WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov vs Jumo

[Knegel]

Originally posted by gripen
That is simply because the test data shows if an engine delivers claimed performance. Note that even the lowest performing Merlin 70 you choosed gave closer to specs performance than the tested DBs.
 

The problem with that is the chronic tendency of the DBs to not live up to the specs. Therefore test data gives better picture.



You brought in calculated data (accounts no drag rise due to compressibility) which you claimed to be flight tested.

Besides even the lowest performing Merlin 70 test data you choosed delivers higher output at high altitude than the calcudated data for the DBs.

Hi,

actually i didnt claim the K4 is flight tested, i took the only availabe K4 (DB605D) datas i know.

Testdatas with RAM only show, if a engine in the particular airframe delivers claimed performance.
Actually i never saw a DB605D test and the tested ASM seems to delivers claimed performance.



DB605ASM
FTH static
Sondernot: 6400m
Start/Not: 8000m
Steig/Kampf: 7800m


FTH RAM
Sondernot: 6800m  400m above static fth
Start/Not: 8700m(roundabout) 700m above static fth
Steig/Kampf: 8600m  800m above static fth


Merlin 70/V-1650-3:

Static FTH
combat/climb: 1055HP at 8231m
max power: 1380HP at 7100m( found a other source with 7450m),

FTH RAM of the three HF Spitfires:
8475m  (with a weight of 3218kg) 1025-1375m above static fth
8100m  (with a weight of 3218kg) 650-1000m above static fth
7743m  (with a weight of 3160kg) 300-650m above static fth

Dont look that bad for the AS.
 
Are there more datas to the GJ-FX test available?? Are this tested or calculated performences?
Are there any other tests available?

Even if we reduce the GJ-FX speed by 40km/h, in 9000m its still as fast as the slowest Spit in test, with 15km/h correction its still as fast as the fastest Spitfire, despite the smal weight of the Spits in test.

Once again i only see very similar performing engines.

All arguments against this currently base on assumtions, which are sooooo bad and wrong, if Kurfi use them.

Greetings,

Knegel

[gripen]

Originally posted by Knegel

actually i didnt claim the K4 is flight tested, i took the only availabe K4 (DB605D) datas i know.

You did (actually several times), your post 06-19-2007 06:47 AM:

"The 109K4 tests show..."

Originally posted by Knegel

Testdatas with RAM only show, if a engine in the particular airframe delivers claimed performance.

The flight test data for the Merlin shows quite steady RAM response and close to spec performance:

Static ratings for 2nd FTH at WER from RR specifications (note that aircraft cards contain a lot of errors on ratings):
V-1650-3 1330hp at 23300ft
Merlin 70 1475hp at 22250ft

FTH with high speed RAM from the specs:
P-51B 29000ft (US spec)
P-51B 28000ft (UK spec)
HF IX 27500ft

Tested FTHs and difference to the spec:
AAF No. 43-6883 29400ft +400ft to US spec +1400ft to UK spec
FX953 28000ft -1000ft to US spec 0ft to UK spec
BS551 27800ft +300ft
EN524 26600ft -900ft
BS310 25400ft -2100ft (640m)

As for comparison the best performing AS plane (GJ+FX) was 700m below the spec at similar rating.
 

Originally posted by Knegel

Are there more datas to the GJ-FX test available?? Are this tested or calculated performences?
Are there any other tests available?

The GJ+FX data is flight tested, I have given the sources for other data above.

[Knegel]

Hi,

do you know other tested 109´s with AS engine, or why do you talk about the best AS plane??

And in your datas i cant see that the tested DB605AS RAM power FTH is below the Spitfire Merlin70, its also in a normal way above the static power.

The difference between the Spitfire and Mustang show how important the airframe was(for the RAm power), therefor its simply not good possible to compare the engines by the RAM power.

I cant see that the DB´s are below what they should do, therefor the static power are the datas to use to compare the engines.

Otherwise you compare the planes + engine.

Greetings,

Knegel

[gripen]

Originally posted by Knegel

do you know other tested 109�s with AS engine, or why do you talk about the best AS plane??

There is two other tested AS planes claimed above, the reached FTH was about 300m less than in the case of the GJ+FX at 1,3ata 2600rpm.

Originally posted by Knegel

And in your datas i cant see that the tested DB605AS RAM power FTH is below the Spitfire Merlin70, its also in a normal way above the static power.

The FTHs with RAM are discused here to check if the tested engines lived up to the specification. If the static power had been tested, the results would have followed the trend of the FTHs with RAM (the speed differences cause rather small variation as will be shown below).

