Experts

How X-Plane Works?

X-Plane works by reading in the geometric shape of any aircraft and then figuring out how that aircraft will fly. It does this by an engineering process called “blade element theory”, which involves breaking the aircraft down into many small elements and then finding the forces on each little element many times per second. These forces are then converted into accelerations, which are then integrated to velocities and positions… Of course, all of this technical theory is completely transparent to the end user… you just fly! It’s fun!

X-Plane goes through the following steps to propagate the flight:

1. Element Break-Down

Done only once during initialization, X-Plane breaks the wing(s), horizontal stabilizer, vertical stabilizer(s), and propeller(s) (if equipped) down into a finite number of elements. The number of elements is decided by the user in Plane-Maker. Ten elements per side per wing or stabilizer is the maximum, and studies have shown that this provides roll rates and accelerations that are very close to the values that would be found with a much larger number of elements.

2. Velocity Determination

This is done twice per cycle. The aircraft linear and angular velocities, along with the longitudinal, lateral, and vertical arms of each element are considered to find the velocity vector of each element. Downwash, propwash, and induced angle of attack from lift-augmentation devices are all considered when finding the velocity vector of each element.

Propwash is found by looking at the area of each propeller disk, and the thrust of each propeller. Using local air density, X-Plane determines the propwash required for momentum to be conserved.

Downwash is found by looking at the aspect ratio, taper ratio, and sweep of the wing, and the horizontal and vertical distance of the “washed surface” (normally the horizontal stabilizer) from the “washing surface” (normally the wing), and then going to an empirical look-up table to get the degrees of downwash generated per coefficient of lift.

3. Coefficient Determination

The airfoil data entered in Part-Maker is 2-dimensional, so X-Plane applies finite wing lift-slope reduction, finite-wing CLmax reduction, finite-wing induced drag, and finite-wing moment reduction appropriate to the aspect ratio, taper ratio, and sweep of the wing, horizontal stabilizer, vertical stabilizer, or propeller blade in question. Compressible flow effects are considered using Prandtl-Glauert, but transonic effects are not simulated other than an empirical mach-divergent drag increase. In supersonic flight, the airfoil is considered to be a diamond shape with the appropriate thickness ratio; pressures behind the shock waves are found on each of the plates in the diamond-shaped airfoil and summed to give the total pressures on the foil element.

4. Force Build-Up

Using the coefficients just determined in step 3, areas determined during step 1, and dynamic pressures (determined separately for each element based on aircraft speed, altitude, temperature, propwash and wing sweep), the forces are found and summed for the entire aircraft. Forces are then divided by the aircraft mass for linear accelerations, and moments of inertia for angular accelerations.

5. Get Back to Work

The process is repeated from step 2, and the whole thing is run over again at least 15 times per second. Aren’t computers great?

Advantages of Blade Element Simulation

This method of computing the forces on the airplane is much more detailed, flexible, and advanced than the flight model that is used by most other flight simulators. Most other simulators use something called “stability derivatives” to compute how an airplane flies. This technique involves simply forcing the nose to return to a centered position along the flight path with a certain acceleration for each degree of offset from straight-ahead flight of the airplane—for every degree of angle of attack the nose is raised, the nose should return to center with a certain acceleration. This is a perfectly nice rule of thumb, but is far too simplistic to use across the flight envelope of the airplane.

Stability derivatives will not normally take into proper account the asymmetric affects of engine failures, the chaotic effects of turbulence, stalls, and spins, and the myriad of dynamic effects that are generated by the props of planes and the rotors of helicopters, such as spiraling slipstream, P-factor, and translational lift. As well, these simplifications can not easily consider such effects as transonic drag rise and compressibility which effect different parts of the airplane in different ways at different speeds, angles of attack, sideslips, and rotation rates.

