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Author Topic: WEP on the C205  (Read 3758 times)

Offline MiloMorai

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WEP on the C205
« Reply #30 on: May 26, 2004, 05:55:42 AM »
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Ever wondered why Mike`s references suddenly end in the spring of 1943 ?

Just maybe, he has not got around to doing comparisons to the later Messicraps.:)

The G-5 is a bad performer??? You might be right, for with JGr25, it could not catch DH Mosquitos. It came off the assembly line from May '43 to Aug. '44. Seems Mike was comparing earlier Spits to a 1944 109.:)

When it comes to info on the 109, I would believe what Butch has to say over Issy, with his agenda, any day.


A Merlin with 15lb boost was operating at 2.02 at(29.7/14.7). With 18lb boost, it would be 2.22at(32.7/14.7). With 25lb boost, it would be 2.70at(39.7/14.7) Seems the DB engines were just a wee bit on the weak side with only a max of 5.5lb of boost.
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Offline butch2k

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WEP on the C205
« Reply #31 on: May 26, 2004, 06:51:17 AM »
After giving it a more thorough check it appears that the 1.42ata boost was cleared in November 43, a revised DB605A manual (not motorenkarte) being re-issued at that time. Note that the motorenkarte was not updated until April 44 for some unknown reason.
IIRC (i'm at work) the time limit at 1.42ata had been reduced to 1 minute (1944) compared to the 3 originaly planned (1942).
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Offline VO101_Isegrim

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WEP on the C205
« Reply #32 on: May 26, 2004, 07:32:46 AM »
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Originally posted by MiloMorai

A Merlin with 15lb boost was operating at 2.02 at(29.7/14.7). With 18lb boost, it would be 2.22at(32.7/14.7). With 25lb boost, it would be 2.70at(39.7/14.7) Seems the DB engines were just a wee bit on the weak side with only a max of 5.5lb of boost.


Interesting Milo.

It appears that, as per your data, the DB 605 developed 2000 PS at 1.98ata, whereas the Merlin at 2.02 ata (+15lbs) could develop 1340 HP.

Speaking about effiency.. :D
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Offline butch2k

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WEP on the C205
« Reply #33 on: May 26, 2004, 07:41:10 AM »
I have never understood why one would compare Allied vs German engines just on the boost pressure...
It would be better to compare boost x Compression ratio... since the German relied on low boost but high CR and the Allied rather the contrary.
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Offline MiloMorai

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« Reply #34 on: May 26, 2004, 09:36:15 AM »
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Originally posted by VO101_Isegrim
Interesting Milo.

It appears that, as per your data, the DB 605 developed 2000 PS at 1.98ata, whereas the Merlin at 2.02 ata (+15lbs) could develop 1340 HP.

Speaking about effiency.. :D


Interesting indeed Issy, now what was the hp without using 'boost juice', for that is the only way they could reach that high of a hp number and boost number? Note the selective hp number stated by Issy, for the Merlin at 15lb produced ~1550hp+. Typical of him.

As can been seen in this graph, the Merlin could produce 2000hp plus, as well'.:)


The Griffon 65, an engine of simular displacement to the 605, produced over 2000hp without using  'boost juice'. With ADI, the power was even higher, ~2350hp+.

The Griffon 58 delivered 2455hp at low level with ADI ('boost juice') and 25lb boost.
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Offline VO101_Isegrim

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WEP on the C205
« Reply #35 on: May 26, 2004, 11:36:43 AM »
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Originally posted by butch2k
I have never understood why one would compare Allied vs German engines just on the boost pressure...
It would be better to compare boost x Compression ratio... since the German relied on low boost but high CR and the Allied rather the contrary.


Neither I had understood such comparison in a complex matter, I just gave him some typing work and to let him waste an hour on searching the web - the world is free from him during that. ;)

To me it appears that the development at DB was a lot more systematical though, ie. swept volume, supercharger size, compression ratio, boost pressure were all increased, fuel injection, hydraulic coupling was introduced.. The main path of development seems to be more concerned about improving the engine`s overall effiency, rather than just focusing on increasing power output via MAP, as R-R did, employing an advanced supercharger technology that was perhaps not the best solution to be built into a fighter (ie. w. intercooler and it`s associated extra items).

R-Rs development reminds me of a small team of of engine tuning experts, while DB`s was more like an organised group of engineers with rather clear ideas how to develop a basic design through the years. And the difference is very clear between the approach of the two by 1945, rather identical power outputs overall, but DBs do it with less fuel, less weight, less bulk without sudden power drop characteristics of the R-R designs. Equally effective, but far more efficient.
« Last Edit: May 26, 2004, 12:09:07 PM by VO101_Isegrim »
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Offline MiloMorai

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WEP on the C205
« Reply #36 on: May 26, 2004, 01:17:16 PM »
Typical Issy.

