Chapter 3: Flying in X-Plane Apollo

The Mission Segments
Each mission segment can be selected by entering the Settings menu (using the button highlighted in the image below), tapping the desired mission segment, and tapping the Go! button.


 * [[Image:Apollo_settings_highlighted.png]]

Separation
This is the segment of the mission that the application will enter when first starting up. All the user has to do is hit the SEPARATE button, and the path to touching down on the moon has begun!

Descent Burn
Following the separation from the command module is the descent burn, a 30 second firing of the engines that starts the lander toward the surface of the moon.

After beginning this portion of the mission, the rockets will automatically ignite for thirty seconds. At the end of that, the craft will be approximately 345,000 feet above the surface of the moon. Users can either choose to wait as the lander slowly makes its way down, or they can go back into the menu and select Powered Descent to skip over the wait. If users choose to wait through the unpowered portion of the descent, the sim will automatically enter the powered phase at about 45,000 feet.

Powered Descent
The objective of the powered descent phase is to slow from an orbital horizontal speed of about 3,600 miles per hour (relative to the surface of the moon) to a horizontal speed appropriate for landing—zero. This is achieved by pointing the lander's tail in the direction of the craft's motion and holding full power.

During this phase, be sure to keep the throttle slider all the way up. Use the white circle (found in the center of the screen) and the white dot to line the craft up with its direction of motion. For instance, when the white dot is below the circle, pitch the craft down so that the circle will move to meet the dot. When the dot is to the right of the circle, roll right to meet it.

Once the craft's orbital velocity has been burned off, it enters the vertical descent portion of the mission.

Vertical Descent
The vertical descent phase is where the craft descends the last 4,000 or so feet down to the surface of the moon. During this time, the lander's fore-aft and left-right velocities should be zero—that is, it should have no motion relative to the surface except its descent.

The goal here is to touch down very, very gently, with no ground speed at all and a level attitude for the lander. Use the tilt of the device to control pitch and roll, use the YAW slider to control motion left and right, and use the translational thrusters (labeled TRANS) to change left-right and fore-aft velocity. For instance, if, in the upper center of the screen, the simulator is indicating a positive fore-aft speed, drag the TRANS control down and hold it there a few seconds. If the sim is indicating a negative left-right speed, drag the TRANS control right, and so on.

In addition to all this, users must contend with the limited amount of fuel remaining. Use it wisely!

Upon touching down, the simulator will score the landing based on angular tilt, descent rate, ground speed, and the terrain hilliness.

Rove Around!
In this portion of the mission, the user is put behind the wheels of a lunar rover like the ones used for the last three Apollo missions. Tilt the iPhone or iPod forward to accelerate, back to brake, and left or right to steer.

See the Lunar Rover Wikipedia page for real video of the rover!

Launch
For the launch stage of the mission, all the user has to do is press the Launch button. This starts the craft on its way into orbit, eventually climbing 65 miles above the moon's surface.

Command Module Dock
When docking with the command module, the goal is to be perfectly aligned with the docking hatch with very little velocity when the lander touches the command module. This is achieved by closely monitoring:
 * a) the throttle control, to ensure that the craft is only barely moving forward when it docks,
 * b) the yaw control, to ensure that the lander is aligned with the command module,
 * c) the pitch and roll controls, to ensure that the lander is aligned properly when it docks, and
 * d) the translational thrusters, to ensure that the craft's hatch meets up with the command module's hatch.

Note that the translational thruster control (labeled TRANS) adds thrust to cause movement in the direction that it is dragged (for example, if it is dragged left, it will add thrust from the right side in order to push the craft left). Note also that the throttle control likely only needs little bursts of thrust—tap somewhere in the middle of the sliders range, and it will briefly power the thruster, then stop.

After docking, the simulator will give a score based on the angular tilt, position, closure rate, and lateral speed of the craft at the time of docking.