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Quote:
Originally Posted by sas550
Same for me, I double checked and the CG entry is empty, using 737-700 Opensky and S.Reyling 700.
It is an important data and no pertinent data to figure it.
FS9 fuel and payload window shows where the CG is on a rough little scale.
How to interpret it in % is a mystery to me.
That little scale shows you your MAC% although it doesn't say what it is. The more back it is the greater the Mac%. Because it is expressed as a percentage relative to the forward MAC limit. See the glossary item MAC.Quote:
Originally Posted by Jackpilot
And oops :oops: the formulae below was mixed up, but I corrected it.
Well, I can follow that...BUT where can I get those numbers (except the gross weight)
for the simulated airplane.
JP
I made a little example, hope it is clear. I can't still figure out where the AFT MAC setting comes from.
From aircraft.cfg:
Code:
[WEIGHT_AND_BALANCE]
station_load.0 = "170.0, 80.0, -2.0, 0.0, Pilot" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.1 = "170.0, 80.0, 2.0, 0.0, Co-Pilot" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.2 = "1250.0, 60.0, 0.0, 0.0, Crew" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.3 = "5200.0 , 22.0, 0.0, 0.0, First Class" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.4 = "11549.0 , 11.0, 0.0, 0.0, Business Class" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.5 = "15305.0 , -22.0, 0.0, 0.0, Coach 1-16" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.6 = "15305.0 , -38.5, 0.0, 0.0, Coach 16-29" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.7 = "6000.0 , 47.0, 0.0, 0.0, Forward Cargo" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
station_load.8 = "45000.0 , -67.0, 0.0, 0.0, Aft Cargo" //Weight (lbs), longitudinal, lateral, vertical positions from datum (feet)
max_gross_weight = 656000 // (pounds)
empty_weight = 314000 // (pounds)
[airplane_geometry]
wing_root_chord = 42.0 //Feet
wing_pos_apex_lon = 15.0 //Feet, longitudinal distance from reference point, negative going aft
Now an example using the above weights and arms:
Moment = Weight x Arm
Code:
Weight (lbs) Arm (ft) Moment (Lb*Ft)
Pilot 170 80 13600
Co-Pilot 170 80 13600
Crew 1250 60 75000
First Class 5200 22 114400
Business Class 11549 11 127039
Coach 1-16 15305 -22 -336710
Coach 16-29 15305 -38.5 -589242.5
Forward Cargo 6000 47 282000
Aft Cargo 45000 -67 -3015000
TOTAL: 99949 -3315313.5
PAYLOAD 99949 (PILOTS, CREW, PAX and FREIGHT)
EMPTY WEIGHT 314000 (empty_weight in [WEIGHT_AND_BALANCE])
ZERO FUEL WEIGHT 413949 (PAYLOAD + ZERO FUEL WEIGHT)
FUEL WEIGHT 250000 (WEIGHT OF THE FUEL)
Here are the data needed to calculate the MAC%:
GROSS WEIGHT 663949 (WEIGHT OF AIRCRAFT BEFORE TAXIING)
TOTAL MOMENT -3315313.5 (MOMEMENT)
AFT MAC LIMIT 42.0 (wing_root_chord in [airplane_geometry])
FWD MAC LIMIT ??.?? (DO NOT KNOW WHERE THIS IS YET ???)
During a search I discovered this Take-Off & Landing Performance Calculation Tool: TopCat. TOPCAT Home page. It calculates the MAC% for you.
That's why they pay dispatchers to do this stuff! :D
All you need to know is the %MAC from the dispatcher and look up the TO trim setting.
Hi to all,
I can tell you how I procced with this problem.
1.) I start at parking position, with changing the payload and the fuel load depending the flight I want.
2.) I configure the flight route to FMC.
3.) At init ref page I inform the weights.
4.) The CG% is always 22 at me. I press the LSK to be reseted and I have only the squares.
5.) I open pmcheckfile and I type the offset 2EF8 8 getting the CG%.
6.) I enter the valve to pm cg% and I get the trim which I configure to aircraft.
With this way, I always can rotare the plane at VRotate speed and not before or after.
* I will build a small program today or later tommorow to read the aircraft weights, the CG% and the trim value. It will be for free. So it will really easy to run this proggram and get the values you want.:wink:
Achilles,
thks for that one. That is a great solution. :)
At least I had lots of fun learning about the MAC% calculations. At least now I can calculate the missing FWD MAC LIMIT if the AFT MAC LIMIT is indeed the same as the wing_root_chord in [airplane_geometry].
Maybe TasKing or you can write a Gauge to show the CG%? That will be really cheating. No dispatchers needed thank you. ;)
Ok,
I uploaded a program I made. It is calling payload manager.
Works via fsuipc and wideclient. Reads the data from Fs and also the CG%.
http://www.mycockpit.org/forums/down...do=file&id=310
Options
Aircraft type
Flight number
Tail number
Airline name
Max Gross weight
Basic operating weight
Payload
Zero fuel load
Fuel weight
Total weight
CG%
CG% Fwd
CG$ Aft
Trim indicator as value.
Overload Warning.
If someone have any new ideas to add to this program just post it.
Thanks, any chance to use it with KG ?
Kg.....? what's that...(lol)