A funny thing happened on the way to 30,000 feet...........

[chris455]

P-47D-22. Took off from the runway at Hurne (?) England at 0615 hours. 100% fuel. No stores. 150 octane fuel. No other modifications. Flew due East. Set engine for climb at 2,000 ft/min.

I reached 30,000 ft  and decided to see what, if anything, had changed in the last update with the P-47. I made some lazy turns, and was enjoying watching my own contrails and monitoring instruments, when I noticed that my aux tank was now empty.

And my engine immediately quit.

Here is what I checked: 

• I was using technochat. Absolutely no "Engine 1 damaged" (or any other) messages.
• Cylinder head temp: Green
• Engine Oil Temp: Green
• Carb Air Temp: Green
• AUX Fuel tank: Empty
• Main fuel tank: Full
• Main Fuel tank Selector: MAIN 

I tried desperately to restart the engine by setting throttle, mixture, and RPMs in the appropriate positions and pressing "E", but all that would happen was the magnetos would go from OFF to ON. The engine would not start. I also tried to buy more time by feathering the prop, but curiously, the prop would not feather and technochat gave no clue why. I struggled with the fuel selector settings in "SETTINGS" (which I am under the impression do not work yet) and, well, they did not work. I rode her down to around 4,000 ft and bailed out, leaving my beautiful P-47 to crash into the woods in Southern England.

I HAVE NO CLUE WHAT HAPPENED HERE. I know that I ran out of gas in my AUX tank, but I had a full main tank. Shouldn't the sim have automatically switched the fuel supply? What else could have gone so wrong?

I would really like some hep figuring this out.............................

[BlitzPig_EL]

How many RPM were you running at?

 

Manifold pressure?

 

Turbo RPM?

Edited March 2, 2024 by BlitzPig_EL

[chris455]

Everything was per specs for unlimited. 

• 42"MAP
• 2600 RPM
• Did not check turbo RPM and I was using turbo, but only to boost MAP to 42". I don't think a blown turbo should have shut down the whole circus? (assuming I did overspeed it, which I doubt).

UPDATE:

While attempting to Monday-Morning Quarterback this flight, I attempted to repeat the engine failure phenomenon, but to save time, I started with a mostly-empty AUX tank.

When it ran dry, the sim did auto-switch to the MAIN setting on the fuel tank selector (as it had apparently before as well) and the engine hummed along withou a bauble.

I am going to repeat the first flight step-by-step and see if the problem persists. I will report back. 

In the interim, a couple of questions for the community:

• Is it even possible to feather the prop on a  single engine ship? I can't even select "ENGINE 1" on the P-47, and the Prop Feather command does not work either. No problem with multi-engine ships.
• Ha anyone ever overspeeded the turbo on a jug and got a failure or a technochat message about it? I am intrigued about this-

Edited March 2, 2024 by chris455
new info

[CountZero]

turn on instrument panel option, then youll see if engine timers run out, maybe you think your in safe specs but game does not, and as messages on when timer run out are buged you cant know when it run out or that you were even in danger.

[[CPT]Crunch]

No point in placing a feathering feature in a single engine prop fighter, nothing to be gained, your fubar anyway.  Generally feathering a prop is done through hydro-electrical mean, either or, or a combo of both.  That's only adding complexity and additional failure points, best to stick with chewing gum when it comes to fighter pilots.

[[CPT]Crunch]

That's actually a feature in many props, if prop oil pressure is lost a concentric ring will lock the prop in it's current position, good for preventing your motor mounts from being ripped off if the prop pitch suddenly reaches an extreme in pitch while entering a dangerous phase of flight. 

 

Many people don't understand moving the prop lever is only allowing the pilot a vote on his desired prop angle and RPM, there's plenty running behind the scenes depending on multiple factors that will set the actual blade angles and RPM's.

[LukeFF]

3 hours ago, [CPT]Crunch said:

No point in placing a feathering feature in a single engine prop fighter, nothing to be gained, your fubar anyway.  Generally feathering a prop is done through hydro-electrical mean, either or, or a combo of both.  That's only adding complexity and additional failure points, best to stick with chewing gum when it comes to fighter pilots.

