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maximus92

Trim for Takeoff

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Over the past couple of years, since joining Lufthansa VA, I have slowly added more and more realism to my flights. Gone are the days when back in FS98 I would take off in my Cessna, fly around aimlessly, and then try to land in the Vatican :( . I've taken the hobby a little more seriously, realizing that the fun has always been to learn how to actually fly the heavies. One thing that eludes me is the term "set the trim for takeoff." I know what trim is, but how do I know it's properly set for take off? I've noticed a green area on the trim wheel gauge, am I to set it somewhere in there? What other factors determine how much trim I need for take off? I imagine winds, and weight add into it. One thing I have noticed is that when I press the TO/GA button on takeoffs, some planes, when they reach a certain speed, will take off and maintain a consistant climb, until I engage the AP and such. While other times I manually have to pull the yoke back to attempt to take off (sometimes the plane just floats along the runway with the nose up.) Does this have anything to do with the lack of trim I'm setting?

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In theory, the information should be handed to you as the Captain. If you have any of the FS2Crew add-ons, you'll notice many of them have a stage where you 'sign' a sheet during the pre-flight. Although in the case of FS2Crew, it is often just a static page which you see, in reality this would be a form (or series of forms) which have information relating to how much fuel they have put on board and the weight and distribution of the cargo and where the centre of gravity is on the aircraft based on all that information. This is called the 'Load and Trim Sheet' although is sometimes referred to by other more colloquial names, such as 'zig zag' because of the graph which appears on the sheet, which draws a zig-zagged line through various points and checkboxes on the columns to indicate things such as flap settings and trim etc.This information is something which the loadmasters, ramp agents, or airline cargo people calculate when loading the aircraft with freight and such; it's one of the reasons why you have to check your baggage in a long time before you board a flight and why you see it being weighed. Bags and freight are usually put into a ULD (Unit Load device) which are the standard airliner freight containers you often see being carted across the airport apron on baggage trucks, or going up conveyer load ramps into aircraft's holds. The weight for passengers and the effect they have on the Centre of Gravity are based on standard figures - typically 70 kg for adults and 30 kg for children.More sophisticated calculation systems for setting up the trim on an aircraft download all the load information to a laptop which the pilots have, which can then be plugged into the aircraft and dump the data directly into the FMC. Airlines with this kind of set up mean that the crew can do much of the flight planning in a crew room with a nice cup of tea or coffee before they actually board their aircraft. so if you indulge in that sort of planning in FS, have a drink to add to the authenticity.Once you have that information (by whatever means), you can enter the Centre of Gravity information (often expressed as a percentage of how far it is from its normal position when the aircraft is at its dry operating mass) into the FMC, which, depending on the aircraft systems, will either automatically adjust the trim for you, or give you a figure to set manually via the cockpit trim controls.As far as FS is concerned, you'll find most sophisticated add-on airliners have a 'load configuration utility' of some sort (usually accessible from the PC's program menu). So you could observe how the CoG is affected based on your virtual load and work it out from there, although without knowing the specific aircraft, or having a proper load sheet for the aircraft, it might involve a bit of trial and error. With less sophisticated FS ailiners you could just use the FS fuel and load options. You could try Googling 'load and trim sheet' and you might find some real load sheets online, but I don't know for sure, also you might try the real aircraft's manual (you can often google and find a pdf of these). I have one for a 737 if that helps you (PM me if you want a copy)You might find this accident report interesting, scroll all the way down and you will see a load sheet at the bottom of the report:http://www.bfu-web.de/nn_53140/EN/Publicat...rtmund_B737.pdfHope that helps a bit. Al

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Honestly it depends. Normally this is found through POHs though, generally, the dispatchers figure all that out and put it on dispatch releases. You don't get those in FS unless you're with a VA such as MidCon who actually prepares dispatch releases for you. I do know that the Wilco/feelThere 737PIC shows the trim setting for take-off on the TAKEOFF page in the FMC, so you may find it there in some other add-ons.

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Trim is generally set appropriately according with other parameters, such as the take off data you have ( Consisting of alot of things such as flap settings, OAT etc ). , but also calculated to maintain an appropiate speed upon climb out ( Which you probably knew yourself but was just to say again ).Generally you can judge just about what trim setting to have, referenced to take off speed and weight upon the climb out, as you don't wanna set trim which will when pulling back on the yoke the nose goes sky high while your still on the ground ;).I know for the 747-400 i fly, ( On IVAO as UAE19 if you were curious ) doing the take off performance data helps alot, even if you don't entirely understand all of it.Speaking of Take off data performance, try it out :D. While it may seem difficult to get into it brings out the realism quite alot while making it easier for your own knowledge of what you could expect.Procedure makes it all easier ;)Regards,

