Thanks to a few hundred hours of flight experience in my Lancair Evolution so far, I am really improving the flight model in X-Plane in the area of PT-6 engines, electrical, and pressurization systems! And, while in the systems code, I’ve improved a lot of other systems simulations as well, which is always fun.

So, here is the new stuff done for 11.00 so far in the flight and systems modeling area!

PT-6 engine modeling

Thanks to LOTS OF FLIGHT-test IN N844X, which has a PT6, I am getting that engine just right in X-Plane! I got the RECIP engine performance dialed in when flying recip engine airplanes like the Cirrus SR-22 and Columbia-400, and now I’m dialing in the TURBOPROP performance now that I’m flying a turboprop! Not only are the fuel flow and efficiency now correct.. but the engine just FEELS right.

But how does an engine FEEL right in a simulator? How does that make any sense?

Well, the PT-6 engine has a distinct feel to it to operate. That engine is all about having enough AIRFLOW moving through it to balance the FUEL FLOW to keep the temperatures under control. The turbine is slow to respond at low power settings, since not enough air is racing through to rapidly change the turbine speed. The turbine feels HEAVY to slow-moving air with little dynamic pressure, so the turbine is at first sluggish, slow to spin up! But as the speed picks up and the airflow with it, the turbine seems comparatively lighter compared to the airflow moving through it and responds much more quickly! So, adding fuel from a low power setting, temperatures spike as you add fuel at low turbine rpm, and cool as the turbine spins up.

The turbine sound is one sound and feel, the prop completely another since there is no connection between the turbine and prop! Only air between turbines connects the prop to the rest of the engine! So a PT-6 engine has a real feel and response in turbine RPM, torque, fuel flow and temperature over time as you adjust the throttle, prop, and idle lever at different altitudes and temperatures, always spinning up or down at varying speeds and temperatures as the fuel and air moving through it change.. it is really very Steam-Punk in its operation.

Technically described improvements

Much better engine ITT modeling for those turboprops, including response speeds on power, prop, or condition lever changes.

Better torque and fuel flow modeling as well.

The dynamic pressure through the power turbine across varying rpm ranges controls exchanging torque and rpm to get the same power, for accurate cruise performance as you dial back the prop rpm but hold constant fuel flow, and glide with the prop feathered or not as well.

The new turbine model includes, by the way, compressor stalls, which I have gone through first-hand! As well, I have done a lot of engine failure simulation tuning for hot start, ITT runway, compressor stalls and the like.

The turbine idle is now floating point like everything in a real PT-6. Move the red knob to move smoothly from low to idle, or hold it partway if you want to keep the engine temps JUST where you want, as you would in reality. Just remember to tweak those idle speeds in Plane-Maker now to get your idles just right!

For turbines, you will want to enter a higher high idle than low idle now… X-Plane does not do this for you any more, since you can now tune those fuel flows at idle as you like for yourself! At low idle, you need to be above 52% Ng for PT6 engines. At high idle, you want to be higher… the King Airs like to spin about 70% Ng to have enough speed to turn their air conditioner compressors!

The shop adjusts the idle stop points per-engine, per-aircraft, based on pilot or company desires. I like my idle speeds a bit low in 844X so the plane taxis almost like it was carefully designed, and not trying to race away by taxiing at 50 knots! So the low and high idle adjusts, set in engine window of PLANE-MAKER, should be set according to how your airplane is dialed in in reality.

For a king air you probably want 55% Ng for low idle, 70% for high idle, which work out to about:

  • HI idle: 1.70
  • LO idle: 1.00

in Plane-Maker. In other words, our low idle is just enough to run the engine at the lowest Ng recommend, and we bump that up by 70% at high idle to spin the generators and air conditioning compressors. This is fun to do, since you can get that idle Ng just right for YOUR PT-6 setup!

NOTE: THIS WAY OF ADJUSTING IDLE SPEED IS A HAIR DIFFERENT FROM VERSION 10. In version 10, the high idle was automatically boosted inside of X-Plane, but now it is not: You have to boost that high idle manually by entering a higher value for high idle in Plane-Maker. Also our whole turbine model is different now which also means the idle speeds need to be re-tweaked in your planes.

