Diving - which fighters used it best, and how?

[CobberKane]

I pressed Wing Captain Brown on this topic back in the 80's and could get no back up to his claim that the Mcr of the FW 190 was higher than both the P-47 and P-51, enabling it to dive faster. I'm open to belief that RAE tested all three to critical limits but I have only found the Mustang IV and P-47D-30 (?) dive tests (with wing flap), which given all the access via internet is pretty curious that the results for 190 and 109 are not available.

As to accelerating in a Dive - and then extending the lead - the Mustang out accelerated the Spit IX at all altitudes then maintained the separation, the Tempest V above 24000 feet (the Tempest slightly superior below 24,000 feet), the FW 190 and Me 109G always at all altitudes according to the RAF Wettering report dated 8 March 1944. These are the only published Tactical Comparisons I have seen.

Page 58-61 of Jeff Ethell's "Mustang"

The Army Air Forces Board Project No. (M-1) 50 "Tactical Employment Trials on North American P-51B-1 Airplane" was a Tactical Trial between the P47D-10, P-38J-5, the P39N-0 and P-40N.

Comments - regarding individual characteristics in which the Mustang was out performed.
1. Both the P-39 and P-40 had a slightly better turn.
2. The P-47 had a slightly better rate of Roll, but the P-51 has a faster rate of roll than all the others
3. It notes that only the P-38J can initially out-accelerate (to a couple of hundred feet in front), before being rapidly caught from behind by the 51 from level flight.
4. The P-38 and P-51 are even in Zoom cimb initially from level flight at low and medium speeds, but the P-38 keeps climbing after the 51 falls away. At high speeds however the 51 pulls away and zoom ends 'considerably higher'.
5. The P-51 out zooms the P-47 from level flight at all speeds, and recovering from dives the P-51 out accelerates and outclimbs the 47.
6. The P-47 is slightly faster than the P-51 above 30,000 feet but the Mustang will attain 400 mph all the way to 40,000 feet.

One other important note - "The P-47 and P-51 are equal in Dive from level flight but the P-51 'jumps ahead several hundred feet' then maintains that separation neither gaining nor losing distance."

Inference - if the FW 190 and Me 109 have a superior dive speed according to Brown to both the P-51 and P-47 then the acceleration period to terminal dive velocity should be a pretty short interval - implying that neither the Mustang nor Thundebolt should Ever catch the 109/190 in a dive initiated from equal altitudes if the German fighters have several hundred yards of separation. History is unkind to that theory.


Pages 49-50 from Jeff Ethell's "Mustang" - I haven't looked but think this report is on SpitfirePerformance website.

The net of the discussion is there seems to be no published comparisons citing the Fw 190 or Me 109 as superior either in dive acceleration or max dive velocity to either the Mustang or Thunderbolt.

Which would seem to support the almost universal experience of pilots that the P-47 could out-dive the 109 or 190. Oddly, though, it seems the P-51 was at least as good in this respect as the P-47 but doesn't have the same reputation. Maybe diving represented the most significant advantage of the P 47 over the German fighters and thus came to be a more commonly used tactic agianst them - thereby cementing its superiority in this respect in the minds of the pilots - as compared to the P51, which had other options?
Then again, I have a DVD in which a P-51 pilot says: "Intellegence told us we could outdive them, but we couldn't. At least I couldn't outdive the one that was after me, and I was going straight down at full throttle."
The Thunderbolt was also renowned for its steadyiness at high speeds, which doubtless made the option of diving attacks that much more attractive. The Tempest was also apparently very good in this regard. At least one kill was claimed to have been scored at well over 500 mph. There probably aren't too many aircraft that could be used as a gun platform at those speeds, even if they could get there.
At the end of the day I'm not about to discount the P 47 as a supreme diver - there is just too much anecdotal eveidence to support this. By the same token I'm not inclined to discount Browns assertion that the 109 and 190 could reach higher speeds under controlled circumstances, but whether it was practical for them to do so in combat might be a different matter. I suspect that reconciling this apparently contradictory information lies in recognising that use of the dive in a combat situation is a lot more complicated than just pointing the nose down and opening the throttle!

 

[davparlr]

Then again, I have a DVD in which a P-51 pilot says: "Intellegence told us we could outdive them, but we couldn't. At least I couldn't outdive the one that was after me, and I was going straight down at full throttle."

There were some late model Bf-109 models like the G-10 and K that were quite a challenge to the P-51D. These were much too late to have an affect on the war, but did cause some consternation with the allied pilots when they ran into one.

 

[Vincenzo]

for Gordon Levett 109 (for true S-199) outclimb, outdive and outzoom the P-51D and the Spitfire L.F. IX
Aircraft

 

[Glider]

A flippant reply to the original question Diving - which fighters used it best, and how?

The ones that used it best were those that could dive the fastest, and did it going down hill

Sorry couldn't help it

 

[FLYBOYJ]

As far as wings ripping off one has to account for different variants that had different armaments in the wings. More guns.....heavier wing that would come off more easily than a wing with less guns in it. I believe in testing either a version of the mustang or even the jug shed its wing because of steps taken to lighten the aircraft and less guns were put in to compensate until the wing root was strengthened. Can't remember where I read that but I will check my "jug bible" when I get home tonight.

Is this for the P-47 in general? In many cases a "loaded" aircraft will handle turbulance and rough air pentration better than being flown at a lighter weight.

 

[drgondog]

Which would seem to support the almost universal experience of pilots that the P-47 could out-dive the 109 or 190. Oddly, though, it seems the P-51 was at least as good in this respect as the P-47 but doesn't have the same reputation. Maybe diving represented the most significant advantage of the P 47 over the German fighters and thus came to be a more commonly used tactic agianst them - thereby cementing its superiority in this respect in the minds of the pilots - as compared to the P51, which had other options?
Then again, I have a DVD in which a P-51 pilot says: "Intellegence told us we could outdive them, but we couldn't. At least I couldn't outdive the one that was after me, and I was going straight down at full throttle."

Its entirely irrelevant to proof points but my father scored three of his six air kills against 109s by cathing up to 109s in a dive that had a head start (7-28-44 and 9-11-44) plus two in turning fights within a Lufberry (6-20-44) and one in which he split S in less altitude than the 109 he had cornered (8-6-44).

The Thunderbolt was also renowned for its steadyiness at high speeds, which doubtless made the option of diving attacks that much more attractive. The Tempest was also apparently very good in this regard. At least one kill was claimed to have been scored at well over 500 mph. There probably aren't too many aircraft that could be used as a gun platform at those speeds, even if they could get there.

At the end of the day I'm not about to discount the P 47 as a supreme diver - there is just too much anecdotal eveidence to support this. By the same token I'm not inclined to discount Browns assertion that the 109 and 190 could reach higher speeds under controlled circumstances, but whether it was practical for them to do so in combat might be a different matter. I suspect that reconciling this apparently contradictory information lies in recognising that use of the dive in a combat situation is a lot more complicated than just pointing the nose down and opening the throttle!

I don't ever 'dismiss' Brown but he never delivered on the proof points regading a.) side by side tests of 109/190 vs 51/47 in which the 109/190 'won', nor did he b.) refute the RAE tests in March 1944 in which the opposite conlusion (from Brown's) regarding 51/47 Dive performance in head on Comparisons. Ergo, to me its an interesting theory that is contrary to several hundred Combat Encounter Reports in ETO

 

[CobberKane]

I don't ever 'dismiss' Brown but he never delivered on the proof points regading a.) side by side tests of 109/190 vs 51/47 in which the 109/190 'won', nor did he b.) refute the RAE tests in March 1944 in which the opposite conlusion (from Brown's) regarding 51/47 Dive performance in head on Comparisons. Ergo, to me its an interesting theory that is contrary to several hundred Combat Encounter Reports in ETO

