Inverted V engine vs. V engine

[Siegfried]

The Luftwaffe page , Daimler-Benz DB 605

Kurfurst - Your resource on Messerschmitt Bf 109 performance



DB 601 A-0 Dry weight: 590kg Weight with devices: 705kg
DB 601 A-1 Dry weight: 610kg Weight with devices: 715kg
DB 601 Aa Dry weight: 590kg Weight with devices: 705kg
DB 601 N Dry weight: 610kg Weight with devices: 780kg
DB 601 E Dry weight: 610kg Weight with devices: 780kg

DB 605 A Dry weight: 720kg Weight with devices: 764kg

DB 605 AM Dry weight: 730kg Weight with devices: 796kg
DB 605 AS Dry weight: 730kg Weight with devices: 796kg
DB 605 ASM Dry weight: 730kg Weight with devices: 796kg

DB 605 DB Dry weight: 745kg Weight with devices: 815kg
DB 605 DC Dry weight: 745kg Weight with devices: 815kg

I don't know which devices were intentioned with "Weight with devices"!
To my opinion it is a power egg without cooling


Because a Jumo 213 with supercharger all devices and cooling was 1,8 ts.

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The above claim, which seems a little high to me, would surely be for the intercooled two stage 3 speed Jumo 213E and be inclusive of radiator, all fluids, accessories, oil cooler (integrated), starter, alternator etc. The non inter-cooled single stage Jumo 213E would be lighter.

The Merlin 60 series, those with two stage superchargers, came in at 744kg dry so the DB605AS, DC (those with over sized superchargers)
had about the same weight and indeed power as the Merlin. It's very important to note that the German engines generated equivalent power on much
lower rated octane fuels, something that was necessary due to the cost of synthesizing this kind of fuel and the danger of supply interruption.

The Daimler Benz engine had a relatively high compression ratio compared to the Merlin, Alison and Jumo 213. High compression ratios improves efficiency
and power to weight ratios. It also means that the supercharger is there primarily as a device to compensate for altitude rather than to
overboost the engine for extra power, as it was in the Merlin and hence the DB engines were not quite so much in need of a two stage inter cooled super charger.

There was to be a DB605L for the Me 109K14, with a two stage supercharger, but without an inter cooler. It's weight was not significantly higher.

The Jumo 213 was a Grifon sized engine with similar compression ratio. In the E and F versions it did use a two stage supercharger and inter-cooler (I believe smaller in the F) but again note that on the Ta 152H Jumo 213E that its power was achieved with B4 (87 octane fuel)

Comparing Allied versus German engines is somewhat confused by the generally superior fuels the allies could afford, by the time the production of C3 fuel was increasing the allied oil bombing campaign seems to have forced the Germans to engineer their engines to accommodate greater fuel flexibility rather than optimising for C3. For high altitude work the British made a minor technical advance with the two stage inter cooled Merlin while the turbo superchargers favored by the Americans required refractory metals the Germans could not afford to use.

 

[Siegfried]

LOL!

And an boxer is not designed to run on the west and the east/ or on the left and right side?
To my opinion this statement is absurd, because a Jumo 213 could manage 3250 rpm as normal piston speed. I don't see any oil control problems!
Or could you tell me why on earth a late DB 605 could manage 1.8 ata and the Jumo 213 E was equal/could match with any RR Merlin or Griffon ever produce in the same timeline?

The Jumo 213J was to run at 3750 RPM and produce around 2750 ps but never left the bench.

Aviation engines have a dry sump, especially ones expected to do aerobatics and air combat maneuvers., so inverting the engine doesn't add too many difficulties.

The advantage of the inverted installation are simple to understand: it gives a clean installation, better forward visibility, keeps the exhaust stream away from the cockpit, it puts the thrust line at a level that trim changes with throttle changes are more neutral and allows the technicians access to the rocker covers and spark plugs while on the ground and allows the engine to be suspended from beams rather than cradled within a tube structure.

 

[Siegfried]

Short lifespan was not uncommon for piston engine in 1944! By then, power was very great - so was strain. 40 hours - similiar for Soviet VK 107, or German DB 605D. Or consider Jumo 004B.

May not as disadvantage as seems. Consider combat sortie - 1 hour. This means plane will fly 30-40 combat sortie before engine needs replace.. but will plane be not even hit once this time? Or shot down? For wartime, it is ok. For peace - not OK.

My understanding is that the mature DB605A was rated to 220 hours before being sent back to a factory or workshop for a rebuild, with the engines potentially undergoing several such trips. There was an field level overhaul at 100 hours and below that spark plug and oil changes etc. Consider a 100 hour life; that is about 100 Me 109 missions. The chances of battle damage or over use of war emergency boost damaging or expiring the engine before then must be extremely high. Why would one bother chrome plating the cylinder liners for instance if the engine is going to be battle damaged or even shot down before then.

Consideration should be given as to how engines are serviced; if they are sent back to the factory for a rebuild that does not mean the engine of the engines life. It just means has been decided to do its maintenance in the factory rather than the field.

 

[Shortround6]

Many allied engines were overhauled at regional depots or overhaul centers. It being rather impractical to ship engines from Egypt or the Solomon Islands back to factories in England or the US. Using factory rebuilds with a short time between overhauls ( a system the Russians used extensively with Jet engines in the 50s and 60s if not beyond) means that you need a higher percentage of engines to account for the ones in transit and under going overhaul. Some Western engines were built at a rate of 50% more engines than needed to equip air frames plus a quota of spare parts. Many allied piston engines were rebuilt a number of times. Engine life was also a "suggested" point at which an engine should be pulled for overhaul, regardless of how well it was running at the time, it was by no means a guarantee that the engine would last that long. In some cases only 30% of engines made it to their suggested "life" and in some theaters (North Africa for one) it would be considered a miracle if an engine lasted that long.

 

[Milosh]

Info on DB505 engines, http://mitglied.multimania.de/luftwaffe1/aircraft/lw/DB605_varianten.pdf

 

[Tartle]

Shortround6... you make some pertinent points... when the Napier Sabre powered Typhoon went into general service squadrons had nearly twice as many aircraft in order to overcome unserviceability issues. Even in 1944/5 Napier were making at least 50% more Sabres than required for new installations in order to keep the RAF flying. Even clapped out Merlins were less of a burden in manhours. When we had a Merlin running session in 2009 I got to talk with service engineers/technicians who kept Spits flying in Egypt.. they said they used all the tricks in the book to keep them in the air, rather like I remember doing in the 60's on clapped out BSAs and Norton motor cycles... boring out cylinders, bigger pistons, plating, etc,etc. but they said as the Merlin was basically a good engine they could do those things and still fly the Spits.