In my REAL airplane, when you turn ON electrical system stuff, it DRAGS DOWN the speed of the compressor. The compressor provides the cooling air that keeps the engine from destroying itself! This is a BIG DEAL for pt-6 airplanes! So as the generator load comes up, the turbine Ng does DOWN, and the ITT comes up… possibly enough to destroy the engine!

One day when it was really hot and I was taxiing with the air conditioning on and I taxied into a tailwind, the ITT started to go to REDLINE!!!!! I quickly turned off the air conditioning and the ITT quickly came down! I said “whew,” advanced from LO IDLE to HI IDLE to get enough compressor speed to support the electrical draw of the air conditioner, and THEN turned the AC back on!

So why was the idle speed set too low to handle the air conditioning on a hot South Carolina summer day? Because I had just had the idle adjusted to be lower… IN OREGON, WHERE IT IS COLD, AND THEY DON’T NEED AIR CONDITIONING! HAR!!!!!!!!!!

Now, at this moment in X-Plane, I am making all of this DEFAULT behavior. It’s SO EASY! The aircraft author ALREADY enters the electrical load in Plane-Maker for each system. The aircraft author ALREADY enters the generators and what engines they attach to. The aircraft author ALREADY enters the horsepower of the engine. So now, as I am coding right this moment, X-Plane looks at the amperage and voltage of each generator hooked to each engine.

What is amperage times voltage? POWER!

So we can MATHEMATICALLY FIND the power that is sucked from the compressor by the generator! And, yes, as you turn stuff on, the generator load will go up, the Ng will come down from the drag, and the ITT will go up! So it is all baked right into the model.. no user-mods needed.

As you increase electrical load on the airplane, that load will be passed to any turned-on generators which will drag down any engine attached to those generators, changing power output and temperatures accordingly! COOL!!!! All of this is done by the direct application of load to the engine. There is no ‘faking it’! If you have more electrical load on a smaller engine, then turning on your various electrical devices will have a greater impact on the engine, especially noticeable at idle!

While this is surely most noticeable on the PT-6, I have applied the affect to the pure jets and recip-engine airplanes as well, and also applied the drag on the engine from the pressurization system, when applicable. So we now have accessory drag on the engines. This is real, and very important.

Pressurization modeling

Also thanks to my experience in the Evolution N844X, which has has several pressurization failures in reality, in X-Plane I now have a whole new pressurization model!
In reality as well as now in X-Plane, you have to carry enough Ng (gas generator RPM) to hold up that pressure, and now we have fractional pressurization available to hold SOME pressure, but maybe not ALL pressure, as in the real airplane!

We look at the ratio of bleed air available and what part of the engine it comes from to see if we have adequate bleed air inflow to the cabin based on the current engine RPM, and local atmospheric pressure! The higher you are, the more power you better carry to keep cabin pressure, as in the real airplane! The cabin altitude will climb if you don’t.. and how much it climbs will depend on the air density outside the plane and the gas generator speed on a turbine! How much power you need to hold pressurization depends on the altitude and even baro pressure setting, since this is hooked to air pressure! Cool! Also a more efficient inlet pressure recovery and more speed gives more pressurization.. because the INLET pressurizes the air before handing it to the engine to pressurize further, as in reality! NICE!

After going over the Pilots Operating Handbook and my old notes from my Columbia-400, we have a new manifold pressure model! This seems to be better than the previous one!!

Electrical system modeling

The electrical system code is overhauled, with new models for generators and batteries, all connected though the various buses and cross-ties.

You can hop in a plane, take it up high, fail the engines, see the generator output sag based on the low engine RPM while gliding, watch the batteries in partial discharge due to low generator output, start the APU, turn on the APU generator, watch it power systems and charge the batteries, turn on too many systems and watch the APU get overloaded and have it’s amperage sag and the avionics flicker on and off, load-shed to get within
the APU amperage, turn off the batteries to avoid trying to charge them, and bring the airplane home on APU power only.

