F4U Corsair vs P-51 Mustang
- Thread starter Catch22
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Shortround6
Lieutenant General
Think you could come up with source for that???????
B-29 weights were all over the place, 7200lbs was a drop in the bucket. A B-29 that took off at 100,000lbs weight could use 800 gallons of fuel (4800lbs) just climbing to 28,000ft, taking off at 140,000lbs 800 gallons won't even get you to 15,000ft. Empty weight of a standard B-29 was 74,500lbs and noraml gross was 120,000lbs. without knowing the actual weight of both planes involved this story is pretty much useless.
The advantage the P-47 had at 25,000ft and up was that it's engine was still making full power (in some models to over 30,000ft) which meant it could sustain a turn better than many other aircraft. Please remember that at 30,000ft the air is about 37% as dense as it is at sea level so even level fight stall speeds are higher than sea level. Now try banking at over 60 degrees (really like to see B-29 doing over a 60% degree bank at 30,000ft) and pulling 4 or more "G"s.
Granted the B-29 had turbos but most US bombers were never intended to pull more than 3.8 "G"s and if loaded heavily were rated a lot closer to 2 "G"s
This is at least one source for the turning circle thing... Wendover's Atomic Secret | Military Aviation | Air & Space Magazine
(then) Colonel Tibbets had claimed the plane's weight was 7200 pounds lighter than a traditional B-29: Weight figures seemed based around the Silverplate carrying around a 10,000 pound bomb (Fat Man: 10300; Littleboy: 8900).
60-degrees of bank correlates to 2g...
Does it? How does that work?
Shortround6
Lieutenant General
I would certainly like to see something a bit more detailed than that. You do realize that P-47D-25 had a wing loading of about 48lbs per square ft when FULLY loaded clean( 370 gallons of fuel, extra oil, 425 rounds per gun). While a B-29 even with 7000lbs stripped out of it is going to weigh 64,500lbs empty. Standard empty weight is 71,500lbs for the early ones. Wing loading is 37.2lbs except you have no crew, no oil, no guns even in the tail, no oxygen and maybe not even radios. Basic weight of a standard B-29 was 74,050 lbs so 7000lbs from that is 67,000lbs or wing loading of 38.9lbs/sq/ft. Now if we add just 17,000lbs of fuel (2840 gallons out of the the max internal 6803 gallons not including bombbay tanks) we get a plane weight of 84,000lbs and a wing loading of.....................48.8lbs/sq/ft. Please note there are no bombs on board. Also note the P-47 will be hundreds of pounds lighter by the time it climbs to 34,000ft.
Yes there are other things beside wing loading that affect lift and turning ability, but this story is not looking good. A lightly loaded B-29 may be able to out turn a fully loaded but clean P-47 but it seems to depend an awful lot on the weight of the two planes.
As would I...
Is this with the center tank loaded?
I figured one would assume the following
- B-29 with fuel load used for a high altitude flight to Hiroshima & Nagasaki with the specified crew, and 8,900 to 10,300 pound payload, minus 7200 pounds due to the removal of turrets, guns, and ammunition
- Fuel status of P-47 would be either shortly after reaching altitude and/or normal combat weight with with or without the center tank filled.
Just search for level-flight g-load bank angle
Bank Angle Vs. G Force - Aviation Safety Article
Flying Lessons
KiwiBiggles
Senior Airman
In level flight, in a balanced turn the G loading is the the reciprocal of the cosine of the bank angle (or the secant, if you prefer).
Shortround6
Lieutenant General
What center tank? The weight given was for the internal tanks, which on a late model P-47 was enlarged to hold 370 gallons instead of the 305 gallons of the early version
Please do some of your own research, I gave you some numbers which can be checked by either the flight manual available in the tech section of this site or by using the SAC sheets available at Standard Aircraft Characteristics Arcive
I would note that the "combat" weight of a normal B-29 was given as 101,250lbs at which point the plane had a load factor of 3.10. 'Combat' weight is after a fair amount of fuel is burned off and bombs dropped. For instance a plane that took off at 140,000lbs with 10,000lbs of bombs and 47,196lbs of fuel has a "combat" weight of 101,250lbs. That 47,196lb of fuel includes bomb bay tanks. Now to get down to the combat weight you need to drop/use 38,750lbs worth of bombs, fuel, oil and the bomb bay tanks. Keeping the bombs (even it it was possible) while dropping the bomb bay tanks means you don't have an awful lot of fuel to get home. Only about 1/4 of the fuel you took off with, so I am guessing combat weight doesn't included bombs.
