Beginner's guide to editing "par" files

[aesmith]

Hi,

Is there a beginner's guide to tweaking .par files? There's a downloaded model where I'd like to increase the motor power a little, and the trim is wildly wrong so it needs up elevator all the time.

Thanks,

Thanks, TonyS

[lowglow]

Do you have a program for editing the par file?

[aesmith]

I was assuming they were editable with Notepad. They appear to be text files, for example the one that I was speaking about contains stuff like this .....

VERSION 1.0

INFO //Free Form Comment Area, does not change model
Name: HobbyZone Super Cub //Plane Name
Scale RTF ParkFlyer //Type of Plane
Spannweite: 1.20 m //Span (m)
Gewicht: .71 kg //Weight (kg)
Motorisierung: 480 //Engine
Prop: 10x8 //Prop
Akku: 7 cell //Battery (6 Zellen = 6 cells)
Kapazität des Akkus: 1000mAh //Battery Capacity

RC-Funktionen: //RC Functions
Kanal 1: Rudder //Channel 1 (Seitenruder = Rudder, Heckrad = tail wheel)
Kanal 2: Elevator //Channel 2 (Höhenruder = Elevator)
Kanal 3: Aileron //Channel 3 (Querruder = Aileron)
Kanal 4: Motor //Channel 4 (Motordrossel = Engine Throttle)

This model is modified from original and 4 channel with reduced dihedral.

3D Model Author: Gary Gunnerson //Model Author
e-mail: mailto:garyg51384@aol.com
WebSite: http://gunnerson.homestead.com/files/fms_models.htm
HobbyZone Super Cub: http://www.hobbyzone.com/rc_planes_hobb ... er_cub.htm

ENDINFO //ENDINFO, end comment area

// <ParEditor Ver1.6 2006-04-23 Masuoka Hideaki>
// ParEditor.Scale=119
// ParEditor.Data1= 0.6308 0.6308 0.3154 0.3154 0.9463 2.506 2.505
// ParEditor.Data2=0.1925 0.075 0.075 0.0144 0.0071 0.0379 0.308 0.7099
// ParEditor.Data3=0 0 0
// ParEditor.Data4=0 0 2 2 -1 -5
// ParEditor.Data5=2 -2 1 -1 0 0
// ParEditor.Data6=1 1 0 0 -2 1
// ParEditor.Data7=15 13.702
// ParEditor.Data8=0 0 0 0
// ParEditor.Data9=12 8 5 5
// ParEditor.Data10=-20 -20 -20 -20
// ParEditor.Data11=50 50 50 200
// ParEditor.Data12=30 30 30 30
// ParEditor.Data13=5 3 1 0.3

AIRPLANE

MAIN

0.71 //Mass [Kg]
0.0497 //Roll Inertia Moment Ixx [kg*m^2]
0.032 //Pitch Inertia Moment Iyy [kg*m^2]
0.0731 //Yaw Inertia Moment Izz [kg*m^2]
-0.00087 //Ixz [kg*m^2]
0 0 0 //dSˆÊ’uX,Y,Z [m]
0.23 //Height of Center of gravity [m]

[ggunners]

You will be much happier using .

-- ggunners

[aesmith]

That looks great, thanks. You wouldn't happen to know which parameter I should tweak for elevator trim do you? As I say that particular model needs a lot of back elevator, so there's not enough up travel for example for landing.

Tony S

[lowglow]

So the model is wanting to drop all the time? have you tried adjusting the trims on your txt?

[aesmith]

Cheers. Its improved by putting the trim all the way back, and increasing the control throws, but there's still not enough "up" for a proper tail dragger landing. I think what it needs is the centring of the elevator adjusted, and the travel increased.

[aesmith]

I'm starting to think it could be a transmitter interface issue. On reflection of course it can't be anything to do with trim, or offset or end-points on the transmitter, because those all get canceled out by the calibration routine on Smartpropoplus.

On the other hand, its only this one model that's affected, so tweaking the .par file to trim it up a little would fix things for me, hence my original question. I'm surprised that there's nobody who knows how to do that.

[lowglow]

Nah we know how to do that.
Just wanted to make sure you didn't have a tx or calibration problem first.
I will have a wee play with the par file to get it the way you want it, then I will show you how to do it

[ggunners]

Hmmm.... I just flew that model again on my machine and it flies neutral without extra elevator at full throttle.

If you are trying to do a 3-point landing with this one, it is extremely tough unless you move the CG backwards a bit and watch very carefully for a stall. This wing floats in ground effect. This is a 3 channel airplane, too slow and you have zero control authority.

In your .par example above. Try changing the CG backward just a bit and see what happens. First number -0.01 to start. More power, add one more battery to the .par file motor

-0.01 0 0 //dSˆÊ’uX,Y,Z [m]

To increase the elevator throw. Go to //Wing3 <STAB> and change the maximum angle from 10 to 12 or so.

12 //Maximum Angle [deg]

-- ggunners

[lowglow]

Wow adding that extra battery sure makes a diference