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Cedric Sin

Is the wing dropping too much on ground?

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Dear PMDG,

 

I've noticed that the PMDG 747 has quite a bit of wing drop when the aircraft is on the ground compared to the real thing, it almost looks like an elephant is standing at the wing tip and dropping the wing. I've attached two pictures, one from the real thing and one from the sim for comparison. I tried loading the aircraft with only 20t of fuel and still it looks the same as shown below. Is that meant to be like this or is something wrong with the installation? Much appreciated.

 

Regards,

Cedric

 

96925.jpg

32628998922_76a7c99636_h.jpg

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2 hours ago, bjapp677 said:

Unfortunately they SEE DATA ONLY...

Please do not start again the same discussion. Yes we need DATA period.

  • Upvote 1

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Hello,

While it's pretty clear that the wing droop too much, when I reported this issue to PMDG support over a year ago, I was explained it was done as best they could. Actually, the main reason for this would be yet another limitation of our simulation Platform, as fuel doesn't take up 3D volume in FSX/Prepar3d, it makes it particularly complicated to properly nail the flex effect from the fuel in the wing spar, as its volumes increases.

 

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On 2/8/2017 at 8:51 AM, Cedric Sin said:

I've attached two pictures, one from the real thing and one from the sim for comparison

How much exactly is in the wing in the first picture?

How much exactly is in the wing in the sim picture?

Can you verify that these match?

If your answer to the first question is "well, based on the assumption that such-and-such airline uses a generic minimum fuel value of X, and this plane just landed after a flight from Y, then it should have about X in it." That is completely irrelevant.

If you're going to compare two pictures, then you need to provide evidence that the images show the same condition. So far, there is no proof. The wing in the actual image could be entirely different in fuel weight from the one in the sim. In that case, the images are about as relevant to the discussion as a comparison to a 787 wing is.

8 hours ago, bjapp677 said:

Unfortunately they SEE DATA ONLY...

"Unfortunately"?

So we should build our planes off of "screw data entirely," and go "go with your gut?"

This 747 with gobs and gobs of thrust feels right, based on zero data, verified by a bunch of forum members making baseless assertions...so...put a gold star on it and ship it! Sorry...no...that's not how life works, and it's not how we work.

If you're suggesting that we don't base our products on data, and, instead, simply go off of the dataless opinions of random passers-by in the forum, I don't even know what to say...I guess I'll go tell our Tech Team that their services are no longer needed because our forum members who provide zero data clearly know better.

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3 hours ago, scandinavian13 said:

"Unfortunately"?

So we should build our planes off of "screw data entirely," and go "go with your gut?"

I'm sorry but this gave me the best laugh I have had all day :)

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9 hours ago, raflucgr said:

Hello,

While it's pretty clear that the wing droop too much, when I reported this issue to PMDG support over a year ago, I was explained it was done as best they could. Actually, the main reason for this would be yet another limitation of our simulation Platform, as fuel doesn't take up 3D volume in FSX/Prepar3d, it makes it particularly complicated to properly nail the flex effect from the fuel in the wing spar, as its volumes increases.

 

The mass distribution of fuel along the wing can be modelled mathematically and does not need to be part of the simulation platform created by placing 3D volumes of fuel. In the same way that the mass distribution of passengers and cargo does not have to be simulated by 3D models.

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...grabs popcorn... suggests be careful of fish-eye lens effects...

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Posted (edited)
1 hour ago, kevinh said:

The mass distribution of fuel along the wing can be modelled mathematically and does not need to be part of the simulation platform created by placing 3D volumes of fuel. In the same way that the mass distribution of passengers and cargo does not have to be simulated by 3D models.

Hi Kevin,

I am just repeating what I was told by Ryan back then. To be honest, I have never been fully convinced by this explaination but considering my knowledge in flightsim modeling is close to nonexistent, I couldn't venture to suggest how it should be done. This being said, I think you have got a very valid point and it might be interesting if anyone from PMDG was willing to shed some light on how they modeled the behavior of the wing when it comes to weight distribution and flexing. Over the weekend, I will go and try to find some more solid evidence that the wing spar droop is a bit too pronounced.

Edited by raflucgr

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Posted (edited)

I would suggest trying to load 0 fuel into the PMDG aircraft and have a look at the wing then.  That way you are almost guaranteed that the aircraft in photos has more fuel in the wing than PMDG. 

