There are two ways of operating the gauge. One way is to use the full screen view, and the other is to use a small view in the main panel, so you may keep an eye on the flight instruments.
Full Screen View
1. Starting at cruise altitude, in the default 2D panel view, reset your gyro compass (press D key).
2. Turn on the Autopilot, setting the heading you desire into the Sperry.
3. Set "hold altitude" (ctrl+Z).
4. Look straight down (press "5" on numpad, hold and press shift key, release the "5", then release the shift key) and zoom out as desired, (pressing "-" key repeatedly).
5. Open driftmeter window in the top-down view (click view, instrument panel, select driftmeter) or use Alt+"v", then "i" then "d" keys. Drag the drift meter to the center of the screen if you need to view more of the landscape coming up.
6. Adjust parallel lines to see what the drift is.
7. Return to 2D panel, and adjust heading to correct for drift in the Sperry Autopilot (spacebar, then use mouse).
8. Return to straight down view, and confirm the drift angle matches the drift correction angle you set in. Since changing your heading will change the effects of the crosswind, you may need to make a second, minor adjustment.
9. Adjust as necessary.
Main Panel View
1. Starting at cruise altitude, in the default 2D panel view, reset your gyro compass (press D key).
2. Turn on the Autopilot, setting the heading you desire into the Sperry.
3. Set "hold altitude" (ctrl+Z).
4. Create a new view, looking top-down (Alt+V, then V, then d). If it opens covering something you want to keep an eye on, like the attitude gauge, drag the new view out of the way.
5. Open drift meter window (click view, instrument panel, select driftmeter) or use Alt+"v", then "i" then "d" keys. By using the mouse, and pointing to the outer ring, drag the drift meter over the new top-down view.
6. Adjust parallel lines to see what the drift is.
7. Return focus to 2D panel by clicking on it, and adjust heading to correct for drift in the Sperry Autopilot.
8.Confirm the drift angle matches the drift correction angle you set in. Since changing your heading will change the effects of the crosswind, you may need to make a second, minor adjustment.
9. Adjust as necessary.