Grossly Overweight Project Airbus Offerings In FS2004.

I recently began to use the Project Airbus A380-800 freeware aircraft and have noticed that the default Fuel and Payload figures I was presented with were WAY over MTOW to the avail of some 156,000 lbs! The only way to reduce these to an acceptably safe MTOW is to alter them manually and should a full quantity of fuel be required Payload has to come down to below 10,750 lbs. This is hardly realistic but is required as I have attempted to fly the PA A380 when 62,000 lbs over MTOW and could not stabilize the aircraft upon reaching loiter height. Instead of holding a steady FL 290 the aircraft flew a wierd phugoid-type pattern +/- 200 feet of FL 290 which for any occupants on board would have rapidly filled their sickbags!

I am used to their Airbus Narrowbody offerings having overweight default Fuel and Payload figures however I often find that loading an 80% fuel quantity often coupled with an 80% to 85% Payload load factor fixes this and both of these are realistic. However to get the Airbus A321-200 to climb any faster than 1,500 FPM to 12,500 feet and 1,000 FPM to loiter height (suggest FL 280 / 290 for realism) without stalling requires a 65% to 70% Payload load factor. Who else is discovering what I have found with Project Airbus's otherwise excellent offerings in FS2004?

How are these problems corrected please so that the default weight and balance starts off within MTOW limitations and does not require such extensive alteration before every flight?

Many Thanks.

Hi,

I'll try to answer your question, but keep in mind some of this is personal choice. The way it is set from the authors is a perfectly valid way to set up an aircraft - it just requires you to set the payload and fuel manually each time before you fly.

If you want a setup that is less work (and follows way the majority of aircraft authors set up their weight and fuel), that would be to set the default payload so the plane is at MTOW when at 100% fuel.

Let's start by looking at the plane's aircraft.cfg file. I'm using the Farnborough A-380-841 in the folder of the same type name, since I only have generic information available to me.

In that cfg file, you will find this section:

[weight_and_balance]

empty_weight = 611000.00

max_gross_weight = 1124400.00

reference_datum_position = 0.00, 0.00, 0.00

empty_weight_CG_position = 12.50, 0.00, 0.00

empty_weight_pitch_MOI = 42600000.00

empty_weight_roll_MOI = 22350000.00

empty_weight_yaw_MOI = 49400000.00

empty_weight_coupled_MOI = 0.00

max_number_of_stations = 9

//A380-842 config (R12 J60 Y399 TOTAL471)

//Pax Zonings

station_load.0 = "1950.00, 80.00, 0.000, 3.000, CAB LA R (12)" //2100lbs

station_load.1 = "20050.0, 37.50, 0.000, 3.000, CAB LB Y (126)" //22050lbs

station_load.2 = "14325.0, -8.00, 0.000, 3.000, CAB LC Y (91)" //15925lbs

station_load.3 = "15150.0, -43.00, 0.000, 3.000, CAB LD Y (94)" //16450lbs

station_load.4 = "10000.0, 30.00, 0.000, 11.00, CAB UA J (60)" //10500lbs

station_load.5 = "13250.0, -35.00, 0.000, 11.00, CAB UB Y (88)" //15400lbs

//Cargo & Baggage

station_load.6 = "19000.0, 63.00, 0.000, -4.000, CPT 1 (63000)" //Fore (63000lbs)

station_load.7 = "12000.0, -23.00, 0.000, -4.000, CPT 2 (44775)" //Aft (44775lbs)

station_load.8 = "1000.00, -45.00, 0.000, -3.000, CPT B (5540)" //Bulk (5540lbs)

Apparently PA had -842 data and that's what they used. That's fine. As you can see, it contains 6 passenger "zones" and 3 cargo zones.

The first 4 zones are in the lower level (3 feet above the center point), while the next 2 zones are in the upper level, 11 feet above the 0 point. The three cargo zones are below the floor, -4 and -3 feet below.

From this site:

https://aviation.stackexchange.com/questions/1008/what-is-the-weight-budget-of-a-fully-loaded-a380

and this one:

http://www.modernairliners.com/airbus-a380/airbus-a380-specs/

they say that the maximum payload is calculated by subtracting the the Operational empty weight (277,000 kg) from the Zero fuel weight (361,000 kg). This means the payload weight is about 84,000 kg. This converts to 185,188 pounds.

The passenger and crew weight can be estimated by the following numbers:

175 lbs per pax + 30 lbs of baggage for short medium range distance (or 40 lbs for long range)

175 lbs per crew member + 30 lbs of baggage

Since this is a long range aircraft we'll use 40 lbs of baggage.

