P-47: bad at boom and zoom?

[CountZero]

18 minutes ago, Legioneod said:

Other models or prop doesn't matter (for the most part) because the power available remains the same. The D-22 through the D-30 used the same engine and turbo setup so power available at certain altitudes remained constant, they didn't change just because a different prop was used.

 

Here's a D-26 vs D-28 for comparison. They both are bubbletops with the same engine/turbo and prop configuration. Only reason CA are different is because the D-26 is using 56" and the D-28 is using 64". The D-28 could still achieve 56" at 29000' even though it's top power critical altitude was far lower (24500' at 64")

in game i see 264mph with auto max setings gauges show 54" 2700rpm at 29000ft, so thats 424mph using this ( https://aerotoolbox.com/airspeed-conversions/ placing ias from game in Equivalent Airspeed: ), so how can you expect in game P-47 to be modeled to have 437mph at 24500 and then same speed also at 29000ft, its two differant airplanes, i dont understand how P-47 we have in game should have thouse two speeds same, at that two differant alts.

Edited June 9, 2020 by CountZero

[Legioneod]

13 minutes ago, CountZero said:

in game i see 264mph with max setings it shows 54" 2700rpm at 29000ft, so thats 424mph, so how can you expect in game P-47 to be modeled to have 437mph at 24500 and then same speed also at 29000ft, its two differant airplanes, i dont understand how P-47 we have in game should have thouse two speeds same at that 2 differant alts.

 

What you're not understanding is that the top speed for 56" (about 2300HP) at 29,000ft is 436 mph for the D-26. The top speed for 64" (about 2,600 HP) at 24,500ft is 437mph. So the power needed for 436mph at 29,000ft is less than the power needed at 24,000ft.

 

When the P-47 got higher boost settings it dropped the critical altitude because the Turbo couldn't maintain those higher boost pressures up to the previous critical altitude, so what ends up happening is the new critical altitude is for max power which would be 64" 24,500ft but the old settings are still possible at the old critical altitude. (56" at 29,000ft)

This is why you see the same/similar speeds at two different power settings and altitudes. Thats part of the benefit of having a turbo supercharger.

 

Basically the top speed for the P-47 plateaus for a bit when it hits its top power critical altitude.

Edited June 9, 2020 by Legioneod

[CountZero]

5 minutes ago, Legioneod said:

 

What you're not understanding is that the top speed for 56" (about 2300HP) at 29,000ft is 436 mph for the D-26. The top speed for 64" (about 2,600 HP) at 24,500ft is 437mph. So the power needed for 436mph at 29,000ft is less than the power needed at 24,000ft.

 

When the P-47 got higher boost settings it dropped the critical altitude because the Turbo couldn't maintain those higher boost pressures up to the previous critical altitude, so what ends up happening is the new critical altitude is for max power which would be 64" 24,500ft but the old settings are still possible at the old critical altitude. (56" at 29,000ft)

This is why you see the same/similar speeds at two different power settings and altitudes. Thats part of the benefit of having a turbo supercharger.

 

Basically the top speed for the P-47 plateaus for a bit when it hits its top power critical altitude.

So why is there not chart of P-47s showing their speeds like this:

 

Every single one sows it only with one peak, while other airplanes with sups show two stage peaks clearly. I dont understand why P-47D-28 we have in game should be modeled by P-47D-26 high alts but on low-mid alts by P-47D-28 data, and there should then be data for P-47D28 with him being able to do 436mph at 29000ft, stating it has two critical alts if this worked that way.

[Raven109]

46 minutes ago, Legioneod said:

 

What you're not understanding is that the top speed for 56" (about 2300HP) at 29,000ft is 436 mph for the D-26. The top speed for 64" (about 2,600 HP) at 24,500ft is 437mph. So the power needed for 436mph at 29,000ft is less than the power needed at 24,000ft.

 

When the P-47 got higher boost settings it dropped the critical altitude because the Turbo couldn't maintain those higher boost pressures up to the previous critical altitude, so what ends up happening is the new critical altitude is for max power which would be 64" 24,500ft but the old settings are still possible at the old critical altitude. (56" at 29,000ft)

This is why you see the same/similar speeds at two different power settings and altitudes. Thats part of the benefit of having a turbo supercharger.

 

That doesn't make sense in this case. According to your previous post, max speed for D-28 is reached at 24500ft. And now it's been discovered that the D-28 should be corrected to ~437mph @29500 ft. 

 

According to this diagram:

 

 

The 65" Hg D-42 is doing 437mph @24500ft and ~417mph @ 29500ft. As you see it can't have the same speed at high alt as it has at FTH of 24500ft, since this is the max, and all the other speeds must be smaller.

 

Why can't the D-42 hold the same constant (more or less) speed as the D-28? (if we assume, as you noted that the 28 can maintain boost pressure such that the speed only drops by a little higher up)

Edited June 9, 2020 by Raven109

[CountZero]

On that picture for yellow/red 65" line shows most closly what we have in game. Chart shows around 424mph that you get in game at 29000ft.

Edited June 9, 2020 by CountZero

[Raven109]

26 minutes ago, CountZero said:

On that picture for yellow/red 65" line shows most closly what we have in game.

 

Yes, that's why I chose it.

1 hour ago, ICDP said:

 

Agreed, we should not have to use gaming trick to get better performance.

