Author Topic: Stop position per airframe basis  (Read 2386 times)

BJHawk

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Stop position per airframe basis
« on: September 13, 2018, 07:25:16 am »
Hi,
I was making config file for Mega Airport Prague LKPR to support GSX L2 and was hoping there would be option for diferent stop position for different airframe. IE in aformentioned scenery on Gate 4, there are diferent stop positions for 772 and 747 among others that correspond with the scenery's own VDSG stop position. Now when I set this gate up in GSX with 747 so the nose wheel and scenery's VDSG is correct and then try it with 777, the 777 is needed to move forward for the VDSG and ground markings to match the plane. When I change it in GSX and then try it with 747, the plane is too far in and needs to be moved back. Now, I know I am asking for too much and that there surely is compromise with either one being correct with VDSG and ground markings or for both being somewhere in the middle using only GSX VDSG. But that's not what I am aiming for.

virtuali

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Re: Stop position per airframe basis
« Reply #1 on: September 14, 2018, 01:37:54 am »
Please read the GSX manual, the explanation of how the stop position in GSX works, and its relationship to the airplane door and which one is the preferred exit.  Page 39, the chapter named "Understanding the Stop Position".

BJHawk

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Re: Stop position per airframe basis
« Reply #2 on: September 14, 2018, 08:39:20 am »
Yeah, your answer and manual are just as useful as Windows Tech Support in non-English.....

Here is what I'm talking about. 747 is setup in correct parking spot with Exit 1 set as prefered exit. On the next two screens the 772 is in the GSX ?perfect parking? position, which is i assume your system calculated Stop position, with preffered exit 1 and 2. As you can see,it does not correspond correctly to the scenery ground markings. Setting it up with 747 exit 2 or setting it up with 772 with either preferred exit produces just as useless results as this. Now what, dear FSDT Support team, what am i doing wrong after reading you useful response and manual?

virtuali

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Re: Stop position per airframe basis
« Reply #3 on: September 14, 2018, 03:09:39 pm »
As you can see,it does not correspond correctly to the scenery ground markings.

As explained on the manual, GSX tries to align the preferred door of the airplane used to customize the parking, with the preferred door of the plane used. There's no guaranteed this would match the ground markings, for the following reasons:

- We don't know if they are accurate

- We don't know if they were made using the same strategy GSX use of aligning doors

- We don't know to which exit they were made. But we can probably guess this.

Quote
Setting it up with 747 exit 2 or setting it up with 772 with either preferred exit produces just as useless results as this. Now what, dear FSDT Support team, what am i doing wrong after reading you useful response and manual?

There are 4 possible combination in total for any given pair of airplanes (the one used to customize and the one used to use the parking) and are as follows:



As  you can see from this picture, there are two main cases and two variation each:

Use the same preferred exit as the one used to customize the parking ( the first two cases ), which results in nose gear positions which are very close, with the 747-400 having the nosewheel slightly ahead if 2nd door was used for both.

Use an airplane with a different preferred exit than the one used to customize the parking. In this case, the difference is much higher, and the result you obtained, seems to indicate you customized with the preferred exit on the 1st door, then used the 777 with the preferred exit on 2.

This means, GSX is working exactly as it supposed to work and it conforms what's explained on the manual.

In your screenshot, if I read the marking correctly, the 772 was supposed to end up with its nosgear ahead of the 744, not as much as the case when different preferred exits were used, but not as close as the case when matching preferred exit were used.

So, it seems these markings were simply not made with the same strategy GSX uses. The might be accurate or not, we don't know yet, but this strategy GSX uses is the only one that can be safely used worldwide and would almost always guarantee that, if you tested a jetway on an airplane type and it worked, you can be reasonably sure it will work with another airplane too, since the door will end up in the same position.

Applying some kind of offset to the airplane configuration, won't guarantee it will always work, because we'll be back again to rely on the accuracy (of the lack of it) or ground markings, made by a vast majority or different developers.

The ONLY possible solution that would possibly allow to customize every parking position to always match different airplane types that could work everywhere, would be allowing to set a LIST of offset for each plane allowed on a parking, and allow this to be eventually different for each parking. This might work, but it would require A LOT of customization work on your part!

So, we chose not to do it, at least for the moment, and rely on the door alignment strategy, which is already a BIG improvement over the default alignment strategy, which was to place the reference point of the airplane in the center of the parking, which is almost always wrong, since these data don't really have any meaning and any relationship with doors, which are the most imporant object we should try to align to.