Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Agree with Davpair - standard LW fighters of crucial 1st half of 1944 were in notable disadvantage vs. P-51B/C/D. 650/660 km/h vs. 700 km/h was (and still is) disadvantage. When we include that P-51 was already in it's best altitude, with better pilot, and range to prosecute anywhere within area of interest, the writing was on the wall. The other plane from topic (D-9) managed just to equal (if even that) the speed, climb rate maneuvrability, but other issues remained. And only half a year later; a full year vs. P-51B.
To put it shortly, P-51D could have done anything D-9 could, while vice-versa was not possible.
What is the corresponding boost for 75" in the British system?
Knegel - the US did not have 'overwhelming' air superiority in numbers of strategic fighters until perhaps Dec 1944 and certainly after Bodenplatte.
Hello Vanir
Quote:"the very fact so many German aircraft were shot down by friendly fire during Bodenplatte is testament to this."
That's not a fact but a myth, originating from Galland I think. But there were some LW losses to German AAA, more on question that so big German formations were seldom seen near frontlines.
Juha
Hi,
you shouldnt forget that the Speed of the P51 is always given with WEP, while the speed of the 109G without MW50 is mainly with combat climb!!
Knegel said:you shouldnt forget that the Speed of the P51 is always given with WEP, while the speed of the 109G without MW50 is mainly with combat climb!!
Since late 1943 the 109G also had WEP available. Specialy regarding the P51B in 1943( -3 engine) you will find that it was not faster than the clean 109G-1/2 + WEP between 5500 and 7000m and i guess the P51b without WEP wasnt faster there as well. And specialy in high alt speeds was fast much below Vmax.
The clean 109G made around 640km/h on combat climb and + 20-30km/h on WEP. Thats what the P51B mase in around 6000m, also with WEP.
The climb of the clean 109G-1/2 was as good or better than that of the P51B/D up to 6000m, all over rather similar. Once again you should look to combat climb, not the WEP test.
Dont look to the late war climb datas of the MW50 powered engines, cause this combat climb datas are with less power than the early DB605A, while they also could climb with Sonder-Not(MW50), unfortunately there are only a few climb tests made with this setting, and i never saw a good one(with background datas).
The 109 had clear handling advantages in high alt(mainly rather slow speeds IAS), but anyway, thats later.
I am a bit confused by what you have said here but I can be slow. I will confess that I have limited data on the Bf-109 so I can't argue your points knowledgably. So, lets assume my data for the Bf-109G is at combat rating, that is, no water injection or WEP. This is a comparison, right or wrong. Power settings for the P-51B(-3 engine) is at 60" (close to Normal Power) and the P-51B(-7 engine) is at 67" combat power. These data are from AAF flight test with aircraft tail number and weight identified. Note: The -3 engine P-51 is a couple hundred pounds under fighter weight, which would affect climb. The -7 is at fighter weight.
SL a/s(mph) climb rate(ft/min)
P-51B-3 348 3600
P-51B-7 357 3780
Bf-109G 326 3678
10k ft
P-51B-3 386 3540
P-51B-7 407 3310
Bf-109G 362 3060
20k ft
P-51B-3 424 2915
P-51B-7 427 3080
Bf-109G 399 3094
25k ft
P-51B-3 427 2600
P-51B-7 440 2350
Bf-109G 397 2240
30k ft
P-51B-3 441 2250
P-51B-7 429 1600
Bf-109G 400 1625
It is apparent that the P-51, even at Normal Rated Power, has a clear airspeed advantage and has equivalent climb to the Bf-109G form SL to ceiling. If my data on the Bf-109G is incorrect, let me know, I will gladly correct my data base.
WEP was not like a afterburner. MW50 and Military power was like that, cause it could get used in climb and even close combat, not so WEP, at least not withut to fear trouble within a few mins.
Emergency, that normaly means, if you be in danger and that normaly means, if you want to get away, not if you make a sustained turn or climb to get onto the enemys tail.