 

I tried a few different IAS to TAS converters and some give very different results.  I then read that standard altimeter setting should be 29.92 and once I changed to that from a default of 28.16, the TAS result changed from 434 to 417 (temp set was -45c).

 

So TAS for the different aircraft at 29,522ft is.

 

Fw190D9: 405 mph TAS

Bf109K4 (both versions) 425 mph TAS

Bf109G14: 394 mph TAS

P51D stock: 426 mph TAS

P51D 150 octane: 443 mph TAS

P47D: 417 mph TAS

 

So yeah, it is underperforming at this altitude by ~ 15-20 mph.  I will do some further testing at various altitudes and compare to RL data.  When I compile that I will make a report on the beta tester forum.  Though I can't promise anything will be fixed at least I can bring this to the devs attention in a more direct fashion.

 

 

 

Thanks for taking the time to test. Just curious, which performance chart lists the speed for the 65"Hg 47D28 as being 417mph + 15-20mph @ 29500ft?

Edited June 9, 2020 by Raven109

[CountZero]

And from what i see that should be d-22 model by serial numbers 42-25539 - 26388  Republic P-47D-22-RE Thunderbolt , so thats what we should expect from BoN P-47 then ? same similar speeds as one we have now. 

[Legioneod]

37 minutes ago, CountZero said:

So why is there not chart of P-47s showing their speeds like this:

 

Every single one sows it only with one peak, while other airplanes with sups show two stage peaks clearly. I dont understand why P-47D-28 we have in game should be modeled by P-47D-26 high alts but on low-mid alts by P-47D-28 data, and there should then be data for P-47D28 with him being able to do 436mph at 29000ft, stating it has two critical alts if this worked that way.

 

35 minutes ago, Raven109 said:

 

That doesn't make sense in this case. According to your previous post, max speed for D-28 is reached at 24500ft. And now it's been discovered that the D-28 should be corrected to ~433mph @29500 ft. 

 

According to this diagram:

 

 

The 65" Hg D-42 is doing 437mph @24500ft and ~417mph @ 29500ft. As you see it can't have the same speed at high alt as it has at FTH of 24500ft, since this is the max, and all the other speeds must be smaller.

 

Why can't the D-42 hold the same constant (more or less) speed as the D-28? (if we assume, as you noted that the 28 can maintain boost pressure such that the speed only drops by a little higher up)

 

What you both fail to realize is that the test don't use 56" WEP at 29,000ft but use 56" dry instead. This is why those charts don't show the P-47 going 430+ at 29,000ft because they didnt use 56" WEP. The D-26 I listed earlier was using 56" with water injection. The chart above is without water injection.

31 minutes ago, Raven109 said:

 

Yes, that's why I chose it.

 

Thanks for taking the time to test. Just curious, which performance chart lists the speed for the 65"Hg 47D28 as being 417mph + 15-20mph @ 29500ft?

D-28 can't achieve 64" at 29,000ft only 56" is possible at that altitude. With WEP and 56" we should see a top speed of around 435mph at 29,000ft. Without WEP it will be lower.

[CountZero]

10 minutes ago, Legioneod said:

 

 

What you both fail to realize is that the test don't use 56" WEP at 29,000ft but use 56" dry instead. This is why those charts don't show the P-47 going 430+ at 29,000ft because they didnt use 56" WEP. The D-26 I listed earlier was using 56" with water injection. The chart above is without water injection.

But even if they used water, there would not be 2 peaks, whole line would be just moved to right, not added 2nd peaks, it top speed would just be shifted, not 2nd peak created.

If it works like you say and our game P-47 max speed should be 437 at around what we have now and then again 436 at 29000ft, that would look like nothing shown on any performance picture of P-47s, if things worked like that then they would show P-47s performances graphs like any other graphs of airplanes with some high alt boosts or supercharger shifts and so on... something that looks like that black lines i added to pcture. If that was normal for P-47 why there is no performance chart showing that like you see on other airplanes charts when sup is switched or some high alt boost added.

Edited June 9, 2020 by CountZero

[Legioneod]

12 minutes ago, CountZero said:

But even if they used water, there would not be 2 peaks, whole line would be just moved to right, not added 2nd peaks, it top speed would just be shifted, not 2nd peak created.

If it works like you say and our game P-47 max speed should be 437 at around what we have now and then again 436 at 29000ft, that would look like nothing shown on any performance picture of P-47s, if things worked like that then they would show P-47s performances graphs like any other graphs of airplanes with some high alt boosts or supercharger shifts and so on... 

They never used WI at 29,000ft when testing at 64" this is why no charts show it. I'm telling you at 56" WI at 29,000ft the P-47 will achieve a top speed of around 435mph.

You are correct though, there wouldn't be two peaks like you say at least not like you see with the P-51 or similar. It would just plateau and would be a steady line up to 29,000ft.

 

Tell me this. If a P-47 achieves 435 mph at 29,000ft with 56" and water injection but later gets upgrading to a higher boost and can achieve 435mph at 24,000ft with 64" and water injection. Whats reason would the P-47 not be able to achieve it's previous speed of 435 at 29,000ft? The only thing that changed is the boost so why can't it achieve it's previous speed?

 

In reality it could but I'm just asking you why you think it couldnt.

