Manifold Pressure Regulator

[Wizard_03]

Why does the P47 in DCS not have a Manifold pressure regulator?

[grafspee]

56 minutes ago, Wizard_03 said:

Why does the P47 in DCS not have a Manifold pressure regulator?

If real P-47 haven't one, why DCS P-47 should have ?

[Wizard_03]

1 hour ago, grafspee said:

If real P-47 haven't one, why DCS P-47 should have ?

Does the real one not have one? 

[Stackup]

10 minutes ago, Wizard_03 said:

Does the real one not have one? 

I don't know whether it has one or not, but what happened to your engine that leads you to ask this question?  I assume something happened that made you think it doesn't and that it should.

[Wizard_03]

14 minutes ago, Stackup said:

I don't know whether it has one or not, but what happened to your engine that leads you to ask this question?  I assume something happened that made you think it doesn't and that it should.

Overboost 

 

Mechanically it doesn't make sense for it not to have one. That would be pretty irresponsible for high altitude fighter with multiple forms of forced induction, Water/meth injection, and an enormous engine. You'd think adequate boost control would be important. Especially since every other contemporary fighter has one. Its a big disadvantage since you can't just firewall the throttle in DCS P47 because it will let you overboost. So in a dogfight I have to manage the fight and constantly check my MP to make sure I'm not blowing myself up it's dumb.

Edited October 10, 2023 by Wizard_03

[grafspee]

22 minutes ago, Wizard_03 said:

Overboost 

 

Mechanically it doesn't make sense for it not to have one. That would be pretty irresponsible for high altitude fighter with multiple forms of forced induction, Water/meth injection, and an enormous engine. You'd think adequate boost control would be important. Especially since every other contemporary fighter has one. Its a big disadvantage since you can't just firewall the throttle in DCS P47 because it will let you overboost. So in a dogfight I have to manage the fight and constantly check my MP to make sure I'm not blowing myself up it's dumb.

 

Proper automatic boost control showed in P-47N but in early version you have only boost control for turbo supercharger but this unit governs exhaust back pressure.(constant back pressure does not provide constant boost and does not provide max permissible boost govern) 

P-47D is missing not only automatic boost control but engine cooling/ oil and intercooling shutters are operated manually, it is obvious that designers haven't focused on automation but on solving turbo supercharging single engine fighter.

There was many attempts to create turbo supercharging fighter but only republic P-47 succeed.

Edited October 10, 2023 by grafspee

[Stackup]

15 minutes ago, Wizard_03 said:

Mechanically it doesn't make sense for it not to have one. That would be pretty irresponsible for high altitude fighter with multiple forms of forced induction, Water/meth injection, and an enormous engine. You'd think adequate boost control would be important. Especially since every other contemporary fighter has one. Its a big disadvantage since you can't just firewall the throttle in DCS P47 because it will let you overboost. So in a dogfight I have to manage the fight and constantly check my MP to make sure I'm not blowing myself up it's dumb.

No it doesn't really make sense for it not to have one.  However, of course firewalling the throttle will cause an instantaneous overboost, relief valves have a finite opening through which pressure can escape and therefor if enough boost is applied too quickly the system will need time to catch up.  If overboosting does not occur with smooth application of the throttle, then it proves the system works.

I will say that expecting to be able to just throw the throttle around on a 2800 horsepower radial engine is stupid.  You really expect to not have to perform proper engine management throughout all regimes of flight?  In a 1940's airplane?  This isn't an F-16.  In the Mustang for example, you must keep track of your engine/oil temperature, especially during a dogfight since you can get slow with high power resulting in increased oil temperature due to decreased airflow over the oil cooler.  These planes will not manage or fly themselves for you...

[Wizard_03]

22 minutes ago, Stackup said:

No it doesn't really make sense for it not to have one.  However, of course firewalling the throttle will cause an instantaneous overboost, relief valves have a finite opening through which pressure can escape and therefor if enough boost is applied too quickly the system will need time to catch up.  If overboosting does not occur with smooth application of the throttle, then it proves the system works.