If yer good, that is.

Tire-force modeling.. WHEN THE PLANE IS NOT MOVING!!!

OK maybe my sense of humor is all screwed up after 2 weeks of straight coding but this one is just too funny:

For X-Plane 11 beta-3, I just solved a bug (pointed out by Vit Zenisek) that has actually been in X-Plane for 20 years… and only affects the motion of the airplane when it isn’t moving.

Got it?

Here’re the dynamics of the non-dynamic situation:

The tire force model in X-Plane is good enough to use in a driving racing simulator, as it actually gets right down to the vector along which the rubber is dragged across the pavement on the contact-patch of the tire. The dynamics are really quite good, especially in X-Plane 11 where I have taken tire-modeling updates from Stradale.

BUT, this physical model has fatal flaw: The model that simulates the detail right down to how the rubber interacts as it is being dragged across the pavements….only works WHEN THE RUBBER IS BEING DRAGGED ACROSS THE PAVEMENT! DUH! So when does it NOT work? WHEN YOU ARE STOPPED!!! HAR!!!

So, whenever an aircraft in X-Plane has been STOPPED, I simply ‘locked the airplane down’, bypassing the tire model altogether.

No motion? No flight model!

This SOUNDS fine, right?


During the run-up, the plane is indeed motionless, but the forces acting on the airplane, via the landing gear, are HUGELY important! As you add power, for example, the force opposing propeller thrust is COMING FROM THE TIRE CONTACT PATCH FAR BELOW THE PROPELLER! This aft force, far BELOW the prop, opposing the forward motion of the prop, creates a torque that LOWERS THE NOSE when power is applied with the brakes on!

You sure feel this on short-field take-offs, when you add power, holding the brakes, and the nose hunkers DOWN. Then, when you release the brakes, the nose POPS up as the nose-gear strut is unloaded and it is off you go! So, even though the airplane is NOT EVEN MOVING during the run-up or power application before brake-release, the forces on the landing gear and resulting aircraft dynamics are CRITICAL to making the X-Plane aircraft behave, and feel, like the real airplane!

SOOOO, how do we BUILD a tire model that is based on MOTION, but still works when the plane is STOPPED?

SIMPLE! We simulate a WELD!

When the plane is stopped and the tire forces are adequate to HOLD it there, we imagine that the tire contact patch is WELDED DOWN TO THE GROUND right at the center of the tire contact patch! The force on the airplane from the tires is a damped spring that opposes any displacement of the aircraft from that welded-down spot! Any (small) displacement from that world-point of the tire contact patch is due to the flexing of the tire sidewall, allowing the axle to move ever so slightly fore and aft as the tire flexes under the loads of the engine, wind, a sloped runway, or whatever else it is that is trying to move the airplane!

SO, when STOPPED, we weld the tire contact patch to the ground with a damped spring simulating the tire sidewall that holds you in place with, indeed, some FLEX! Then, as the brake are released OR the forces on the aircraft EXCEED the braking allowed by the tires… we switch over to the rolling or dragging dynamic tire models as needed! Cool!

The whole thing happens seamlessly, and the effect is really quite amazing. With the Cessna 172, for a short-field take-off, get all the way on the brakes and go to full power.. the nose starts to dive under the thrust! Then, get OFF the brakes and the nose POPS up and oscillates as the nose strut unloads, over-extends from the aircraft inertia, and oscillates a few times until the motion is damped out, as the airplane starts to accelerate down the runway!

It feels JUST like the real plane!

Control-effectiveness improvements

Control effectiveness at high AOA reduced according to wind tunnel results.. you lose it all by around 45 deg AOA… and a good solid 30% of it around 20 deg AOA. (This is in addition to losses due to dynamic pressure and local flight path no longer being aligned with the airplane, of course!) So, this makes the stalls a good bit scarier… that control deflection comes down for the recovery! And, if the stall is ICE-induced, where the ice lowers the stalling angle of attack, well, that plus reduced control effectiveness in the stall makes for some pretty scary stalls!

