Landing Gear Scissors in the Wiki

[Octal450]

Split off from the topic Boeing 777-200 , ER , LR , F , start of development 777X9. Quote added for context.

Hello to all
a drawing to explain Loked trak Scissors-parenting Flightgear may be useful for other aircraft

Have a nice day

Bonjour a tous
un dessin pour expliquer Loked trak Scissors-parenting Flightgear peut être utile pour autre avion

Bonne journée

https://1fichier.com/?hy1kfgxzd6j3hpdnwi1e

This is great info Franck, thank you! you should place this on the wiki! Maybe it'll help me finally fix the scissors on the MD-11.

Kind Regards,
Josh

[Johan G]

you should place this on the wiki!

It is already there, just not with a fully descriptive title, not in the best category (Aircraft enhancement, rather than Modeling) or with well placed links to it. In essence you almost need to already have seen in to find it again. While mostly being about animating gear scissors using the tracking animation the article is called Tracking animation (permalink).

So many articles are worse off though with cryptic names, absolutely no links to them and no category. Even more articles do not have a good introduction, so you have to skim through half the article to even see if it was the one you was looking for. Sorry for the rant, but it is frustrating me to no end and it would literally take manmonths to fix.


Edit: Moved the linked wiki article to a more descriptive title Howto:Animating gear scissors using the tracking animation, did a little cleanup and added the Modeling category (diff). Still, feel free to improve the article.

[LoCall]

Hello all
Hello Johan

It is already there, just not with a fully descriptive title, not in the best category (Aircraft enhancement, rather than Modeling) or with well placed links to it. In essence you almost need to already have seen in to find it again. While mostly being about animating gear scissors using the tracking animation the article is called Tracking animation (permalink).

For your information, Franck did start using the information on the very pages you are referring.
Correctness have been double checked.
But the result was : ...not working...

Feeding the console with the code (values properly updated) was resulting with : error line #1.
At line 1 you have : import("math");

Recooking that line did not helped
But removing that line have generated the expected code. ( if not needed - why it is on to that wiki page ?)

Further, the resulting code was improperly parsed. It had to be redacted and lined up/justified left ... ??? then it did worked. ( but no information about this in that wiki. )

Other errors / unclear / source of confusion are present in that article.
Again - no criticism - and thank very much to the unknown author.
But things always evolves, is it not ?

Last but not least, redacting an article written by some one else without having, prior, "a word" with him is not the best way to show respect, is it ?
This is not an ethic but a moral matter.
Having the "technical rights" to do edit the page is not the "whole" solution.
And as already said, the author of the said page is unknown...

This is what led Franck to offer a new wiki information.
It does sound to me very great and we should thank Franck for his work.

So ...

this, and many repetition of the very same event, with many users, led me to an idea that would benefit the whole community :

Information is true or wrong depending the age.
Things evolves and what was accurate then stop to be appropriate because a new reality supersede it.
...normal.

In this example, import("math"); does seem related to a former need of the nasal, at a time where we still had nasal able to run standing alone.
May we suppose that since then "everything" are intern to FG and no "import" is any more necessary ?

That would explain why line import("math"); do sort an error, today there is nothing any more to import ! but the old information is still in the wiki, is not ?
This leads to disappointment(s).

Of course anyone with a bit of "computer mojo" will come up with the solution.
But this defeat the goal of our wiki.

Of course any one with a good code mojo can re invent the whole FG wheel alone - if enough time . etc. etc. (theoretically)
The goal of the wiki is to avoid to have to re invent the whole, sharing the updated knowledge.

I believe "informations/wiki" authors (all) should be made aware that information is "age sensitive".

They should be invited to add [b]date[/b] to their information.

Then a status, ... pretty clear status ... should be on each pages :
a) maintained and information still up to date
b) not any more maintained - information may be already inaccurate
(because the "this page have been last edited the, is just failing his goal/purpose)

We could even put an auto / delay to swap from maintained / not maintained information.

This clear status "maintained/not maintained" could , in exemplis, allow to sort out and focus only on currently usable information and help a lot the maintainers to archive what should be.

We have a wonderful tool with this wiki.
But we hear so many time complaints about how outdated are and how not (any more) useful are theses informations
that it does not sound silly to wonder if we are not getting too close to some kind of obsessive excessive collection creating more difficulties than help.

Please, consider it, for the love our wiki.

LoCall

[WoodSTokk]

As far as i can see, Franck has added a different description how the locked-track animation work and show it nicely on gear scissors.
This information was allready there, but Franck use a different description and wording.

On the other side it will be nice if you say us about what wiki page you are talking about?
Because i have searched the animation page about locked-track animation and there is not one hit on 'import("math");'.
So i assume you are on a different wiki page?

[LoCall]

[url]
https://wiki.flightgear.org/Howto:Animate_gear_scissors
[/url]

[LoCall]

FYI
an easy trick to find it is :
in your favourite web search :
import("math"); site:wiki.flightgear.org
[ what you want to search for ] site:[the website where to search for]

the link does appears on 2nd position of that search

[LoCall]

On one hand you have several users trying to use the current wiki / information and failing ( I know 5 of them ).

On the other hand you have a new but working help/demonstration.

And the first reasoning is : it was already there - just the wording is different ???

If one do a search in his/her browser :
animate gear scissors site:wiki.flightgear.org

he.she obtain a myriad of links

the most recent wiki page
https://wiki.flightgear.org/Howto:Anima ... _animation
when yo click on the first link of included explanation you obtain

Page Not Found!

See if it exists in the old Wiki Archive
Search for this page title mentioned in other pages or related logs
Create this page

I do not know what else is needed in order to understand the real conversation is not about : the page was already there ...