I will say that expecting to be able to just throw the throttle around on a 2800 horsepower radial engine is stupid.  You really expect to not have to perform proper engine management throughout all regimes of flight?  In a 1940's airplane?  This isn't an F-16.  In the Mustang for example, you must keep track of your engine/oil temperature, especially during a dogfight since you can get slow with high power resulting in increased oil temperature due to decreased airflow over the oil cooler.  These planes will not manage or fly themselves for you...

I can throw the throttle all the way forward in every other fighter without having to worry about it self destructing. Obviously neglect and abuse can cause you to exceed other limits. But your telling me that I can't put the throttle all the way forward without exceeding limits at a given altitude? I'm not talking about instantaneous overboost I'm talking about putting (as gently as you want) the throttle to the stop and the engine exceeding it's rated limits. 

 

That doesn't sound right at all. Imagine a race car where you can't step all the way on the gas without overboosting. Instead you can only step on it 95 percent of the way to get full rated safe power. If that were the case You'd be blowing engines left and right. Not to mention losing 

 

They absolutely had manifold pressure regulators in 1940s and they used them for the same reason the prop lever doesn't let you exceed the engines RPM limit (outside of a dive in case it needs to be said) 

Edited October 10, 2023 by Wizard_03

[grafspee]

8 minutes ago, Wizard_03 said:

The absolutely had manifold pressure regulators in 1940s 

For supercharged engines they did, but for turbo supercharged they did not.

Edited October 10, 2023 by grafspee

[Wizard_03]

Just now, grafspee said:

For supercharged engines they did, but for turbo supercharging they did not.

The P38s is 100 percent automatic. And has both as well. P38 doesn't even a separate boost lever. It's just a throttle. 

 

It also doesn't matter what is creating the charge, the regulator is in the manifold after all the compressor(s). A supercharged engine without a manifold pressure regulator would have the same issue. 

[Stackup]

18 minutes ago, Wizard_03 said:

the engine exceeding it's rated limits

What altitude, max manifold pressure achieved, Turbo RPM, etc.?  Give me some numbers so I can see if my test results match what you see.

At 10,000', I went full throttle, boost, and prop and acheived 61" Hg and 12,500 turbo RPM at redline RPM without water injection.  With water injection, the engine did exceed 64" Hg acheiving 68.5" at 14,500 turbo RPM.

According to Chuck's Guide operation of the WEP system should be done as follows quote, "Water injection occurs when the engine is running in War Emergency Power (WEP) mode, which is activated by pressing the water injection button on the throttle and then throttling up to approximately 1/8 inch from the full forward throttle position (95%).  The pressure in the collector reaches then up to 64 inches of Hg, increasing power by 30%."

 

Edited October 10, 2023 by Stackup
Numbers

[Wizard_03]

24 minutes ago, Stackup said:

What altitude, max manifold pressure achieved, Turbo RPM, etc.?  Give me some numbers so I can see if my test results match what you see.

I'm not at home so I can't test anything for you right now, but I assure you the DCS P47 will allow you to exceed 64" under a wide range of conditions because it's modeled without a manifold pressure regulator. 

 

Quick and dirty get above 15K arm water injection, put the prop, throttle and boost either connected or disconnected all the way forward and fly around. You'll exceed 64 very quickly and if your not checking the MP and manually retarding throttle/boost back to 64 your bearings will go within two minutes. Because of detonation Well before the engine oil, carb air or cylinder head temp overheats, well before you run out of water, ect. 

 

If the engine was equiped with a pressure regulator exceeding 64" should be very difficult or impossible under most conditions 

 

Edited October 10, 2023 by Wizard_03

[Stackup]

20 minutes ago, Wizard_03 said:

I'm not at home so I can't test anything for you right now, but I assure you the DCS P47 will allow you to exceed 64" under a wide range of conditions because it's modeled without a manifold pressure regulator. 

