Diving - which fighters used it best, and how?

[GregP]

The Spitfire XIV was very probably the best climber of the war. The Me 109K was near it, at a MUCH lower speed of climb. Since the P-47 with the wide-chord prop was near these two stellar cimbers, my point is well made. The early P-47N-5 climbed at slightly over 4,200 fpm at sea level and was still clibing at 3,750 fpm at 28,000 feet. Later N's were a bit better. numbers for P-47N-5 from wartime report number E5-302-A, available on the web at http://www.wwiiaircraftperformance.org/p-47/p-47n-republic-wep.jpg.

The P-47N's, especially the late models, were the fastest planes of the war bar none, at altitude, and 470+ mph in service, in numbers. Some others mathched and exceeded the P-47N's speed after the war, but not during the war. I'm not talking about prototypes, I'm talking about deployed, normal operational types. Protypes, while interesting, especially to me, are meaningless in wartime operations.

Normal operations, to me, means more than 1,000 built and deployed. There were 1,816 P-47N's built and 1,667 built in WWII, with most deployed during WWII. Numbers like 43 built, as in the Ta-152 are a batch of hastily-deployed prototypes (never more than 25 in service at any one time), and they were not operational after the first malfuntion, due to no spare parts in the logistics system and all parts needed for new production. Nothing wrong with the Ta-152 at all; just not a factor in any wartime operations, so please spare us the prototype performance debate, it is meaningless in the scheme of WWII operations.

But, if 1,000 or more were built and deployed in WWII, then go for it. More than, say, 200, were operational, but hardly well-deployed and were sort of operational ... but not really, except ina small group.

The Me 109K was fast (about 440 mph or so) and climbed well, but was not maneuverable or much of a a threat above 400 mph, as any Me 109 pilot can tell you. At that speed, they were running to save their lives. Their combat speed was around 350 mph if they were going to fight and maneuver. But get fast and climb with the best (at a lower speed), they could if necessary. It rarely was except to catch something. When they DID, they slowed down to attack unless it was to be a tail chase. If so, the target was likely to be able to out-maneuver the Me 109K at high speed. If both slowed down, it migh be a fight. For instance, I believe the Me 109K could ctach most Mosquitos. But catching it and making a kill of it are two different things.

 

[wuzak]

The Spitfire XIV was very probably the best climber of the war. The Me 109K was near it, at a MUCH lower speed of climb. Since the P-47 with the wide-chord prop was near these two stellar cimbers, my point is well made. The early P-47N-5 climbed at slightly over 4,200 fpm at sea level and was still clibing at 3,750 fpm at 28,000 feet. Later N's were a bit better. numbers for P-47N-5 from wartime report number E5-302-A, available on the web at http://www.wwiiaircraftperformance.org/p-47/p-47n-republic-wep.jpg.

That chart shows a rate of climb of just over 3600ft/min at sea level, and 2400ft/min at 28k ft.

Time to 25k ft is around 8 minutes (using WEP all the way), at which time the Spitfire XIV is some 5000ft higher!

The P-47's climb in no way compares to the Spitfire XIV's until over 30,000ft, and then it only appears to match it.

The Spitfire IX, depending on engine and altitude, could outclimb a XIV.

 

[MikeGazdik]

Anyone have any info on the dive speed / handling / zoom of the F4U Corsair?

 

[wuzak]

http://www.wwiiaircraftperformance.org/f4u/jt259-handling.pdf

See section 4.23


Also:

The F4U's appear to be superior to teh P-51B under all conditions in level flight acceleration, in maneuverability, and in response. The P-51B has markedly superior diving acceleration

http://www.wwiiaircraftperformance.org/f4u/p-51b-f4u-1-navycomp.pdf

 

[drgondog]

The pre-paddlepop prop P 47 (say that fast five times!) certainly had a reputation as a poor climber, at least at low to medium/high altitudes. The D models apparently improved markedly in this respect, although I agree with WuzaK (shock, horror!) that's its questionable whether they matched dedicated climbers like the 109K or Spit XIV at any altitude.

The later D's (post -11) with WI and Paddle blades did in fact climb with or climbed faster above 30,000 feet due to the supercharger and continuously uprated R-2800 hp...as it continued to perform when the Spit and 109 went well beyond their critical altitude. Having said that, it would entirely depend on the condition of the engines for the P-47D to climb faster above 30,000 feet than the Spit IX or XIV

But then as an escort fighter they didn't really have to, I guess. The Thunderbolts could fly above the bombers, which was where the German fighters had to go, and intercept by doing what they did best – diving.

Depending on the tactical situation even the FW 190's preferred to get to 28-30,000 feet and start downhill - and the 109 escorts in 1944 were frequently entering the attack area at 32-35K.

One other thing - didn't the later P47 have dive flaps, like the P38L? But the P-51 didn't - was this a reflection of the Mustangs higher critical mach number and therefore contrallbility at higher dive speeds than the other two fighters?

Yes the P-47D-25 (IIRC) and beyond had a dive 'flap' around the 30% chord line similar to the P-38 for the very same reason.

