P-47N Thunderbolt vs. F4U-4 Corsair - Which was superior?

[plan_D]

You had to remind me it was near christmas, didn't you? All I get when going into town is the decorations flashing in my face, and the town clock playing jingle bells on the hour. And then everyone thinks I'm weird because I don't "celebrate" christmas.

Sorry ...carry on with your little plane talk, I'll just mutter in disgust ...in that corner, over there.

 

[DerAdlerIstGelandet]

I am not sure that anyone here sees what you are doing as a vendetta, it has been interesting reading. I am just telling people to stop getting personal about it.

 

[gabbys]

I am new to this board, so don't know if this was posted.

I did a quick scan of the thread but didn't see this posted.

This is the Curtis dive testing data for a highly modified P-47.

As to which is the better plane, it depends on where the fight is.

above 25K P-47, below 25K, I would take the F4U-4

From: http://home.att.net/~historyzone/Fisher.html

The desire to develop a propeller that maintained its efficiency at transonic speeds led the Curtiss Propeller Division to design and test several different concepts. Herb Fisher was the logical choice to fly the test aircraft. Curtiss was able to obtain a P-47D-30-RE from the Air Corps. Fitted with one of several different "supersonic" propellers, Fisher undertook a long and risky flight test program that incorporated high Mach dives from high altitudes. Typically, Fisher would climb above 35,000 ft. He would then push over into a steep dive, allowing his airspeed to build beyond 560 mph (true airspeed). He would then execute a pullout at 18,000 ft. Several of these dives resulted in speeds of Mach .83. However, that was as fast as the P-47 could go.

Despite having a propeller that was designed to be more efficient at these speeds, the fact remained that the drag rise across the prop was so great that it functioned like a giant disk shaped air brake. Fisher had proved beyond any doubt that all previous claims of exceeding the speed of sound while diving a prop driven aircraft were untrue. There is little doubt that the pilots who reported speeds in excess of Mach 1 were honestly and accurately reporting what they has seen on their air speed indicator. However, due to the extreme rate of descent, the pressure differential in the static pressure airspeed indicator lags far behind the actual altitude of the aircraft. Air speed indicators of the era were not designed to cope with descents that could exceed 40,000 feet per minute. This difference between outside pressure and that within the system would indicate wildly ambitious speeds. These pilots had simply been fooled. When we stop and consider that the ultra-sleek P-80A Shooting Star jet fighter was never able to exceed Mach .94, how can anyone believe that a prop driven fighter could even come close?

 

[syscom3]

Great Find!!!!!!!!!!!!!!!

 

[Gnomey]

Good post gabbys, welcome to the forum.

 

[DerAdlerIstGelandet]

Welcome to the site, good post.

 

[JonJGoldberg]

Reply to gabbys >>>

Welcome. Good post. I read the article, find it quite interesting that Curtiss was still using the '47 in 1949 as a test bed for props. That's later than I thought that they would still play with props.

Reply to all >>>
A very interesting happened last night... Some background: I had been exchanging E-mails Wmaxt; we were discussing the P-47s ammo count on my tables, which Wmaxt felt to be high by 1/3rd. I sent him an illustration of my point, he replied saying the info I had was in error, that I should visit a web-site referred in his E-mail. I did just that will post my reply in a moment. As a side note, Wmaxt today sent me an E-mail saying that he was an enthusiast, not an expert. I'd like to say to all, I'm no expert either, I've probably have taken this a bit too far. Compulsion, my compulsion, forces this, I apologize in advance, thank you for your tolerance. Ultimately, I hope you all find his as revealing as I did...

As taken from a reply to Wmaxt: Subj: Re: WWII Gun Page
Date: 11/29/2005 8:47:19 PM Eastern Standard Time

Thanks Bill but the site I used for my tables, that I reference, http://www.quarry.nildram.co.uk/index.htm, uses the same authors, Williams Gusting; instead of being updated in 1998, It was updated mid to end of 2004.

