Chapter 18B - Inertial Reference Systems

Question 1

RLG measures ?

Answer 1

Rotation around the sensitive axis

Question 2

What are some advantages of IRS over INS?

Answer 2

• Reduced alignment times, with little or no spin up time
• Improved accuracy – EASA 0.5 NM/hr
• Insensitive to gravitational forces
• Mechanically simple – better reliability
• Smaller and lighter
• Lower power consumption
• Longer MTBF – Mean Time Between Failures

Question 3

IRS is also known as a ?

Answer 3

Strap down system

Question 4

What’s the purpose of a dither motor?

Answer 4

Prevent laser lock

Question 5

For the alignment, the AC should be?

Answer 5

Stationary

Question 6

What is the overall alignment sequence in an IRS?

Answer 6

Overall alignment sequence…

1. Automatic test of the battery
2. Establish local vertical
3. Establish True North
4. Establish correct Latitude

The time for a normal alignment of a strap down inertial system is about 10 minutes.

Question 7

ATT gives you?

Answer 7

Attitude reference

Question 8

With an IRS, Two repeated long inputs different from the stored value?

Answer 8

The system accepts the new value.

Question 9

With an IRS, Two repeated latitude inputs different from the calculated value?

Answer 9

The system does not complete alignment.