This Should Have Gone into Production...

[Shuckins]

I can't really buy that argument Joe.  Weight can be offset by horsepower.  Otherwise, how does one explain the following?

P-38G at 15,800 lb. weight had an initial climb rate of 3,700 feet a minute using military power.

P-38L at 17,500 lb. weight had an initial climb rate of 3,700 feet a minute using combat power.

What was the difference between these two models?  Horsepower.  The version of the Allison engine used in the -G model was rated at 1325 hp.  The engine used in the -L was rated at 1,600 hp using combat power.

To quote Francis Dean:  "Increases in engine power usually more than made up for the inevitable airplane weight increase.  P-38J and P-38L fighters, though near a ton heavier than the early P-38s, took at least six minutes off the time getting to 30,000 feet and cut almost two minutes from the time to 25,000 feet.

The P-47D-25 and P-47M, by virtue of a new paddle blade propeller and increased engine power reduced time to 25,000 feet from 15 to 11 minutes, and took six minutes off the P-47C time to 30,000 feet."

Differences in empty weight between the -3 and -5 Hellcats amounted to only 127 lbs.  Since the -5 had water injection the power loadings were nearly identical.  Consequently, the -5 initial climb rate only marginally less than that of the -3.  Climb rate above 15,000 feet was actually greater than that of the -3.

The Corsair shared similar versions of the R2800 engine during their production lives.  Climb performances at similar weights were virtually identical.  Late F4U-1 Corsairs had an itialy climb rate with military power of around 2,900 fpm.  The F4U-4, with the same R2800-18W engine as the XF6F-6, could hit a climb rate of 3,900 fpm using water injection.  The XF6F-6 should have enjoyed a similar increase in climb performance when compared to the -3 and -5 model Hellcats.

Regards, Shuckins

[Squire]

Had the war continued, I think the F8F-1 would have served the USN better, as it was designed as a very fast climbing anti-Kamikaze fighter. Undoubtably the # of such attacks against the Allies in an invasion of Japan would have been very numerous.

Thats not to say that the F6F-6 wouldn't have been a welcome addition, had it come along.

[Shuckins]

Squire,

If Japanese plans for countering Operation Downfall (U.S. invasion of Japan) had come to fruition, they would have had close to 12,000 aircraft on hand.  They hoped to sustain 10 days of massive kamikaze attacks against the invasion fleet and overwhelm it...exhausting it's fighter pilots and running the ships short of ammunition.

Under such circumstances, the far greater endurance of the F6F-6 would have been an invaluable asset, allowing pilots to spend less time taking off, landing, rearming, etc. and would have allowed them to spend more time on CAP.

Regards, Shuckins

[Squire]

Didnt the F8F have a DT?

Im assuming you dont do BARCAP at full throttle.

CC on the Japanese plans, I don't know what their fuel situation would have been like, but I have no doubt they were preparing for a very large Kamikaze campaign, both air and sea.

Also remember, the F8F was a smaller a/c and was slated for use on the CVEs as well, replacing the FM-2.

[Shuckins]

Squire,

The Bearcat carried a single 150 gallon centerline drop tank but less internal fuel than the Hellcat.

The normal mission requirements for the Hellcat saw it equipped with a 150 gallon drop tank, but it was actually capable of carrying two more of these tanks, for an additional  300 gallons of fuel.  While three tanks might be impractical, two would have greatly extended the Hellcat's loiter time.

Regards,  Shuckins

[joeblogs]

The point of power loading is to implement your exact point. If horsepower goes up by more than weight, the power loading statistic goes down. According to the data Francillon had, weight rose proportionately more than did horsepower, and so the power loading rose slightly.

From other work I've done, I know that climb rates are very sensitive to wing loading (wt/wing area). Now switching propellers or supercharger gearing can add some noise to the relationship, but the underlying sensitivity is there. You can find this in any textbook on aerodynamics.

Just looking at the numbers for the P38. Weight goes up 11 percent, and max power by 20 percent so power loading falls quite a bit. This quite likely offsets the 10 percent rise in wing loading. But the comparison is also complicated by the difference in the max spin limits on the different models of GE superchargers used in these two planes.

Go back to Francillon's numbers on the F6 models. Wing loading rises by 3 percent and power loading falls by a little less than 2 percent. In other words, the plane gained relatively more weight than horsepower.

The key question is what horsepower is being used in Francillon's calculation? That is why I say it's important to make comparisons using data derived from the same methodology.

I think the discrepancy is that that not all the additional horsepower of the R2800-16 could be used at sea level, where the initial climb numbers are derived. I don't have a power curve chart for this engine in front of me, but I suspect that the throttle cannot be fully opened for any length of time at sea level without damaging the engine. If I am right, the average climb rate to any significant altitude (say 15-20k) for the xF6f-6 would look as good or better than for the F6f-5.

Originally posted by Shuckins
I can't really buy that argument Joe.  Weight can be offset by horsepower.  Otherwise, how does one explain the following?

P-38G at 15,800 lb. weight had an initial climb rate of 3,700 feet a minute using military power.

P-38L at 17,500 lb. weight had an initial climb rate of 3,700 feet a minute using combat power.

What was the difference between these two models?  Horsepower.  The version of the Allison engine used in the -G model was rated at 1325 hp.  The engine used in the -L was rated at 1,600 hp using combat power.

To quote Francis Dean:  "Increases in engine power usually more than made up for the inevitable airplane weight increase.  P-38J and P-38L fighters, though near a ton heavier than the early P-38s, took at least six minutes off the time getting to 30,000 feet and cut almost two minutes from the time to 25,000 feet.

