Corsair and Hellcat in Europe

Shortround6 said:

Correct, but that is the speed for a single aircraft.
Now put 3 dozen in formation, fly at 220mph and then have the formation do a 45 degree turn. Guys on the inside have no trouble. They throttle back to 210 or 200 or 195 or whatever they have to do to keep station as the rest of the formation flys a bigger arc to the make the turn.
It is the guys on the outside of the turn that have trouble,if using the power setting for 230mph doesn't allow them to keep station they have to advance the throttles into the rich mixture position and suck down a lot more fuel per minute. Not a big deal for one or two turns but combined with throttle jockeying that goes on with trying to keep a large formation together in close proximity and ranges/speeds take beating compared to single aircraft performance.

Formation speed is governed by the worst performing plane in the group being in the worst position. Any other planning leads to stragglers which become losses.

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Totally agree and without any personal knowledge would expect it to average it out at approx. 170mph with 190mph as a max. What the numbers d show is a cruise of 220 is a pipe dream.

Glider said:

Totally agree and without any personal knowledge would expect it to average it out at approx. 170mph with 190mph as a max. What the numbers d show is a cruise of 220 is a pipe dream.

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Gentlemen,
I dug out one of the very first books I purchased back during the age of dinosaurs. It is titled "Flying Fortress" by Edward Jablonski. On page 239 there is a photo of a 15th Air Force mission planning map. The map gives compass headings, distance, and time. The bomb group was the 463rd.. The target was Blechhammer. The date, Dec 12, 1944
Leg Heading Distance (Miles) Time (minutes) Speed mph (calculated rounded)
Outbound 25 degrees 263 77 205
Outbound 22 degrees 81 21 231
Outbound 332 degrees 111 33 202
Outbound 313 degrees 48 15 192
IP 348 degrees 42 11 229
Target 72 degrees 41 8 308
Home 147 degrees 122 33 222
Home 170 degrees 118 36 197
Home 221 degrees 92 34 162
Home 205 degrees 263 96 164

The different outbound legs were plotted to avoid known Flak concentrations. The homeward legs did the same. I speculate that the slower speeds away from the target were to allow damaged bombers to stay in formation, or it could be the effects of a headwind. Blechhammer was an "oil target" so flak would have been heavy. I was surprised to see the speed of the bombers as they bombed the target.

Adding the times and miles together I get 1181 miles round trip and 6 hours and 4 minutes.

My uncle who flew with the 483rd made 4 trips to Blechhammer (8/27, 9/13, 10/14, 10/17 in 44) and his diary shows flight times of 7 hrs 25 min, 7 hrs 40 min, 8 hrs 20 min, and 8 hrs 30 min. I believe his diary shows the total air time to include take-off, assembly, and landing. I am guessing the planning map shows actual flight times from after assembly to arrival over base to land.

Note that the speeds I calculated are ground speeds, not true or indicated. I suspect the formation would fly at whatever IAS to get the desired ground speed (jf possible) I do not know if the courses and times include adjustments for wind. Also note that the bombers did not fly one speed the entiree mission, nor did they fly a straight line to the target and back.
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For informatiom

Eagledad

Course changes are one aspect to put downward pressure on point to point mission times. however, the main variables are fuel loads, max overload weights, raid sizes, form up times, airfield spot rates (how quickly the aircraft can be gotten airborne) and overwhelmingly the headwinds. Weather states are by far the hardest to predict in mission planning.

Escort fighhters will have variable minimum speed and endurance requirements, and it will always be the case that the escorts need to have significantly higher cruising speed than the bombers. The escorts typically will be vectored to meet the bomber formation enroute, then perform a variable position, moving forward, above and beside the bombers to maximise their cover effects. Fighters usually do not provide continuous cover from start to finish, they run shuttles, out to a certain distance, whereupon they turn for home and are relieved by another replacement escort force. That meant the escorts were burning fuel reserves more quickly than these simple range comparisons are suggesting.

