The Secret Horsepower Race by Calum Douglas (and piston engine discussion)

In Dan Sharp and Calum Douglas' great Me 309 book, a Major Petersen mentions that the Jumo 213 was smaller than the DB 603 when both engines weighed virtually the same. Further is said that the 213 requires a smaller radiator than the 603.

Looking at the Fw 190D and Ta 152, the early Doras' radiator wasn't sufficient so the DB 603-powered D-14/15 obtained
the Kühlerkopf of the Ta 152C.
Apart from the oil cooler the drum rads of the Ta 152 subtypes C and H look the same. The absence of an oil cooler means more of the radiator matrix could be used for cooling of Jumo 213E/F which is said to need less cooling than the DB 603 anyway?

My conclusion is that the Jumo 213 simply got more cooling although it needed less than its counterpart.
Combined with the higher exhaust thrust it provided greater propulsion.

Anyone enlighten me on this one?
 
Having just one exhaust valve reduces the heat flow in the exhaust port conciderable. During the 90th, Mercedes used three valve heads for their V engines (cars) and truck engines, mainly because the 3V configuration enabled higher exhaust temperatures and faster light off for the cat. In case of the Jumo, this also totally explaines the higher exhaust trust

Note, that most of the heat flow into the cooling system ist not comming from the cylinders but from the exhaust ports and the valve seats.
 
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Nicknick said:
Having just one exhaust valve reduces the heat flow in the exhaust port conciderable. During the 90th, Mercedes used three valve heads for their V engines (cars) and truck engines, mainly because the 3V configuration enabled higher exhaust temperatures and faster light off for the cat. In case of the Jumo, this also totally explaines the higher exhaust trust

Note, that most of the heat flow into the cooling system ist not comming from the cylinders but from the exhaust ports and the valve seats.
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Any source for that claim?
 
Ok, I have it ob my PC at home, you get it tomorrow despite youre question could have been more polite....
 
Nicknick said:
Actually, I was searching a nice graphic vom Curtiss-Wright but couldn't find it... This here will do the job too (https://core.ac.uk/download/pdf/289945175.pdf ):
Click to expand...
By that, 49.4% of all heat loss comes out of the cylinder heads as a complete unit. Cylinder is taking more thermal load than I expected, guess I need to add oil squirters to cool the underside of the piston.
 
It is about 68 %, don't forgett the valves. The terminus "head" is misleading, he surly ment the flame deck with that.
 
Nicknick said:
It is about 68 %, don't forgett the valves. The terminus "head" is misleading, he surly ment the flame deck with that.
Click to expand...
Head = combustion chamber
Port = Exhaust Port (intake port is not particularly hot)
Valves = Exhaust valve(s), (intake valves are not particularly hot)
Liner = cylinder bore
Piston = crown of piston exposed to combustion temps
 
The 213 does not have a fluid drive supercharger coupling, which can transfer a vast amount of heat to oil at altitudes below rated, in addition its generally better designed with higher coolant pressure and generally higher coolant temps than contemporary German engines which obviously lowers heat to fluid. The 3 / 4 valve discussion is hard to evaluate, as the valve is of course a lot larger and then in the port itself of course opens out into a fairly familiar cross section. I would strongly suspect that the lack of a fluid SC drive, high pressure coolant system and integrated oil/water HX are the primary drivers here. The 3 valve head was probably valid in 1935 when rpm`s were capped by mechanical limits but it really wasnt a great idea long term, its a shame for jumo that the didnt fix that until the "J", which was a dramatically technically superior engine to anything the Allies had, just far too late.
 
Each head has a different geometry, so there is no exact percentage of heat losses for the mentioned components.

I'm not saying, three valve heads are superior, but they tend to have lower heat losses, which is confirmed by several puplications from MB (I can't quote them, but I read them...). It is also quite obvious, that a singe big pipe has less surface that two smaller pipes with the same cross section.

