View Full Version : British Aircraft Engines in WWII

06-26-2005, 09:11 AM
...AND NOT ONLY BRITISH (US and SOVIET engines added)

S! All,

I've just ran into an interesting chart with WWII engine specifications. It was published in a Czechoslovak magazine "Letectvi" (Aviation) in 1945, just after the war. It's outdated, but hopefully not completely wrong.


(from an article "Engines of the Victors and the Defeated" by V. Karmazin in Letectvi, Oct. 1945)

Edit: added new data on Bristol Centaurus engine (red figures)



(from "USA Engines in the War" by V. Karmazin, Letectvi, Feb 1946)



(from "USSR Engines in the War" by V. Karmazin, Letectvi, Apr 1946)

(Note that the columns with engine performance data differ from the remaining two charts. Nominal is instead of Maximum and Cruise is instead of Nominal.)


I only wrote what was in the charts. I will appreciate any comments, especially to English terminology (not my strength, ehh..).

There was some confusion regards the units of mean fuel consumption. It happened due to lack of my attention during translation, I apologize for that. The unit is grams of fuel per HP produced and hour of operation http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif


06-26-2005, 09:31 AM
sweet graph http://forums.ubi.com/images/smilies/11.gif, think i need a bigger moniter http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

what words do u not understand? i will try and translate them for you http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

06-26-2005, 09:53 AM
what words do u not understand? i will try and translate them for you http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

It's translated from Czech, so I don't know whether you can help me unless you're Czech or Slovak.

I'm not sure about the term "volumetric compression ratio" that I used. I mean with it the ratio between the volumes under the piston in the "upper" and "lower" position (Czech: "objemovy kompresni pomer")

By "displacement" (Czech: "zdvihovy objem") I mean the diffence in volume under the piston in these two positions.

In the magazines (I have the entire 1945 and 1948 years), there are lots of information on engines, wing profiles, early jet development, propellers, designs... with tons of charts and images. I'd like to translate something for you (not only you Pingu http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif), I just don't know what is most interesting.

06-26-2005, 11:11 AM
i think the compression ratio is how much the air is compressed in the cylinder and possibly in the supercharger too.

displacement is how big or area something takes up or can hold.

for example your 2 litre bottle of coke at home has a displacement of 2 litres.

personaly id be most interested in the engine information you have http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

06-26-2005, 11:38 AM
Normally it's just called "compression ratio" in English. Otherwise you've translated it correctly. It's the ratio of the volume above the piston at bottom dead center to the volume above the piston at top dead center.

"Zdvihovy objem" probably translates to "swept volume." (Online translators say "jump size." Bah, useless.) Swept volume (the volume the pistons move through during a full stroke) and displacement (the total volume of fuel/air mixture drawn in during a complete cycle) are equal in piston engines, so you've translated that correctly as well. I believe the values you've given are the correct displacement values, in any case.

06-26-2005, 11:52 AM
Thanks NonWonderDog, your post is exactly to the point.

I wrote volumetric compression ratio (used for internal combustion engines) to make a difference from pressure compression ratio which is used in describing gas turbines.

06-27-2005, 07:59 AM
Now that's a good thread http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif Utchoud, I'm also interested in British aircraft engines, if you check my signature you can deduce why http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

At crossandcockade.com (http://www.crossandcockade.com) you can find a document <A HREF="http://www.crossandcockade.com/files/UK%20ENGINES.doc" TARGET=_blank>AERO-ENGINES EXHIBITED & STORED IN THE UNITED KINGDOM & IRELAND (May 2003 issue)
</A> - which serves as excellent guide for museums that have British engines in their collections.

You can find helpful people at Aircraft Engine Historical Society (http://www.enginehistory.org) and Rolls-Royce Heritage Trust (http://www.rolls-royce.com/history/default.jsp)

06-27-2005, 08:11 AM
Compression ratio is as follows.

Swept volume divided by the volume
of the head chamber.

Stroke multiplied by the area of the bore cross section
then divided by the chamber volume.

The piston to deck and head gasket are usually
accounted for in the equation as the volume
of the assembled piston to deck clearance
using the same furmula as for calculating stroke.

Note, a lot of aircraft engines had no head gaskets
or, in the case of RR built Merlins, no seperate

So it goes like this. Add the combustion chamber
volume to the piston deck volume.
Divide the swept volume by the sum and you got
the gross compression ratio.

Supercharger pressure is not figured into the
advertized compression ratio.
It is however a real life factor in total compression.


06-27-2005, 08:43 AM

On this chart, figures for horsepower for many of the engines are not peak horsepower, but rather normal power ratings.

06-27-2005, 09:00 AM
We should also ask: which horsepower? Metric or Imperial? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

1 hp (Imperial) = 1.0139 hp (metric) = 0.7457 kW
1 hp (metric) = 0.7354 kW

06-27-2005, 09:38 AM
S! Thanks for your replies guys,

Honestly, I don't know which horsepower it is (I didn't know there are two kinds of horsepower anyway http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif) The chart was published in a Czechoslovak magazine, I would therefore expect metric hp. However, the author might have (and probably did) used original data from e.g. British source, in Imperial units. If he didn't know the difference, he also didn't make the small conversion.