 

Notice the power at altitude and what setting use WI. (only 65 and 70 use water injection)

Notice that 56" is still available at 29,000ft but they just never tested it with water at that altitude (in this test), it says in the chart that it didnt use WI.

 

 

Edited June 9, 2020 by Legioneod

[Raven109]

28 minutes ago, Legioneod said:

 

 

What you both fail to realize is that the test don't use 56" WEP at 29,000ft but use 56" dry instead. This is why those charts don't show the P-47 going 430+ at 29,000ft because they didnt use 56" WEP. The D-26 I listed earlier was using 56" with water injection. The chart above is without water injection.

D-28 can't achieve 64" at 29,000ft only 56" is possible at that altitude. With WEP and 56" we should see a top speed of around 435mph at 29,000ft. Without WEP it will be lower.

 

At 29500ft, you can't have WEP, because the turbo can't hold 65"Hg MAP. All water does at 29500' is increase from 52" to 56" (ingame to 53-54"), forcing the turbo to operate into the over-speed area. But that doesn't mean that the 28 should have the same speed at 29500ft as it has at FTH (at 65"Hg). 

 

Water injection and the turbo start losing effectiveness over FTH.

The graphs you've posted indicate that you could jump (somehow, perhaps with water) from the 56" boost to the 58"?, but you only get 420mph at 29500ft.

Edited June 9, 2020 by Raven109

[CountZero]

9 minutes ago, Legioneod said:

They never used WI at 29,000ft when testing at 64" this is why no charts show it. I'm telling you at 56" WI at 29,000ft the P-47 will achieve a top speed of around 435mph.

You are correct though, there wouldn't be two peaks like you say at least not like you see with the P-51 or similar. It would just plateau and would be a steady line up to 29,000ft.

 

Tell me this. If a P-47 achieves 435 mph at 29,000ft with 56" and water injection but later gets upgrading to a higher boost and can achieve 435mph at 24,000ft with 64" and water injection. Whats reason would the P-47 not be able to achieve it's previous speed of 435 at 29,000ft? The only thing that changed is the boost so why can't it achieve it's previous speed?

 

In reality it could but I'm just asking you why you think it couldnt.

 

Notice the power at altitude and what setting use WI. (only 65 and 70 use water injection)

Notice that 56" is still available at 29,000ft but they just never tested it with water at that altitude (in this test), it says in the chart that it didnt use WI.

 

 

 " The airplane and engine handled well at all altitudes at the higher powers. At 70.0" Hg., water injection, a maximum speed of 444 MPH was obtained at 23,200 feet. At 65.0" Hg., with water a high speed of 439 MPH at 25,200 feet and a maximum rate of climb of 3260 ft/min. at 10,000 feet were obtained. At 65.0" Hg., without water a high speed of 430 MPH at 25,400 feet and a maximum rate of climb of 2850 ft/min. at 12,000 feet were obtained. At 56.0" Hg. without water a high speed of 418 MPH at 29,600 feet and a maximum rate of climb of 2330 ft/min. at 12,000 feet were obtained. At 52.0" Hg. without water a high speed of 412 MPH at 31,400 feet and a maximum rate of climb of 2030 ft/min. at 12,000 feet were obtained."

 

I look it up and see this is what that report say, so with no water it does 430 and with water 439 at almost same alt. Why they didnt run with water and without water test on higher alts then critical, maybe there is no benefit from it in configuration they run as its in game and some other airplanes that have emergancy boosts it peaks and then its no use.

[Legioneod]

1 minute ago, Raven109 said:

 

At 29500ft, you can't have WEP, because the turbo can't hold 65"Hg MAP. All water does at 29500' is increase from 52" to 56" (ingame to 53-54"), forcing the turbo to operate into the over-speed area. But that doesn't mean that the 28 should have the same speed at 29500ft as it has at FTH (at 65"Hg). 

 

Water injection and the turbo start losing effectiveness over FTH.

Here's a D-30 using 64" WEP, it's critical altitude FOR 64" IS 24,500FT but it can still achieve 56" WI at 29,000ft.

 

The top speed listed below is because it was using 56" WI at 29,000ft. higher speed is due to it being a bit lighter than the one above.

4 minutes ago, CountZero said:

 " The airplane and engine handled well at all altitudes at the higher powers. At 70.0" Hg., water injection, a maximum speed of 444 MPH was obtained at 23,200 feet. At 65.0" Hg., with water a high speed of 439 MPH at 25,200 feet and a maximum rate of climb of 3260 ft/min. at 10,000 feet were obtained. At 65.0" Hg., without water a high speed of 430 MPH at 25,400 feet and a maximum rate of climb of 2850 ft/min. at 12,000 feet were obtained. At 56.0" Hg. without water a high speed of 418 MPH at 29,600 feet and a maximum rate of climb of 2330 ft/min. at 12,000 feet were obtained. At 52.0" Hg. without water a high speed of 412 MPH at 31,400 feet and a maximum rate of climb of 2030 ft/min. at 12,000 feet were obtained."

 

I look it up and see this is what that report say, so with no water it does 430 and with water 439 at almost same alt. Why they didnt run with water and without water test on higher alts then critical, maybe there is no benefit from it in configuration they run as its in game and some other airplanes that have emergancy boosts it peaks and then its no use.

Like I said, 56" without water. With water it would be around 435mph give or take.

