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Talon_

Water injection inconsistency between K-4 and P-47D

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7 minutes ago, Mosler said:

oh i havent seen them, same engine?

 

R-2800-59W. In fact the 70 hour WEP test was at even higher manifold pressure than we have.

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I don't think you can find anybody who disagrees with a more thorough, realistic modelling of engine fatigue. Though separating combat/emergency timers etc would be nice to have on all planes, not arbitrarily given out. Tbh I think it is a better system than the combined timers, but either way it has to be consistent.

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Yeah, maybe the manuals says 5 min for the 47 and 10 for the 109 because they didnt want the pilots to run out of wep in one go i dont know maybe someone knows the reason for that, but if theres is proof of the 47 lasting that much in wep it should be like that.

Edited by Mosler

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Tests by Rolls Royce showed early Merlin 66 tended to die after 27hrs of continuous WEP.  Modifications were made until RR was getting 100hrs with one engine doing 100hrs continuous WEP on a bench before doing another 100 hrs WEP flying without servicing. 

 

It's the height of silliness now where a DB605DC can do 45 minutes of continuous ADI/WEP at boost pressures we're not sure it even used,  and yet the Merlin 66 will blow in 6 minutes. 

Edited by Bloodsplatter
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11 hours ago, Talon_ said:

Just to clarify with the current physics the Bf109 can use the water injection this way:

 

WEP 1.98 10m

Combat 1.6 10m

WEP 1.98 10m

Combat 1.6 10m

WEP 1.98 5m

Total time spent outside Continuous: 45m

 

After this it runs out of water (but only has a few minutes of fuel left anyway).

 

This is shown in the Streamable link in the OP.

Shouldn't the combat power limit be 1.45 ATA, or does the DC engine increase that limit?

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10 minutes ago, 71st_AH_Barnacles said:

Shouldn't the combat power limit be 1.45 ATA, or does the DC engine increase that limit?

 

Honestly I don't know. I don't believe a "combat" limit was set in the DC manual. It does seem silly compared to all the other engines in the game though.

 

I just posted my test results, the methodology of which is visible in the OP streamable links :salute:

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At least, with the way they have the engine damage in the game, it really makes people become invested in researching historical engine limits. Every day's a school day.

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17 hours ago, -=PHX=-SuperEtendard said:

I tested how the Emergency Power affects the Combat Power remaining time and found that it affects most planes, but mostly the planes that share the same RPM settings for both modes:

P-39L1: After using 5 minutes of 51" at 3000 RPM only, it is left with just 1 (!!!) minute of combat power at 42" at 3000 RPM (rated for 15 min), after that damage to the engine happens around 2 mins later.

P-40E: After using 2 minutes of 45.5" at 3000 RPM only, it is left with around just 30-40 seconds of combat power at 42" 3000 RPM (rated for 5 min).

Spitfire Mk Vb: After using 3 minutes of +16 boost at 3000 RPM, it is left with 20 minutes of combat power at +9 boost 2850 RPM (rated for 30 min).

Fw 190 A-8: After using 10 minutes of 1.58 ata at 2700 RPM, it is left with 15 minutes of combat power at 1.32 ata 2400 RPM (rated for 30 min).

I don't remember this was like this in previous versions. I have played with the P-39, using plenty of 51" power during fights, then switching back to 42" without much trouble, never got an engine damage because of consumed engine timer... could this be a bug that came with this 3.007 update?

Not only is troublesome for the P-47, but for planes like the P-39 or P-40 this is much worse.

 

 

Can anyone conclusively say that it never worked like this before? As I posted it was my understanding that it has always been this way.

 

Also, it would be good to get some feedback on the MW50/47 disparity when it comes to boost timers here.

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2 hours ago, =RvE=Windmills said:

 

 

Can anyone conclusively say that it never worked like this before? As I posted it was my understanding that it has always been this way.

 

Also, it would be good to get some feedback on the MW50/47 disparity when it comes to boost timers here.


 @RoflSeal mentioned he could use for the P-40 the timers separately without problems in the past.

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Why is this in the bug report section?

 

Also, what's the current reset timer between WEP uses? I've never actually been able to use WEP more than once without my engine blowing.

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3 minutes ago, Legioneod said:

Why is this in the bug report section?

 

Also, what's the current reset timer between WEP uses? I've never actually been able to use WEP more than once without my engine blowing.

 

It varies from plane to plane, it's usually 5-15-20 minutes at continuous, some planes can do it in Combat mode (109, Spitfire for example).

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23 minutes ago, -=PHX=-SuperEtendard said:

 

It varies from plane to plane, it's usually 5-15-20 minutes at continuous, some planes can do it in Combat mode (109, Spitfire for example).

Where do they come up with these arbitrary numbers?

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On 11/24/2018 at 8:22 PM, Legioneod said:

Fact is it shouldn't work like that in-game, engine failure shouldn't happen after 5min of WEP. 

WEP limitations are to preserve the life of the engine over the course of a long period of time, not two minutes after going over WEP.

