Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Shuckins on August 07, 2006, 09:45:30 AM
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(http://perso.wanadoo.fr/christophe.arribat/stoff6f6.jpg)
Peak output of the R2800-18w powerplant was 2450hp at sea-level with water injection.
Top speed at 25,000 feet was 425mph.
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What is that AC? Looks like a F6 or something to my untrained eye
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F6F-6?
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Right , it's an XF6F6
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Masherbrun was first with the correct identification.
Congratulations! You win a cookie! :D
I have searched many times for more information on this aircraft's performance in the areas of climb, etc. but haven't been able to find any.
This aircraft could have been in use on the carriers by summer of 1945. I always thought it was a mistake for Grumman not to have put it into production.
Regards, Shuckins
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IIRC, this had a top speed of around 417mph. The Navy wanted this to replace the -5 (and based on the -5 platform) because of performance gains "all over the board". But the end of WWII cancelled production. I want to say their tailcodes were 70188 and 70913 but don't quote me on it.
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Originally posted by Shuckins
Masherbrun was first with the correct identification.
Congratulations! You win a cookie! :D
I have searched many times for more information on this aircraft's performance in the areas of climb, etc. but haven't been able to find any.
This aircraft could have been in use on the carriers by summer of 1945. I always thought it was a mistake for Grumman not to have put it into production.
Regards, Shuckins
pffff he forgot the X ;)
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Originally posted by straffo
pffff he forgot the X ;)
:rofl
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That's better than 10 cookies !
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Two places to look are Rene Francillon's book on Grumman aircraft and Barrett Tillman's Hellcat.
-Blogs
Originally posted by Shuckins
Masherbrun was first with the correct identification.
Congratulations! You win a cookie! :D
I have searched many times for more information on this aircraft's performance in the areas of climb, etc. but haven't been able to find any.
This aircraft could have been in use on the carriers by summer of 1945. I always thought it was a mistake for Grumman not to have put it into production.
Regards, Shuckins
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Originally posted by Masherbrum
IIRC, this had a top speed of around 417mph. The Navy wanted this to replace the -5 (and based on the -5 platform) because of performance gains "all over the board". But the end of WWII cancelled production. I want to say their tailcodes were 70188 and 70913 but don't quote me on it.
Grumman claimed a max speed of 435 mph. I've seen published climb rates for the XF6F-6 that were below that of the F6F-5. This is typical of the non-technical writers dabbling i aviation history. They often publish MIL power performance rather than Combat power ratings. I don't have the Grumman data handy, but I recall that its climb rate was virtually identical to the F4U-4, while having considerably greater internal fuel capacity.
Ultimately, it was the Navy that elected to produce the F8F-1 instead of the F6F-6.
Since the F6F production could be quickly adapted to the revised aircraft, Grumman's manufacturing management wanted the F6F-6 to go into production immediately. Bob Hall (Director of the Experimental Department) wanted his F8F to get the nod. Arguments were made to Roy Grumman. Grumman, who saw great merit in both aircraft formally asked the Navy to make a decision. Not surprising, there were advocates of both types within the Naval Aviation hiarchy. However, it was determined that the F6F-5 was adequate for the short term and a new production line was being tooled-up for the F8F, thus the Bearcat was selected.
Had the F6F-6 been selected, Grumman would have been began delivering these by November of 1944, meaning it would have been in combat no later than January of 1945, months before the F4U-4. Originally, the Navy planned to phase in the F6F-6 as they did the F6F-5, sending them to combat units as replacement aircraft as well as refitting units coming back from deployments. We all know that the F8F didn't see combat, although it was deployed on carriers enroute to Japan at the surrender.