[Raven109]

6 minutes ago, Legioneod said:

Here's a D-30 using 64" WEP, it's critical altitude FOR 64" IS 24,500FT but it can still achieve 56" WI at 29,000ft.

 

The top speed listed below is because it was using 56" WI at 29,000ft. higher speed is due to it being a bit lighter than the one above.

 

Yes, I agree, but the D-42 can achieve, from the graphs you've posted,  ~423mph @ 29500ft, with 56"Hg + WI. WI doesn't add that much higher up, which is a bit different from ICDP's tests which concluded that the error is 15-20mph.

Edited June 9, 2020 by Raven109

[Legioneod]

2 minutes ago, Raven109 said:

 

Yes, I agree, but the D-42 can achieve, from the graphs you've posted,  ~423mph @ 29500ft, with 56"Hg + WI. WI doesn't add that much higher up.

It wasn't using water injection at 29,000ft. I've listed the chart from that test. 56" is without water in that test.

Heres the chart.

Clearly shows 56" without water.

Edited June 9, 2020 by Legioneod

[Raven109]

3 minutes ago, Legioneod said:

It wasn't using water injection at 29,000ft. I've listed the chart from that test. 56" is without water in that test.

 

Yes, I understand; what I mean is for you to look at the 65"Hg + H2O line @ 29500ft. The 65" degrade to a smaller MAP at 29500ft, because the turbo can't hold it anymore. You will see that the speed is ~423mph. You don't need to follow the 56" line.

 

 

Edited June 10, 2020 by Raven109

[CountZero]

2 minutes ago, Legioneod said:

Here's a D-30 using 64" WEP, it's critical altitude FOR 64" IS 24,500FT but it can still achieve 56" WI at 29,000ft.

 

The top speed listed below is because it was using 56" WI at 29,000ft. higher speed is due to it being a bit lighter than the one above.

Like I said, 56" without water. With water it would be around 435mph give or take.

If thats same P-47 and have 437 at 24500 and then again 443 at 29000, then in game P-47 dont behave like that, in game P-47 behaves like on charts. How would that P-47 chart even look, with 2 peaks or just almost strait line for ~5000ft, in game there is not big benefit from boost up high. Would they make that big error if it worked like that on real one.

[Legioneod]

7 minutes ago, Raven109 said:

 

Yes, I understand; what I mean is for you to look at the 65"Hg + H2O line @ 29500ft. The 65" degrade to a smaller MAP at 29500ft, because the turbo can't hold it anymore. You will see that the speed is ~423mph.

 

 

 

Yes the turbo can't hold 64" at 29,000ft but it can hold 56WI at 29,000ft. That's the point that you're not understanding.

 

This is with 56" Water Injection. It's the same turbo as used on the D-30 listed above with a critical altitude of 24,500ft. And the same turbo (I think) on the test above.

 

4 minutes ago, CountZero said:

If thats same P-47 and have 437 at 24500 and then again 443 at 29000, then in game P-47 dont behave like that, in game P-47 behaves like on charts. How would that P-47 chart even look, with 2 peaks or just almost strait line for ~5000ft, in game there is not big benefit from boost up high. Would they make that big error if it worked like that on real one.

It's the same P-47 block (D-30) they use the same turbo and engine combo, even if they are different aircraft it doesnt matter.

Pretty much just a straight line. They didnt model it because it's not shown on the charts, whats shown is 56" at 29,000ft without water injection.

In-game we can't even get 56" without water injection, only 52-53" which makes a difference. A few inches makes a big difference.

Edited June 10, 2020 by Legioneod

[Raven109]

5 minutes ago, Legioneod said:

 

Yes the turbo can't hold 64" at 29,000ft but it can hold 56WI at 29,000ft. That's the point that you're not understanding.

 

This is with 56" Water Injection. It's the same turbo as used on the D-30 listed above with a critical altitude of 24,500ft. And the same turbo (I think) on the test above.

 

I don't understand why you keep looking at the 56" line, when you already have a 65"+H2O line which reaches 29500ft. There you can see that the speed is 423mph. It's the graph you posted.

65"+H2O drops to a MAP at 29500ft which is greater than 56", you can see this on the graph.

 

Are you saying that the graph for the D42 @ 65"+H2O @ 29500ft is irrelevant for the D28?

Edited June 10, 2020 by Raven109

[CountZero]

1 minute ago, Legioneod said:

 

Pretty much just a straight line.

Up to what alt then, would it just look like this then:

[Legioneod]

Just now, CountZero said:

Up to what alt then, would it just look like this then:

Pretty much. As you can see with the D-30. It would start decreasing speed gradually as it got above 56' critical altitude.

[CountZero]

I didnt see in any game P-47 top speed behaving like that, it will be nice to try dcs one and see how its there when they are done with it.

Edited June 10, 2020 by CountZero

[Legioneod]

11 minutes ago, Raven109 said:

 

Yes, I understand; what I mean is for you to look at the 65"Hg + H2O line @ 29500ft. The 65" degrade to a smaller MAP at 29500ft, because the turbo can't hold it anymore. You will see that the speed is ~423mph. You don't need to follow the 56" line.

 

 

I mention it because a turbo that can achieve 430+ mph at 29,000ft with 56" WI won't magically stop being able to achieve that just because the boost is increased to 64" WI at 24,000ft.

The Turbo is still capable of its previous performance.