The region of Drag divergence moved to the area of aerodynamic center/max T/c for both the P-38 and P-47, then from that state to critical mach where the shock wave formed and started moving aft. During that transition, the Mac caused a nose down pitch - The effect of the dive flap was to delay the transition and enable the pilot to get control of the dive.

The Mustang max t/c was near 40% which had two effects. First was a more gradual gradient for the pressure distribution over the airfoil, delaying the critical velocity at which Drag Divergence (local near supersonic/pre-shockwave) formed. Second, the effect of a shock wave forming at ~40% chord was a much reduced Pitching Moment.

Simply, the 51 didn't 'tuck' like all the rest of the conventional wing fighters.

As to the necessity of Roll before Dive? Only if you had to follow the guy in front, or your roll was an evasion manuever coupled with a climb - then split S... but IIRC all the tests performed by RAE for dive measurement was simply fly in parallel and push the stick forward.. trust me that a 51 does not need to roll and split S to initiate a wild ride 'south',

 

[Vincenzo]

P-47N were deployed from april '45, only N-1 and N-5 were used in WWII the production of this 2 variant was 1,100.
1,667 is the production until december 1945 for Farmingdale factory

 

[davparlr]

That chart shows a rate of climb of just over 3600ft/min at sea level, and 2400ft/min at 28k ft.

Time to 25k ft is around 8 minutes (using WEP all the way), at which time the Spitfire XIV is some 5000ft higher!

The P-47's climb in no way compares to the Spitfire XIV's until over 30,000ft, and then it only appears to match it.

The Spitfire IX, depending on engine and altitude, could outclimb a XIV.

There is some confusion on the performance of the P-47N. The referenced site shows correct weight but is probably an engineering analysis not flight test data. These tend to be optimistic, which is confusing. Flight test data as shown by this site,
http://www.wwiiaircraftperformance.org/p-47/comp-p47dmn.jpg ,

shows a significant difference in tested weight of the N compared to the D and M. Just looking at the M, it has a basic weight increase over the D, most likely due to the new engine and larger turbo-supercharger, of 236 lbs and tested weight increase of 531 lbs, for some odd reason. However the N, with a basic weight of 300 lbs more than the M, due to bigger wing and installed wing tanks, shows a tested weight 2528 lbs more than the M. If corrected for over weight conditions, the N should handily out climb the M, and besting 4000 ft/min, which would make some sense since the wing loading is better on the N.

While there is conflicting data, I suspect that if the Spitfire XIV and P-47N performance would be quite close at equal fuel weights (the spit carries much less fuel). The N engine produced a flat rated 2800 hp up to 33k, much more powerful at high altitudes than any other fighter including the dual engined Do 335.

 

[davebender]

much more powerful at high altitudes than any other fighter including the dual engined Do 335.

The Do-335 was a high speed light bomber complete with bomb bay. A 1945 version of the 1960s F105. One would expect such aircraft to be optimized for low level performance.

 

[CobberKane]

Yes the P-47D-25 (IIRC) and beyond had a dive 'flap' around the 30% chord line similar to the P-38 for the very same reason.

The region of Drag divergence moved to the area of aerodynamic center/max T/c for both the P-38 and P-47, then from that state to critical mach where the shock wave formed and started moving aft. During that transition, the Mac caused a nose down pitch - The effect of the dive flap was to delay the transition and enable the pilot to get control of the dive.

The Mustang max t/c was near 40% which had two effects. First was a more gradual gradient for the pressure distribution over the airfoil, delaying the critical velocity at which Drag Divergence (local near supersonic/pre-shockwave) formed. Second, the effect of a shock wave forming at ~40% chord was a much reduced Pitching Moment.

Simply, the 51 didn't 'tuck' like all the rest of the conventional wing fighters.

As to the necessity of Roll before Dive? Only if you had to follow the guy in front, or your roll was an evasion manuever coupled with a climb - then split S... but IIRC all the tests performed by RAE for dive measurement was simply fly in parallel and push the stick forward.. trust me that a 51 does not need to roll and split S to initiate a wild ride 'south',

Regarding Roll before dive, surely this was a nessecary manouver to avoid 'red out.'? I know early war 109 pilots used to bunt straight into a dive to escape Spitfires and Hurricanes as their fuel injected engines would continue to operate, but this wouldn't have needed to be a particularly violent move, just enough to generate negative Gs. In fact the longer and slower the manouver the more time the 109 would have under power while the Spit or Hurri was falling behind I guess. Likewise, when trying to compare the dive speeds of two planes in a controlled enviriinment the best option would be to simply push the stick forward steadily. But when someone is on you tail and dive aceleration is your trump card i would have thought you would want to get into that dive asap without bursting every capilliary in your eyeballs - in other words a split-S. So if diving was invariably preseded by a roll in combat, it follows that any plane that had a good reputation as a diver most likely was a good roller as well. This certainly seems to be the case with the P-47

 

[MikeGazdik]

In reference to the high speed dive of the Spitfire. With all due respect to that lovely airplane. How does a dive that destroys the airplane, and is lucky to land, proof that it is the supreme diving aircraft????? The destruction is evidence that the limits of the airframe were exceeded.

 

[wuzak]

It was going somewhat faster than its contemporaries could in a dive.

