Contact points in the Aircraft.cfg file
John Ward
For each contact point in an Aircraft.cfg file, there is a long string
of values.
I'm trying to amend one for a recent F-111 Panel I mentioned on the n/g,
which also included an Aircraft.cfg file......
Does anybody know which order those strings of values are presented in -
i.e. is the 1st on the longitudinal distance from the CofG, the 2nd one the
lateral distance from the CofG, the 3rd one the height above or below the
CofG......???
Also, does anybody know if a double-wheeled nose wheel is represented by
a single contact point, or two contact points?
I've only had an initial look at the aircraft, and the Aircraft.cfg file
that came with the Panel has the effect of having the aircraft's nose up in
the air, well clear of the tarmac, so I need to "tweak" one of the contact
points. :-)
Regards,
John Ward
MartinS@ms
downloading):
Example:
[contact_points]
point.0= 1, -18.0, 0, -3.35, 3200, 0, 0.50,180, 0.25, 2.5, 0.90, 1.0,
4.0, 0, 0, 200
Below is a description of each element of the example contact point
data set:
Parameter Element Description
1 (1) Class Integer defining the type of contact point: 0 = None,
1 = Wheel, 2 = Scrape, 3 = Skid, 4 = Float, 5 = Water Rudder
2 (-18.0) Longitudinal Position The longitudinal distance of
the point from the defined reference datum (feet). Positive is
forward (out the nose).
3 (0) Lateral Position The lateral distance of the point from
the defined reference datum (feet). Positive is starboard (right, as
viewed from the top with the airplane pointing "up").
4 (-3.35) Vertical Position The vertical distance of the
point from the defined reference datum (feet). Increasing the value
(i.e. towards zero - e.g. from -8.3 to - 8.0) brings the nosewheel
down.
5 (3200) Impact Damage Threshold The speed at which an impact
with the ground can cause damage (feet/min).
6 (0) Brake Map Defines which brake input drives the brake
(wheels only). 0 = None, 1 = Left Brake, 2 = Right Brake.1
7 (0.50) Wheel Radius Radius of the wheel (feet).
8 (180) Steering Angle The maximum angle (positive and negative) that
a wheel can pivot (degrees).
9 (0.25) Static Compression This is the distance a landing
gear is compressed when the empty aircraft is at rest on the ground
(feet). This term defines the "strength" of the strut, where a
smaller number will increase the "stiffness" of the strut.
10 (2.5) Ratio of Maximum Compression to Static Compression
Ratio of the max dynamic compression available in the strut to the
static value. Can be useful in coordinating the "compression" of the
strut when landing.
11 (0.90) Damping Ratio This ratio describes how well the
ground reaction oscillations are damped. A value of 1.0 is considered
critically damped, meaning there will be little or no osciallation. A
damping ratio of 0.0 is considered undamped, meaning that the
oscillations will continue with a constant magnitude. Negative values
result in an unstable ground handling situation, and values greater
than 1.0 might also cause instabilities by being "over" damped.
Typical values range from 0.6 to 0.95.
12 (1.0) Extension Time The amount of time it takes the
landing gear to fully extend under normal conditions (seconds). A
value of zero indicates a fixed gear.
13 (4.0) Retraction Time The amount of time it takes the
landing gear to fully retract under normal conditions (seconds). A
value of zero indicates a fixed gear.
14 (0) Sound Type This integer value will map a point to a type
of sound:
0 = Center Gear,
1 = Auxiliary Gear,
2 = Left Gear,
3 = Right Gear,
4 = Fuselage Scrape,
5 = Left Wing Scrape,
6 = Right Wing Scrape,
7 = Aux1 Scrape,
8 = Aux2 Scrape,
9 = Tail Scrape.
15 (0) Airspeed Limit This is the speed at which landing gear
extension becomes inhibited (knots). Not used for scrape points or
non-retractable gear.
16 (200) Damage from Airspeed The speed above which the
landing gear accrues damage (knots). Not used for scrape points or
non-retractable gear.
In addition to the specific data for each contact point, there are
"global" [contact_point] parameters that are also used:
Parameter Example Description
max_number_of_points max_number_of_points = 21 Integer value
indicating the maximum number of points the program will look for in
the [contact_points] section.
static_pitch static_pitch = 3.82 The static pitch of the
aircraft when at rest on the ground (degrees). The program uses this
value to position the aircraft at startup, in slew, and at any other
time when the simulation is not actively running.
static_cg_height static_cg_height = 3.015 The static
height of the aircraft when at rest on the ground (feet). The program
uses this value to position the aircraft at startup, in slew, and at
any other time when the simulation is not actively running.
gear_system_type gear_system_type=1 This parameter defines
the system type which drives the gear extension and retraction.
0 = electrical,
1 = hydraulic,
2 = pneumatic,
3 = manual,
4 = none.
Martin S.
(Hampshire, UK)
Mxsmanic
> Does anybody know which order those strings of values are presented in -
> i.e. is the 1st on the longitudinal distance from the CofG, the 2nd one the
> lateral distance from the CofG, the 3rd one the height above or below the
> CofG......???