I disagree with this. Both are handled similarly in combat. The main difference is that, while the engine may fail if you over use WEP, more likely you may have to work on the engine when you get back. With overuse of the afterburner, the plane gets very quiet because it has run out of gas.
A burner flight in a T-38 consist of a burner climb (it had set a record to 40k in 90 sec) a Tacan arc around the base obtaining supersonic flight and a landing. The flight only took a few minutes and the plane was out of gas. It normally flew 1.2 to 1.5 hours.
drgondog said:Knegel - first, whether th Mustang was 20 km/hr slower or faster - it by and of itself only mattered in a chase.
I have a slight disagreement here. Airspeed advantage helps in control of the fight, whether to fight or not, and, of course if not, like you run out of ammunition, to flee. Also, airspeed advantage equals energy advantage. Two aircraft engaging head on, one at 400 mph and one at 420 mph, the plane flying at 420 mph has an energy advantage, which is important.
jim said:2) The theory of "local american numerical inferiority" and P51 fightinng in" poor odds" is truly amazing.
Helmut Lipfert wrote: There were so many fighters above the bombers that i did not dare to look upwards.
Also: He also writes that p51 was less dificult than Yak 3 but the main problem was that was always appearing in Huge numbers
Reschke: Every german fighter was attacked by 10 allied fighters
August Labert was killed in April 1945 when he and his staffel were jumped by 80(!!!) mustungs .Oesau was killed in may 1944 after fighting alone with many escort fighters .And he was a Kommodore! Not any pilot. P51 always had both height advantage and numerical advantage. Even if there were many german fighters they were enganged with the bombers . The high escort was terribly outnumbered . Additionally the lack of capablle leader formations made things worse because was difficult to form huge battle groups.
I think this has been argued more effectively in other threads. I think the main argument was that early in '44 when the Mustang was making itself known, there were not enough to overpower the Germans with numbers and yet still dominated the sky over Germany. I am sure these comments were true in late '44 and '45, although this certainly was not the case at Y-29 in January '45 (we have a member whose father was a Mustang pilot there that day and became an ace).
3) P47 was unsuited for classic dogfigts. Boom and zoom was its forte. Killed Philips, Mayer ,Ubben, Galland by surpising bounce while they were occupied organizing attacks in bomber boxes . F4U1 and F6F3 were truly unsuited for escort fighters ( single stage supercharger) P38 besides its tecnical problems according to german pilots (eg Heinz Bar) was not that difficult to beat when engaged in reasonable odds
Nothing wrong with boom and zoom. An analysis by military, Navy, AAF, Brits, and company pilots in 1944 selected the P-47 as the best allied fighter above 25k ft.
4) P51 appears to be a truly magic machine . Using a low drug wing has the range , speed (even at low level where its two stage supercharger should be in disadvantage), dive, but at the same time can outclimb
In June, 1944, the P-51B at full rated power and fighter weight was capable of around 386 mph at SL and a climb of 4400 ft/min, and could hit 445 mph at altitude, this is per test. Only very late did Germany develop aircraft that would outclass it. From its onset in late 1943, the P-51B/D took the war to the sky over Germany, flying hours at a time and then going head-to-head with Germany best planes and then flew hours to get home. It certainly was a miracle cure for the Eighth AF.
and out accelarate aircrafts with better power loading and high lift wings
I'm not sure anyone has said that except the less informed. Of course efficiencies come into play also.
,(and dont forget Bf 109 had not "laminar flow " wing but was a smaller airframe)
The Bf-109 was not noted as a very clean machine until the K came along.
Its amazing not only in comparison with german aircrafts but british as well . Sea Fury reaches 460mph with 2400hp ,P51h 487 mph with 2218hp .F4U5 needs 2500hp for 460mph(on corsair please correct me if i am mistaken)
Big radials require big area require big power.
Okay, p51 is smoothier. Spitful XIV on 2375 hp from Griffon 85 tops at 478mph with its new "laminar flow wing" and its smaller, P51h 487mph on 2218hp .