I have always been an advocate of "a good solution in a timely fashion is always more desirable than a perfect solution too late". If I had to make the choice between the F6F-6 and the F8F-1, I would have picked the improved Hellcat as this would have placed better aircraft in the fleet sooner. However, I would also have gotten F8F production underway at Eastern Aircraft ASAP, stopping FM-2 production immediately. Of course, the politics of such a decision would not have sat well with Grumman. Eastern did receive a contract for the FM3-1 (F8F-1) in February of 1945, but hadn't yet begun basic assembly when the war ended (largely because the obsolete FM-2 was consuming much of Eastern's resources). Another reason for selecting the F6F-6 was that F4U-4 production was typically slow. Grumman was delivering Hellcats at nearly twice the rate F4Us were being delivered, and the F4U was being manufactured by Vought and Goodyear (and Brewster, until their pathetic delivery and quality control resulted in a cancelled contract). Getting better aircraft to the fleet as fast as possible would weigh heavy on my thinking.
My regards,
Widewing
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These are from francillon, who had access to the Grumman archives.
I include the more common models for comparison
________________F6f-3____F6f-5____xF6f-6
wing loading______37.2_____38.1___ _38.2
(lb/sq ft)
power loading_____ 6.2______6.4_____6.1
(lb/hp)
max speed_______375_______380____ 417
(mph/ft)________17,300____23,400___21,900
climb rate________3,500_____2,980___3,070
(ft/min)
service ceiling____38,400____37,300___39,000
(ft)
normal range_____1,090_______945___1,170
(miles)
max range_______1,590______1,355___1,730
(miles)
-blogs
Originally posted by Shuckins
Masherbrun was first with the correct identification.
Congratulations! You win a cookie! :D
I have searched many times for more information on this aircraft's performance in the areas of climb, etc. but haven't been able to find any.
This aircraft could have been in use on the carriers by summer of 1945. I always thought it was a mistake for Grumman not to have put it into production.
Regards, Shuckins
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There are some things about Francillon's data that don't add up for me.
How could the XF6F-6 with a lower power loading, 450 more horsepower, a Hamilton-Standard propeller with four 6501 blades instead of three, have a climb rate almost 500 feet a minute less than that of the F6F-3?
Secondly, the 380 mph top speed for the F6F-5 is in error. This model of the Hellcat had been tweaked to provide a higher top speed than that of the -3 model: A smaller engine cowling to reduce drag; replacement of the two-tone, non-specular (flat) paint finish with a glossy enamel with highly polished wax job; and a water injection system. It seems highly unlikely that these improvements would have produced only a 5mph increase over the top speed of the -3.
Francis Dean's tome "America's Hundred Thousand" records the following fact: In January of 1944 a modified F6F-3, including some of the features to be included in the later F6F-5 version, is flown at a high speed of 410mph at 21,000 feet altitude.
The actual top-speed has been a matter of considerable debate and speculation on these boards in the past...but NAS combat tests with a A6M5 revealed a top speed of 409mph. Chance-Vought's tests of a -5 Hellcat also showed a top speed in excess of 400mph.
The 417mph top speed for the XF6F-6 is recorded at an altitude of 23,400 feet. Dean states, however, that the top speed of 425mph came at an altitude of 25,000 feet.
Regards, Shuckins
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Originally posted by Shuckins
There are some things about Francillon's data that don't add up for me.
How could the XF6F-6 with a lower power loading, 450 more horsepower, a Hamilton-Standard propeller with four 6501 blades instead of three, have a climb rate almost 500 feet a minute less than that of the F6F-3?
Secondly, the 380 mph top speed for the F6F-5 is in error. This model of the Hellcat had been tweaked to provide a higher top speed than that of the -3 model: A smaller engine cowling to reduce drag; replacement of the two-tone, non-specular (flat) paint finish with a glossy enamel with highly polished wax job; and a water injection system. It seems highly unlikely that these improvements would have produced only a 5mph increase over the top speed of the -3.
Francis Dean's tome "America's Hundred Thousand" records the following fact: In January of 1944 a modified F6F-3, including some of the features to be included in the later F6F-5 version, is flown at a high speed of 410mph at 21,000 feet altitude.
