Vertical speed indicator

Question 1

principles of VSI?

Answer 1

senses rate of change in static pressure in fpm or m/s

uses a logarithmic scale for greater accuracy at lower values

Question 2

vsi operation

Answer 2

compares ambient pressure fed into capsule to a delayed value of static pressure fed in from a metering unit(causes lag) into the case

Question 3

VSI in climb

Answer 3

static decrease
capsule contracts
rate of climb depends on difference
level off- pressure stops changing

Question 4

VSI errors

Answer 4

IMP

lag- small delay between what aircraft is doing and what is indicated

Question 5

IVSI

Answer 5

has no lag- due to having a dashpot or accelerometer unit

provides instantaneous reading

Question 6

IVSI errors

Answer 6

IMP
turning error- false climb indication
sensitivity to turbulence- erroneous readings

Question 7

VSI blockage

Answer 7

blockage in the static line will show frozen reading of 0fpm

Question 8

VSI leaks

Answer 8

unpressurised- momentarily rate of climb
pressurised- show rate of descent until pressure equals to cabin alt. becomes a cabin VSI as only shows changes in cabin alt from then

Question 9

Rate of descent=

Answer 9

5 x ground speed(its)