1 minute ago, CountZero said:

I didnt see in any game P-47 top speed behaving like that, it will be nice to try dcs one and see how its there when they are done with it.

Thats because no game notices this quirk. I've shown reports of a D-30 block that achieves similar speeds at two different altitudes. Imo thats proof enough.

[Raven109]

Just now, Legioneod said:

I mention it because a turbo that can achieve 430+ mph at 29,000ft with 56" WI won't magically stop being able to achieve that just because the boost is increased to 64" WI at 24,000ft.

The Turbo is still capable of its previous performance.

 

Ok, then something must be different for the D42, which I doubt. Since the D42 reaches the same FTH speed as the D28.

[Legioneod]

3 minutes ago, Raven109 said:

 

Ok, then something must be different for the D42, which I doubt. Since the D42 reaches the same FTH speed as the D28.

Only thing that's different is that the test didn't run 65" WI above it's critical altitude, if it did then it would decrease to 56" WI and would be similar speeds to the D-30 I listed above (which btw is using similar 64" as listed in the test above)

 

64" WEP at 24,000ft

 

56" WI 29,000ft slightly lighter weight.

Edited June 10, 2020 by Legioneod

[CountZero]

7 minutes ago, Legioneod said:

I mention it because a turbo that can achieve 430+ mph at 29,000ft with 56" WI won't magically stop being able to achieve that just because the boost is increased to 64" WI at 24,000ft.

The Turbo is still capable of its previous performance.

Thats because no game notices this quirk. I've shown reports of a D-30 block that achieves similar speeds at two different altitudes. Imo thats proof enough.

Do reports for it show speeds by differant alts in betwen also, its same P-47 with no changes, if yes to me thats also enought to change my mined and see that in game speeds abow 7000m are to slow then. I just dont understand why there is no performance chart showing that type of graph with P-47 using water at all alts, and not just ones like shown in graphs on net with one clear peak. Well atleast you changed my mined and someone in their FM team should check it out atleast, i was sure there is nothing to this and all was corect as shown on original pictures.

Edited June 10, 2020 by CountZero

[Legioneod]

5 minutes ago, CountZero said:

Do reports for it show speeds by differant alts in betwen also, its same P-47 with no changes, if yes to me thats also enought to change my mined and see that in game speeds abow 7000m are to slow then. I just dont understand why there is no performance chart showing that type of graph with P-47 using water at all alts, and not just ones like shown in graphs on net with one clear peak. Well atleast you changed my mined and someone in their FM team should check it out.

Honestly I don't know why, it doesn't make any sense to me either that they didn't test WI at all altitudes but the charts clearly show that they didn't.

Maybe I am wrong idk but it looks odd.

Edited June 10, 2020 by Legioneod

[CountZero]

I was looking more on that P-47 performance site and here it says P-47D-26 should be doing 423mph with water at 30000ft and if you look at speeds they rais normaly with alts:

[Legioneod]

9 minutes ago, CountZero said:

I was looking more on that P-47 performance site and here it says P-47D-26 should be doing 423mph with water at 30000ft and if you look at speeds they rais normaly with alts:

Thats at 14,500 lbs. The document I listed for the D-26 are the official numbers. The D-26 in the document I listed is 56" WI at 29,000ft with a weight of 12,961 lbs (basically 13,000lbs)

A 10+ mph  loss in speed doesn't sound too unlikely when hauling an extra 1500 lbs.

 

Also the D-26 in the chart above is using a WEP of 56" (2300hp) same as in the one I listed.

 

Speeds aren't that far off, probably just due to the extra weight.

Edited June 10, 2020 by Legioneod

[Raven109]

9 hours ago, Legioneod said:

Tell me this. If a P-47 achieves 435 mph at 29,000ft with 56" and water injection but later gets upgrading to a higher boost and can achieve 435mph at 24,000ft with 64" and water injection. Whats reason would the P-47 not be able to achieve it's previous speed of 435 at 29,000ft? The only thing that changed is the boost so why can't it achieve it's previous speed?

 

So, if we go and read the reports, we will see that the P-47 rated at 56"Hg was using another supercharger turbo regulator than the 64"Hg P-47 . The first uses the A-17 regulator to maintain 56" boost up to 33000ft (you can see this on the D-10 performance charts); this regulator cannot be used with 64"Hg boost. To get 64" Hg, for the R-2800-59, you need to use the A-13 or A-23 turbo supercharger regulators. This shows that the power systems are different between the 56" Hg and the 64" Hg planes.

 

 

Whole report here: http://www.wwiiaircraftperformance.org/p-47/P-47_Water-Injection_3feb44.pdf

 

We can also see that the 56" Hg for the D-10 was obtained by using water:

http://www.wwiiaircraftperformance.org/p-47/P-47D_43-75035_Eng-47-1652-A.pdf

 

The table in the last document indicates that the A-17 s/c turbo regulator has an influence on maximum boost altitude, as noted on the climb table.

 

These are two different engine setups and their performance must not be combined to obtain just one a/c.

 

Therefore, I think it's correct to assume that, since the D-28 has:

a. An R-2800-59 engine, and

b. 64"Hg boost with water injection

It's using an A-13/23 regulator and that it has a similar performance to the D-42 D-22 (42-26167), that means that the performance is the orange/red line which you can see here (the D-42 D-22 is 1"Hg over the D-28, so perhaps the D-28 will be a bit slower):

 

which, as tested by @ICDP, shows that it's what we have in-game.

