Hi,

my aircraft is always empty......no passenger on board.......and I tell you why! I don`t know how to find out the Center of Gravity. I allways take something between 20-25. Where will I find this data?

After takeoff and switching on the autopilot everything is fine....but before... oh,oh,oh......this is the time where my crew has to assuage the screaming and crying passengers, telling them......yes, we can make it..... we will reach safely our destination. Less and less passengers
are booking my flights. I guess your cabin is always fully booked. :-)

Please, please help!!! Otherwise my airline is next week bankrupt. And I don`t know if the crew can reassure in these days the bank.

Your help is needed now.

Thank you!

Regards,

Fabian

I don't know how to figure the Center of Gravity, but I always use 30% regardless of payload and it does just fine. One thing to take not of is that if I have full fuel tanks, I leave the trim at the setting it is at when the 767 first loads. If I have a 50% or less fuel, I put the trim setting at 3. That's the reading on the VC pedestal and not the Cockpit Tooltips info when you mouse over the Trim Wheel.

After takeoff and switching on the autopilot everything is fine....but before... oh,oh,oh......this is the time where my crew has to assuage the screaming and crying passengers, telling them......yes, we can make it..... we will reach safely our destination.
What is actually happening with the 767? I can't quite figure what you mean by that. :(

Mark

Hi Mark,

thanks for your quick reply. After taking off, I have realy problems to fly the 767 stabil and horizontal. I have to press the yoke down otherwise
the aircraft would go up and down. How can I stop this.  I can`t find out how to fly the 767 smoothly after getting airbourne.

When I have reached 2000-3000 feet, I activate the autopilot. The rocking stopps and the aircraft is flying normaly.

Is there anything I´m doing wrong?

Please help.

Thank you!

Fabian

Hey guy's,

I was having the trim problem and used a formula that was somewhere in this forum...FMC tutorial I think. (I want to say that this was in addition to the original post which was very helpful) but this didn't seem to work, after engaging LNAV/VNAV approx. 400ft AGL aircraft would pull up into a stall or etc....yeah, not right.  

I'm not looking at my 767 FMC right now but there is a figure that is there on the page before you enter CoG. I remember it being in the bottom right, and it's a percentage.

Without looking into the manual to find out what it said about that number I entered it as CoG and got good results...smooth takeoffs.

I will go look eventually but does anyone know about this?

Quote:

I'm not looking at my 767 FMC right now but there is a figure that is there on the page before you enter CoG. I remember it being in the bottom right, and it's a percentage.

I think you are talking about the PERF INIT page of the FMC. It always gives me a figure of 25%.
I do not recall seeing any other number in there than that regardless of my payload settings.

Mark

Hi Mark,

hopefully you can help? For example this is my flight. FSIA to FIMP.

PERF INIT                                                CRZ alt FL330
GR WT                                                     Cost Index 80
307,50                                                     CRZ   CG

Fuel                                                          25      0%
42,6 lbs calc.

Reserves
7,5

TAKEOFF REF

Flaps                                                               Ref V1 134
15/1000FT                                                       Ref VR 139

Thrust 30                                                         Ref V2 147
Trim 2.98    C.G 25%

After taking off, the nose is coming up to quickly and I have to press the yoke down to fly the 767 stabil and horizontal. Do I do anything wrong?

Thanks for your help!

Regards

Fabian

When trimming the aircraft, do you trim it to 2.98 (3) going by the information displayed using Cockpit Tooltips? Or by the Stab Trim Indicator (see attached image)?

I use the Stab Trim Indicator and if I place it below 3, the nose barely rises and I need to apply more force to get it off the ground. If my aircraft is at about 330,000 pounds or less I use 3, above that and I use 4 or the default setting. That usually gets me off the ground nicely.

Prior to takeoff, I turn on the VNAV (LNAV only gets turned on the if the SID is straight ahead). Once above 200 feet AGL, I urn the A/P on (I use the center CMD switch most of the time).

In reality, it sounds like you are tail heavy. This is where the CG according to the FMC or just trying to figure it out using the diagram in Aircraft > Fuel and Payload, comes to grief.

Mark

---

Hi Mark,

sorry for bothering you again. I have still some questions left. In my flight example the aircraft weight is less than 330,000 pounds. I use 3 and the nose rises very fast. Why?

From now I will use the Stab Trim Indicator. Everything higher 330.000
pounds requires 4 or more. I guess the Trim Indicator will show me this correctly.

What is the default setting? When do I use this?

I now what Trim means. What does C.G means? What is the context of both?

What would be the Trim and C.G in my case? (Flight FSIA-FIMP)

Thank you for your help!

Fabian

Hi Fabian

What is the default setting? When do I use this?
The default setting is 4 on Stab Trim Indicator or 0.0 with the mouse over when displaying Cockpit Tooltips.

http://i669.photobucket.com/albums/vv58/Markoz958/767trim.jpg
Notice that the white bar ends at #4 and my Cockpit Tooltip displays 0.0

Make sure that on your default flight (FSX - Free Flight) has it's trim set to 0.0 according to the Cockpit Tooltip. I don't know if it does carry over to the 767 when loaded into FSX, but it is better to be sure in the first place.

CG/CoG is the Center of Gravity. The point where the amout of weight between the front and the back is equal. The best place for this is 1/3 the Wing Root Chord, this usually where the MAIN GEAR is located on an aircraft (Lou can correct me if I'm wrong ;)) AND It's not the same for a Tail Dragger. I don't fully understand how the numbers (25%, 27%, 30% etc.) work, but I do know that an aircraft has a limit or a range that it must keep within, otherwise it is nose or tail heavy.

In my flight example the aircraft weight is less than 330,000 pounds. I use 3 and the nose rises very fast. Why?

Your setting is the same as I would use for the Stab Trim Indicator but certainly not the Cockpit Tooltip. If you are using 3.0 on the Cockpit Tooltip reading, this would explain your problem. If I use the Cockpit Tooltip reading, the Stab Trim Indicator is at 6. I do not go above 4 or below 2 on the Stab Trim Indicator (well not since I learned how it works ;D).

Hope this helps

Mark