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Macchi-205MC Contact Points

falcon409

falcon409

Moderator
Staff member
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:
 
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
 
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
 
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
 
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:
 
falcon409 said:
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:
Click to expand...

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

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