Many of the data may be unprecise, you may find better ones. However, such a "complete" chart is not seen very often, I think, so I posted it.

If you're interested, we may attempt to make it complete with up-to-date resources that we have access to. Pre-war British engines (useful for Rola, http://forums.ubi.com/images/smilies/25.gif to your project!), and not only they, are left out. After some dozens of posts http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif we may have a good chart of British engines and everyone who is intersted in this thing could use it for any purpose.

06-27-2005, 02:25 PM
Nice! i wish you could find similar chart for german, american and russian engines http://forums.ubi.com/images/smilies/11.gif

06-28-2005, 08:34 AM
I've just added a chart of US engines. I'm going to upload also the Russian ones (a bit smaller chart, however). In the British chart, I also added one column (work cycle).

Unfortunately, I have no such chart of German engines - perhaps somebody else could help. The author of the article obviously favored http://forums.ubi.com/groupee_common/emoticons/icon_mad.gif side over http://forums.ubi.com/images/smilies/51.gif side.

06-28-2005, 09:25 AM
http://forums.ubi.com/images/smilies/25.gif http://forums.ubi.com/images/smilies/11.gif @ new chart http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

06-29-2005, 06:42 AM
Notable omission is

The Allison V-3420.

The P&W R-4360

The Lycoming XR7755

The Wright Tornado (no photo link yet)

MLChttp://www.wpafb.af.mil/museum/engines/eng3.jpg http://www.wpafb.af.mil/museum/engines/eng34a-1.jpg http://www.aviation-history.com/engines/xr-7755.jpg

06-29-2005, 07:19 AM
Originally posted by MoeLarryCheese:
Notable omission is...

Exactly, the chart has some limitations. The author admits in the article that he has only included mass-produced engines for mass-produced aircraft. Note also the date and location of publication - information on the newest or prototype engines was very limited at that time in Czechoslovakia. (I was also thinking of the R-4360 - That's what I call an engine!)

<span class="ev_code_YELLOW">If anyone has some good documentation, technical specifications, pictures, links etc. on WWII engines, please post them here - I'd like to add your data to the chart.</span>



07-03-2005, 02:52 PM
S! All,

I've added the Soviet engines as promised. Also done minor changes in the British chart.

As there's not much response to my idea of completing the charts, I don't intend to continue it.



07-03-2005, 03:03 PM
http://forums.ubi.com/images/smilies/25.gif http://forums.ubi.com/images/smilies/11.gif
thankyou for your efforts http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

07-03-2005, 10:59 PM
Originally posted by Rola.:
We should also ask: which horsepower? Metric or Imperial? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

1 hp (Imperial) = 1.0139 hp (metric) = 0.7457 kW
1 hp (metric) = 0.7354 kW


SAE Net Horspower In 1972,

American manufacturers phased in SAE net horsepower. This is the standard on which current American ratings are based. This rating is measured at the flywheel, on an engine dyno, but the engine is tested with all accessories installed, including a full exhaust system, all pumps, the alternator, the starter, and emissions controls. Both SAE net and SAE gross horsepower test procedures are documented in Society of Automotive Engineers standard J1349. Because SAE net is so common, this is the standard we will use to compare all others.

SAE Gross Horsepower.

This is the old process that American manufacturers used as a guide for rating their cars. It was in place until 1971. SAE gross also measures horsepower at the flywheel, but with no accessories to bog it down. This is the bare engine with nothing but the absolute essentials attached to it; little more than a carb, fuel pump, oil pump, and water pump. Because the test equipment on the engine is not the same as in SAE net, it is impossible to provide a mathematical calculation between SAE net and SAE gross. As a general rule, however, SAE net tends to be approximately 80% of the value of SAE gross. SAE J245 and J1995 define this measurement.

DIN Horsepower

This is a standard, DIN 70020, for measuring horsepower that very closely matches SAE net. The conditions of the test vary slightly, but the required equipment on the engine and the point of measurement (flywheel) remains the same. Because the test conditions are so similar, it is safe to divide DIN horsepower by 1.0139 to arrive at SAE net. This value is so close to equal that for all but the most technical purposes DIN and SAE net are interchangeable.

07-05-2005, 04:16 PM
Something is fishy. RR Griffons, both single and two stage have the same lenght, and both are shorter than the smaller Merlin ? Oh come on.

07-06-2005, 11:31 AM
Thread was moved.

Originally posted by Kurfurst__:
Something is fishy. RR Griffons, both single and two stage have the same lenght, and both are shorter than the smaller Merlin ? Oh come on.

I completely agree with you... I searched in the web but all I found was a statement that "the Merlin and the Griffon were similar in size". All I can say is that the Spitfire Mk.XII was 0.24 m longer than Mk.IX and Mk.XIV was 0.39 m longer.

