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Is this a model that was used on other aircrafts of the era, too? Looking for technical information about it and knowing the manufacturer and model number would make that easier.

The Interim Flight Manual says that "the sphere, receiving information from the auxiliary gyro platform system, is free to rotate 360 degrees about all axes". So it is truly a complete sphere? In what situations would it rotate significantly around the "polar" axis and show its "west", "east" or even "back" side? As can be seen in this image, the lower and upper regions of the sphere have compass directions. Are those parts rotating independently from the middle region, to show heading? There is a small gap that seems to indicate that possibility.

enter image description here

Edit: I now notice that the Interim Flight Manual describes a different kind of ADI than what the aircraft in the museum has. It looks quite different in this figure:

enter image description here

This kind of ADI probably indeed had a fully rotating complete sphere. At some stage that was apparently exchanged with the model that the first photo shows. In that I guess only the separate top and bottom segments (with the heading directions) are complete and rotate 360 degrees to show headings.

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  • $\begingroup$ (This is from the USAF museum's fabulous 360 degree (the nerd in me wants to write 4π steradians) cockpit photo at nmusafvirtualtour.com/cockpits/RD_tour/RD-9.html ). The gyro compass below the ADI also shows the same 210 degrees heading, so that does indeed seem to have been the heading when the aircraft's systems were shut down the final time.) $\endgroup$
    – tml
    Commented Nov 8, 2021 at 19:51

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The Mirage III had this kind of spherical indicator, combining attitude and heading indicators, known as Bezu ball, after its inventor:

enter image description here

Source.

So it is truly a complete sphere?

Yes.

enter image description here

Source.

In what situations would it rotate significantly around the "polar" axis and show its "west", "east" or even "back" side?

The instrument combines an attitude indicator and a heading indicator. The AI changes the up/down axis orientation, then this axis rotates to indicate the heading.

enter image description here

Source. This one was manufactured in 1957.

I believe it was customized by SFIM, a French company developing instruments under a Sperry license, for Dassault and not used by other manufacturers.

The ball was reused for Mirage IV and 2000, integrating more indications. Manufactured by SFENA and SFIM and known as synthesizer Chombard, still after its inventor. SFIM merged witin Safran in 2005.

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