Based on information from a TBM-850 pilot that has done some stalls in his airplane when iced (by ACCIDENT!), ice is QUITE a different experience now. QUITE different.

A customer sent me a video of him stalling a TBM-850 with ice on its wings… it stalled WAY earlier than he planned. So now, rather than just adding weight and drag and reducing lift, which is what they teach you and what X-Plane used to do, we NOW lower the stall angle of attack as the ice builds as well.

This can lead you to think that everything is mostly ok with only a bit of ice, and then WHAM! That stall bites fast and hard, sooner than expected! A nasty stall at a much lower AOA than you expected! Then you have to recover without exceeding a much lower-than-expected AOA, with limited lift and extra weight and drag… which means you need to re-evaluate your new stall AOA from that first stall and not let yourself get up to that AOA level again to hit a SECONDARY stall! This is where the skill requirement shoots up through the roof.

So the ice is much more realistic, which results in it being more terrifying, by far. The new improvements in flight control realism at higher angles of attack then increase the challenge-factor further.

Rotor modelling

This is a modest upgrade to the rotor model for helos. We have some small internal re-organization, and significant tuning, to really nail the performance in:

  • Climb and cruise,
  • Effective Translational Lift,
  • Setting with power,
  • Settling WITHOUT power
  • mast-bumping, with mast-bumping limits in disc tilt set in the Plane-Maker window where you enter your cyclid deflections.

These tweaks really dial in the rotor performance to another level of refinement, which has been really fun to flight-test in the sim, for sure!

Other reciprocating engine improvements

We track the fuel in the cylinders or carb from the prime or simply running the fuel pump when the engine is not running! So the engine starts with a bang if you primed it enough or too much, or just barely rumbles to life if not. And, yes, in an emergency, you can fly the thing on the primer if the engine driven pump fails! That was not custom-coded. It works out because I coded the dynamics of the system!

Jet engine modeling

Low/high jet engine bypass types: GONE! Now we ONLY go off the bypass RATIO that you entered! This lets cool things like exhaust smokiness and engine mass for mass distribution all be floating point with bypass ratio for infinite variation, which is nice.

Hydraulic system modeling

Hydraulic systems have a bit more oomph, delivering at or near full actuation power at idle when engine-driven, as they should. So really dialing in these physical systems models here for 11.00.

Pitot-static modelling

Now we have more realism in the LAG of the airspeed indicator, which is really noticeable in a Columbia-400 doing a short-field take-off, and also the correct reactions when the pitot tube, static port, both, and neither are iced over to infinitely-variable fractions as well.

Other systems modeling

For roll with with elevator, yaw with rudder, aileron with pitch, the TRIMS now apply there as well! So if you use those controls, X-Plane now gives you the TRIM as well.

Updated electric motor dynamics as well! Now more accurate with battery depletion. I have a sense of how electric motors and re-generative braking work now from (wait for it) our family Tesla!

Now with cowl-flap drag! Set it in Plane-Maker! Drag scales with cowl flap deployment! Cool! I’m told it makes 15 knot difference on the Mooney Encore! Set the drag as need for your plane! Now cowl flaps can be a joystick axis as well.

Other flight-model improvements

There is now a BUTTON for boost, so in the engines page where you enter water injection or NOX or other boost, you gotta turn it on with the button to get it at max throttle.

The nosewheel steering model is a hair refined: We go from max to min nosewheel steering as the speed picks up as always, but if we have a tiller axis assigned, then we add the tiller and nosewheel steer, like real airliners. Cool!

Engine specific fuel consumption now scales with density not altitude, which is more accurate.

Propeller gyroscopic forces now fixed.. they were not quite right before but are now. Even though prop gyroscopic forces are fairly small in most cases, we have them mathematically perfect now!

Other features and refinements as requested

New view option: Lock to point. Lock onto any spot on the ground and you TRACK it! Nice for VFR pattern, etc.

