Spherical Attitude Indicators

Icaro

Well-Known Member
I've seen these in pictures of military jets, the X-15, Apollo and space shuttle. The AI is a sphere. My question is what is the sphere representing (beyond just pitch and bank information that we see on GA aircraft)?
 

MikeD

Administrator
Staff member
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I've seen these in pictures of military jets, the X-15, Apollo and space shuttle. The AI is a sphere. My question is what is the sphere representing (beyond just pitch and bank information that we see on GA aircraft)?

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The ADI is the same, just without the inherent limitations of the non-spherical ones. Designed to provide constant info for highly-maneuverable aircraft. In a loop, for example, you get constant accutate pitch info throughout.
 

MikeD

Administrator
Staff member
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INS/IRS makes this a possibility, correct?

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Not really, but let me elaborate. Aircraft like the T-38, for example, have these ADIs without any INS. When I say constant updates of info, I mean that because the ADI is a sphere or rotating ball, there's no "limit" to it's movement, so to speak. Do a loop with a standard AI, you will eventually reach a pitch limit where the AI is no longer providing any useful info, and will likely tumble. The sphere ADI doesn't do this. Regards INS, they don't "talk" to the ADI, for attitude info, but may "talk" to the ADI in so far as the "D", or director portion of the ADI, the portion that gives nav info. I'm mainly referencing the spherical ADI in it's strict pitch/bank reference sense.
 
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