I just updated my above post with my numbers.  To summarize, Chuck's Guide says under WEP, the throttle should not be advanced past 95% or 1/8" from full throttle.  Having just tested it at above 15,000' where you should be using this, that comes out about right.

So, having determined that the engine does exceed WEP limits if full throttle is applied from my test and your experience and engine power degradation begins within a couple of minutes, we can conclude there is not a manifold pressure regulator on the P-47 in DCS and you should operate the aircraft with that in mind.

However, you will have to provide proof this is inaccurate and you have not so far besides talking about other aircraft with different engines and systems.  The Allison V-1710 used in the P-38 is not the same as the R-2800 used in the P-47 and you shouldn't expect them to have all the same systems simply because they were available at the time.

Edited October 11, 2023 by Stackup

[Wizard_03]

25 minutes ago, Stackup said:

I just updated my above post with my numbers.  To summarize, Chuck's Guide says under WEP, the throttle should not be advanced past 95% or 1/8" from full throttle.  Having just tested it at above 15,000' where you should be using this, that comes out about right.

So, having determined that the engine does exceed WEP limits if full throttle is applied from my test and your experience and engine power degradation begins within a couple of minutes, we can conclude there is not a manifold pressure regulator on the P-47 in DCS and you should operate the aircraft with that in mind.

However, you will have to provide proof this is inaccurate and you have not so far besides talking about other aircraft with different engines and systems.  The Allison V-1710 used in the P-38 is not the same as the R-2800 used in the P-47 and you shouldn't expect them to have all the same systems simply because they were available at the time.

All the German planes have regulators as well and every other sim I've played including the other three letter one with two P47s and they certainly have them. 

 

I can't prove a negative. Should I provide a source to show the engine has spark plugs too? ED should provide the source that shows the R2800 in 47D-30 did NOT have a manifold pressure regulator. Because I've never read or heard anything about the aircraft that even suggests it didn't, and for good reason because it makes absolutely no sense. 

 

I could maybe understand an aircraft set up for 150 octane fuel with its regulator dialed up to run 70" running lower grade fuel and you being able to go above limits but that's a very specific situation and the aircraft still has a regulator it's just tuned wrong. 

 

Not having one is so dangerous it's silly. We would have a laundry list of sources backing that up if that were the case. It would be all over the pilot manuals telling pilots be extremely careful not to overboost during BFM because the engine not protected from detonation at WEP Rather most sources suggest R2800 is actually a very tough engine and could take lots of abuse, and keep running even after sustaining battle damage. 

Edited October 11, 2023 by Wizard_03

[Stackup]

4 minutes ago, Wizard_03 said:

All the German planes have regulators

This isn't a German plane.

4 minutes ago, Wizard_03 said:

every other sim I've played including the other three letter one with two P47s and they certainly have them

Fair, but how do we know THEY had it modelled correctly?

5 minutes ago, Wizard_03 said:

Should I provide a source to show the engine has spark plugs too?

This is a reciprocating engine, spark plugs are necessary for operation.  A manifold pressure relief valve, while helpful, is most certainly not a necessary item for the proper operation of an engine when the pilot operates it within limits.  That's why they provide pilots with operating limitations...

6 minutes ago, Wizard_03 said:

ED should provide the source that shows the R2800 in 47D-30 did NOT have a manifold pressure regulator. Because I've never read or heard anything about the aircraft that even suggests it didn't, and for good reason because it makes absolutely no sense.

Just because you've never read something that says it didn't have one doesn't then mean that it did. 

If you're really that bent out of shape about it and can't bring yourself to pay attention to the engine to ensure that you, the pilot, are keeping it within limitations as is your job as pilot, then please submit a report in the bugs and problems section so ED is more likely to see it and tell you what their information is and whether this is correctly modeled.  Good luck with that though as they recently locked a similar thread about bearing limitations despite being given evidence from the actual aircraft manual that contradicted what they said and how they have it modeled.

[Wizard_03]

10 minutes ago, Stackup said:

This isn't a German plane.