 

The IAR 80 can feather its prop - easily the first time I've heard of that.

[FeuerFliegen]

6 hours ago, chris455 said:

Is it even possible to feather the prop on a  single engine ship? I can't even select "ENGINE 1" on the P-47, and the Prop Feather command does not work either.

 

Select manual prop pitch (if available) and then raise the prop pitch to 100%.  Most single engine planes aren't able to fully feather it, but they will be closer to that feathered position, giving you less drag; it will make a real difference.   The Bf109 E-7 is one of the only planes I know of that allows you to adjust the prop pitch to what appears to be a fully feathered position (and the IAR 80 according to LukeFF above; I don't have that plane yet though)

 

I hear people say there's absolutely no point in being able to feather a single engine plane, but there have been numerous times where I needed to do just that in order to glide as far as possible after an engine failure.

[Aapje]

Being able to glide further is certainly a benefit. It can be the difference between reaching friendly lines or a safe landing spot versus becoming a POW or crashing.

[chris455]

1 hour ago, FeuerFliegen said:

 

Select manual prop pitch (if available) and then raise the prop pitch to 100%.  Most single engine planes aren't able to fully feather it, but they will be closer to that feathered position, giving you less drag; it will make a real difference.   The Bf109 E-7 is one of the only planes I know of that allows you to adjust the prop pitch to what appears to be a fully feathered position (and the IAR 80 according to LukeFF above; I don't have that plane yet though)

 

I hear people say there's absolutely no point in being able to feather a single engine plane, but there have been numerous times where I needed to do just that in order to glide as far as possible after an engine failure.

.............and THIS is precisely why feathering should be included in ALL prop aircraft, single engine or no.

1 hour ago, Aapje said:

Being able to glide further is certainly a benefit. It can be the difference between reaching friendly lines or a safe landing spot versus becoming a POW or crashing.

Exactly. That why I am confused that the P-47 (and apparently other single-engine fighters) don't have it.

Edited March 3, 2024 by chris455

[chris455]

UPDATE:

I flew the mission again, exactly as before. This time however, based on an observation by BlitzPig EL, I carefully monitored my turbocharger speeds. Indeed, I am convinced the reason for the initial failure was turbine overspeed, which must have crept up past 22,000 RPM for too long. Also, I observed that the RPMs can indeed slowly increase with altitude irrespective of the position of the turbo lever. This, I believe, is how I met my Waterloo in this case. By insuring that I stayed below 20,000 RPM, I did not experience a repeat of the problem. I remain unconvinced that a blown turbo would cause a catastrophic engine failure, but I am an aerospace technical writer, not an aerospace engineer. Clearly this may be the way the sim treats this event when it occurs.

Thanks to all who responded with helpful information-

Chris

7 hours ago, CountZero said:

turn on instrument panel option, then youll see if engine timers run out, maybe you think your in safe specs but game does not, and as messages on when timer run out are buged you cant know when it run out or that you were even in danger.

Please tell me, what are these engine timers of which you speak? I have instrument panel option turned on, but I see no timers???

[CountZero]

Its message that will tell you exactly when game wonts you to stop using engine mode, they work only when you turn on also instrument panel, they will show up in techchat.

 

so if you fly at 2650 rpm and 42 inch your not in unlimited , your using combat engine timer, without instrument panel you dont know when game tells you you used it up, so you think your ok but your then in random engine fail time , and then all of suden your engine blows up with no reason and you dont know why, you report it as bug, you go search real life engine documents, you ask on forum... but main problem is engine timer just run out, and as tecchat messages that tells player when he should stop using that engine setting are buged , players dont know, simple bug but devs dont fix it

 

Engine modes:
Cruise (unlimited time): 2550 RPM, 42.0 inch Hg
Combat power (up to 15 minutes): 2700 RPM, 52.0 inch Hg
WEP (up to 5 minutes): 2700 RPM, 64.0 inch Hg

[AEthelraedUnraed]

On 3/3/2024 at 3:30 AM, chris455 said:

.............and THIS is precisely why feathering should be included in ALL prop aircraft, single engine or no.