Slung loads now rotate as they should on the end of the cable, so they look pretty decent now.

Radio altimeter has +/- 40 degree scan, so up to 40 deg of aircraft bank it is correct.. then it goes slant range… and of course useless at 90 deg bank or more.

More cockpit instruments and controls transmitted to external cockpits to really keep those external panels in sync with the master machine.

Unlimited weapons attachable to the aircraft in Plane-Maker, with that weapon action saved in replays as well, and a more efficient snapshot structure to recall the replays also.

Major new features

Pushback trucks and ground service vehicles! All with dynamic flight models and stuff and paths that they drive that are different for every airport so they never do the same thing twice… it’s all dynamic.


These are just tiny little bits of notes I took while coding. The real exciting thing here is the internal file formats: Everything is now designed, internally, to be object oriented, extensible and flexible, so we can add stuff in the future without breaking file formats.

59 comments on “Flight Model Improvements Done for X-Plane 11.00

  1. Hi Austin,

    Frame-rates are still very much hampered by cloud rendering (even on fast machines) so are there going to be any improvements in this area over the course of the X-Plane 11 run?



  2. First WOW.. What a post! Thank you for sharing both knowledge and update information.

    I filed a bug about the Throttel/Prop and I did not see any info about it here so my question is this as I am not a real pilot, so I do not know how it work.

    In Beechcraft B58 (which I do not think has the PT-6 engines – only King Air right?)
    After engines have starteted and running fine, they shuts down if “prop lever” is pulled back to idleposition?

    I was under the impression that this would only feather the prop, not kill the engine?
    Anway, if this is a bug, it will hopefully get fixed as per the filed bug report. If not please share your expertice on the subject as I am in any case eager to learn.

  3. Since you’re tuning the physics modelling, could you give a look at the overdone weathervane effects on ground, while taxiing or taking of even under the mildest x-wunds ?

    Apparently the problem lays more in the way weathervane stability is calculated in X-Plane, and since there is no parameter in plane maker to make fine adjustments it becomes difficult to control when aircraft is designed, unless irrealistic surfaces are added…

      1. this should be perfect in x-plane starting with beta 4 IF THE BRAKES ARE ON

        if the brakes are OFF, then yes it will weathervane since we switch away from the weld model with enough crosswind.. i may or may not be able to address it

        1. Austin,

          could you elaborate a bit more on the reason of the possible difficulty with modelling this in X-Plane – better/more plausible ground handling under cross winds when brakes OFF and aircraft starts to roll ?

        2. I can understand the weather vaning effect for castoring nose wheels. But for nose wheel steering attached to rudder pedals or the tiller, this should not happen if the steering commands the nose wheel to be centered.

          Now in real life I can understand if weathervaning applies force to the rudder pedals which has to be countered by the pilot in order to prevent displacement of the pedals. But I guess there aren’t many products out there that have force feedback built in, and the entire realm of force feedback would need to be uniquely tuned for each aircraft loaded.

          So in the absence of control input force feedback I would say that the behaviour of weathervaning effect should only consider the command position for the nosewheel steering, and the limits of lateral grip for the tyre on the ground, before the tyre grip cannot hold the sideways force anymore,

  4. Could a calendar ( Perpetual ) be added to X-Plane, allowing to set any date based on YYYY-MM-DD-HH:MM(:SS) ?

    With this we could finally have proper Moon and Sun ephemeris, including proper Moon phase, for any date and time and place on Earth.

      1. Unless you fly X-wing in Star Wars, yes it’s kind of beneficial.

        Good read for tonight :” North Star Over My Shoulder” by Robert N Buck

    1. Jose, the limiting factor on the moon code is not that you can’t set the year. The limiting factor is that the math that places the celestial bodies is buggy. We have a bug filed to fix it someday and some code laying around that solves the astrophysics, but as you can imagine this is lower priority than a lot of beta bugs and therefore isn’t a priority for 11.0.

