Terminology and engine data

[tomo pauk]

The chart that covers Shvetsov 14-cylinder radial engines; M-88B is Tumansky's development of Gnome Rhone 14 cyl radial. M-63 is Shvetsov's 'variant' of Wright R-1820.
BMW-801A is also there, for comparison.

Link to the accompanying table, same source as graph (can be translated): Íîâàÿ ñòðàíèöà 1. The table's source puts the ASh-82 and 82F as being equal in power?

 

[GregP]

Thanks, Tomo!

Obviously the horizontal axis is height in km. Not so obvious is the vertical axis. It is clearly power I think, but is it cv, HP, or what? The cyrillic letters don't mean much to me ... I think it is "ps," right?

After a slight rotation and adding some intermediate minor gridlines, this is what I get.

Again, thanks!

 

[tomo pauk]

Yes, vertical axis is for HP (actually, CV?). Note that vertical line to the left denotes take off power.

 

[Denniss]

Soviets used metric HP (PS, CV), not the imperial hp.

 

[GregP]

I screwed the chart up above. Without noticing I broke up the intervals into six minor gridlines instead of the intended five. The corrected chart is shown below so the numbers should be easier to interpolate.

I just washed my fingers and can't count with them yet. Did it again! Wrong chart! Correct one below! Damn!

 

[tomo pauk]

Jumo 210B/C and D/E:

 

[Denniss]

Interesting graph, shows most publications quote wrong power ratings for these engines, 210 B/C having 600PS take-off power instead of the often quoted 640PS (which is max power at ~2.8 km). D/E having 680 Ps for take-off with ~690 PS max power at ~800m, other sources vary wildly from 640 to 720 PS.
Have you graphs for 210A or G?

 

[tomo pauk]

Unfortunately, I don't gave graphs for these.
The person at another site posted a couple of graphs of another few Jumo engines, that I suspect are taken from the book about Junkers engines by Reinhard Müller.
Eg. this is for the Jumo 222, from same site; the E and F being two stage versions. The A/B lines should be for the 'baureihe 3' ('3rd series batch') engines, not the 1st examples.

 

[ohogain]

On a chart referring to a SNCM (Lorraine) 130 Taurus is the following description: Avec réducteur et compresseur à grand diffuseur. Obviously, the engine is equipped with both reduction gearing and a supercharger, but what does "à grand diffuseur" mean? Is it turbocharged?

 

[ohogain]

Dry weight is the only weight that seems to be displayed for aircraft engines. Dows anyone know where one could find operating weights?

 

[Shortround6]

The "operating" weight changes from airplane to airplane for the same engine. For instance ALL engines used oil so a long range plane needs bigger oil tank/s than a short ranged plane. They were ALL dry sump engines. Oil went through the engine, then through the oil cooler and then back to the tank and then to the engine again. Some planes might require bigger oil coolers than others, bomber doing a 20-30 minute climb at low speed but high power may need a bigger oil cooler than a fighter that climbs faster (less time climbing and with more airflow though the oil cooler due to higher speed).
The "dry" weight only includes certain accessories. Electrical generators and hydraulic pumps were often not included. Different sized generators could be fitted depending on the expected electrical load. Since the vast majority of aircraft engines used magnetos for ignition, batteries and generators weren't needed to keep the engine running. However electric propellers, flaps, landing gear and even cooling flaps might make having batteries and generators a real good idea

Same with hydraulics. the pump you need for a small fighter is not the pump you need for a big fighter let alone the pump needed for a multi-engine plane. And many twins did NOT duplicate accessories (pumps and generators) for both engines and LOTS of 4 engined planes only carried 2 sets of "accessories".

P-39s were "all electric", at least the early ones. NO hydraulics and an electric propeller. Some P-40s tried to save weight by taking out the electric starter and battery (or fitting much smaller battery) as they used hydraulic systems for landing gear and flaps and such. operating weight of each engine even if the basic engine was the same ? OK different gear box and drive shaft on the P-39 but you get the idea.

Gun synchronizers varied from plane to plane depending on gun installation as did prop controls, most used hydraulic propellers but some used electric and the pitch control mechanisms varied in weight. Please note the hydraulic propellers were NEVER connected to the the plane hydraulic system but used either engine oil or a separate oil supply and pump.

Some engines were even offered with several different starter options. Hand starters, electric starters, cartridge starters and combination starters (usually hand/electric). The "hand" and electric starters usually wound up a flywheel which, when wound up to speed, was clutched into the engine to turn it over.

Dry weight also doesn't include the exhaust system (usually) but may include the flanges and nuts the pipes are welded to or fastened with.

Liquid cooled engines may vary from one installation for the same engine to another in radiator and coolant weight. And of course fuel systems can vary in weight even with no fuel.

Aircraft designer knew what he needed for accessories and the likely weight of the accessories (or could look them up) for the plane he was designing. If he needed a 1500 watt generator (roughly 60 amp at 24 volts) then he needed that regardless of the what engine he chose and would figure the weight accordingly. Another designer working on a different plane might only need a 900 watt generator (40 amp ?) and lower the weight accordingly.

Throw in different engine mounts and cowlings and the "operating" weight of the same engine in different aircraft can vary quite a bit.