In multi-engine aircraft, it can mean the difference between keeping flying on one engine, and having to make an emergency landing. In a single-engined plane, you have to ditch or bail anyway and all it does is give you a couple additional possible ditching spots to choose from. On the other hand, as Crunch says, it adds complexity which means more failure points, more expensive/lengthy maintenance, space requirements in the design, etc.

 

On 3/3/2024 at 3:42 AM, chris455 said:

Please tell me, what are these engine timers of which you speak?

In IL2, to simplify the whole engine/damage system, the effects of various things that can go wrong with an engine aren't usually modeled separately. As soon as you start running out-of-specs (e.g. too high RPM or MP; anything higher than "Continuous Power" from the in-game manual), a timer starts depending on how much out of specs you are. When the timer reaches 0, the engine fails. E.g. if your max allowed RPM is 3000 and you run 3100, you might get 10 minutes before the engine stops. If you run 3200, you might get 1 minute, etc.

[chris455]

 These timers, do they appear visually anywhere or in any way? Are these the symbols that appear at the right side of the screen in different colors?

Edited March 4, 2024 by chris455

[BlitzPig_EL]

Timers themselves are not visible.  All you see in tech chat is the state you are operating in.  Continuous, Combat, or Emergency.  Beyond that it's a guessing game.

[CountZero]

2 hours ago, BlitzPig_EL said:

Timers themselves are not visible.  All you see in tech chat is the state you are operating in.  Continuous, Combat, or Emergency.  Beyond that it's a guessing game.

if you turn on instrument panel option, then youll also see techchat message when timer expired and when it gets recovered. This is how you can be sure that you used up full time, and your not in random fail zone. And its only way to know when timer is ready to be reused fully.

 

Spoiler

 

 

Edited March 4, 2024 by CountZero

[chris455]

 This is very helpful, Count Zero. Thank you for sharing this-

[FeuerFliegen]

3 hours ago, chris455 said:

 This is very helpful, Count Zero. Thank you for sharing this-

 

Keep in mind that for some odd reason, in multiplayer, it will not tell you when your timer has expired.

[Beefs2]

On 3/2/2024 at 9:42 PM, chris455 said:

 I remain unconvinced that a blown turbo would cause a catastrophic engine failure, but I am an aerospace technical writer, not an aerospace engineer.

 

I'm pretty sure that a blown turbo needs a bypass vent to let the exhaust out or it all backs-up into the engine.  Think of the part that spins as a revolving door.  As the exhaust pushes its way out to drive the other side of the turbo which pushes fresh air in at increased pressure. If the exhaust has nowhere to go, there needs to be a vent before it gets to the turbo. I'm also pretty sure that IL-2's model has no built-in bypass procedure so.... cough, cough, choke.  (I'm not sure that the real thing had a bypass either but, I would figure the engineers that designed it had thought of that.)

 

Edit:  I just took a quick look at the P-47.  There are exhaust valves that open and close with the turbo handle settings.  They are right behind the oil cooler covers.  I think if you catch it fast enough once the turbo stops, the motor should stay running if you immediately pull the turbo back to zero. That's just a guess though.  

Edited March 5, 2024 by Anger_Birb

[Jaegermeister]

On 3/2/2024 at 9:42 PM, chris455 said:

I remain unconvinced that a blown turbo would cause a catastrophic engine failure, but I am an aerospace technical writer, not an aerospace engineer. Clearly this may be the way the sim treats this event when it occurs.

Thanks to all who responded with helpful information-

 

 

Although this is from Wikipedia, it does indicate that there were waste gates on the P-47 turbosupercharger. When the pressure reaches a certain point, it will vent through the waste gate. Turbos on cars usually have the same feature...

