Spitfire XIV vs Bf-109 K-4 vs La-7 vs Yak-3

[Kryten]

""Accept the lies of WW2 Aircraft performance and leave Mr Kurfust alone!""

pot kettle black mate, best work from a position of balance before you make statements like that!

 

[Shortround6]

a technical question Is it possible an aircraft with equal power and less total wet area than another plane to be slower?

Yes, quite possible as "total wet" area is just one component of drag.

Others are

Frontal area.

induced drag, the drag created by the wing in producing lift. Different airfoils and wings have different lift to drag ratios.

general shape and/or interference drag. Changing small items (windscreens, exhaust outlets and such) can make a difference. Classic is the bullet proof windscreen on the Spitfire, worth 6mph. Didn't change the frontal area, didn't change the slope of the windscreen (overall shape), increase the "total wet area" by it's perimeter and thickness? It did change the airflow around the canopy due the square edges disturbing the airflow. Also check wing root fillets on many aircraft. They increase "total wet area" but decrease the interference drag at the fuselage/wing joint.

I am sure that there are other components of drag I have left out.

Another question is are you sure that both aircraft actually have "equal power"? propeller shaft horsepower is not thrust and thrust is what makes speed. Any difference in propeller efficiency? any difference in exhaust thrust?

 

[Juha]

...
For people with proper judgement his work on his site speaks for itself.

I wrote that Kurfürst's site is excellent, You disagree?

a technical question Is it possible an aircraft with equal power and less total wet area than another plane to be slower?

Now 109K-4 was faster than Spit XIV at low and middle altitudes when using MW-50 but high up Spit was faster.

 

[Vincenzo]

I also had crossed swords with Kurfürst and I also be careful with his claims but his site is excellent and for ex in his 109K specs part he correctly points out that in the graphs the thick lines are results of calculations by Mtt for 109K with an experimental thin blade airscrew and that the most important graph is the thin line which is that of 109K-4 with standard airscrew and he also notices that the compression effect was ignored in the calculations.

Juha

Where he notices that the compression effect was ignored?
imho that curves not ignore the compression effect.

 

[Vincenzo]

On the page uploaded from Aozora
i'm not agree that DB 605 non offered better performance of DB 601, also w/o emergency power the DB 605 can use the 30 minutes setting that give aroun the same power of DB 601 in emrgency power so it's clear the DB 605 give better performance

 

[DerAdlerIstGelandet]

Knock this **** off!

1. Kurfurst is not here to defend himself. Be an adult and don't insult someone who can't defend themselves. You guys act like a bunch of damn children sometimes!

2. Quit your insults to each other! Grow the hell up!

One more insulting remark from any member, and all members involved will get some time off. I don't care who started it. I am so sick and tired of this trivial BS! I know toddlers that act more mature. How many times do we have to do this?

Now get back on topic.

 

[Tante Ju]

On the page uploaded from Aozora
i'm not agree that DB 605 non offered better performance of DB 601, also w/o emergency power the DB 605 can use the 30 minutes setting that give aroun the same power of DB 601 in emrgency power so it's clear the DB 605 give better performance

I agree. DB 605A even with 30 min rating seem to offer better performance than 601E at max rating.

 

[Juha]

Where he notices that the compression effect was ignored?
imho that curves not ignore the compression effect.

It is my interpretion of the fact that Mach effect wasn't taken into account.

Juha

 

[Aozora]

On the page uploaded from Aozora
i'm not agree that DB 605 non offered better performance of DB 601, also w/o emergency power the DB 605 can use the 30 minutes setting that give aroun the same power of DB 601 in emrgency power so it's clear the DB 605 give better performance

I have no doubt the DB 605 was more powerful than the DB601E - Mankau and Petrick made the point that until initial problems with the DB605 were solved the use of emergency power was forbidden, thus limiting the maximum power. Without seeing the relevant power curves for the DB605 v DB601E how are we to know?

What is more important - and my question was - in light of the changes made to the 605 design versus the 601, and the general concerns of the RLM over the DB605, how reliable was the DB 605 by the time the K-4 got into service, particularly with the steep decline in build quality/possible sabotage and shortages of important metals? It also needs to be noted that in late October 1944, because of constant attacks on the oil industry, aviation fuels were in short supply, so much so that Luftwaffenkommando West ordered that operations be curtailed:

On top of which, on 2 November, the USAAF attacked more oil targets with 1,100 bombers...

Was this order ever rescinded?

 

[Vincenzo]

It is my interpretion of the fact that Mach effect wasn't taken into account.

Juha

As is well known i've not technician formation but i've the impression that mach effect and compressibility error are not the same, i hope some can give educated info.

 

[tomo pauk]

My 2 cents:
DB-605 of 1944 was far more reliable than in 1943 or 1942. DB has made many of changes required that 605A functions well even in the confines of the small airframe, and we do not encounter any restrictions after late 1943, for the 605. Since the engine power was pushed to 2000 PS in 1945, the engine reliability seem okay. Despite the increasing difficulties for the German armament industry all together.
If the RLM was concerned over reliabilty of the DB-605A, that might apply for the time before late 1943?