Edited June 10, 2020 by Raven109
Corrected from D-42 to D-22, thanks Tbolt47

[ICDP]

Good find Raven.  It seems to explain the P47D in sim performance.

 

I did find this taken from AHT (great book if you can find it cheap).  If you are in the UK  this price from Amazon is a steal.

https://www.amazon.co.uk/AMERICAS-HUNDRED-THOUSAND-Production-Fighters/dp/0764300725

 

If you look at the P-47D-25 graph it does have a straight line for performance from just under 25,000ft - just under 30,000ft.  These are at combat power (WEP) according to the associated text.

 

Edited June 10, 2020 by ICDP

[ICDP]

I would also like to put some of the pilot descriptions of the P47 from AHT out here.  These are taken from the section on Aircraft Handling, manoeuvring sub section.

• The general verdict of pilots on P-47 manoeuvrability was "fair" to "poor".  Though one pilot said it had amazing high alt manoeuvrability.
• None of the pilots raved about aileron performance of the P-47s.
• The P47D ranked 5th for high speed ailerons among pilots of late war USAAF and USN fighters
• The P47 ranked 4th for dive capability among pilots of late war USAAF and USN fighter
• AHT also mentions aileron forces became high at speeds over 350 mph IAS

 

Now let's add the evidence from other actual first hand test/tactical trials.

• Roll tests and charts from the USAAF show the P47 had mediocre roll-rate at high speeds
• Roll tests and diagrams from RAF testing shows the P47 had mediocre roll-rate at high speeds
• Tactical trials of the P47D against an A6M5 show it to have some advantage in dive and zoom but nothing that can't easily be lost after doing a few aggressive manoeuvrers.
• Tactical trials of the P47D against an Fw190A show the Fw190 to have better acceleration at low - medium speeds.  From 250mph, Fw190A also had better initial dive acceleration and zoom climb.  Though the P-47D did catch up and overtake the Fw190 eventually.
• Pilots manual indicates that recovery from high speed dives requires use of trim

 

We have also had an article posted where a current warbird flyer states the P47D will bleed more speed during manoeuvrers than other WWII types.

I agree some of this is anecdotal but most of this evidence comes form wartime tests and tactical trials.  Taken together then all this evidence would suggest that the P-47 didn't excel at high speed manoeuvring as some people expected.  Yes it can dive and zoom well, but it's only advantage was over ~300mph, get below that and you have just lost your marginal advantage.  So if you are fighting Fw190s from 200 - 300 mph then the Fw190 will have an advantage in acceleration, dive and zooms and a big advantage in roll-rate.

 

I feel some people just need to review their expectations of what the P-47D could do.  It was poor to fair for manoeuvrability at pretty much all speeds until you got it up very high.  It also excelled at ground pounding because it was robust and carried a lot of ordnance.

Edited June 10, 2020 by ICDP

[Tbolt47]

1 hour ago, Raven109 said:

 

So, if we go and read the reports, we will see that the P-47 rated at 56"Hg was using another supercharger turbo regulator than the 64"Hg P-47 . The first uses the A-17 regulator to maintain 56" boost up to 33000ft (you can see this on the D-10 performance charts); this regulator cannot be used with 64"Hg boost. To get 64" Hg, for the R-2800-59, you need to use the A-13 or A-23 turbo supercharger regulators. This shows that the power systems are different between the 56" Hg and the 64" Hg planes.

 

 

Whole report here: http://www.wwiiaircraftperformance.org/p-47/P-47_Water-Injection_3feb44.pdf

 

We can also see that the 56" Hg for the D-10 was obtained by using water:

http://www.wwiiaircraftperformance.org/p-47/P-47D_43-75035_Eng-47-1652-A.pdf

 

The table in the last document indicates that the A-17 s/c turbo regulator has an influence on maximum boost altitude, as noted on the climb table.

 

These are two different engine setups and their performance must not be combined to obtain just one a/c.

 

Therefore, I think it's correct to assume that, since the D-28 has:

a. An R-2800-59 engine, and

b. 64"Hg boost with water injection

It's using an A-13/23 regulator and that it has a similar performance to the D-42, that means that the performance is the orange/red line which you can see here (the D-42 is 1"Hg over the D-28, so perhaps the D-28 will be a bit slower):

 

which, as tested by @ICDP, shows that it's what we have in-game.

 

So it's close to the orange/red line for speed, has anyone tested the climb performance, how does it compare to the test?

 

 

By the way it's a D-22 not D-42, you are reading the aircraft serial number.

[Raven109]

1 hour ago, ICDP said:

Good find Raven.  It seems to explain the P47D in sim performance.

 

I did find this taken from AHT (great book if you can find it cheap).  If you are in the UK  this price from Amazon is a steal.

https://www.amazon.co.uk/AMERICAS-HUNDRED-THOUSAND-Production-Fighters/dp/0764300725

 

If you look at the P-47D-26 graph it does have a straight line for performance from just under 25,000ft - just under 30,000ft.  These are at combat power (WEP) according to the associated text.

 

 

Well, I don't have an explanation for that chart.  All I have is this table from the pilots manual for the D-25. 

 

Spoiler

 

According to this, 64"Hg is available up to 26000ft. I can't see how an aircraft can maintain constant speed with altitude if its power is dropping.

