Vertical Speed Indicator

Question 1

Does it require a pitot and Static source?

Answer 1

Pitot - no
Static - yes

Question 2

What scale does it use?

Answer 2

Logarithmic.
Senses rate of change of static pressure.

Question 3

Operation in a climb?

Answer 3

Static pressure decreases inside the capsule and the capsule contracts.
Rate of climb depends the difference between case and capsule pressure.

Question 4

Operation - level off?

Answer 4

Pressure in capsule stops changing, pressure in the case takes a few seconds to catch up. Equal pressure = 0fpm.

Question 5

VSI lag?

Answer 5

Small time delays between what aircraft is doing and what is indicated.

Question 6

Instantaneous VSI?

Answer 6

Accelerometer-unit metering-unit Dashpot.

Question 7

ISVI operation - descent

Answer 7

Artificially high ambient pressure in capsule.
Relatively low pressure in case.

Question 8

ISVI operation - climb

Answer 8

Opposite

Question 9

ISVI errors

Answer 9

Instrument
Manoeuvre
Position
Static
Turning error - false climb

Question 10

Leaks

Answer 10

Unpressurised - momentary rate of climb
Pressurised - descent untill pressure equaliles with cabin alt. Then gauge becomes a cabin VSI.

Question 11

Blockages

Answer 11

Alternate static - momentary rate of climb.
Static Blockage - Indicates level flight

Question 12

Rule of thumb for Qs

Answer 12

3 degree glideslope = 5% gradient.
5% gradient = 5 x groundspeed.