The actual top-speed has been a matter of considerable debate and speculation on these boards in the past...but NAS combat tests with a A6M5 revealed a top speed of 409mph. Chance-Vought's tests of a -5 Hellcat also showed a top speed in excess of 400mph.
The 417mph top speed for the XF6F-6 is recorded at an altitude of 23,400 feet. Dean states, however, that the top speed of 425mph came at an altitude of 25,000 feet.
Regards, Shuckins
The extra weight of the engine, prop?
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Power loading is weight to horsepower. Lower is better. While thexF6-6 has a slightly better power loading, it has a higher wingloading, which translates into a generally poorer climb performance. In short it's the extra weight on the plane when the -5 when into production.
We've all heard the stories about the pitot tube of the -3. But you don't want to use different methods to make a comparison of the speed between two different versions of the plane. Otherwise we wind up in an apples and oranges comparison of relative performance. In particular, the other tests were done at different weights. What if we took 400lbs off the xF6-6?....
Fact is the 380 number is based on a navy test with the official military weight. If you think it's really 400MPH, then add 20 to the top speed of the other models too.
In terms of drag you see similar exercises with the Spitfire. If you read Alfred Price's Spitfire story, you see lots of examples of experiments with the surface of the plane that resulted in changes of 3-5 MPH.
-Blogs
Originally posted by Shuckins
There are some things about Francillon's data that don't add up for me.
How could the XF6F-6 with a lower power loading, 450 more horsepower, a Hamilton-Standard propeller with four 6501 blades instead of three, have a climb rate almost 500 feet a minute less than that of the F6F-3?
Secondly, the 380 mph top speed for the F6F-5 is in error. This model of the Hellcat had been tweaked to provide a higher top speed than that of the -3 model: A smaller engine cowling to reduce drag; replacement of the two-tone, non-specular (flat) paint finish with a glossy enamel with highly polished wax job; and a water injection system. It seems highly unlikely that these improvements would have produced only a 5mph increase over the top speed of the -3.
Francis Dean's tome "America's Hundred Thousand" records the following fact: In January of 1944 a modified F6F-3, including some of the features to be included in the later F6F-5 version, is flown at a high speed of 410mph at 21,000 feet altitude.
The actual top-speed has been a matter of considerable debate and speculation on these boards in the past...but NAS combat tests with a A6M5 revealed a top speed of 409mph. Chance-Vought's tests of a -5 Hellcat also showed a top speed in excess of 400mph.
The 417mph top speed for the XF6F-6 is recorded at an altitude of 23,400 feet. Dean states, however, that the top speed of 425mph came at an altitude of 25,000 feet.
Regards, Shuckins
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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
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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.
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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
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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.
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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
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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
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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
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wat about the f8f, it came a week late or somethin, just like the p51h
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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
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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
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Thats correct, there was an F8F sqn en route from Pearl Harbor in August 1945.
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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.
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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
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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
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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?
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Originally posted by 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
Ah... All those listed WERE Escort Carriers, not CVLs (like the San Jacinto, Bataan and Langley). In the Pacific, CVEs were extensively used for invasion support. They were usually populated by FM-2s and TBMs, but F6Fs were assigned to them as well and eventually would have largely replaced the FM-2s had the war gone on another 6 months.
Don't confuse CVEs with CVLs. There were several different classes of CVEs (Commencement Bay class, Bogue class, Casablanca class, Chenango class and the on-off Long Island), but only one class of CVLs (Independence class, built on Cleveland class Cruiser hulls) that saw combat. Escort Carriers saw combat in the Pacific, Atlantic and the Med.... But they made Naval history and fought and won the greatest naval victory in the history of the US Navy off of Samar... Even more impressive than Midway... Yet, few Americans ever heard of this battle.
Anyway, as I said, F6Fs were assigned to and operated off of Escort Carriers (CVEs), I was not confusing them with CVLs.
My regards,
Widewing
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Slow? The P-51D hit 435mph at 25,000 feet, a mere 10mph faster than the F6F-6.