Fair, but how do we know THEY had it modelled correctly?

This is a reciprocating engine, spark plugs are necessary for operation.  A manifold pressure relief valve, while helpful, is most certainly not a necessary item for the proper operation of an engine when the pilot operates it within limits.  That's why they provide pilots with operating limitations...

Just because you've never read something that says it didn't have one doesn't then mean that it did. 

If you're really that bent out of shape about it and can't bring yourself to pay attention to the engine to ensure that you, the pilot, are keeping it within limitations as is your job as pilot, then please submit a report in the bugs and problems section so ED is more likely to see it and tell you what their information is and whether this is correctly modeled.  Good luck with that though as they recently locked a similar thread about bearing limitations despite being given evidence from the actual aircraft manual that contradicted what they said and how they have it modeled.

Paying attention to the engine is not the issue. What happens when you push the throttle forward is. The burden of proof is on them, because  even their own manual makes no mention of this phenomenon.

 

Anyone can simply pull power to "fly with in the limits" in game that's not the issue, the issue is their model of the R2800 I shouldn't be required to use 95 percent throttle for max safe power. That's not listed in their manual or pilot manuals of the period. 

 

Short of a providing a blue print of the motor and giving a lecture on forced induction applications. I'm not sure what you want from me. I simply asked a question that no one has yet given me an answer too.

Edited October 11, 2023 by Wizard_03

[Stackup]

6 minutes ago, Wizard_03 said:

Paying attention to the engine is not the issue. What happens when you push the throttle forward is. The burden of proof is on them, because  even their own manual makes no mention of this phenomenon.

 

Anyone can simply pull power to "fly with in the limits" in game that's not the issue, the issue is their model of the R2800 I shouldn't be required to use 95 percent throttle for max safe power. That's not listed in their manual or pilot manuals of the period. 

 

Short of a providing a blue print of the motor and giving a lecture on forced induction applications. I'm not sure what you want from me. I simply asked a question that no one has yet given me an answer too.

Submit a bug report then.

[grafspee]

 

@Wizard_03 So what max boost should be governed by this boost regulator ? 52" or 64" ?

This is form P-47N manual and starting with P-47N-25 automatic engine control showed up but this one only control throttle valve and turbo waste gate to operate in best efficiency but still over boost could happen if you push throttle too far.

P-38 was plane from different company as well any other so this is no near proof that P-47 had ever automatic boost control.

P-47 D manual.

This should answer your question, P-47 did not have boost control like in P-51 or spitfire, if you pushed throttle and boost too far you will over boost.

So this mean that all other sims failed to deliver proper engine model

That is why i always choose DCS.

 

Edited October 11, 2023 by grafspee

[Art-J]

6 hours ago, Wizard_03 said:

I'm not at home so I can't test anything for you right now, but I assure you the DCS P47 will allow you to exceed 64" under a wide range of conditions because it's modeled without a manifold pressure regulator. 

Quick and dirty get above 15K arm water injection, put the prop, throttle and boost either connected or disconnected all the way forward and fly around. You'll exceed 64 very quickly and if your not checking the MP and manually retarding throttle/boost back to 64 your bearings will go within two minutes. Because of detonation Well before the engine oil, carb air or cylinder head temp overheats, well before you run out of water, ect. 

Just for the record, the engine dies quickly only if we can't keep the oil and carb temp within limits (head temps never go above redline anyway, so forget about them), and that will depend on ambient conditions and cooler settings.

From my limited airspeed- and torture-testing at sea level, overboost between 70 and 75+ (after a a shallow dive) at 2550 RPM can be kept continuously for as long as there's water in the tank, so about 30 minutes. For example, in ISA conditions, I can safely maintain 69.5" in level flight even with both oil and intercooler only half open. Gives about 25 kph IAS extra bonus compared to 64".

Granted, at summer hot ambient conditions and when boosting after a power climb with oil hot already, yes, it's indeed easy to go over the oil and carb temps redline and both coolers will have to be opened accordingly. Sometimes full open will not suffice and throttling down will be needed.