In modern designs, the four valve pent rouf heads enable a central spark plug whereas the three valve heads often have two plugs out of the center. Unlike in modern designs, (As said before) the plug position in the Jumo 213 is superior to the four valve aero engines of its days, because the parallel four valve heads had their plugs on the perimeter of the combustion chamber.

Despite that, one singe exhaust valve is harder to cool and the gas exchange work ist surly lower for the four valve configuration.
 
Were the Germans ever able to catch up with the higher efficiency of Allied radiator?
Those of the Spitfire were of only 55 % the size of German rads on the Me 109F/G.
 
I think it had more to do with the cooling temperature. The bad casting quality prevented the Germans from using higher cooling pressures if I remeber it right. I believe Behr builded the first modern aluminum cooler during WW2, so the cooler itself wasn't the problem.
 
Nicknick said:
I think it had more to do with the cooling temperature. The bad casting quality prevented the Germans from using higher cooling pressures if I remeber it right. I believe Behr builded the first modern aluminum cooler during WW2, so the cooler itself wasn't the problem.
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And the casting quality wouldn't improve until the end? Was that a question of inferior materials, too?
 
You will find that the cooler itself WAS a catastrophic part of the problem...

The tubes were squashed flat from round, and deeply unsurprisingly when you put pressure inside they turn back into tubes again.

109 rads expand like bicycle tyres when you try running high pressure>

View: https://youtu.be/ImEpk1s-Vk0?si=-lxleQhH_rGQh8-g&t=2975
 
Something about the German cooler development during the war, here the same design (to the very right side and at the bottom) is praised for beeing more effective and pressure resistant...

(Kyrill von Gersdorf et al: Flugmotoren und Strahltriebwerke)
 

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Nicknick said:
Something about the German cooler development during the war, here the same design (to the very right side and at the bottom) is praised for beeing more effective and pressure resistant...

(Kyrill von Gersdorf et al: Flugmotoren und Strahltriebwerke)
Click to expand...
I`m sure thats what the sales brochure said, but its more or less impossible to imagine a less suitable design for resisting internal
pressure, a very significant part of that is that not only is there nothing stopping the inside faces of the flattened "O" from moving apart internally, the tubes are not even brazed together externally. The whole lot is a floppy mess. Unsurprisingly, the idea for making tubes this way appears to have utterly vanished, never to be seen again.

Its a hopeless idea for making pressure resistant matrixes, and I suspect was only ever used because copper was in such sort supply that some sort of very quick and easy method was needed in a hurry in the late 30`s to make aluminium coolers.

Me109G_Radiator_DB605_006.jpg
 
It definately looks better as a drawing....
These type of cooler was developed around 1930 (according to my sorce above), at a time when copper wasn't really rare in Germany. I guess it was lighter an cheaper back than and the shortage of copper and brazzing materials made it an obvious choise later in the war. I guess,, pressurized cooling systems apeared later than this cooler design, so it became outdated during the war but couldn't be replaced with something better...
 
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Nicknick said:
It definately looks better as a drawing....
These type of cooler was developed around 1930 (according to my sorce above), at a time when copper wasn't really rare in Germany. I guess it was lighter an cheaper back than and the shortage of copper and brazzing materials made it an obvious choise later in the war. I guess,, pressurized cooling systems apeared later than this cooler design, so it became outdated during the war but couldn't be replaced with something better...
Click to expand...
Just remember that the specifications for future military aero engines (called "large" aero engines) at the time, were laid down in 1928, which included a stipulation that high pressure high temperature cooling ought to be developed (why this didnt happen is still not entirely clear, (I suspect they just ran out of time to develop ALL the features stipulated). Whilst with the existing trade arrangements Copper may have been "available" in 1930, the fact there was very little (if any) actual ore in Germany, would have been well known, as would the fact that once hostilities started, such "externally" available materials would be likely to vanish would also have been appreciated, preparations along these lines are clear from the synthetic fuel programme, which was being built at this approximate time. So I would not underestimate the degree of forward planning even a decade before the war in Germany.
 

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