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 10 757 weight & balance / payload "guide" (Read 21003 times)
fowler
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757 weight & balance / payload "guide"
Oct 20th, 2015 at 10:19pm
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Guys, all these years with this lovely B757 and I just now quite figured it out : I became tired of beeing able to load the aircraft via ACE putting full pax and full cargo and still beeing able to have almost full tanks and still within limit of the MTOW. I just knew this is not real as all aircrafts have limitation between either full payload / full fuel. (heck even a Piper PA-28 Archer has such limations) So I did some research over the internet and I found out that the ACE is not doing a good job at computing the max payload for this aicraft (not at the defaut unit weight of the cargo container "ULD" found in the ACE) But the good news is that this default unit weight can be modified be the user. So I made a "guide" with various figures for the 2 main scenarios I'm mostly interested when I fly : a) fly at full fuel and max payload b) fly at full payload and max fuel. The part that needed research over the internet was the full payload figure, and I found them for all variants in several Boeing documents. The full payload added the the empty weight gives you the MZFW, which is the figure I found in the Boeing documents. SO here we go...
  
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fowler
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Re: 757 weight & balance / payload "guide"
Reply #1 - Oct 20th, 2015 at 10:24pm
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B757-200 :

Weights in pounds

Maximum Taxi Weight (MTW)                256'000
Maximum Take Off Weight (MTOW)       255'000
Maximum Landing Weight (MLW)           210'000
Maximum Zero Fuel Weight (MZFW)      186'000
Empty weight :                                    130'875
Max fuel :                                             75'502 -> MAX PAYLOAD 49'623 : FULL PAX selon ACE avec 9xULD à 2'647 / équipage à 0)
Max payload weight :                      55'125 -> FULL PAX selon ACE avec 9xULD à 3'258 avec 1 ULD à 3'261 / équipage à 0)
Max fuel @ max payload :                  70'000 -> 93% sur les 3 réservoirs et réduire le central à 42'883)
  
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Re: 757 weight & balance / payload "guide"
Reply #2 - Oct 20th, 2015 at 10:25pm
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B757F CARGO :

Weights in pounds

Maximum Taxi Weight (MTW)                256,000
Maximum Take Off Weight (MTOW)           255,000
Maximum Landing Weight (MLW)             210,000
Maximum Zero Fuel Weight (MZFW)          200,000
Empty weight :                           114'000
Max fuel :                                75'502 -> MAX PAYLOAD 66'498 : 15xULD main deck à 2'955 + 15xULD lower deck à 1'477 avec 1 ULD lower deck à 1'495 / équipage à 0
Max payload weight :                      86'000 -> 15xULD main deck à 3'822 + 15xULD lower deck à 1'911 avec 1 ULD lower deck à 1'916 / équipage à 0
Max fuel @ max payload :                  56'000 -> 74% sur les 3 réservoirs et mettre le central à 34'422)
  
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Re: 757 weight & balance / payload "guide"
Reply #3 - Oct 20th, 2015 at 10:25pm
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B757-300 :

Weights in pounds

Maximum Taxi Weight (MTW)                271,000
Maximum Take Off Weight (MTOW)           270,000 (also max FMS)
Maximum Landing Weight (MLW)             224,000
Maximum Zero Fuel Weight (MZFW)          210,000
Empty weight :                           142'350
Max fuel :                                75'502 -> MAX PAYLOAD 53'148 : FULL PAX selon ACE avec 9xULD à 2'305 avec 1 ULD à 2'608 / équipage à 0)
Max payload weight :                      67'650 -> FULL PAX selon ACE avec 9xULD à 3'916 avec 1 ULD à 4'222 / équipage à 0)
Max fuel @ max payload :                  61'000 -> 81% sur les 3 réservoirs et réduire le central à 37'382)
  
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Re: 757 weight & balance / payload "guide"
Reply #4 - Oct 20th, 2015 at 10:34pm
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Quick notes : you need to use the ACE for loading whatever payload you want (you can also edit in FSX but I find it less easy/practical) and then use FSX for adjusting the fuel load. So for each of the 757 variants above you will find the last three lines of each block :
a)Full fuel and max payload
b)Full payload
c)Max fuel at full payload

right from these lines you will find what are the figures to use in ACE to come directly to these figures, and also how to fill the tanks in FSX to come directly to the MTOW without too much tweaking... 

I hope you find it usefull. Notice the differences between the 3 models, in particular empty weights and corresponding MZFW...