Now I visited your site anyway, would like to thank you as some (about 1/3 to 1/2) of the old links still worked; at the same time, I need to reconsider things: A great deal of informational links took me to the J Baugher sites, that I referenced, that you said were incorrect; further you told me you had researched this. (I did receive your E-mail about being an enthusiast) I've got to say that I've greatly appreciate all of your moral support, what I hope are 'Nobel' intentions; as opposed to others that have stated they have the books that would contain what appears below. In belief of this I share the picture (I found though your old Gun Table article; I didn't find your pic, found one on the '51, not posted) below.

Please take notice on the Ammo, Max is 3400 rounds, or 425 per gun, my stat on the D, not the N (my opinion is that this paper was drafted before the N was a thought, I believe it was written sometime around when the 47-D-11 through 47-D-23 were in production, with the 'universal' wing). Now you may interpret that I'm off by 50 rounds, but I think not. Closer inspection reveals that the 400 RPG is limit used only within the Special Combat column. What I Joe B were saying, is that when the wing was loaded at capacity, by drop tank, or bomb, each gun was limited to 267 RPG on the N, seems that there was a 200 RPG limit on the Ds. This is proven in this document (1200 rounds = 360 lbs plus 400 rounds = 120 lbs for the other two guns). The Special Combat column contains a weight addition for oil, required for extended range flights, but no specified aux tank/s, gas, or bomb, contains what is in my opinion, the 36.5 lb shackle installed on the pylons (I've no idea what the 5 lbs is for in the Max Fuel coulomb, conclude that the additional 30 lbs found in the Normal Combat column is for the 15 lb 3-tube rocket mount used at the time I believe this was written, fuel could not be applied to the pylon with this shackle, hence no additional oil). Of further interest are the gross weights in the Special Combat, Max Load column (there is a math error in the Max Load column, it should say 15100 lbs, plays a big part here). There is an 1800 lb difference between the two (actually). So the ' 47 could not carry both full ammo a full belly hard point, support at the same time wing ordinance [to 13300lbs add 540 lbs of bullets, 1333 lbs of fuel the weight of the belly tank, we are 73 pounds over weight before we add bombs, shackles).

On my tables, combat weight (D) is 13752 lbs; using this paper I should be at 13695 lbs (full internal fuel full ammo, no external ordinance), a 57 lb differance. How much does the IFF box Sal brought up Joe B confirms weigh? Its missing from the below weight table. My numbers, at lest from this hapenstance, are pretty darn close.... Too close to argue.

 

[JonJGoldberg]

To all of my 'P-47N vs. F4U-4' friends >>>

No postings in such a long time; what happened? This very active thread is dead? No; its not… Let's see if we can't find something to talk about…

I'd like to envision the contestants entering a 10 mile radius 'Arena' at a height, speed, course time designated by 'sponsoring' committee. After that time, until there is a victor, leaving the 20 mile cylinder is grounds for dismissal/forfeiture. The aircraft are fueled armed, as defined before, to their own individual "combat weight", as their flight manuals dictate. The 'sponsoring' committee may decide to deduct proportionately from each: For example, both are to be at 50% fuel ammo from "combat weight". The contestants should take off from the same field; at the same time, allowed 15 or 20 minutes after their simultaneous arrival; one forced to cover, at any height they feel opportunity best, 25% of the circumference of the arena traveling, as decided by coin toss, clockwise, the other counter clockwise. Upon reaching the mark, they may go anywhere, as they feel opportunity best; remaining outside the arena until the designated "combat" time, at which point they need to be inside the arena within 5 seconds; not to exit unless the victor has been decided, or choosing to be the looser.

In the above P-47N vs. F4U-4 contest I choose the N.

If the question, P-47N vs. F4U-4: Which was superior; is meant to imply, in which would you (I) choose to serve? Historically, that's a tuff one. If service is limited to WW2, the goal is to 'have fun', I choose the N. If service is limited to WW2, the goal is to survive, I choose the -4.

