Advanced French Fighters vs 1942/1943 contemporaries (3 Viewers)

[TM06]

For the 14R, this was of no interest since this engine's supercharger (in its second version with axial entry, from the 14R 04/05) had very high performances, with an efficiency close to 80%.

For a frame of reference and out of curiosity; how does that 80% efficiency rating compare to other superchargers around the world during the same time period, on radials or otherwise?
From everything I've read, I'd imagine it would be a good bit better than the 801's supercharger and leaps and bounds better than the superchargers on Italian radials.

 

[Bretoal2]

For a frame of reference and out of curiosity; how does that 80% efficiency rating compare to other superchargers around the world during the same time period, on radials or otherwise?
From everything I've read, I'd imagine it would be a good bit better than the 801's supercharger and leaps and bounds better than the superchargers on Italian radials.

In the 1930s, it was quite difficult to compare the actual efficiency of superchargers from one country to another because the standards and test protocols were often quite different.

This difference in procedures is indicated by this American report (among many others) on the Planiol-Szydlowski S/C :

Szydlowski-Planiol Supercharger

In the particular case of the Gnome & Rhône 14R 2-speeds S/C with axial entry, the same laboratory (Etablissement d'Essais des Moteurs, or EEMo, in Saint-Etienne in the "free zone") tested this S/C in the summer of 1942, as well, with same protocols and installations, as the Turboméca models (Planiol-Szydlowski) intended for the Hispano-Suiza 12Y and 12Z. The resulta are that the G&R S/C is almost as good as the Turboméca one.

The 80% value recorded by the EEMo is among the highest known in France at that time.

It is said that after the Bloch 157 was sent back to Villacoublay, its 14R engine was dismantled and sent to Germany, one may wonder if this S/C (more than any other parts of this engine...) with good efficiency was not of interest to DVL or BMW (BMW managed the Parisian factories of Gnome and Rhône). I have no proof, it is a simple hypothesis !

 

[Elan Vital]

In the 1930s, it was quite difficult to compare the actual efficiency of superchargers from one country to another because the standards and test protocols were often quite different.

This difference in procedures is indicated by this American report (among many others) on the Planiol-Szydlowski S/C :

Szydlowski-Planiol Supercharger

In the particular case of the Gnome & Rhône 14R 2-speeds S/C with axial entry, the same laboratory (Etablissement d'Essais des Moteurs, or EEMo, in Saint-Etienne in the "free zone") tested this S/C in the summer of 1942, as well, with same protocols and installations, as the Turboméca models (Planiol-Szydlowski) intended for the Hispano-Suiza 12Y and 12Z. The resulta are that the G&R S/C is almost as good as the Turboméca one.

The 80% value recorded by the EEMo is among the highest known in France at that time.

It is said that after the Bloch 157 was sent back to Villacoublay, its 14R engine was dismantled and sent to Germany, one may wonder if this S/C (more than any other parts of this engine...) with good efficiency was not of interest to DVL or BMW (BMW managed the Parisian factories of Gnome and Rhône). I have no proof, it is a simple hypothesis !

Have you already looked into the safran group database here: Media Library Patrimoine ?

I just realized today that they might have relevant info on the Hispano and G-R engines as well as Turboméca S-C, and indeed there are some Turboméca trials in 1942-44 and here some Gnome-Rhone trials.

 

[Bretoal2]

Have you already looked into the safran group database here: Media Library Patrimoine ?

I just realized today that they might have relevant info on the Hispano and G-R engines as well as Turboméca S-C, and indeed there are some Turboméca trials in 1942-44 and here some Gnome-Rhone trials.

The documents that I quote above come from this site.

 

[tomo pauk]

For a frame of reference and out of curiosity; how does that 80% efficiency rating compare to other superchargers around the world during the same time period, on radials or otherwise?
From everything I've read, I'd imagine it would be a good bit better than the 801's supercharger and leaps and bounds better than the superchargers on Italian radials.

FWIW, the S/C on the G&R 14R 05/05 was delivering 1180 mm Hg at 5000m (for 1580 HP at 2600 rpm), or ~46.50 in Hg, or about 1.61 ata; no ram effect in all cases.
The S/C of the BMW 801D was delivering ~1.55 ata at 5000m with tad of ram (for 1550 HP at 2700 rpm), at least when going with this chart. In the second gear at 5000-5500m, it looks like the difference of ~0.05 ata was 'worth' some 50 HP on the BMW 801D.
The 14R was not just turning lower RPM, but was also a much lighter engine than the 801 (that was probably over-built?), and also of the smaller displacement, while making better altitude power - kinda shows the importance of having a top-notch S/C. Granted, a sound military strategy >> a good S/C.

 

[tomo pauk]

In the particular case of the Gnome & Rhône 14R 2-speeds S/C with axial entry, the same laboratory (Etablissement d'Essais des Moteurs, or EEMo, in Saint-Etienne in the "free zone") tested this S/C in the summer of 1942, as well, with same protocols and installations, as the Turboméca models (Planiol-Szydlowski) intended for the Hispano-Suiza 12Y and 12Z. The resulta are that the G&R S/C is almost as good as the Turboméca one.

The 80% value recorded by the EEMo is among the highest known in France at that time.

It might've been that French over-stated the efficiency of that S/C?
Eg. RR has never beaten the 75% efficiency on their superchargers, after many years of development (per this article, fig. 11). We know that Merlin XX was good for about +10.5 psi at 16000 ft (ie. about 1.77 ata at 5 km), with a S/C that was rated at 75% efficiency max at 2.5.1 pressure ratio (cue the S/C o the Merlin 50).
DB lines for were limited at 75% on their superchargers' maps for the DB 603A and 601E.

Granted, French methodology was possibly different than that of what the British or the Germans used. If that was the case, in a direct comparison and with the same methodology, either these other S/Cs are over 80% best-case, or the French S/C is under 75%.