Engine Power/Aircraft Speed

[felixx75]

3 minutes ago, Rougaroux said:

Based on that your airspeed is about a hundred knots low off the chart I posted.

How do you get to 100?

Above it says: 343kt @20000 ft

I had about: 316kt @18800ft

Difference: 27kt

[Rougaroux]

17 minutes ago, felixx75 said:

It's True Airspeed. 

You can switch between IAS and TS with STRG+Z (or CTRL+Y, depending on the keyboard layout).

You can see above, that's about 235 kt IAS

from your own post.  You're flying WOT and achieving 235 kts IAS.

At your altitude you should be getting ~343ish knots. You're not quite at 20,000 ft.

I did *not* convert your TA into IAS based on your picture. I just trusted your 235kts was right..isn't it?

[Saxman]

44 minutes ago, Rougaroux said:

Oh really? Show your work.

 

I used the exact same calculator that you did, using what information you provided. If you failed to provide pressure and temperature data to feed into the calculator that's on you.

[Rougaroux]

Just now, Saxman said:

I used the exact same calculator that you did, using what information you provided. If you failed to provide pressure and temperature data to feed into the calculator that's on you.

False. i did provide pressure data. I inputted 29.95 right off the altimeter. Where are you seeing temperature in my screenshots? not being snarky, i'm sure if it was a snake it would have bit me. I just put in 32deg F because it was a lot more likely than the balmy 80deg F that it was at sea level.

[felixx75]

5 minutes ago, Rougaroux said:

from your own post.  You're flying WOT and achieving 235 kts IAS.

At your altitude you should be getting ~343ish knots. You're not quite at 20,000 ft.

I did *not* convert your TA into IAS based on your picture. I just trusted your 235kts was right..isn't it?

...you don't have to convert anything. The TAS values are there... 316 kt (in the cockpit about 235 kt IAS)

EDIT: Ah, now I see what you mean. The values in your table are definitely TAS and not IAS

Edited June 30 by felixx75

[Rougaroux]

2 minutes ago, felixx75 said:

...you don't have to convert anything. The TAS values are there... 316 kt (in the cockpit about 235 kt IAS)

EDIT: Ah, now I see what you mean. The values in your table are definitely TAS and not IAS

And I see what YOU mean. Your IAT was based off cockpit gauge. That one was my fault.

 

I think we're both trying to argue the same point. The engine IS performing properly but it's not getting the speed that it should.  All I was trying to say was advancing it "past the stops" allows it to achieve the rated speed, regardless of needle readings.

Something is off, whether it be drag, the gauges, or the actual speed performance.  With the Corsair we have right now an FW-190 can and will run away from you and that should not be the case. The only way we currently have of fixing that performance is by utilizing a bug.

For the record I fully agree we should fully be frying bearings at 3500-4000 rpm (and 4200 is INSANE)

[felixx75]

10 minutes ago, Rougaroux said:

And I see what YOU mean. Your IAT was based off cockpit gauge. That one was my fault.

 

I think we're both trying to argue the same point. The engine IS performing properly but it's not getting the speed that it should.  All I was trying to say was advancing it "past the stops" allows it to achieve the rated speed, regardless of needle readings.

Something is off, whether it be drag, the gauges, or the actual speed performance.  With the Corsair we have right now an FW-190 can and will run away from you and that should not be the case. The only way we currently have of fixing that performance is by utilizing a bug.

For the record I fully agree we should fully be frying bearings at 3500-4000 rpm (and 4200 is INSANE)

I would still very much like to see a detailed performace table for F4U-1D (and not a comparison table). No offense, but this small excerpt you posted is quite poor and says relatively little, as you have no data on the circumstances or similar.

I am also sure that a FW 190-D9 was faster than a F4U-1D

[Rougaroux]

2 minutes ago, felixx75 said:

I would still very much like to see a detailed performace table for F4U-1D (and not a comparison table). No offense, but this small excerpt you posted is quite poor and says relatively little, as you have no data on the circumstances or similar.

I am also sure that a FW 190-D9 was faster than a F4U-1D

exactly what data are you looking for? A buddy just bought me a birthday Spitfire so I've got a bit to look while it's downloading.  I'll be happy to search for a bit.

[felixx75]

8 minutes ago, Rougaroux said:

A buddy just bought me a birthday Spitfire

Great airplane, lots of fun! 