Most combat against the Japanese came at altitudes of 15,000 feet altitude or less. The outstanding speed advantage of the P-47 did not become evident until 30,000 feet or more were reached. Late model P-38s had a top speed of only 417mph. The F4U-4 had a top speed of 445mph at 25,000 feet...leading the pack at altitudes of 25,000 feet or less.
In all likelihood, the -6 Hellcat would have been as fast, if not faster, than any of the Japanese fighters in mass production at the war's end.
I'm with Widewing on this. Grumman could have delivered this aircraft to the fleet as early as January of 1945, and it would have been available in large numbers by the time of the invasion of Japan, where it would have been sorely needed.
Regards, Shuckins
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It just occurred to me that the climb rate calculations used in the military tabulations must be based on a sustained climb and it's quite possible that you can't fly these planes at WEP in a climb for more than a minute or so. The forward speed of the plane at the optimum climb angle may be too slow to allow for adequate cooling.
If I am right, the xF6f-6 would have a distinct advantage for a short climb, but not necessarily an advantage in a sustained climb.
-Blogs
Originally posted by 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
F6F-5 (R2800-10W *water injection) (Combat power = water injection operational)
2250 - combat power - Sea level
XF6F-6 (R2800-18W) (With water injection)
2380 - combat power - Sea level
Regards, Shuckins
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Shuckins,
By 1945 the P-51D was hitting 450MPH+ easily. That 437MPH top speed is very conservative for a P-51B/C or D.
The XF6F-6 is an X plane that in the picture shown does not even have external stores pylons or rocket stubbs. The P-51D/P-47D?P-38L/F4U-1D and F4U-4 all had their speeds listed with pylons.
In the clean condition the F4U-4 had a top speed of over 460MPH and 451MPH with Pylons.
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Originally posted by F4UDOA
Shuckins,
By 1945 the P-51D was hitting 450MPH+ easily. That 437MPH top speed is very conservative for a P-51B/C or D.
The XF6F-6 is an X plane that in the picture shown does not even have external stores pylons or rocket stubbs. The P-51D/P-47D?P-38L/F4U-1D and F4U-4 all had their speeds listed with pylons.
In the clean condition the F4U-4 had a top speed of over 460MPH and 451MPH with Pylons.
In the ETO, 8th AF Mustangs were using 150 octane fuel. However, they were not using this in the MTO, PTO or SWPA. These theaters were flying with standard 100/130 avgas. These P-51s were not going to be doing 450+ mph. P-51B/C types were rated at 440 mph at best altitude on 100/130.
The two XF6F-6 prototypes were built from F6F-5s taken from the production line (they retained their F6F-5 serial numbers).
A 425 mph Hellcat was more than fast enough for anything Japan had to offer in reply.
My regards,
Widewing
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Widewing,
I am talking about contemporary A/C speeds.
The F6F-6 was still slower by at least 20MPH than other current Navy fighters in January 1945 two of which were Grumman products. The comparison to the speed of the P-51D cannot be made. Even the P-51A was significantly faster at low altitudes.
Mustang Speeds (http://www.spitfireperformance.com/mustang/mustangtest.html)
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there one thing nobody can argue wit.... hellcat rocks. I fly it relgiously along wit the corsair. In the 10 to 15k window she is great, it just sucks that her performance dies above 18k. She is great, on a sortie a couple of minutes ago i baged 2 lancesters and a tempest(of course nobody else protects the cv and they sink it :lol ).
Alot of times i forget that the raf flew them in the eto, i could have sworn i rewad somewhere that they equiped them wit cannons(dont quote me on it) just like they did wit the mustang. Cannons would be cool but it might kill ur agility, look at the f4u1c and 1d or f4u1, the cannon corsair doesnt move aswell.
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Widewing,
That's the first I've read or heard of the different theaters of operations not having aviation fuels of the same octane rating.
Was it due to a lack of availability? Would naval fighters have performed better with the 150 octane fuel...or were they designed to take the 100/130 octane fuels and thus not realize any benefit from the more volatile fuel?
