7 1/2 Hour War Emergency Test of Pratt&Whitney R-2800 26 April 1944

[=475FG=_DAWGER]

A realistic engine model does not require huge amounts of computer power.

 

It is a fairly simple relationship of temperature and pressure. 

 

At some combination of temperature and pressure, detonation occurs which results in power loss (should be obvious why) and engine damage begins to occur. This damage occurs first to bearings and is more long term in nature and no need to simulate. So mild detonation for a while would have no effect but there would be a power loss. As the detonation progress occurring earlier in the piston stroke and more violent as temperature and pressure rise, damage to the cylinder walls begins to occur.

 

The longer the engine is operated in detonation, the more damage. This damage can create hot spots in the cylinder which can then cause pre-ignition. Pre-ignition due to hot spots can then occur at power settings lower than those that result in detonation.

 

So lets say a hypothetical engine has operational limitations of 52 inches manifold pressure (" MP) at 2700 revolutions per minute (RPM) for 5 minutes at 500 degrees cylinder head temperature (°CHT).

 

The same engine may be operated 42 " MP / 2550 RPM 450 °CHT continuously, the key being to get the MP below 43 ".

 

The assumption by the engineers is that when the engine is operated at 500 ° CHT for 5 minutes and then power is reduced to the maximum continuous setting, cooling will occur at a rate that will prevent engine damage. Once the engine is back below 451° CHT it may again be operated at its emergency maximum for 5 minutes without damage occurring. This cycle can be repeated many times on a new engine with no significant damage.

 

A realistic engine model would simulate detonation outside of the above limits by applying power loss when the limits are exceeded and that power loss would become progressively worse as the time and temperature spent above the detonation limit increased. At some point, permanent engine damage can be simulated by a power loss at power settings that are not above the detonation threshold. Continue to push the engine and catastrophic failure would become a real possibility.

 

These aren't complex formulas. CHT rise in this example should occur at a rate that generates 500° CHT about 5 minutes after Emergency power is applied for average atmospheric conditions (all engine types) and airspeed (air cooled engine). Reduce the power or the temperature continues to climb and the detonation effects begin to occur. Set hard time above 500° and/or temperature limits for the initial power loss and the progression to ever increasing effects.

 

1 minute above 500° or CHT = 510° the first power loss occurs.

2 minutes above 500° or CHT=520° permanent damage occurs and power loss extends to all power settings above normal cruise

3 minutes above 500° or CHT=530° power loss extends to all power settings and the engine begins to combust the lubricating oil. Engine failure will occur when oil temperature increases and the oil loses its ability to protect the engine from itself.

 

Engine limits must be respected as written but the effects are not random. In my real world experience, this would be an adequate simulation of the way it actually works.

 

 

 

 

 

[Matt]

11 minutes ago, 77.CountZero said:

What combat or emergancy/wep limits we could expect o P-51, P-38, D9 and 262 ? i check manual for tempest v and it looks like same limits as for spit 9 should be for him, but didnt bather to look for other 4 airplanes we stil have to get in game.

I'm not aware of any times limits for the Fw 190 D-9 or Me 262. Some Jumo manual states 30 minutes for combat power, but i'm not sure if that would apply to the Jumo in the Fw 190 D-9 we're getting.

 

P-51 should have 5 minutes WEP and 15 minutes combat power.

 

Couldn't find anything for the P-38, atleast the manuals which i could find do not specify time limits. However, i did not spend a lot of time on that.

 

So based on what i could find so far and if the devs go by operating manuals (which the devs are not doing, even though some people here assume that and seem to enjoy it) :

 

Fw 190 D-9: WEP until MW50 runs out, possibly 30 minutes combat power. 

Me 262: Full power until fuel runs out.

P-51: 5 minutes/15 minutes (neither recoverable, if we go by operating manuals).

P-38: WEP until fuel runs out.

 

Again, this is all what i could find for now, so it's probably not correct. And i'm assuming none of this will actually happen (except perhaps for the Me 262) like this. 

Edited December 13, 2018 by Matt

[CountZero]

ok thanks

[[CPT]Pike*HarryM]

this chart indicates Military power is 15 minutes. 

[Rattlesnake]

3 hours ago, Sgt_Joch said:

 

This issue has been raised and dealt with many time before and no, it is not as simple as you make it out.

 

1. yes, 1050 mm of mercury in the Klimov-105PF works out to 1.37 ATA; but

 

2.the 109F runs on 87 octane B4 fuel while the Yak-1 runs on 95 octane Russian Avgas which has a similar octane level to german c3 fuel. As you know, as a general rule, the higher the octane level, the higher the boost level you can sustain;

 

3. the way engine limits work in game, you get much higher limits at an intermediate setting. For example, in tests I ran some times ago you could run a FW190 A3 at 1.37 ATA (with 96 octane C3 fuel) for 15 minutes or more with no issue. So German engines running with similar ATA/boost level and octane level as the Yak will also last a long time in the current system; and

 

4. it is not true that the Yak-1 engine has no limits, there is a thermal limit. The Yak-1 engine runs hot at 100% throttle/RPM and can easily overheat. If the overheating is not addressed, the engine will fail very quickly.

The problem with the "It's the higher octane!" explanation is that if 1.42 ATA was really pushing the detonation threshold with the fuel the Germans used then it could easily cause problems immediately,  it wouldn't wait around exactly one minute every time before problems ensued. Certainly other nation's WEP time limits on similar engines weren't because detonation would always start soon after exceeding, they were based on encouraging pilots to not needlessly wear out the engines. If octane is the explanation we were rolling with, well I would like to see proof that 1.42 ATA was riding the detonation threshold and that this was indeed the reason for the limitation, as opposed to wear and life concerns.

That still leaves us with the "combat power" problem. Obviously a setting which can be run for 30 minutes at a time is way below the immediate detonation threshold. So I say again, what is the logic behind a hard limit on the DB but not the Klimov when the former is running at lower boost, RPMs, and output?

Pilots of other airplanes would LOVE to be limited by temperature considerations that could be managed and monitored on gauges, instead of basically arbitrary timers.

It still looks like the major difference between the DB and the Klimov limitations is only that the manual writers for the former were trying to encourage pilots towards practices that would extend engine life.

1 hour ago, =475FG=DAWGER said:

A realistic engine model does not require huge amounts of computer power.

 

It is a fairly simple relationship of temperature and pressure. 

 

At some combination of temperature and pressure, detonation occurs which results in power loss (should be obvious why) and engine damage begins to occur. This damage occurs first to bearings and is more long term in nature and no need to simulate. So mild detonation for a while would have no effect but there would be a power loss. As the detonation progress occurring earlier in the piston stroke and more violent as temperature and pressure rise, damage to the cylinder walls begins to occur.

 

The longer the engine is operated in detonation, the more damage. This damage can create hot spots in the cylinder which can then cause pre-ignition. Pre-ignition due to hot spots can then occur at power settings lower than those that result in detonation.

 

So lets say a hypothetical engine has operational limitations of 52 inches manifold pressure (" MP) at 2700 revolutions per minute (RPM) for 5 minutes at 500 degrees cylinder head temperature (°CHT).

 

The same engine may be operated 42 " MP / 2550 RPM 450 °CHT continuously, the key being to get the MP below 43 ".

 

The assumption by the engineers is that when the engine is operated at 500 ° CHT for 5 minutes and then power is reduced to the maximum continuous setting, cooling will occur at a rate that will prevent engine damage. Once the engine is back below 451° CHT it may again be operated at its emergency maximum for 5 minutes without damage occurring. This cycle can be repeated many times on a new engine with no significant damage.

 

A realistic engine model would simulate detonation outside of the above limits by applying power loss when the limits are exceeded and that power loss would become progressively worse as the time and temperature spent above the detonation limit increased. At some point, permanent engine damage can be simulated by a power loss at power settings that are not above the detonation threshold. Continue to push the engine and catastrophic failure would become a real possibility.

 

These aren't complex formulas. CHT rise in this example should occur at a rate that generates 500° CHT about 5 minutes after Emergency power is applied for average atmospheric conditions (all engine types) and airspeed (air cooled engine). Reduce the power or the temperature continues to climb and the detonation effects begin to occur. Set hard time above 500° and/or temperature limits for the initial power loss and the progression to ever increasing effects.

 

1 minute above 500° or CHT = 510° the first power loss occurs.

2 minutes above 500° or CHT=520° permanent damage occurs and power loss extends to all power settings above normal cruise

3 minutes above 500° or CHT=530° power loss extends to all power settings and the engine begins to combust the lubricating oil. Engine failure will occur when oil temperature increases and the oil loses its ability to protect the engine from itself.

 

Engine limits must be respected as written but the effects are not random. In my real world experience, this would be an adequate simulation of the way it actually works.

 

 

 

 

 

This is the right direction, the problem with the specific numbers you state though is that there is no evidence that destructive overheats would necessarily occur if you left WEP on for 8 minutes instead of 5. In fact, as has been pointed out myriad times there is much evidence that these engines could and frequently did go significantly longer than the manual limit without failure. So to implement this solution correctly you couldn't just say "Engine overheat begins after five minutes", you would need to figure out some plausible figures for how long it *actually* takes a given aircraft to overheat at a given power setting at certain atmospheric conditions. A tough undertaking.

