Hispano-Suiza 12 Xbrs

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YavorD

Airman
16
10
Oct 11, 2008
Sofia
A question, please!
Any clue where to look for a sea level / altitude performance curves for a Hispano-Suiza 12 Xbrs?
Best regards,
Yavor

P.S. The same question for HS 12 Xcrs, too. Thanks!
 
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Thank You very much, Sir!
I am looking for something like the following example (HS 12 Xirs). According to the data page from Your post, the HS 12 Xcrs should have the same performance as 12 Xirs, only 10 kg heavier.
Best regards,
Yavor

 
I believe the only real difference between the Xirs and Xcrs is that the the Xcrs had a modified reduction gear case and a prop shaft with a through-hole in order to allow a motor cannon to be mounted with the barrel through the prop shaft.
 
Thank You very much again, Sir!
I am trying to understand how early supercharged engines in early 1930-ies influenced the aircraft design. Attached below is a preliminary, "quick and dirty" model of the Blériot SPAD 510. As much I found no data for the propeller used, and engine data are far from complete as well, the model is built with a constant speed prop. What I learned at this early stage, the aerodynamics of this aircraft is very similar to another André Herbemont design, Blériot SPAD 81 C1 with a Hispano-Suiza 8 Fb engine.
 
I believe the only real difference between the Xirs and Xcrs is that the the Xcrs had a modified reduction gear case and a prop shaft with a through-hole in order to allow a motor cannon to be mounted with the barrel through the prop shaft.

Perfectly true. See post #3, pic last line : "Entr'axe des pignons du réducteur" i.e. center distance of reduction gear, 210 mm for 12Xirs, 270 mm for 12Xcrs. Basically same engines with same performances, the only difference is in the "moteur-affut" arrangement. .
 
The SPAD.510 had a two bladed, fixed-pitch propeller. I have not identified the model.
Agreed. From the pictures, the prototype used a metal, ground adjustable propeller, most probably Ratier, production series machines were equipped with a wooden propeller, most probably Chauvière. I used a variable pitch propeller in the model in order to collect data about optimal advance ratio and diameter of the propeller.
The engine model is improved now. I tried to use the propeller data from Dewoitine 500 but the propeller is not very good on a SPAD 510. The rate of climb and ceiling came significantly lower than data for the prototype Blériot SPAD 510 as shown on the plot above. With a reduction ratio of 2:3 (14 / 21) the propeller shaft speed is quite low.
It will take some time to find the optimal diameter, advance ratio and solidity for the propeller.
Best regards,
Yavor
 
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Thank You, dear readers!
This is how the current Blériot SPAD 510 (prototype) model looks with a ground adjustable propeller.
Speed, rate of climb and time to altitude plots shown. The model is in better shape now but still work in progress.

References:
  1. Revue des forces aériennes 44 1933-03, pp. 339-342
  2. Revue des forces aériennes 47 1933-06, pp. 669-673
  3. L'Aéronautique 164 1933-01, pp. 4-6
  4. L'Aéronautique 175 1933-12, pp. 266, 273-274
  5. Revue de l'Armée de l'Air, 65 1934-12, p. 1457
  6. La Technique Aéronautique 139 1936(1)






 
1) I think the third graph is not "rate of clim", but "time to altitude".

2) On the first graph, what are the dotted lines ? And the blue dotted lines ?

3) Same first graph, what is the strange part ot the speed curve, grayed below ?
 

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1) I think the third graph is not ...
Thank You!
1) corrected axis title
2) large-dot line in the middle of the bell-shaped curve is the speed for a maximum rate of climb, max continuous power; blue set of dotted lines show the effect of using take-off bust setting, 960 mm Hg instead of 880 mm Hg;
3) left hand side of the bell-shaped curve is the true air speed at maximum lift, full power on approach to stall, if there is excess power, or just the minimum speed to fly at constant altitude (about approximately 7700 metres).
Best regards,
Yavor

 

Thanks.

I think the two sides of the "bell" curve should not have the same aspect - let's say, the same color.

Otherwise, interesting post. And remember the VG-30, as Potez 230, were announced with 500 km/h top speeds (or about) with the same engine....
 
...

I think the two sides of the "bell" curve should not have the same aspect - let's say, the same color.

...

For me the curve represents a theoretical "1-g flight envelope". The aircraft will be in a transient state outside this envelope. Naturally one can draw such a shape for any chosen g-number and it is a step in the process of calculation of an instantaneous and a sustained rate of turn, as an example.
 

OK for the "1g - flight envelope", but add these words to the legend !
 

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