Probably realistically 475 mph. 487 mph was an engineering estimate and a two to three percent estimate error would cover that. But who knows maybe it could have.
At the same time P51h outcimbes SeaFire 47 wich has 2350hp from Griffon 88 , six blade contra prop propeller and the old ( not the very old) high lift wing!!!
The Spitfire was not as efficient as the P-51. The P-51 with the same merlin as the Spit, was 30 mph faster at SL (as I've read somewhere).
All fighters reported hadling worsening as more and more power was added and strengthening was nessesary. P51h added power, Lost weight and Usaaf claimed in its official manual to be 10% stronger than P51D (Truly Mr Drongong said that propably thiis a mistake)Also it has 12,7mm guns that reportetly knocked out Tiger tanks when german used for the same purpose 30mm,37mm ,50mm ,75mm,the British 40mm, the russians 23mm,37mm. I admit that the comparison of speeds is somewhat crude for the luck ofprecise altitude , I write from memory
I think these claims are just uninformed prattle.
In spite of the constant ramblings about the P-51 not being strong, was only effective in mass groups, was good only at high altitude, ad infinitum, it was a fast, formidable fighter from sea level to ceiling that could uniquely perform at four hundred miles and return with pilots that had confidence in its capabilities and which spelled an early doom to the Third Reich.
Hi,
you shouldnt forget that the Speed of the P51 is always given with WEP, while the speed of the 109G without MW50 is mainly with combat climb!!
Since late 1943 the 109G also had WEP available. Specialy regarding the P51B in 1943( -3 engine) you will find that it was not faster than the clean 109G-1/2 + WEP between 5500 and 7000m and i guess the P51b without WEP wasnt faster there as well. And specialy in high alt speeds was fast much below Vmax.
The clean 109G made around 640km/h on combat climb and + 20-30km/h on WEP. Thats what the P51B mase in around 6000m, also with WEP.
The climb of the clean 109G-1/2 was as good or better than that of the P51B/D up to 6000m, all over rather similar. Once again you should look to combat climb, not the WEP test.
Dont look to the late war climb datas of the MW50 powered engines, cause this combat climb datas are with less power than the early DB605A, while they also could climb with Sonder-Not(MW50), unfortunately there are only a few climb tests made with this setting, and i never saw a good one(with background datas).
The 109 had clear handling advantages in high alt(mainly rather slow speeds IAS), but anyway, thats later.
btw, nowhere i wrote 150 Octan fuel dont got used.
Hi,
the FW190A wasnt a failsure in the design, but in combination with its engine it was a failsure for the home defence, which took place mainly in high alt. As i wrote, they should have use the C3 fuel for the 109´s to allow them to fight on even therms with the escort, then, more close to the target, all other heavy armned fighters could have done their job. Strangewise there was not a single complete JG or even Gruppe in late 43/early 44 to fight only the fighters.
They realy thought its enough to keep the escort buisy, with a few top cover fighters, they dont saw the need to destroy the fighters. Bad mistake.
True - very bad mistake at the early stages but probably ok as the skill levels of the LW deteriorated.
Lipfert, same like Hartmann fought only short time in the home defence, but what they describe fit exact to what other home defence unit pilots wrote.
If you compare the defenses strength of LuftFlotte Reich, combined with LF3 on the Channel, versus LF2, LF4 and Kdo Dud Ost it is clear that the east and south defenses were much weaker... By the same token the 12th and 15th AF only had 1/2 the fighter strength of the 8th AF.
The JG302 also fought long time mainly vs the 15th airforce, comming from Italy, still it was home defence.
I only know a few storys where P51´s got into a bee swarm of 109´s, while there are hundrets of storys where single german fighters got hunted down by many P51´s.
I can give you many examples but I will start with these and let You research the German forces applied to these areas on theses dates.
