C*U

[fstulm 4]

Hello all,

 

I have seen a lot of information regarding the service pack updates and the massive changes that the 300 and SP1d bring in terms of flight controls model and autopilot logic.

 

Q1: How come that such a radical difference had to be implemented after the initial design?

• Was it due to latter discoveries about the real design/behavior of the aircraft?
• Was it to make it more user friendly?
• Was it to make it more realistic?
• Was it to reduce complexity as compared to the real airplane and therefor easier to run on a limited environment (FSX) and hardware resourced at a minimal cost to realism?

I am assuming that given your (PMDG) expertise you know from the start what it is that you want implemented and then just corrections follow as it is a massively complex undertaking.

 

Q2: As they stand now, with all latest patches on 200 and 300, are there differences in the FBW and AP implementations of the two models?

• What are these differences and why? I know the two airplanes have a real massive difference in terms of size and performance but the FBW and AP basic logic should still be the same is it not?
• Which of the two stands closer to the real thing?

My main interest is in how close to the real C*U behavior are these birds when hand flying them. I know that this is a very hard intellectual property of Boeing and this is what really makes this awesome aircraft what it is; as such, aside from a few publications that I read on the subject, it is after all a real industrial secret and real equations are not given away.

 

I apologize in advance if this topic has been addressed before and there are other threads close to this topic.

 

Sincerely,

Ionut (John) G. Micu

[Lashrathius 49]

Q1: How come that such a radical difference had to be implemented after the initial design?

• Was it due to latter discoveries about the real design/behavior of the aircraft?
• Was it to make it more user friendly?
• Was it to make it more realistic?
• Was it to reduce complexity as compared to the real airplane and therefor easier to run on a limited environment (FSX) and hardware resourced at a minimal cost to realism?

I am assuming that given your (PMDG) expertise you know from the start what it is that you want implemented and then just corrections follow as it is a massively complex undertaking.

 

I remember reading somewhere in the manual that inaccurate information of the FBW was given to PMDG by a trusted source when they implemented and released the RTM version.

[downscc 1,327]

As far as Boeing intellectual property goes, PMDG has a commercial relationship with Boeing and access to engineering. As far as simulation fidelity I don't think you'll find any better any products in this price bracket for the simulation platforms they target.  Each current product has a technical advisory team to assist in the development that only includes type rated pilots for that product.

[Mike777 163]

Hi, Ionut,

 

The original 777 RTM was actually a bit easier to fly than the current version, because autotrim was active when it wasn't

supposed to be.

 

I remember the same explanation as Henry in Post #2; not sure if it is in the manual or somewhere in the PMDG forums.

 

Mike

[fstulm 4]

Thank you for your responses, it does fly very smooth and it if for sure second to none! I can't wait to build my dedicated controls for it ...

 

Ionut (John) G. Micu

[kevinh 409]

C*U is not Boeing proprietary as far as I know. Even if it is, the way it works is public knowledge. The current FBW model replicates C*U fairly well (unlike the original release which was in effect C*) but is not perfect. From what I can see as an outsider (so I could be wrong), the effects of C*U control have been simulated, but not by using C*U control techniques. Maybe that wasn't possible in FSX, though it is fairly straightforward mathematically.