F4U Turning surprise

[Widewing]

When a maximum effort was called for, even the nights fighters went.... Ticonderoga turns into the wind....

[bozon]

Another view, same Hellcat. F6F-3, early production variant. 377 to 383 mph at MIL power. A bit lighter than the F6F-5, but less power and not as aero clean. The -5 had cleaned up aero, revised windscreen and enough power to push beyond 400 mph at critical altitude.

(Image removed from quote.)

Drag wise, I dont think there is any meaningful change between the -3 and -5. The wind screen was the same, only the small square rear window was removed in the -5, so this is a -3:


and this must be -5:


The only difference in power was that water injection became standard with the -5 though many -3 already had them installed. The only other difference to affect performance was all metal ailerons in the -5 in an attempt to improve roll rate (only slightly AFAIK). Speed-wise a -5 hellcat and a -3 hellcat with added water injection should be very very close.

The 383 mph on MIL power as reported is almost the same as what the AH Hellcat achieves with WEP. I've seen numbers up to 391 mph on MIL power. The WEP max speed is achieved at lower alt than the max MIL speed. If we shift the AH curves so MIL power speed at 23,000 is 391 instead of 380, then the WEP peak speed will just about touch the 400 mph line. Of course, a simple global shift is NOT the right thing to do, but it is a decent local approximation.

[bozon]

The Hellcat wasn't much smaller than the P47, it's incredible how nimble it is, and how well it rates/radius in turns with respect to how it looks, and what it must weigh.

The F6F has bigger wing area than the P-47 by about 10%. It also weights a bit less (not much though).

[Widewing]

Drag wise, I dont think there is any meaningful change between the -3 and -5. The wind screen was the same, only the small square rear window was removed in the -5, so this is a -3:
(Image removed from quote.)

and this must be -5:
(Image removed from quote.)

The only difference in power was that water injection became standard with the -5 though many -3 already had them installed. The only other difference to affect performance was all metal ailerons in the -5 in an attempt to improve roll rate (only slightly AFAIK). Speed-wise a -5 hellcat and a -3 hellcat with added water injection should be very very close.

The 383 mph on MIL power as reported is almost the same as what the AH Hellcat achieves with WEP. I've seen numbers up to 391 mph on MIL power. The WEP max speed is achieved at lower alt than the max MIL speed. If we shift the AH curves so MIL power speed at 23,000 is 391 instead of 380, then the WEP peak speed will just about touch the 400 mph line. Of course, a simple global shift is NOT the right thing to do, but it is a decent local approximation.

Several changes made from the F6F-3 to the F5F-5 were aimed at drag reduction. The cowling was redesigned, with the exhaust bulge removed and careful attention paid to reduce drag from air leaving the oil cooler. Panel fitting was improved, and the lower cowl flaps replaced by carefully designed exhaust vents. The windscreen was redesigned, and shaped via wind tunnel testing. A flat sheet of armored glass was added, and the interior armored glass was removed. Grumman technical reports indicated that drag had been reduced by 4%.

F3F-3 models fitted with the R-2800-10W were capable of 397 to 401 mph using WEP and water injection. In-service aircraft were more likely at the lower end of that range. The F6F-5, when tested by TAIC and Grumman showed about a 10 mph increase over the -3, all of it directly from the reduction in drag.

When the -5 began to arrive in service, squadrons quickly found out that older -3s cruised slower than the new -5. Thus, the -3 pilots had to run at a higher power setting. This cut into their range. Thus, mission planning was based upon the -5 being throttled back some or limiting the range to what the -3 could do with adequate reserve.

[Saxman]

Soi three's pretty good reason to have the -3 and -5 qs two speretqate models
(sorry I'v ehad atbit of bro8urbon tonight).

[bozon]

Several changes made from the F6F-3 to the F5F-5 were aimed at drag reduction. The cowling was redesigned, with the exhaust bulge removed and careful attention paid to reduce drag from air leaving the oil cooler. Panel fitting was improved, and the lower cowl flaps replaced by carefully designed exhaust vents. The windscreen was redesigned, and shaped via wind tunnel testing. A flat sheet of armored glass was added, and the interior armored glass was removed. Grumman technical reports indicated that drag had been reduced by 4%.

OK, thanks for pointing this out. I'll dig deeper into the literature because I do not remember reading about drag reduction before. There's always an opportunity to learn more.
 

[Widewing]

How to tell an F6F-3 from an F6F-5....

Let's use this iconic Life Magazine photo to demonstrate the differences (between -3s too).



Identifying if a particular Hellcat is an F6F-3 or an F6F-5 can be tricky for many. All -3 models have the small windows behind the main canopy. However, some early -5s also had those windows. The first 909 -3s had forward canted radio masts. Later -3s had vertical masts (to the left and right of center), as did the -5s. Not all -5s were painted in overall dark blue.

So, what identifiers or clues help us to determine what version this Hellcat is?
1) Lower cowl flap (omitted after BuNo 39998).
2) Rounded windshield (all-3s).
3) Exhaust bulge on cowling (omitted after BuNo 40234).
4) Straight radio mast (after BuNo 26195).

Since it has the lower cowl flaps, the BuNo of the Hellcat depicted is earlier than 39999. Thus, we know that this is an F6F-3, had a BuNo in the 65890 to 66244 series, and was delivered between July and September of 1943. 30 of this series were delivered to the Royal Navy, and BuNo 66244 was originally assigned to the XF6F-2. From the weathered appearance of the aircraft, odds are delivery was during the early part of that time period.

[Rogue9Volt]

Would it be possible to get some hellcat lessons..?
Always have liked that plane

[Widewing]

Would it be possible to get some hellcat lessons..?
Always have liked that plane

If I'm on the MA roster when you log in, PM me....