What's your top speed on P-47 at about 5000 ft?

[Swing 202]

6 hours ago, 7.GShAP/Silas said:

 

What's the best/simplest way to turn this into max continuous setting?

 

For me Max Continuous setting at 2000m, Auto level on :  Throttle 100%, Turbo 87%, 2550 RPM (89%), inlet cowl 50%, outlet cowl 0%, Oil Rad 0%, 47 inch/hg, 476 km/h. (mixture auto rich, i don't have make tests with Full rich).

Edited November 23, 2018 by Swing

[Rattlesnake 257]

3 hours ago, Ehret said:

 

I found a workaround! (kind of)

 

You can enable the water injection just on the nominal (47" @ 2530rpm) to get something like an "intermediate WEP" - rpm stays the same but MP rises to 59". Not only it's significantly stronger than the "normal" combat power at 55" @ 2700rpm but lasts as long. Even better, after that you can switch to "full" WEP for full 5m without a hitch.

 

I managed to climb to the 20k ft on the "boosted nominal" at initial rate around 3000ft/m then enabled full power; was running very fast at that alt for 5m and 45s before the engine finally seized.

 

[JtD 2454]

Quickly browsing through this topic, yet not the entire forum - so I might have missed something.

 

Why do the in game P-47 and the reference given by Gavrick use such a low full throttle altitude? In every official document I had seen so far, the rated altitude for 64" boost was given in the range of 26500' (8000m). Some considerably more.

 

Is the data from the model description, which I don't have, for lower turbo rpm than the 20-22k the model should have?

 

Also, why is 7000m the in game critical altitude when the (conservative) source already gives 24500' (7500m)?

[Legioneod 2021]

33 minutes ago, JtD said:

Quickly browsing through this topic, yet not the entire forum - so I might have missed something.

 

Why do the in game P-47 and the reference given by Gavrick use such a low full throttle altitude? In every official document I had seen so far, the rated altitude for 64" boost was given in the range of 26500' (8000m). Some considerably more.

 

Is the data from the model description, which I don't have, for lower turbo rpm than the 20-22k the model should have?

 

Also, why is 7000m the in game critical altitude when the (conservative) source already gives 24500' (7500m)?

 

I've been wondering the same thing as well. Only thing I can think of is the Turbo regulator but even then I'm not sure. D-28 and D-30 has same engine and regulator iirc and yet they have completely different critical altitudes it seems, not sure why.

 

Also find it odd that CA and top speed is lower in-game than in the document posted, doesn't make sense to me.

[JtD 2454]

Looking at testing it appears the difference between 20k and 22k turbo rpm is about 3000', about 1000m, about what I think is missing. Maybe Gavrick could clarify this, too?

[LeLv76_Erkki 186]

Water-injected 59", linked turbo and throttle, 2550 RPM at 3000 m: 320 mph indicated and "boosted mode timer" elapsed at 16 min 45 seconds. I think thats because the water ran out at that point.

 

Important notice: that is only around 10 mph indicated slower than 65" full throttle mode (5 minutes only), still faster than 65" at 2700 RPM and about 5 km/h faster than Bf 109 G-2 at that altitude. And about 15 km/h faster than 190 A-5 with closed gills that uses its own 30 min kampf mode.

 

I strongly recommend staying at 2550 RPM and avoiding going over 60" Hg mark except in emergency. That 15 + min of water can be used all in one go and not give up much performance.

[Sgt_Joch 284]

So is the fact that the bird has a higher top speed at 2550 rpm a reflection of the real life performance of that engine/prop combo or just another game code anomaly?

 

As I recall, you have the same thing with the Yak-1?

 

I have not read all the P47 tests in detail, but dont recall tests at 2550 rpm.

 

 

 

Edited November 24, 2018 by Sgt_Joch

[Cpt_Siddy 1413]

8 minutes ago, Sgt_Joch said:

 

As I recall, you have the same thing with the Yak-1?

 

 

 

 

 

IIRC Yak-1b had it and it was top speed on altitudes below 1km. 90% RPM had marginally larger top speed on the deck. 

 

Not sure of the other 2 models we have. 

