How do I speed up / compress time in th simulator?

[Captain Wolf]

I tried t, shift t, control t, alt t and none this seemd to have amy effect. I pressed l which made it later in the day, like day into night, but that is not what I wanted. I wanted to compress time to make a 3 hour flight into twenty minutes.

I was flying VFR (no auto pilot) from Seattle to Spokane in a Cessna which took a very long time. I was using 124th atc as a plug in, but then I tried to disable it, but that didn't help eitther. Thanks in advance.

[XPlanePhil]

To make your plane cover more ground in any given time, thereby speeding up your progress, press Alt+t. You'll see a small reminder on the screen that tells you you are flying with 2x, 4x, 8x or 16x ground speed.

[Apis]

nvm

[Captain Wolf]

Phil, thanks for the quick reply. I did notice the 16x in the top middle of the screeen. I think this is accelerating things the way I wanted. However, I'm not sure; shouldn't the chronometer move 16x faster with the plane? I don't think it does. I was using that as my indicator.

[Narxes081206]

You may be bound by the performance of your computer. If you're trying to move at 16x, that's a lot of rendering being done very quickly, thus the times may not exactly correlate with the 16x that the screen disiplays.

[XPlanePhil]

You guys are confusing two different time compression functions of the simulator. Can't blame you, since they both have the same goal, getting you home quicker, but work very different.


"Time speedup" is Ctrl+T and that is what Narxes081206 is talking about. It lets more sim time pass in less real time. That means it speeds up the internal clock of the simulator, and a second in the simulator is shorter than a real time second. That makes your clock run faster, and the simulation runs in compressed time. The downside of this is, as Narxes081206 points out, that you need the computing power to run all the stuff in less time. Remember X-Plane doesn't use lookup tables, but an aerodynamic model for the flight physics. The problem is we can not really run the physics at anything less than 1/20th of a second, or you get computational flutter effects. This is the underlying reason X-Plane never runs below 19fps, and if it does, it stretches the seconds until it is at 19fps in "sim time" (the opposite of time compression. Call it time stretching, if you will).
So, if you have enough resources to run X-Plane at 40fps, you can also run it at 2x time compression, meaning you are now running twice at many seconds in sim time. You still have 40fps in real time, but now only 20fps in sim time, and X-Plane will not allow you to go any faster. So you need more fps in the first place if you want more time compression.
It is also very hard to fly the plane by hand, since every joystick input causes the plane to change roll or pitch at 2x or 4x the speed, so you need to be twice as gentle with your joystick!

"Groundspeed compression" is Alt+T and it does not have the problem. Instead of stuffing more seconds into a second, it only covers more ground in a given time. That way, we can run the physics of the accelerations and velocities at normal speed, and only integrate the position at 2x, 4x, 8x or 16x speeds. Because the lower parts of the simulation still run in real time, we have no problems with computational flutter. This means the plane reacts to your joystick input as if you were in 1x time compression, your clock runs as if it were 1x time compression, you just cover more ground, because your position runs at 2x, 4x, 8x or 16x faster. This makes it even feasible to fly by hand at high compression rates.

If you simply want to "get there" faster, groundspeed compression (Alt+T) is probably what you want.
Ctrl+T instead gives you more of a "time-lapse" feel.

[Captain Wolf]

Thanks for the explanations

[Captain Wolf]

Originally posted by CringeKaptenen:

Another quick tip if you are doing a long haul, say trans-atlantic and want to speed up the process...

Do the normal Ctrl+T and then go to the exterior view, usually Shift+4 and then use the dot(.) or comma (,) keys to zoom out into space. Usually gets me from about x2,5 to atleast x5 or x6 the time-lapse. Using Shift+. or Shift+, increases the speed of the zooming. A pre-requiste is of course the use of an autopilot or you will likely crash very quickly. This certainly makes a long flight a lot quicker but still maintains a realistic fuel burn and time of day change. This method is very useful if you want to run good graphics rendering but still want to be able to use an effective time-lapse.

this did not work for me

[Apis]

Originally posted by XPlanePhil:

You guys are confusing two different time compression functions of the simulator. Can't blame you, since they both have the same goal, getting you home quicker, but work very different.


"Time speedup" is Ctrl+T and that is what Narxes081206 is talking about. It lets more sim time pass in less real time. That means it speeds up the internal clock of the simulator, and a second in the simulator is shorter than a real time second. That makes your clock run faster, and the simulation runs in compressed time. The downside of this is, as Narxes081206 points out, that you need the computing power to run all the stuff in less time. Remember X-Plane doesn't use lookup tables, but an aerodynamic model for the flight physics. The problem is we can not really run the physics at anything less than 1/20th of a second, or you get computational flutter effects. This is the underlying reason X-Plane never runs below 19fps, and if it does, it stretches the seconds until it is at 19fps in "sim time" (the opposite of time compression. Call it time stretching, if you will).
So, if you have enough resources to run X-Plane at 40fps, you can also run it at 2x time compression, meaning you are now running twice at many seconds in sim time. You still have 40fps in real time, but now only 20fps in sim time, and X-Plane will not allow you to go any faster. So you need more fps in the first place if you want more time compression.
It is also very hard to fly the plane by hand, since every joystick input causes the plane to change roll or pitch at 2x or 4x the speed, so you need to be twice as gentle with your joystick!

"Groundspeed compression" is Alt+T and it does not have the problem. Instead of stuffing more seconds into a second, it only covers more ground in a given time. That way, we can run the physics of the accelerations and velocities at normal speed, and only integrate the position at 2x, 4x, 8x or 16x speeds. Because the lower parts of the simulation still run in real time, we have no problems with computational flutter. This means the plane reacts to your joystick input as if you were in 1x time compression, your clock runs as if it were 1x time compression, you just cover more ground, because your position runs at 2x, 4x, 8x or 16x faster. This makes it even feasible to fly by hand at high compression rates.

If you simply want to "get there" faster, groundspeed compression (Alt+T) is probably what you want.
Ctrl+T instead gives you more of a "time-lapse" feel.

very good to know, thanks.

[Your Internet Dad™]

How do you turn off time and groundspeed compression once they're activated? Hitting the button combo again seems to only toggle through the various levels of compression.

[Captain Wolf]

keep hitting control t until the bar disappeaers in the top mid part of your screen. When it is gone, you are back to normal speed again.