Late Me 109 G & K engine settings

[Kurfürst]

Originally posted by pasoleati
One more thing. It is obvious for anyone with brains why the DB might have had lower coolant temps: poor design.  

And now the switch, ROFLOL. First you try to proove the DB had similiar coolant temps as the Merlin, now that it`s bad becuse it`s aint similiar.
Whatever design feature of the DB = BAD.
Man you are biased.

[pasoleati]

Re Sabre. The fact is that Napier stuck to the original CR throughout Sabre´s development and increased power solely thru increased boost.

And the fact is that all allied major engines had lower CR than 7:1 except for the sleeve valve designs. E.g. the post war Wright R-3350 Turbo Compound had a CR of 6.7:1 even on 115/145 fuel.

Furthermore: when engines are modified for Reno racing (where the power really needs to be maxed out), the mods never call for increased CR. The additional power is allways obtained with major boost increases coupled with minor RPM increase (around 10% rpm increase for radials, Merlins and Allisons tolerate more).

The bottom line is: for a given octane rating available, you can allways have more power by having low CR/high boost than by having high CR/low boost. All that this requires is capable supercharger designer. And this DB obviously hadn´t.

[pasoleati]

Ahh, addendum: I have to inform you that my facts are not based on Finlandia drink for I happen to be a teetotaller. They are just the truth as it is.

[Staga]

Not that easy; with bigger boost you need  more power to the SC and with ordinary supercharger systems that meant the boost had to be controlled (usually) with a butterfly flap after the SC.
That also meant that altitudes under the FTH part of the enginepower was wasted to run the SC in higher RPMs than what was necessary.
WIth higher CR and lower boost you could minimize the power the SC needed but this brought another problems I'm sure you can figure out.

[Kurfürst]

Originally posted by pasoleati
Re Sabre. The fact is that Napier stuck to the original CR throughout Sabre´s development and increased power solely thru increased boost.

The fact that Napier, as well as BMW, Wright etc. went for higher CR, unlike as you claimed and were very successfull with it.

I see a pattern, those who adopted high CR succeeded in developing successfull engines with high powers AND good fuel consumption, those who didn`t, failed.

And the fact is that all allied major engines had lower CR than 7:1 except for the sleeve valve designs. E.g. the post war Wright R-3350 Turbo Compound had a CR of 6.7:1 even on 115/145 fuel.

All Allied engines had caruburrator only which frequently cut out under negative G. I guess that means carburrator is a superior solution than DFI, that why you don`t see any carburators around today! What a silly logic.

Furthermore: when engines are modified for Reno racing (where the power really needs to be maxed out), the mods never call for increased CR. The additional power is allways obtained with major boost increases coupled with minor RPM increase (around 10% rpm increase for radials, Merlins and Allisons tolerate more).

Considering they had to make with Allisons/Merlins only, which were designed this way... another silly example. Increased CR would require a serious design team behind them, not just a few old pros who know how to tickle with the engine a bit.


The bottom line is: for a given octane rating available, you can allways have more power by having low CR/high boost than by having high CR/low boost. All that this requires is capable supercharger designer. And this DB obviously hadn´t.

Splendid claim, too bad it doesn`t resamble reality at all!

But here`s another classic, DB didn`t have a capable supercharger designer.... I laugh myself to death!

I guess DB didn`t design a state of the art hydraulic coupling for it`s engines then. Can you make even more stupider statements, how about just studying JUST a BIT the high performance superchargers DB has come up with. But doh, I guess that they managed to make better performance SINGLE STAGE superchargers than RR managed to create with TWO stages... you have no idea on that, you just keep mentioning some DB feature, blindly stating that everything was bad, but failing to back up your dubious claims with anything.

Just a few DB engines with altitude performance few could match :

DB 628
DB 605 L
DB 603 L, LA, N.

All these had a rated altitude of over 30 000 feet.

[Angus]

Hello again.
Will bypass your technical stuff and plonk in something on a historical basis. BoB era, - after that the engines just went UP in consumption, be it Merlins or DB.
It did indeed turn out to be true that 109's had problems escorting as far as London, which is humbly 97 miles from Calais.
Many a good pilot ditched in the channel because of this.
But what I also found is that it didn't really matter if the 109's were on their own cruise, milling around the bombers, or on slow cruise, winging with the bombers, they still had the problems.
AFAIK, the Germans incorporated drop tanks well before the British. Now was it the 109E-4 or E-7????
The first Spitfires I hear of with drop tanks are Mk V's, and that begins with slipper-tanks. Same with Hurricanes. Those are for ferrying, since they are not droppable.
Common useage of Drop tanks seems to be in 1942 or so.
As far as I can see, Rhubarb missions and even Circus missions were done without them in 1941.
Same goes with the LW raids on London in 1940.
So, about range, it boils down to the same stew. The 109 and Spitfire had short legs, - the Mk I vs the 109E would both be in the 1-2 hours range, heavily depending of the power applied.
Seems though that the 109 raids ceized at the London area, while I have LW claims on Spitfires shot down at St Omer or so, as well as Hurricanes actually. That is actually rather a similar distance, a tad further perhaps.
So, just wondering if this fits. I know one person that will disagree, but it wouldn't be fun without it anyway.