If the question is meant to imply, which looks better I choose, today, maybe not in a few months, the 47, but my I choose a late production Razor-Back please… I promise the runner up may be an F4U-1D.

In the above I've chosen the '47, 3 out of 4 times. What were your scores?

 

[Jank]

If you read back through the thread a bit, it was generally agreed that below 30,000 feet the Corsar would take honors and above 30,000 feet the thunderbolt would come out on top.

 

[JonJGoldberg]

Reply to Jank >>>

...So the question remains, do I force you to my advantage or do you force me to yours?

The '47N is armed with speed, unless I let you drag me too low; no I think '47, would be able to force you high...

 

[wmaxt]

Reply to Jank >>>

...So the question remains, do I force you to my advantage or do you force me to yours?

The '47N is armed with speed, unless I let you drag me too low; no I think '47, would be able to force you high...

Agreed, but how can the N keep the fight above 25k, the F4U-4 vrs. P-47N dive capabilities are so close?

If the initial attack fails or is countered the fight will go lower and slower. If a N catches a Corsair above 20/25k his tactic will be to slash and climb using it's capabilities to their max (height and top speed). At altitude the turbo keeps the energy level high in the P-47 giving it the advantage.

The Corsair will dive because below 20k the N model that doesn't use the boom and zoom is going to be in real trouble very quickly. The F4U-4 can out fight it in any situation except dive and thats close enough that it isn't a clean escape for the P-47.

wmaxt

 

[JonJGoldberg]

Reply To Wmaxt >>>
As you dive I will pursue, not follow, from above... I will watch take my next opportunity.

Everything in the air that is beneath me, especially if it is a one-seater . . . is lost, for it cannot shoot to the rear.

— Baron Manfred von Richthofen

 

[Monkeysee1]

A word on critical mach.

Critical Mach is not a limiting factor for aircraft. Critical mach is the airspeed or mach number at which airflow over the wings begins going supersonic. Along with this supersonic flow, some of that air begins detaching from the wings. While this ups the amount of drag on the wing significantly it does not limit the continued acceleration of that wing or aircraft.
What does limit an aircraft's speed is as the velocity continues to increase that area where the airflow is supersonic and thus disturbed moves back onto the control surfaces causing them to vibrate, catch, and grab (if you don't have hydraulic controls). While usually this won't make a plane uncontrollable it does make it unsteady and a handful to hang onto.
Compressability is where the sonic wave caused by the wing blocks airflow onto the elevator thus making either immovable or ineffectual as a control surface.
Critical Mach is not a limiting factor for aircraft, the MMO (max mach operate number) is usually a few more points up on the scale. All critical mach tells you about is what point are you going to burn more fuel keeping that wing supersonic, and an idea of how 'fast' a wing do you have. It isn't limiting though.

 

[JonJGoldberg]

Reply to Monkeysee1 >>>
I am not a pilot, nor am I an expert... My view:

The design flight envelope is not the cruise-to-stall ratio nor is it the range of airspeed between minimum maximum, rather the flight envelope of an aircraft be stated as "the parameters within which an aircraft can be safely operated, with average pilot ability, at varying density altitudes, airframe states, wing loadings and atmospheric turbulence". Airframe states refer to CG, 'nose angle', flap extensions, undercarriage fuel tank position their weights. It is a dynamic three dimensional model which has airspeed along one axis, wing loading or 'g' along the second density altitude along the third; there are separate flight envelopes for each airframe state. These parameters usually are the limiting critical airspeeds – Va, Vne, Vno, Vs1 and Vso; the certificated load limits possibly an angle of bank limitation.

Vne – never exceed speed. The IAS which should never be intentionally exceeded in a dive or other maneuver – in smooth air; usually 90% of Vd, the 'design diving speed'.

