Chapter 4: Flight
From X-Plane Wiki
Opening an Aircraft
When launching X-Plane for the first time, the default airplane will be loaded—in Version 9 this is the Cirrus Jet. After that, X-Plane will load the aircraft that was being used when the program last closed.
It’s a good idea to take your first flights in something simple, like the Cessna 172 SP. To open this aircraft:
- 1. Move your mouse to the top of the X-Plane window to cause the menu to appear.
- 2. Click Aircraft, then Open Aircraft, as in the screenshot below.
- 3. At the top of the window now open is a drop-down menu. It is currently displaying the name of the folder that the current aircraft is located in. Click the up/down symbol on the right side of the folder name, as seen in the following image.
- 4. Now a list of the folder hierarchy (the organization of the folders) opens from the drop-down menu. It starts with the main X-Plane folder and goes down to the folder that the current aircraft is in. For example, if the Cirrus Jet is open at the moment, the hierarchy shows:
- X-System folder
- General Aviation
- Cirrus Thejet
- Click on the line that says Aircraft, as in the following image.
- 5. The Aircraft folder opens. The folders here divide X-Plane’s aircraft into classes—for example, there are fighters, general aviation craft, gliders, helicopters, seaplanes, etc. Double click on General Aviation (shown in the following screenshot).
- 6. Now the navigation box in the lower left of the window shows the different aircraft classified as general aviation planes. Double click on the Cessna 172SP folder, as per the following image.
- 7. X-Plane aircraft files—which are what we need to click on to open an airplane—are denoted by an “.acf” extension. Double click on the Cessna_172.acf file (as seen in the following screenshot) to load the aircraft.
In a few moments the screen will go black. Shortly thereafter the cockpit of a new Cessna 172 Skyhawk will appear.
Choosing an Airport
X-Plane’s aircraft can be relocated to anywhere on Earth using the Select Global Airport window. This provides a listing of all the airports in the X-Plane database (currently more than 32,000), representing nearly every airport on the planet.
Note: If the aircraft is relocated to an area that does not have any scenery installed, it will end up on a runway which is hovering above the ocean down below. This is referred to as "water world" and it is covered in detail in Appendix L: Water_Everywhere.
To open the Select Global Airport screen:
- 1. Move the mouse to the top of the screen, causing the menu to appear.
- 2. Click Location, then click Select Global Airport, as in the screenshot below.
This screen is divided into three parts. In the top left (shown in the following image) is a listing of every airport name, arranged by city. Both this format and these names are the official standard for that local area (which, for US airports, is the FAA).
To the right of the list pane (shown in the screenshot below) is an overhead view of the currently selected airport’s layout.
The bottom half of the window (shown in the following image) displays rows of “quick start” buttons.
The buttons in the TAKEOFF column (on the far left) will transport the aircraft to the specified runway. To the right of these buttons are the FINAL APPROACH buttons, which will transport the aircraft to the specified distance away from the runway to the right of it. Finally, the RAMP START button will transport the aircraft to the specified ramp for takeoff.
To search the available airports, type either the city name or the airport ID into the white box below the list pane (labeled “Apt:”). For instance, in the image below, the user typed in “KLAX” to find Los Angeles International Airport. The same results could be obtained by typing “Los Angeles Intl,” or by simply typing “Los Angeles” and scrolling through the results.
Alternatively, use the up and down arrows on the keyboard to move through the full list. To travel to an airport, click on it once in the list pane to highlight it (causing a grey box to appear around it), then click the Go To This Airport button, as seen in the previous image.
Airport IDs Explained
Every airport on Earth has a unique identifier used to refer to the field in flight plans, instrument approach plates, and GPS navigators. In the United States, the airport identifiers are comprised of three characters, which can be letters only or a combination of letters and numbers. This sounds easy, but wait…
VORs, a type of navigation radio, also use the same identification system and, in some cases, the very same identifier. A VOR located on a field, for example, will have the same identifier as the field itself. To prevent confusion, the letter K is added before the identifier of the airport in the US if that identifier contains only letters. All VOR identifiers are letters only, so any airport identifier that has any numbers in the ID stays as is.
Here are some examples:
- 3CK stays as 3CK since it has a number in it.