[MiloMorai]

All Allied engines had caruburrator only which frequently cut out under negative G. I guess that means carburrator is a superior solution than DFI, that why you don`t see any carburators around today! What a silly logic.

Still with your ignorance of Allied induction Barbarossa  Isegrim.

Bendix and SU were producing fuel injection syatems.

"In 1942 the petrol injection pump was developed for the aero-engines, first fitted on Mosquito aircraft. Two S.U technical staff had taken out a patent in 1939 but the firm could not get anyone interested in it at that time. After three years of neglect, the S.U design was adopted and the new British petrol injection pump came into general use in the last year of the war. It was later built under licence by an American company and called The Simmonds Injector Pump."

As for the injectors, as in all mechanical fuel injection systems, the warplane’s were spring-loaded, open full-time, and oscillated rapidly to maximize atomization. With parts and controls like these, early fuel injection systems were little more than controlled leaks

Even the Griffon had a RR single point injection unit.

One does not see many carb induction systems around today because of emmision issues. Computerized FI induction reduces emmisions.

[pasoleati]

Will be replying later in detail but Kurfürst, tell me one thing: did Napier increase Sabre´s CR from the Sabre I to Sabre VII? No, they did not.

And would you mind going back a few messages where I clearly pointed out the superiority of increasing boost over increasing CR as a means to increase power? The quote was pretty clear.

And you nicely forget that supercharger design also includes IMPELLER design, and here DB obviously screwed up.

[Angus]

Never heard of a P51 cutting out in Neg-G's Barbi.

Getting desperate?

The Neg-G problem was solved, however at first in the field.
Same actually with the Spit's stability problems.

You should fly AH. They have a wonderful flight engine where you can explore these features

[pasoleati]

Let´s have a reminder of basics here.

1) German engines had direct fuel injection. This means that the individual injector is located in the combustion chamber and the fuel supply is sequential (i.e. not continuous)

2) Some Allied engines had carburettors. British carbs were made either by S.U. (Skinner´s Union) or Claudel-Hobson. These were standard float type carbs susceptible to negative-g cutting. In the US similar carbs were made by Holley.

However, vast majority of US engines and most later war Merlins were equipped by pressure carburettors, or actually single point injectors.

[pasoleati]

These were usually made by Bendix-Stromberg. This system supplied fuel under low pressure and injected it into the eye of the blower impeller. These were not susceptible to negative g-cutting.

Some later war Merlins had a slightly different S.U. system. It had a 5-plunger variable displacement pump injecting fuel like the above system, but it did not need venturi tubes for mixture control. This was further simplified by having a gear type pump instead of the plunger pump in very late engines. The latter system was developed by RR.

Bendix system is often called pressure density and the SU/RR type speed density system.

[pasoleati]

Now, in 1945 US Navy conducted a comparison between a Bendix equipped R-3350 and a direct injection variant (similar to German systems). It was found that performance WAS NOT improved by the direct injection system, but mixture distribution was. As the R-3350 suffered from poor mixture distribution, later models were equipped by the DI system. However, it is most interesting to note, that P&W did not use direct injection in any of the R-2800 models, and only few of the R-4360s had it.

As for the CR, the Sabre retained the same CR of 7:1 from the first to the last models while the boost was increased from +7 in the Sabre I to +20 in the Sabre VII with power increasing from 2000 hp to 3500 hp.

P&W´s R-2800 B-series, CR 6.65:1 in all models but boost increased from 52 inHg to 64 inHg and power increasing some 30%.

C-series had a CR of 6.75:1 and again, all power increases were obtained by increasing boost. It should be remembered that the C-series was basically a new engine, with cylinder dimensions remaining the common denominator to the B-series.

Bristol Centaurus. CR 7.2:1 in all models and all power increases by increased boost.

And the list goes on. In short, NO OTHER MAJOR MANUFACTURER INCREASED CR TO GET MORE POWER OUT OF A PARTICULAR DESIGN.  THEY ALLWAYS INCREASED BOOST.

These are facts.

[eddiek]

"Monster turbocharger? Been watching too many horror movies?

How much Finlandia do you drink before posting? Should I say, P-47, a six ton monster? Should I point to a NACA report on supercharger technology, that points out that installing a similiar effiency turbocharger means 500 lbs extra weigth, whereas a DVL hydraulic cluthc comes with... 50 lbs extra?"

Umm.....excuse me, but the P-47 did not use an Allison engine, which you stated used a "monstre turbocharger" and still struggled to exceed 1600hp.  It used a radial engine, and was producing 2000+hp from the early models to 2800 in the later ones.
If you're gonna name a particular plane as an example to try and back up your debate, you might want to get the planes correct.

[Kurfürst]

Let´s have a reminder of basics here.

1) German engines had direct fuel injection. This means that the individual injector is located in the combustion chamber and the fuel supply is sequential (i.e. not continuous)

I guess this is fairly obvious to even Mr. MM, he only puts the nonsense because
a, it`s nice to lead astray those who don`t get what the diffo between 'fuel injection' and 'direct fuel injection' is.
b, He only wants to flame.