Or you could just give everything about 10-15 minutes of WEP, which would fix about 85% of the logical inconsistencies and problems and get us much closer to how these things were actually flown in combat while consuming almost no man-hours.

Edited December 13, 2018 by Rattlesnake

[Sgt_Joch]

32 minutes ago, Rattlesnake said:

The problem with the "It's the higher octane!" explanation is that if 1.42 ATA was really pushing the detonation threshold with the fuel the Germans used then it could easily cause problems immediately,  it wouldn't wait around exactly one minute every time before problems ensued. Certainly other nation's WEP time limits on similar engines weren't because detonation would always start soon after exceeding, they were based on encouraging pilots to not needlessly stress the engines. If octane is the explanation we were rolling with I would like to see proof that 1.42 ATA was riding the detonation threshold and that this was indeed the reason for the limitation.

 

yes, 1.42 was close to the detonation threshold.

 

That is why when the compression ratio was bumped up on the DB605 in the G series using the same 87 octane fuel, you started to see immediate problems of detonation, i.e. pistons burning through:

 

http://kurfurst.org/Engine/Boostclearances/DB605_142ban_June1942.html

 

That is the reason why the DB605 was limited to a max ata of 1.3 until late in 1943.

Quote

 

That still leaves us with the "combat power" problem. Obviously a setting which can be run for 30 minutes at a time is way below the immediate detonation threshold. So I say again, what is the logic behind a hard limit on the DB but not the Klimov when the former is running at lower boost, RPMs, and output?

 apples and oranges. a 95 octane fuel allows you to run at a much higher boost than a 87 octane one.

 

when the RAF switched from 87 octane to 100 octane fuel, they bumped up the boost on the Spitfire from +6 lbs to +12 lbs max.

 

An increase of +6 lbs is equivalent to roughly 0.40 ata. The difference in going from 1.30 ata at 87 octane to 1.37 ata at 95 octane is only an extra +1 lb of boost which is easily justifiable by the use of fuel with a higher octane level. Basic Chemistry.

Quote

 

It still looks like the major difference between the DB and the Klimov limitations is only that the manual writers for the former were trying to encourage pilots towards practices that would extend engine life.

 

  no, see above.

Edited December 13, 2018 by Sgt_Joch

[Ehret]

Would high G-loads affect the engine is such way that damage would incur at prolonged WEP like settings?

[Panthera]

44 minutes ago, Sgt_Joch said:

That is the reason why the DB605 was limited to a max ata of 1.3 until late in 1943.

 

And by August it was cleared for 1.42ata after the oil cooling system, piston heads and possibly other elements were redesigned. You simply don't clear a boost setting that will result in issues with detonation after 1, 5 or even 10 min of use. The very idea is nonsensical to put in a nice way.

 

And indeed according to the manuals the engines cleared for 1.42ata had no time limits imposed upon them at all. 

 

That you keep ignoring this is indicative of you pushing a very biased agenda. 

[Sgt_Joch]

1 minute ago, Panthera said:

 

And by August it was cleared for 1.42ata after the oil cooling system, piston heads and possibly other elements were redesigned. You simply don't clear a boost setting that will result in issues with detonation after 1, 5 or even 10 min of use. The very idea is nonsensical to put in a nice way.

 

it was not fully cleared until october 1943, in fact according to some sources it is not clear the problem was ever fully resolved

1 minute ago, Panthera said:

 

And indeed according to the manuals the engines cleared for 1.42ata had no time limits imposed upon them at all. 

 

no, the actual manuals that still exist specified a 1 minute limit.

 

the argument that the engine was blocked at a max ATA of 1.3 due to detonation issue, and then with the same 87 octane fuel, 1.42 could be run for an unlimited time is ludicrous.

1 minute ago, Panthera said:

 

That you keep ignoring this is indicative of you pushing a very biased agenda. 

 

childish.

 

you don't want to discuss, don't post.

[Panthera]

22 minutes ago, Sgt_Joch said:

t was not fully cleared until october 1943, in fact according to some sources it is not clear the problem was ever fully resolved

 

What sources? If there is no limit in the manuals past August 43 then it's very clear.

 

22 minutes ago, Sgt_Joch said:

no, the actual manuals that still exist specified a 1 minute limit.

 

There is no manual for 1.42ata cleared engines listing a 1 min limit. They are all for engines banned from running at 1.42ata.

 

22 minutes ago, Sgt_Joch said:

the argument that the engine was blocked at a max ATA of 1.3 due to detonation issue, and then with the same 87 octane fuel, 1.42 could be run for an unlimited time is ludicrous.