I think that sums it up pretty nicely. Re 'dismissing Brown' - it was just a general comment that anyone should be cautios about disreagrding the opinions of such an experienced pilot - but we are also entitled to ask why that opinion seems to contradict the great bulk of combat experiences. That's why I was speculating about factors like acceleration, or stability as a gun platform as contributing to the P47s reputation as a diver.
I'm intrigued by the data that suggests the P51 was at least as good in this respect, yet it is the P-47 that gets all the accolades

 

[MikeGazdik]

I don't have the technical knowledge to explain this , but could it be a result because of the weight of the aircraft? The P-47 being so heavy, when pushed over or rolled over on her back and begins to dive, the weight lets the airplane use its energy and it quickly gains speed in the dive. Much faster than its lighter foe, in this case an Me109 or Fw190. The same would hold true of a P-51 vs the German fighters. Again its weight lets it gain speed faster, in the first few critical moments. Now once into a more sustained dive, aerodynamics become more important and the cleaner or smaller airframes "catch up". The Mustang being cleaner than the Thunderbolt ultimately surpasses the speed that the Thunderbolt can obtain. And the same with the Messerschmitt, where eventually it may be able to obtain a higher speed in a dive than a Mustang. But in real world combat, the Thunderbolt or Mustang in its initial surge of speed in the dive catches the Messerschmitt before it can get away and the plane is shot down. A situation where testing, with no bullets flying, shows one result but in combat another opposite result usually occurs.

 

[drgondog]

I don't have the technical knowledge to explain this , but could it be a result because of the weight of the aircraft? The P-47 being so heavy, when pushed over or rolled over on her back and begins to dive, the weight lets the airplane use its energy and it quickly gains speed in the dive. Much faster than its lighter foe, in this case an Me109 or Fw190. The same would hold true of a P-51 vs the German fighters. Again its weight lets it gain speed faster, in the first few critical moments. Now once into a more sustained dive, aerodynamics become more important and the cleaner or smaller airframes "catch up". The Mustang being cleaner than the Thunderbolt ultimately surpasses the speed that the Thunderbolt can obtain. And the same with the Messerschmitt, where eventually it may be able to obtain a higher speed in a dive than a Mustang. But in real world combat, the Thunderbolt or Mustang in its initial surge of speed in the dive catches the Messerschmitt before it can get away and the plane is shot down. A situation where testing, with no bullets flying, shows one result but in combat another opposite result usually occurs.

Take it to the extreme if you think the heavier airplane accelerates faster.. P-51 and B-17 nose over at the same time..

From a Physics POV, the key factors are Thrust and Drag. Weight will have a contribution to the vertical acceleration as it adds to the Thrust developed by the Propeller/engine system but you have to look at the effect carefully as you differentiate Velocity with respect to time. (acceleration)

In my example above the drag differential between the P-51 and B-17 is enormous. In a dive it would seem as if the B-17 had a drag chute attached as it pitches over.

 

[MikeGazdik]

I understand what you are saying, and I understand the reason for the extreme example. However does this mean that weight has nothing to do with the dive? As in stored energy? What about two similar airplanes. A lightly loaded P-51, with 1/4 tanks of fuel, ammo expended, vs a fully fueled Mustang with full ammo load. However brief, wouldn't the weight of the heavier P-51 help it accelerate quicker to its maximum dive speed?

 

[CobberKane]

I understand what you are saying, and I understand the reason for the extreme example. However does this mean that weight has nothing to do with the dive? As in stored energy? What about two similar airplanes. A lightly loaded P-51, with 1/4 tanks of fuel, ammo expended, vs a fully fueled Mustang with full ammo load. However brief, wouldn't the weight of the heavier P-51 help it accelerate quicker to its maximum dive speed?