 

[wuzak]

As is well known i've not technician formation but i've the impression that mach effect and compressibility error are not the same, i hope some can give educated info.

It is my understanding that the Mach effect causes compressibility.

 

[Aozora]

My 2 cents:
DB-605 of 1944 was far more reliable than in 1943 or 1942. DB has made many of changes required that 605A functions well even in the confines of the small airframe, and we do not encounter any restrictions after late 1943, for the 605. Since the engine power was pushed to 2000 PS in 1945, the engine reliability seem okay. Despite the increasing difficulties for the German armament industry all together.
If the RLM was concerned over reliabilty of the DB-605A, that might apply for the time before late 1943?

Mankau and Petrick seem to have seen records which led them to a different opinion. Is there any evidence to show that the DB 605 of 1944 was more reliable, and, if so, what evidence? It is all very well quoting test bed performance figures, but operational reliability under adverse conditions can be altogether different.

 

[CobberKane]

Up about 2000 m altitude - no. Above - yes.



Tempest is about as fast as La 7, faster than Yak 3. Both run circles around it though..

By 'run circles around' do you meant the Soviet fighters could out-turn the Tempest, or that they comprehensively outclassed it?

 

[Shortround6]

It is all very well quoting test bed performance figures, but operational reliability under adverse conditions can be altogether different.

yes it can, Both Merlin and Sabre engines had very short lives in adverse conditions while the Merlin engines in bombers were rated at 360 hours in 1944 and in transports at 480 hours. Forward fighter fields can be very dusty/dirty places and without very good filters they can destroy engines in short order but that is a different sort of failure than burning piston crowns or valves or other signs of local overheating or operational problems (oil foaming)that will exist regardless of the amount of dirt the engine swallows.

While engine failure records are interesting, unless they breakdown the kind of failure or cause, they really don't tell us if the engine was reliable or not. A Merlin in 1939 in a fighter was supposed to be good for 240 hours flying from English sod airfields, Flying out of Malta or in NA engines many times didn't last 100 hours. It doesn't mean the 1941/42 Merlins were less reliable. It means the conditions were really adverse.

 

[Aozora]

yes it can, Both Merlin and Sabre engines had very short lives in adverse conditions while the Merlin engines in bombers were rated at 360 hours in 1944 and in transports at 480 hours. Forward fighter fields can be very dusty/dirty places and without very good filters they can destroy engines in short order but that is a different sort of failure than burning piston crowns or valves or other signs of local overheating or operational problems (oil foaming)that will exist regardless of the amount of dirt the engine swallows.

While engine failure records are interesting, unless they breakdown the kind of failure or cause, they really don't tell us if the engine was reliable or not. A Merlin in 1939 in a fighter was supposed to be good for 240 hours flying from English sod airfields, Flying out of Malta or in NA engines many times didn't last 100 hours. It doesn't mean the 1941/42 Merlins were less reliable. It means the conditions were really adverse.

Yep, and the British developed and used filters for both the Sabre (very quickly, in the case of French based 2TAF Typhoons) the Merlin and the Griffon, as did the Americans for the Packard Merlin and the Germans for the DB 605.

In view of the comments of Mankau and Petrick (who have read original documentation) I am trying to pin down whether the DB 605, especially the DB/DC series, had inherent design faults which were never fully resolved. So far there has been nothing concrete showing that the final versions of the 605 could reliably develop the 2,000 PS, often cited, in operational service, especially when Allied bombing meant that there were shortages of all grades of avgas and a lack of methanol for MW50. Because of these factors I have serious doubts over whether the majority of K-4s in operational service could reach their full performance potential because they were more than likely restricted to using B4 grade fuel without the benefit of MW50.

 

[tomo pauk]

Mankau and Petrick seem to have seen records which led them to a different opinion.

Let's assume they have seen the records. What are these records saying for the DB-605A for 1942, 1943, early 1944, late 1944? Eg. Napier Sabre was in shambles in 1942, but far less in 1944.

Is there any evidence to show that the DB 605 of 1944 was more reliable, and, if so, what evidence? It is all very well quoting test bed performance figures, but operational reliability under adverse conditions can be altogether different.

In search for the records, one might go to BA-MA and check out for himself.
We know that Notleistung was banned between late 1942 and late 1943, until the DB solved the issues by having a proper de-aerator installed in the lubrication system. After late 1943, there are no issues mentioned about the DB-605A having any issues. The DB-605ASM, in mid 1944, goes to 1800 PS. In my book, that means the engine is reliable.
Operating the engines under the adverse conditions does not provide benefits for any engines, again there is no point to single out the 605 here. You can note that ex-Yu air force was operating the BF-109s (G-2 to G-10 G-12(two-seater)) into the 1950s, and those were received as second-hand planes, mostly from Bulgaria.

...

In view of the comments of Mankau and Petrick (who have read original documentation) I am trying to pin down whether the DB 605, especially the DB/DC series, had inherent design faults which were never fully resolved.

