French WW2 Engines (1 Viewer)

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Laurelix

Airman 1st Class
253
138
Jun 13, 2016
So I came across this on google images although don't know the source.
A254-E646-9-BE7-4336-B9-D4-CBEAF5-CF9-FBE.jpg


Notice how it states their Nominal Power at Sea Level and WEP power at sea level.

I was looking for this except that I was looking for it for HS 12Ycrs engine.

Does anyone have any documents for this engine?

I know that it has 835hp at SL with WEP but I don't know the nominal power of it at sea level.
 
Whenever I see someone is quoting WER figures for non-American engines, it is time for face-palm.
Anyway:
I have a book about Avia B-135 which used HS 12Ycrs and it states 860hp at 4000m and that the plane achieved 527km/h at 4000m during top speed tests.

Your source states 868hp at 2400 metres...
Am I missing something?
 
I have a book about Avia B-135 which used HS 12Ycrs and it states 860hp at 4000m and that the plane achieved 527km/h at 4000m during top speed tests.

Your source states 868hp at 2400 metres...
Am I missing something?

Yes, you missed that HS 12 Ycrs1 is not HS 12 Ycrs...

The 12 Ycrs1 was a 12 Ycrs with reduced diameter supercharger (in order to improve low-altitude performance). And 12 Ycrs was rated at 860 cv @ 4.000 m with 880 mm Hg boost (an 835 cv for TO).

Regards
 
Yes, you missed that HS 12 Ycrs1 is not HS 12 Ycrs...

The 12 Ycrs1 was a 12 Ycrs with reduced diameter supercharger (in order to improve low-altitude performance). And 12 Ycrs was rated at 860 cv @ 4.000 m with 880 mm Hg boost (an 835 cv for TO).

Regards
So how does it differ to HS 12Ybrs and HS 12Ydrs bevause both are 835hp at SL and 860hp at 4000m
 
HS 12 Ybrs = early version, "engine study HS73"
HS 12 Ydrs = improved version with provision for variable-pitch propeller
HS 12 Ycrs = same as 12Ydrs, but "HS77" family, incorporating a raised propeller shaft to give "moteur-canon" or "moteur-affût" arrangement.

All three engines gave same TO power, nominal power and critical altitude (same performances, if you like !)
And 12 Ycrs1 = same as 12 Ycrs, with derated supercharger, boosting low-altitude performance.

The "Tabulated data from Lage 2004" incorporated in the Wikipedia english notice of Hispano-Suiza 12 Y contains many errors and misreadings.

You must read the French version (I wrote it !)

Regards,
 
HS 12 Ybrs = early version, "engine study HS73"
HS 12 Ydrs = improved version with provision for variable-pitch propeller
HS 12 Ycrs = same as 12Ydrs, but "HS77" family, incorporating a raised propeller shaft to give "moteur-canon" or "moteur-affût" arrangement.

All three engines gave same TO power, nominal power and critical altitude (same performances, if you like !)
And 12 Ycrs1 = same as 12 Ycrs, with derated supercharger, boosting low-altitude performance.

The "Tabulated data from Lage 2004" incorporated in the Wikipedia english notice of Hispano-Suiza 12 Y contains many errors and misreadings.

You must read the French version (I wrote it !)

Regards,
Thx but what's the nominal power at SL?

if that HS 12Ycrs has 890 CV at SL at take off and 820 CV at SL at nominal, would it be incorrect to conclude that the normal version had
835 CV at take off and 770 CV at nominal?

890 / 820 = 1.085366
835 / 1.085366 = 770
 
Last edited:
Thx but what's the nominal power at SL?

if that HS 12Ycrs has 890 CV at SL at take off and 820 CV at SL at nominal, would it be incorrect to conclude that the normal version had
835 CV at take off and 770 CV at nominal?

890 / 820 = 1.085366
835 / 1.085366 = 770

Bingo ! (or near miss...) The rated normal power at SL for 12 Ycrs/drs was 760 cv.

Note that 4.000 m. figure for critical altitude is not totally true. In fact, the designed critical altitude was 3.300 m. This was also given by bench testings and type-test.

BUT... many French companies preferred to give also the "puissance en altitude" where critical altitude was boosted by ram effect in the carburetor intake ! And so the was the 12 Ycrs... We see that Avia B-135 maximum speed was at 4.000 m - would the bench critical altitude be truly 4.000 m, the "real life" maximum speed should have been mesasured at higher altitude !
 
Thanks :)
Here's a Bulgarian speed test results for Avia B-135
A5-C81642-06-DC-4-D4-E-9606-A30-D07-D2-E151.jpg

462km/h at Sea Level
478km/h at 1000m
495km/h at 2000m
511km/h at 3000m
527km/h at 4000m
529km/h at 4150m
519km/h at 5000m
507km/h at 6000m
 

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