Date: 01 Dec 96 04:08:52 From: firstname.lastname@example.org (Al Moyes) Organization: [not set] References: 1 Followups: 1
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In message <airliners.1996.2519@ohare.Chicago.COM>, Ed Hahn <email@example.com> wrote: > Now then, the reason the IRS supplies the Vertical Speed (VS) is > that, while the vertical accelerometer CANNOT provide raw VS output, > it CAN provide enough of a "smoothing" signal to the Altitude Rate > signal to allow the cockpit instrument to not lag behind the > aircraft. (See Appendix below.) > > Note that the cockpit instrument is most properly known as the > "Inertial-lead Vertical Speed Indicator", but is more commonly known > as the "Instantaneous Vertical Speed Indicator". As I understand it the Instantaneous VSI (or inertial lead VSI) is a complete instrument in itself and does not rely on accelerometers from the IRS but has its own. I may be way out of date but certainly I was taught that the IVSI had two pistons on springs that were fed static pressure. When the pressure changed the inertia displaces a piston which produces a pressure differential which immediately registers on the dial. As the effect from the piston fades the actual static pressure change from the metering unit will take over. -- Al Moyes firstname.lastname@example.orgNET.co.uk "NEVER lost, just uncertain of my position"