[Saxman]

1 hour ago, Rougaroux said:

False. i did provide pressure data. I inputted 29.95 right off the altimeter. Where are you seeing temperature in my screenshots? not being snarky, i'm sure if it was a snake it would have bit me. I just put in 32deg F because it was a lot more likely than the balmy 80deg F that it was at sea level.

That was my point entirely; neither the pressure or temperature were in the screenshots or in your post commentary so I had to make a guess when filling out the calculator on my end.

[Dkha]

4 hours ago, Rougaroux said:

it doesn't even get there with WEP. These pictures are with WEP on and off at 18,500 feet.  Top is WEP off, bottom is WEP on (after at least 5 minutes..my green warning light was on)

 

 

I just flew level a little while ago and managed to reach 266 knots without water injection. Then I tried with injection and didn’t notice any difference at all (throttle at maximum + pressed the injection button). After a few minutes the green light came on, but the speed didn’t change at all.

Screen_250630_184546.bmp Screen_250630_184550.bmp

[Rougaroux]

45 minutes ago, Dkha said:

I just flew level a little while ago and managed to reach 266 knots without water injection. Then I tried with injection and didn’t notice any difference at all (throttle at maximum + pressed the injection button). After a few minutes the green light came on, but the speed didn’t change at all.

Screen_250630_184546.bmp 5.93 MB · 3 downloads Screen_250630_184550.bmp 5.93 MB · 0 downloads

I had to bind it to keyboard to get WEP to engage. It didn't work by mapping a throttle button. Try that maybe?

[fargo007]

 

Their testing also shows that there's something up, whether it's the rpms being misreported or what. Regardless, neither a bf-109 nor a fw-190 should outrun this airplane at sea level. At "presently indicated" 2700rpm, they do so easily. 

It could also be that the rpms and the torque curve produced by it aren't lining up as they should. 

None of us have any information to really say. All we can do is observe:  "it should be faster than these other airplanes, and it isn't." 

 

Edited July 1 by fargo007

[Saxman]

3 hours ago, Rougaroux said:

I had to bind it to keyboard to get WEP to engage. It didn't work by mapping a throttle button. Try that maybe?

It's possible that the water injection simply isn't working at all, and that could explain a lot.

According to this chart:

the F4U-1D at 18,000ft would have a speed of about 385mph TAS at MIL power, and just about 400mph under WEP.

I would say that 385mph TAS falls within an acceptable margin of error for your test, varying on temperature and pressure conditions, as well as excess drag slowing your acceleration.

[felixx75]

There is no reason to assume that water injection would not work. In the F4U, unlike the P-47, for example, there is no switch to activate the system. Water injection is activated by pushing the throttle lever all the way forward. This activates a microswitch, which switches on the water injection. This microswitch can be operated manually with a screwdriver, e.g. to fill the system for maintenance purposes (see the familiar manual).

There is a safety wire at the throttle quadrant, which is unfortunately not animated in the simulation and is always cut (there is one in our P-51, for example). But there is an animated detent (like the afterburner detent in jets). You can observe this very well in the simulation. So if you move the throttle lever all the way forwards, beyond the detent (Throttle at the Detent = Mil. Power), WEP is activated (WEP = Mil. Power + Water Injection). You can see this by the fact that you then reach the corresponding MP values that we now know from the familiar table (also at the corresponding altitudes). If there were no water injection, we would not achieve these values either.

In addition, several people have already reported that the 3-minute water warning was triggered for them.

So I assume that if certain top speeds are not reached, this is either due to incorrect drag values, or the power of the engine is calculated incorrectly. But the basic behaviour of the engine clearly seems to be correct.

But of course I can't rule out the possibility that the entire engine simulation is wrong. After all, I didn't programme it. I can only start from my observations and compare them with the known values. And from this I can see that the motor appears to be working correctly.

Edited July 1 by felixx75

[tekwoj]

22 hours ago, Rougaroux said:

Since it got deleted in the other thread, here's the speed comparison between the Fw-190 and the F4u

I just did a test run and I cannot hit these numbers at any speed, any configuration at any altitude with the prop pitch at 2700 rpm and the engine at straight & level flight, with or without WEP.

Knots are in plain numbers, MPH is in (###).

Do you know which F4U variant is this for? The 1D is slower (by about 15kts IIRC) than the other variants.

[felixx75]

1 hour ago, tekwoj said:

Do you know which F4U variant is this for? The 1D is slower (by about 15kts IIRC) than the other variants.

