Undercarriage Textures & Animations

08 Aug 2016 14:33 #30320 by Algernon
In view of the release deadline within a week, I'm getting one of the big jobs on the Lightning out of the way - the undercarriage.

Scott, do you have any close-up photographs I could use for textures - at the moment, everything is white except for the tyres - and photo textures here would be really handy.

The wheel hub discs are missing, I intend to put those in, and hope to get decent compression animations too. Also, a more realistic sound would be brilliant, but I'm not sure where to get a good recording of that kind of thing... it's always been the trickiest bit of sound in FG for me...

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08 Aug 2016 14:47 #30321 by Algernon
Have already checked out your video on the subject, by the way, that will be useful! :)

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08 Aug 2016 15:41 #30323 by StuartC
remove the f6 set file from the public release.

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08 Aug 2016 15:44 #30324 by Algernon
Yep, done - I'm actually rebuilding the directory structure - maintaining the ability to share things between the two, but trying to improve the folder structure a bit.

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08 Aug 2016 21:39 - 08 Aug 2016 21:57 #30329 by ScottBouch
Hi Algy, check you emails dude!

I've sent you a selection of images of XS458 that show the undercarriage and wheel bays.. hopefully between them you may have something useful.

But here's a taster for the wheels and colossal brake units (8 pistons acting upon a stack of 4 disks with pads sandwiched in between each disk!):

The little wheel running against the rim is a "Maxaret", an early ABS system. It notices sudden deceleration of the wheel (ie: it's skidded and locked up) and would release the brake pressure. Not bad for a 1950's hydraulic design!






Cheers, Scott.
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08 Aug 2016 22:01 - 08 Aug 2016 22:23 #30330 by ScottBouch

Algernon wrote: Also, a more realistic sound would be brilliant, but I'm not sure where to get a good recording of that kind of thing... it's always been the trickiest bit of sound in FG for me...


Silence is the most realistic sound. Apart form a slight bump sound when locking down and up, and the the main wheel doors closing.

They are hydraulically actuated, the hydraulic pumps are driven directly from the engines so make no special undercarriage noise, they are as quiet as mice. Even if there was a tiny noise for travel, you'd never hear it above the engines. I'm not even sure you'd hear the bump with the engines running and in flight. We only have heard the bump when cycling the undercarriage on the jacks, using an external hydraulic pump.

Cheers, Scott.

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08 Aug 2016 22:03 - 08 Aug 2016 22:10 #30331 by ScottBouch
Are you going to town with animating the retraction or just Oleo extension / compression?

I ask because retraction is going to be fairly complex regarding working out main pivot angles (upward, and outward) to get the wheel in the wing flat. and then there's the folding strengthening arm, it's upper pivot point rotates in two axes as the leg retracts.

Cheers, Scott

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08 Aug 2016 23:10 - 08 Aug 2016 23:12 #30334 by Algernon
I've attempted to emulate a video of an F6 taking off and retracting its gear - it needs some work and polishing, but as least it nearly fits in the hole!!


ScottBouch wrote: Silence is the most realistic sound.

Excellent news!! ;)
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09 Aug 2016 08:21 #30339 by ScottBouch
That looks really nice!

Here's one more texture... this was in with the files I sent to you, it shows a small amount of dirt splatter under the wing and flap in line with the main wheels!


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09 Aug 2016 10:13 #30345 by ScottBouch
I should have mentioned that the yellowish colour showing through in patches on the legs is the undercoat / primer where the silver / grey top coat gas been rubbed away over the years.

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09 Aug 2016 10:25 - 09 Aug 2016 10:27 #30346 by ScottBouch
Typical undercarriage grease and grime on the underside of the walking joint of a main leg!

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09 Aug 2016 10:29 #30348 by ScottBouch
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09 Aug 2016 10:48 #30352 by ScottBouch
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09 Aug 2016 11:22 #30358 by Algernon
Well, THAT one is definitely going to come in handy! :)

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09 Aug 2016 11:52 - 09 Aug 2016 11:53 #30359 by ScottBouch
To help understand how the nose leg doors close..

You can see the two struts from the nose leg to the trailing door, these simply drag it closed.

The two "prongs" on the leg sticking down toward the tyre make contact with a simple spring loaded bar inside the wheel well, which is connected to the two front doors, so these doors only start to move when the leg is going through it's last couple of degrees of motion.

The linkages around the leg are important, there is a small piston that forces the nose wheel straight when the leg starts to retract, otherwise if the wheel was off to one side, it's crunch the airframe!

Cheers, Scott

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09 Aug 2016 12:13 #30361 by Algernon
Roger that. Impeccable timing, sir, I have just been pondering on the nosewheel actually, from a number of angles. Our gear door needed fixing to some extent, which I've done, and it will be quite fun to code in the quirks.

So, did you say the nosewheel was free castering? Is there a way to lock it in place so it doesn't move about between weight-off-wheel and retraction?
I'm looking forward to the nosewheel steering being removed and replaced with realistic differential braking - but I bet nobody else is, hahaha! To be honest, the differential braking is not great on our Lightning owing to the gear being quite close together, it might need to be augmented with a sneaky bit of assisted castering, but I shall try without first. I guess the slightly odd taxiing system is why you always see display Lightnings bobbing up and down a lot when moving about on the ground...

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09 Aug 2016 12:22 - 09 Aug 2016 12:22 #30362 by ScottBouch

Algernon wrote: So, did you say the nosewheel was free castering?

Yes.

Algernon wrote: Is there a way to lock it in place so it doesn't move about between weight-off-wheel and retraction?

Nope, but the wind may keep it fairly straight though? or may blow it about a bit?

Algernon wrote: ...the differential braking is not great on our Lightning owing to the gear being quite close together...

Yes, it's not great on the real thing either!

Algernon wrote: , it might need to be augmented with a sneaky bit of assisted castering, but I shall try without first.

It mat be helped by using a progressive braking input to the PC, such as the handle on the stick as I've been talking about int he hardware integration. a direct on / off won't be helpful at all.

Algernon wrote: I guess the slightly odd taxiing system is why you always see display Lightnings bobbing up and down a lot when moving about on the ground...

Absolutely correct!!

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09 Aug 2016 12:37 - 09 Aug 2016 12:38 #30363 by ScottBouch
Here's the door action from 8:55, unfortunately the forum doesn't support starting at a certain time:



Try this link instead

Cheers, Scott.

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09 Aug 2016 14:24 #30367 by ScottBouch
I'm sure at my folks house we have an old VHS or two of us doing undercarriage retractions on XS452 and XS458... It'd be great to find them and produce them into digital videos!

I also have an old shoe box full of photos that need scanning in too... the days before digital media!!

Cheers, Scott.

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