[=362nd_FS=RoflSeal 596]

23 minutes ago, Sgt_Joch said:

So is the fact that the bird has a higher top speed at 2550 rpm a reflection of the real life performance of that engine/prop combo or just another game code anomaly?

 

As I recall, you have the same thing with the Yak-1?

 

I have not read all the P47 tests in detail, but dont recall tests at 2550 rpm.

 

 

 

I am pretty sure the reason for this is because the engine would encounter detonation having such high boost pressures at such low RPM and this is not modelled in the game.

Edited November 24, 2018 by RoflSeal

[Talon_ 1774]

My worry so far is that the Jug will give up after 5 minutes on water 64" followed by only 4 minutes on combat 52". It doesn't seem realistic that the DB605DC can make 2000hp for longer than the R-2800.

 

Testing here: https://streamable.com/6s2ah

Edited November 24, 2018 by Talon_

[CountZero 1965]

7 hours ago, JtD said:

Quickly browsing through this topic, yet not the entire forum - so I might have missed something.

 

Why do the in game P-47 and the reference given by Gavrick use such a low full throttle altitude? In every official document I had seen so far, the rated altitude for 64" boost was given in the range of 26500' (8000m). Some considerably more.

 

Is the data from the model description, which I don't have, for lower turbo rpm than the 20-22k the model should have?

 

Also, why is 7000m the in game critical altitude when the (conservative) source already gives 24500' (7500m)?

 

using the same settings as gavric say we should use, at 7000m (23000ft) i get IAS of 301mph, and if i use same iastas callculator as before i get thats 438mph tas. So thats faster then 292ias=433mph tas i get on 7500m ( 24500ft) from previous test posted before, so it seams its faster on 23000ft then 24500ft in my test atleast.

 

[Ehret 448]

5 minutes ago, Talon_ said:

My worry so far is that the Jug will give up after 5 minutes on water 64" followed by only 4 minutes on combat 52". It doesn't seem realistic that the DB605DC can make 2000hp for longer than the R-2800.

 

It's the same system as before - there are two timers: one for the "combat" power and the second for the "emergency" power. When you are using the combat only the combat's timer ticks. When you are using "emergency" both timers seem to tick. Therefore, the optimum tactic is to start with the combat power and keep it as long possible and only at the end of the engagement switch to the emergency.

 

I agree it's... troublesome. Why it was done such way is a mystery.

[Talon_ 1774]

1 minute ago, Ehret said:

 

It's the same system as before - there are two timers: one for the "combat" power and the second for the "emergency" power. When you are using the combat only the combat's timer ticks. When you are using "emergency" both timers seem to tick. Therefore, the optimum tactic is to start with the combat power and keep it as long possible and only at the end of the engagement switch to the emergency.

 

I agree it's... troublesome. Why it was done such way is a mystery.

 

That's not how it works though. The K-4 gets seperate timers (in fact "emergency" regenerates during Combat)

[Legioneod 2021]

5 minutes ago, Talon_ said:

 

That's not how it works though. The K-4 gets seperate timers (in fact "emergency" regenerates during Combat)

One of the reasons we should just get the full 15min at WEP. American aircraft suffer the most with these engine limitations.

[Ehret 448]

Just now, Talon_ said:

That's not how it works though. The K-4 gets seperate timers (in fact "emergency" regenerates during Combat)

 

All planes have the same system and I wrote just that. When you are on the "emergency" both timers seem to deplete. You can have the whole 15m + 5m but you have to use the combat mode first before the emergency. In the reverse you will get 5m of the latter but much less than 15m for the combat.

[Talon_ 1774]

I made a seperate topic here about how the laws of physics apply differently to American ADI systems: 

 

 

1 minute ago, Ehret said:

 

All planes have the same system and I wrote just that. When you are on the "emergency" both timers seem to deplete. You can have the whole 15m + 5m but you have to use the combat mode first before the emergency. In the reverse you will get 5m of the latter but much less than 15m for the combat.

 

No, that's not the case. The K-4 can run for 45 minutes in the following order:

WEP 1.98 10m

Combat 1.65 10m

WEP 1.98 10m

Combat 1.65 10m

WEP 1.98 5m

 

At which point the water runs out and you either break the engine or reduce back to Combat and fly home as you only have 5 minutes of fuel left in the aircraft. 

