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rsrandazzo

[26JAN18] ...These are a few of our FAVORITE things...

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Captains,

A reviewer reached out to me last week and asked if I would mind reading through his review of the PMDG 747-400 Queen of the Skies II and let him know if he had missed any details in the airplane that I thought his readers might be interested to learn.

I politely declined, but we bounced a couple of email back and forth in which I asked random questions such as "did you see <insert something>" or "did you notice that when you <insert action> the simulation will <insert re-action>" and "Oh don't forget to take a look at <insert something> because nobody seems to have noticed that yet."

He was a good sport with my gentle prodding around the soft spots- because both of us are dancing around the fact that he is not a 747-400 captain, hasn't a pilot's license and in spite of being a great review writer and an all around nice guy who absolutely LOVES airplanes- his level of knowledge of the airplane and our software could never be granular enough for him to see and absorb all of the rich little goodies we pack into our simulations for you.

That got me thinking:  What is my favorite part of our 747-400 simulation, and what of the thousands of tiny details that we painstakingly research and put into our products have you guys noticed that you really and truly love?

Okay- so here are a few of mine...  Feel free to add yours, too.

FUEL DENSITY MODEL:  This is one of my favorites because it came to me during a fuel stop a number of years ago in which I began to ponder the difference in fuel density as you move around the globe.  It became sort of a pet interest...  The sort of thing you read up on when you have FAR more important things to do because it tickles the nerd funny bone.  What resulted was a three dimensional algorithm that models real world fuel density based upon where on the planet you take on fuel in the 747-400.  (Real time fueling only...  I left instant fueling at standard density as a fallback in case anyone got into trouble, or the model did anything unexpected...)

Some of you are probably scratching your head and wondering WTH fuel density has to do with anything...  The simplest way to think about it is to imagine it as the amount of weight per gallon of fuel.  If you have a 10gal fuel tank, and you put fuel into that tank that weighs 6.7lbs/gal then you have 67lbs of fuel.  if your engines burn 67lbs/hr, then you have 1hr of fuel onboard.

If you laoded fuel into that same tank that had a density of 6.2lbs/gal, then you only have 62lbs of fuel... and you will burn your fuel in about 56 minutes...

Extrapolate that out to something the size of a 747-400 and you can see that if you get fuel in Beijing during the summer time and your density is 6.3lbs/gal, you have significantly less range capability than you would if you fuel in Seattle in winter and get a density of 6.85lbs/gal.

If you aren't flying out to maximum range, none of this really matters much- but it is still pretty nerdy and fun once you start paying attention to it!  :cool:

 

FUEL TEMPERATURE MODEL:  This is another nerd-fest that I engaged in during the design of the 777, but that wasn't really ready for full use until late in the 747-400 development.  Our fuel system looks at fuel temperature for each tank.  Each tank has a temperature change rate based upon the tanks exposed surface model, and the main tanks have some heat exchangers for oil and for hydraulics that are constantly providing warmed fuel back into the ecosystem of the tank....

The end result?  As fuel begins to move throughout the airplane in flight, you get a range of temperatures for your fuel.  The 747400 only has a single fuel temperature readout- but the 747-8 has sensors in all tanks and does some predictive work to make sure that when your RES tanks begin to transfer fuel into MAIN 1 and MAIN 4 (just like the 747-200!) that the fuel temperature in those tanks won't drop below a pres-set value in order to minimize the risk for fuel icing.  All of this is modeled and you can get a couple of different eicas messages (and associated electronic checklist procedures) from the 747-8 on polar flights...

Like the density model, we have created a fuel temperature model for fuel coming into the airplane during real time fueling- and you can see the temperature changing as the new fuel is added.

All of this is done using proper physics and some pretty in depth fluid mechanics to account for mixing of fuel as a result of flow-through different locations on the airplane.

 

THINGS THAT WIGGLE:  Anyone notice the animation on the body gear during liftoff yet?  Their motion is not attenuated by scissor strut pressure like the wing gear is...  Makes for some neat animation when the airplane leaves the ground.

