FMC seems always to show a Trim of 4.8?

[ixam500]

Hey guys, 

I just noticed that the FMC always seems to show a trim value of 4.8, no matter what the IXEG "loading" interface says.

Is it supposed to be like that or just not an implemented feature?

Thank you very much for this great aircraft btw, it really rocks! 

[HerrSchwarz]

5 hours ago, ixam500 said:

Hey guys, 

I just noticed that the FMC always seems to show a trim value of 4.8, no matter what the IXEG "loading" interface says.

Is it supposed to be like that or just not an implemented feature?

Thank you very much for this great aircraft btw, it really rocks! 

Has been repoted a couple of times allready.

[cmbaviator]

7 hours ago, ixam500 said:

Hey guys, 

I just noticed that the FMC always seems to show a trim value of 4.8, no matter what the IXEG "loading" interface says.

Is it supposed to be like that or just not an implemented feature?

Thank you very much for this great aircraft btw, it really rocks! 

 

yeah it has been already been reported, I think i was the first one to do so xP

the CG value has to be entered in the FMC but you can't currently as it is always stuck to 10.1% => 4.8°. just apply trim to meet the trim value in the ground service menu

[Litjan]

correct, will be fixed...eventually ;-)

For now just do like cmbaviator said!

Thanks, Jan

 

[ixam500]

1 hour ago, Litjan said:

correct, will be fixed...eventually ;-)

For now just do like cmbaviator said!

Thanks, Jan

 

Perfect, thanks

@Litjan Heute zuhause geblieben (wg Streik)? 

[Tom Stian]

5 hours ago, cmbaviator said:

just apply trim to meet the trim value in the ground service menu

good information , thank you 

[HerrSchwarz]

So since we´re allready talking about the TRIM. Can someone pls clearify what the optimum CG is ? How do i know if i have lets say a GW of 50 tons what the perfect CG would be? normally the fmc calcuates it for me but this does not work yet, right? So how do i set the CG perfectly now? I hope im not getting something twisted here and blame myself.

Edited April 27, 2016 by HerrSchwarz

[cmbaviator]

So since we´re allready talking about the TRIM. Can someone pls clearify what the optimum trim is ? How do i know if i have lets say a GW of 50 tons what the perfect trim would be? normally the fmc calcuates it for me but this does not work yet, right? So how do i trim perfectly now? I hope im not getting something twisted here and blame myself. [emoji6]

Lol, read above, in the ground service pop up,

Also trim value is based on Cg and not weight

[HerrSchwarz]

45 minutes ago, cmbaviator said:

 

 

Lol, read above, in the ground service pop up,

 

Also trim value is based on Cg and not weight

Thats what i mean. The CG not the trim sry. How do i know the right CG ? Edited the Orginal Post.

Edited April 27, 2016 by HerrSchwarz

[cmbaviator]

Thats what i mean. The CG not the trim sry. How do i know the right CG ? Edited the Orginal Post. [emoji6]

The right CG is the one given in the ground service pop up menu

[daemotron]

The CG is not given in the ground service pop up menu, but has to be set (default is 20% MAC). I think HerrSchwarz's question is more pointing at "what CG would be realsitic for a GW of X tons". To illustrate that, I have emptied the aircraft of all payload and fuel to demonstrate that the CG still points at 20% (unless you change it - cf attached screenshots).

If  I remember correctly, this was already discussed during development phase - there's a thread about load mgmt somewhere, concluding that IXEG will not take care of the load management, since this is normally not the pilot's job. Remains the (very valid) question what is a good value to set...

The CG is not directly depending on the GW. When the aircraft is empty (no fuel, no PAX, no cargo) it does have a distinct EW and CG (which is individual per aircraft, not by type, so usually you get this information alongside with the aircraft from the manufacturer). Adding fuel normally changes this in a characteristic way (since fuel is normally always distributed the same way when fuelling - wing tanks first and balanced, then center tank). So fuelling to an amount of x kgs should always result in the same CG (as long as there's no other payload). As soon as you change the ZFW (i. e. add PAX or cargo), the story starts becoming interesting: normally the CG impact is calculated based on seat row population and assignment of cargo to the FWD and AFT cargo compartments.

Since you don't have most of this information (neither the neutral CG, nor the fuelling impact nor the redistribution of PAX and cargo), you cannot calculate the correct CG (even if you have a load mgmt software for a 733 at hand), you can only set the CG to something convenient. Something resulting in a TO trim of between 2 and 5 (i. e. valid TO trim range) is technically ok - just keep in mind that the CG is travelling forwards during flight (fuel is being stored behind the CG), so if you already take off with a very low CG (e. g. 4%) you will have a very "heavy nose" on flare...

The proposed standard value (20%) is well chosen by IXEG - althoug you will rarely have such a nicely balanced aircraft, this hits quite the middle of the allowed TO trim range.

 

 

Edited April 9 by daemotron

[HerrSchwarz]

WOW! 

Thank you very, very much for taking the time for such an detailed Answer, sir. Thats what i like about our community. :-)
That clearifys a lot for me. Thanks again. I just wish i could vote this post more then ones.

 

 

Edited April 27, 2016 by HerrSchwarz

[cmbaviator]

I don't understand???, you can manually move the CG of the aircraft, you just have to apply the trim indicated in the ground service popupand not the value indicated by the FMC always stuck to 4.8

CMB

Sent from Tapatalk