Stability derivatives will typically say,

Okay, we are flying at Mach 0.8, so we add 5% to our drag due to compressibility,

in a situation where blade element theory will say,

Okay, we are flying at Mach 0.8, but the wings are swept at 45 degrees, and the plane is in a 5 degree right side-slip, so the effective sweep on the left wing is only 40 degrees, but the effective sweep on the right wing is 50 degrees, and the plane is rotating at 10 degrees per second to the right, so the advancing wing has an extra 10 knots of speed at the wingtip due to this rotation, but the retreating wingtip has 10 knots less speed due to this rotation, and the roll rate is 30 degrees per second to the right, which increases the angle of attack from nothing at the center of the plane to 2 degrees at the right wingtip and negative 2 degrees at the left wingtip, and the plane is pitching up at 10 degrees per second, which adds 1.5 degrees of angle of attack to the tail and takes away 0.1 degrees angle of attack on the main wing because it is in front of the center of gravity, and the changes in angle of attack cause increase in induced drag on the horizontal stab reduction in induced drag on the forward wing.

Furthermore, the above is only a gross approximation—the simulator does this for each piece of the wing, horizontal stabilizer, vertical stabilizer, and propeller blade to really build a model of what the airplane is doing.

In other words, the commonly-used “stability derivatives” are over-simplifications of how an airplane flies; in contrast, blade element theory figures out the forces on each little bit of the airplane to model the way it would fly in the real world. Blade element theory is much more robust, and it can give greater accuracy in a much wider variety of flight conditions. Furthermore, stability derivatives cannot predict how an airplane will fly. The aircraft model’s creator has to figure out how the plane will fly and then use the stability derivative to mindlessly spit that performance back out. Only blade element theory can accurately predict what an airplane of a given geometry will do; Microsoft Flight Simulator cannot do this. Instead, whoever designed the airplane has to tell the simulator how the airplane should fly, and the simulator then spits that information back to the user—nobody actually learns anything. With blade element theory, though, as used in X-Plane, you can enter the shape of an airplane and let X-Plane figure out how a plane of that shape, weight, power would fly!

Get the best hardware for the best game!

X-Plane works with a countless number of joysticks and hardware. However, if you would like help selecting the perfect hardware guaranteed to work with X-Plane, here are our suggestions.

Digital Edge sells joysticks, yokes, throttles, and pedals by CH Products, all of which have been selected for their high quality and known compatibility with X-Plane.

Mac computers

Austin Meyer, the author of X-Plane, does all of his development work for X-Plane on Macs, and he recommends them. The latest iMacs and Mac Pros from Apple run X-Plane well, though they will not be able to “max out” X-Plane 10 (there’s not a personal computer on the planet to do that yet!).

Windows computers and joysticks

Digital Edge is a company run by Laminar Research employees that sells Windows computers and accessories that are guaranteed to work with X-Plane out of the box. If you are not sure which joysticks to get, which computer to buy, and so on, we recommend going to Digital Edge for that hardware. Everything you get there will have been selected by Laminar Research employees to work perfectly with X-Plane.

Data Input and Output
The Data Input & Output screen is used to view or save data about what X-Plane is doing, as well as to interface different copies of X-Plane running on different computers together.

This window can be used to output the simulator’s frame rate (a very common choice) or any of hundreds of other parameters as well.

This is by far one of the most powerful tools in X-Plane. It can be used to diagnose a variety of problems because it allows the user to see what X-Plane is “thinking” and determine why it may be doing something unexpected. This screen can also output a host of engineering conditions.

From Left to Right:
1st box: Internet via UDP
2nd box: data.txt
3rd box: Graphical display in Data see Tab
4th box: Cockpit during flight

To understand why the Data Input & Output screen is so powerful, imagine for a moment that your “BRAKE” light is illuminated on the instrument panel, but you don't know why. You've tried to turn it off by clicking on it with the mouse and you've also tried to use the 'b' key (for 2/3 braking force) and the 'v' key (for maximum braking effort), but it is still illuminated. You have previously set up a set of rudder pedals to control the rudder and brakes but cannot find anything wrong with the way they were set up, and you are not pressing the brake pedals.

To find out what is causing X-Plane to engage the brakes, you could try checking the rightmost box on line 14 (labeled gear/brakes) in the Data Set tab. After closing the Data Input & Output window, note that a line of green text appears in the upper left corner of the screen. There are four data fields in it, showing a value of between 0 and 1 for:

the landing gear status (1 is gear down, 0 is gear up)
the wheel brakes (on both main gear evenly), and
the left and right brakes (if you're using a set of pedals or have programmed the brakes to be activated by some other control)
For this example, suppose that the right brake was showing a value of 1.0. This indicates that that brake is locked. You remember that you had mapped individual brake controls to your rudder pedals. Perhaps the problem is there. Apparently, X-Plane thinks that you are commanding the right brake to be on. There may be a problem with the calibration of your equipment, so you go to the Settings menu and open the Joystick & Equipment page. There, in order to calibrate the joystick hardware, you move all of your control inputs through their full range of motion. This teaches X-Plane what kind of data the rudder pedals are sending out for the full range of brake applications. For the purposes of the example, you go back to the sim and the problem is solved.

