BreezyPointDeparture

Aircraft Stress + Icing in P3Dv4

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Hey Everybody,

Hope y'all in the US had a nice Thanksgiving!

I was flying JFK-DEN - I don't have the METAR but I set up some custom weather which was very rough (at DEN). After flying through about 80 miles of weather, at 20 miles from DEN the sim stopped stating "Crash - Aircraft Over-stressed."

I am curious about the following points and looking for insight:

  1. Does PMDG internally record stress - as in, does aircraft stress from weather, or any sort of movement, negatively impact the aircraft which can cause damage/faults (that would show up in the FMC Failure section)?
  2. Alternatively, if I uncheck "Aircraft Stress Causes Crash" in the P3D settings - and I continue flying with the plane bouncing everywhere, does this make a difference to the internal settings of PMDG - and how the FMC records failures/faults? By unchecking - am I hindering the realism of the PMDG settings (not reality, where I know the plane would break apart anyway)?
  3. What do you guys do? Do you guys like to fly through hell and keep the setting un-checked?
  4. Icing - is this simulated in P3D and 747QOTSII? I tried to leave the plane on the tarmac once for 2 hours just sitting there, and then started up the engines and took off just fine without icing being turned on - curious if this is simulated or if I need to update a setting?

Many thanks for y'alls insights!

Best,
Max 

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Full names here please Max.

i always uncheck aircraft damage.  The simulator has very unrealistic crash detection, and there is no structural failure feature in the FDX so it pretty much just acts like a game.

I'm not sure about icing effects, various products have some icing caused degradation of performance but I'm unsure about the B744.

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I fly  with AS and always avoid the cells and turbulence areas when I can detect then on the weather radar and avoid as well the cumulonimbus when flying daylight.

It's part of trying to reproduce real flight as real as it gets. I was surprised sometimes to see some curves in my flight path very similar to the ones of the real flights on flightradar24 when avoiding these areas.

I also prepare my flight plans taking into account the sigmets and sigwx.

Even if it is just simulation, we have access to real data and and accurate weather tools. So I believe that if I can afford buying theses tools, then with the high level of realism that PMDG brings to us in their addons, they deserve to be flown accordingly.

Wouldn't be interesting to me to just takeoff and climb and leave then the aircraft following the route blindly until the descent.

As for the icing, I don't know either if there is any icing effect on PMDG's, it doesn't do any harm to follow the cold weather procedures anyway which I try to do as much as I can.

The thing I miss is the icing visuals which is a good indication to when turn the wing anti-ice on like there was on the JS41.

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22 hours ago, downscc said:

Full names here please Max.

i always uncheck aircraft damage.  The simulator has very unrealistic crash detection, and there is no structural failure feature in the FDX so it pretty much just acts like a game.

I'm not sure about icing effects, various products have some icing caused degradation of performance but I'm unsure about the B744.

Opps! I always forget my last name!!

 

Thanks a lot for the info - would love to hear if other people experience real icing. 

 

Max Castro

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22 hours ago, Budbud said:

I fly  with AS and always avoid the cells and turbulence areas when I can detect then on the weather radar and avoid as well the cumulonimbus when flying daylight.

It's part of trying to reproduce real flight as real as it gets. I was surprised sometimes to see some curves in my flight path very similar to the ones of the real flights on flightradar24 when avoiding these areas.

I also prepare my flight plans taking into account the sigmets and sigwx.

Even if it is just simulation, we have access to real data and and accurate weather tools. So I believe that if I can afford buying theses tools, then with the high level of realism that PMDG brings to us in their addons, they deserve to be flown accordingly.

Wouldn't be interesting to me to just takeoff and climb and leave then the aircraft following the route blindly until the descent.

As for the icing, I don't know either if there is any icing effect on PMDG's, it doesn't do any harm to follow the cold weather procedures anyway which I try to do as much as I can.

The thing I miss is the icing visuals which is a good indication to when turn the wing anti-ice on like there was on the JS41.

Totally hear you on the realism - thanks for sharing. 

Max Castro

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Max,

Icing effects on lift and the pitot static system are the default effects embedded in the simulator platform, which is to say they are rudimentary at best.  The FSX/P3D icing impact on pitot systems is mostly accurate for a C172, but not for a 747.  The 747 has a very well redundant pitot static system that is largely independent and you **SHOULD** never expect to see a catastrophic icing related failure in the normal service life of the airplane.  The effect of icing on the airframe is done by FSX/P3D adding the weight of the ice to the airplane, but doesn't have any airflow/lift penalty, which is the primary negative interaction of airframe icing in the real world...