Admittedly, I know very little about how engines designed for the lower octanes performed when a higher octane was substituted.
Regards, Shuckins
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Originally posted by Shuckins
Widewing,
That's the first I've read or heard of the different theaters of operations not having aviation fuels of the same octane rating.
Was it due to a lack of availability? Would naval fighters have performed better with the 150 octane fuel...or were they designed to take the 100/130 octane fuels and thus not realize any benefit from the more volatile fuel?
Admittedly, I know very little about how engines designed for the lower octanes performed when a higher octane was substituted.
Regards, Shuckins
150 octane fuel was manufactured by the Brits and used by the RAF and the 8th AF. It added substantial performance at the expense of some reliability. You can read about it in detail on this website (http://www.spitfireperformance.com/150grade/150-grade-fuel.html)
My regards,
Widewing
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There were capacity constraints on avgas with a performance rating above 100/130 for most of the war. 150pn fuel was particularly scarce and using it required additional engine maintenance. Given that German A/C speeds were considerable higher than for nearly all Japanese production models, the need was greatest in Europe.
I do not know whether or not the British manufacture 150pn avgas. I do know that most of the world's capacity was located in the U.S.
We have Johnny Doolittle to thank for having adequate capacity for 100/130 pn fuels. In the late 1930s, while working for one refiner (I think it was Shell) he spent considerable time jawboning US industry to build new facilities to make this fuel, even before the airforce was willing to accept it.
Using a lower octane fuel in an engine designed for higher octanes means that it cannot be run anywhere near the designed maximum manifold pressure. If you did, the fuel would "detonate" and damage the cylinders. The result is that you would have to run the engine more conservatively and you would get significantly less performance out of the engine.
A very significant share of the rising output of aviation engines from the mid 1930s to 1950 is the direct result of adopting higher pn fuels, which permitted higher manifold pressure and therefore more supercharging. The evolution of the British Merlin is probably the best example for a production model.
BTW all the US aircraft performance charts issued by the airforce & navy indicate what fuel is being used.
-Blogs
Originally posted by Shuckins
Widewing,
That's the first I've read or heard of the different theaters of operations not having aviation fuels of the same octane rating.
Was it due to a lack of availability? Would naval fighters have performed better with the 150 octane fuel...or were they designed to take the 100/130 octane fuels and thus not realize any benefit from the more volatile fuel?
Admittedly, I know very little about how engines designed for the lower octanes performed when a higher octane was substituted.
Regards, Shuckins
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Widewing,
From the charts, if I may summarize a bit, it seems that most aircraft tested with 150 octane av fuel realized average gains in performance of:
Approximately 15mph in top speed. Some considerably more than this.
About 500fpm increase in rate of climb.
Is that a fair summary? Would the "official" top speeds posted by the Navy reflect the use of 130 or 150 octane fuels?
If the listed speeds were for 130 octane fuels, could we expect similar gains of 15mph and 500fpm for naval fighters such as the -5 Hellcat?
Regards, Shuckins
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I think I have seen some postwar SEFC charts for very late models of the Corsair that are based on 150 PN fuels.
I'll bet F4udoa has those charts.
-blogs
Originally posted by Shuckins
Widewing,
From the charts, if I may summarize a bit, it seems that most aircraft tested with 150 octane av fuel realized average gains in performance of:
Approximately 15mph in top speed. Some considerably more than this.
About 500fpm increase in rate of climb.
Is that a fair summary? Would the "official" top speeds posted by the Navy reflect the use of 130 or 150 octane fuels?
If the listed speeds were for 130 octane fuels, could we expect similar gains of 15mph and 500fpm for naval fighters such as the -5 Hellcat?
Regards, Shuckins
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What I am also curious about is why did General Motors make the FM-1 and FM-2 (Wildcat) as opposed to constructing the Hellcat under licence when Grumman went to F6F production in 1943?