- OJC (Johnson County Executive Airport) becomes KOJC for the airport because its identifier is letters only.
- The VOR on the field at Johnson County is also called just OJC with no “K” to denote that it's a VOR.
- AMW becomes KAMW for the airport. There is no VOR on this field so there is no other identifier for this airport.
For an interesting read on the history of the airport code naming conventions, check out Skygod’s page.
X-Plane’s weather simulation is highly configurable and remarkably realistic. To edit the weather settings, cause the menu to appear by moving the mouse to the top of the screen. Click Environment, then click Weather (as shown below).
Click the leftmost tab in this window (Atmosphere) to begin editing the weather.
Basic Cloud Configuration
In the upper left of the Atmosphere window (shown in the following screenshot), cloud types as well as the top and base levels for three different cloud layers can be set. The boxes designated MSL (found on the left side of this section of the window) are measured in feet above average sea level. The boxes designated AGL are measured in feet above average ground level.
The pane below the basic cloud configuration has a number of buttons, labeled cat-III, cat-II, cat-I, n-prec, and so on (seen in the following image). These are quick-set buttons, and pressing them will automatically set some general weather conditions.
- Cat-III sets the weather up for a Category-III ILS approach. These are extremely low instrument conditions, with basically zero ceiling and visibility.
- Cat-II sets the weather up for a Category-II ILS approach, with terribly poor ceiling and visibility.
- Cat-I sets the weather up for a Category-I ILS approach, with poor ceiling and visibility.
- N-prec sets the weather for a non-precision approach, with a 3 mile visibility and a 400 foot ceiling.
- MVFR sets the weather marginal VFR flying conditions, with about four miles of visibility and a 1,500 foot ceiling.
- VFR sets the weather to good visual flight rule conditions—-clear, sunny skies.
- CAVOK sets the weather to clear and visibility OK. Typically pilots refer to this as "CAVU”--Clear And Visibility Unlimited.
Below the quick-set buttons is a set of sliders. Click these and drag them to change their setting.
The visibility slider adjusts what its name suggests, measured in miles.
The precipitation slider sets the level of precipitation. Depending on the temperature around the airplane and in the clouds where it is formed, this will be in the form of rain, hail, or snow.
The thunderstorms slider adjusts the tendency for convective activity. The weather radar map in the lower-right of the window shows where the cells are forming. Flying into these cells results in heavy precipitation and extreme turbulence. The turbulence is great enough that in reality, airplanes can fly into thunderstorms in one piece and come out in many smaller pieces.
Taking helicopters into these icing and thunderstorm situations is pretty cool because their very high wing-loading on their rotor and the fact that the rotor is free teetering causes them to have a pretty smooth ride in turbulence. They are still not indestructible, though, and they are subject to icing on their blades just like an airplane.
The wind and turbulence slider automatically sets all the sliders in the center of the screen that control the wind and turbulence. Drag this slider down to the left and hold it there for a few seconds to set all of the wind and turbulence to zero for a smooth flight.
The turbulence in X-Plane is simulated very realistically. To see how incredible the turbulence in X-Plane is, drag the wind and turbulence slider up to the right and then close the Weather window (with either the Xs in the top or the Enter key). Now select an external view like Chase (by default bound to the ‘A’ key). Next, hit the ‘/’ key twice to see the wind vectors, then use the ‘+’ and ‘–’ keys to zoom in and out. For instance, in the following image, a Cessna 172 is getting tossed around the Austrian skies.
The green lines visible in the image above are the actual wind vectors acting on the airplane. Each of those vectors represents a wind speed and direction in the flow field around the pane, and that flow field will interact with each of the elements of each of the wings (and propellers!) of the plane. Additionally, the little green lines sprouting out of the bottom surface of the wings in the image above show the lift vector for each segment of the wing (in the example, these vectors are pushing the plane down).
Of course, when the aircraft is flying the lift vectors will be very prominent but even with the airplane just sitting stationary at the end of the runway, the wing can indeed be producing some measurable lift. The air may be blowing up on part of the left wing and down on part of the right wing, causing the craft to roll to the right. Or it might be pushing up on the wings and down on the tail, causing the craft to pitch up. Or, as it does in real life all the time, the air might be doing a combination of those at multiple points on the aircraft.