From the default aircraft.cfg files:
//0 Class
//1 Longitudinal Position (feet)
//2 Lateral Position (feet)
//3 Vertical Position (feet)
//4 Impact Damage Threshold (Feet Per Minute)
//5 Brake Map (0=None, 1=Left, 2=Right)
//6 Wheel Radius (feet)
//7 Steer Angle (degrees)
//8 Static Compression (feet) (0 if rigid)
//9 Max/Static Compression Ratio
//10 Damping Ratio (0=Undamped, 1=Critically Damped)
//11 Extension Time (seconds)
//12 Retraction Time (seconds)
//13 Sound Type
John Ward
Thanks guys - fantastic.
I've adjusted them before, but hadn't recorded what I did, and it sure
can be a lot of mucking around if you're not being methodical/precise
enough!
Printed both of these, so that'll take care of that on any future
occasion.
Regards,
John Ward
<MartinS@MS> wrote in message
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donbutts
"Mxsmanic" <mxsm...@gmail.com> wrote in message
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I'm impressed JW. Thought it was well beyond a Queenslander ...
:-)
Butts
NZ
John Ward
To print something out, you mean?
Nah, piece of cake, mate - I've been practicing! :-))
Regards,
John Ward
"donbutts" <donney...@hotmail.com> wrote in message
news:8JV1n.29953$J64....@newsfe20.ams2...
Iain Smith
> Hi Martin and Mxsmanic,
>
> Thanks guys - fantastic.
>
> I've adjusted them before, but hadn't recorded what I did, and it
> sure can be a lot of mucking around if you're not being
> methodical/precise enough!
John, it might help to know (if you don't already - apologies if you do)
that you can make the adjustments while FS is running. I've done this
many times with success.
1. Having loaded the aircraft that needs adjustment, select the outside
view and note which wheels are wrong and whether they are buried in the
ground or floating above.
2. Now select a totally different aircraft and load that to the location
then minimise FS.
3. Go to the appropriate aircraft.cfg file and make the adjustments.
Save and close the cfg (you did remember to back it up didn't you?)
4. Bring up FS and select and load the aircraft you're working on in
outside view. FS will probably be paused so you'll have to unpause it to
see the result. If more adjustment is needed then repeat the procedure.
This saves the time taken to start up and close down FS. The important
point is that the aircraft you're working on must *not* be loaded in the
sim while you're altering the cfg. HTH.
Iain
Rugby, UK
John Ward
No, I didn't know that, and it sure would remove most of the "mucking
around" - thanks for pointing it out.
I just added the print to the other two.
In this particular case, since there were only three Class 1 entries
(wheels), and two of them had the same vertical height value, logic dictated
that they were the two rear wheels, so I made the vertical height the same
for the third wheel entry, as it therefore had to be the nose wheel.
As an aside to Donbutts - O.K., Butts, I admit it, mate - it wasn't
logic, just a wild guess! :-))
Bingo, it worked like a beaut, first time!
Regards,
John Ward
"Iain Smith" <iaindotsmithdotrugby@atbtinternetdotcom> wrote in message
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donbutts
"John Ward" <jrm...@tpg.com.au> wrote in message
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John Ward
two wheels, its treated as a single entity by the Flightsim' in the
Aircraft .cfg file, and therefore only one Contact Point entry.
I guess that's a lucky break for people like MikeW, who get around in
aircraft like those Antonovs, which seem to have several hundred rear tyres!
:-))
JW
"John Ward" <jrm...@tpg.com.au> wrote in message
news:4b48...@dnews.tpgi.com.au...
Tom Duhamel
> (wheels), and two of them had the same vertical height value, logic
I'm wondering what an horizontal height would be...
Tom :)
John Ward
I used that terminology because that's how the parameter's described in
the literature, so I thought I should be consistent.
But hey, I've been wrong before, mate. :-))
Regards,
John Ward
"Tom Duhamel" <tom420....@gmail.com> wrote in message
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MikeW
> Hi Iain (n.b. the correct spelling, mate :-) ),
>
At last! :-)
--
MikeW
Shrewsbury, UK
Any attempt to stretch fuel is guaranteed to increase headwind.
MikeW
>
> I guess that's a lucky break for people like MikeW, who get around in
> aircraft like those Antonovs, which seem to have several hundred rear
> tyres! :-))
>
....But still only have two front wheels! :-)
--
MikeW
Shrewsbury, UK
Remember, you're always a student in an airplane.
MikeW
> John, it might help to know (if you don't already - apologies if you
> do) that you can make the adjustments while FS is running. I've done
> this many times with success.
<snip>
Well I didn't know that!
Thanks Iain, very informative.
--
MikeW
Shrewsbury, UK
Just remember, if you crash because of weather, your funeral will be held on
a sunny day.
Iain Smith
> Iain Smith wrote:
>
>> John, it might help to know (if you don't already - apologies if you
>> do) that you can make the adjustments while FS is running. I've done
>> this many times with success.
>
> <snip>
>
> Well I didn't know that!
>
> Thanks Iain, very informative.
That's ok Mike. I can't make any claim to it as it was first posted here
some years ago by Fr. Bill Leaming, a one time regular on this NG and a
veritable fund of wisdom on FS and computing in general. :-)
Iain
Rugby, UK
John Ward
He SURE is, mate, and I, for one, wish he wasn't so busy with all his
various works that he had a bit of time for the n/g...!!
Regards,
John Ward
"Iain Smith" <iaindotsmithdotrugby@atbtinternetdotcom> wrote in message
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