Macchi-205MC Contact Points

[falcon409]

Did anyone ever fix the contact points for this airplane. It acts as though it's sitting on two big inner tubes when it taxi's, lol. You can't taxi any faster than a few miles per hour and try to turn or it does a wing-over and crashes. Just wondering.:salute:

[OleBoy]

One of the first things I noticed. Try this.

[contact_points]
static_pitch = 12
static_cg_height = 4.90927
tailwheel_lock = 0
gear_system_type = 1
max_number_of_points = 9

point.0 = 1, -11.8, 0, -1.71, 1600, 0, 0.531197, 41.64, 0.551117, 2.5, 0.686607, 5, 5, 0, 0, 0
point.1 = 1, 7, -5.3, -6.35, 1800, 1, 0.531197, 0, 0.9, 3.5, 0.274063, 4.1, 4.1, 2, 0, 0
point.2 = 1, 4.3, 5.2, -5.77, 1800, 2, 0.531197, 0, 0.9, 3.5, 0.274063, 4.8, 4.8, 3, 0, 0
point.3 = 2, -1, -21.6, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 5
point.4 = 2, -1, 21.6, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 6
point.5 = 2, -19.4, 0, 0.9, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 9
point.6 = 2, 0, 0, -2.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
point.7 = 2, 10, 0, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
point.8 = 2, 9.8, 0, -4, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4

[Z-claudius24]

Hello,

Those I use :

[contact_points]
static_pitch = 12
static_cg_height = 4.90927
max_number_of_points = 9

point.0 = 1, -16.2, 0, -1.10, 1600, 0, 0.531197, 60.64, 0.551117, 2.5, 0.686607, 5, 5, 0, 0, 0
point.1 = 1, 4.3, -4, -6.16, 1800, 1, 0.531197, 0, 0.9, 3.5, 0.274063, 4.1, 4.1, 2, 0, 0
point.2 = 1, 4.3, 4, -6.16, 1800, 2, 0.531197, 0, 0.9, 3.5, 0.274063, 4.8, 4.8, 3, 0, 0
point.3 = 2, -1, -21.6, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 5
point.4 = 2, -1, 21.6, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 6
point.5 = 2, -19.4, 0, 0.9, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 9
point.6 = 2, 0, 0, -2.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
point.7 = 2, 10, 0, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
point.8 = 2, 9.8, 0, -4, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
gear_system_type=1

[OleBoy]

Try these Ed. I'm having a hard time getting the inner tube effect out. Not sure what to change as it's trial and error

point.0 = 1, -11.8, 0, -1.9, 1600, 0, 0.531197, 41.64, 0.551117, 2.5, 0.686607, 5, 5, 0, 0, 0
point.1 = 1, 7, -5.2675, -6.4476, 1800, 1, 0.531197, 0, 0.5, 3, 0.274063, 4.1, 4.1, 2, 0, 0
point.2 = 1, 7, 5.3, -6.48, 1800, 0, 0.531197, 0, 0.5, 3, 0.274063, 4.1, 4.1, 0, 0, 0
point.3 = 2, -1, -21.6, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 5
point.4 = 2, -1, 21.6, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 6
point.5 = 2, -19.4, 0, 0.9, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 9
point.6 = 2, 0, 0, -2.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
point.7 = 2, 10, 0, 0.2, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4
point.8 = 2, 9.8, 0, -4, 1600, 0, 0, 0, 0, 0, 0, 0, 0, 4

[falcon409]

Yep, this is gonna take some work. So far nothing seems to work. . .the airplane is pretty unstable on the ground. If you zig zig down the rwy at greater than 10kts you get wing tip scrapes. . . .if you apply the brakes, the mains sink into the taxiway and then bounce back up like balloon tires. Any turns must be done with the aircraft at a crawl, otherwise it tips over and crashes. I don't understand contact points and won't even attempt to figure this out, so if anyone else wants to give this a go. . .or if you fixed this a long time ago and didn't post the fix. . . .please feel free now, lol.:salute:

[Milton Shupe]

I'll look at it ... where can I find this aircraft? Got a link?

[OleBoy]

This was sent to me from Mike Z via email. I can send if you pm me your email

[Milton Shupe]

PM sent

[OleBoy]

You should have received it by now Milton. If not, let me know

[Milton Shupe]

Downloaded ...

[mikezola]

Did anyone ever fix the contact points for this airplane. It acts as though it's sitting on two big inner tubes when it taxi's, lol. You can't taxi any faster than a few miles per hour and try to turn or it does a wing-over and crashes. Just wondering.:salute:

Greetings-
I know of the problem that you're referring to- but I had taken care of it! To make sure, I just flew it a few minutes ago after reading your post. Sure enough, I could pirouette her wherever I wished, with or without the differential brake that I put in the brake section. As I recall, as I was moving the points closer to where I wanted them(I didn't care for the original points, and had already started adapting the CFS2 1% files), I got more of the effect- until I moved 'empty weight CG position' forward quite a bit. Not being an expert either, I wasn't sure of the relation of the CG position to the ground behavior, but I couldn't argue with my result. If anyone else wants to try my FDE files, I'll be glad to send them a copy... Mike Z.