 

What's bothering me about having constant speed with altitude is that no Republic chart shows that. I would assume that an engineer would like to highlight that performance benefit and add it to the original charts.

 

-------------------------------------

35 minutes ago, Tbolt47 said:

By the way it's a D-22 not D-42, you are reading the aircraft serial number.

 

You are right. Thanks for noticing that.

-------------------------------------

 

Regarding the chart from the book, please note that it shows around 425?mph constant, which is below the maximum speed for the 64" P-47 at 25000ft. But, this could indicate that it might have been obtained at a lower power setting. Which means that by increasing throttle as you go up you can hold the 425mph constant, due to still having some left-over power resource. Just a hypothesis, because I can't see any reason why someone would run such a test.

 

Edited June 10, 2020 by Raven109

[ICDP]

54 minutes ago, Raven109 said:

 

Well, I don't have an explanation for that chart.  All I have is this table from the pilots manual for the D-25. 

 

  Reveal hidden contents

 

According to this, 64"Hg is available up to 26000ft. I can't see how an aircraft can maintain constant speed with altitude if its power is dropping.

 

What's bothering me about having constant speed with altitude is that no Republic chart shows that. I would assume that an engineer would like to highlight that performance benefit and add it to the original charts.

 

-------------------------------------

 

You are right. Thanks for noticing that.

-------------------------------------

 

Regarding the chart from the book, please note that it shows around 423?mph constant, which is way below the maximum speed for the 64" P-47 at 25000ft. But, this could indicate that it might have been obtained with at a lower power setting. Which means that by increasing throttle as you go up you can hold the 423mph constant, due to still having some left-over power resource.

 

 

The power would be dropping but it could be dropping at a rate that means it is keeping similar performance at slightly lower air density?  So power loss and lower air density seem to be in perfect balance to keep same speed from ~24,000 to ~30,000ft,  Is that plausible?

Edited June 10, 2020 by ICDP

[Legioneod]

2 hours ago, ICDP said:

Good find Raven.  It seems to explain the P47D in sim performance.

 

I did find this taken from AHT (great book if you can find it cheap).  If you are in the UK  this price from Amazon is a steal.

https://www.amazon.co.uk/AMERICAS-HUNDRED-THOUSAND-Production-Fighters/dp/0764300725

 

If you look at the P-47D-26 graph it does have a straight line for performance from just under 25,000ft - just under 30,000ft.  These are at combat power (WEP) according to the associated text.

 

This is what I've been saying, the speed curve plateaus because the performance stays pretty constant due to having similar speeds at 64" critical altitude and 56" critical altitude. Thanks for posting this because it shows what I've been trying to say.

 

3 hours ago, Raven109 said:

 

So, if we go and read the reports, we will see that the P-47 rated at 56"Hg was using another supercharger turbo regulator than the 64"Hg P-47 . The first uses the A-17 regulator to maintain 56" boost up to 33000ft (you can see this on the D-10 performance charts); this regulator cannot be used with 64"Hg boost. To get 64" Hg, for the R-2800-59, you need to use the A-13 or A-23 turbo supercharger regulators. This shows that the power systems are different between the 56" Hg and the 64" Hg planes.

 

 

Whole report here: http://www.wwiiaircraftperformance.org/p-47/P-47_Water-Injection_3feb44.pdf

 

We can also see that the 56" Hg for the D-10 was obtained by using water:

http://www.wwiiaircraftperformance.org/p-47/P-47D_43-75035_Eng-47-1652-A.pdf

 

The table in the last document indicates that the A-17 s/c turbo regulator has an influence on maximum boost altitude, as noted on the climb table.

 

These are two different engine setups and their performance must not be combined to obtain just one a/c.

 

Therefore, I think it's correct to assume that, since the D-28 has:

a. An R-2800-59 engine, and

b. 64"Hg boost with water injection

It's using an A-13/23 regulator and that it has a similar performance to the D-42 D-22 (42-26167), that means that the performance is the orange/red line which you can see here (the D-42 D-22 is 1"Hg over the D-28, so perhaps the D-28 will be a bit slower):

 

which, as tested by @ICDP, shows that it's what we have in-game.

 

I've thought the same thing at first so I check with the model specifications and the D-22 through the D-30 all have the same engine, turbo, and turbo regulator.

ICDP posted a pic from AHT that shows the speed curve that we should see in-game. A straight line from 64" critical altitude to 56" critical altitude.

 

56" and 64" power settings both use the same turbo regulators.

 

 

I know it seems like I'm draggin this out but it's because i've checked it over and over. I've looked through all the different setups and power settings. We should be seeing a straight or nearly straight line from 64" to 56" critical altitude (24,000ft - 29,000ft)

 

1 hour ago, ICDP said:

 

The power would be dropping but it could be dropping at a rate that means it is keeping similar performance at slightly lower air density?  So power loss and lower air density seem to be in perfect balance to keep same speed from ~24,000 to ~30,000ft,  Is that plausible?

This is pretty much what happens imo, if you notice that to keep speed at 29,000ft requires less power than to keep it at 24,000ft. This is why we see a straight line in the speed curve.