      1. Another thing with these celestial bodies is their size. They’re absolutely ginormous in the sim. (Or were: I just checked in v11 and even the moon only showed its surrounding glow through a clear or dare I say stellar atmosphere, which couldn’t be attributed to overexposure. Has this been reported?) This artistic choice is right up there with the entire world turning vivid yellow when the sun is low in the sky. It detracts from the experience for me.

        When you do get to it, it would be cool to also have other planets in the sky. Doesn’t seem like too much of a stretch to add a few more orbital parameters and tints.

        Oh, and happy new year! I’d say happy solstice, but that was like 11 days ago by now. #accuracy

  5. Love the improvements around the generator and thermal systems. The locking system for view will be great to avoid having to refocus the view many times during critical turns when doing VFR flights, and the fuel flow improvements will have a nice positive impact on the game. Keep up the good work! Can’t wait to try the next beta.

  6. Interesting to hear about the changes to the ice modelling. I am curious if X-Plane is modelling tail ice as well (i.e. is it possible to get a tailplane stall in X-Plane before the wing stalls?)

    1. yes it can happen
      but there are no settings to guarantee the tail gets ice not the wing
      but if the cg is forward enough it MIGHT happen on an all-moving tail like a piper archer

      1. Cool, I’ll have to play around a little. Maybe a very forward CG and some pushovers/pull-ups. I’ll do my best!

  7. thank you very much

    I love X-Plane 11 – it feels great and can look so good, even now in first beta

  8. eta on next beta build as well as any idea when we will see the new g1000 and keyboard input for the gns 430/530?

        1. 11.0 means not in the initial release. Many things to tie together to make a stable version first. What’s more important, frame rate, bug fixes or a particular navigation system? Don’t be sad, be glad. 😉

    1. Why should the 430/530 have keyboard input? The real ones don’t, and they are just as much a pain to use as they are in the sim.
      In fact, the ones you are likely to run into in real life in banged-up rental Cessnas are so worn out, that some buttons not even trigger reliably, but you need to keep pressing with increasing intensity to finally get them to trigger.
      So X-Plane is already MUCH easier to use than a real one, because mouse clicks trigger reliably. Therefore I won’t add keyboard input to those units because it would not be “plausible”. Scroll wheel support on the rotaries is already much more comfortable than the real world counterpart.

  9. Dear Austin,
    the Vickers Viscount, Fokker 27, HS 748, HP Herald, Armstromg Whitworth Argosy, the Grumman Gulfstream I, NAMC YS-11,… – they stand for the brakthrough and success of turboprop power.
    Their engine was the Rolls-Royce Dart, single shaft and – in contrast to the PT-6 – with fixed connection between turbine and compressor.
    Is the new turboprop model able to simulate the Dart?

    Kind Regards

    1. yes it can sim this engine as a fixed turbine but the realism is not yet so good
      i gotta get some time in a plane with this type of engine to really dial it in

      1. In the C90 I noticed there’s still a noticeable variation in Fuel Flow with Prop RPM adjustments at constant altitude and throttle… FF shouldn’t vary in this way on a Pt-6, right ?

  10. Austin, I’m an X-plane addict since 2003 and I just wanted to say you truly rock. You and the team are the best! Thank you so much for developing X-plane!

  11. Hi Austin,

    I understand that X-Plane is “your” simulator and you are focusing on the things important to you.

    However, as a newcomer to X-Plane, let me share with you a concern of mine and of many people. The weather engine. For someone who enjoys flying airliners (like me), it’s disappointing. It’s impossible to see weather “creeping up” on the distance, and approaching a foggy airport, you can see the ground quite clearly, until you enter the fog and then you can’t see anything. I have this clearly depicted in the following video. Check at 8:20.


    There are freeware weather engines for the other sims that do the multiple metar/weather creeping up in the distance already, like this one //

    Maybe you could get this person onboard to work with you guys to improve X-Plane’s weather engine?

    I am not very happy with the fact that I have to spend around 70 bucks, more than the sim itself, to get a decent weather engine 🙁

    If you could eventually dedicate some time to look into this, that would be really great. All people who fly airliners would appreciate it deeply, I’m sure 🙂

    Many thanks.

