PSS B772LR - Takeoff Trim

[Guest franksalot]

Is the TO trim set automatically, after completing FMC setup? I've been through all the Manuals but cannot find anything about it. After a couple of 'hair raising' takeoffs (I'm as bald as a Coot :)), I now guess at it.I really enjoy flying this aircraft. KenFYI. The Real World Coot, is similar to a Moorhen, but smaller, with a smooth head :)

[Guest MatthewSchoenberg]

No, in the real world the crew sets the TO trim.Matthew

[FOD 23]

Ken,"I'm as bald as a Coot"In my part of the world nearly, Ken. {And lots of coots and moorhens!}However, the FMC has to leave something for the pilot to do to earn his megabucks. Nowadays not a lot is left but one is;Pre-Take Off ChecksTO trim: Set RegardsJohn R

[Guest franksalot]

Thanks for your reply, Matthew. so I was 'nearly' right when I said i guess the Trim setting? I was/ am concerned because the C of G I get is nearly always I or 2, I would have thought this setting would keep me glued to the runway? So I move the pointer to around 6, that seems to get me off the ground at a comfortable angle. A little 'hit or miss' I would have thought for a Company like Boeing....?Ken

[Guest franksalot]

Hello John, only just read your reply :) difference is, those 'megabuck pilots' get more training than me. Of course, if I hit the ground only my pride is hurt :)Ken

[FOD 23]

Ken,Sorry, perhaps a bit facetious. But when you insert the correct CG into the 777 FMC it calculates a trim setting for your pre-to checks. If you are not getting this from the FMC, please let me know and we can look at your set up.John R

[Guest MatthewSchoenberg]

>Thanks for your reply, Matthew. so I was 'nearly' right>when I said i guess the Trim setting? I was/ am concerned>because the C of G I get is nearly always I or 2, I would have>thought this setting would keep me glued to the runway? So I>move the pointer to around 6, that seems to get me off the>ground at a comfortable angle. A little 'hit or miss' I>would have thought for a Company like Boeing....?>>KenAs John has indicated in his post below the TO trim setting is an exact number in two place decimals and is calculated by the FMC in the final stages of programming. It is more often than not between 4 and 6 and should be set by the trim tabs using the Flight Control screen usually set to the lower EICAS.Matthew

[Guest franksalot]

Hi John and Matthew, I've had a good look at this Trim setup. Everything is as it should be. I use a Saved LoadEdit cfg.so then if I load 42% fuel, I get a Trim of 1.0, is this what you would expect?Am I correct in thinking that this Trim setting is for the aircraft's trim in flight?Ken

[Guest franksalot]

Just a question of Trim really. Any ideas, anyone?Ken

[FOD 23]

Ken,What's your ZFW?John

[Guest franksalot]

Hello John,I have a Flight loaded - ZFW = 169.7 (Kgs)Fuel - 56% I have C of G of 1.0.Looking at the FCTL info the Stab Trim is given as 1.33.Can you tell me, is this for takeoff or inflight Trim.My thoughts re trim are conditioned by nearly 25 years of building and flying Radio Control Aircraft :) Where we 'feed in', via the TX a little 'Up Elevator Trim' before TO. Then re-trim at CRZ altitude!Ken

[FOD 23]

Ken,That's the basics but for real there is a different trim position for every speed/weight etc. We set a specific trim position for TO - which will usually put the aircraft "in trim" at about VR+15 - you then need to re-trim as necessary to reduce the load on the stick throughout the flightThats the simple explanation - you could write a thesis purely on manual longitudinal trimming itself - and then there's the autopilot and fly-by-wire ........But that's another story.If you need more detail, I'll be around tomorrow.RegardsJohn

[Guest franksalot]

Thank you John,you have covered most of what I wanted. My TO's and Landings are improving with every flight; also the start up from C and D are now committed to memory, the Checklists are helpful also.I hope I can leave you in peace for a while now :)Ken