My knowlege of physics is pretty basic, but I would cite the example of a watermaelon and and apple being dropped at the same time - they hit the ground at the same time too. Hence, if air resistance were not a factor weight would not affect acceleration in the dive. The determining factor would be thrust alone.
However, in real life we do have to deal with air resistance we and this brings drag into the picture. More drag means less acceleration in the dive. But even if we had two aircraft with identical drag properties and power, if one were significantly heavier than the other it would have an advantage in the dive because it would also have a higher wing loading, and aircraft with higher win loading generally tend to retain control at high speed better than aircraft with lower wing loading. So by my reckoning, while a heavier aircraft might not have any advantage in the initial stages of a dive (all other things being equal) it may very well have an advantage as the dive progresses and the speeds rise.
Having said all that, anyone with a better knowlege of physics feel free to shoot me down

 

[riacrato]

I don't have the technical knowledge to explain this , but could it be a result because of the weight of the aircraft? The P-47 being so heavy, when pushed over or rolled over on her back and begins to dive, the weight lets the airplane use its energy and it quickly gains speed in the dive. Much faster than its lighter foe, in this case an Me109 or Fw190. The same would hold true of a P-51 vs the German fighters. Again its weight lets it gain speed faster, in the first few critical moments. Now once into a more sustained dive, aerodynamics become more important and the cleaner or smaller airframes "catch up". The Mustang being cleaner than the Thunderbolt ultimately surpasses the speed that the Thunderbolt can obtain. And the same with the Messerschmitt, where eventually it may be able to obtain a higher speed in a dive than a Mustang. But in real world combat, the Thunderbolt or Mustang in its initial surge of speed in the dive catches the Messerschmitt before it can get away and the plane is shot down. A situation where testing, with no bullets flying, shows one result but in combat another opposite result usually occurs.

My naive understanding is the same, that's why I wonder why such a big fuss is made of it over several pages. The drag of all four aircraft will be "close enough" in the equation drgondog outlined. So initially I guess the difference in mass and thrust (of which the P-51 and P-47 both have more than the Me 109 or Fw 190) will lead to a faster dive in the first stage of the dive. And if that stage is long enough for the pilot to get into a shooting position, than his plane surely dived better than his opponent's.

If the small airframes of the 109 and 190 enable higher diving speeds but they achieve them only considerably later than the 51 or 47 in the same dive... than that seems entirely possible to me, but less meaningful, outside a few probably isolated instances. Though I would've personally guessed the P-51 to have the highest diving speed limit thanks to its clean airframe.

 

[Vincenzo]

if i remember right reports on williams pages the german fighters were faster in early dive

 

[drgondog]

The aircraft one with better acceleration will initially outgain the other, independent of Gross Weight, then Drag will take over as Drag will at some (very close point in) time equal to Thrust.

In a Free Body Diagram, in equilibrium (i.e no more acceleration) the Vertical Force in a 90 degree dive

Thrust + Weight = Drag

Explaining it in terms of P-47 vs P-51. The 51 out accelerates intitially, the P-57 closes and maybe starts to achieve a slightly higher speed - which in a long dive may enable the 47 to catch up. In this example the drag differential is slightly offset by weight differential but both have nearly the same Mcr

PS - the physics goes to hell in a handbasket when the Q loads overwhelm the airframe..

In terms of a P-51 versus P-38 - the P-38 initially gains a few feet in the push over but the 51 catches up and accelerates past the 38 before the 38 runs into compressibility, then opens the distance significantly. The Mcr of the 51 is higher.

For P-51 vs Me 109 - the 109 (late G/K) initially accelerates and gains a slight lead, then the P-51 closes and catches up due to the Drag and weight differential.

I have not seen the Mcr data for the 109 but suspect it is lower than the 51.

BTW - these Force balances go to hell in a handbasket when the Q loads overwhelm the structure..