Unfortunately, I have no information at all about this table. No information as to which variants participated or under what circumstances and conditions this data was obtained. For me, this serves more as a rough approximation of what could be achieved than as absolute proof of what must be.

[Mike Busutil]

19 hours ago, tekwoj said:

Do you know which F4U variant is this for? The 1D is slower (by about 15kts IIRC) than the other variants.

Most likely its referring to the initial standard production model F4U-1 which was the most mass produced version. Its performance data of 335 mph at 15,000' is consistent with the F4U-1's known capability's. 

[felixx75]

8 minutes ago, Mike Busutil said:

Most likely its referring to the initial standard production model F4U-1 which was the most mass produced version. Its performance data of 335 mph at 15,000' is consistent with the F4U-1's known capability's. 

That's the problem. There were 4 variants of the F4U-1: A, B (=british F4U-1A, C and D, with A and D having the largest numbers. But they certainly had different performance. As long as we can't prove it with documents, it's hard to say that something needs to be changed. "It was known for..." does not count.

It would be really nice if someone had or could find reliable documents.

[tekwoj]

2 hours ago, felixx75 said:

That's the problem. There were 4 variants of the F4U-1: A, B (=british F4U-1A, C and D, with A and D having the largest numbers. But they certainly had different performance. As long as we can't prove it with documents, it's hard to say that something needs to be changed. "It was known for..." does not count.

It would be really nice if someone had or could find reliable documents.

We need that other military game players to use their superpowers  

[DSR_T-800]

5 hours ago, felixx75 said:

That's the problem. There were 4 variants of the F4U-1: A, B (=british F4U-1A, C and D, with A and D having the largest numbers. But they certainly had different performance. As long as we can't prove it with documents, it's hard to say that something needs to be changed. "It was known for..." does not count.

It would be really nice if someone had or could find reliable documents.

The documents of the F4U-1A and 1D are on https://web.archive.org/web/20250324012447/http://wwiiaircraftperformance.org/ and have been shared on this forum multiple times. F4U-1d is slower than the F4U-1a due to its wing racks/knuckles) by 8mph(SL) and 12mph(Crit. ALT).

The real problem is peoples inability to find consistency in their own data. I've read anyway from 250kt - 315kt @ SL. Some don't post wind or tempeturate, others can't get the right manifold pressure, and perhaps some aren't paying attention the turn and slipe indicator.

[Art-J]

Yup, I also found 16 scans from now defunct wwiiaircraftperformance site on my old drive, with various flight tests, including 14 that are supposed to represent "F4U-1" or their Goodyear or British equivalents.

The problem is, most of them refer to "-1" in general sense, without going deeper whether it's A, C, D or whatever. Some of them can be kind of narrowed down by photos (birdcage vs bubble) or by extra data (-8 vs -8W engine etc.). Some of them have serial numbers given for test airframe - if we could find which numbers correponded to which variants, that would be a clear cut case of which docs we can use as reference for "our" -1D.

[PL_Harpoon]

Perhaps this can be of use:

Corsair f4u-1d-detail-specification.pdf

[DSR_T-800]

57 minutes ago, PL_Harpoon said:

Perhaps this can be of use:

Corsair f4u-1d-detail-specification.pdf 1.44 MB · 3 downloads

Nice, we can cross reference that with this document. Unfortunately the document you shared doesn't tell us the highspeed at SL.  So, we'll have to compare 'Normal' power settings instead(1675hp/2550rpm). Also there is no mention of wingracks/knuckles.

Fighter 12,086lbs vs 12175lbs
Normal SL 317 vs 321
Combat ALT 416 vs 409

Certainly gives us a ballpark of the expected speed.

[tekwoj]

20 hours ago, Art-J said:

Yup, I also found 16 scans from now defunct wwiiaircraftperformance site on my old drive, with various flight tests, including 14 that are supposed to represent "F4U-1" or their Goodyear or British equivalents.

The problem is, most of them refer to "-1" in general sense, without going deeper whether it's A, C, D or whatever. Some of them can be kind of narrowed down by photos (birdcage vs bubble) or by extra data (-8 vs -8W engine etc.). Some of them have serial numbers given for test airframe - if we could find which numbers correponded to which variants, that would be a clear cut case of which docs we can use as reference for "our" -1D.

That's the most comprehensive manufacturing number list I could find http://cgibin.rcn.com/jeremy.k/cgi-bin/gzNavySearch.pl?target=F4U