X-Plane Wiki

Fly in space, Fly on Mars!

Read the warning on the picture above- This warning will appear when you open a Martian terrain.

Fly an Earth plane on Mars. It would NOT fly properly due to the difference to air density and gravity difference

It is fortunate to have these functionalities here, together with the sim as other sims like Microsoft Flight Simulator takes missions like the special situations for payware.

Carrier Ops and racing situations requires FSX Acceleration

X-15 missions are payware missions, but the Orbiter mission can be Downloaded For FSX as 3rd Party app

BUT... I dont know why Mars flight was taken out from X-Plane 10

In Mars, the layer of air is 1% of Earth's thick air and the gravity is only 1/3 of Earth's.
Try to fly a Mars Plane on Earth. X-Plane 9/Aircraft/Mars Planes/MarsJet/MarsJet.acf

Notice that flying below 80,000ft will feel so iffy due to the difference of air density and gravity of two different planets

See the following links for more info

X-Plane Wiki
XSquawkBox.net- Scenery dev page
X-Plane Wiki- Scenery Development
X-Plane SDK- Plugin Admin
X-Plane Airport and Nav Data


Simulating Combat in X-Plane

Picture: F-16C Firing an AIM-9 Sidewinder , Close Range Assault

" Magic to Warwolf Leader. Bogies are confirmed hostile on a direct course to Miami. You are clear to engage and destroy" -Nightmare, Mission 1, ACAH

"Warwolf flight, Engage Fighters!" -Siege, Mission 9, ACAH

-Ace Combat Assault Horizon

Get Ace Combat in 3 easy steps!

1: Go to plane maker, arm the aircraft under default weapons tab, or go and find DLC fighters (CFA-44) and play with it.
2: Go to X-Plane, Aircraft> Weight and Fuel, Weapons tab, and arm the weapons.
3: Configure Joystick/ Equipment Settings>Joystick and equipment, set trigger to "Fire any armed" or spacebar by default
4: Follow steps below to add target aircrafts and kick their asses!


In App, go to Aircraft; Aircraft and Situations tab

Select the number of Aircraft and put yourself onto a team. Any plane on a team will pursue another plane which is an opposing team or no team at all.A Plane which has no team will wander around the general scenery area.If the plane is a fighter he may even open fire at you! Any plane which is hit by any ordinance will have its engines damaged and smoke. Of course you can fire missiles back at enemy fighters! Note that X-Plane is NOT a combat simulator so missile hits will just smoke out the other planes engines, not explode. This is to enjoy COMPETITION, not to simulate assault. Note that the [ and] keys select targets and some fighters like the Japanese Anime have weapon consoles that you click to fire the selected weapon

TRY!!!

Set 10 Aircraft that have the same performance of your plane and set them on a different team of yours, meaning 10 vs 1. Set your plane on medium speed and altitude on Autopilot and give them 10 minutes to catch up with your plane. Then add some wind and turbulence. Then Switch to Circle view (Shift-\) and turn on the force vectors (/)

Set 1 plane which has NO TEAM AT ALL. Then select all of the aircraft including yours on one team. Within time the rest of the team will follow the plane with no team as he wander around the area!

Choose fighters for each different teams and watch the sparks fly! With fighters, Choose AI flies your Aircraft to get the combat autopilot energized!

For more info about combat strategies see Dogfight videos


Mid Air Refuelling

Approaching the tanker in the default F-22, Tanker Speed 350 knots, Heading 010, Flight Level 100

You will now try to fly the probe of your airplane to within a few feet of the refueller craft's probe and hold it there

You will receive fuel while doing this

You should try it out in a Fighter like the default F4 Phantom, or any plane designed which have a refuelling probe in Plane Maker

See In-App - File>Load Situation>Air Refuel Boom to try out