The static FTH for the DB 605 ASM is 6400m in the specs and tested FTH with RAM in the best case was 6800m ie 400m increase due to RAM over the spec.

The static FTH of the Merlin 70 is 22250ft (6782m) in the specs and tested FTH in the worst case was 25400ft (7742m) ie 960m increase due to RAM (note that even using wrong values like you did above, the increase would had been 655m over the spec).

Originally posted by Knegel

The difference between the Spitfire and Mustang show how important the airframe was(for the RAm power), therefor its simply not good possible to compare the engines by the RAM power.

The best P-51B shows 1860m increase over the spec static FTH, the best HF IX shows 1690m over the spec FTH ie the difference 150m. Given that the difference between even the worst Merlin 70 and the best DB 605AS is in hunreds of meters (even using wrong values like you did ), it is obvious that the speed and RAM combinations does not make large error here.

[Knegel]

Hi,

i found one of the other tested AS engines(on Kurfis page), it was to new to fly with combat climb in low level, a to new engine is a good reason for a rather bad performence and the whole configuration was a prototype.

If the Merlin70 was so advanced, do you have a idea why the heavy wingloaded 109G14 did fly that fast in 9000m and why the K4 was even faster in a higher alt?

I already wrote that the DB605ASM with Sondernot had only a 400m higher RAM FTH  than static FTH, but on the other hand the Start/Not and Steig/Kampf FTH is good above the static FTH.
And the speedcurve of GJ+FX show a Sondernot FTH of 7000m, while they write 6800m on the right side.

The RAM effect dont have to be the same between different plane types.
Maybe the static power FTH´s are optimistic, but even with some hundret meters less, the power is pretty even to the static Merlin 70.
It also can be the other way around, the Spitfire airframe could provide a better RAM effect than the 109 Airframe, nevertheless the planeperformences show that the RAM power output must have been rather similar.

A US plane comparison show a static FTH for the V 1650-3 of 23300ft.

btw, iam absolutly not sure that the K4 datas with the default propeller are calculated. The calculation could be only related to the new propeller. At this time they should have had enough testdatas for the "normal" K4 to get around a calculation.

But of course we also could assume that all G10 and K4 datas in the comparison tables are only Nazi propaganda, based on horrible calculations, without to look to the tested datas they had.

Greetings,

Knegel

[gripen]

Originally posted by Knegel

i found one of the other tested AS engines(on Kurfis page), it was to new to fly with combat climb in low level, a to new engine is a good reason for a rather bad performence and the whole configuration was a prototype.

Pure speculation and the difference to the GJ+FX is not big.

Originally posted by Knegel

If the Merlin70 was so advanced, do you have a idea why the heavy wingloaded 109G14 did fly that fast in 9000m and why the K4 was even faster in a higher alt?

This thread is about engines. Bring in better documented and properly corrected data and start a new thread if you want to discuss about airframes.

Originally posted by Knegel

I already wrote that the DB605ASM with Sondernot had only a 400m higher RAM FTH  than static FTH, but on the other hand the Start/Not and Steig/Kampf FTH is good above the static FTH.

It's still below spec and even using the 30min power the best AS plane has lower RAM response than the worst HF IX at 5min power. Besides the output difference is even wider in that case.

Originally posted by Knegel

The RAM effect dont have to be the same between different plane types.
Maybe the static power FTH´s are optimistic, but even with some hundret meters less, the power is pretty even to the static Merlin 70.

Well, I quess you will try to twist numbers for ever but the spec output (1500ps at 6400m) does not make the AS even with the Merlin 70 at high altitude (1475hp at 6780m).

[Knegel]

Hi,

Originally posted by gripen
Pure speculation and the difference to the GJ+FX is not big.

Its not a speculation that a very new engine dont bring the power of a engine that did run the needed hours to be able to fly with full power.
And its no speculation that the engine was very new.

Originally posted by gripen
This thread is about engines. Bring in better documented and properly corrected data and start a new thread if you want to discuss about airframes.

Since we dont have many documents for the german engines, its imho needed and valid to take the available plane performences to estimate the engine performence.  

Originally posted by gripen

It's still below spec and even using the 30min power the best AS plane has lower RAM response than the worst HF IX at 5min power. Besides the output difference is even wider in that case.

Iam not realy sure if thats right, cause i think you dont use the right power settings and fth´s for the Merlin70. You use the 25lb boost power and FTH´s and mix them up with the tested 18 lib boost fth´s.

Originally posted by gripen

Well, I quess you will try to twist numbers for ever but the spec output (1500ps at 6400m) does not make the AS even with the Merlin 70 at high altitude (1475hp at 6780m).