Was there a demonstrated need for the smaller Wildcat on the CVEs? or was it some other reason that the Hellcat was only produced by Grumman?
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Three reasons.
First the wildcat needed less room to clear a carrier deck, so that was best for the CVs escorting convoys in the Atlantic.
Second, this kind of escort did not require high altitude performance, so the complexity of a two stage supercharger could be omitted.
Third, the wildcat could be paired with the Wright Cyclone 9 cylinder, which was available in quantity. Pratt and Whitney's Double Wasp, while manufactured in huge quantities during the war, was always in short supply.
The cylone turned out to be a nice engine for the wildcat because, at sea level it developed more horsepower than the P&W twin-wasp it replaced. So the climb rate of the FM-2 was actually better than the F4f-4.
-Blogs
Originally posted by Squire
What I am also curious about is why did General Motors make the FM-1 and FM-2 (Wildcat) as opposed to constructing the Hellcat under licence when Grumman went to F6F production in 1943?
Was there a demonstrated need for the smaller Wildcat on the CVEs? or was it some other reason that the Hellcat was only produced by Grumman?
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JoeBlogs,
I have those charts for the R2800-18W and 32W(Without looking). I think I already scanned them. I have some -5 and AU-1 NAVAIR rating as well.
I have no evidence that the R2800-8 or -10 could be run with 100/130 fuel as the B blocks were not rated for it. I have seen where a F4U-1 was run at 65" MAP with ADI however.
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Now I'm confused.
Widewing stated that 150 octane fuels were not used in the PTO, but F4UDOA you state the you have no evidence that the R2800-8 or -10 could run with 100/130 octane fuels because the B blocks were not rated for it.
If the Merlin engine of the Spit V could be run with it then why not the R2800-8 or -10?
Regards, Shuckins
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Didnt they go to 115/145 fuel in the PTO in 1945?
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I am looking at the Andrews article on the F6f that includes a Standard Aircraft Characteristics chart from 1949 that is based on 100/130 PN avgas.
The R2800-10 is a B series of the Double Wasp. All my data from Wilkinson suggests this engine was rated on 100/130 PN fuel. The A series engine was rated on only 100 PN, and many of the C series engines were rated on 100/145 PN fuel. It's quite possible those engines appeared in the postwar Corsair.
-Blogs
Originally posted by F4UDOA
JoeBlogs,
I have those charts for the R2800-18W and 32W(Without looking). I think I already scanned them. I have some -5 and AU-1 NAVAIR rating as well.
I have no evidence that the R2800-8 or -10 could be run with 100/130 fuel as the B blocks were not rated for it. I have seen where a F4U-1 was run at 65" MAP with ADI however.
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It's possible since the P47-N could likely use it, but I've not seen any records of it.
-Blogs
Originally posted by Squire
Didnt they go to 115/145 fuel in the PTO in 1945?
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As an aside there was at least one model of the Merlin (24) rated for 150 PN fuel and two Griffons (69, 72) rated for 115/145 avgas.
There were a number of postwar Griffons & Merlins rated for these high PN fuels.
There were two Cyclone 18 models rated for 150 PN fuels (-26 and -30); I think these were post war models.
There is even one model of the Cyclone 9 rated on this fuel.
-Blogs
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Originally posted by F4UDOA
JoeBlogs,
I have those charts for the R2800-18W and 32W(Without looking). I think I already scanned them. I have some -5 and AU-1 NAVAIR rating as well.
I have no evidence that the R2800-8 or -10 could be run with 100/130 fuel as the B blocks were not rated for it. I have seen where a F4U-1 was run at 65" MAP with ADI however.
I suggest you review the specific engine charts for aircraft powered by the R2800.... All R-2800s used in US fighters were rated for 100/130 avgas. All B Block R2800s used in the F6F and F4U, as well as the P-47s were not only rated for 100/130, but had restrictions on MAP if using 100 octane fuel (typically used for transport, utility and trainers).
