This Should Have Gone into Production...

[Widewing]

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

[Shuckins]

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

[joeblogs]

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

[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.

[Widewing]

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

[F4UDOA]

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

[bkbandit]

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 ).

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.

[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

[Widewing]

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

My regards,

Widewing

[joeblogs]

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

[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

[joeblogs]

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

[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?

[joeblogs]

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?

[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.