 

Quote as follows;

The cowling admitted cooling air for the engine, left and right oil coolers, and the turbosupercharger intercooler system. The engine exhaust gases were routed into a pair of wastegate-equipped pipes that ran along each side of the cockpit to drive the turbosupercharger turbine at the bottom of the fuselage, about halfway between cockpit and tail. 

 

[CountZero]

13 hours ago, FeuerFliegen said:

 

Keep in mind that for some odd reason, in multiplayer, it will not tell you when your timer has expired.

It works online, just servers dont have on Instrument Panel option in Realisam settings, so then you cant get them to display in techchat.

Devs need to first make it so they show up like 1000+ other messages when you only have tecchat option on, its clear bug as Instrument panel should have nothing to do with engine timers techchat messages. It would be like you have to have to also enable outside view with icons option , to be able to see icons on frendly airplanes... 

[1PL-Husar-1Esk]

46 minutes ago, CountZero said:

It works online, just servers dont have on Instrument Panel option in Realisam settings, so then you cant get them to display in techchat.

Devs need to first make it so they show up like 1000+ other messages when you only have tecchat option on, its clear bug as Instrument panel should have nothing to do with engine timers techchat messages. It would be like you have to have to also enable outside view with icons option , to be able to see icons on frendly airplanes... 

You are right but devs never address the issue, years now... and that addition information is IMHO easy to add opposite to resolving the whole engine timers issue.

Edited March 5, 2024 by 1PL-Husar-1Esk

[chris455]

I do enjoy this dialogue re: would a blown turbo kill the engine. I don't know if there is any means for the wastegates to open automatically, since these are controlled by the pilot via the turbo lever. 

A "blown turbo", as it applies to the P-47, meant that the bearings in which the turbo fans are  mounted have disintegrated due to overheat, and at that point, there would have to be a range of subsequent failures. These could include such things as the turbo fans upsetting and moving out of clock within the housing, the housing jumping out of it's mounts (I think it could happen), fire, etc. but I think the most likely outcome might be the seizure of the spinning components of the turbo and subsequent outgassing of the exhaust jet through which ever avenue presented itself (like a gaping hole in the housing, perhaps?), and if there were no outlet, an explosion of indeterminate severity. I can't state with certainty what would happen. I'm simply stating that a catastrophic engine loss would seem to be on the more dire end of possible outcomes. Not something that would occur in every instance.

Edited March 6, 2024 by chris455

[BlitzPig_EL]

Ingestion of various metal bits into the intake tract of the engine is never a good thing. 

[Jaegermeister]

9 hours ago, chris455 said:

I do enjoy this dialogue re: would a blown turbo kill the engine. I don't know if there is any means for the wastegates to open automatically, since these are controlled by the pilot via the turbo lever. 

A "blown turbo", as it applies to the P-47, meant that the bearings in which the turbo fans are  mounted have disintegrated due to overheat, and at that point, there would have to be a range of subsequent failures. These could include such things as the turbo fans upsetting and moving out of clock within the housing, the housing jumping out of it's mounts (I think it could happen), fire, etc. but I think the most likely outcome might be the seizure of the spinning components of the turbo and subsequent outgassing of the exhaust jet through which ever avenue presented itself (like a gaping hole in the housing, perhaps?), and if there were no outlet, an explosion of indeterminate severity. I can't state with certainty what would happen. I'm simply stating that a catastrophic engine loss would seem to be on the more dire end of possible outcomes. Not something that would occur in every instance.

 

Wastegates are normally set to open automatically, like a vent in a pressure cooker. According to the page in the P-47 Pilot's notes, overspeeding the turbosupercharger is acceptable for limited amounts of time.

 

 

Spoiler

 

 

A catastrophic failure of the turbosupercharger turbine would create some issues for sure, and would certainly reduce power significantly. It's not a small part. 

 

Spoiler

 

[LukeFF]

4 hours ago, Jaegermeister said:

According to the page in the P-47 Pilot's notes, overspeeding the turbosupercharger is acceptable for limited amounts of time.

 

What's interesting is that in the 1945 N-series manual, it's noted that turo overspeeding wasn't even considered to be an issue any more and hence why they integrated control of the turbo with the throttle.