The aircraft.cfg file listed above already shows that this plane can carry:

//A380-842 config (R12 J60 Y399 TOTAL471)

so 471 x 175 lbs = 82,485 lbs of passengers, and 18,840 lbs of baggage. That's a total of 101,325 lbs. That means we have room for 185,188 - 101,325 = 83,863 lbs of cargo. So 82,485 lbs can go above the floor, and 83,863 + 18,840 = 102,703 lbs can go below the floor.

The current payload settings in the cfg file are 74,725 lbs above the floor and 32,000 lbs below the floor. Their max values (in parentheses) are 82,425 lbs above the floor and 113,315 lbs below the floor. So the passenger weight is exactly the same as my calculation, and the cargo/baggage weight is pretty close, they have it set a little higher than my source's value.

When we check the Operational Empty weight in the cfg file (empty_weight), it matches almost exactly with my source. However, the MTOW (max_gross_weight) is not even close. That is listed in my source as 1, 234,600 lbs, while the cfg file value is only 1,124,400 lbs. I see values in the literature that vary from 1,200,000 to 1,267,658 lbs, so my source's value is probably OK. This difference in the FS MTOW is probably the source of the small payload with full fuel! So let's change that to the correct value:

max_gross_weight = 1234600.00

Now all we have to do now is to lower the payload value so we are not over the max takeoff weight with full fuel.

Our sources above say that we should be able to load 320,000 liters of fuel, which is 84535 gallons. The values in the cfg file are in this section:

[fuel]

fuel_type = 2

number_of_tank_selectors = 4

electric_pump = 0

Lefttip = -25.00, -100.00, 2.00, 2731.54, 0.00

LeftAux = 3.00, -55.00, 1.00, 16931.58, 0.00

LeftMain = 25.00, -20.00, 0.00, 19942.61, 0.00

Center3 = -85.00, 0.00, 8.00, 6260.35, 0.00

RightMain = 25.00, 20.00, 0.00, 19942.61, 0.00

RightAux = 3.00, 55.00, 1.00, 16931.58, 0.00

Righttip = -25.00, 100.00, 2.00, 2731.54, 0.00

and add up to 85,471.81 gallons. That's a little more than my source, but perhaps they have a more accurate value. But it's close in any case, and we'll use it.

The weight of that fuel in FS at 6.7 lbs/gallon is 572,661.12 lbs. So, first if we load the full fuel load and add it to the empty weight value from the cfg file, that's the weight of everything but the payload. And then second when we subtract that calculated value from the MTOW we get our allowable payload when at 100% fuel to remain under the MTOW.

So:

Empty Weight + Fuel Load = 611000.00 + 572,661.12 = 1,183,661.1 lbs.

MTOW - that value is 1,234,600 - 1,183,661.1 = 50,938.9 lbs

This is our allowable payload with full fuel, so we need to reduce the station loads in the Weight and Balance cfg file section listed above down to that number. Assuming that they have calculated the balance of the plane correctly with their current station loads, what we can do is reduce our values by a set percentage value and so keep the balance the same.

Since the current payload is 74,725 + 32,000 = 106,725 and we need it to be 50,938.9, if we divide one by the other we get 50,938.9 / 106,725 = 0.477291, a little less than half the current payload (and somewhat less than that for the maximum payload allowed).

So multiplying all the station load weight values by that percentage gives:

//Pax Zonings

station_load.0 = "931.00, 80.00, 0.000, 3.000, CAB LA R (12)" //2100lbs

station_load.1 = "9570.0, 37.50, 0.000, 3.000, CAB LB Y (126)" //22050lbs

station_load.2 = "6837.0, -8.00, 0.000, 3.000, CAB LC Y (91)" //15925lbs

station_load.3 = "7231.0, -43.00, 0.000, 3.000, CAB LD Y (94)" //16450lbs

station_load.4 = "4773.0, 30.00, 0.000, 11.00, CAB UA J (60)" //10500lbs

station_load.5 = "6324.0, -35.00, 0.000, 11.00, CAB UB Y (88)" //15400lbs

//Cargo & Baggage

station_load.6 = "9069.0, 63.00, 0.000, -4.000, CPT 1 (63000)" //Fore (63000lbs)

station_load.7 = "5727.0, -23.00, 0.000, -4.000, CPT 2 (44775)" //Aft (44775lbs)

station_load.8 = "477.00, -45.00, 0.000, -3.000, CPT B (5540)" //Bulk (5540lbs)

and with the edited MTOW value gives us exactly MTOW at full fuel.

Hope this helps,

Tom, Hi and I hope you are well.

MASSIVE thank you for your response which I have found very useful. I have learned tons from this as no doubt will others who read all this too. I agree with you about the elements of personal choice too and on reflection I think I much prefer to have the choice not the restriction over this one. Even if it does entail setting each and every aircraft up prior to usage an an appropriately safe condition. Each flight thinks me is a unique event and this is something which brings that across effectively.

Thanks Again!