Actually Issy, while the 'pute was doing its number crunching, I had some free time.:) Did not catch many ambulances lately it seems since you post all day long.  

FYI, Issy R-R was using fuel injection during WW2. When you start comparing weights add in the weight associated with the 'boost juice' > no big hp numbers without the 'juice'.:)

R-R knew what ADI could do and had the choice to use 'boost juice' but decided against because the extra complexity and weight were not worth the additional power. Much more logical than the complexity the Germans liked to add. Even BMWs method of injecting extra fuel was better.

Interesting that the Germans salvaged the sc gears on the Merlins because they were better than what they could make.

Oh yes the DB engineers were much more organized. One only has to look at all the dead-end/no-go engines they tried to develope from the basic engines.
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Offline GScholz

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WEP on the C205
« Reply #37 on: May 26, 2004, 02:21:49 PM »
Oh my God, another Spit vs. 109 hijack. Will you guys (you know who you are) give it a rest! Argue by email if you have to argue.
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Offline leitwolf

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WEP on the C205
« Reply #38 on: May 26, 2004, 03:09:12 PM »
My engine is bigger than your engine ;)
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Offline GScholz

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WEP on the C205
« Reply #39 on: May 26, 2004, 03:14:10 PM »
More like RR and DB tattooed dick-waving in public.
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Offline MiloMorai

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WEP on the C205
« Reply #40 on: May 27, 2004, 09:26:39 AM »
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Originally posted by GScholz
More like RR and DB tattooed dick-waving in public.



You sort of got it, for is more like pointing out, Issy's is not a big as he wishes it was. :)
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Offline joeblogs

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comparing engines
« Reply #41 on: May 27, 2004, 12:15:33 PM »
A better measure is Brake Mean Effective Pressure (BMEP), but even here you have to take into account differences in maximum RPM across engines.

At the end of the day, you want to know for the all-up weight of the engine, supercharger, boost system, oil, etc, the mass of air the engine pumps out per unit of time. Even this is a measure of gross power. You want to deduct the energy required to drive the supercharger, etc.

-Blogs

Quote
Originally posted by butch2k
I have never understood why one would compare Allied vs German engines just on the boost pressure...
It would be better to compare boost x Compression ratio... since the German relied on low boost but high CR and the Allied rather the contrary.
« Last Edit: May 27, 2004, 12:48:24 PM by joeblogs »
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Offline Angus

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WEP on the C205
« Reply #42 on: June 01, 2004, 09:16:11 AM »
Well, at least the thread produced some engine data ;)
And as usual, Milo and Issy start their scruffling.

"It appears that, as per your data, the DB 605 developed 2000 PS at 1.98ata, whereas the Merlin at 2.02 ata (+15lbs) could develop 1340 HP. "
Bear in mind that the Merlin is what, 24 litres, and the DB is what, 32 litres?
It's apples and oranges really, the base design of those two are not quite exactly the same. Different approach to squeeze the power out.
The Merlin produces more power/torque for the same weight, using high grade fuel instead of MW or whatever.
The DB produces amazingly good power out of lower boost and lower grade fuel, however applying MW, which is very very bad for an engine actually.......
The Merlin could actually be squeezed up to well over 2000 hp using special juices, but it was not really worth it. Imagine the power there pro volume though. They actually fiddled with that in 1939!
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Offline GScholz

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WEP on the C205
« Reply #43 on: June 01, 2004, 12:04:32 PM »
Why is using MW50 bad for the engine? Some allied late war planes used water injection. In AH the F4U4 for instance. The Merlin does not produce more power/torque for the same weight, the two engines weigh almost exactly the same.
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Offline joeblogs

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comparing engines in many dimensions
« Reply #44 on: June 01, 2004, 04:41:44 PM »
A lot of this is covered in the charts posted at

http://www.hitechcreations.com/forums/showthread.php?s=&threadid=106773


-Blogs


Quote
Originally posted by Angus
Well, at least the thread produced some engine data ;)
And as usual, Milo and Issy start their scruffling.

"It appears that, as per your data, the DB 605 developed 2000 PS at 1.98ata, whereas the Merlin at 2.02 ata (+15lbs) could develop 1340 HP. "
Bear in mind that the Merlin is what, 24 litres, and the DB is what, 32 litres?
It's apples and oranges really, the base design of those two are not quite exactly the same. Different approach to squeeze the power out.
The Merlin produces more power/torque for the same weight, using high grade fuel instead of MW or whatever.
The DB produces amazingly good power out of lower boost and lower grade fuel, however applying MW, which is very very bad for an engine actually.......
The Merlin could actually be squeezed up to well over 2000 hp using special juices, but it was not really worth it. Imagine the power there pro volume though. They actually fiddled with that in 1939!
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