 

[duplex]

View: https://www.youtube.com/watch?v=KmRfBsaUN8o


The legendary German ace Gunter Rall says P-47 was superior to 109 in dive which means that P-47 must have been much better than Spitfire by a huge margin as 109's have comfortably outperformed the Spitfire's in BoB

 

[Shortround6]

See Drgondogs previous post.

putting it a bit differently

You have at least three things affecting dive, one is how fast the plane accelerates in the dive. The Spitfire was not good at this.
The 2nd is how fast the plane will ultimately go in the dive given enough height and time. The Spitfire could reach very high speeds but the other plane might well have out accelerated it and gotten out of range by the time the Spitfire got to a point were it was faster (or caught the Spitfire).
3rd is what the ultimate dive speed of the plane is and why. Many 1930s biplanes had so much drag they hit a speed in a dive and simply couldn't go any faster. Most monoplanes didn't have this problem. However they had structural limits, pieces would start falling off the plane at high speed. They had control limits, aerodynamic loads on the control surfaces reached a point where the pilot could not move them using muscle power. And they had aerodynamic limits, at high speeds the airflow changed over the wing and aircraft surfaces and change the center of lift of the wing and or change the airflow over the control surfaces which changed the trim of the aircraft making it difficult or impossible to control. Some planes went into mach tuck. the plane steepened the dive without any input form the pilot (or the pilot could not pull out of the dive). A few planes were trimed such that they tended to pull out of the dive and the pilot could not keep them diving at the same angle using all his strength on the control column.

The P-47 accelerated very quickly in a dive, it also kept aileron effectiveness to rather high speeds making it easy (comparatively) to roll or turn in the dive. Even though the Spitfire (and be careful of the Mark of Spitfire) might actually be able to reach a higher speed given enough altitude. The P-47s did have a problem with compressability.

Also please note that since weight makes up a good component of the dive acceleration/speed comparing a 1940 6000lb Spitfire to a 1944/45 8400lb Spitfire MK XIV might lead to some wrong conclusions.

 

[tomo pauk]

The legendary German ace Gunter Rall says P-47 was superior to 109 in dive which means that P-47 must have been much better than Spitfire by a huge margin as 109's have comfortably outperformed the Spitfire's in BoB

This post is futile attempt to bash Spitfire, without any facts to prove the point.

 

[pbehn]

This post is futile attempt to bash Spitfire, without any facts to prove the point.

I have seen two videos of RAF and LW aces that support this but it must be seen in context. It is no great recommendation for the 109 that it could out dive the spitfire in 1940, The Bf109 was supposed to be defending the bombers this is no done well by diving away.

 

[Shortround6]

you can't defend the bombers if you are shot down. If the 109 had a Spitfire on it's tail then diving is a valid way of breaking contact.
Staying and acting as a bullet sponge so the Spitfire doesn't attack the bombers means fewer escorts the next day or next week.
It wasn't mano a mano duels but a war of attrition between groups/formations.
Breaking contact when disadvantaged means, depending on fuel state, being able to rejoin the group several minutes later and resuming duties, or at least sucking the Spitfire/Hurricane into diving after the 109 which also takes them out of intercept position against the bombers.
A lot depends on relative positions (in every sense, actual location, altitude, direction and airspeed) of the aircraft and the numbers of aircraft. 9-12 Spitfires attacking with 20+ 109s defending 30+ bombers?

One size does not fit all situations. diving away is just one tool in the tool box.

 

[duplex]

This post is futile attempt to bash Spitfire, without any facts to prove the point.

A futile attempt ? I don't have to prove any point its a common knowledge .Even the eminent BoB historian James Holland came to the conclusion ( you must assume he did his own research )

James Holland's Griffon Merlin | The Me109 v Spitfire Debate Keeps Going

People can argue all they like about handling, wing-loading, under-carriage widths etc etc, but the bare-faced facts are these: the Me109 could climb faster, had considerably greater fire-power, and could dive faster. That made it the best air-to-air fighter of 1940. That's not a debate, it's a fact.


I fully understand Britains emotional attachment to Spitfire but there is the reality , it had its weakness during BoB nobody can deny ..