Then again, I have to point out the facts which you choose to ignore.

As for the CR, the Sabre retained the same CR of 7:1 from the first to the last models while the boost was increased from +7 in the Sabre I to +20 in the Sabre VII with power increasing from 2000 hp to 3500 hp.

Yep, and notice the Sabre uses high CR 7 : 7 just like the early  DB 601 does.
Notice the Bristol Centaurus uses high CR 7.2:1 almost exactly what the DB 605A does (7.3 : 1)
Notice the BMW 801 uses CR 7.22 : 1 almost exactly what the DB 605A does (7.3 : 1).


You keep telling us that for some mysterious reason, high CR is a bad thing, yet we see again and again some of the best WW2 aero engines use very much the same CR, and following the same path as DB choosed, EXCEPT the R-R.

The common perception is sadly however that those engines which utitlize high CR can develop as much or more power with less complications, and MASSIVELY better fuel effiency, than those which only rely on increasing boost.



In short, NO OTHER MAJOR MANUFACTURER INCREASED CR TO GET MORE POWER OUT OF A PARTICULAR DESIGN. THEY ALLWAYS INCREASED BOOST.


It`s funny that you mention facts, and then ignore them.




Wright also progressively increased the CR, ie. earlier to later Wright engines :

Whirlwind : 6,1 : 1
Cyclone 9R : 6.4 : 1
Cyclone 9R R-1820 : 6.7 : 1
Cyclone 14 GR 2600 : 6.9 : 1

So did DB.


THEY ALLWAYS INCREASED BOOST.

So if the other guys went stupid, and ignored direct fuel injection, DB should drop it too? Ridiculus.
If the other guys went stupid, and ignored hydraulically driven superchargers, DB should drop it too? Ridiculus.
If the other guys went stupid, and ignored the advantages of inverted vee construction, DB should drop it too? Ridiculus.
And similiarlytIf the other guys went stupid, and ignored the advantages of inverted vee construction, DB should drop it too? Ridiculus.
So if R-R alone went stupid, and ignored CR, DB should drop it too? Ridiculus.

Is that the logic you follow? The only way of increasing power is increasing boost? Power output is a factor of both MAP and CR, given the two determine the final pre-detonation pressure in the chamber, doh. You got somewhere that notion that increasing CR is bad... yet we see high CR was a watermark of those engines which were EFFICIENT, not just worked-up fuel hogs. We see that all the 2000 HP class engines, ie. Sabre, BMW 801, DB60x series all had high CR.

Who was the only pigheaded company to use low CRand got fixated on MAP only ? That`s right, R-R.


You also ignore the fact that DB increased boost progressively through the war :

DB 601A : 1.3 ata
DB 601Aa : 1.35 ata
DB 601N : 1.35ata
DB 601E : 1.42ata
DB 605D : 1.5ata
DB 605AM : 1.7ata
DB 605 DM : 1.75ata
DB 605 DB : 1.8ata
DB 605 DC : 1.98ata (was under development for 2.3ata)


You keep that fact ignoring. The other fact that during this, DBs went with 52% increase in MAP from 990 to 2000 PS, 100+% improvement in power output, AND managed to get acceptable fuel consumption for it. You fail to grasp that DB was increasing BOTH the Compression Ratio, and Manifold Pressure.Now THESE are the facts, and that the low CR Merlin 66 needs 197 gallons per hour to produce 2000 HP, whereas the high CR DaimlerBenz engines can do the SAME on 30% less, 143 gallons per hour. Try to get a grip on that FACT.

Also let`s note DB could successfully boost the DB 601 to 2700 PS in 1939, RR failed to achieve the same until postwar. High CR bad, huh?


And would you mind going back a few messages where I clearly pointed out the superiority of increasing boost over increasing CR as a means to increase power?

What, you mean that utterly stupid example between supercharged and non-supercharged engines... yes you proved... that supercharged engines are more powerful. Who`d have guessed. But come closer, I tell you a secret.... All Daimler Benz engines were supercharged - just like any other engine. That`s right. No joke.

You also had some dubious comments about DB being unable to design good superchargers.

Now please, tell me, which engine could produce up to 1945, under 1000 kg weight

1350 HP at 9600 meter ?
1760 HP at 9000 meter ?
1950 HP at 11 000 meter ?
1200 HP at 11 000 meter ?

I am speaking of the DB 605 L, 603 LA, 603N, 628 here.
Come on, it can`t be that hard to beat those 'crappy' DB superchargers....

[Kurfürst]

Originally posted by eddiek

Umm.....excuse me, but the P-47 did not use an Allison engine, which you stated used a "monstre turbocharger" and still struggled to exceed 1600hp. If you're gonna name a particular plane as an example to try and back up your debate, you might want to get the planes correct.

[/B]

P-47 didn`t use the Allison with a monstre turbocharger.
The P-38 did. I didn`t linked the Allison and the P-47 together anywhere, you did.