[falcon409]

Most definitely Mike, as it's too "wobbly" as is while on the ground.:salute:

[mikezola]

Most definitely Mike, as it's too "wobbly" as is while on the ground.:salute:
No problem- check your PMs. -Mike

[Milton Shupe]

Okay, check out Mike's work.

Having started this before Mike posted, I totally revamped the aircraft.cfg. Moved the reference point and CoG (+7' as it was behind the pilot), CoG, contact points, lights, crash points, pilot's viewpoint and VC placement, load station weight, brakes, fuel locations, effects, engine location, static height and pitch, ... I think that's it. I did not mess with the flight characteristics of the air file. Main focus was ground handling but did do the takeoff/landing routine to test it. Feels great to me but I do not know this aircraft. If you would like like further changes, let me know. I did leave the CoG at about 29% MAC as it felt good there.

[falcon409]

Milton, wish you wouldn't make this stuff look so easy, lol. Thank you for taking the time to do this.:salute:

[Milton Shupe]

When you put everything where it is supposed to be, it is fairly easy. The main issues with the original cfg were:

1) FS Reference and CoG were behind the wings and pilot. So for everything to work from there, wheels were out of whack with the visual model and the aircraft turned on the reference point rather than on the mains. Of course, when you change the reference, all other coordinates must change (lights, fuel tanks, engine locations, viewpoint, contact points, etc.).

2) The contact points were very weird. Left and right mains were not equidistant from the centerline of the aircraft, and one was specified as longer than the other. Also, the suspension indicated that the shocks were shot with virtually no damping of oscillations (tube tire syndrome).

Anyhow, I scrambled for almost two hours to get it all back together. Hope that helps. :)

[mikezola]

Milton- which airfile did you start with- mine, or the OEM? I'm just about to check out what you did... It just so happens that there's another aircraft I'm wrestling with that I'm working through the same grief on from the same authors! Mike

[Z-claudius24]

Hi,

The Veltro

http://simtube.com/video/4395/Macchi-205

[Milton Shupe]

Milton- which airfile did you start with- mine, or the OEM? I'm just about to check out what you did... It just so happens that there's another aircraft I'm wrestling with that I'm working through the same grief on from the same authors! Mike

Mike, it was the original package as far as I know.

[falcon409]

Milton, when you work through a problem like this, are you using a particular program (ie; airwrench or ACM) or do you just have a knack for numbers, lol.:salute:

[falcon409]

Hi,
The Veltro. . . .
Claudius, what soundfile are you using? It sounds more like a jet than a prop. . . . .just curious.:salute:

[Milton Shupe]

Milton, when you work through a problem like this, are you using a particular program (ie; airwrench or ACM) or do you just have a knack for numbers, lol.:salute:

I used Notepad; does that count? :-) No, I simply use lights to show me where the key things are, like Reference point, Center of Gravity, Main and Tail gear. From there the rest is easy.

EDIT: The reference can be anywhere, but that is your home base. I usually set mine at 25% MAC, and at the thrustline. Once you know where you are working from, then set the CoG at 25% MAC on the thrustline, or 1-2" below. The set your loads, fuel, gear and lights, engine location, and adjust View/eyepoint if necessary. Get rid of 5 decimal places, use no more than 2. Align your contact point data on the commas, use same number of decimal places to make it visually easy to read and detect mistakes. The original points had the left main brake set as 0, tailwheel, and the sound entry for the left main was also 0. Easier to catch that stuff when things are aligned.

[falcon409]

I used Notepad; does that count? :-) No, I simply use lights to show me where the key things are, like Reference point, Center of Gravity, Main and Tail gear. From there the rest is easy.
I know you're a very busy person, but sometime when you have the ability, I'd like to bend your ear on just how that works. I used to have ACM and loved it, especially for placing the shockwave lights, but it no longer works now that I've switched to a 64bit OS and airwrench might be a good one if I really understood what I was changing, lol.

Anyway, thanks again for the work you do, pretty amazing.:salute:

[OleBoy]

Milton,

What a difference it makes with the new settings. A complete and different aircraft all together. Thanks for taking the time to go through it. :)

[Milton Shupe]

I know you're a very busy person, but sometime when you have the ability, I'd like to bend your ear on just how that works. I used to have ACM and loved it, especially for placing the shockwave lights, but it no longer works now that I've switched to a 64bit OS and airwrench might be a good one if I really understood what I was changing, lol.

Anyway, thanks again for the work you do, pretty amazing.:salute:

Thank you. I would be happy to help. The more of us who can do this, the better off we all will be. Just some basic concepts and understanding is all that is needed, Sparks has this on his website but any graphic to help understanding is better. This shows reference point at the nose. I just always place the aircraft in gmax at the centerline, thrustline, and 25% MAC. Makes everything easier to place for me. Of course, on my models, I get the basic coordinates out of gmax.

Thanks Oleboy. :)