Vertical Speed Indicator

Question 1

What does a VSI do?

Answer 1

Measurement of vertical speed!

Question 2

How does a VSI work in principle?

Answer 2

change of static pressure over time.

opposed to a altimeter which has a immediate static responce.

Question 3

How does a VSI work mechanically?

Answer 3

static pressure is fed to a differential capsule and into the surrounding case.

a restrictive capillary delays the static flow and thus converts the delayed response into a mechanical movement of the capsule.

a bimetallic strip responds to reduced temp at alittude and allow more air to flow at less dense altitudes.

Question 4

What is an IVSI, what does it do and how does it work?

Answer 4

Instananeous Vertical Speed Indicator.

Counteracts time lag between clim/descent and read-out.

uses accelerometer ‘pistons’ to give instant responce. This is further dampened to prevent over-reading.