Again though, in a modern turbojet airliner, ice is something you think about primarily in terms of avoiding setting up a condition in which you get ice adhering to the back side of the blades on the N1 stage, or on the wings/fuselage top surfaces prior to takeoff.  Beyond that it is handled without drama by the airplane's systems.

 

Now- turbulence...  oh boy.  This is one of my big pet peeves in the FSX/P3D realm.  I have written on this extensively in the general forum- and you can search up those writings if you'd like to learn more in detail- but suffice to say the simulation of turbulence in FSX/P3D/XPL leaves quite a bit to be desired.  Ignore the claims of "accurate turbulence" from any of the developers...  Nobody has a model that works well at all altitudes for all airplane types.  Right now- most models are "mostly accurate" for a small, GA airplane like a C172- but that is pretty much where it stops.

Turbulence in FSX/P3D is imparted by rapidly cycling the wind speed/direction which- reasonably approximates what happens in the real world, I suppose.  Unfortunately- the cycling tends to create instantaneous G loads on the airplane of anywhere from 5-15G.. which would make modern aviation unsustainable if this were happening in the real world.

So my recommendation is always to tamp down the turbulence effect to around 15%...  This will give you the effect of turbulence without making the airplane unflyable.

 

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34 minutes ago, rsrandazzo said:

(...)

So my recommendation is always to tamp down the turbulence effect to around 15%...  This will give you the effect of turbulence without making the airplane unflyable.

 

Capt. Randazzo,

Many thanks for your explanation - highly valuable and what I was looking for. 

If I may ask 1 more question on the Turbulence front: Will my 747QOTSII react to the simulated weather by AS outside of just bouncing around. As in, will the airframe fail more quickly, or have more "service based failures" if I flew it in adverse weather everyday vs clear and blue skies? Im curious if the weather set in the sim by AS has a direct impact on how the aircraft "lives and breathes" or it weather acts purely as a simulation method (adding much more bounce) without impact to the 747QOTSII's overall health. 

I know you guys are always creating stuff that is "ahead of its time," so Im curious as to the relationship between the aircraft itself and the weather.  

Many thanks again! You guys are rad af!

Max Castro

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Max, to my knowledge there is not any structural failure mode included in the simulation. Realistically, you'd have to have something worse than a severe encounter with turbulence to warrant an airframe inspection.  Most do not appreciate how much of a beating these aircraft can take in the air...., now landing is different.   One can send the bird to maintenance very easily.

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Max,

Dan is pretty much spot on in his reply.

Airplanes that get shaken around or subjected to constant vibration tend to experience more mechanical failures and airframe cracking than those that do not- but there really isn't a good way to impart anything outside the statistical norm due to the lack of accuracy in the modeling of turbulence.

Instead we use a statistical failure model that is based upon real world failure rates for various components on the airplane- so what you are getting more closely approximates the actual fleet experience globally.

 

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On 11/29/2017 at 5:28 PM, downscc said:

Max, to my knowledge there is not any structural failure mode included in the simulation. Realistically, you'd have to have something worse than a severe encounter with turbulence to warrant an airframe inspection.  Most do not appreciate how much of a beating these aircraft can take in the air...., now landing is different.   One can send the bird to maintenance very easily.

Dan - thanks very much - greatly appreciated!

 

Happy Holidays,

Max Castro

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On 11/30/2017 at 9:27 PM, rsrandazzo said:

Max,

Dan is pretty much spot on in his reply.

Airplanes that get shaken around or subjected to constant vibration tend to experience more mechanical failures and airframe cracking than those that do not- but there really isn't a good way to impart anything outside the statistical norm due to the lack of accuracy in the modeling of turbulence.

Instead we use a statistical failure model that is based upon real world failure rates for various components on the airplane- so what you are getting more closely approximates the actual fleet experience globally.

 

Capt. Randazzo,

Thanks again for your insight - very much appreciated. 

Happy Holidays,
Max Castro

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On 29/11/2017 at 7:17 PM, rsrandazzo said:

The effect of icing on the airframe is done by FSX/P3D adding the weight of the ice to the airplane, but doesn't have any airflow/lift penalty, which is the primary negative interaction of airframe icing in the real world...

Does it mean that the Queen's Anti-Ice system actually works in P3D V3.4? Will I get the WAI and NAI green indications on the EICAS automatically when the airplane senses that FSX/P3D is adding ice?

I'm asking because I've never seen it happen using the Auto anti-ice, unless I manually set it to on.

Regards,

Fabrizio Barbierato

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