(Did anyone ever notice the cantilever gear animation on the 777-300?  A TON of work went into getting that correctly...)  :blink:

 

So... Tell me...  What have you guys noticed in the tiny details that you love about the 747-400 simulation?

I'm fascinated to know what you guys have noticed and what made you notice it.

 

 

 

 

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Robert S. Randazzo coolcap.gif

PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

You can find us at:  http://forum.pmdg.com

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Bam!  First again!!  Nice post Double R

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Dave Robertson

BE20, BE35, BE02, C560, CRJ, MD80, E190, B777

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15 minutes ago, rsrandazzo said:

What have you guys noticed in the tiny details that you love about the 747-400 simulation?

Maybe not a little thing to most folks, but the most important thing to me - It flies well.   :smile:

But what do I know I learned to fly in the Army.  :biggrin:

blaustern

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I Earned My Spurs in Vietnam

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1) During a climb with the 747, with low center  tank fuel,  fuel low in center tanks EICAS message that disappeared when I leveled off at cruise.  So:  fuel sloshed away from pumps in climb, but came back to pump intakes when in level flight.

2)  The other day I was simulating a RW flight westbound using the 777 over Iceland and Greenland (RW aircraft was an A330).  The RW aircraft was ahead of me, and I noticed that oddly it descended from FL360 to FL320 way before normal TOD.  As I crossed Greenland,  I got my answer: low fuel temperature EICAS message, necessitating a temporary descent to FL320. 

Mike

 

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To further my overexcited post - my favorite part of any aircraft - simulated or real - is the landing gear. I remember my first walk around on the 777 in YVR and thinking to myself “wow”. We are going to pull this aircraft in to the air in about 40 minutes. Landing gear always amazes me for a multitude of reasons - most importantly the impact it takes - the energy is absorbs and the the energy the associated components can dissipate. Just pause for a moment and think about that.  Think about the landing gear and the important role it plays - then hop in to your sim and grab your avatar and have peek at the gear on the 744 or 77W and walk around it. The 744 landing gear was a thing of beauty!  Center bogies that move to assist with ground handling - amazing!!!  My two cents and i was still first thanks in part to some jet lag and my carcadain rhythm being a touch messed up!!

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Dave Robertson

BE20, BE35, BE02, C560, CRJ, MD80, E190, B777

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2 hours ago, Bluestar said:

Maybe not a little thing to most folks, but the most important thing to me - It flies well.   :smile:

But what do I know I learned to fly in the Army.  :biggrin:

blaustern

Wilhelm,

One of the things that we *ARE* going to bring you at a point in the not-to-distant future, is a sloppier flight model for the 744.  The 744 is actually a bit of a nuisance to fly well by hand.  Nothing wrong with it- just old fashioned hydraulics/tension cables and control inputs.  I have taken a couple people into the 777 sim, then brought them to the 744 and had them wonder what was wrong with the airplane.  The mechanical contrivances that keep the yoke centered in the role axis, for example, create a bit of an odd flat spot that you have to kinda work to overcome- and then you sometimes feel you have too much input so you roll it out and go over the tensioner again and back to square one, you haven't banked a single degree. 

Now the 748 on the other hand, flies much more like the 777, which is due in part to changes in the way the controls are managed. 

Funny stuff like that...  we will get there.  It is always a game of small changes!

 

 

  • Upvote 7

Robert S. Randazzo coolcap.gif

PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

You can find us at:  http://forum.pmdg.com

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2 hours ago, Mike777 said:

1) During a climb with the 747, with low center  tank fuel,  fuel low in center tanks EICAS message that disappeared when I leveled off at cruise.  So:  fuel sloshed away from pumps in climb, but came back to pump intakes when in level flight.