PS : I will post the same info for the 767 in the 767 thread.
  
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Re: 757 weight & balance / payload "guide"
Reply #5 - Oct 20th, 2015 at 10:36pm
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PS 2 : For full fuel scenarios and the figures I quoted are with 100% for each wing tank and 99.9% for center tank. For a reason I don't know FSX doesn't let you enter 100% for all the tanks. Difference is negligible/minimal
  
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Re: 757 weight & balance / payload "guide"
Reply #6 - Oct 20th, 2015 at 10:44pm
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PS 3 : Just a hint : when you load with ACE then save, then open your 757 aircraft in FSX to adjust whatever fuel you want, if you check the payload tab (fuel and payload menu), you would see that there is a slighly different total weight than what ACE was giving you, and this is because the pilots and attendants weights were added. I always remove all these weight as they belong in fact in the Operating Empty Weight of the aircraft (surely not Payload  Grin) For simplifications I would consider empty weight and operating empty weight similar.
  
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Re: 757 weight & balance / payload "guide"
Reply #7 - Oct 21st, 2015 at 5:58pm
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PS4 for the 757F cargo : when you load via the ACE the unit weight for each lower deck container and main deck container and then load your 757F, then load in "real time" the 15 lower deck containers and 15 main deck containers (is fun one time only) then save to reinitialise your flight with the new load, and if you check your aircraft fuel & payload figures, you will see your payload is a lot short of the ACE figure, this is because the ACE is missing 2 main deck containers entries. I counted only 13 entries instead of 15 loaded, probably a bug. So this is why I use a plugin weight that I enter in FSX to come up the the correct max payload. (see the details in the 757F block)

Also when changing from flight assignements (full fuel flight and then max payload for instance) instead of having to unload "live" all containers, change the unit weight in ACE then reload them again, you can leave them all boarded, change the new value of each unit in ACE, load your aircraft, open the "live" loading menu/icon then without changing anything just press "save" to reinitialise your flight with the new payload you want. /which will be based on the number of containers boarded x unit weight as found in the ACE)
  
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Re: 757 weight & balance / payload "guide"
Reply #8 - Oct 22nd, 2015 at 11:06am
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Thank you for your input!
  
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SEAN ZARELLA
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Re: 757 weight & balance / payload "guide"
Reply #9 - Oct 26th, 2015 at 6:43pm
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Ok so first of all, You have to realise that Captain sim. other, Ect never assign payload along the longtitudinal axis of the plane there fore assigning all the weight at station 0.0  thus giving an incorrect empty weight CG% and the empty weight is incorrect

What MSFS does is go by OEW or operating empty weight,

but it is incorrect.

Another thing is that CS .air file shows static thrust closer to the rating of PW2040 Engines rather than 2037 engines increasing its range, MTOW  and MLW. 

in the .air file shows 40177 lbs of static thrust
the PW2040 is 40100 Lbs  instead of 36600 of the PW2037 that shows in the FMC, so this changes and if you see this from boeing youll see the change in MTOW and MLW

Engines```````````````````      Thrust
Pratt & Whitney PW2037      36600 lb st (162.8 kN)
Pratt & Whitney PW2040      40100 lb st (178.4 kN)
Rolls Royce RB211-535C      37400 lb st (166.0 kN)
Rolls Royce RB211-535E4      40200 lb st (178.8 kN)
Rolls Royce RB211-535E4-B      43500 lb st (193.5 kN)
Fuel capacity      42684 liters (11276 US gallons)

and you know what that means??

operating weight empty----      57840 - 57075 kg (passenger version) / 50475 - 50605 kg (freighter)
freighter revenue load-----      32755 kg (72,212 lb)
freighter payload 757-200 SF----      27215 kg (59,998 lb)
max take-off weight (PW2037 & RB211-535E4)      99790 kg (220,000 lb
max take-off weight (PW2040 & RB211-535E4--B)      115665 kg (255,000 lb)
max landing weight (PW2037 & RB211-535E4)      89815 kg (198,000 lb)
max landing weight (PW2040 & RB211-535E4-B)      95255 kg (210,000 lb)
max ramp weight (PW2037 & RB211-535E4)      100245 kg (221,000 lb)
max ramp weight (PW2040 & RB211-535E4-B      116120 kg (256,000 lb)

So this means that our CS757  with PW2040 engines have a new MTOW of 255,000 Lbs and MLW of 210,000 Lbs.