 

No it isn't, because detonation is not all about the octane rating of the fuel, the design of the engine itself is important here. Ludricrous is clearing a boost rating that the engine cannot run at without detroying itself (!), that you're even suggesting this was done makes it very clear you are not an engineer.

 

22 minutes ago, Sgt_Joch said:

childish.

 

you don't want to discuss, don't post.

 

Childish is to ignore obvious evidence contrary to ones own wish of how things "should" be, which is all I've seen you do so far. 

 

Also I am not the one who doesn't want to discuss, hence why I don't arrogantly brush things off with "it's already been dealt with".

 

Yikes man!

Edited December 13, 2018 by Panthera

[Rattlesnake]

1 hour ago, Sgt_Joch said:

 

yes, 1.42 was close to the detonation threshold.

 

That is why when the compression ratio was bumped up on the DB605 in the G series using the same 87 octane fuel, you started to see immediate problems of detonation, i.e. pistons burning through:

 

http://kurfurst.org/Engine/Boostclearances/DB605_142ban_June1942.html

 

That is the reason why the DB605 was limited to a max ata of 1.3 until late in 1943.

 apples and oranges. a 95 octane fuel allows you to run at a much higher boost than a 87 octane one.

 

when the RAF switched from 87 octane to 100 octane fuel, they bumped up the boost on the Spitfire from +6 lbs to +12 lbs max.

 

An increase of +6 lbs is equivalent to roughly 0.40 ata. The difference in going from 1.30 ata at 87 octane to 1.37 ata at 95 octane is only an extra +1 lb of boost which is easily justifiable by the use of fuel with a higher octane level. Basic Chemistry.

  no, see above.

The problems of a different engine do not necessarily apply to the one under discussion, so more evidence is needed. If the Germans authorized a setting which was in real danger of causing immediate detonation then this was an interesting and sort of unique thing to do, the WEP settings for other nations are clearly below this threshold. And if 1.42 ATA was in no danger of causing detonation at 59 seconds of use then there is no reason to think it would start being in danger of doing so after 69-99 seconds, unless a sharp temperature rise is involved. (If that engine setting really overwhelmed the ability of the cooling system to keep up after about a minute of use, that's very interesting. Model it, instead of giving us a hard timer.) 

And as to the combat power thing, again this is not how octane and detonation work. An engine setting that can be run for half an hour with a given fuel *without* causing detonation doesn't suddenly start causing detonation when that arbitrary number of minutes is exceeded. And other than allowing a higher threshold for detonation higher octane fuels aren't "easier" on engines.

Again, the "combat" half hour limitation on the 109 seems clearly to have been written to encourage pilots to avoid putting wear and tear on the engine outside of war necessity, and does not imply any absurd notion that the thing would fail if you ran it like that 33 minutes instead of 30.

Edited December 13, 2018 by Rattlesnake

[Sgt_Joch]

41 minutes ago, Panthera said:

 

No it isn't, because detonation is not all about the octane rating of the fuel, the design of the engine itself is important here. Ludricrous is clearing a boost rating that the engine cannot run at without detroying itself (!), that you're even suggesting this was done makes it very clear you are not an engineer.

 

 

Childish is to ignore obvious evidence contrary to ones own wish of how things "should" be, which is all I've seen you do so far. 

 

Also I am not the one who doesn't want to discuss, hence why I don't arrogantly brush things off with "it's already been dealt with".

 

Yikes man!

 

stop acting like a spoiled brat or assigning motives to other people or indulging in ad hominem attacks. This is a flight sim forum, we are all here for the same thing, to have these airplanes modeled the most realisticaly way possible.

 

1. the argument that the 1.42 limit on the DB605 was lifted forever is just that, an argument, some people believe it, some people don't, so don't act like it is settled it is not. There is evidence on both sides of the argument. It is obvious what side of the argument the Devs come down on.

 

2. the argument whether engine operating limits are there to prevent engine damage/failure or ease maintenance or a mix of both and how close the limits set out in the manual are to the real limits has been going on forever. I was having the same arguments in the 80s when we were playing board games. If the answer was obvious, it would have been settled a long time ago.

 

If all these subjects were as clear as some of you guys think it is, we would not need a forum. 

[Gambit21]

Joch doing what you’re accusing him of doing isn’t helping your case or this thread.

 

Lets not get it locked.

[Panthera]

42 minutes ago, Sgt_Joch said:

1. the argument that the 1.42 limit on the DB605 was lifted forever is just that, an argument, some people believe it, some people don't, so don't act like it is settled it is not. There is evidence on both sides of the argument. It is obvious what side of the argument the Devs come down on.

 

I'm not acting like anything is settled Joch, saying things such as "it's already been dealt with" however is acting exactly like that.

