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 18 hours ago 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 16 hours ago 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 11 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 10 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 9 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 3 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.