 

The R2800 passed the 7 1/2 hour testing at 65" WEP and did not fail, there is literally no reason for the engine to fail in-game besides some sort of balance and simplified engine model.

 

Either give us the full 15 min of WEP or decrease the time required between uses to a useable level, currently I waste most of my water due to the fact I can't even use it due to engine failure.

 

American aircraft suffer the most from the gamey engine model of this sim.

Correct the government testing required 7.5 hrs at WEP but Pratt & Whitney routinely ran its engines for 100 hours straight at War Emergency Power that include the R2800 

http://www.enginehistory.org/Biography/FrankWalkerWeb1.pdf

Edited by ATAG_dB
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13 minutes ago, ATAG_dB said:

Correct the government testing required 7.5 hrs at WEP but Pratt & Whitney routinely ran its engines for 100 hours straight at War Emergency Power that include the R2800 

http://www.enginehistory.org/Biography/FrankWalkerWeb1.pdf

Yep, it's very odd to me that they chose 5 min only. I understand that's what the manual states, but manuals arent the sole authority on engine limits.

If the R2800 quit after going over 5min of WEP I'm sure there would be alot less P-47s surviving the war.

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To my knowledge it was the most robust piston engine ever build.

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3 hours ago, Legioneod said:

Yep, it's very odd to me that they chose 5 min only. I understand that's what the manual states, but manuals arent the sole authority on engine limits.

If the R2800 quit after going over 5min of WEP I'm sure there would be alot less P-47s surviving the war.

This. 

 

It would be nice if the devs would deign to share whatever documentation they have to the effect that the R-2800-59W self-destructs when these arbitrary time limits are exceeded.  One can only assume such documentation would be plentiful and widespread considering the dire necessity of of reliable engine performance in combat.  

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They don't have documentation that the engine would blow up. They just decided 5 years ago to go with the time limits based on the handbook. 

 

Of course no engine would explode just because you run it for a longer time than the "official" time limits, but that has been dicussed hundreds of times already the past years and it's not like it's a new for the P-47.

 

BoX just desperately needs a complete redesign of how engine limitations are handled.

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1 minute ago, Matt said:

They don't have documentation that the engine would blow up. They just decided 5 years ago to go with the time limits based on the handbook. 

 

Of course no engine would explode just because you run it for a longer time than the "official" time limits, but that has been dicussed hundreds of times already the past years and it's not like it's a new for the P-47.

 

BoX just desperately needs a complete redesign of how engine limitations are handled.

 

Yeah, they never bothered to normalize engine durability, which is a shame.

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I think it shows most obviously in planes like the K-4, which can spend over 50% of a 45-minute sortie on WEP. If the timers are there to stop WEP abuse, what happens when the manuals start to allow it? Your timers don't balance out the power between aircraft anymore - you get a similar late-war plane like the P-47D not even able to use up all the water inside an hour of flight due to the 20-minute continuous power cooldown between WEP runs.

 

I'm serious, if you run the water for 5 minutes on takeoff you can't finish using water until the end of the 55th minute of flight.

 

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Just now, Matt said:

They don't have documentation that the engine would blow up. They just decided 5 years ago to go with the time limits based on the handbook. 

 

Of course no engine would explode just because you run it for a longer time than the "official" time limits, but that has been dicussed hundreds of times already the past years and it's not like it's a new for the P-47.

 

BoX just desperately needs a complete redesign of how engine limitations are handled.

 

I entirely agree.  And I believe the devs are entirely aware of all these facts.  This naturally leads me to wonder why they've chosen to nerf certain aircraft while buffing others in spite of historical evidence to the contrary.  

Just now, Talon_ said:

I think it shows most obviously in planes like the K-4, which can spend over 50% of a 45-minute sortie on WEP. If the timers are there to stop WEP abuse, what happens when the manuals start to allow it? Your timers don't balance out the power between aircraft anymore - you get a similar late-war plane like the P-47D not even able to use up all the water inside an hour of flight due to the 20-minute continuous power cooldown between WEP runs.

 

I'm serious, if you run the water for 5 minutes on takeoff you can't finish using water until the end of the 55th minute of flight.

 

Yeah, I'd also like to see documentation supporting this bizarre 20-minute cool down requirement.  But I'm not gonna hold my breath...

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well not defending the strict time limits used by the Devs, but looking into the 5 minute WEP limit for the P47, I think I can see why the U.S. Air force went with a more conservative setting. It seems that at 64" on 100 octane fuel, the P47 was already getting close to the detonation treshold.

 

-if you look at the july 44 test with 150 octane fuel, you see the test plane experienced detonation at 65" with water injection:

 

Quote

Preliminary tests were run to clear the airplane for performance with higher powers with and without water injection. Detonation equipment was installed to determine if any flight condition became marginal as to detonation, cooling or improper operation of auxiliary parts. No detonation was observed in level flight up to 65.0" Hg. without water and 70.0" with water. No detonation was observed in climb up to 65" Hg. without water. Detonation occurred at 65.0" with water in climb but was remedied by using a No. 18 water jet. Cylinder head and carburetor air temperatures remained below the limits in level flight. Excessive cylinder head and carburetor air temperatures were encountered in climbs, limiting the duration of any climb to a point where limits are reached.