The Army Navy posted numbers differently (for that matter everyone has their own slant, that's why I defined mine above). I recently purchased the 'pilots manuals' (scanned reprints) for the '47D, F4U-1 (I do not have nor can I find, as of yet, manuals for the N -4) within in them the AAF simply states that the dive 'recovery' speed 'limit' is 500 mph, at 12000 ft then goes on to describe individual speed, height other limits. The Navy/Marine pilot is forced to view two tables (Angle of Attack at Terminal Velocity vs. Dive Angle Angle of Attack vs. Airspeed Indicator), cross reference them for an answer, a more 'exact' answer to be sure, but time consuming. Realizing this, compounding it with 'British' specs, German specs, I converted these numbers to a 'universally' understood accepted, identification method for the various airspeeds at which an aircraft may be operated.

I calculated Vne ('Clean' at posted 'Combat Weight') to be 443 mph for the Corsair -4. (1st pass extrapolations from the F4U-1 book's charts put this number at 426.2 mph, but this seems way low to me, my original number seems low... anyway).

Know and use all the capabilities in your airplane. If you don't, sooner or later, some guy who does use them all will kick your ass.
—Dave 'Preacher' Pace, USN

I calculated Vne ('Clean' at posted 'Combat Weight') to be 505 mph for the Super-Bolt. (1st pass extrapolations from the '47D book's put this number at 500 mph).

Beware the lessons of a fighter pilot who would rather fly a slide rule than kick your ass!
—Commander Ron 'Mugs' McKeown, USN

My Corsair foe might have had a cruel surprise had you not forced my exposure.

 

[syscom3]

John, didnt the Thunderbolt have some excellent roll effects from the torque effect of that powerfull engine and huge prop?

 

[DerAdlerIstGelandet]

Wow you really get into this, I have to say. Good postings though Jon. I may not respong much in this thread, but I enjoy reading it.

 

[pbfoot]

i really don't think you taken into consideration the variables that affect an a/c such as humidity, temperature etc each a/c will respond to differently to these variables plus the numbers you quote are also affected as to the state of the a/c all those max speeds you name depend on fit and finish of a/c from the factory when they achieve max speeds the a/c will have all rough edges smoothed rivets etc plus some poor guy will be waxing it down it rarely happens in real life even the amount of paint is a variable an example of that being a painted 747 can carry 10 fewer pax or equivalent fuel as a unpainted one i think it would be a rare day when any unit a/c can achieve its max speed as stated in manuals back before modern technology every a/c was different some flew higher some were slower then others of same type

 

[FLYBOYJ]

Great stuff JJ! Some of the infomation mentioned is actually shown on modern airspeed indicators, i threw this in here just for ref......

The green should actually be normal operating speeds

i really don't think you taken into consideration the variables that affect an a/c such as humidity, temperature etc each a/c will respond to differently to these variables plus the numbers you quote are also affected as to the state of the a/c all those max speeds you name depend on fit and finish of a/c from the factory when they achieve max speeds the a/c will have all rough edges smoothed rivets etc plus some poor guy will be waxing it down it rarely happens in real life even the amount of paint is a variable an example of that being a painted 747 can carry 10 fewer pax or equivalent fuel as a unpainted one i think it would be a rare day when any unit a/c can achieve its max speed as stated in manuals back before modern technology every a/c was different some flew higher some were slower then others of same type

The air temp, humidity etc is know as "Density Altitude" and is usually calculated in a chart within the POH. Everything else you mention is true and can even go the other way....

 

[DerAdlerIstGelandet]

That is true, FBJ. I know that before we go and fly, we calculate our performance based off of performance charts that include weather, temp, pressure altitude and other variables. This all helps plan our time to target and what we must do in emergencies such as engine failures and stuff like that.

 

[JonJGoldberg]

Reply to Syscom3 >>>
You guys seem always able to ask questions that require thought, however simple on the surface they appear. My answer to the torque effect question is complicated, for the most part is true only for single engine aircraft, would include the -4 as well.

