Jump to content

Center of Gravity / Pitch Trim || Manual input values


Wolf0

Recommended Posts

Hello.

I'd like to start by saying that I'm aware that there is an open issue with the pitch trim not being set by the "copilot" on V1.31 and this topic is not about that. That feature doesn't affect me, since I've always flown with the virtual first officer disabled, and never used the fuel planner / load manager provided by Aerosoft. My load and balance sheets are made via Topcat for the A320-214 with data from PFPX.

With this setup when I start a flight I have a known value of Fuel, Passengers (with respective standard weights) and Cargo to load via the right MCDU. I also have a particular Center of Gravity given by Topcat determined by the cargo/passenger distribution aboard. With the previous versions of the Airbus, there was a field on MCDU2 where you could enter a value for the CoG. With the current version V1.31 the CoG value is modifiable like before, but there is no way to change the Pitch Trim that now appears next to it (0.8UP). Is that a bug? There should not even be the need to enter the Trim value, since it is a direct consequence of the CoG... so either the value changes automatically regarding the inputed CoG or the airplane is now always requiring a 0.8UP trim for departure...

Either way, that's not working for me, since I use independent software for my load and balance calculations. I just need to force the values I want to be uplifted aboard directly on MCDU2, instead of having to use the simpler loadsheet import function (that I've never used or intended to use).

Can someone from the developer team please shed some light on why was the value of the Pitch Trim added to the CoG load function on V1.31? What was the idea? To input both values? If so, there is a bug since the second field is not modifiable. Or was the Pitch trim supposed to be displayed according to the CoG selected for information purposes? If so there is also a bug, since the field always shows 0.8UP. And I want to be able to load tail heavy planes with departure trims of 0.5DN, for instance...

Link to comment
Share on other sites

  • Deputy Sheriffs

Hi,

I think you mixed up something. Those values in the MCDU2 are only for information and display the values from the LOAD and Fuel PLANNER. There are some bugs in it and we are working on it. But again those values are not used in any way to set pitch trim. The relevant value used by the Copilot is currently the one from the MCDU PERF TO page which currently is set to a standard value UP0.8. So if you use the CoPilot then you have to enter the relevant value in this field. If you do not use this function then you have to set the pritch trim yourself (ECAM FCTL page and using the trim wheel). I hope this ansers your question.

Regards,

Hanse

Link to comment
Share on other sites

54 minutes ago, Hanse said:

But again those values are not used in any way to set pitch trim.

can I just clarify your advice .....

i've assumed / understood the load / fuel planner is the only way to adjust the load distribution (& hence trim) and that is what one inputs in the PERF Page (after initiate loadsheet) ........& that editing / manually inputting a CG / Trim in MCDU2 does not distribute the load to match it ??

john 

Link to comment
Share on other sites

Ok. Thanks for the answer, Hanse.

I always thought that you could set the load distribution via the CG field on the MCDU2.

Can you please  confirm that you have to use the external fuel/load manager to force the required departure trim? 

If that's the case I'd like to request the development of the possibility to perform the load distribution via the MCDU2 CG field. For me and the other users that have PFPX/Topcat it doesn't make sense to use the Aerosoft external load manager. It's a duplication of preflight work and with much less features than we already have...

Link to comment
Share on other sites

  • Deputy Sheriffs

Hi,

sorry I do not agree. The pitch trim in any case to be set manually and the relevant value field is the MCDU PERF TO page (or use the CoPilot).who also uses this fielöd. If you are using a different program for the calculation then just forget those values in the MCDU2 LOAD FUEL menu....The only possibility I can think of is that (if the bugs are removed) that we align those values with the Pitch Trim value of the MCDU PERF TO page.......

Regards,

Hanse.. 

Link to comment
Share on other sites

52 minutes ago, Hanse said:

Hi,

sorry I do not agree. The pitch trim in any case to be set manually and the relevant value field is the MCDU PERF TO page (or use the CoPilot).who also uses this fielöd. If you are using a different program for the calculation then just forget those values in the MCDU2 LOAD FUEL menu....The only possibility I can think of is that (if the bugs are removed) that we align those values with the Pitch Trim value of the MCDU PERF TO page.......

Regards,

Hanse.. 

Sorry, Hanse. You didn't understand what I was asking and how I operate my flights.

Let me try to explain better. I'm not asking for the Pitch Trim to be set via the MCDU2. I do that manually like you suggested, i.e., I spin the trim wheel next to the throttle levers to match the required value determined by the loadsheet. I don't want the Horizontal Tail Plane to move via the MCDU2!

My problem lies elsewhere. When I decide for a flight my PFPX/Topcat software gives me a determined amount of passengers/fuel/cargo, distributed along the airframe. On one day I will carry more passengers on the front, one another will be carrying more freight on the back cargo compartment. This leads to a different loadsheet. Sometimes the airplane will be nose heavy, other times tail heavy, just like in real life. Sometimes you carry more business passengers, sometimes more economy seats are filled.

With the current version of the Airbus (V1.31) I can load the simulator, open MCDU2 and tell the simulator what my airplane weights for this particular flight. That's done via the PAX/Cargo/Fuel inputs, and the load can be uplifted instantly or over a realistic time. And the airplane is indeed loaded. It gets heavier and you really need different Vspeeds and different engine power settings to get airborne. All of this is working beautifully.

What we are missing now is a way to tell the MCDU2 where the actual CG for the current flight is. In other words: when you input the weights, how is the cargo distributed along the airframe?

Apparently the Airbus will always distribute the cargo in such a way as to give a CG of 26%MAC, thus requiring 0.8UP trim to be set. That's not normal operations!

I always thought that the CG input field was there exactly for this problem. To force the load distribution of the designated values on the aircraft.cfg instantaneously. In such a way that the aircraft would then need a given setting of Pitch Trim (manually selected via the pitch trim wheel on the central pedestal like you suggested, or via the virtual first officer action - that I don't use). 

My understanding is that the fuel/load manager external software allows a different CG to be selected. And this is correct. When you do that, the software must be changing the load distribution "behind the scenes" to provide a nose/tail heavy airplane, as desired. But since I don't use the fuel/load manager like I've explained and Aerosoft (rightfully) provided an alternative means to load the aircraft via the MCDU2, there should also be a way to force a desired CG for the selected flight. And apparently there is not, according to your explanation.

That would be useful and logic to implement.

Link to comment
Share on other sites

  • Deputy Sheriffs

Based on the CG (displayed from hte Load/Fuel Planner or manually entered/modified) the cargo will be "distributed" to the plane..A cargo payload of 3.000 kg by using a CG value of 27 will be distributed::800 kg to the FW cargo part of the plane and 2.200 kg AFT. If 30 CG is used 900 kg are placed in the FW and 2.100 kg in the AFT part.......  

Regards,

Hanse   

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Privacy Policy & Terms of Use