With the visual vectors turned on it becomes apparent just how much math is going on in the background within X-Plane. The flow field is continuous, variable, and covers the entire aircraft for any scenario that can be simulated, and all the different parts of each airfoil surface see different relative directions and speeds.
The bottom slider in the basic weather settings is the rate of change, which modifies how quickly the weather conditions are changing.
Temperature and Pressure
In the bottom left corner of the Weather window, the temperature and barometric pressure (air pressure) can be set, as seen in the following image. Both conditions will take effect at the nearest airport. Keep in mind that the “standard atmosphere” is 59˚F (15˚C) and 29.92 inches mercury (1013 millibars).
The middle column of this window controls three wind layers; the high altitude layer is shown in the following image.
Each layer has an altitude, wind speed, shear speed, shear direction, and turbulence associated with it. X-Plane will use the high, middle, and low altitude settings to interpolate between the layers. The circles to the right of each altitude setting change the direction from which the wind is coming. Click and drag near the edge of the circle and the wind will come from the direction that you let go of the mouse button (for instance, for wind moving from the south to the north, click the very bottom of the circle and release the mouse button there).
Enter the thermal tops, thermal coverage, and thermal climb rate in the upper-right of this window, shown in the following screenshot.
These controls are mainly used when flying gliders. In addition to thermals, X-Plane also runs air up and down the terrain as wind blows into mountains, simulating the effects that real glider pilots have to keep in mind and try to take advantage of. Try setting the wind at 30 knots or better at a right angle to a mountain range and running along the upwind side of the mountain range in a glider—-you should be able to stay aloft on the climbing air if you stay pretty low. Drift to the downwind side of the mountain, though, and an unstoppable descent is assured!
The runway conditions drop-down box is found on the right side of the Weather screen, directly beneath the thermals controls, as shown in the following image.
Conditions can be set to clean and dry, damp, or wet, and wet and damp conditions can be either patchy or uniform. At low enough temperatures, as in real life, a wet runway will become an icy one. This control is automatically modified when increasing the amount of precipitation.
Using Real Weather
Below the runway conditions controls is the Real Weather section. When the Periodically download Real-Weather box (seen in the following image) is checked, X-Plane will download actual weather conditions from the Internet (which are current within an hour) and apply that weather in the simulator. X-Plane will scan the thousands of airports that report weather and apply the weather from the nearest reporting airport to the simulation.
Of course, Internet access is required to use this option, but once the weather is downloaded (and automatically saved as a file called Metar.rwx) the same conditions can be used again (though they may be out of date) until X-Plane downloads an updated file. It is still nice to have the file, though, because it includes a global snapshot of the weather across the planet, giving weather that varies as the aircraft travels.
Just below the Download Real-Weather box is a check box labeled Periodically scan Real-Weather. This needs to be enabled for X-Plane to update the weather in the sim with the data from the Metar.rwx file. In other words, if the real weather is downloaded once per hour, but the user flies out of the area the craft started in without scanning the weather file, the weather experienced at the new airport may be different than what the real weather download contained.
Here's an example to clarify: A pilot is about to take off from Ames, Iowa (KAMW), and she downloads the real weather. This weather (clear sky and 15 mile visibility) is loaded onto her machine and she takes off. It takes 40 minutes to get to the Johnson County Executive Airport in Kansas City (KOJC), and as she approaches the area, she notes that X-Plane is still showing clear sky and 15 miles of visibility. She knows, however, from watching the news that Kansas City is actually experiencing low IFR conditions, with thunderstorms and significant turbulence. This indicates that X-Plane did not change the weather as she flew because she did not have the Periodically scan Real-Weather box checked.
Finally, when using the real weather downloads, the allow max visibility of control allows the user to (artificially) limit the visibility in order to keep the simulator’s frame rate at a desired level; for example, if a user knows from experience that a visibility over 10 miles causes the sim to slow to an unacceptable frame rate (say, 20 frames per second), he or she might allow a max visibility of 8 miles to be on the safe side.
