A proper heir to the SBD

DBII · Jan 2, 2023

Shortround6 said:
The P-47 gets a bad rap.
Anybody (well aside from Brewster) can make a small airplane go fast with enough power (think Groundhog).
making big planes go fast is a lot trickier.
P-47 has a lower flat plate area (about 25%) than an F4U-1 or an F6F-3.
The P-47 has a flat plate area about 12% larger than a P-40 (model unknown) so considering the size of the P-47 that is not too bad.
The Buffalo had a flat plate area 2% less than the P-47.
There is a genuine cinderblock.

I am not familiar with the term flat plate area. Is that the profile of the bottom of the plane? Uneducated minds want to know.

tomo pauk · Jan 2, 2023

DBII said:
I am not familiar with the term flat plate area. Is that the profile of the bottom of the plane?

A way of expressing the drag of an aircraft.
S = Cd0 x wing_area
S being the 'equivalent flat plate area', Cd0 being the drag coefficient at zero lift (= max speed); wing_area is oboviously wing area.
Smaller S = lower drag.

Hoerner notes that S ('f' in his works) is 5.40 sq ft for the Spit IX, 4.61 for P-51B, and 5.22 for the Fw 190A-8.
Dean notes 5.71 sq ft for a P-40 (version?), only 4.10 sq ft for P-51D, 6.39 for the P-47 (version?), and well above 8 sq ft for the F4U and F6F (F4U is better of the two). P-39 (version?) being at 4.63 sq ft - almost 10% better value thanvthe P-63.

Note: there is also equation of S = Cd_total x wing area, applicable for aircraft in climb. Cd_total is always greater than the Cd0.

DBII · Jan 2, 2023

tomo pauk said:
A way of expressing the drag of an aircraft.
S = Cd0 x wing_area
S being the 'equivalent flat plate area', Cd0 being the drag coefficient at zero lift (= max speed); wing_area is oboviously wing area.
Smaller S = lower drag.

Hoerner notes that S ('f' in his works) is 5.40 sq ft for the Spit IX, 4.61 for P-51B, and 5.22 for the Fw 190A-8.
Dean notes 5.71 sq ft for a P-40 (version?), only 4.10 sq ft for P-51D, 6.39 for the P-47 (version?), and well above 8 sq ft for the F4U and F6F (F4U is better of the two). P-39 (version?) being at 4.63 sq ft - almost 10% better value thanvthe P-63.

Note: there is also equation of S = Cd_total x wing area, applicable for aircraft in climb. Cd_total is always greater than the Cd0.

Always interested in the phsyics of things. Thanks for the reply.

Wild_Bill_Kelso · Jan 2, 2023

tomo pauk said:
A way of expressing the drag of an aircraft.
S = Cd0 x wing_area
S being the 'equivalent flat plate area', Cd0 being the drag coefficient at zero lift (= max speed); wing_area is oboviously wing area.
Smaller S = lower drag.

Hoerner notes that S ('f' in his works) is 5.40 sq ft for the Spit IX, 4.61 for P-51B, and 5.22 for the Fw 190A-8.
Dean notes 5.71 sq ft for a P-40 (version?), only 4.10 sq ft for P-51D, 6.39 for the P-47 (version?), and well above 8 sq ft for the F4U and F6F (F4U is better of the two). P-39 (version?) being at 4.63 sq ft - almost 10% better value thanvthe P-63.

Note: there is also equation of S = Cd_total x wing area, applicable for aircraft in climb. Cd_total is always greater than the Cd0.

Wow I'm really surprised that a Corsair purportedly has more drag than a P-47

tomo pauk · Jan 2, 2023

Wild_Bill_Kelso said:
Wow I'm really surprised that a Corsair purportedly has more drag than a P-47

Why are you surprised?

Wild_Bill_Kelso · Jan 2, 2023

tomo pauk said:
Why are you surprised?

Because I have a couple of 1/72 scale models of both on my shelf three feet away and can eyeball the difference, I've seen both in real life in museums and air shows too, and the Corsair looks like it has a smaller fuselage size and appears to be better streamlined.

I guess it also does matter which P-47, a P-47C is less streamlined than an M.

tomo pauk · Jan 2, 2023

Wild_Bill_Kelso said:
Because I have a couple of 1/72 scale models of both on my shelf three feet away and can eyeball the difference, I've seen both in real life in museums and air shows too, and the Corsair looks like it has a smaller fuselage size and appears to be better streamlined.

Wing t-t-c (root) of the F4U was 18%, P-47 was at 16%. Wing of the P-47C/D/M was at 300 sq ft, that of the F4U was at 314 sq ft.
End result being that wing of the F4U was much draggier, that might cancel out the advantage of sleeker fuselage the F4U had.

F6F offered the worst to the two worlds - deep and draggy fuselage and an even a bigger wing (335 sq ft, even if it was at 15%).

Wild_Bill_Kelso · Jan 2, 2023

tomo pauk said:
Wing t-t-c (root) of the F4U was 18%, P-47 was at 16%. Wing of the P-47C/D/M was at 300 sq ft, that of the F4U was at 314 sq ft.
End result being that wing of the F4U was much draggier, that might cancel out the advantage of sleeker fuselage the F4U had.

F6F offered the worst to the two worlds - deep and draggy fuselage and an even a bigger wing (335 sq ft, even if it was at 15%).

Interesting... but it doesn't seem to translate as a huge speed advantage for the P-47 in spite of the turbo....?

elbmc1969 · Jan 7, 2023

Wild_Bill_Kelso said:
Interesting... but it doesn't seem to translate as a huge speed advantage for the P-47 in spite of the turbo....?

The P-47 did have a notable speed advantage, but only way up where the turbo mattered. The F4U's maximum speed is at a lower altitude; by the time the P-47 hits the wall, the F4U has slowed down a lot. However, Corsairs didn't spend their time trying to fight in the stratosphere.

Wild_Bill_Kelso · Jan 7, 2023

Well considering that P-47s were quite often being used as fighter bombers, many of them didn't either

A proper heir to the SBD

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DBII

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tomo pauk

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DBII

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Wild_Bill_Kelso

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tomo pauk

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Wild_Bill_Kelso

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Wild_Bill_Kelso

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