2)  The other day I was simulating a RW flight westbound using the 777 over Iceland and Greenland (RW aircraft was an A330).  The RW aircraft was ahead of me, and I noticed that oddly it descended from FL360 to FL320 way before normal TOD.  As I crossed Greenland,  I got my answer: low fuel temperature EICAS message, necessitating a temporary descent to FL320. 

Mike

 

Mike,

YES!  I'm glad you noticed the slosh...  You will see the fuel roll around the bottom of the tank, too, if you watch the PRESS lights carefully. 

This leads to another interesting item:  Have you noticed that the sloshing around hardly ever upsets the Warning/Caution/EICAS?  This is because we took great pains to correctly simulate the built in time delays for each individual message in the EICAS stack.  (Yes- every single one of them has a unique time delay... most just a second or two to eliminate false positives and transient messages- but some of them (normally in the fuel system) have very long delay times in order to allow for the motion of fuel in the tanks.

There is one message in the fuel system that has ten minutes of delay on it to make sure it isn't just reactive to a transient condition in the center wing tank.  I forget which one it was off the top of my head- but it is there...

 

 

  • Upvote 5

Robert S. Randazzo coolcap.gif

PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

You can find us at:  http://forum.pmdg.com

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I love it when these year old posts are resurrected :)

I noticed the fuel density and temperature when trying to bring the tanks in a hot part of the world.. wondering why on earth I couldn't cram anymore in when the tank capacity wasn't yet exceeded.. then of course it was pointed out to me why this was happening.. The lighting model and the curved displays for me really add some depth and realism too.. many other things that I could go on to talk about.


Cheers


Craig

 


Craig Read, EGLL

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4 minutes ago, craig_read said:

I love it when these year old posts are resurrected :)

Cheers


Craig

 

Craig,

DOH!  Fixed.  :ph34r:

 

  • Upvote 2

Robert S. Randazzo coolcap.gif

PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

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Not so deep into the systems I really love the display delay of the CDU and it being increased when it has to calculate in the background... adds so much to the immersion of sitting in the real one. 

Just one question: does the gear lever really need that much time to get stowed in the off-position? 


,

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Just watching the numbers slightly bounce on the MCP on the early models when you dial them into speed, heading, altitude.  It's a beautiful mix of old and new.

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LUIS LINARES

Processor: Intel Core i9 6700K 9900K (5.0 GHz Turbo) Eight Core; CPU Cooling: NXXT Kraken X62 280mm CPU Liquid Cooler; System Memory: 64GB Corsair DDR4 SDRAM @ 3200 MHz, RGB; Graphics Processor: 11GB Nvidia GeForce RTX 2080 Ti, GDDR6, Primary Drive: 2TB Samsung 850 Pro Solid State Drive (SSD)

 

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The sounds.... there are rumbles and whines and roars and oh my goodness, even a beat if you listen.  I always turn up the volume after a long enroute and before TOD to listen to the engines talk to me during descent and arrival. Gives me joy.

Air temperature modelling,  sitting on the Sydney ramp this time of year one must either get an air cart or run up the APU to keep the cockpit below 30C.  And of course the little bump to the set point while enroute to keep pax comfy and sleepy.

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Dan Downs KCRP

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Unfortunately we can‘t see the animation of the gear on instant replay. I would repeat it over and over. 

I always keep the flaps lowered and speedbrakes up for a while after landing, just to see the mechanical system.

 

Josef

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Josef Kolb - EDNV

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34 minutes ago, Cocobellomann said:

Unfortunately we can‘t see the animation of the gear on instant replay. I would repeat it over and over. 

I always keep the flaps lowered and speedbrakes up for a while after landing, just to see the mechanical system.

 

Josef

Josef,

Figuring out how to get our fully customized animation sequences to play with the replay logic is on my list of wants.  I will solve it one of these days.  The thing with software engineering is that you sometimes just need a free weekend and a fresh idea to crack the egg wide open.

The airplane nerd in me LOVES replays...

 

 

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PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

You can find us at:  http://forum.pmdg.com

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