As for Mankau Petrick, applies what I wrote above. Talking about the 'inherent design faults' for the DB-605 family is eggrageration.

So far there has been nothing concrete showing that the final versions of the 605 could reliably develop the 2,000 PS, often cited, in operational service, especially when Allied bombing meant that there were shortages of all grades of avgas and a lack of methanol for MW50. Because of these factors I have serious doubts over whether the majority of K-4s in operational service could reach their full performance potential because they were more than likely restricted to using B4 grade fuel without the benefit of MW50.

If there was C3 and MW50 around, why not? Why questioning the capability of the DB-605D to 'reliably develop' the 2000 PS, if the pre-requisites (availablity of C3 and MW50) could not be met? Those are not the 'inherent design faults'. No R-2800C, turbo, will make 2800 HP without 130 grade fuel and ADI, same applies for DB-605D. The R-2800C running on 87 oct fuel, no ADI, can make what, 1800 HP?

 

[Tante Ju]

By 'run circles around' do you meant the Soviet fighters could out-turn the Tempest, or that they comprehensively outclassed it?

Yes I mean they were much more manouverable in rolling and horizontal plane (the La 7 was also very fast, about as fast Temptest, depending on test). Not on all acounts of course, Tempest was very good plane, and very versatile. IMHO easy best British fighter of war. Good armament, good range, good cocpit, fast and acceptable maneuverability.

Mankau and Petrick seem to have seen records which led them to a different opinion. Is there any evidence to show that the DB 605 of 1944 was more reliable, and, if so, what evidence? It is all very well quoting test bed performance figures, but operational reliability under adverse conditions can be altogether different.

So far there has been nothing concrete showing that the final versions of the 605 could reliably develop the 2,000 PS, often cited, in operational service, especially when Allied bombing meant that there were shortages of all grades of avgas and a lack of methanol for MW50. Because of these factors I have serious doubts over whether the majority of K-4s in operational service could reach their full performance potential because they were more than likely restricted to using B4 grade fuel without the benefit of MW50.

You are guessworking... if you have data about showing reliability of these engines (or lack of it), please share them. Saying 'there is no evidence to the contrary of what I say' is logic flawed - if I read Mankau, they qoute German meetings, yes until about late 1943 there is lot of meetings about DB 605 reliability but afterwards I cannot really find. I suppose it has been fixed with lubrication system fixed.

And why were K-4s more likely restricted to fly with B-4 fuel? And why K-4 especially - because its best 109? There are plenty of examples of late war 109s flying C-3 on Kurfurst site, so you have bring some more concrete to this table.

Lack of methanol too? First hear. Where you read this? Also methanol was not absolutely required - it was anti freeze agent. Even pissing into the booster tank would do nicely for boosting...

Also difference between B-4 109 or C-3 fuel 109 was not that great. Latter was faster by some 10-15 km/h at low altitudes looking at graph.

Maybe you have some real information for your serious doubts. Sources, from which we can learn. I have seen most late war engines had very short practical life - 50 hours. Klimon, Merlin, Griffon Daimler, Sabre - doesnt really matter. Engines were pushed to extreme.

 

[cimmex]

.... there were shortages of all grades of avgas and a lack of methanol for MW50. Because of these factors I have serious doubts over whether the majority of K-4s in operational service could reach their full performance potential because they were more than likely restricted to using B4 grade fuel without the benefit of MW50.

where did you hear this, there was never lack of Methanol in Germany during WW II.
cimmex

 

[Aozora]

You are guessworking... if you have data about showing reliability of these engines (or lack of it), please share them. Saying 'there is no evidence to the contrary of what I say' is logic flawed - if I read Mankau, they qoute German meetings, yes until about late 1943 there is lot of meetings about DB 605 reliability but afterwards I cannot really find. I suppose it has been fixed with lubrication system fixed.

And where is solid data from you showing that yes, the DB605 was fully developed and reliable by 1944? I've presented published evidence from authors who have read the records, you've presented nothing but opinion.

And why were K-4s more likely restricted to fly with B-4 fuel? And why K-4 especially - because its best 109? There are plenty of examples of late war 109s flying C-3 on Kurfurst site, so you have bring some more concrete to this table.

Doesn't concern me whether the K-4 was best 109 or worst; all I'm asking is that people answer my questions with some solid information without turning this into a "pissing contest", or stupid accusations of bias over which was the better aircraft. Please point me to the "plenty of examples...on Kurfurst site" - I see tests, but nothing much to indicate operational K-4s in large numbers.

Lack of methanol too? First hear. Where you read this? Also methanol was not absolutely required - it was anti freeze agent. Even pissing into the booster tank would do nicely for boosting...

Maybe you have some real information for your serious doubts. Sources, from which we can learn. I have seen most late war engines had very short practical life - 50 hours. Klimon, Merlin, Griffon Daimler, Sabre - doesnt really matter. Engines were pushed to extreme.

Maybe you all have real information you can share about exactly how reliable the DB 605 was, or how much methanol was available to the Luftwaffe? Until such solid information can be presented then I'm perfectly entitled to express my doubts, just as you are entitled to your opinions.