    1. Might be a good idea to forget every experience you have from “other” simulator and focus on what is in front of you. X-Plane is soon in its 11 version and only recently we starting to get third party vendors dedicating their time to X-Plane. You should never compare any sim as per definition they are built differntly. Enjoy the the sim you choose to use.

    2. Bruno

      I don’t understand what your saying here. Xplane is a base simulator and you can add to it or not in much the same way as you can FSX p3d.

      I really am at a loss as to what your saying.

    3. Agree 100%. I come from P3d and imo xplane is too much a VFR sim with little attention for liners. Hope Austin recognize we exist, thx

    4. +1 for the weather engine. It is really basic in too many aspects.
      At least start to work on a model with good (not the one already implemented) thermal generation, because if you include a glider you should give the possibility to fly it in real conditions. Look at Condor Sim for example: very effective weather engine.

    5. Bruno has a point and his arguments should be seen as constructive criticism. If I’m not mistaken, Austin himself recently admitted that the weather engine needs an overhaul.

      Seriously, if an airport is fogged in, then it shouldn’t be visible from a higher flight level.

    6. Hi Bruno,

      I agree with you in saying that Xplane 11 still lacks of a decent weather engine (and about the fog issue I agree 1000%!!!), but I can say that the 70 euro to improve the weather are worth it!!! 🙂 Of course, XP11 needs an improvement in the weather, since flying is ALL about weather!!! I also agree when you say that this is Austin’s simulator, since the area they are concentrating are mostly the areas Austin is interested in! There are lots of IFR pilots out there that are asking a better weather representation from high altitudes… and now there is a 70 euro plugin that does it in an amazing way and it is improving, but what at least LR can do is to give a nice IFR night lighting experience!!! Lights from low level are amazing… but who flies an IFR flight from KJFK to KLAX at 5000ft? Austin, why you don’t try to get onto a 737 and go at 35000 feet at night in clear skies and look outside the cockpit and post here what you see??? For sure nothing!!! PURE BLACK! If you want to see some lights you have to look straight down! It is really unrealistic. Once I was flying from london to rome and I went to visit the cockpit (it was still possible at that time) and we were at 37000ft and over Turin. The sky was clear and I could see the lights of Florence, Bologna, and also start to see the lights of Rome at the very back of the horizon (I know cause the pilots told me what cities were). So, will it be possible to get some night textures for the cities so that we can hav e the lights extended to the horizon? At 30000ft who cares if they are 3d lights or not? Having all 2d lit textures of the terrain, will also improve a bit the performances cause you can get rid of the 3d lights underneath the aircraft that no-one can see outside the cockpit and that pops up as you get closer to them! Then while descending, at about 10.000ft a slow fade from the 2d lit textures to the amazing 3d lights 🙂 I think this will be really appreciated by the IFR fans! Thanks for the attention.

  12. Would also be nice to be able to adjust the ‘curves’ on toe brakes. Overly sensitive in GA aircraft right now (based on much real world experience).

  13. All of this sounds very good. Would like to see a gas pressure system as a hydraulic accumulator. This allows [a smaller] hydraulic pump to cycle On at a low pressure threshold, and Off at a high pressure threshold, with attendant effects on bleed air if using a pneumatic pump, or amp load if an electric one. In other words, it is similar to an electrical system, with separate systems (like buses) and cross-feed options.

  14. I ordered the demo of x-plane 1.0 out of the back of a magazine in like 1996. It was all untextured polygons. I can’t believe how far it’s come.

  15. Ben,

    This if Off Topic !

    What about the Mesh ? I think you had mentioned using the new Installer and re-downloading the Mesh but it has not worked, I tried California area by re-downloading it and it has water in a lot of places. So does the areas in British Columbia , hopefully other users could comment on that area.