The Silverplate aircraft will be a little lighter but enough to really out maneuver a P-47?
Japanese aircraft didn't have turbos and were rather limited in maneuverability at high altitudes. Even if they could reach a high speed in straight and level flight any maneuvering is going to kill speed and they don't have enough engine power to compensate. A B-29 running light (100,000lbs or so) could climb at over 500fpm at 34,000ft easily giving it a power reserve it could use to turn without losing altitude.
GregP
Major
g = 1 /cosine (bank angle). We have been over this many times, and it holds true only in a level turn. A 3-g turn is about a 70° bank. (2.92 or so anyway).
There was never a B-29 that could out-turn a P-47 made but, at 35,000 feet, it MIGHT be. Let's see. At high altitude, span loading gives a pretty good general indication of turning ability.
The Republic P-47D that took off at a max normal weight of 14,500 pounds has a span loading of 355 lbs/ft.
A Boeing B-29 that took off at a max normal weight of 137,959 lbs has a span loading of 977 lbs/ft.
Looks like the P-47 will turn a LOT better than a B-29, some 3 times better, and removing 7,000 or even 14,000 lbs will NOT change it much. Even if the B-29 is at 100,000 lbs, the span loading is 708 lbs/ft. The B-29 wing is always much more heavily loaded, as we'd expect, than a P-47 wing.
Incidentally, at 35,000 feet, a P-47D was THE best or one of the best fighters of the entire war. Any P-47 pilot wanted to fight way up high where he held all the cards. But, since it was hard to find targets up there after the bombers started bombing lower, he usually had to come down a bit to fight.
There was never a B-29 that could out-turn a P-47 made but, at 35,000 feet, it MIGHT be. Let's see. At high altitude, span loading gives a pretty good general indication of turning ability.
The Republic P-47D that took off at a max normal weight of 14,500 pounds has a span loading of 355 lbs/ft.
A Boeing B-29 that took off at a max normal weight of 137,959 lbs has a span loading of 977 lbs/ft.
Looks like the P-47 will turn a LOT better than a B-29, some 3 times better, and removing 7,000 or even 14,000 lbs will NOT change it much. Even if the B-29 is at 100,000 lbs, the span loading is 708 lbs/ft. The B-29 wing is always much more heavily loaded, as we'd expect, than a P-47 wing.
Incidentally, at 35,000 feet, a P-47D was THE best or one of the best fighters of the entire war. Any P-47 pilot wanted to fight way up high where he held all the cards. But, since it was hard to find targets up there after the bombers started bombing lower, he usually had to come down a bit to fight.
I thought the P-47's had tanks in the wings, then as time went on a ferry tank was replaced with a drop tank, then wing & centerline drop-tanks
65 more gallons regardless of tank configuration sounds okay enough
But with 7200 pounds of turrets, guns, ammo, and other stuff removed would be down to 94050, and takeoff would be 132800 lbs
I don't know, I'm just going on what I was told..
I never had the formula before, but I really like it... I can actually do the computations on my own...
drgondog
Major
Would be great to research before operating on "I thought" in these debates?
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Bill - internal wing tanks were installed on the P-47N only.
drgondog
Major
I know Tomo - just a typo. It was an entirely new wing.
All new wing? Care to elaborate?.
Shortround6
Lieutenant General
Maybe not ALL new but........
They had to do something to the wing roots to fit the fuel tanks
They had to do something to the wing roots to fit the fuel tanks
Okay, I know what I'm looking at, the rear tank of the two was the one I thought was the 'center tank'.[/quote]
drgondog
Major
Thanks for the plan view SR. Entirely new is an overstatement as many parts are interchangeable. That said the wing is not interchangeable and the N wing had its main spars and carry through structure modified to take the increased stresses applied in pull out for a.) extra internal fuel and b.) moving the CG of outboard pylon span ward. The latter increased the bending and torsion loads imposed by longer moment arm on fuel tanks and bombs.
Shortround6
Lieutenant General
Heck, just moving the .50 cal guns and ammo is going to change the bending moment. And you can't drop those
swampyankee
Chief Master Sergeant
- 4,308
- Jun 25, 2013
According to Joe Baugher, the P-47N had a new wing (Republic P-47N Thunderbolt)