 

Also if you trust so much in the devs decision in this case then I wonder where that same trust went when it comes to the limits on Allied engines? It gets real tiring reading the same double standards from certain people over and over again.

 

 

[Guest deleted@83466]

Sgt. Joch, I wouldn't even bother with 'em anymore.

[Gambit21]

I support you in that endeavor.

[Panthera]

Yes, I think we've all said our piece on the matter now.

 

So it's time to move back to the issue with the R-2800. 

[Legioneod]

5 hours ago, Gambit21 said:

The real life chance of a Jug’s engine failing in WEP while it had water (15 min) is basically zero.

 

Therefore any percentage/failure mechanism should kick in at the 15:01 mark.

THIS. It really is a simple solution and should be the same for all water injected engines for the most part.

 

The P&W R2800 was one of, if not the most durable engines of the war. A factory fresh engine would not fail after just 15 min of WEP, it was designed to withstand much much more.

 

R2800s were boosted up to 150" (just for test) iirc do you really think an engine that can withstand that high boost will fail after just 15 min at a measly 64", no.

Edited December 13, 2018 by Legioneod

[NZTyphoon]

19 minutes ago, Legioneod said:

THIS. It really is a simple solution and should be the same for all water injected engines for the most part.

 

The P&W R2800 was one of, if not the most durable engines of the war. A factory fresh engine would not fail after just 15 min of WEP, it was designed to withstand much much more.

 

R2800s were boosted up to 150" (just for test) iirc do you really think an engine that can withstand that high boost will fail after just 15 min at a measly 64", no.

 

Just for interest, from page 218 of R-2800: Pratt & Whitney's Dependable masterpeice:

 

Quote

As an interesting footnote in the development of the R-2800, during World War II Frank Walker was charged with the task of testing the ADI system....When reports came through that 3000 horsepower had been achieved with the R-4630 he met that challenge by boosting the R-2800 to ever higher manifold pressures and feeding it with additional ADI fluid....When the 3800 horsepower threshold was achieved by the R-4630, Frank ran his R-2800 to a stratospheric 150 in. Hg to match....Frank had to call it quits at 3800 horsepower; it would have been a difficult explanation to make to his superiors if he had blown up his R-2800 in his test cell. What makes this story more remarkable is the fact that Frank's R-2800 was a lowly "B" engine!...As further endorsement of the R-2800's sound and rugged design, Frank made regular test runs of 3000 horsepower for one hundred hours.

 

On another note, it was possible to have "Turbo Collapse" or "Pulsation" through incorrect operation of the engine controls:

 

,

[Legioneod]

1 minute ago, NZTyphoon said:

 

Just for interest, from page 218 of R-2800: Pratt & Whitney's Dependable masterpeice:

 

 

On another note, it was possible to have "Turbo Collapse" or "Pulsation" through incorrect operation of the engine controls:

 

,

Turbo collapse and pulsation aren't modeled in-game, though they should be.

[LLv34_Flanker]

S!

 

 There is no doubt the R-2800 is a rugged design. One of the most famous radials up to date! But if an engine is run in a test bench in pretty much static conditions instead of a plane going  from sea level up to 30,000ft and having varying levels of maintenance by the tech personnel, one can not take the test bench values as a gospel how things should be in a game. Not for any plane of any nation. You can get guidelines how it might perform under certain conditions. Same applies on how people say the .50cal is accurate. It is very much so, in static conditions like when shooting from a fixed mount or similar. When installed on a plane the accuracy drops due many factors like wing flex, vibrations, speed and wind etc. that are pretty much non-existent in test conditions.

 

 We have these stupid timers in the game no-one likes, except the devs maybe. There have been numerous reports or writings how personnel and pilots pushed the limits of the engines. Like R-2800 being field modded for higher MAP or Sachsenberg´s FW190D-9 that had a souped up Jumo 213E because his techie was very professional with engines etc. and all seemed to work pretty well. Helmut Lipfert quite well describes in his book how he chases down a La-5F/FN in his Bf109G-6 at full power and radiators closed. Only things he was worried about were OIL and COOLANT temperatures, not the clock or counting seconds. As long as these 2 values were within tolerances he could push the engine to it´s limits. He did and caught the La-5 shooting it down. Sure it shortened the time required between overhauls, but it did not result in a catastrophic failure after one minute, like in the game. Same applies to Jugs over ETO, some were souped up and performed well if limits were not exceeded blatantly. But it did shorten the overhaul period. And could be attributed to some losses due technical problems. Same with any other plane really.

 

IMHO the game should put more weight on monitoring engine values like temperature etc. rather than imposing artificial timers. A new approach on the whole engine durability issue. Make the pilot use the gauges and monitor how the plane behaves or face the consequences like overheating and blowing the engine, detonation etc. A believeable engine management modelling is as important as a good FM or DM.

