the blip trim is annoying

[Tabs 2,790]

I had the chance to fly a level D full flight 777 sim again a few weekends ago and I paid very close attention to the trimming feel and stuff. I do think we have it as close as we can get within the FSX environment. We'll never be able to fully replicate the real experience until something comes out that can do physical control force/loading the way the real yoke does. It *is* extremely intuitive in the real airplane, you just trim until the force is gone and you can hold the yoke position with your fingertips. We can't replicate this with flimsy joysticks and yokes, so there's a lot more physical deflection required (which is the loading simulation we mention in the manual) than there is in real life. It's always the same amount of yoke movement in the real thing to command a given pitch maneuver regardless of how out of trim you are. What changes is how difficult it is to push or pull the yoke that distance. There's just no way to replicate this in FSX without some kind of hyper-realistic force feedback controller that we could send a force curve to constantly.

 

Also - someone up above mentioned the plane slowly deviating from level with hands off when in trim. The real thing does this - I noticed it a bunch flying the sim. The system isn't an autopilot, you can't just take your hands off it and expect it not to drift at all. Think of it as being similar to driving a car on a long straight freeway - the steering generally holds but you often need to make small little corrections with your fingertips on the wheel. It's the same deal with an airplane. If you want it to perfectly hold things, turn on the AP.

The blip trim works as best I could tell exactly as we have it programmed. I specifically tried the opposite direction scenarios and stuff and it sends it to the current airspeed regardless of which direction you trim in as long as you're within 5 knots of the trim reference speed. Again with this I think people are reacting to the fact that they can actually see the ref speed changing in FSX whereas in the real aircraft you can't. If you're out of trim and you blip trim to current airspeed - you *should* see a pitch reaction to that, that's normal. Keep your airspeed constant after doing it and you shouldn't see any more aside from the minor drift stuff I mentioned above.

I follow the blue FBW speed bug quite much because it is very useful as an orientation, nevertheless its use is "unrealistic" as it is not displayed in the RW T7. I ask myself why it is actually not depicted on the RW speed tape. Could be helpful for manual flight in general or even more during abnormal flight conditions.

BTW: I like the T7's stabilizer auto trim restriction to flap and gear configuration changes quite much. IMO it is superior to the Airbus philosophy in terms of man-machine-interface.

 

You don't need it in the real airplane because you have the immediate tactile feedback from the yoke force/pressure - the airplane physically tells you when it's out of trim through this. You trim until the pressure is gone, that's it.

[cmbaviator 5]

I had the chance to fly a level D full flight 777 sim again a few weekends ago and I paid very close attention to the trimming feel and stuff. I do think we have it as close as we can get within the FSX environment. We'll never be able to fully replicate the real experience until something comes out that can do physical control force/loading the way the real yoke does. It *is* extremely intuitive in the real airplane, you just trim until the force is gone and you can hold the yoke position with your fingertips. We can't replicate this with flimsy joysticks and yokes, so there's a lot more physical deflection required (which is the loading simulation we mention in the manual) than there is in real life. It's always the same amount of yoke movement in the real thing to command a given pitch maneuver regardless of how out of trim you are. What changes is how difficult it is to push or pull the yoke that distance. There's just no way to replicate this in FSX without some kind of hyper-realistic force feedback controller that we could send a force curve to constantly.

 

Also - someone up above mentioned the plane slowly deviating from level with hands off when in trim. The real thing does this - I noticed it a bunch flying the sim. The system isn't an autopilot, you can't just take your hands off it and expect it not to drift at all. Think of it as being similar to driving a car on a long straight freeway - the steering generally holds but you often need to make small little corrections with your fingertips on the wheel. It's the same deal with an airplane. If you want it to perfectly hold things, turn on the AP.

 

The blip trim works as best I could tell exactly as we have it programmed. I specifically tried the opposite direction scenarios and stuff and it sends it to the current airspeed regardless of which direction you trim in as long as you're within 5 knots of the trim reference speed. Again with this I think people are reacting to the fact that they can actually see the ref speed changing in FSX whereas in the real aircraft you can't. If you're out of trim and you blip trim to current airspeed - you *should* see a pitch reaction to that, that's normal. Keep your airspeed constant after doing it and you shouldn't see any more aside from the minor drift stuff I mentioned above.

 

You don't need it in the real airplane because you have the immediate tactile feedback from the yoke force/pressure - the airplane physically tells you when it's out of trim through this. You trim until the pressure is gone, that's it.

 

 

Ok thanks.

 

Please tell me if you agree with this as you've been on a LEVEL D T777 Sim :  

 

http://forum.avsim.net/topic/450359-t7-pitching-to-rapidly-after-changing-the-trim-reference-speed/

[vr-pilot 11]

 

 

You trim until the pressure is gone, that's it.

That is basic as in a B737 or C172 actually. I like this very much as it gives the pilots the "FBW real feel" in contrast to the insensitive Airbus stick inputs ("flying carpet philosophy" as I would call it; "stable platform", that's what they call it).

 

 

 

It's always the same amount of yoke movement in the real thing to command a given pitch maneuver regardless of how out of trim you are. What changes is how difficult it is to push or pull the yoke that distance.

So the yoke column deflection is "proportional" to the RELATIVE pitch command (DEG) and just the amount of trim deviation is calculated back to the "force feed back" of the column?

I wouldn't like this system too much if the column force is based on a "trim reference speed vs. IAS" evaluation ("pure ADIRS-model").

I would favour a system that calculates the force feed back on the columns based on the actual "elevator vs. stabilizer position" ("aerodynamic model"). That could represent the actual forces on the elevator surface at a given airspeed (again more B737 or C172 style).

Do you know which evaluation ("pure ADIRS-model" or "aerodynamic model") Boeing takes into consideration? Perhaps a combination of both?

[pete_auau 1,171]

Please tell me if you agree with this as you've been on a LEVEL D T777 Sim :

Its been answered by Rob already and has explained it

[BeechPapa 32]

Also - someone up above mentioned the plane slowly deviating from level with hands off when in trim. The real thing does this - I noticed it a bunch flying the sim. The system isn't an autopilot, you can't just take your hands off it and expect it not to drift at all. Think of it as being similar to driving a car on a long straight freeway - the steering generally holds but you often need to make small little corrections with your fingertips on the wheel. It's the same deal with an airplane. If you want it to perfectly hold things, turn on the AP.

 

I read or watched something on the 777 that stated Boeing left natural oscillations and dynamic modes intact even though they could have easily neutralized them via fly by wire. They explained that the oscillations give pilots feedback which they are used to getting on normal planes whose oscillations are not artificially suppressed. Natural aerodynamic forces or imbalances acting on the 777 are not hidden from the pilot, and he is a necessary part of the feedback/response loop when flying. It seems redundant, but with the technology the way it is, it's an active choice to leave "error" or "imbalance" in the equation - and a very clever one, I think. As far as I know the original implementation of FBW on Boeing fighter jets aimed to completely remove oscillations from straight and level flight, so the airliner implementation is divergent, and for very interesting reasons.