Calculations, Autoflight, and Fuel Frenzy

[Aiden327]

Well for Christmas, I used some of my money to purchase a Captain Sim 757. I have been reading about it for a year, and the 757 has become the ideal plane for me for short flights, balance of new and old, almost completed simulated, and a challange.

I don't know if anyone is able to help me with all these problems, but the captainsim forum is full of complaints and most of the answers are "you did it wrong" or "download this random spreadsheet to solve your problems" so I thought I woud ask here before I post thier. Its kinda nice to not have the thread spammed by people saying its a bug in the software and they don't actually want to learn to fly the plane

[BSW727]

The performance data is incomplete. There is not enough information provided to know where the %MAC is to set the units of trim.

Captain Sim strikes AGAIN! 

[Aiden327]

If you enter a CG value it does display takeoff trim. 24 works fine but I wish I could fine tune it to match.

I had a right engine fail for no reason when increasing power after pushback. I wonder if I binded a key or something that is messing with it. Might me my mixture on the rotary. Hmm......

[BSW727]

How do you know if that CG value is any good?

[Aiden327]

That is my point

[BSW727]

"I will start with the easiest problem. The FMC "requires" the aircraft center of gravity. Nasa's equations is beyond calculus. All the calculators I find online, need the reference bars and reference bar length as well as the the aircraft dimensions. This is beyond my knowledge as its supposed to be done for the pilot on the load sheet"

This is why the data CS provides is incomplete. Because it is a model, the coding should include the percent of mean aerodynamic chord depending on how you load the aircraft. It's nearly impossible to calculate %MAC without knowing which station aft of the datum plane it's calculated from, the arm and moment length, and weight distribution.

The numbers CS provides are meaningless. It's a crapshoot for whatever you dial in for a trim unit, and that will again vary with a TO flap setting and ambient air temp.

Try this: The 757 and 727 are nearly the same size, and the 757 has a few thousand pounds on the 727. At a takeoff weight of, say, 170,000 lbs roll in 5.8 units of trim and use a V1/VR of 135 KIAS and a V2 of 143 KIAS at 15

[Aiden327]

My gross weight with cargo was 175.1 so I entered that, 15 degrees of flaps. In order to move on, I had to put in a CG value so I noticed on the ref page it had 27 for cruise CG so I copied that to the takeoff CG and it gave me my speeds. V1 is 128, VR 134, and V2 was about 147. So it very close to what you have. Takeoff trim was around 4.48 as well.

I have found a website that can produce a load sheet and fuel sheet for a 757 (still no cg value) and this is the flight I fly now.

I fly a real route I found on flight aware with flightplan. Its UPS 7472 from KDCA to KIND. I put in the info and it spits out this.

[code][FUELPLAN