Thats true, but i think the Spitfires and P51B got tested with this:





Greetings,

Knegel

[gripen]

Originally posted by Knegel

Its not a speculation that a very new engine dont bring the power of a engine that did run the needed hours to be able to fly with full power.
And its no speculation that the engine was very new.

The tested plane was faster than the GJ+FX at low altitude so there certainly was no large difference in output. Note that conditions in the GJ+FX data are slightly warmer than standard at FTH so the pressure altitude is lower than the density altitude.
 

Originally posted by Knegel

Since we dont have many documents for the german engines, its imho needed and valid to take the available plane performences to estimate the engine performence.  

As has been pointed out above, the tested engine performance (measured MAP and altitude) in the planes   show that even in the best case the output of the DB 605AS was well below the worst case Merlin 70 (or V-1650-3) at high altitude. Infact, even the worst Merlin 70 does higher output  than specification for the DB 605AS.

Bring in better documented and properly corrected data and start a new thread if you want to discuss about airframes.

Originally posted by Knegel

Iam not realy sure if thats right, cause i think you dont use the right power settings and fth´s for the Merlin70. You use the 25lb boost power and FTH´s and mix them up with the tested 18 lib boost fth´s.

I'm quoting +18psi values for the Merlin 70 directly from the RR specifications (can be found from "The Merlin in Perspective – the Combat Years" by A. Harvey-Bailey). And the test data discused earlier, list directly the altitudes and the corresponding MAP so there is no way to mix up the values.
 

Originally posted by Knegel

Thats true, but i think the Spitfires and P51B got tested with this:

Neither of the papers you linked is tested data nor the specification (note the 61"  MAP for the V-1650-3). Basicly you desperately throw in argument after argument regardless the sense of the argument.

[Knegel]

Hi,

61" MAP for the V-1650-3 is probably a typo, in the US plane comparison and in the tested datas you brought in the engine show a similar result with 67".

If the Spitfires Melin70 should have 1475hp at 6780m with 18lb boost, its MUCH below the specs in the test, not regarding the fth, but regarding the power.

At the current stage we dont have tested power datas for the Merlin70 in the Spitfire, neighter for the DB605AS or D, as result we cant get around to look to the plane performence to get an idea of the power output.
While the tested P51B power dont get close to 1475HP at hight and i have no doubt that the P51B airframe got more RAM power out of this engine.

To me it seems the Merlin 70 stand below its spec regarding the power, while the DB605 dont reach the FTH.

At the end the plane performences make me believe the engines was rather similar.
Where the AS was a bit below the Merlin70 and the D even up to 9000m, while its a bit worse above this.

Of course there is no exact prrof for this, but same there is even less a proof for a so much advances Merlin70 in the Spitfire like you say it was.

Therefor i dont see a sence to go on with this, until new datas appear.

Greetings,

Knegel

[MiloMorai]

The V-1650-3 and V-1650-7 got the RR designations M68 and M69 respectively.

blower gear ratios:
 
V-1650-3: 6.391:1 (low), 8.095:1 (high)

V-1650-7: 5.802:1 (low), 7.349:1 (high)

[gripen]

Originally posted by Knegel

61" MAP for the V-1650-3 is probably a typo, in the US plane comparison and in the tested datas you brought in the engine show a similar result with 67".

The specification static 2nd FTH values for the V-1650-3 are 1330/3000/23300 (hp/rpm/altitude) at +18,25psi. Note that the V-1650-3 is based on R.M.8.S.M. generation (Merlin 61) except the 12" impeller.

Originally posted by Knegel

If the Spitfires Melin70 should have 1475hp at 6780m with 18lb boost, its MUCH below the specs in the test, not regarding the fth, but regarding the power.

The specification static 2nd FTH values for the Merlin 70 are 1475/3000/22250 (hp/rpm/altitude) at +18psi. Note that the Merlin 70 is based on R.M.11.S.M. design ie it's later generation engine than the V-1650-3.

Basicly the Merlin 70 had lower 2nd FTH for a bit lower MAP but higher output. There might have been improved versions of the V-1650-3 but if you look power values from the AAF No. 43-6883 report, you can see that these follow quite close RR specs.

Originally posted by Knegel

At the current stage we dont have tested power datas for the Merlin70 in the Spitfire, neighter for the DB605AS.

There is 3 datasets on the Merlin 70 and 3 datasets on the DB 605AS. The output can be estimated fairly accurately based on MAP (error due to RAM is rather small).