By the way, both full open cause about 12-13 kph IAS penalty compared to both half-open (again, at sea level at ISA conditions)

To sum it up, I don't know for certain if our -47 should have a regulator or not, but we don't really need to be THAT worried about overboost, 'cause as long as both temps are kept in check, the engine in DCS can take quite a lot of it (unlike also non-regulated P-40E in the "other sim").

[Wizard_03]

10 hours ago, grafspee said:

 

@Wizard_03 So what max boost should be governed by this boost regulator ? 52" or 64" ?

This is form P-47N manual and starting with P-47N-25 automatic engine control showed up but this one only control throttle valve and turbo waste gate to operate in best efficiency but still over boost could happen if you push throttle too far.

P-38 was plane from different company as well any other so this is no near proof that P-47 had ever automatic boost control.

P-47 D manual.

This should answer your question, P-47 did not have boost control like in P-51 or spitfire, if you pushed throttle and boost too far you will over boost.

So this mean that all other sims failed to deliver proper engine model

That is why i always choose DCS.

 

 

Both, a regulator can map for both water injection on and off. 

 

The first part is referring to the P47N loosing it's boost lever which is not what we are talking about.

 

The second part is also Hardly conclusive, you can still overboost in both the spit and the mustang too and they have regulators as well. That quip in the manual is referring to the take off stop which is not modeled in DCS. You also have full military power all the way up to 33k in DCS so that manual is at odds with what we have in the sim anyways. Unless it's referencing military power and not WEP which is what matters for this discussion. 

Edited October 11, 2023 by Wizard_03

[Wizard_03]

8 hours ago, Art-J said:

To sum it up, I don't know for certain if our -47 should have a regulator or not, but we don't really need to be THAT worried about overboost, 'cause as long as both temps are kept in check, the engine in DCS can take quite a lot of it (unlike also non-regulated P-40E in the "other sim").

We need to find out if the real one did, because I see having to manage the throttle to stay below max allowed manifold pressure and or opening up intercoolers and oil flaps in the middle of a dogfight as a huge disadvantage. And nowhere in pilot testimony or the manuals suggest it had that limitation. Other sims dont model it that way and there's no information in the DCS manual about it at all. 

 

If it is true then they need to place that in bold all over the operations section. Because it's a big deal and It means you have to be much more careful in the P47 with managing power then you probably think, certainly much more careful then all the other aircraft in DCS. In the P40 in the other sim, its annoying but your not really going up super high and certainly not fighting up high so its not a huge deal because you don't in fact over boost that much since as you get higher your engine runs out of breath anyways just need to watch out when diving quickly, not having a regulator in an aircraft designed expressly for high altitude fighting seems like a really big oversight. Especially since the pilot absolutely needs one to breath out of in any case, but they evidently forgot to put one on the engine? I don't buy it.

Edited October 11, 2023 by Wizard_03

[Brigg]

https://imgur.com/a/tcCeaRH

https://imgur.com/a/R0zlWya

https://imgur.com/a/UEh5AEK

 

Edited October 11, 2023 by Brigg

[Wizard_03]

26 minutes ago, Brigg said:

https://imgur.com/a/tcCeaRH

https://imgur.com/a/R0zlWya

 

Thank you so much, so according to this parts catalog as far back as the P47C they were equipped with manifold pressure regulators. Now the question is why does the DCS Version not have one, as earlier versions could and did use manifold Pressure regulators to control boost.

 

Can't really get more conclusive then that, literally written in black and white. I will submit a bug report.

[Brigg]

Yeah looks like the were added from the C-1. When they went from the -21 of the B to the -59 for the C-1 it was fitted with a A-17 turbosupercharger regulator

Edited October 11, 2023 by Brigg

[Wizard_03]

It only makes sense, with that much boost, and the inclusion of water injection with 47C they need to protect the engine from detonation especially during combat.

Bug report

 

Edited October 11, 2023 by Wizard_03