      1. Well it’s all a huge download and @2MBPS it takes a lot of time , will try to find a few areas which are have water even with the tiles. and report them


  16. Austin,

    There is some funny thing i have noticed , i can pitch the 172 nose up even at 20-30kts on the ground , it’s a like prancing horse. Feels like the COG is in the tail section.

    As Jose above has commented , the weathervane effect.


    Hope the next updates gets some rendering optimization .


    1. starting with beta 3 the pitch effect of the skyhawk should be about right
      real skyhawks can ding the tails on the ground for sure
      this is simmed in x-plane certainly

      1. Hi Austin

        unfortunately I have to disagree to that. I am flying 150s and 172 regularly on grass strips. Soft field take off requires back pressure to relieve the nose wheel. I pull full aft for this and it takes a good ground roll to get the nose from ground just a bit.

        When I try the same procedure in X Plane immediately after applying full thrust the nose comes up all the way. That’s really unrealistic.

        Another issues I became aware of with beta3 is that C172 turns into the wind on ground. That’s really something which I have never experienced. Is this what everybody refers to as watervaning effect? It also makes the sims flight model questionable.

        Also the torque and maybe slipstream effect during ground roll feels exaggerated too. I got Saitek pedals and it turns heavily to the left when neutral. When taxiing at the usual 1000rpm this effect in reality is really almost not noticible. On take off roll and full thrust, of course you have to apply right rudder. However, I have not found a joystick setting yet that allows me a steady straight take of roll. There is always this enourmos left tendency and when I try to compensate the plane turns far to right.

        Is there any way to improve this?

  17. Hi,
    regarding push back/service vehicles, since many use WT or X-life to have realistic AI traffic, I think adding a flag to a parking position in apt.dat would solve lot of overlapping problems. Problem is that if I use a gate for an external traffic generated aircraft there is no way to tell Xplane not to use that very same gate.

    The only available solution is to deactivate native AI static and Ai traffic thus loosing completely the new dynamic features of ground vehicles at any airports. Not the best effect.

    With a simple On/Off flag we could tell Xplane to avoid placing static or AI at a given position reserving them for AI traffic generated by any traffic plugins.

    Even better would be the ability to call for ground services for a particular parking positions no matter how busy or empty, in this case we could let external AI aircrafts to get some life.

    Many thanks

  18. Wow- great to hear about the PT6 upgrades. My new home-built is using this and I am anxious to try it out in the sim.

    Has there been any updates to the way the “Stick force” output is calculate?
    I’ve found it a bit “off “in v10. I’m constructing a high-power force feed back yoke with hardware and software in the loop and find the Dataref for this is not the most realistic. I suppose its partly a function of standardizing for a “self centering” joystick, but I would assume your higher end simulators would be counting on this Dataref and would want it as accurate as possible. I can gather data from several other outputs and calculate my own control force … but it would be great if it was working well in the Sim.


  19. Austin,
    Sorry if this has been answered before.
    About the missing tile around Sydney.
    I do understand that it will be fixed.
    My question is if we must download the whole Australia and New Zealand mess again , or will that be incorporated in the next updates?

    Thank you.

  20. Great updates thus far. 11 has been fantastic!

    You mentioned working on a SR-22 performance model you had nearly nailed… just curious where that aircraft (with such lovely performance) may be found to install. I’ve been running Carenado’s… and it leave things to be desired.


  21. Hi, great changes! Would be awesome to see some more system triggered (not pre-set up/ time based) failures in other areas too(e.g. for piston engines…over-temp, over-rpm, too low engine temperature). But maybe thats there too already…need to check:) Limits have been there for a long time but never something happened, when exceeding….now i’m really not sure if it is there already and just didnt find the option:)

  22. This looks very promising. I (and several other people I know) are working on electric and hybrid planes. Any chance that you can incorporate both serial and parallel hybrids in the future. For GA in particular, there’s an explosion of new designs, and it’d be great to be a able to model them without fudges.

    Many thanks

  23. PS I should have added electric motors on the wheels too for taxiing, T/O acceleration, braking on landing and engine test. No needs for brakes in future aircraft!

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