However, as has been said a lot of times here by PMDG, they want data, not just subjective photos and eyeballing.

Edited by VHOJT

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8 minutes ago, VHOJT said:

 

I would suggest trying to load 0 fuel into the PMDG aircraft and have a look at the wing then.  That way you are almost guaranteed that the aircraft in photos has more fuel in the wing than PMDG. 

 

Still hanging down... but that‘s based on a look, on pictures.. there might be an angle issue, zoom factor... and so on. RSR said they were looking into it so actually there is no need to argue. Until then I remain on the flight deck :D

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3 minutes ago, Ephedrin said:

Still hanging down

What difference does it make?

blaustern

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1 hour ago, Bluestar said:

What difference does it make?

blaustern

None to me. I don‘t see the wings anyway from the cockpit. 

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7 hours ago, Ephedrin said:

Still hanging down... but that‘s based on a look, on pictures.. there might be an angle issue, zoom factor... and so on. RSR said they were looking into it so actually there is no need to argue. Until then I remain on the flight deck :D

Did he really say this ?

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13 hours ago, Ephedrin said:

None to me. I don‘t see the wings anyway from the cockpit. 

The only folks that really know are the structural engineers at Boeing.  Anyone else is just speculating.  :smile:

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57 minutes ago, Bluestar said:

The only folks that really know are the structural engineers at Boeing.  Anyone else is just speculating.  :smile:

absolutely true.

And even the same model may have gone through revisions and may have been subject to changes that have consequences for the wing flex. 

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Gents,

You guys will be nasty to one another about literally ANYTHING.

As the guy who coded the wing flex, yes- I think the impact of static droop is too much.  It is something I have continued to play with and improve over time.  The version of this that will roll out with the 748 release is much closer to correct, I believe.

For all the know-it-alls (and since you know-it-alls know-it-all, you know I'm talking to YOU...  :laugh:) One of the reasons there is too much static flex is because of our efforts to tame the COMPLETELY BOGUS turbulence effects of the variou weather engines.

I spent about a month creating a process that will dynamically adjust the stiffness of the spar based on how high on the "Ridiculous Scale" the wing flex goes because of bogus weather engine turbulence.

It isn't perfect and definitely has it's flaws- but I got bored and started thinking about ways to try and make our product look and behave correctly in spite of the ridiculousness of 15-20G turbulence bursts that are so favored by the weather engines.  So I created a deflection scale (actually called it the Scale of Turbulence Ridiculousness) and the damping mathematics work downward from there.  :ph34r:

So stop beating one another over the head for stupid stuff, will you?

 

 

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Posted (edited)

That is really interesting about the turbulence!  Pity the weather engines don't do the turbulence better.  But the wing flexing up and down while you taxi looks damn good! 

Edited by VHOJT

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There must be a reason as to why the weather engines exaggerate this effect. Perhaps it's hard to get right, without some kind of built-in factor within the system?

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Posted (edited)
9 hours ago, rsrandazzo said:

Gents,

You guys will be nasty to one another about literally ANYTHING.

As the guy who coded the wing flex, yes- I think the impact of static droop is too much.  It is something I have continued to play with and improve over time.  The version of this that will roll out with the 748 release is much closer to correct, I believe.

For all the know-it-alls (and since you know-it-alls know-it-all, you know I'm talking to YOU...  :laugh:) One of the reasons there is too much static flex is because of our efforts to tame the COMPLETELY BOGUS turbulence effects of the variou weather engines.

I spent about a month creating a process that will dynamically adjust the stiffness of the spar based on how high on the "Ridiculous Scale" the wing flex goes because of bogus weather engine turbulence.

It isn't perfect and definitely has it's flaws- but I got bored and started thinking about ways to try and make our product look and behave correctly in spite of the ridiculousness of 15-20G turbulence bursts that are so favored by the weather engines.  So I created a deflection scale (actually called it the Scale of Turbulence Ridiculousness) and the damping mathematics work downward from there.  :ph34r:

So stop beating one another over the head for stupid stuff, will you?

Does Kyle know this? Your thought's that is, not that you coded it, lol?

Quote

 

 

 

Edited by YMMB

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