We need a wiki that bring answers, not raise more doubts.

[LoCall]

ok gentlemen

closing on this topic (for my part) ( sorry I am still at work and my mind is half elsewhere ... )

I would assure each one of you I do really appreciate what each one do and have done in this community.
Do not get wrong imagining any animosity in my words.

I am just and really concerned about the quality of your wiki.

And I do not believe we are going to manage to make it better focusing on how close is Franck wording to the used by the former explanation.

The former explanation have stopped to work (and again it is normal evolution) and a day the Frank explanation is going to stop to be of help. it is normal.

What is missing to every "starting" / "young" user is a way to index a find the information without being drawn in anachronisms.

Cheers to all of you

(will now disconnect and try to end my work week)


Kind regards
LoCall

[WoodSTokk]

https://wiki.flightgear.org/Howto:Animate_gear_scissors

Sorry, but the information from Franck was not pushed on this site.
The last changes on this site was back in November 2019.
The correct page (where the information of Franck was added) is
https://wiki.flightgear.org/Howto:Animating_gear_scissors_using_the_tracking_animation

And yes, both pages describe how to animate the gear scissors.
But there is a big difference, the first one make use of standard 'rotate' animation with interpolation of pre-calculated values.
The second one describe how you can do that with the 'locked-track' animation (no pre-calculated values needed).
IMHO the 'locked-track' animation is absolutely the right way. As i created my first animation, i immediately recognized the difference and made all my animations as 'locked-track'. Pre-calculated values in this animation is pure guess work.
So please tell your friends about the 'locked-track' animation, they should forget the 'rotate' animation with pre-calculated values and try to animated it with 'locked-track'.
If you need examples of 'locked-track' animation, look at the gears of Citation II or A320-family or the canopy animation of the HK36.

PS: AFAIK the hack with pre-calculated values and 'rotate' animation comes from a time before FG had the 'locked-track' animation.
Nobody should use it today.

[WoodSTokk]

ok gentlemen

closing on this topic (for my part) ( sorry I am still at work and my mind is half elsewhere ... )

I would assure each one of you I do really appreciate what each one do and have done in this community.
Do not get wrong imagining any animosity in my words.

I am just and really concerned about the quality of your wiki. …

In one point i'm completely on your side and thats the age of information.
It is frustrating to search for information, you find one and try it hours or days and recognize at the end that this information is outdated long ago.
I had this not only in FG, also if something doesnt work on my Debian and i search for solutions i find dozens of HowTos but no one works.
Its real bad habit to not write a date into a HowTo. The FG wiki is a hotchpotch of new and old information because FG will be developed more than 20 years.
If something doesnt work, the best way is to ask in the forum or Discord.
I'm on Discord since some month and there are dozens of other aircraft devs (but also core devs) and we are working together and help each other.

PS: the FG wiki is a mess on some places but it is as it is.
If your knowledge is high enough and your english good enough, you can jump in and improve it.
FG will be build up of a group of enthusiasts.

[wkitty42]

And as already said, the author of the said page is unknown...

perhaps you should look at the wiki page's history? that "import(math)" line has been there since the beginning... i suspect specifically because the code is written for the external standalone nasal interpreter... not the nasal included inside FG...

T3r started the page 16 Feb 2009... he is an extremely well known user on these forums... the wiki has a different name from what he uses here because they are not connected to share the same credentials...
MILSTD made the next edit...
then Gijs made a few as well as Skyop, TheTom, Philosopher, Bugman, and then three years later, Johan G added an edit on 20 Nov 2019...
https://wiki.flightgear.org/w/index.php?title=Howto:Animate_gear_scissors&action=history

[WoodSTokk]

@wkitty
The problem is that we have 2 pages that describe how to animate gear scissors.
Go into the wiki and type 'gear scissors' in the search field.
The first 4 hits point to the old 'rotate' animation that use pre-calculated values for interpolation.
The fifth hit show you the 'locked-track' animation.
I think the 'locked-track' animation should come as the first hit.
And the old page should have a red hint box to inform you that this solution is outdated, please use 'locked-track'.
The old page is available to describe the old solution because there are many aircrafts that use it, but you should not use it for new animations.

[wkitty42]

@wkitty
The problem is that we have 2 pages that describe how to animate gear scissors.

i know this... i was only commenting about the erroneous statement that the original author of the original scissors gear page is unknown... one only need to use the wiki page's history button to see all of the edits done to the page and the original author is listed right there at the bottom as the first editor... the rest means nothing to me

[franck]

Hello to all
for info there is no need for
https://wiki.flightgear.org/Howto:Anima ... _animation
Tips
Graphic graph of coordinates of vertices of a line in angular coordinates according to the linear XYZ form
Strangely, the coordinates of the <track-axis> section do not seem to work on the coordinates given in the form: <x1-m> .. </ x1-m> ... <z2-m> .. </ z2-m >. We must give the coordinates in the form <x> ... </ x> ... <z> .. </ z>. To easily convert vertices, you can use the 3D CAD application FreeCAD. You create a line by inserting the two vertices (V1 and V2) and then activating the Bounding Box display, as shown in the figure. The 3 coordinates X, Y, Z can be used directly as x, y and z coordinates. But be careful with the signs.

Most of us have trouble with blender, if we can avoid giving a software in addition and especially which is not useful for this article
the axis we give 1 to the desired axis either x or y or z for track-axis
it is enough to ... you know no need to mark it to you

thank you for reading

[Octal450]

Title edited so it makes sense.

Kind Regards,
Josh