The author of this text is unknown. I grabbed this excerpt from the internet, and intend to modify it specifically to our needs. This is a start, however.
First, know that there are two basic turn rates. The Standard Rate Turn (SRT, sometimes known as a Rate 1 turn) means you are turning at a rate of 3 degrees per second. That means a 360-degree turn will take 2 minutes. See the images below for examples of these turns
The Half Standard Rate Turn (HSRT, sometimes known as a Rate 2 turn) is just that - one half the rate of the SRT. That means at 1 1/2 degrees per second rate of turn, and it will take you 4 minutes to turn 360-degrees.
Both the HSRT and the SRT times, assume you are flying a coordinated turn. That is, the "ball" is centered during the turn.
Turn and Slip Indicator images showing (from left to right), T&S needle centered, no turn; Half Standard Rate Turn to the left, Standard Rate Turn to the left. Note that the Ball is centered in all three examples.
Here is a table to help you compute your Timed Turns. Degrees to Turn SRT - Time HSRT -Time 360 2 minutes 4 minutes 180 1 minute 2 minutes 90 30 seconds 1 minute 30 10 seconds 20 seconds 15 5 seconds 10 seconds
Typically, use a SRT for turns of more than 30 degrees and use the HSRT for turns of 30 degrees and less.
You could make this chart as large as you like covering more and more different degrees to turn. In fact, you could make it 360 lines long and cover the gamut, but how many reams of paper would that take. If you find yourself in a Partial Panel situation, have the Copilot (the Pause key) jot down the basics. The five I listed above should do the trick. Now you have to turn 120 degrees, how much time would that take? Answer: 90-degree turn (30 seconds) plus 30-degree turn (10 seconds) and 40 seconds should do. How about 80 degrees? Well that's a bit shy of 90 degrees, so my guess would be around 26 or 27 seconds. You can't fly so accurately that a second or two will throw you way off course. In actual practice, you are going to find that you turn, roll out, check the MC, and turn again to get closer to the desired heading.
To make smaller turns, maintaining final approach heading, etc., count the seconds to yourself. Say you are 5 degrees left of heading. It will take you part of a second to roll into the bank and another part of a second to roll out of the bank, maybe one second total. How much is 5 degrees at 1 1/2 degrees per second. The math gives me a headache :-) It's probably about 3 seconds, so roll into the bank, count: one, one-thousand -- two, one-thousand -- three, one thousand and roll out. Check the MC to see how you did. Turn further or turn back if you missed the heading.
I've flown No-Gyro approaches with a ground controller using radar guidance. Once near final approach heading, the controller usually gave a roll in command -- "Start turn, now" and a roll out command -- "Stop turn, now." It's amazing how close to the runway they can put you.