Level flight speed

[Saxman]

34 minutes ago, Rudel_chw said:

 

You maybe are confusing with the F4U-4 specs, the F4U-1 only did 378 mph at 20,000ft.

Source: https://www.wwiiaircraftperformance.org/f4u/f4u.html

 

The F4U-1 without ADI had a top speed of just at 400mph TAS at critical altitude. With the addition of ADI the later F4U-1As and retrofit earlier models reached about 425mph at the upper end. The F4U-1D and C lost about 5-10mph because of increased drag from the knuckle pylons.

Edited yesterday at 04:09 PM by Saxman

[AJaromir]

According to my previous test (before patch 2.9.19.13478 which added WEP switch) I had 396 mph TAS at 20k . I will make new one.

Edited yesterday at 06:22 PM by AJaromir

[-Rudel-]

The Mk.IV test dated December 1944, is probably the best document to use as it's the closest to a F4U-1D test that can be found.

https://www.wwiiaircraftperformance.org/f4u/kd227.pdf

Edited 21 hours ago by -Rudel-

[AJaromir]

32 minutes ago, -Rudel- said:

The Mk.IV test dated December 1944, is probably the best document to use as it's the closest to a F4U-1D test that can be found.

https://www.wwiiaircraftperformance.org/f4u/kd227.pdf

Nice. Seems like I am very close to this. I am looking forward to make the new one.

[Saxman]

2 hours ago, -Rudel- said:

The Mk.IV test dated December 1944, is probably the best document to use as it's the closest to a F4U-1D test that can be found.

https://www.wwiiaircraftperformance.org/f4u/kd227.pdf

Which is odd because there's other performance tests of F4U-1 subvariants on the same site that show speeds approaching 420mph.

[-Rudel-]

Sorry, I derped out on KD227.  It is a Mk.IV, but only because it was built by Good Year.  It's still a -1A.  KD227 build 14658
I'll strike my post out.

Though, of all the F4U-1 tests on that sight, they are all either -1s or -1As.   Not a single -1D.

Now there is a 'Detailed Specification' document that was revised for the -1D.
It states in Paragraph 113a, that the listed data is estimated.  
Under the same paragraph, Note 2 states the data is based off of rated engine powers in Paragraph 503.a...551.b for some propeller specs.
But those documents are missing.  That report is missing a lot of pages.

The data used could have possibly been from a -1A, but won't know until the full report is available.

Edit In, if F4U-1D tests are ever found.  "Clean" should indicate no pylons attached.  Otherwise, the tests should specify the conditions in detail.
 

Edited 20 hours ago by -Rudel-

[Invisibull]

I did some more testing and it's actually very close now (4 kts slower than expected) - at 1000 feet @ 11,142 lbs, no wind, auto rich and WEP engaged. I used the performance data for weight as the M3 chart does not include that parameter.  Once the whistle effect is implemented with historical accuracy, we'll be just about there.  

nullimage.png

[HR-Crumble]

1 hour ago, Invisibull said:

I did some more testing and it's actually very close now (4 kts slower than expected) - at 1000 feet @ 11,142 lbs, no wind, auto rich and WEP engaged. I used the performance data for weight as the M3 chart does not include that parameter.  Once the whistle effect is implemented with historical accuracy, we'll be just about there.  

nullimage.png

How do those WEP settings compare to the settings advised in the F4U-1 manual as they are different power settings to Magnitudes manual. 
 

It states to use a higher MP and Auto-Lean. 2700 RPM / 57.5 MP / Auto Lean at sea level. 

Edited 19 hours ago by HR-Crumble

[Invisibull]

1 hour ago, HR-Crumble said:

How do those WEP settings compare to the settings advised in the F4U-1 manual

Did it again with Auto Lean and MAP showed at 57" in the F2 view.  You'll notice my velocity increased by 2 kts - almost got to M3's 306.

 

 

 

 

null

 

 

[Saxman]

4 hours ago, -Rudel- said:

Sorry, I derped out on KD227.  It is a Mk.IV, but only because it was built by Good Year.  It's still a -1A.  KD227 build 14658
I'll strike my post out.

Though, of all the F4U-1 tests on that sight, they are all either -1s or -1As.   Not a single -1D.

Now there is a 'Detailed Specification' document that was revised for the -1D.
It states in Paragraph 113a, that the listed data is estimated.  
Under the same paragraph, Note 2 states the data is based off of rated engine powers in Paragraph 503.a...551.b for some propeller specs.
But those documents are missing.  That report is missing a lot of pages.