[=362nd_FS=RoflSeal]

The Devs have said that they model only factory fresh aircraft, reality is this only applies to the airframe.

[Rattlesnake]

6 hours ago, LLv34_Flanker said:

S!

 

 There is no doubt the R-2800 is a rugged design. One of the most famous radials up to date! But if an engine is run in a test bench in pretty much static conditions instead of a plane going  from sea level up to 30,000ft and having varying levels of maintenance by the tech personnel, one can not take the test bench values as a gospel how things should be in a game.

People keep saying "It was a bench test!" in a talismanic manner. Well that's not an argument. You have to come up with physical reasons why the engine would have vastly better endurance on the bench and demonstrate that those reasons were in fact a variable in the tests if you want to pick apart the results.

And anyway, no one is suggesting that the R-2800 in the game be able to run at over 100" for hours or the like. But 15 minutes at 64" is so far short of tests the engines have successfully endured that believing a real R-2800 in good condition mounted on a real P-47 couldn't handle it the vast majority of the time is ludicrous.

[=362nd_FS=RoflSeal]

On 12/13/2018 at 4:06 PM, Sgt_Joch said:

 

if you fly a realistic length mission with the Yak-1, you would only fly at 100% in combat since you want the engine to be as cool as possible once you enter combat and the engine burns a prodigious amount of fuel at 100%. As I recall, 10 minutes or so at 100% would burn off around 140 liters or 35% of the total fuel capacity.

And the Bf-109 at 1.42 ata, P-39 at 51 "Hg, P-47 at 64 "Hg haven't got high fuel flow rate?

You are just proving that removing artificial manual suggestions would still leave the pilots having to regard for their fuel consumption 

Edited December 14, 2018 by RoflSeal

[Sgt_Joch]

7 minutes ago, RoflSeal said:

And the Bf-109 at 1.42 ata, P-39 at 51 "Hg, P-47 at 64 "Hg haven't got high fuel flow rate?

You are just proving that removing artificial manual suggestions would still leave the pilots having to regard for their fuel consumption 

 

no, I was responding to your comment about the Yak-1 and showing that it was wrong.

 

if you guys really want me to come back into this debate, continuing to quote me is the way to go. 

Edited December 14, 2018 by Sgt_Joch

[=362nd_FS=RoflSeal]

5 minutes ago, Sgt_Joch said:

 

no, I was responding to your comment about the Yak-1 and showing that it was wrong.

 

if you guys really want me to come back into this debate, continuing to quote me is the way to go. 

You proved absolutely nothing your comment.

[Sgt_Joch]

1 minute ago, RoflSeal said:

You proved absolutely nothing your comment.

 

I dont even understand what you are saying?

 

maybe if you draft a intelligible sentence?

[=362nd_FS=RoflSeal]

5 minutes ago, Sgt_Joch said:

 

I dont even understand what you are saying?

 

maybe if you draft a intelligible sentence?

Maybe you should look at yourself.
I'm not the acting as if the Yak is the only aircraft with thermal limits.

Edited December 14, 2018 by RoflSeal

[Sgt_Joch]

17 minutes ago, RoflSeal said:

I'm not the acting as if the Yak is the only aircraft with thermal limits.

 

I never said it was, now did I?

 

I merely pointed out that your comment that the Yak would fly at 100% all the time was wrong.

 

Maybe that is the way it is flown on the air quake servers where sorties last 10 minutes, but no self respecting Yak jockey would fly that way in a realistic mission. First, your engine would overheat and you would be forced to slow down and second, you would run out of gas after 25 minutes.

 

..and for the record, I don't agree with the strict manual timers method anymore than anyone else and will be as happy as everyone else when and if the Devs implement a more realistic method. I just think removing all limits altogether would be a major step backwards.

Edited December 14, 2018 by Sgt_Joch

[=362nd_FS=RoflSeal]

12 minutes ago, Sgt_Joch said:

 

I never said it was, now did I?

 

I merely pointed out that your comment that the Yak would fly at 100% all the time was wrong.

 

Maybe that is the way it is flown on the air quake servers where sorties last 10 minutes, but no self respecting Yak jockey would fly that way in a realistic mission. First, your engine would overheat and you would be forced to slow down and second, you would run out of gas after 25 minutes.

Okay
 

Quote

 

4. it is not true that the Yak-1 engine has no limits, there is a thermal limit. The Yak-1 engine runs hot at 100% throttle/RPM and can easily overheat. If the overheating is not addressed, the engine will fail very quickly.