 

Proof here: https://streamable.com/ay7rv

[Ehret 448]

Just now, Talon_ said:

I made a seperate topic here about how the laws of physics apply differently to American ADI systems:

 

The Axis planes had much longer and stronger combat modes before BOBP. To match them in the P-39 you would need to use low Emergency and that's good for 5-7m instead of Axis' half of hour.

In the BOBP Axis fighters got 10m of very permissible emergency settings. Twice long the P-47 has now albeit the water injected combat mode trick helps to even odds a little.

[Talon_ 1774]

1 minute ago, Ehret said:

In the BOBP Axis fighters got 10m of very permissible emergency settings. 

 

Yes, unlimited combat/WEP combined while the P-47 has 9 minutes combat/WEP combined using the same water injection technology.

[Ehret 448]

17 minutes ago, Talon_ said:

No, that's not the case. The K-4 can run for 45 minutes in the following order:

WEP 1.98 10m

Combat 1.65 10m

WEP 1.98 10m

Combat 1.65 10m

WEP 1.98 5m

 

I see now...

 

5 minutes ago, Talon_ said:

Yes, unlimited combat/WEP combined while the P-47 has 9 minutes combat/WEP combined using the same water injection technology.

 

Well... you can run the Jug like:

10m of water injected combat mode, first. (set the throttle/rpm to 85%/85% and turn on the injection to enable it)

5m of "normal" emergency water injected mode, second.

 

You will get 15m of elevated performance that way. Of course it's a much shorter than the K4 got. At least some l-w*****s are appeased now but for how long?

Edited November 24, 2018 by Ehret

[Sgt_Joch 284]

I thought the MW50 tank only had enough liquid for 20 minutes?

[Talon_ 1774]

3 minutes ago, Sgt_Joch said:

I thought the MW50 tank only had enough liquid for 20 minutes?

 

24 minutes at 1.98ata in game

[Sgt_Joch 284]

2 hours ago, RoflSeal said:

I am pretty sure the reason for this is because the engine would encounter detonation having such high boost pressures at such low RPM and this is not modelled in the game.

Yup, makes sense, so game anomaly then.

[Rebel_Scum 14]

3 hours ago, Legioneod said:

One of the reasons we should just get the full 15min at WEP. American aircraft suffer the most with these engine limitations.

 

This.

[Silavite 7]

On 11/21/2018 at 9:22 PM, Silavite said:

Although it seems odd, I believe that the speed increase regarding the decreased RPM is historically accurate.

Initially, the P-47 was equipped with a 12' 2" diameter Curtiss 714 propeller, but the later models featured the Hamilton Standard 6501 and Curtiss 836 propellers, both of which had diameters of 13'.

  Reveal hidden contents

All B-series R-2800 engines used in the P-47 featured a reduction gearing of 0.5, so this increase in diameter increased the propeller tip speed past its critical mach number at high altitudes where the speed of sound was lower. As a result, one could get more effective thrust out of the propeller at a slightly lower RPM, where the increase in propulsive efficiency more than made up for the loss in engine horsepower. I can't find any sources directly stating this for the P-47, but the F4U had a similar issue. The relevant report is here, with the relevant data being in Section 4.3 and Table IV.

It is also enlightening to note that if the P-47M or N were ever to be added, this should not be an issue, as their C-series R-2800 engines featured a reduced reduction gearing of 0.45 (Page 3, "Power Plant").

@Sgt_Joch

Edited November 24, 2018 by Silavite

[Sgt_Joch 284]

Interesting. Nice find. 👍

[Cpt_Siddy 1413]

We need to bring old IL-2 planes in line before boddenplatte is released.

 

Today on TAW i was out climbed and caught up by a G-4 that followed me at 10km up to 11.5 and caught up to me in climb. 

 

All this while G-14's could not keep up after 8-9km. 

 

I suspect that there will be many more UFO's in the old IL-2 plane sets that will outperform the "high" altitude planes in BoP 

Edited January 6, 2019 by CptSiddy