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    Re: Kollsman Periscopic Bubble Adjust
    From: Frank Reed
    Date: 2022 May 13, 11:01 -0700

    Noell Wilson, you wrote:
    "I asked about CelNav and he went into detail about the multiple electronic systems they had and, said they didn’t do CelNav any more, and didn’t need it. I said “Unless you have a lightning strike.” He just shrugged."

    Maybe he shrugged because they were hit by lightning on their previous flight! :) Aircraft, including commercial airliners, are struck by lightning on a regular basis. Here are a couple of links with more details:

    You wondered if the USAF has "rediscovered CelNav". As for manual CN with handheld sextants? Highly unlikely in almost any realistic context outside Antarctica. But automated CN has been around since the 1970s (even earlier in astro-inertial systems on ballistic missiles). Automated CN was never given up and continues to have some value, especially for aircraft flying in the stratosphere where clouds are few and the stars are easy to see day and night. Details are classified, of course, but rumor says the US Air Force's automated celestial systems are nearly as accurate as GPS and produce fixes within seconds, like GPS. The B2 has an automated celestial system under a dome on the wing, and I imagine its successor, the B21, will also. A team at the US Naval Observatory was tasked some decades ago with working out a variable refraction correction based on the pressure profile above the airfoil on the B2.

    Frank Reed

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