March 6, 1944 (4th and 357th FG in Berlin to Brandenburg areas
March 8 (4th FG in Berlin to Magdeburg)
March 16 (4th, 355th, 357th FG) in Stuttgart, then Augsburg, then Munich and back to Ludwigshafen)
March 29 (4th and 355th in Brunswick to Uelzen to Gifhorn area)
April 8 (4th FG and 354th FG in Brunswick to Celle to Uelzen area)
April 11 (357FG in Hannover to Brunswick to Magdeburg to Leipzig area)
Aprill 22 (4th FG SW Kassell)
April 24 (355th and 357th FG in Ulm to Augsburg to Erding to east and southeast and south and southwest Munich area)
May 8 (352nd FG in Bremen to Brunswick to Celle area)
The reason I use these is because this was the time period when only three to five Total Mustang groups were escorting at the target area - and none of the P-38 (0r P-47) groups were anywhere near these targets.
In each and every example the 8th AF tactics were to send flights of four or sections of eight to attack large German forces from each squadron - as they saw them - and retain the rest as escorts until another strong German force was encountered. It is a common mistake to believe that 8th AF standard practice was to 'send many after a few' as there were only a few Mustangs (like one Group of 30-50 fighters to cover 500 bombers along a 20-30 mile trail in these ealy battles deep in Germany.
The tactic to run away, using a split S to get away was mainly caused by inexperienced pilots in overloaded fighters. A 109G with 30mm´s under the wing wont manouver very good in high alt, specialy not alone(wingi lost after the attack to the bombers) vs severel enemys out of a disadvanced position.
But often repeated with fatal consequences - Rall was fortunate to escape with his life in his own encounterattempting to dive away from escorts.. not exactly 'inexperienced'
Many pilots of the home defence units was unexperienced, in case of the JG30x, the pilots dont had any fighter combat training, most pilots was bomber pilots, educated to fly and navigate at night.
The tactics used so successfull since spain couldnt get used anymore, thistactics was good for escort and sweeps, if you get the order to intercept the bombers instead, its just a holeless task.
To a degree true, but more true after May 1944 when the February-May attrition on LufFlotte's Reich and 3 were so high
Herr Meyer(former Göring) and his Ostmark idol was just to stupid, if they dont listen to their experienced fontline leaders, even the best pilots and planes cant win.
Greetings,
Knegel
I am a bit confused by what you have said here but I can be slow. I will confess that I have limited data on the Bf-109 so I can't argue your points knowledgably. So, lets assume my data for the Bf-109G is at combat rating, that is, no water injection or WEP. This is a comparison, right or wrong. Power settings for the P-51B(-3 engine) is at 60" (close to Normal Power) and the P-51B(-7 engine) is at 67" combat power. These data are from AAF flight test with aircraft tail number and weight identified. Note: The -3 engine P-51 is a couple hundred pounds under fighter weight, which would affect climb. The -7 is at fighter weight.
SL a/s(mph) climb rate(ft/min)
P-51B-3 348 3600
P-51B-7 357 3780
Bf-109G 326 3678
10k ft
P-51B-3 386 3540
P-51B-7 407 3310
Bf-109G 362 3060
20k ft
P-51B-3 424 2915
P-51B-7 427 3080
Bf-109G 399 3094
25k ft
P-51B-3 427 2600
P-51B-7 440 2350
Bf-109G 397 2240
30k ft
P-51B-3 441 2250
P-51B-7 429 1600
Bf-109G 400 1625
It is apparent that the P-51, even at Normal Rated Power, has a clear airspeed advantage and has equivalent climb to the Bf-109G form SL to ceiling. If my data on the Bf-109G is incorrect, let me know, I will gladly correct my data base.
I disagree with this. Both are handled similarly in combat. The main difference is that, while the engine may fail if you over use WEP, more likely you may have to work on the engine when you get back. With overuse of the afterburner, the plane gets very quiet because it has run out of gas.