Both the T-bolt Corsair's flight manuals, confirmed by their accompanying 'flight movies' (both available at www.zenoswarbirdvideos.com; all materials seem deletion edited; editorial additions seem limited to company logos, opening credits) present a very simplified, 'official' answer: No applying power changes, other than 'gentle' subtraction, while diving, rolling not withstanding. Further, the training movies strongly 'imply' Half Roll training be preformed in the direction of torque, only one turn (interesting trivia for those '38 enthusiasts) at high altitude, with the power OFF (meaning only enough to prevent your prop from acting as a brake). I believe this strongly suggests, as I'm not a pilot, the seriousness of two factors, torque airframe limits. Not much beyond what was mentioned above is offered in the manuals with regard to torque; there are some further 'clarifications' in explanation of related trim/prop/engine speed settings, but beyond repetitive 'gentle' reminders of respect, imbedded within 'flight envelope' warnings, such as during take-offs, or stalls, they do no go.

What is added now, are my opinions, for single engine aircraft, based on my much modified CFS-2 game its math (flight dynamics) engine, now about 2 ½ generations behind the 'best' games flight engines.

1stly > In an aircraft not modified to perform within the CFS-2 limitations of representing reality, I can do anything. In these modified aircraft I construct I can not, especially when combined with my 'environments', containing weather density altitude variables.

2ndly > The CFS-2 flight dynamics engine is not, with regards to torque effects, very accurate. So far I can not make it completely accurate (math wise); I can not model, nor have I ever seen (flown) a CFS-2 or MS-FS2000 flight model that can correctly represent a '38 on take off, every model pulls one or the other way, slightly, there can be no parity/symmetry; the torque effect must be 'happening' within the game (this has been finally eliminated in MS-FS2K4, but to start again from scratch, in a game that does not support 'combat' is no fun. I await CFS-4).

3rdly > Torque effects are normally (greatly) offset by trim settings implemented during preflight cruise flying. These compensations are evidenced by drag, with dividends including reduced speed, reduced range, increased pilot stress. Once in combat, your trim settings are yet another factor in the equation, by circumstance just as easily representing no correction, as partial correction, or over correction, changing as quickly or remaining as affixed as time, damage or physics allow. Hopefully at least we have as fighter pilots (make believe, or real) acquired the ability to trim the dam aircraft correctly, to compensate for the effects of torque during preflight, the flying time before combat. Anyway, as of today, my sim (make-believe) pilot's opinion is that in most single engine aircraft torque effect is usually best not happening, as it is very difficult to control; you can not retard power during a climb, usually needing all the power she's got to climb; you can not up power in a dive, as gentle reduction of power during a dive to idle is required to stay below Vne keep the engine from over-revving, nor can you usually 'trim' your controls in combat... But the effects of torque are always in fact 'happening' while flying (explaining both the 'short cut' taken in implementing the torque effects in CFS-2, described well above, , although rarely actually put to combat, contra-rotational prop experimentation by all in the real world).