Now that we know that Here is how we calculate CG%
Before we Begin, These are some specifications we must know before we begin, involving the Boeing 757-200

Empty Weight: 125,750 lbs // Weight of the aircraft empty without any fuel, Passengers, crew, catering, and cargo.

Dry Operating Weight: 130,875 lbs // Weight of aircraft with Crew, Crew bags, Unusable fuel, Galley Equipment.

Zero Fuel Weight: -------- // Weight of aircraft with crew, passengers, and cargo. Without Fuel.

I will start with the basics on the fundamentals before I go into the actual math involved in determining your planes CG% or %mach can also be called.

All Center of gravity is based upon the starting point which we call DATUM.

DATUM is referred as the starting point of the line which the manufacturer determines for each plane they make, and for the B752 that line starts 159 inches in front of the nose.

You draw that line linear from that point to the start of a small window of balance which we call MAC. which is mostly located at the wings ( center Of plane)

Here is an illustration



So you start with your Datum and a line is drawn from there to the start of the MAC and measure that distance in inches. , the start of the MAC line we call LEMAC or leading edge MAC.

and for the B752 LEMAC is @ 991.9 inches from the datum. The mac line starts from there and is 199.7 inches long,. we refer MAC as 199.7 inches.

So drawing that line from Datum to the LEMAC point and if you add up the point of LEMAC 991.9 + your mac 199.7 = 1191.6

0% mac is 991.9 inches. where it starts, 100% mac is 1191.6 inches.

Here is a image of what we are talking about, I illustrated where the datum line starts and where lemac is and 0 - 100 % MAC.



Between 0%MAC and 100% MAC is the window of CG we need the plane to be balanced. But that isn't the balance point. Per aircraft each is different based on Weight and

placement of Objects forward and aft of the LEMAC line. For instance, For the B752 The CG window envelope is 7% - 39% CG and that depends on your Gross Weight.

This can be found in the 757 - 200 weight and balance handbook.

Finally, where the Cg is located within that window is called BALANCE ARM or the distance from CG% to datum. measured in inches.

ARM is measured by balance point when the airplane is at DRY OPERATIING WEIGHT or EMPTY WEIGHT, and changes from aircraft to aircraft because of seating configurations

forward and Aft Lemac. I found out that per the 757-200 Delta Flies is called. DAL 75X PER delta seating specification that can hold 184 PAX.

The Balance Arm or distance from datum to the EMPTY WEIGHT CG is 1037.8 inches. This is How you determine your planes EMPTY CG%

````````````distance aft of LEMAC
`` cg%mac = ___________________
```````````````````` MAC


Distance aft OF LEMAC is easy to figure out now, if our LEMAC is 991.9 inches and the balance arm is 1038.7 inches. we take 1038.7 -991.9 = 46.8 inches.

````````46.8
CG%=____________ = 23.43%
```````1.997

if you just had your CG% and needed your ARM ( to compute DOI )

~~~~~~~~~~~~~~~~~~%MAC
Balance Arm = LEMAC + ( ----------------× MAC )
~~~~~~~~~~~~~~~~~~ 100

SO

``````````````` 23.43%
ARM = 991.7 + ( ----------------- x MAC ) = 1038.68971 or 1038.7
`````````````````100

Next is Computing the planes Dry Operating Index empty weight.