 

the problem was resolved, but they were getting close to the limit and this was with 150 octane fuel, not the 100 we have in game. Notice also the problem with excessive heat.

 

http://www.wwiiaircraftperformance.org/p-47/p47-26167.html

 

-next: march 20, 1945 report showing that P47M were experiencing total engine failure after only 15-30 hours of operation. The engines had had severe detonation leading to burned out pistions. The cause seems to have been running the engines at 72" WEP, presumably on 150 octane fuel, but running sometimes without water injection:

 

p-47m-20march45.jpg

 

-next: 1946 test of a P47N showing that military power and WEP was putting a lot of strain on the engine:

 

Quote

At high power settings considerable maintenance was involved because of oil leaks, cracked vacuum pump housings, exhaust collector rings burning out and oil leaks. At war emergency power these malfunctions become excessive and operation was restricted at this power. In military power climbs high oil and cylinder head temperature above 30,000 ft. were experienced and made it necessary to reduce power after ten minutes of operation to cool the engine.

 

http://www.wwiiaircraftperformance.org/p-47/p-47n-88406.html

 

Again, not saying the engine could not be pushed past the limits shown in the manual, but those limits were not totally arbitrary.

 

another interesting thing I found out was on the water switch. It was not an on/off switch, the pilot apparently had to keep his finger on the switch the whole time which restricted his ability to do any type of combat maneuvering:

 

Quote

  The water control switch is objectionable because it must be held "on" by the pilot. This occupies the pilot's left hand and he cannot trim the plane or use both hands on the stick which is necessary to make a tight turn

 

http://www.wwiiaircraftperformance.org/p-47/p47-26167.html

Edited by Sgt_Joch

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The WEP limitations were in place to preserve the engine over the course of it's life, a factory fresh engine (which is what the game simulates) wont blow after 5 min of WEP, it wouldnt blow after 15min of WEP either since this wasnt even a fraction of the total required time for the engine to be able to handle WEP.

 

In regards to the P-47M failures it was due to the engine very poor condition after being shipped over to england and the fact the the USAAF was running them at 76" instead of the rated 72".

 

As for the detonation with 150 octane fuel at 65" this was resolved with a new water jet. 100 grade P-47s would have received this upgrade as well iirc once they started operating at 64".

 

I knew about the water switch as well and I'm thankful that they didnt implement it that way, I'd hate to have to hold the switch the whole time.

Earlier P-47s had a manual toggle switch that they didn't have to hold. And some blocks had automatic injection at certain throttle positions.

Edited by Legioneod
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3 hours ago, Sgt_Joch said:

-next: march 20, 1945 report showing that P47M were experiencing total engine failure after only 15-30 hours of operation. The engines had had severe detonation leading to burned out pistions. The cause seems to have been running the engines at 72" WEP, presumably on 150 octane fuel, but running sometimes without water injection:

 

The P-47M was rated for 72" WEP on regular fuel, and they were being pushed up to 76" with no work on what fuel was being used.

3 hours ago, Sgt_Joch said:

another interesting thing I found out was on the water switch. It was not an on/off switch, the pilot apparently had to keep his finger on the switch the whole time which restricted his ability to do any type of combat maneuvering:

 

Depends on the block, the later ones we have use a latched switch that you can see animating ingame.

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32 minutes ago, Talon_ said:

 

The P-47M was rated for 72" WEP on regular fuel, and they were being pushed up to 76" with no work on what fuel was being used.

 

I don't see that in the document I posted. They state that 18 P-47 engines self destructed from severe detonation/pistons burning through. Most of the cases are due to the the engine being run at 72" without intermittent water injection. The document mentions one engine where the self-destruction is due to being run at 76".

 

Are you referring to another document showing P47 engines self-destructing? I would like to see that.

32 minutes ago, Talon_ said:

 

Depends on the block, the later ones we have use a latched switch that you can see animating ingame.

 

I was under the impression the D-28 block we have in game works like that, i.e. you have to hold down the water injection switch continuously.

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5 hours ago, Sgt_Joch said:

I was under the impression the D-28 block we have in game works like that, i.e. you have to hold down the water injection switch continuously.

 

Yes, that's correct.

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8 hours ago, Sgt_Joch said:

 

I don't see that in the document I posted. They state that 18 P-47 engines self destructed from severe detonation/pistons burning through. Most of the cases are due to the the engine being run at 72" without intermittent water injection. The document mentions one engine where the self-destruction is due to being run at 76".

 

d. The 8th Air Force ran WER power checks on one airplane for 20 hours and then released it for WER operations at 76" Hg.

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3 hours ago, LukeFF said:

 

Yes, that's correct.

It's not modeled that way in-game.

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12 hours ago, Sgt_Joch said:

Are you referring to another document showing P47 engines self-destructing? I would like to see that.

 

 

Screenshot_20181127-135343.png

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7 hours ago, Legioneod said:

It's not modeled that way in-game.

 

I meant in reality, not the game. 

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