(http://www.zenoswarbirdvideos.com/Images/F4U/F4USEC.GIF)
(http://www.zenoswarbirdvideos.com/Images/P-61/P-61pwrpltchrt.gif)
(http://www.zenoswarbirdvideos.com/Images/P-47/47SEFC.gif)
My regards,
Widewing
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Originally posted by Shuckins
Widewing,
From the charts, if I may summarize a bit, it seems that most aircraft tested with 150 octane av fuel realized average gains in performance of:
Approximately 15mph in top speed. Some considerably more than this.
About 500fpm increase in rate of climb.
Is that a fair summary? Would the "official" top speeds posted by the Navy reflect the use of 130 or 150 octane fuels?
If the listed speeds were for 130 octane fuels, could we expect similar gains of 15mph and 500fpm for naval fighters such as the -5 Hellcat?
Regards, Shuckins
As far as I know, only 100/130 avgas was authorized and issued. There may have been experiments done with higher octane fuels, but aircraft in the fleet operated on 100/130, which was the standard US grade for high performance aircraft during the war.
My regards,
Widewing
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As much as it pains me to say it but you are right WW.
I should have looked at my SFC charts before typing. What I should have said was the R2800-8/10 B blocks are not rated for 115/145 grade fuel.
I stand corrected.
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Didn't see the reply for awhile and having re-read I realize I had a typo.
I had meant to say 150 PN fuel. 100/130 was standing fair in the Pacific.
-Blogs
Originally posted by Widewing
I suggest you review the specific engine charts for aircraft powered by the R2800.... All R-2800s used in US fighters were rated for 100/130 avgas. All B Block R2800s used in the F6F and F4U, as well as the P-47s were not only rated for 100/130, but had restrictions on MAP if using 100 octane fuel (typically used for transport, utility and trainers).
My regards,
Widewing
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My manual for the R2800-8, -10 arrived. Here's one tidbit.
As I suspected sustained climb rates are not assuming the engine is run at WEP. It's not even assuming rated power, but rather 75 percent of rated power, which does not include the extra horsepower from WEP.
So it's no wonder the sustained climb rates of these planes slips a bit with more weight, given that rated horsepower (not maximum HP with WEP) did not increase.
-Blogs
Sustained
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
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Good post Joe,
That's revealing. I had always assumed the published sustained climb rates were run a full power.
Or are these just figures that result from Pratt and Whitney's test programs, and not a common practice at Grumman, Chance-Vought, and the Navy?
Regards, Shuckins
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I still have a lot of this thing to read, but my understanding is that the power curves published by the engine manufacturers are specific to the engine and not the installation (e.g. F6f, F4u).
The section I was reading sounded as if the 75% rated power was an industry standard. What is interesting about that number is that it is right about where most engines are switched from auto-lean to auto-rich - in other words pouring more fuel into the cylinder to cool the charge and avoid detonation.
When you turn to specific aircraft, the question is how much power can you use in a sustained climb without overheating the engine. That will depend on the engine installation but also on the best climb speed of the plane - the best combination of climb angle and forward momentum to maximize the rate of climb. I imagine these are the numbers provided by the aircraft manufacturers or published in the standard tables from the airforce/navy we have all downloaded.
Interestingly, the best climb speed for the F6f is pretty slow (I am sure Dean has the exact number), so there isn't a great deal of cooling air getting to the cylinders, especially the bottom ones.
We've seen posts of historical materials that discuss overheating as a real problem in climbs for certain planes - the FW190 and La5 for instance.
As for instantaneous climb rates, the pilot has every available horsepower to use and I am sure WEP must really make these planes pop in a climb until the cylinder heads get too hot.
I'll post more as I get through this manual.
-Blogs
Originally posted by Shuckins
Good post Joe,
That's revealing. I had always assumed the published sustained climb rates were run a full power.
Or are these just figures that result from Pratt and Whitney's test programs, and not a common practice at Grumman, Chance-Vought, and the Navy?
Regards, Shuckins