 

Here is you acting as if the Yak-1 is the only aircraft that has thermal limits. Nice example of trying to change the goalposts as well. When we talk limits we all know we are referring to the arbitrary time limits that are completely un-monitered by any of the steam gauges we have in the cockpit.

Have we used 3:30 of emergency power or 4 minutes? I don't know. I need techno-chat to tell me I have exceeded the allowed time, anything else is a gut feeling. I don't need technochat to monitor whether I am above 115C or not.

Edited December 14, 2018 by RoflSeal

[Sgt_Joch]

12 minutes ago, RoflSeal said:

 

Here is you acting as if the Yak-1 is the only aircraft that has thermal limits. Nice try trying to change the goalposts. 

 

well if you had read the whole post, you would see that I was replying to the notion that the Yak-1 should not be able to run at 1.37 ata with no prescribed limit. The subject was the Yak-1, not any other airplane, so why would I have discussed other planes? no, I am not moving the goalposts. 

 

anyway this is getting off topic again. let's move on.

Edited December 14, 2018 by Sgt_Joch

[LLv34_Flanker]

S!

 

 Test bench is a test bench. The engine is not subjected to extreme cold, pressure variations etc. It always has sufficient cooling and some used special propellors too. And the engines were meticulously inspected at test facility, even having their oil changed between runs etc. Take an engine from the field and it will yield different results, depending how well it was maintained etc. Maintenance or lack of it can make one helluva difference.

 

 Again R-2800 is a rugged engine, no denial on that. But some seem to refer to these test runs and think that it should be able to pull insane stunts just because it was tested on 100" or more. I agree it should be able to easily take the rated power within the limits, without damage. Of course pilot has to take care of proper procedures to keep the engine within those parameters. Add to the mix the missing things like turbo collapse and fluctuation. Then it would get interesting. 

 

Same should apply to any engine really. Stay within temperature and other rated parameters and the engine should be able to shrug off some high power settings without blowing to pieces after an artificial timer. In game we do not suffer from contaminated or low grade fuel, bad lubricants, bad maintenance, faulty spark plugs, worn out valves and pistons or any other issues that could affect the engine negatively. Always factory fresh according to the devs. More so the engines should be able to run on high power without blowing up..

 

 

[Rattlesnake]

3 hours ago, LLv34_Flanker said:

S!

 

 Test bench is a test bench. The engine is not subjected to extreme cold, pressure variations etc. It always has sufficient cooling and some used special propellors too. And the engines were meticulously inspected at test facility, even having their oil changed between runs etc. Take an engine from the field and it will yield different results, depending how well it was maintained etc. Maintenance or lack of it can make one helluva difference.

 

 Again R-2800 is a rugged engine, no denial on that. But some seem to refer to these test runs and think that it should be able to pull insane stunts just because it was tested on 100" or more. I agree it should be able to easily take the rated power within the limits, without damage. Of course pilot has to take care of proper procedures to keep the engine within those parameters. Add to the mix the missing things like turbo collapse and fluctuation. Then it would get interesting. 

 

Same should apply to any engine really. Stay within temperature and other rated parameters and the engine should be able to shrug off some high power settings without blowing to pieces after an artificial timer. In game we do not suffer from contaminated or low grade fuel, bad lubricants, bad maintenance, faulty spark plugs, worn out valves and pistons or any other issues that could affect the engine negatively. Always factory fresh according to the devs. More so the engines should be able to run on high power without blowing up..

 

 

In one sentence you say the engine would last longer on the bench because it is not subjected to extreme cold. In the next sentence you say the engine would last longer on bench because it would always have sufficient cooling. (BTW, isn't a ~250mph wind at chilly high altitudes fairly cooling of anything exposed to it?) So this is awkward...

And weren't the propellers used for engine tests designed to replicate the loads of actually powering an airplane? It wouldn't be a good test otherwise.

I believe it is the stated position that the planes modeled in the game are always factory fresh so we can rule incompetent maintenance out as a wildcard.

So I repeat, there is no reason to suspect that an R-2800 shouldn't be able to run at 64" for the whole 15 minutes it has water to do so, and much reason to suspect it *not* being able to do so is absurd.

[NZTyphoon]

 

 

3 hours ago, LLv34_Flanker said:

Again R-2800 is a rugged engine, no denial on that. But some seem to refer to these test runs and think that it should be able to pull insane stunts just because it was tested on 100" or more. I agree it should be able to easily take the rated power within the limits, without damage. Of course pilot has to take care of proper procedures to keep the engine within those parameters. Add to the mix the missing things like turbo collapse and fluctuation. Then it would get interesting. 
 