[chris455]

13 hours ago, BlitzPig_EL said:

Ingestion of various metal bits into the intake tract of the engine is never a good thing. 

Agreed ................................and in the case of the P-47, next to impossible. Said bits would have to go through the intercoolers, carburetor, and supercharger before they ever had a chance of reaching the engine almost 20' away. But never say never! ?

Edited March 7, 2024 by chris455

[BlitzPig_EL]

You don't think something getting into the supercharger wouldn't create havoc with the engine?

[DD_Arthur]

When my Renault 18's turbo died it became a slower but much nicer car to drive.....

[jollyjack]

30000 feet, was curious 'bout that, seems about how high you can get in an IL2 jug. ... thought the horizon would be of a darker blue maybe ..

 

 

[chris455]

14 hours ago, BlitzPig_EL said:

You don't think something getting into the supercharger wouldn't create havoc with the engine?

Let's not oversimplify. 

You do realize we're not even discussing damage to the supercharger, right? The issue here is whether or not a failure of the turbocharger bearings, and subsequent mischief that would generate, would cause general engine failure. And my answer to that is, unlikely in the extreme.

Now to answer you question: If "something" (let's just call it FOD) got into the P-47's supercharger, it is entirely possible that it could lead to engine damage and/or possible failure. But that is not what we are talking about here. And remember that P-47s are known to have brought their pilot back to base missing entire cylinders. A damaged turbo? The engine just dies? I'm not buying it-

 

Edited March 8, 2024 by chris455

[BlitzPig_EL]

The simple damage modeling in the sim disagrees.  I agree with you about the real R2800, but we are dealing with a simulated one in the sim, where this kind of granular modeling simply doesn't exist.

[chris455]

11 hours ago, BlitzPig_EL said:

The simple damage modeling in the sim disagrees.  I agree with you about the real R2800, but we are dealing with a simulated one in the sim, where this kind of granular modeling simply doesn't exist.

Well, fortunately, it's easy enough to avoid at any rate. Thanks for helping me figure out what happened-?

[BlitzPig_EL]

Happy to help out!  

[Jaegermeister]

I thought ya'll might like this diagram to clarify a few things... #3 is the "supercharger" and #13, 15 & 16 is the "Turbocharger"

 

 

[Charon]

On 3/4/2024 at 6:36 PM, Anger_Birb said:

Edit:  I just took a quick look at the P-47.  There are exhaust valves that open and close with the turbo handle settings.  They are right behind the oil cooler covers.  I think if you catch it fast enough once the turbo stops, the motor should stay running if you immediately pull the turbo back to zero. That's just a guess though.  

In the D-series thunderbolts, the wastegates are regulated automatically based on exhaust backpressure. The turbo lever doesn't set wastegate position directly, it only sets the exhaust back-pressure to target (which indirectly relates to manifold pressure). If the turbine failed in such a way as to block exhaust -- I don't think that's a realistic failure mode, by the way -- but if it did, exhaust backpressure would increase and the wastegates would fully open automatically. Essentially the plane would revert to just the single-stage single-speed mechanical supercharger.

10 hours ago, Jaegermeister said:

I thought ya'll might like this diagram to clarify a few things... #3 is the "supercharger" and #13, 15 & 16 is the "Turbocharger"

This is good but appears to be for the M or N series Thunderbolts with the later electric turbo regulators and wastegates (Or perhaps not a P-47 at all?). D series is slightly different: the regulator operates off exhaust pressure, is mechanically linked to the wastegates, and is powered by hydraulic pressure.

 

On 3/6/2024 at 8:43 AM, LukeFF said:

What's interesting is that in the 1945 N-series manual, it's noted that turo overspeeding wasn't even considered to be an issue any more and hence why they integrated control of the turbo with the throttle.

Yeah, the regulator in the N series has automatic overspeed protection. There's some other stuff going on here as well, which is why N-series thunderbolts weren't able to switch to unilever control until they got the fancy Automatic Engine Control with the N-25.