The P-47 made enough power at 56" WI to keep a speed of 435+ mph so even when it upgraded to 64" could reach the same speed. 64" just made it so it could reach those speeds at a lower altitude, this is why we see a plateau. (straight line)

Edited June 10, 2020 by Legioneod

[ICDP]

7 minutes ago, Legioneod said:

This is what I've been saying, the power curve plateaus because the performance stays pretty constant due to having similar speeds at 64" critical altitude and 56" critical altitude. Thanks for posting this because it shows what I've been trying to say.

 

 

I've thought the same thing at first so I check with the model specifications and the D-22 through the D-30 all have the same engine, turbo, and turbo regulator.

ICDP posted a pic from AHT that shows the power curve that we should see in-game. A straight line from 64" critical altitude to 56" critical altitude.

 

56" and 64" power settings both use the same turbo regulators.

 

 

 

 

 

 

 

 

 

 

This is pretty much what happens imo, if you notice that to keep speed at 29,000ft requires less power than to keep it at 24,000ft. This is why we see a straight line in the speed curve.

The P-47 made enough power at 56" WI to keep a speed of 435+ mph so even when it upgraded to 64" could reach the same speed. 64" just made it so it could reach those speeds at a lower altitude, this is why we see a plateau. (straight line)

 

Just a minor clarification to ensure we identify the correct problem, that is not a power curve, but a speed curve.  Power is dropping but a rate that is in balance with the lower air density as altitude increases.  So the speed curve has an almost straight line from ~24,000ft to ~30,00ft.

[Legioneod]

1 minute ago, ICDP said:

 

Just a minor clarification to ensure we identify the correct problem, that is not a power curve, but a speed curve.  Power is dropping but a rate that is in balance with the lower air density as altitude increases.  So the speed curve has an almost straight line from ~24,000ft to ~30,00ft.

Yes speed curve is what I meant. Power drops from 2600hp to 2300hp at 29000ft. I've edited my above post.

Edited June 10, 2020 by Legioneod

[Raven109]

18 minutes ago, Legioneod said:

This is what I've been saying, the power curve plateaus because the performance stays pretty constant due to having similar speeds at 64" critical altitude and 56" critical altitude. Thanks for posting this because it shows what I've been trying to say.

 

 

I've thought the same thing at first so I check with the model specifications and the D-22 through the D-30 all have the same engine, turbo, and turbo regulator.

ICDP posted a pic from AHT that shows the power curve that we should see in-game. A straight line from 64" critical altitude to 56" critical altitude.

 

56" and 64" power settings both use the same turbo regulators.

 

 

 

 

 

 

 

 

 

 

I think you're confusing the plane that can only run up to 56" with the plane that can run both 56" and 64". The one that can run 64" cannot run 56" up to 31000ft. You can see this from the actual test data that you posted above.

 

So, D10 can hold 56" up to 31000ft.

D22 (and onwards) can hold 64" up to 26000ft. Because these aircraft don't have the A-17 regulator, they can't hold 56" up to 31000ft. If they had the A-17 regulator, they could hold 56" up to 31000ft, but they could not be boosted further than 56".

Even this last screenshot you posted confirms this:

D-10 up to D-16 (not including) use the A-17 reg. (cannot support 64" up to 26000ft, but can support 56" boost up to 31000ft)

D-16 up to D-22 (not including) use the A-13 reg. (can support 64" up to 26000ft, but cannot support 56" boost up to 31000ft)

D-22 and up (i.e D-28) use the A-23 reg. (can support 64" up to 26000ft, but cannot support 56" boost up to 31000ft)

 

If you believe that the D-25 chart from AHT is true, then you should cap the max speed of the aircraft to 425mph after 25000ft, although the 65" can reach up to 437mph accoring to the tests at 25000ft.

Edited June 10, 2020 by Raven109

[Legioneod]

9 minutes ago, Raven109 said:

I think you're confusing the plane that can only run up to 56" with the plane that can run both 56" and 64". The one that can run 64" cannot run 56" up to 31000ft. You can see this from the actual test data that you posted above.

 

So, D10 can hold 56" up to 31000ft.

D22 (and onwards) can hold 64" up to 26000ft. Because these aircraft don't have the A-17 regulator, they can't hold 56" up to 31000ft. If they had the A-17 regulator, they could hold 56" up to 31000ft, but they could not be boosted further than 56".

Even this last screenshot you posted confirms this:

D-10 up to D-16 use the A-17 reg. (cannot support 64" up to 26000ft, but can support 56" boost up to 31000ft)

D-16 up to D-22 use the A-13 reg. (can support 64" up to 26000ft, but cannot support 56" boost up to 31000ft)

D-22 and up (i.e D-28) use the A-23 reg. (can support 64" up to 26000ft, but cannot support 56" boost up to 31000ft)

 

If you believe that the D-25 chart from AHT is true, then you should cap the max speed to the aircraft to 425mph after 25000ft, although the 65" can reach up to 437mph accoring to the tests at 25000ft.

I'm not confusing things dude, I've checked this over and over again. The D-26 I listed above uses a power of 56" not 64" and an A-23 regulator.

You can keeps saying I'm wrong but the speed curve should be pretty much straight between 64" critical alt to 56" critical alt.

 

The reason the D-25 was slower in that chart is because it was 14,500 lbs. At lighter weights it is faster.

 

 

 

 

Here's a D-25 at around 13,000lbs. (not exact weight)

 

here's a D-27 after it was boosted to 64"

Edited June 10, 2020 by Legioneod