 

[GregP]

Hi,

Don't remember if I have done this before, but here is an Excel file I wrote to convert among the various boost units commonly used in WWII. It is in *.xlsx format and, if you have an earlier version, I can save it in *.xks format if needed.

If you have it already, just ignore this post.

Like everyone esle, I got sick of trying to convert this stuff all the time and decided to do it only once more in this file.

- Greg

 

[IndianaJones]

DB 603 L (with MW 50) and DB 603 N:

From the report "Comparison of the internal combustion engine with the turbo-jet engine, 22 July 1946"


Another one; unfortunately, the source is unknown to me:

 

[tomo pauk]

DB 603 L (with MW 50) and DB 603 N:

From the report "Comparison of the internal combustion engine with the turbo-jet engine, 22 July 1946"

Another one; unfortunately, the source is unknown to me:

Very interesting, especially the 1st picture. Is the source available on-line?
The graph appears in the book 'Flugmotoren Und Strahltriebwerke' by Von Ghersdorff et al.

 

[IndianaJones]

Very interesting, especially the 1st picture. Is the source available on-line?

Not anymore, unfortunately. It was sold by warbid-manuals on ebay, and some preview thumbnails were available.

The graph appears in the book 'Flugmotoren Und Strahltriebwerke' by Von Ghersdorff et al.

Thanks a lot!

 

[Simon Thomas]

...

The Merlin normal power output (International rating. Is there an exact definition about international rating?

...

I found this when poking around the Flight Archive:

As defined in the Air Ministry Airworthiness Handbook for Civil Aircraft (A.P. 1208), international rated power is the brake horse power developed in a test when the engine is running at " international r.p.m." under the standard atmospheric conditions of the rated altitude.

"International r.p.m." is the maximum crankshaft speed at which the engine may be run for long periods, as declared by the maker.

Rated altitude is the lowest altitude at which full-throttle running is permissible or, for supercharged engines, the highest altitude at which the rated boost pressure can be maintained when running at "international r.p.m."

Maximum level flight r.p.m. is the maximum safe crankshaft speed at which the engine may run for short periods (for example, 5 minutes) as declared by the maker.

All tests are to be made at 90 per cent, of the international power and at international r.p.m. All engines must, however, be opened out to full throttle at international r.p.m. for the last 5 minutes of all test runs.

All engines subsequent to the one which is type-tested must develop not less than 95 per cent, of the international power.​

Source: 1940 | 3569 | Flight Archive

 

[IndianaJones]

My humble attempt at visualizing the predicted and actual engine performance in comparison:

While the US performance figure of the DB 603 L with MW 50 fit the graph up to 8 km altitude nicely, it differs considerably at higher alt. The data listed for the DB 603 N does not correspond with the graph at all, it appears that the higher figure are given for the "Sondernotleistung", and the lower for "Steig u. Kampfleistung" if I'm not mistaken; otherwise, I cannot explain that discrepancy.

 

[tomo pauk]

IIRC any kind of piston engine will make zero BHP at 55000-60000 ft (around 16 to 18km) - engine will not produce enough power to overcome internal losses due to having too little oxygen. Thus the US data seems overly optimistic.
'Sondernotleistung' ('special emergency power', equivalent of the US term 'WER wet') works with water-alcohol injection, ie.to be used under the rated height.

 

[Shortround6]

As a wild guess could the US figures be counting nitrous oxide?

My German is way too terrible to attempt any sort of translation but it might make sense of the difference in the power curves at high altitude?

 

[Deleted member 68059]

As a wild guess could the US figures be counting nitrous oxide?

There are no GM1 occurances on those graphs. They would produce an instant vertical power increase, not an extension of the existing line.

That power for 603N roughly overlaps my photos of original DB papers as showing the maximum output possible. However its basically impossible to produce any "single" graph for this engine as it was in several different developmental levels at the time of the collapse - my information states most, if not all of which still in single-cylinder form. Hence the charts will be all very different, and moderately innacurate as its pretty tricky extrapolating output from
one to 12 cyls - expecially with a new and very different version for which no good baseline exists.

Very interesting, especially the 1st picture. Is the source available on-line?

The top graph is a typed version of the original German microfilm - which is at NASM-UDVAR Hazy - Microfilm Reel#3400 Frame 536.
My copy of it is fairly poor as they have no digital reader there, and so I had to photograph the screen of the reader - its that or you buy
the reel !

The abstract reads:

"This limited investigation concerns the engine performance of the DB603, DB603N and 4 jet engines at high altitudes. On flights of more than 4 hours duration the conventional engines were superior. At 2 hours endurance the superiority of the conventional engines exists at over 13km and at under 1hr it exists under 11km. This figure being reduced to 9km under emergency output conditions. Data chartes are included and further development of conventional engines is recommended"

The bottom graph is indeed from the Gersdorff book - on page 107. However there is no reference given for that actual graph. It appears to me to be a graph from a booklet printed by Fritz Nallinger of DB in late 1941, with the later 603 engines added on later. Hence why it still includes the power of the DB600 - alongside the 603N, with which it bears almost no resemblance at all, which would make very little sense for an original chart.

View media item 25575