The P-47D-25 and P-47M, by virtue of a new paddle blade propeller and increased engine power reduced time to 25,000 feet from 15 to 11 minutes, and took six minutes off the P-47C time to 30,000 feet."

Differences in empty weight between the -3 and -5 Hellcats amounted to only 127 lbs.  Since the -5 had water injection the power loadings were nearly identical.  Consequently, the -5 initial climb rate only marginally less than that of the -3.  Climb rate above 15,000 feet was actually greater than that of the -3.

The Corsair shared similar versions of the R2800 engine during their production lives.  Climb performances at similar weights were virtually identical.  Late F4U-1 Corsairs had an itialy climb rate with military power of around 2,900 fpm.  The F4U-4, with the same R2800-18W engine as the XF6F-6, could hit a climb rate of 3,900 fpm using water injection.  The XF6F-6 should have enjoyed a similar increase in climb performance when compared to the -3 and -5 model Hellcats.

Regards, Shuckins

[Shuckins]

Joe,

Dean gives the power of the -3 and -5 Hellcats at the following altitudes:

F6F-3 (R2800-10)  (Military power = high blower operational)

2000   -   military power   -   Sea level

2000   -   military power   -   1000 feet

1800   -   military power   -   13,500 feet

1650   -   military power   -   22,500 feet


F6F-5 (R2800-10W *water injection)  (Combat power = water injection operational)

2250   -   combat power   -   Sea level

2135   -   combat power   -   15,000 feet

1975   -   combat power   -   20,000 feet

1800   -   military power   -   15,500 feet

1650   -   military power   -   22,500 feet


XF6F-6 (R2800-18W)  (With water injection)

2380   -   combat power   -   Sea level

2080   -   combat power   -   23,300 feet

2100   -   military power   -   4,300 feet

1710   -   military power   -   25,000 feet


Hellcat wing loads rose by only 3.2 percent between the -3 and -5 models.  Power loadings were slightly less for the -3 than for the -5 as a consequence.  According to Francillon's data, the XF6F-6's power loading was lower than that of the -3.

Consequently, the -6 should have had a higher rate of climb than the -3 and -5.

Making a few extrapolations based on the above data...the -6 had 400 more horsepower at sea level and at 22,000 feet than the the -3.  Combined with the extra thrust available from the four-bladed Hamilton Standard propeller, this should translate into a substantial increase in climb rate.

Regards, Shuckins

[bkbandit]

wat about the f8f, it came a week late or somethin, just like the p51h

[Shuckins]

bk,

If memory serves, two or three squadrons of Bearcats were enroute to the Pacific Fleet when the war ended.  I don't think enough of them would have been available to make a large impact on the fighting by the time the invasion took place in November.

Regards, Shuckins

[joeblogs]

Yes I goofed, wing loading rose 3 percent, power loading fell about 2 percent. The question is whether performance is more sensitive to either of the two variables, or in other words, what improves climb rate more, an extra foot of wing area or an extra horsepower? I don't know the anser to that.

The interesting comparison is between the -5 and this -6. The airframes are the same. The difference in sea level horsepower is about 100 and yet the climb rate is nearly identical.

-Blogs

Originally posted by Shuckins
Joe,


Hellcat wing loads rose by only 3.2 percent between the -3 and -5 models.  Power loadings were slightly less for the -3 than for the -5 as a consequence.  According to Francillon's data, the XF6F-6's power loading was lower than that of the -3.

Consequently, the -6 should have had a higher rate of climb than the -3 and -5. ...

Regards, Shuckins

[Squire]

Thats correct, there was an F8F sqn en route from Pearl Harbor in August 1945.

[Pongo]

Could the F6F-6 have operated from jeep carriers?
I thought the 5 couldnt, thats why they had to keep the FM-2 in production, and I know the F8F could.

[Widewing]

Originally posted by Pongo
Could the F6F-6 have operated from jeep carriers?
I thought the 5 couldnt, thats why they had to keep the FM-2 in production, and I know the F8F could.

F6Fs squadrons were assigned to CVEs, both in the Pacific and in the MTO, where Hellcats saw quite a bit of combat in support of the invasion of Southern France. These flew from the Tulagi and the Kasaan Bay. In the Pacific, Hellcats deployed aboard the Sangamon, Nassau, Barnes, and Chenango. There were probably more, but I can't think of them off the top of my head.

My regards,

Widewing

[joeblogs]

I think Pongo was asking if they flew from the U.S. carriers built on freighter hulls, used in escort duty in the Atlantic, rather than the ones built on cruiser hulls. The former had shorter decks and were too slow to operate with a taskforce. The latter could, and were used extensively in the pacific.

-Blogs

Originally posted by Widewing
F6Fs squadrons were assigned to CVEs, both in the Pacific and in the MTO, where Hellcats saw quite a bit of combat in support of the invasion of Southern France. These flew from the Tulagi and the Kasaan Bay. In the Pacific, Hellcats deployed aboard the Sangamon, Nassau, Barnes, and Chenango. There were probably more, but I can't think of them off the top of my head.

My regards,

Widewing

[F4UDOA]

Honestly I am not sure what the role of the F6F-6 would have been post WW2.

The arguement then becomes is it worth it to carry four primary fighter types (Non-Jet). The F8F clearly was the short range interceptor and the F7F and F4U-4/5 were the long range fighter bombers.

Sure the performance was up to 425MPH but in 1946 it would have been considered slow. The other A/C were all 450MPH+ not including any of the early jets. Also what was the payload capacity?