It seems that the charts are not much worth after all, but at least they may be useful when no other data are available.



07-06-2005, 11:41 AM
"By clever positioning of the components, the designers kept the length of the Griffon to within 3" (7.5cm), and the weight within 600lb (272kg) of the equivalent figures for the Merlin"

Source, Great Aircraft of WWII. The Spitfire section written by Alfred Price.

07-06-2005, 01:43 PM
the griffon was well "packaged" vs the merlin.

still, not much compaired to the jaw droping audacity of napier engine design http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

07-06-2005, 01:50 PM

griffon on the top, merlin below, and erm me.

not the best pic im afraid..


db603, probably in its orignal transport box frame thing http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

http://premium1.uploadit.org/pingu666//SIMG8009edit.jpg nomad

http://premium1.uploadit.org/pingu666//pinguandnapire.jpg the 1 ton monster, the sabre.

http://premium1.uploadit.org/pingu666//madengine.jpg one of the engines before the sabre, cant remmber its name http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif

07-06-2005, 08:14 PM
i wish i had the 24 cylender napier motor pic i had when i was at the aviation museum in Ottawa Canada, but i can guarantee you that thing is friggin huge (reformatted recently)

07-06-2005, 08:27 PM
yeah its a solid lump, im not sure what its frontal area is tho http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

excellent design tho, czech out the huge tempest thread for a good read on it http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

07-06-2005, 10:11 PM
p1ngu 666, could this be the engine?

From Jane's Fighting Aircraft of WWII:
"In 1927 a new line of development in aero-engine design was begun, that of the air-cooled in-line double-crank engine, and the Rapier and the Dagger series of engines followed.
Both the Rapier and the Dagger were air-cooled vertical H-type engines, the former with sixteen cylinders and giving a maximum output of 395 h.p., and the latter with twenty-four cylinders and developing a maximum output of 1,000 h.p."

From the photo you posted, I think it's a Dagger. Cool looking engine.
Where in the world did you find all these engines? Looks like quite a collection.

MoeLarryCheese, the book the above information came from is a re-print of the 1946 issue of Jane's All the Worlds Aircraft. In 1945 and early 1946 the performance figures for several of the engines, including the ones you mentioned, were still regarded as secret, therefore, no information would have been available for publication.

07-06-2005, 10:21 PM
Do any of you with engines books in your libraries have any info on Rolls-Royce's Crecy?

07-07-2005, 03:46 AM
I think it can be the Dagger, but I'n not sure.

Dagger VIII was used on Handley-Page Herefords, a variant of the Hampden, which normally had Bristol Pegasus XVIII engines. The smaller Rapier VI was used on Fairey Seafox seaplane. You can find them both in the chart http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

As for RR Crecy... never heard of http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

07-07-2005, 12:59 PM
sounds like its the dagger http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

"Crecy €" V12, 90?, sleeve-valve, liquid cooled, 26.1 litre, supercharged, two-stroke, mechanical fuel injection (from Focke Wolf 190) Otto-engine. The 1942 prototype had surprisingly low fuel consumption at the highest power output. In December of 1945, after eight years of development, work on the Crecy was terminated. At that time the Crecy was capable of double the horsepower of conventional 4-stroke designs of the same displacement. Only six Crecy engines were built, all with even serial numbers (2, 4, 6, 8, 10 and 12). This has led to confusion as to the numbers made. Crecy engine #10, achieved the highest test horsepower in December 1944, putting out the equivalent of 5,000 brake horsepower."

sadly, source webpage got other stuff wrong but o well http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

07-07-2005, 03:16 PM


07-07-2005, 05:51 PM
Nice work Utchoud!Anyone got any idea what the fuel consumption units mean-gal/hp "hod"?Whats hod mean?

07-08-2005, 06:26 AM
Originally posted by ytareh:
Nice work Utchoud!Anyone got any idea what the fuel consumption units mean-gal/hp "hod"?Whats hod mean?

I'm sorry, I should have clarified it there. Mean fuel consumption in the chart is given in grams of fuel per horsepower produced and hour ("hod") of operation.

"Hour" is "hodina" (hod) in czech, I forgot to translate it http://forums.ubi.com/images/smilies/35.gif I'm correcting it now.

07-11-2005, 07:23 AM
Sorry for returning this thing back to the top, but I think it's better than starting a new thread just for this.

I finally found some information on Merlin and Griffon engine dimensions, discussed above. Published in the same magazine as the charts, but about half a century later (1992).

Merlin 66

Length: 1.98 m (chart: 2.160 m)
Height: 1.11 m (chart: 1.200 m)
Width: 0.76 m (chart: 0.758 m)
Mass: 746 kg (chart: 745 kg)

Griffon 65

Length: 2.06 m (chart: 1.960 m)
Height: 1.14 m (chart: 1.050 m)
Width: 0.75 m (chart: 0.758 m)
Mass: 947 kg (chart: 940 kg)

Don't take the data in the chart too seriously http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif