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Strange behave climb

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I try to read in other topic but there are not much people with this problem.I setup my 747F for a short trip I have ZFW 540.7 I charge with 50.8 LBS of fuel setup my fmc with a crz level of 220.When I take off the speed works fine but as soon I engage LNAV VNAV and A/P CMD L the autothrottle have strange behave.The speed goes up and down and the aircraft goes to the limit of stall, but the strange factor is the behave it seams to not follow the speed value neither the autothrottle even if i set the altitude the aircraft goes over the limit.I when is time to descent no way to let the autopilot accept VS or FLCH it dosen't care.I Use normal TO and CLB no reduction and the autopilot can reach 8000 fpm so all the time.I tryed also the pax version but is the same behave If you look to the screenshot you will see the situation.Now i have this phenomena for a quite some time and when I reinstall the software everyting come back as it should but after doing some defragment the problem come back.I don't understand why i have other add-on and this is the only bird who is driving me crazy, and i am sad because I love to fly the cargo.If someone else have pass throw those behave please any suggestion would be helpfull.Thank you.

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Ok maybe those screenshots shows that the THR is working and in any case after push toga and takeoff I diden't disconnect the autothrottle and normally I active the LNAV VNAV and follewed by Autopilot after 400 AGL or more.This act the computer to follow the vertical path as programmed on the FMC and this normally works really well but not in my situation.I menage to fly with the leveld and other add-on, as metion before, after I have reinstall the package it works fine but after defragment the HD and maybe other fatcor of time, it dosen't behave the same.Did you think I am still doing wrong?

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Please sign your name to your posts, it's a PMDG forum rule,I really don't know what's going on. You're in completely different AP and AT modes in each of those three screenshots...

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Yes I have post all the possible situation on use of the A/T so maybe I am right that there is someting wrong it's not the nasa shuttle with particular system .If for example I tell to go to 256 IAS and press spd it dosen't accelerate to the chosen speed it's floating up and down with A/T acceleration.But If reinstall the software it works fine but after defragment my HD this problem come back.If you have some suggestion I wolud be really happy.Thank youSorry for not sign my precedent post.Fabrizio Pascucci

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Fabrizio:It clearly can be seen in your screenshots that, for any reason, your autopilot is not following the flight director bars. (That is what what the autopilot does: he just follows the bars). I don't say it if you are in V/S mode, then, if you demand excessive rate of climb, the autopilot perhaps will not be able to follow and you can stall the bird.Well, I can see (for your menu bar) that you have many aircraft addons installed. Have you loaded more than one of those complex aircraft in the same FS session?.Doing that it normally spoils one of them. And my experience is that the flight director is one of the most probable systems to be spoiled.Yes...there is something strange with your A/P and your flight director.Jose Luis.

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Thank for suggestion Jose>Well, I can see (for your menu bar) that you have many>aircraft addons installed. Have you loaded more than one of>those complex aircraft in the same FS session?.>Not on the same session, I start from the default cessna and then change Aircraft and scenery.>Doing that it normally spoils one of them. And my experience>is that the flight director is one of the most probable>systems to be spoiled.>who knows >Yes...there is something strange with your A/P and your flight>director.That what I am tryng to explain, why this happen and if I have to reinstall should i reinstall all the time the pax and then the cargo, or maybe restart with the 737 and so on.But I can't use the defragment if this cause the spoil of the sistem.My config is a E 6600,Evga 680,Evga 8800 gtx, 2 GB Ram- XPPRO - FS9. I am really sad because I like flyng in vatsim but I can't use the 747.Fabrizio Pascucci

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FabrizioFrom the weights you gave it seems that the trim is set way too high at 6.0 - which will give the very aggressive pitch up.What was the overall route distance, and did the FMC accept the cruise altitude as OK - i.e. no errors?I have had a similar problem, and it turned out to be trim set outside the limits.Hang in there - its worth waiting for.RegardsPeter Lloyd

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Peter you are right, the problem is the trim setting.This time I left 4.0 and the system was working fine, I am doing a lot of short flight so this is was all the time a night mare.But should be the autopilot to change the trim once finish step on climb fase and reduce it.If the FMC tell you to use trim 6.0 why you get those behave?Anywaythank you very much for your help.Fabrizio Pascucci

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Hi Fabrizio,6.0 units is not an abnormal trim setting for takeoff, assuming your CG really is at 21%, and as you say the autopilot will control the trim when engaged.One crucial point: in all the screenshots you still have the gear extended. I'm not surprised the aircraft is not accelerating properly. :) Remember, after rotation, to select gear up when positive vertical speed is observed ("positive rate").PMDG 747 does not have a virtual PNF (Pilot Not Flying) to control flaps and gear, unlike the Level D 767. Is that the cause of your problem?Kevin

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Once engaged, the autopilot takes trim control. It doesn't matter what trim value you had set before for takeoff. So, that should not be the problem in my opinion.Jose Luis.

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Jose LuisI think its a question of time here.The autopilot takes some time to retrim once engaged - if you are already heading towards a stall, there is not too much it can do in time. If the aircraft has just rotated and is heading towards the stars with way too much elevator trim applied - hitting the autopilot is not going to bring salvation. I guess this is why the first priority is to 'fly the plane' before using any labor saving gadgetry.Fabrizio - please could you upload some screenshots of the FMC's VNAV page, PERF page also the Route page to see whats happening with the vertical navigation in this case. Your weights as per your email would never generate 6.0 trim.Good weekend guys!Peter Lloyd

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For your FMC's TO page setup in Pic 2:1) Try FLAPS 20/1000 for LSK 1L . . . but whatever you set here, match your flaps to this setting. (Is that flaps 10 in the FMC, with 15 set that I see?)2) Make sure your pitch trim matches the FMC's trim suggestion on LSK 6R It's gotta be close, or pitch will give you fits (like you're getting).Pic 1:1) The pitch FMA should have transitioned from TOGA to VNAV SPD at acelleration altitude. (You had that set at 1000 feet in Pic 2.) Notice that VNAV SPD is "boxed" in the FMA. That tells me it just transitioned to this mode seconds before this screeny . . . but you are at 4400 feet. That tells me that is was manually engaged (you done it) . . . probably in an attempt to save the TO. Here's the argument: Pitch mode will transition to from TOGA to VNAV SPD at acceleration altitude. From there, only 2 automatic pitch mode transitions are available. Vnav PATH/ALT (at MCP or FMC presets) or FLCH SPD. It will not transition back to VNAV SPD on its own 'till TOD. You re-pressed Vnav in a precarious attitude. The airplane was out of control (climbing hard and slowing down). In CMD/VNAV SPD, the airplane is now trying to save itself. The (new) commander, Captain AFS (Auto Flight System), is just a moment from transitioning to his emergency "FLCH SPD" mode. It's all he's got left. You handed him an airplane that was totally crossed up in pitch and he's trying to save the day. This was a wild ride up to here and it's getting worse. Now, where was that trim set? At this moment, the AFS has the stabilizer trimming nose down like crazy with the elevator also pitching nose down, hard. At this point, a pilot's only real chance would be to just keep his hands in his lap. Let Captain AFS handle this. Try this: Setup for TO. Your pic 2 is fine, just set trim and flaps correctly. Now set the sim for 1/2 speed. Engage the AT. Roll. Rotate at VR. At positive rate and/or 50 feet, engage the AP . . . then put your hands in your lap. Stop pushing buttons! Don't touch nothing except the gear handle and raise flaps on schedule. Just sit there and watch. It'll be fine.Pic 3: (for now) Never climb in VS. It has no speed protection. You'll crash. Climbing in VS been taken out simmers for years. (BTW, you're doin' great. These automated systems take some getting used to!)

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You are right that V/S mode is inapppropriate, but I say again, so is having the L/Gear down during the climb out.The guy signs with a Level-D 767 banner. Clearly he is used to a sim where the F/O takes care of gear and flaps.Kevin

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Thank you so much for all this suggestion, due to my intention on make it, I have create some other screenshot where it shows, what I am talking about.As you can see on the takeoff 03 the speed goes down and if i don't act manually the stall is imminent.But there are days wich works fine and other day, no way that the A/T work correctly.This is the step and also the info of the FP for what I insert in the FMC and MCP.I know the diffrence from the LDS 767 and the PMDG 744F if i have a banner wich i create dosen't mean anyting.I will reread carefully your suggestion and try to understand what I am doing wrong or way this happen, Flight PlanLIRF - LIPE CRZ 220CMPTIBERGITODIXUSIFRZ747400F LoadManager.exe52052 Fuel634976 ZFWPax 2160Cargo 268290FMCGRW 686.3FUEL 51.9ZFW 634.4RSV 16CI 100THRUST LIMITTO CLBTAKEOFF REF10/1000 FTE/O ACCEL 800V1 137VR 151V2 167TRIM 6.0 CG.20%MCPFD on A/T onIAS/MACH 176ALT 22000Thrust to 70% stabilaizeTOGA ButtonFull TrhottleVR RotateAfter V2 Gear UPManual flyng on following the FD400AGL LNAV VNAV AP-L

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FabrizioI just set everything up the same and tried the flight.Worked a treat. Screenshots of the FMC and also of the cockpit on climbout are attached.You didn't have a 100kt tailwind at 500ft agl did you?There has to be something simple happening here. What are your PMDG options set to for overriding the autopilot (AFDS settings I think)?Email me off forum and lets try and work through this from the beginning up.Peter Lloyd

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In pic 4, you didn't let the airplane accelerate to the scheduled "flaps up" retract speed brfore you selected "Flaps Up." Here the deal, I think: Notice the FMC set a clean airspeed of 275 knots. The FMC thinks You are real heavy . . . and you are! Your notes show a GTOW of 957,478 lbs. "747400F LoadManager.exe52052 Fuel634976 ZFWPax 2160Cargo 268290"That's a tad overweight. If you want to try this, that's OK. But there's no telling where the CG is gonna be. If you want to continue these "test flights," try letting the airplane acellerate all the way to the scheduled flap retract speed before you "pull the rug" out from under poor ol' Captain AFS. Even overweight, it appears you were OK just prior to this flap retract event. The deceleration that is occurring here means the nose was lower just a second ago. Something happened to rock the nose up. Look at the FD bar. This means the Autopilot has the stab trimmin' nose down and the elevator pushing hard to get the nose down ImmdeIaTEly. Something upset the airplane, just moments before. It might have been that early flap retraction. Try it again and retract the flaps right on schedule . . . not early . . . then try it at 1 million lbs! You're our new test pilot. How heavy can you go???Pics 1 through 3 look OK . . . except, make sure the To page flap selection (LSK 1L) and the actual flap setting match before TO.

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Just a quick comment... and not totally relevant to your problem.. but why don't you have LNAV and VNAV armed before the take off roll?CheersCraig

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>The FMC thinks You are real heavy . . . and you>are! Your notes show a GTOW of 957,478 lbs. >>>"747400F LoadManager.exe>52052 Fuel>634976 ZFW>Pax 2160>Cargo 268290">I think you may be confusing ZFW with OEW :)GW = ZFW + Fuel = 687,028Kevin

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