Nobody, including me, is saying that the R-2800 "...should be able to pull insane stunts...". If you read my post properly I wrote "Just for interest" to indicate that I was not commenting on the game, but was citing a source confirming that the R-2800 was run at such extreme boost pressures and horsepower ratings.

 

 

Edited December 14, 2018 by NZTyphoon

[Rattlesnake]

5 hours ago, Sgt_Joch said:

 

well if you had read the whole post, you would see that I was replying to the notion that the Yak-1 should not be able to run at 1.37 ata with no prescribed limit. The subject was the Yak-1, not any other airplane, so why would I have discussed other planes? no, I am not moving the goalposts. 

 

anyway this is getting off topic again. let's move on.

You attempted to use higher octane fuel as a reason why the Klimov can run indefinitely a given setting (assuming you can keep it cool), whereas the DB, a physically similar engine, is limited to 30 minutes at the somewhat less stressful settings called "combat" in this game. In order for this answer to make sense you must explain why the 87 octane fuel powering said DB engine is sufficient to protect from detonation at "combat" power for exactly 30 minutes, but insufficient thereafter, justifying a hard timer.

 

[Ehret]

10 minutes ago, Rattlesnake said:

You attempted to use higher octane fuel as a reason why the Klimov can run indefinitely a given setting (assuming you can keep it cool), whereas the DB, a physically similar engine, is limited to 30 minutes at the somewhat less stressful settings called "combat" in this game. In order for this answer to make sense you must explain why the 87 octane fuel powering said DB engine is sufficient to protect from detonation at "combat" power for exactly 30 minutes, but insufficient thereafter, justifying a hard timer.

 

IMO those rating have other a much more mundane explanation. At average a VVS pilot had short life expectancy in combat. Why then care about prolonging TBO when the whole machine would get wrecked, shortly? Just make more of them, crew them with cannon fodder and send to the front.

Similar stuff happened to the LW later in the war. If it's likely you are going to be shot down in a week then the notion of counting minutes just to extend the engine TBO is ridiculous.

[Rattlesnake]

4 minutes ago, Ehret said:

 

IMO those rating have other a much more mundane explanation. At average a VVS pilot had short life expectancy in combat. Why then care about prolonging TBO when the whole machine would get wrecked, shortly? Just make more of them, crew them with cannon fodder and send to the front.

Similar stuff happened to the LW later in the war. If it's likely you are going to be shot down in a week then the notion of counting minutes just to extend the engine TBO is ridiculous.

In other words there is no physical reason whatsoever that the engine should be expected to fail at this setting when an arbitrary 30 minutes has elapsed. Thank you.

[Ehret]

1 hour ago, Rattlesnake said:

In other words there is no physical reason whatsoever that the engine should be expected to fail at this setting when an arbitrary 30 minutes has elapsed. Thank you.

 

There are only odds and IRL combat pilots had to prioritize dangers. Assuming the engine was in good condition a seizure was unlikely. Getting shot at and killed in under-performing plane was much more threatening. If you were flying over your own territory even more so; it's perfectly fine to save yourself (or others) at a cost of scrapped engine.

The priorities could change if you were flying long missions over the enemy territory or sea. Still, if you were in position getting killed within next few minutes then it'd be better to escape the immediate danger even if you had to ditch afterwards. A remote chance of survival is preferable to none.

 

IMHO "limits" stated in manuals reflects just that - the higher expected survival ratios the more conservative settings in papers.

Edited December 15, 2018 by Ehret

[Rattlesnake]

18 minutes ago, Ehret said:

 

There are only odds and IRL combat pilots had to prioritize dangers. Assuming the engine was in good condition a seizure was unlikely. Getting shot at and killed in under-performing plane was much more threatening. If you were flying over your own territory even more so; it's perfectly fine to save yourself (or others) at a cost of scrapped engine.

The priorities could change if you were flying long missions over the enemy territory or sea. Still, if you were in position getting killed within next few minutes then it'd be better to escape the immediate danger even if you had to ditch afterwards. A remote chance of survival is preferable to none.

 

IMHO "limits" stated in manuals reflects just that - the higher expected survival ratios the more conservative settings in papers.

What if I told you strictly by the book limits would be more defensible if there was some sort of mechanic other than a suddenly blown engine for exceeding them? For instance automatic shut-off of WEP when time is exceeded or some temperature on a gauge (not exactly how it really worked usually, but it's easy to monitor and manage)? But with an "Oops, you forgot to count minutes in a dogfight and now your engine is dead mechanic" we have reason to get beyond the book start asking question about plausible real world time scales for damage.

[Panthera]

24 minutes ago, Ehret said:

IMHO "limits" stated in manuals reflects just that - the higher expected survival ratios the more conservative settings in papers.

 

Seems like a pretty far fetched connection to make...