But it was done in the name of research.

 

[CobberKane]

In reference to the high speed dive of the Spitfire. With all due respect to that lovely airplane. How does a dive that destroys the airplane, and is lucky to land, proof that it is the supreme diving aircraft????? The destruction is evidence that the limits of the airframe were exceeded.

Only Martindales plane was destroyed, the other two apparently survived, though Brown's Spitfire can be discounted due to it's new tail. And no, I wouldn't describe the Spitfire as a supreme diver because, as I mentioned earlier, I believe that a fighter's reputation as a diver in combat situations included roll rate, which would put the aircraft on the chosen plane before diving, and acceleration in the dive, which would close the gap on a target or open the gap from a pursuer. Neither of these factors were examined in the RAE tests, although the outright speeds reached by the Spitfire does emphasise what a remarkable design it was.
I think rate of roll is one of the most underestimated performance criteria of all fighters. Wth the exception of the loop and the chandelle (which is effectively an abreviated loop) all acrobatic manouvres begin with a roll. I believe that this is the key to the reputation of the P47 as a great diver; very few aircraft would have been able to stay with it as it rolled and the few that could would not have been able to keep up once it accelerated into the dive. commenced.

 

[Hop]

How does a dive that destroys the airplane, and is lucky to land, proof that it is the supreme diving aircraft????? The destruction is evidence that the limits of the airframe were exceeded.

Diving to Mach 0.891 did not destroy the aircraft. The aircraft in question was a Spitfire XI, serial number EN 409. It was used for tests in 1943. In January 1944 the RAE issued an interim report that included details of a "typical" dive to mach 0.891.

Several months after that report, in April 1944, the same Spitfire, EN 409, was destroyed in another diving accident. We don't really know what speed it got up to before the accident occurred.

And it wasn't the limits of the airframe that were exceeded, iirc. The constant speed unit (prop gearbox) failed, causing the prop to tear away.

But the cause is immaterial. We have a test report showing the Spitfire reaching mach 0.891 safely. There is no mention of damage. Indeed, there can't have been significant damage or they wouldn't have been using the same aircraft for high speed research months later.

 

[FLYBOYJ]

Wth the exception of the loop and the chandelle (which is effectively an abreviated loop).

Not true...

A chandelle is a control maneuver where the pilot combines a 180° turn with a climb.

The Idea is to start the maneuver at maneuvering speed and complete the maneuver 180° from your starting point just about at stall speed. As you climb and bank you're reaching a bank angle between 30 and 40 degrees.

This is a Chandelle...

 

[VBF-13]

The F6Fs were very effective at dive-bombing on both land and sea targets. They proved that over and over, since their inception. Such was built into them by Grumman. Think of the constraints attendant to deploying aircraft from carrier decks as opposed to from land runways. Although the carriers carrying the F6Fs were Essex Class in size, Grumman built every conceivable role they could into those aircraft short of torpedo-bombing because of the space constraints, even on those big carriers.

As far as generally what makes for a good dive-bomber, you get a decent fighter-bomber aircraft, it's more the pilot training and skills, than it is anything else. The SBDs, with their perforated brake flaps, were ideal dive-bombers. However, you don't have the requisite training and skills, you don't hit the broadside of a barn in one of those.

 

[barney]

To me, when we talk of diving, I don't think of a shallow dive to drop a bomb or strafe an airfield, I think of the monumental dives from bomber altitude to deck chasing or being chased by e/a.

When entering a dive, most planes had to be trimmed a certain way, altitude and speed had to be monitored and the pullout begun at a specific altitude depending on the speed and altitude where the dive was initiated. I can imagine this easily going wrong in combat.

So, I suggest the best diver would be the plane most likely to keep you alive when the execution of this maneuver is less than perfect. Better yet, I think a wise pilot in chase would feign the vertical dive and then go shallow. Let the guy below display his diving skills.

 

[CobberKane]

Not true...

A chandelle is a control maneuver where the pilot combines a 180° turn with a climb.

The Idea is to start the maneuver at maneuvering speed and complete the maneuver 180° from your starting point just about at stall speed. As you climb and bank you're reaching a bank angle between 30 and 40 degrees.

This is a Chandelle...

...Which would seem to leave the loop as the only acrobatic move not incorporating a roll, which emphasises my point rate of roll is a vital ingredient of that mysterious quality, manouverablity - at least as important as turning radius, which so many comentators seem to regard as the be-all and end-all of an aircrafts dogfighting ability.

 

[FLYBOYJ]

...Which would seem to leave the loop as the only acrobatic move not incorporating a roll.

For the most part, CORRECT!

 

[davebender]

Do you have historical F6F bombing accuracy results to support that claim?

 

[VBF-13]

Do you have historical F6F bombing accuracy results to support that claim?

I beg your pardon? Why don't you research NAS Fallon, NV, late-1944, early-1945, for starters. Find out what the boys over there in those bombing-fighting squadrons were training on. I'll give you a hint, it wasn't just gunnery target practice and acrobatics. The F6Fs were made to dive-bomb, that was a built-in role. They were bombing-fighting aircraft, not just fighting aircraft.