A burner flight in a T-38 consist of a burner climb (it had set a record to 40k in 90 sec) a Tacan arc around the base obtaining supersonic flight and a landing. The flight only took a few minutes and the plane was out of gas. It normally flew 1.2 to 1.5 hours.
I have a slight disagreement here. Airspeed advantage helps in control of the fight, whether to fight or not, and, of course if not, like you run out of ammunition, to flee. Also, airspeed advantage equals energy advantage. Two aircraft engaging head on, one at 400 mph and one at 420 mph, the plane flying at 420 mph has an energy advantage, which is important.
The allied HQ wasnt as stupid as the german HQ, when they started the bomb raids again in early 44, there was already enough mustangs available to outnumber the german topcover, if there was one at all, in big degrees and the other heavy armned fighters wasnt dangerus for them anyway.I think this has been argued more effectively in other threads. I think the main argument was that early in '44 when the Mustang was making itself known, there were not enough to overpower the Germans with numbers and yet still dominated the sky over Germany. I am sure these comments were true in late '44 and '45, although this certainly was not the case at Y-29 in January '45 (we have a member whose father was a Mustang pilot there that day and became an ace).
Nothing wrong with boom and zoom. An analysis by military, Navy, AAF, Brits, and company pilots in 1944 selected the P-47 as the best allied fighter above 25k ft.
Thats not full rated power, thats WEP.In June, 1944, the P-51B at full rated power and fighter weight was capable of around 386 mph at SL and a climb of 4400 ft/min, and could hit 445 mph at altitude, this is per test. Only very late did Germany develop aircraft that would outclass it. From its onset in late 1943, the P-51B/D took the war to the sky over Germany, flying hours at a time and then going head-to-head with Germany best planes and then flew hours to get home. It certainly was a miracle cure for the Eighth AF.
The 109F, G1, G6-AS , G10 and K was known as very clean plane. Actually only the G-6 and G-14 was known to have to many bubbles.The Bf-109 was not noted as a very clean machine until the K came along.
At same time the Spitfire did climb 1000-1500ft/min faster.The Spitfire was not as efficient as the P-51. The P-51 with the same merlin as the Spit, was 30 mph faster at SL (as I've read somewhere).
In spite of the constant ramblings about the P-51 not being strong, was only effective in mass groups, was good only at high altitude, ad infinitum, it was a fast, formidable fighter from sea level to ceiling that could uniquely perform at four hundred miles and return with pilots that had confidence in its capabilities and which spelled an early doom to the Third Reich.
...
And if we then take a clean 109G1(3040kg) we get this with combat and climb:
G1
SL 4100ft/min 326mph
10k 3850ft/min 362mph
20k 3100ft/min 398mph
30k 1633ft/min 398mph
With WEP the plane had around 150PS more power at SL and 125 at rated alt.
...
1) german controllers were not that good. Josef Priller of JG26 often ceased operational flyinng in order to assume Jafu leader duties due to lack of talent of other persons. Reschke reports that many times ground control was poor , even disastrous . 14/1/45 led JG301 directly in front and under P51s . 29/12/44 ordered III/JG54 to patrol just un der the known patrol height of RAF fightters with disastrous results.17/8/43 failed to notice the presence of 56 fg so II/JG26 was surprised (and Galland died) Many times scrabled fighters early or late. You can find many examples in many books. Actually it was the exception when the system worked perfectly .
For every example you care to mention, I will cite several others where the LW controllers performed very well - just a few include March 6, April 13, April 24, April 29, May 12 when the relative numbers of escorts were inferior to the LW strength at the point of attack. In later times July 7, Sept 12, Sept 27, Nov 2 and 26 were examples of skillful direction to find weakly defended bomber formations.
As to Jan 14, 1945 I have no insight to the mistakes made by LW controller, but they DID position JG310 to attack the bomber stream where only one Mustang Group was present. The unfortunate circumstance was that it was one of the very best Allied Fighter Groups - the 357th FG
2) The theory of "local american numerical inferiority" and P51 fightinng in" poor odds" is truly amazing.