Using the Keyboard/Keyboard Shortcuts
X-Plane has been designed to be both extremely flexible and easily usable. For this reason, most of the keys on the keyboard do something. X-Plane.org has created a guide to the default key assignments in X-Plane 9 that can be found here.
To see which keys are tied to which functions, simply go to the Joystick & Equipment screen’s Keys tab and look at the keys assigned to the various functions. Find this screen by moving the mouse to the top of the screen (bringing down the menu), clicking Settings, then clicking Joystick & Equipment, as seen in the following screenshot.
In the window that opens, click the Keys tab at the top.
There are two ways to change a key’s function here. The window has each key of the keyboard represented by a rectangular button (found on the far left of the screen), and it has that button’s function to the right of it. One way to program a key is to click one of the square buttons in the left-hand pane and select the function (found in the left-hand pane) that its key should control.
Functions are classified into a number of categories (operation, engines, ignition, etc.), found in the middle pane of this window. The functions themselves are found in the right pane of the window. Click on the radio button (that is, the small, circular button) beside the category you’re looking for, then click the radio button next to the function itself. For instance, in the following screenshot, the F1 key has been assigned to the throttle down function, found in the engines category.
Alternatively, click the Add New Key Assignment button found in the bottom center of the window (shown in the following image).
This will add a new gray button at the bottom of the left-hand pane, labeled <NONE>. Click this button and press the key you would like to program. Next, find the function you’re looking for in the right-hand pane of the window and select it.
Note: It is not necessary to try and remember all of the keyboard shortcuts. Instead, many of them are shown in the menus when flying. For example, while in flight, move the mouse to the top of the screen and click the View menu to see each view (listed on the left) and the keyboard shortcut it’s assigned to (found on the right within a set of brackets). For instance, in the screenshot below, the forward view has a “[w]” next to it, so it can be selected with the ‘w’ key.
Using the Mouse Instead of a Joystick
As alluded to in previous chapters, it is possible to fly with only a mouse for a flight control, though this is both cumbersome and unrealistic (since real airplanes all have either a stick or yoke). When flying with the mouse, keyboard shortcuts (found in the preceding section) become essential for controlling the engine(s), flaps, gears, radio frequencies, and views. Control of the plane via the mouse is available from most viewpoints.
Any time that the roll and pitch axes have not been assigned by the user in the Joystick & Equipment screen (see Chapter 3), X-Plane assumes that the mouse is the control device. In this case, a small white plus sign will show up on the screen, typically located near the center of it. Note that this may be difficult to see at times, as parts of the aircraft may blend in with it when using an external view.
If only the cross is visible and there is no white box around it, X-Plane is indicating that the pilot’s “hand” is not on the stick. This means that the mouse is free to move anywhere without impacting the flight controls. To grab the stick (and thus take control of the aircraft), click the left mouse button in the vicinity of the little white cross and a white box will appear around the cross. The mouse button down should not be held down, only clicked once to turn the box on (i.e., to grab the stick) and again to turn the box off (to release the stick). When the box is visible, the pilot’s hand is on the stick and any movements of the mouse within the box will position the flight controls accordingly.
Again, it is not necessary to hold down the mouse button down, only to move the mouse within the confines of the white box. The little cross signifies the center of the control range over which the control surfaces are deflected. Thus, moving the mouse directly below the cross will command some up elevator (causing the plane to climb) and not will not impose any roll commands (which should keep the aircraft from changing its bank). Likewise, keeping the mouse lined up exactly with the cross but deflecting it to the right a bit will cause the plane to bank to the right without altering its pitch.
Here is a summary of control with the mouse:
- Grab and let go of the stick by clicking the mouse button on or near the white plus sign. This will turn on and turn off the white box.
- Move the mouse right and left, up and down within the confines of the box to move the flight controls. For example, moving the mouse to the right edge of the box means that you are moving the aircraft control stick all the way to the right and the ailerons will be fully deflected at that point, causing the aircraft to bank right at its maximum rate.
- Let go of the stick (by clicking again within the white box) before you take the mouse down to the panel to change a control on the panel or else the flight controls will be deflected fully, causing the plane to gyrate out of control.
Controlling Instruments and Avionics with the Mouse
When using the forward cockpit view, the mouse can be used to control the instruments in the panel, just as the pilot’s hand would be used to manipulate the instruments, switches, and other controls.