[gripen]

Originally posted by MiloMorai
The V-1650-3 and V-1650-7 got the RR designations M68 and M69 respectively.

blower gear ratios:
 
V-1650-3: 6.391:1 (low), 8.095:1 (high)

V-1650-7: 5.802:1 (low), 7.349:1 (high)

Yes, the Merlin 70 had gear ratios 6.39:1 (low) and 8.03:1 (high) ie the high gear ratio was lower than in the V-1650-3. The 1st stage impeller of the Merlin 70 was improved if compared to the earlier generations. It's possible that later production V-1650-3s got improved impeller as well, the V-1650-9 had the same SC gear ratios and many features of the improved two stage Merlins.

[Knegel]

Hi,

Originally posted by gripen
There is 3 datasets on the Merlin 70 and 3 datasets on the DB 605AS. The output can be estimated fairly accurately based on MAP (error due to RAM is rather small).

So you realy  will sell that the Merlin70 had 1475HP in 27800ft??

Ok, lets see, the P51B had around 1370hp there, a similar wingarea, 1000kg more weight and a speed of 435-440mph.

While the Spitfire with 100HP more, but 1000kg less weight just reach 415mph(best case)??

The service ceiling of the P51B(42000ft) also wasnt that much below that of the Spitfire(43100ft, best case) to believe such a power advantage. The 1000kg more weight are already more than enough to explain that different and to make believe that the Merlin70 was rather less powerfull.

On the other hand the people claim that the Spitfire had the highest critical mach and the light wingload was a huge advantage in high alt.

Realy, if the Merlin70 had such a power output inside the Spit airframe, the SpitfireIXc airframe must have been the most worse in the war, or the tested planes all did fly with a damaged propeller.

Yae, the Spitfire was a plane full of miracles.

btw, it wasnt me who came up with the V-1650-3 power to discuss the merlin high alt performence.


Greetings,

Knegel

[gripen]

Originally posted by Knegel

So you realy  will sell that the Merlin70 had 1475HP in 27800ft??

I'm not selling anything, I merely quote the specification ie static output 1475hp at 22250ft for +18psi and 3000rpm. The real output with RAM depends on conditions, for one reason or another you refer now the FTH of the BS551 which still did +18,5psi at that altitude running 2960rpm.

Originally posted by Knegel

Ok, lets see, the P51B...

I'm not comparing the planes but just looking if the engines lived up to the specifications. The output can be calculated quite accurately from the MAP and the P-51B, HF IX and Gj+FX data can be easily used to check the output of the engines because the altitude and MAP combinations are given in the data. The error caused by RAM is rather small as can be seen by comparing the FTHs of tested Merlins

Originally posted by Knegel

btw, it wasnt me who came up with the V-1650-3 power to discuss the merlin high alt performence.

It was Viking who started to compare FTHs  and I used the test data to point out that it's the reached output which matters. Later you started to compare DB specs vs tested Merlins and so on... Your argument has changed quite a bit since that and not just once.

[Knegel]

Hi,

of course my argumetation have changed, cause i look to the same problem from different sides, while you remain to try to estimate power values out of a few curves, where we dont know exact in what way they got recalculated, without to look to the plane performeneces, which can give a good hint, if the estimated engine performences are possible or not.

Interesting is that when Viking came with FTH´s, you came with the best available Merlin test regarding the FTH. But when i come with the static power, you say your prevoious stated engine is not nearly a Merlin70 and the Merlin70 was much more powerfull, while the plane performences of the P51B and the Spitfire HF´s show that this simply cant be.

And you always claim that the DB´s dont reach their specs, while the speeds of the planes show very good performences, but of course we safely can assume that this speeds can be up to 50km/h to fast, cause the german engeeners like to offer absolut useless comparison sheets.  

Of course this explain how the heavy Bf109K4, G10 and G14AS could be faster than the HF Spit up to 9000m, while the Merlin70 power must have been good above the DB605AS + D´s power.

But maybe also the P51B Speeds are without mach correction and so it didnt fly 440mph@9km, but only 410mph, what actually still would be very fast for a so powerless plane with a 1000kg disadvantage(in comparison to the Merlin70 powered Spitfire).

Of course its easy and usefull for your argumentation to wear blinders and to relay on the available engine datas, while we actually dont have any tested DB605 and Merlin70 power curve.

To mix up the good FTH´s of the tested Spit´s, with the static power stats simply dont fit to the tested flight performences.

My conclusion remain that the  Merlin70 didnt reach the specs regarding the power, while the DB´s didnt reach the specs regarding the FTH, resulting in a rather close match regarding the power in hight.

Greetings,

Knegel