See my note to Knegel above regarding the early Mustang encounters with Luftwaffe and perform your own research to decide whether the US or LW had the most fighters in those battles in those areas.
Helmut Lipfert wrote: There were so many fighters above the bombers that i did not dare to look upwards.
Also: He also writes that p51 was less dificult than Yak 3 but the main problem was that was always appearing in Huge numbers
Reschke: Every german fighter was attacked by 10 allied fighters
With all due respect Reschke was simply wrong. Specific example November 26, 1944 around Misburg/Hannover. There was one Fighter Group which blunted JG301, JG1, JG 6 attacks by approximately 200 Fw 190s and Me 109s. Specifically 43 Mustangs in the 355th FG plus 7 from 2SF. Further to the east, near Gardelegen was the 361st and from SW Hannover to Dummer Lake the 339th FG arrived.
For Reschke to be remotely plausible, the 355th FG would have to have ~ 2000 Mustangs. If All THREE of the Groups had been in between the 2 BD B-24s bombing Hannover there would have been a ratio of 1 US fighter to 2 LW fighters. Look up the details.
Look up the air battle around Munich on 24 April and detail the strength of the LW fighters versus the two US groups (355th and 35th).. That ratio was less than 1:2
Last but not least recall the strength of US long range escorts from Dec 1943 through May 1944 - If ALL were concentrated in one specific location they would represent 1/2 of Luftflotte Reich. Using Willi's analogy the LW would have to attack ALL of the 8th AF P-38s and Mustangs with 25 fighters to make his silly claim true?
August Labert was killed in April 1945 when he and his staffel were jumped by 80(!!!) mustungs .Oesau was killed in may 1944 after fighting alone with many escort fighters .And he was a Kommodore! Not any pilot. P51 always had both height advantage and numerical advantage. Even if there were many german fighters they were enganged with the bombers . The high escort was terribly outnumbered . Additionally the lack of capablle leader formations made things worse because was difficult to form huge battle groups.
Jim - politely that is bovine fecal matter relative to first hand accounts. It is simply impossible to place more than one, maybe two squadrons of an escort in a volume of space to attack one squadron of German fighters. A US Fighter Group in May 1944 would be escorting ~ 2 combat wings, sometimes three - or 90-150 bombers stretched out over at least 15 miles. Often the squadrons were not even visible to each other.
Saying that '80' attacked the Labert's squadron would mean that his squadron simultaneously attacked two Complete strength Mustang Groups over a 20+ mile span of operations?
And No, Mustangs did Not have both heighth and numerical advantage. If you will study the Strengths and the Mission Summaries of the 8th AF you will find more examples of LW entering combat with a heighth advantage if the Controller and fighter leader had any brains! The Mustangs typically would position the lead squadron high (~2000 feet over the bombers), and one center weaving back and forth, and one trail. Later in the war, the two trailing squadrons might position on either side near the end of their assigned bomber stream.
The LW pilots were NOT stupid. They didn't come in at a level altitude, they came in high and went into a shallow dive - often company front (either head on or from trail), made one pass and split ess. The 109 'escort' Always came in at 30,000+ where the Mustangs were at 24-28000 depending on whether escorting B-17s and B-24s.
3) P47 was unsuited for classic dogfigts. Boom and zoom was its forte. Killed Philips, Mayer ,Ubben, Galland by surpising bounce while they were occupied organizing attacks in bomber boxes . F4U1 and F6F3 were truly unsuited for escort fighters ( single stage supercharger) P38 besides its tecnical problems according to german pilots (eg Heinz Bar) was not that difficult to beat when engaged in reasonable odds.
All anecdotal observations from the 'winner'. The losers were dead and unable to comment on the skill and quality of the fighter that killed him. I know an equal or greater number of P-51 pilots that are certain they could always out turn and out race both the 109 and 190.. simply because they didn't lose to one.