The effective combat range of the hellcat over japan in 1945 was between 230 and 250 miles depending on the mission. Corsair was about the same. seafire was about 175 miles. Zeroes had an effective combat range of about 400miles . ive read theMustang II had an effective combat range9radius) of just over 500 miles, that might be wrong.

P-39s did not thave the same legs as these aircraft, pure and simple. They had a hard time flying from Moresby to gona, a distance of just over 100 miles. Sure you will get variations for different subtypes, but not to the extent of several hundred miles......

Just to add some context to Eagledad's post, here is the Blechhammer South Plant (the target of the Dec 12th raid) as it appeared in a recon photo from May '44:


Source: Bierawka; Opole Province; Poland | NCAP - National Collection of Aerial Photography

The 303BG website gives mission times.

example: http://www.303rdbg.com/missionreports/119.pdf

parsifal said:

The effective combat range of the hellcat over japan in 1945 was between 230 and 250 miles depending on the mission. Corsair was about the same. seafire was about 175 miles. Zeroes had an effective combat range of about 400miles . ive read theMustang II had an effective combat range9radius) of just over 500 miles, that might be wrong.

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Great post as usual. I assume that these ranges are on internal fuel only, right? I ask this because US Navy pilots would be using their standard "Problem F-1" to determine radius of action. NAVAER documents state that an F6F-5 with 150 gallon drop tank had a combat radius anywhere from 391-431 statute miles; the F4U-1D with the same external fuel load (but slightly less internal) had a combat radius of just around 380 statute miles. This makes sense to me because with 60% more fuel they could theoretically fly about 60% further. If we place them in an ETO environment this range would of course drop some due to the necessity to fly higher altitudes and at greater speeds.

DarrenW said:

The P-47D had an escort radius of roughly 375 miles with 413 gallons of fuel, achieving an average of roughly 1.8 mpg. If we use this as a constant for the other two fighters in question, the F6F-3/5 (400 gallons total) would have a theoretical escort range of 360 miles, the F4U-1D (387 gallons total) conceivably 348 miles. With additional internal fuel the P-47D could fly an escort radius of 430 miles. Add in the fact that the Thunderbolt was out-fitted with progressively lager belly/ external wing tanks and it's easy to see that the notion of the Hellcat and Corsair flying high altitude escort in Europe as well or better then the Army fighter just doesn't hold water.

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Itis not just the fuel, the P-47 may have had lower drag and the P-47's engine was more fuel efficient at high altitude cruise due to the turbo.

Gentlemen,
Dean, in America's Hundred Thousand (page 113) gives the P-47 a zero lift drag coefficient (Cdo) of .0213 and a flat plate area of 6.39 square feet.
The data for the F4U is Cdo =.0267, flat plate area 8.38
The data for the F6F is Cdo = .0272, flat plate area 9.08

This would suggest that the P-47 is a less "draggy" aircraft than the F4U or the F6F

Eagledad

Flat Plate Area = Cdo X Wing area

Thank you.

Unfortunately that doesn't seem to line up well with the speeds the planes could do at sea level using 2000hp ( no water injection or turbo boost).

Hellcats seem to do about 310-320mph at sea level using 52.5in boost while the P-47 seems to do about 335mph using 52in of boost?

Certainly welcome to correction on this. I would note that the P-47 did use a thinner wing which might give it an advantage at high speed?

SR

But it does, sort of. I would expect the P-47 to be faster than the F6F and F4U. As you wrote, P-47 335. F6F 310-320.
However, in looking at William's site, the F4U is rated at approximately 350 at sea level using 2000 hp.
I have seen a navy document that shows production F4U-1s have a sea level speed of 339.
Bottom line, it appears that the F4U with the same power as the P-47 is faster.

I did write that the flat plate areas suggested that the P-47 is less "draggy", but the does not appear to be true in all cases.

Any aeronautical engineers care to help me out?

Eagledad

When I get home I can find the page in Dean's book where he quotes a CDo of .025 for the P-47D.

.... I will also try to clarify my "theory" about range and provide different drag figures for the three fighters because it's pretty apparent that they vary heavily depending on source.

I'm not sure about that S/L speed of the P-47 in military power. I have seen many documents where it was very close to the F6F in a similar configuration.

It does look like the P-47 has an edge in aerodynamic cleanliness (thinner air foil design = less induced drag), which is amplified as altitude increases and the turbo really starts to really kick in.

tomo pauk said:

The US duo, in 1943, has a number of advantages, as well as disadvantages, to be deployed in Europe.
In the ETO, at altitudes from 20-30000 ft, they offer no speed advantage over German fighters (they might easily be in disadvantage on any altitude), and at any altitude the Germans should climb faster.
The fuel situation is, interesting, to say at least. The F4U historically did not carried drop tanks until late 1943, using the wing tanks instead. 361 USG should give about equal range, on the 1st sight, as the 370 USG found at late P-47Ds; both planes flying at ~25000 ft. That makes some 300 miles max, ie. not some long short range fighter.
The F6F-3 carried the drop tank from the day one (corrections welcomed), fuel quantity being 250 USG internal + 150 USG external. We might compare that with the late 1943 P-47 situation in ETO (305 + 108 USG). The map I've posted twice on the forum gives 375 miles of combat radius for such P-47, the F6F might not venture so deep in the Continent because of less internal fuel - 350 might be the maximum?

Deployed in the MTO, they might opt for lower cruising altitudes in order to get better mileage. The Italo-German opposition there should be less capable on aggregate.

There is another thing to consider - the LW in ETO was fielding not so big number of fighters (300-350? corrections?); an early and wholesale (500 fighters?) introduction of a 300-350 mile fighter might deliver quite a few bloody nose for the LW, before they get smart and relocate the interceptions out of the escorts' radius?

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Some more "fuel" for discussion here; http://www.wwiiaircraftperformance.org/f4u/p-51b-f4u-1-navycomp.pdf

Eric Brown's innovative book "Duels in the Sky" posited some interesting matchups based on his experience with each (all!) types. I know he addressed F4U v 190 but do not recall the verdict. Am reminded of Robin Olds' statement when asked which was better: 51 or 190. He said "It depended on the pilot, and I never fought a 190 pilot who was as good as I was." (Pause) "But I fought a better one once and I was lucky to get away!"

Vought designed the F4U as a relatively low-production machine, never expecting it would go 12k copies. I cannot find my notes (of course) but Rex Beisel stressed that Vought aerodynamics shop sought minimum drag and max power. (Odd how few folks realize the F4U was America's first single-engine production a/c to make 400 mph.) Everybody cites the inverted gull wing as permitting a short(er) landing gear but in fact it gave an aerodynamic advantage by mating the wing stub to the fuselage at that angle.

The oft-cited but little-referenced 1944 joint fighter conference asked participants the best fighter & fighter-bomber in various categories. Corky was involved and so was Rex Barber. Rex said (and I quoted him in my Naval Institute book) that if the allies had to build one fighter, it shoulda been the Corsair.

There was also the humongous prop to consider Barrett.

Ok, I looked at AHT by Dean and found that the profile drag given for the P-47D in table 98 on page 598 is .0251. I also noticed that the figure of .0213 is listed for the P-47B, not D (probably different source data used by author). There's another wartime source (by Vought) that shows profile drag for the P-47D, F4U-1D, and F6F-5 as .022, .020, and .023 respectively. Very close indeed. I'm fairly certain that Dean used the drag figures found in NACA report L5A30, which gave wind tunnel results for many aircraft including the F6F-3 and F4U-1, but not the P-47 unfortunately (I found the document listed in his references). The NACA report gives total drag (CD), and when you subtract induced drag (CDi) from what's given you get a number very close to what's presented in his book (CDo).

As most people with just an elementary understanding of aerodynamics probably know, these numbers are highly dependent on the testing environment as well as the condition (or state) of the aircraft under test. Without having these three aircraft side-by-side and tested under the exact same conditions one cannot truly say with any degree of certainty that aircraft A is "more draggy" than aircraft "B".

I will say though that the P-47 is definitely blessed with a "speedier" airfoil than either of the two Navy fighters, and due to this fact I would personally give it an ever so slight edge in overall aerodynamic cleanliness. However, there are other parameters that also effect drag, but to a lesser degree than wing design (the thrust angle of the airfoil and fuselage surface refinement being just a couple of them).

DarrenW said:

Ok, I looked at AHT by Dean and found that the profile drag given for the P-47D in table 98 on page 598 is .0251. I also noticed that the figure of .0213 is listed for the P-47B, not D (probably different source data used by author). There's another wartime source (by Vought) that shows profile drag for the P-47D, F4U-1D, and F6F-5 as .022, .020, and .023 respectively. Very close indeed. I'm fairly certain that Dean used the drag figures found in NACA report L5A30, which gave wind tunnel results for many aircraft including the F6F-3 and F4U-1, but not the P-47 unfortunately (I found the document listed in his references). The NACA report gives total drag (CD), and when you subtract induced drag (CDi) from what's given you get a number very close to what's presented in his book (CDo).

As most people with just an elementary understanding of aerodynamics probably know, these numbers are highly dependent on the testing environment as well as the condition (or state) of the aircraft under test. Without having these three aircraft side-by-side and tested under the exact same conditions one cannot truly say with any degree of certainty that aircraft A is "more draggy" than aircraft "B".

I will say though that the P-47 is definitely blessed with a "speedier" airfoil than either of the two Navy fighters, and due to this fact I would personally give it an ever so slight edge in overall aerodynamic cleanliness. However, there are other parameters that also effect drag, but to a lesser degree than wing design (the thrust angle of the airfoil and fuselage surface refinement being just a couple of them).

I'm so far not convinced that there is enough of a difference in profile drag between these three fighters to effect the outcome of a 400 mile trip. I believe fuel carrying ability (especially internal) is the biggest determinant here.

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I would tend to be careful of differences in zero-lift drag coefficient of less than about 5% even if done by the same group using data from the same wind tunnels or series of tests.


Here, the Hellcat has both the largest wing area and greatest Cd0, which is consistent with it being the slowest of the three.

DarrenW said:

I'm not sure about that S/L speed of the P-47 in military power. I have seen many documents where it was very close to the F6F in a similar configuration.

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I looked at the spread sheet that I created a little while back, where I closely examined the flight test data of the Hellcat, Thunderbolt, and Corsair on wwiiaircraftperformance. I tried to find specifications at similar altitudes and horsepower (not necessarily manifold pressures), being careful to note the configuration of the aircraft during the particular test. What I found was that there's limited data for the Thunderbolt below 5,000 feet, and when S/L speed was given it was usually during ADI testing.

From what I can tell, with roughly 2000 HP available the speed of the F6F-3 indeed averaged 320mph at S/L (one aircraft carried wing pylons). The F4U-1 was much faster under the same power, achieving on average 345 mph (no mention of pylons for any of the test aircraft). The Thunderbolt was harder to figure out, due to the minimal amount of data at sea level height. At this same engine output I was only able to find a figure for a particular P-47D of 303 mph, and a P-47N that flew at 327 mph. Both of these aircraft had wing pylons. Not sure why such a huge difference in speeds between the two Thunderbolt models being flown under basically the same horsepower. One thing I did notice was that there wasn't any test data for the P-47 which stipulated speeds even close to 335 mph at S/L without the use of water injection.

It was also interesting to look at the various speeds with roughly 2200 HP available (using ADI). A P-47D was clocked at 330 mph, while a F6F-3 flew at 334 mph and a F4U-1 at 364 mph. All aircraft were without wing pylons during these particular tests.

It does look like the Corsair was hands down the fastest of the three at sea level. Maybe Vought's profile drag numbers are the most correct after all????