Formula for this is for the B752 for its BASE DOI before LMC

DOI = Weight x (Arm - 1037.8) + 50
````````````````75000

Since balance arm base before LMC is 1037.8. that zeros out the equation and you add 50. so our DOI is 50.

refer to the actual LOAD SHEET to find CG% and Trim values.



Now that we Know how to compute CG% and Trim. Follow the instructions below to edit your plane to match Deltas, 75X 184 pax.








I have discovered that The planes OEW CG% is 23.47% and 130875 LBS.

In order in MSFS to match this was to navigate to my Aircraft.cfg and change the following

[WEIGHT_AND_BALANCE]
max_gross_weight = 256000 // (pounds)
empty_weight = 127520 // (pounds)
reference_datum_position = 2.3, 0, 0 // (feet) distance from FlightSim Reference position: (1/4 chord, centerline, waterline)
empty_weight_CG_position = 2.5,[/color][/color][/color][/color] 0, 0 // (feet) longitudinal, lateral, vertical distance from specified datum

max_number_of_stations =12

station_load.0 ="460, 70, 0, 0, Flight Crew"
station_load.1 ="920, 0, 0, 0, Cabin Crew"
;Moments of Inertia
empty_weight_pitch_MOI = 7040000
empty_weight_roll_MOI = 1960000
empty_weight_yaw_MOI = 7500000
empty_weight_coupled_MOI = 1000
station_load.2=5970, 25, 1, 0, F/C Row 1-7
station_load.3=15612, 14, 1, 0, E/C ECON Row 20-30
station_load.4=12398, -13, 0, 0, ECON Row 31-39
station_load.5=8265, -33, 0, 0, ECON Row 40-45
station_load.6=888, 25, -1, -2, FWD Cargo Bay 1
station_load.7=0, 12, -1, -2, FWD Cargo Bay 2
station_load.8=8312, -12, -1, -2, AFT Cargo Bay 3
station_load.9=0, -25, -1, -2, AFT Cargo Bay 4
station_load.10=1975, 0, 0, 0, OPERATIONAL ITEMS
station_load.11=0, 0, 0, 0, ADDITIONAL WEIGHT


This load station data will give you a fully loaded 757 X version of 184 passengers, and 9200lbs cargo. and a ZFW of 182,320 LBS

This station load data also Matches Simbrief.com for all your planning needs. And this is how these numbers came from.

Simbrief uses 229.59 per passenger/with baggage, per each row. and section. for instance we get this weights from how many pax in a row and section,

first class holds 26 pax, so 26 x 229.59 = 5969

so you see where i am getting the station load data from. 26 first class 68 is economy comfort with a few rows of economy 54 is economy and 36 per last row of economy,

So this accounts with simbrief without adding cargo. just 184 pax. we still have to add 50 lbs per pax per baggage thats checked in. x 184 = 9200lbs.

The Above Configuration will give your 757-200 an accurate weight of ZFW of 182,320 lbs @ 29% CG

To match Simbrief you will need to edit your 757. Follow below.

Max Passengers: 184
OEW (Empty Weight):130.8      (in thousands of pounds)
MZFW (Max Zero Fuel Weight):184.0      (in thousands of pounds)
MTOW (Max Takeoff Weight):240.0      (in thousands of pounds)
MLW (Max Landing Weight):      198.0 (in thousands of pounds)
Max Fuel Capacity:75.6      (in thousands of pounds)



When you are plotting your dispatch on Simbrief, Select Passengers to FULL, Cargo to 9200 and ZFW to AUTO

Your plane will always come out to 182,320 LBS as designed to match your loaded 757-200.



I know this has been long and exhausting but I Know all there is to CG% and load balance data on this bird Smiley

Any questions let me know

here is the real Load balance sheet for the PW2040 757-200




What I do , belonging to Delta Virtual Airlines, Is we have an acars program for dispatch and flight tracking, I manually set my flights through the aircraft.CFG and always have a full flight  with 184 pax, and 50lbs bags per pax 9200lbs,
  
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fowler
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Re: 757 weight & balance / payload "guide"
Reply #10 - Oct 31st, 2015 at 2:21am
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Hi Sean, very good info there...  I still have to go/read all of this data you put here, but it triggers the question IMHO as how detailed and exact you want to use / hope to use FSX for simming. For me it's OK even if the trust figures, engine model, CG calc. (as long as it does not impact the flying model) etc... lack 100% accuracy. Doesn't spoil my fun as much as the ability to fill the tanks and load almost 100% payload trough ACE as I know THIS is FAR from reality. Now this was bugging me, and so I made the tables above when I relaised the ACE did not a good job at load calcs. It is meant to at least let you load you aircraft to the max payload as found in the general Boeing docs and see how far you could go... anyway thanks for your info.
  
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SEAN ZARELLA
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Re: 757 weight & balance / payload "guide"
Reply #11 - Nov 4th, 2015 at 6:32pm
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Oh no problem bud, Your information is key as well. With different models. 

Since I fly for a Delta VA,  i Picked the Delta 75x and know how to set it up to a real life 75x  With station load data, empty weight CG% and Operating empty weight. So when I load my plane, I always can figure out  the new CG% and trim.  that most pilots guess the trim value as long as it lifts, Im a hardcore pilot with actual load and balance sheets.
  
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Re: 757 weight & balance / payload "guide"
Reply #12 - Nov 10th, 2015 at 10:57pm
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Hi Sean, yes it is impressive how far you can go with this simulation. I'm impressed by your dedication to it. Regards
  
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SEAN ZARELLA
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Re: 757 weight & balance / payload "guide"
Reply #13 - Nov 12th, 2015 at 2:55am
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Thank you sir,   My obsession carried me to this.



  
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