OK now… On my modified aircraft, its taken a few years (starting with less accurate, moving to more accurate as time passed, flight models) to be able to fly either a '47 or 'F4U (high relative mass wing loading) in a sustained powered diving roll needed to induce significant controlled torque effects, in combat, with out causing structural damage, game forced 'over/under 'g' blackout during recovery, engine damage due to 'over rev', or more than 10 sec. of inverted flight, or of more dramatic impact, running out of room/control hitting the ground at 550 mph plus. It's taken some more time, about an additional year or so, to learn how to use this skill, acquired through repetitive reset commands new airframes appearing at command saving my butt, far away from the 'features' available in reality (in other words, acquired through cheating), to an advantage so that I may destroy my sim-enemy, without cheating. I still can not perform them in any 'weather'. The air must be relatively free of added turbulence, IE standard, in box modeled combat missions, containing no turbulence, what so ever (not even those caused by your victim directly in front of you; OK, the CFS-2 flight engine can not reproduce turbulence from your adversary, nor can MS2K4, super computer territory for now) are best for this maneuver; factious dynamic 'missions' where I author in density altitudes, weather (to the limits of CFS-2), are more challenging; rolls are never to be held for more than one roll rotation, extending beyond half roll rotation, except in 'emergency' is not reasonable as you are acquiring speed as fast as gravity, momentum, streamlining can propel you without adding power. A 25 mph gust against your recovery angle, adding to your roll speed, quickly varying your nose dive angles, deflecting your bank angles, as you approach Vne, now there is bound to be some parachuting happening, once you recover from 'g' black out, if you haven't dug a hole, or been killed by your adversary as you pass uncontrollably by offering a wonderful target opportunity. Now you might think you can throw just about everything said directly above, in the trash if we were to be talking about, say a Zero. This aircraft does not accelerate or roll well in a dive, it is of low mass, low wing loading, reasonably, in fact making it far more buoyant, if you would, than either the F4U, or '47. Torque effects may be applied (no films or manuals here, so this is not to say it was/is recommended, or 'officially approved') more easily, but due to narrower flight envelopes, would you? Yep, a skilled pilot during an emergency effectively will, as for the other pilots, there's many a WW2 story about the Zeros wings crumpling while trying to remain on the tail of an American fighter, lots of gun camera footage showing what happens to them in a rolling power dive, as the plane looses controllability. The extremely effective use of power restraint during a dive, enabling combined with relatively high roll rate at speed a higher Vne, further exploited by the wingman tactic as devised by the AVG allowed many a P-40 pilot, to flame, or escape from their Japanese adversaries, fighter bomber alike.

A screen shot of the P-47D's Half Roll Dive Chart is attached. The cut-off altitude numbers are to be found this way on my copy of this film.

As for rolling climbs, this is another matter, one where torque effects are more easily seen, can rarely be exploited by WW2 aircraft, are more often paid for. You usually need all the power she's got to climb in the 1st place, so you're usually running close to, at, or beyond full throttle. Roll speed, bank angles seriously affect climb rates, enough to turn a climb into a dive using a half roll. This is/was done all the time, as by WW2, airframes engines were formidable enough to 'tolerate' these stresses. Using two engines (which my flight sticks throttle can not faithfully reproduce, having only one throttle control) torque may be used, in this envelope to serious advantage. However, this requires of the pilot great skill familiarity with their mount.

So syscom3, to wrap up, the T-bolt could have seriously 'excellent' roll effects from the powerful engine prop. They are rarely wanted, probably contribute to the '47's achievements; at the time (WW2) the '47 had one of shortest life expectancies (not due solely to combat losses, but those losses are included), some of the highest training accidental loss rates (http://www.taphilo.com/history/WWII/Loss-Figures-Aircraft-USA-Training.shtml). These honors are duly offset by the fact that most of its Aces survived the war.

Reply to pbfoot >>>
FBJ answered well for me. Thanks FBJ. I'd like to apologize for not defining the term density altitude contained in my reply to Monkeysee1. I'd also like to add to FBJ's comments on the effects of paint rivets finish. I find your arguments, for the most part, very valid. As to why they are not considered, I would answer you this way: To be able to accurately model 'Aircraft X' into a single representative I can embody the measured flight characteristics of a 'number' of known examples 'Aircraft X' into a single representative model. This to you would be accurate, but I'd argue the degree of accuracy depends on the skill of the pilot, the number of samples, their condition vs. the stats, the number produced thier delivered condition. Rather I feel the numbers that would best represent 'Aircraft X', offer the least variance would be one developed from the specifications that represent the 'goal' of production. After we agree that this model indeed accurately represents 'Aircraft X', we may from here reproduce the flight characteristics of any uniquely aged, finished, painted, assembled, or cared for example of 'Aircraft X' you or I desire. This discussion is, how ever valid your point, not centered on any single example, rather it is centered on the single representative of Aircraft X.

Reply to DerAdlerIstGelandet >>>
Thanks for the compliments, affirmations.