catastrophic behavior. And you keep hammering on it like the definitions are going to change all of a sudden.

 

What this article shows, in actual fact, is that the WEP ratings were absolutely at levels thought possible for use. 60-70 MAP  would not have been allowed if it caused imminent engine seizure: This would have been pointless to allow if it had. Did it make it more likely that some part might fail? Sure. But then again, your air frame has a higher chance of failure at the max G-limit of the air frame. Now and again, you might have a plane that fails when it pulls its rated limit. Crap happens. But that does not mean we should look at proscribed limits as certain failure points. 

 

But lets also highlight some bits you glossed over:

 

In the end, the various U.S. Air Forces set their limits somewhere between Kelsey and Wright Field. Actually, it was the fighter pilots and their crew chiefs that often had the last word on how the powerplant controls were rigged, and it was not uncommon practice to remove the throttle stops on operational P-38s. This provided full throttle (60-70" of manifold pressure) at lower altitudes, but it greatly increased the chance of blowing the engine. Many pilots thought that since they were the ones risking their lives on the cutting edge, it was only fair that they should decide how to use the power. The author has a friend who flew the P-38H, J and L models with the 55th Fighter Group, Eighth Air Force. He told me that he had the throttle stops taken off all three aircraft and, when necessary, used full throttle in combat. He had no problems with the H model overheating.

 

 "A series of climbs have been made at this power from takeoff to 22,000 feet…" "From our best previous estimates of limiting carburetor air temperature to 45 degrees, 51" could not be pulled above 15,000 feet." "Actually, 70 degrees C. has been run satisfactorily". "We have not yet established actual limits".

 

In March Kelsey reports: "I finally succeeded in reaching limiting carburetor air temperature at altitude. I got excessive roughness, cutting out, and backfires at 190 and 200 degrees F [88 and 93 degrees C]. at about 25,000 feet"… one intercooler was actually blown up". "We very evidently have much larger tolerances in temperature, back pressure and carburetor air pressure than we anticipate".

 

Kelsey and Hough were looking for a compromise…they wanted the most power available without engine damage. Kelsey recommended a combat rating of 47" at 3000 rpm (1325 bhp) to 20,000 feet. He also recommended a 5-minute limit at 50 degrees CAT. Eighth Fighter Command was more conservative; they eventually established a War Emergency Power rating of 45" up to 25,000 feet. Wright Field, with more responsibility, was even more conservative and recommended a Military Power of only 41” (1150 bhp). War Emergency Power was not recommended. This was essentially the same power available to the XP-38 in 1939! (clearly power settings by actual armies were far below possible ratings. )

 

And form before: "Regarding the various comments about throttling back or up a P-38 engine to increase maneuverability I can only repeat that this was not practiced as far as I know. When I was overseas in 44 and 45, flying the J winter thru summer, the policy was to drop tanks and push up MP to 45 inches when German fighters were spotted in a position where an engagement was likely. When you actually went for them, throttle up to WEP, 60 inches or so, rpm all the way up too, up past 3000 rpm. And there it would stay until the engagement was over and you remembered to throttle back. You could easily be at WEP for 20 minutes or more."

One is a feature, the other is a bug(s).. I don't mind simulating malfunctions (at a certain point) and do not get the player frustration argument.

Because it takes away player agency, and does so on top of the fact that all the extraneous factors the would affect it are not simulated. Its folly to start adding silly abstractions that ruin game play and ruin that actual bit of simulation that was being done more or less correctly. Perhaps the next time you hop in game and press "E" the engine will fail to start because it is too cold! And your not allowed to get a new airplane, you have to wait on the tarmac for the mechanic to address the problem. And then when you get back you can chew him out. Also when you use WEP next time, the game should have a simulated set of paper work for you to fill out! Also your cockpit glass should freeze over. And sometimes you should spawn with a plane that hasnt had the maintenance done by its lazy crew, and your engine stops just as you are about to attack. Or maybe someone at the factory sabotaged it. Perhaps guages should read erroneously from time to time. 

Edited January 3, 2018 by Fumes

[Corsair]

 

 

Because it takes away player agency, and does so on top of the fact that all the extraneous factors the would affect it are not simulated. Its folly to start adding silly abstractions that ruin game play and ruin that actual bit of simulation that was being done more or less correctly.

 

Then make it a realism setting, and everyone is happy.. of course I'm not advocating 'simulation' of factors that you quote.. we are not in a mechanics simulation. But I believe a reasonable simulation of failures, for instance when badly managing war emergency engine power settings, deserves much better than a mere timer that is not even random and with ultimately always the same result... 

[LColony_Kong]

 But I believe a reasonable simulation of failures, for instance when badly managing war emergency engine power settings, deserves much better than a mere timer that is not even random and with ultimately always the same result... 

 

I have alot of issues with this, but I am only going to hit on one. 

 

RNG is bad for games. Its dumb to have things fail at random, especially when the change of it doing so IRL is extremely low. It would be completely asinine to get into a dogfight and suddenly have your engine fail or wing fall off. This would go far beyond engines, which is the point I was making earlier. 

 

It isnt as simple as making everyone happy by making it a editor setting. You run the risk of ruining multiplayer if every server runs it as you put above, and it stripes the game of any sort of competitive aspect. 

Edited January 3, 2018 by Fumes

[JtD]

Il-2:1946 has random engine failures and they work great there, imho. Reduces engine abuse by the players, without annoying anyone. At least to my knowledge. Even if it can happen at any power setting, you only really need to worry when you fly the engine flat out. Sooner or later you will blow a piston or oil will start leaking or something like that. It doesn't keep you from using emergency settings in an emergency, but keeps you from flying flat out all day.

[LColony_Kong]

Il-2:1946 has random engine failures and they work great there, imho. Reduces engine abuse by the players, without annoying anyone. At least to my knowledge. Even if it can happen at any power setting, you only really need to worry when you fly the engine flat out. Sooner or later you will blow a piston or oil will start leaking or something like that. It doesn't keep you from using emergency settings in an emergency, but keeps you from flying flat out all day.

I dont really like this idea for the above reasons

 

BUT

 

IF there were some RNG failure it should be after a tactically useful amount of max power use....say 10-20min. That way people have a consistently usable amount of max power they can use that "solves" all of the issues that have been discussed here:

 

-If I have 10-20min of full power on every plane, then you wont really have issues with slower fighters running people down due to arbitrary time limits etc

 

-If you have 10-20min then you ALSO dont get people running around the entire duration of their flight at max power, since it would use up that power when they need it for combat. 

[Barnacles]

The Devs say they have the aspiration to simulate detonation in engines eventually in BoS. I reckon that when they implemet this they may well revisit the current engine damage thing. This should make most people happy as long as A. it isn't simulated by a streetfighter style health bar in the HUD that gets whittled down when you rag the engine. B. It means that online people don't just fly around at full power all the time.