 

On 3/7/2024 at 4:25 AM, BlitzPig_EL said:

You don't think something getting into the supercharger wouldn't create havoc with the engine?

I don't. There's essentially two parts to the turbo: the bucket wheel (lower half) and the impeller (upper half). Only the impeller is on the intake side of the engine.

 

Turbo overspeed is going to kill the lower half of the assembly first: the bucket wheels are hot (they're being blasted with exhaust gasses so are much hotter than the impeller) and under incredible centrifugal force at 22,000rpm. The most common failure mode is going to be that one of those buckets lets go and exits the turbo housing at very high speed. This isn't fatal to the turbo, the plane will still fly just fine, and it won't even leave any debris in the intake system to be ingested.

 

I don't have the reference for this handy, it's buried in ~4000 pages of microfilm I've got on my hard drive, but I'll try to track this down again later this evening and share it.

 

A seized bearing was mentioned above; I agree with @chris455 that it's probably just going to disable the turbo and result in the exhaust exiting through whatever hole it can find. I don't think it's going to cause further damage to the engine simply because the parts most likely to fail aren't actually on the intake side of the assembly. There might be a rear fuselage fire from all the heat, and I thought I remembered reading about such an accident, but I may be thinking of the accident that destroyed one of the prototypes (in which the tailwheel didn't retract and so caught fire). I'll search more later and see if I can find this reference.

Edited March 9, 2024 by Charon

[Charon]

Okay, I found the memos I was looking for, the most interesting bit being the minutes of a meeting held May 5 1943 at the USAAF Air Technical Section and a Sept 22 1943 memo regarding inspection of the P-47 Turbo bearings. The May 5th meeting is admittedly primarily concerned with other turbocharged planes (the P-47 had only just begun to see combat at this point), but the same principles should apply to the P-47s turbo.

 

https://user.fm/files/v2-e1a944761f17154e070c55e57ec205f2/turbosuperchargers.zip

 

Key points:

 

As I said above, the turbo can lose a bucket and the pilot wouldn't even notice:

Turbo overspeed does indeed lead to bucket failure:

 

A few cases of bearing failures and suspected turbo fires, but these seem to be rare. Various FOD removed from the intake ducts.

 

"Don't you think the failure of only the Turbo is the lesser of two evils?"

 

A separate memo dated 1943-09-22, concerning the P-47

Quote

b. Out of a total of 45(?) bearings inspected at (illegible), only one (illegible) evidence of overheating.

c. It is desired to point out too, that failure of subject bearings would not endanger the safety of flight as sufficient boost is available in the engine supercharger for medium altitude flight.

4. In view of the above (illegible) facts, it is strongly recommended that the inspection of supercharger bearings on P-47 aircraft be dispensed with.

Edited March 9, 2024 by Charon

[chris455]

Charon,

Thank you for this, I'm not simply gratified that your findings largely agree with my previous "gut feelings" but that you provided a level of technical granularity that I was not able to provide.

The idea that technical authorities recommended dispensing with bearing inspections altogether is grounds for the Devs to re-examine the engine timer that kills the R-2800 when the bearing is overspeed for too long, IMHO. I think your dissertation more than quashes the idea that a turbo casualty would routinely (indeed, if ever) lead to engine failure.

If it has any bearing, I was able to handily achieve 20,000 feet in the P-47 the other evening using only the mechanically-driven supercharger. To me, this stands as evidence that the Devs got way more right with the P-47 than they got wrong. And as far as the overall damage model of the Jug is concerned, I have to give the Devs two thumbs up.

 

Lots of great feedback from the community has arisen from my humble question that led to this thread. Way to go guys!

Edited March 9, 2024 by chris455

[BlitzPig_EL]

The 47 has come a long way from the days when a single 8mm round would stop it cold, that is for sure.

[chris455]

8 hours ago, BlitzPig_EL said:

The 47 has come a long way from the days when a single 8mm round would stop it cold, that is for sure.

You ain't kidding, Mister! ?