To operate a button, just click and release. To operate a switch, do the same to change its position.
For example, to bring the landing gear down (on planes that are able to), click with the landing gear switch, as in following image.
Of course, this control will look different in different aircraft. Keep in mind that the ‘g’ key could also be used (see Keyboard Shortcuts) or a joystick button could be assigned to toggle the gear (see Chapter 3).
To turn knobs, move the mouse to the “plus” or “minus” side, whichever is necessary, and click to “move” the knob. Click repeatedly for greater movements. For instance, in the following screenshot, the pilot is turning the OBS knob in the Cessna 172.
To easily see the controls within the cockpit that the mouse can operate, enable the Show Mouse-Click Regions option found in the Aircraft menu. This will draw a thin yellow square around the areas of the instrument panel that can be manipulated with the mouse.
Note on Radio Tuning
Avionics in most airplanes utilize twin concentric knobs that allow the pilot to tune the radio. For example, there will typically be a large knob on the surface of the radio, with a smaller knob sticking out from the large one. The large knob controls the integer (“counting number”) portion of the frequency and the smaller knob controls the decimal portion.
For example, imagine that the COM1 radio (the communications radio number 1) needed to be tuned to 128.00 MHz. In a real aircraft, the pilot would turn the big, lower knob until 128 was visible in the window, then turn the small, upper knob until 00 was visible.
X-Plane is set up the same way. When hovering the mouse in the vicinity of one of the radio tuning knobs, two counter-clockwise arrows will appear on the left of the knob and two clockwise arrows on the right. The arrows closest to the knob are physically smaller than those on the outside—these adjust the decimal. The outside arrows are larger and adjust the integer.
For instance, in the following image, the integer portion of the NAV 1 radio’s frequency is being turned up using the outer knob.
Conversely, in the following image, the decimal portion of the NAV 1 radio’s frequency is being turned down with the inner knob.
Artificial Intelligence (AI) Demo Flight
X-Plane has the capability to fly an aircraft using artificial intelligence (AI). The AI system can both take the aircraft off and fly it around.
To enable the AI’s control of the craft, move the mouse up to the top of the screen to bring down the menu bar. Click About, then select A.I. Flies Your Aircraft, as seen in the following screenshot.
With the AI controlling the airplane, the user is free to experiment with the different views and also to practice raising and lowering the aircraft's landing gear, flaps, and so on. Furthermore, this is an excellent way to practice tuning radios.
When first flying (both in X-Plane and the real world), it’s a good idea to use a relatively simple aircraft. The Cessna 172 is an excellent choice in this regard, a fact attested to by the millions of real world pilots trained in this model. For instructions on opening an aircraft, see Section I of this chapter.
To take off, the airplane must first be located at the end of a runway. X-Plane relocates the craft here whenever the program opens, an aircraft is loaded, or the location is changed. To take off in the Cessna 172, slowly advance the throttle, then release the brakes when the throttle reaches its halfway point. Continue to advance the throttle and be ready to feed in some right yaw (using the right rudder or the twist on the joystick, if applicable) as the airplane accelerates. The tendency to turn to the left is normal in single engine aircraft due to the turn of the propeller.
Don't worry if it takes a few tries to learn how to keep the aircraft on the runway—a Cessna can take off in the grass just fine. If the airplane turns off the runway as it’s accelerating, just keep on going. Normally, the pilot will rotate (that is, apply some back elevator by pulling back on the yoke or stick) at about 60 knots in the Cessna 172. Once the aircraft leaves the ground, feed in a bit of forward stick to momentarily level off and allow the airplane to build speed. Once the craft reaches 80 knots or so, again pull back gently on the stick and resume climbing. Building airspeed before climbing this way will help to keep the plane from stalling.
Note that if a crash occurs that damages the airplane too badly, X-Plane will automatically open a new airplane and place it at end of the nearest runway (which in some cases may be a grass strip). If the impact is only hard enough to damage the airplane without necessarily killing the occupants, the aircraft will just sit there and smoke. If this happens, the user will need to move the mouse to the top of the screen, click File, then click Open Aircraft to get things fixed. If only it were so easy in the real world!