The data used could have possibly been from a -1A, but won't know until the full report is available.

Edit In, if F4U-1D tests are ever found.  "Clean" should indicate no pylons attached.  Otherwise, the tests should specify the conditions in detail.
 

The problem is that after ADI was introduced on the later 1As, (and it WAS introduced in the 1A first, not the 1D) a lot of older machines already in the field were retrofit (Vought was nice to provide mod kits for a lot of the incremental updates to groups already in-theater, like replacement panels to eliminate the top cowl flaps) so you probably had a some war-weary birdcages out there that received 8W engines once spares were delivered. Unfortunately, that kind of makes figuring out what condition the test aircraft are in a pain because you've got a lot of mismatching of configurations thanks to the various Vought mod kits and field kludges, unless they specifically used aircraft pulled right off the assembly line.

17930 on that site is definitely a 1A by serial number, and the speed they're reporting of ~420mph is consistent with the use of ADI (speed without ADI topped out around 400mph). I don't think the prop affected top speed as much as it did the acceleration and rate of climb, so you can't really tell from airspeed whether it has the toothpick or later paddle prop.

Whether or not something is "clean" or not is a problem because we (currently) can't fly in this configuration, unless there's plans to allow us to remove the knuckle pylons in the future (though personally I'd rather just have a Variant added for the 1A).

[-Rudel-]

Well if the AN/ARR-2 antenna can reduce speed by 1 knot, imagine what two large pylons can do.

[AJaromir]

If the pylons are culprit, I have no idea how to reproduce tests.

[HR-Crumble]

4 hours ago, Invisibull said:

Did it again with Auto Lean and MAP showed at 57" in the F2 view.  You'll notice my velocity increased by 2 kts - almost got to M3's 306.

 

 

 

 

null

 

 

Okay thanks for the details.

@-Rudel-are you able to confirm which source we should be using to best get the safe and accurate performance out of our shiny new Corsairs?

Edited 13 hours ago by HR-Crumble

[-Rudel-]

Not yet, the team is evaluating the documents they have, and carefully looking whether or not "clean" means with or without pylons.

[Saxman]

My understanding is the pylons were never removed from the -1D and -4 even when not in use. They were just fit with an aerodynamic cap over the rack mounts. With that being their "default" state I would think that's how Vought or the Navy would run their evaluations, especially if they were pulling aircraft at random.

[GTFreeFlyer]

13 hours ago, Invisibull said:

I did some more testing and it's actually very close now (4 kts slower than expected) - at 1000 feet @ 11,142 lbs, no wind, auto rich and WEP engaged. I used the performance data for weight as the M3 chart does not include that parameter.  Once the whistle effect is implemented with historical accuracy, we'll be just about there.  

nullimage.png

Good info, Bull!  However, just wanted to note that you can't even get close to the published numbers with rich mixture because the fuel burn will be way off, if that's a concern to you.  Have a look at this and you can see the effect of rich vs. auto-lean:

 

[westr]

Does anyone know of a way you can definitely tell if the water injection is working? Aside from activating the water injection switch then pushing to full throttle I can’t seem to tell. Before the last update the green light would glow showing water was low. Now the light does not illuminate for me. 

[Invisibull]

2 hours ago, GTFreeFlyer said:

you can't even get close to the published numbers with rich mixture

Thx GT. You'll also note above that there was an only 2 knots diff between auto lean and auto rich with all else being equal in my speed runs. I think the overarching point is that M3 is in the ballpark, same as what you found with your great F4U Corsair Real-Time Engine Diagnostics Data script, which folks can find here: https://www.digitalcombatsimulator.com/en/files/3346516/  

54 minutes ago, westr said:

Does anyone know of a way you can definitely tell if the water injection is working?

One easy way to know is that when you start hearing the roller coaster clickety clack sound due to high MAP induced engine knock, engaging the water injection will stop the knocking within a few seconds. 

[Saxman]

The fuel pressure gauge on the bottom of the right side instrument cluster has been changed to indicate water pressure. When ADI is on the needle should pop up.

But that's the problem, because there's been times I've been at full throttle and ADI never kicks in even when the master switch is on.

[Rudel_chw]

1 hour ago, westr said:

Does anyone know of a way you can definitely tell if the water injection is working? Aside from activating the water injection switch then pushing to full throttle I can’t seem to tell. Before the last update the green light would glow showing water was low. Now the light does not illuminate for me. 

 

look at the Fuel Pressure gauge, the last patch modified it to show water pressure instead. It should show a positive value when its working: