F6F Hellcat vs. P-47 Thunderbolt (1 Viewer)

[Shortround6]

Wuzak is correct, most American fighter aircraft were designed for an 8 G service load and 12 gs ultimate for that 1.5 safety factor.
The F6F was designed for a bit more, a few other planes were designed for a bit less or, as operational weights increased, saw their safety factor shrink.

When comparing certain aircraft be sure you are comparing like to like, If the P-47s are using 150 octane fuel are the P-51s using 150 octane fuel?

 

[Dawncaster]

I looked at the load factors of the mentioned models - Mustang, Thunderbolt, Hellcat and Corsair.

Well, 12~13.5G ultimate load factors were for design weight.

P-51's 12G ultimate load factor was 8.0(limit load factor) * 1.5(3 seconds safety factor) for 8,000 lbs.

So, actual limit load factor for military condition was much lower.

If full internal load condition, P-51D's limit load factor is only 6.3G(8000 / 10135 * 8.0) and ultimate load factor is 9.45G(6.3 * 1.5)

without 85 gal - empty fuselage tank, limit loaf factor is 6.7G and ultimate load factor is 10.1G for 9625 lbs.

Only P-51H's new airframe had 7.33G limit load factor and 11G Ultimate Load factor for 9,450 lbs.

Other cases were similar, but limit load factors for navy models were based on reference weight in pilot's handbook.

According to AN 01-85FB-1 Pilot's Handbook for F6Fs, Late Hellcat showed 7.0G limit load factor and 10.5G ultimate load factor for 12,000 lbs with strengthened airframe.

So late F6F-5 with 12,740 lbs full internal load condition, limit load factor was 6.6G (12000 / 12740 * 7.0) and 9.9G (6.6 * 1.5) ultimate factor. (2 x cannons + 4 x .50 cal version with pylons)

If early Hellcat with 12,405 lbs, limit load factor is 6.8G and 10.2G ultimate. (6 x .50 cal version without pylons)

Corsair? they had 7.5G limit load factor and 11.25G ultimate load factor for 12,000 lbs.

In this case, F4U-1's the gross weight with full internal load except auxiliary wing tanks for early types, is nearly equal to 12000 lbs, so 7.5/11.25G can be applied as is. (ex. 12,028 lbs for full internal loaded F4U-1D without pylons)

for F4U-4, 7.25G (12000 / 12405 * 7.5) limit load factor and 10.9G (7.25 * 1.5) ultimate load factor for 12,405 lbs full internal load. (without pylons)

and AU-1 had 6.7G (12000 / 13343 * 7.5) limit load factor and 10.1G (6.7 * 1.5) ultimate load factor for 13343 lbs full internal load. (with pylons and rocket racks)

According to AN-01-45HB-1 Pilot's Handbook for F4U-4s, Corsair seems to be able to easily maneuver beyond the limits.

It's not surprising given the boost taps in the elevator and ailerons and great controllability of the Corsair.

....

Isn't there a lack of one model? right.

It's P-47 Thunderbolt.

Unlike the other models mentioned, I failed to find similar data for the P-47, even SAC didn't included it.

 

[AlfaKiloSierra]

Isn't there a lack of one model? right.

It's P-47 Thunderbolt.

Unlike the other models mentioned, I failed to find similar data for the P-47, even SAC didn't included it.

The P-47 had a substantially higher stall speed, and its top speed in IAS at sea level is three times the stall speed, which means it can pull 9G at sea level without stalling. If you bring it higher, the top speed in IAS drops even though that in TAS increases, and pulling more than 9G becomes more unlikely. The P-47 can certainly pull 9G while diving, but other than that, I don't see any way a P-47 will ever pull more than 9G not to mention 12G or more, as any attempt of doing so would result in accelerated stall.

Edit: The top speed may be less than 360mph depending on model, and stall speed is around 120 mph, the 361mph speed belonging to the P-47N. Therefore P-47D's before September 1944 cannot reach such a speed.

 

[tomo pauk]

...
Isn't there a lack of one model? right.

It's P-47 Thunderbolt.

Unlike the other models mentioned, I failed to find similar data for the P-47, even SAC didn't included it.

I'm unaware of the SAC doc for the P-47D.
FWIW, the 8.0 G limit is stated for the P47N @13823 lbs here, pg.3.

 

[pbehn]

The P-47 had a substantially higher stall speed, and its top speed in IAS at sea level is three times the stall speed, which means it can pull 9G at sea level without stalling.

Is that how it works? I thought stalling at maximum power on and minimum IAS were completely different properties only loosely related to each other.

 

[grampi]

The P-47 did not have tremendous firepower either. By 1943 most fighter aircraft had firepower superior to the 8 x .50cal MGs carried by the P-47.

Bigger caliber doesn't always mean superior. Most German planes were equipped with cannons, but that didn't mean they had superior firepower. The firing rate of their cannons was so slow it made it difficult for pilots to get hits on their opponents. The firing rate of the 50 cals was much higher, and they had enough punch most of the time to take out the German fighters with just a short burst...

 

[Clayton Magnet]

The firing rate of their cannons was so slow it made it difficult for pilots to get hits on their opponents. The firing rate of the 50 cals was much higher, and they had enough punch most of the time to take out the German fighters with just a short burst...

Mg 151 20mm had about the same rate of fire as an M2 .50 Cal

 

[Clayton Magnet]

Most German planes were equipped with cannons, but that didn't mean they had superior firepower.

I would say that they almost certainly did. By just about any metric you choose to calculate it

 

[Shortround6]

I would say that they almost certainly did. By just about any metric you choose to calculate it

The fw 190 did, mostly, the wing mounted MG/FFMs are a little iffy. If they are present it is no contest, if they are replaced by MG 151/20s it is definitely no contest , if they are absent with no replacement the FW 190s firepower superiority is subject to question.

The Bf 109 did not unless it had underwing guns.

 

[Clayton Magnet]

I believe the "superior firepower" claim should include, or at least consider, the total lofted weight of each installation. The M2 ranks fairly well for velocity and rate of fire, but falls short when actual destructive effect on target and installation weight are factored in. Even compared against other heavy machine guns, it is not outstanding.
But this has been discussed and debated ad nauseam, and I assume it will continue

 

[Clayton Magnet]

The Bf 109 did not unless it had underwing guns.

What about a MK 108 in the centre position? off topic, I know, sorry.
According to the authors of the link below, it had 10 times the destructive affect of a .50 cal, at about twice the weight
h ttp://www.quarryhs.co.uk/WW2guneffect.htm

 

[Shortround6]

The MK 108 was certainly destructive when it hit, the problem was hitting.

Think of an MG/FFM taken to extremes, very very destructive shell, but lousy velocity. It is not so much the trajectory but the time of flight. With a MK 108 gun you have to aim about 2 plane lengths (fighter planes) ahead of where you have to aim with a MG/FFM at 300 meters, and about 3 plane lengths (88ft?) ahead of where the MG 131 bullets will hit so they aren't much help in telling you where to shoot. A 300mph plane will move 215ft in the time it takes the MG 131 bullets to reach it at 300 meters, this assumes a high defection shot and not a stern chase.

The .50 had a high initial velocity and lost velocity slowly making it one of the easier guns to hit with. The 109 also had about 65 rounds of 30mm ammo and the gun fired at around 600rpm/10rps. You don't have much firing time. The MK 108 shells started out about 58% slower than the .50 cal bullets and at sea level lost about 15% of their velocity at 300 meters. The MK 108 loast 26% of it's velocity in the first 300 meters. Things get worse at long range but the majority of German pilots have very little business firing at an Allied fighter at over 300 meters.

 

[pinsog]

50's, especially 8 of them, were more than enough to destroy a tiny little Me109 or even a tougher FW190. If I were attacking B17's, B24's, B29's, B25's and B26's then I would want cannon. But you simply don't need 4 20mm cannon to shoot down an Me109 or even an Fw190. Good luck hitting a hard maneuvering single engine fighter with a 30mm cannon with a bowling ball trajectory.

How many rounds per gun did a 109 carry per 20mm? How many rounds per gun did a 190 carry per gun? If the 20mm have the same rate of fire as a 50 and only half the ammo per gun then your going to run out of ammo quicker. If every bullet you shot hit the target then the 20mm wins hands down, but it doesn't work that way. You miss far more than you hit. Your chasing a 109 or your chasing a P51, you shoot a 3 second burst and both planes go down if your on target whether you have 6 or 8 50's or 4 20mm. Most people are not going to shoot a half second burst and hit a hard turning fighter. How many 3 second bursts does each fighter have? If your shooting at B17, B24, B25, B26 or B29 then you need cannon, as many as you can carry.

 

[michael rauls]

Is that in the internet?

Internet???

 

[ThomasP]

Hey pinsog,

In the Air Ministry late-1930s pre-war wargames and exercises that I mentioned in a couple other posts where the comparison of various aircraft armament was being discussed, the Air Ministry figured 100 rounds of .303 cal per gun (8x Browning), 100 rounds of .50 cal/.5" (4x Browning or Vickers), 30 rounds of 20mm (presumably 2x HS404) per successful attack by the engaging fighter aircraft. A successful attack was defined as damage to the target aircraft sufficient to remove it from play (ie enough damage to neutralize or destroy the target). These numbers were considered an average for planning purposes and were arrived at via a combination of studies involving aircraft structures being shot up, in air shooting at various types of targets (via camera in air exercises, or live vs towed targets), and probability theory.

The rules for the air exercises were complicated and involved umpires both during and after the exercises, where the umpires would analyze the data and make rulings as to the validity of claims and such.

The table game rules were stylized for what I would call a grand tactical effect, ie there was no 1v1 combat maneuver simulated, only placement and allocation of groups of aircraft against other groups aircraft, with some form of number generation to predict the number and effect of engagements.

Although the post-war report did not go into detail as to how these pre-war estimates compared to war-time numbers, it did say that they were "surprisingly indicative of reality, particularly as to the effects of the German heavy cannon armament used against our heavy bombers". (The preceding quote is the best I can give from memory at the moment since I still have not been able to recover the data from my previous computer's hard drive.)


A point that I found very interesting was that, as of 1938, although the exercises and table games both indicated that most of the attacking bombers would get through the defenses to the target and drop their bombs, both methods indicated the loss rate was unsustainable. This was due to a relatively small number of bombers lost during the run in to target (no radar at the time and a low probability of intercept by fighters or shootdown by AAA) but a large number lost (primarily to fighters) while leaving the target area.

 

[P-39 Expert]

Yes, the F4U took the air intake at the wing root where it could get to the engine very easily.
View attachment 564197

Now, look at what Grumman did with the F8F.

View attachment 564198

Keep in mind the Bearcat had a single stage engine, and didn't need the intercooler plumbing and ducting. Great plane IMO, what the Thunderbolt should have been.

 

[P-39 Expert]

Hello Gentlemen. AlfaKiloSierra is new to the site so everyone should probably not use 'tongue in cheek' responses since he doesn't realize if you are teasing or not. Those of us that have been here a while know many of the respected sites we use to prove or disprove a point but he may not realize this. I just hate to see a possible new member leave the site if we are too rough on him at the beginning. All of us were new here at one time. I can't tell you how much I thought I knew that was plain wrong and how much I have learned from so many on this site.

Respectfully submitted,
Pinsog

Fubar started it.

 

[Shortround6]

Great plane IMO, what the Thunderbolt should have been

P-47 could have been what the F8F was if we rev up the good old time machine and deliver the R-2800 "C" engine to the Republic design team in 1940, and build the factory to make the R-2800 "C" (it used a few techniques that did not exist in 1940) AND if we deliver large quantities of 115/145 fuel to run the R-2800C engine on instead of the 100/100 the 1940 R-2800 was designed to run on.
Time machine is going to need an overhaul after all those runs.

 

[P-39 Expert]

So there weren't any single stage R-2800s available in 1941/42? Mainly what the Thunderbolt needed was to weigh 10000# like the Bearcat instead of 13500#.

 

[Kevin J]

So there weren't any single stage R-2800s available in 1941/42? Mainly what the Thunderbolt needed was to weigh 10000# like the Bearcat instead of 13500#.

Okay, let's put a single stage R-2800 into a P-43 in 1940 and rip out the turbo. That should give us a low level hotrod to defeat the enemy everywhere, although maybe only the Russians would take it.