4) P51 appears to be a truly magic machine . Using a low drug wing has the range , speed (even at low level where its two stage supercharger should be in disadvantage), dive, but at the same time can outclimb and out accelarate aircrafts with better power loading and high lift wings ,(and dont forget Bf 109 had not "laminar flow " wing but was a smaller airframe) Its amazing not only in comparison with german aircrafts but british as well . Sea Fury reaches 460mph with 2400hp ,P51h 487 mph with 2218hp .F4U5 needs 2500hp for 460mph(on corsair please correct me if i am mistaken) Okay, p51 is smoothier. Spitful XIV on 2375 hp from Griffon 85 tops at 478mph with its new "laminar flow wing" and its smaller, P51h 487mph on 2218hp .At the same time P51h outcimbes SeaFire 47 wich has 2350hp from Griffon 88 , six blade contra prop propeller and the old ( not the very old) high lift wing!!! All fighters reported hadling worsening as more and more power was added and strengthening was nessesary. P51h added power, Lost weight and Usaaf claimed in its official manual to be 10% stronger than P51D (Truly Mr Drongong said that propably thiis a mistake)Also it has 12,7mm guns that reportetly knocked out Tiger tanks when german used for the same purpose 30mm,37mm ,50mm ,75mm,the British 40mm, the russians 23mm,37mm. I admit that the comparison of speeds is somewhat crude for the luck ofprecise altitude , I write from memory
Agreed - and back to our discussion - aircraft close to equal, poor tactics and leadership from Goering and Hitler, enormous attrition in the Battle of Germany (air), attacks on Petroleum/Chemical, poorly trained recruits, loss of keey Geschwader, Gruppe, Staffel and Rotte leaders in piles during first half of 1944
All made discussions about the relative 'superiority/inferiority of the fighters somewhat meaningless.
A few points on comparisons;
WEP is only available below rated altitudes. At rated altitude the supercharger is maxed out and cannot supply anymore air. At several thousand feet below rated altitude the air is a little denser and the supercharger can supply more air and the lower you go the the denser the air gets and the more air the supercharger can supply. This is where the WEP rating comes from. Up to the limits of the engine.
Speed and climb of Mustang vs Spitfire:
Speed is thrust vs drag. Mustang wins.
True for same Hp between the Merlins, given same low blower/high blower characteristics between the engines.. and generally true across all comparable period models - having said that the thinner wing of the Spit gave it a higher Mcrit speed.
Climb is excess thrust vs weight after a certain flight speed is reached. A lighter but higher drag aircraft can easily out climb a heavier but lower drag aircraft.
Not to forget - Wing area/lift loading a very important factor - Spit wins hands down except in certain zoom climbs where the KE of the Mustang combined with lower drag makes it close.
Another thing is that climb rates were usually established at speeds below 200mph where the drag is 1/4 the drag at 400mph so the amount of power going to drag is not going to be that far apart for the two aircraft.
Strictly speaking, 'hard to say'. The parasite drag of the 51 was less than a Spit and the induced drag on a Spit was lower than a 51. The drag buckest per se probably had a 'minimum drag point' distinctly separate from the other but probably withing 20mph of each other and probably within 10% at that low drag point (speculation as I don't have a drag polar for either ship)
Some of the German power boosting systems also had limits. it may not have been 5 minutes (although some early versions on 601s had a clockwork device that limited it to ONE minute)
The 1946 Jane's (which may not be accurate) gives the following for MW50
"...used to obtain extra power below rated altitude of the engine.."
"..increased power could be used for a maximum of 10 minutes at a time, and at least 5 minutes had to elapse between succesive periods of operation. At this increased power the sparking-plugs had a life of 15 to 30 hours."
"on the 109, injection into the supercharger of the DB605AM engine was at the rate of of approximately 35 gallons per hour. The normal fuel consumption at the take-off rating was 106 gallons per hour,but this was increased to 141 gallons per hour when using the MW 50 system with higher boost pressure"
The C3 injection system only increased power below the rated altitude.