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short answer...put some positive trim in...see how it handles

Over the past couple of years, since joining Lufthansa VA, I have slowly added more and more realism to my flights. Gone are the days when back in FS98 I would take off in my Cessna, fly around aimlessly, and then try to land in the Vatican :( . I've taken the hobby a little more seriously, realizing that the fun has always been to learn how to actually fly the heavies. One thing that eludes me is the term "set the trim for takeoff." I know what trim is, but how do I know it's properly set for take off? I've noticed a green area on the trim wheel gauge, am I to set it somewhere in there? What other factors determine how much trim I need for take off? I imagine winds, and weight add into it. One thing I have noticed is that when I press the TO/GA button on takeoffs, some planes, when they reach a certain speed, will take off and maintain a consistant climb, until I engage the AP and such. While other times I manually have to pull the yoke back to attempt to take off (sometimes the plane just floats along the runway with the nose up.) Does this have anything to do with the lack of trim I'm setting?

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Someone say it. Takeoff trim depends directly on aircraft center of gravity (CoG) and takeoff weight (TOW). Most of your single and multi light aircraft (maybe all) trim to the neutral position. But in heavier aircraft, trim is *very* important at takeoff. Only more realistic addons simulate the exactly correct trim settings at takeoff, but for your utterly unrealistic aircraft (default, Posky, etc.) VTX is correct. A little nose up trim is a good start. Speaking of trim, read my signature. That's another trim issue I stress to newer guys at the flight school (works the same in flight simulator).

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Absolutely. Being a glider pilot, I regard the trim control as the throttle.Al

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Absolutely. Being a glider pilot, I regard the trim control as the throttle.
You might..........................but if it comes to any formation type flight (at least with an engine) , then it's throttle for airspeed; and elevator control as secondary when required. You'll never want to be thinking throttle for altitude in this case!This is why I love the throttle for altitude and elevator for airspeed argument......................as I always side on the throttle for airspeed side. In fact, I think it's even on the side of error to even teach it as one way. Of course, a student pilot does need to know that it's power for altitude when on the backside of the power curve for landing approaches. I'll just assume that's why it's taught. I think it's better to just say that required actions are a combination of both rules...............most of the time. My favorite cartoon in regards to this, is a student pilot nervously flapping the elevator in order to get the plane rolling down the runway. Remember, he was taught elevator for airspeed! :( L.Adamson

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When I say I use the trim as a throttle, unlike in a powered aircraft, that generally is for airspeed in a glider. I leave the altitude up to the thermals!With regard to formation flying, since you are often aerotowed up to 2,000 feet or more, you have to be pretty good at formation flight when you fly gliders, so it also comes into play there. One of the first exercises glider pilots do when learning aerotowing is to 'box the tow', where you move out to one side, drop below the slipstream of the towplane, come back to the middle, come up to the slipstream to feel it on the canopy and learn its position, then come back up the other side. You have to be very careful not to upset the towplane when so far out to the side. Good airspeed control is vital to avoid snapping the towrope if it slackens for a second or two.It's also not at all unusual to be in very close proximity to other gliders when you find a good thermal. I've been thermalling in a glider when the sky was reminiscent of a WW1 dogfight there were that many aircraft turning about all over the place. You hand is never far away from the canopy jettison handles in those circumstances!Al

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You might..........................but if it comes to any formation type flight (at least with an engine) , then it's throttle for airspeed; and elevator control as secondary when required. You'll never want to be thinking throttle for altitude in this case!This is why I love the throttle for altitude and elevator for airspeed argument......................as I always side on the throttle for airspeed side. In fact, I think it's even on the side of error to even teach it as one way. Of course, a student pilot does need to know that it's power for altitude when on the backside of the power curve for landing approaches. I'll just assume that's why it's taught. I think it's better to just say that required actions are a combination of both rules...............most of the time. My favorite cartoon in regards to this, is a student pilot nervously flapping the elevator in order to get the plane rolling down the runway. Remember, he was taught elevator for airspeed! :( L.Adamson
If an aircraft is trimmed for steady level flight and the throttle is opened the aircraft will begin to climb. Allowing the transients to subside, the aircraft will settle doen in a steady climb at just about the original airspeed. To increase speed in steady level flight it's necessary to open the throttle and trim the aircraft nose-down.I suggest that it's fairer to say that throttle adjusts rate of climb and trim adjusts speed. I was certainly taught on approach to trim for speed and adjust my touchdown point by changing the throttle. This is what the underlying physics suggest. All else being equal, additional power is needed to make the aircraft clmb at the same steady speed.

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If an aircraft is trimmed for steady level flight and the throttle is opened the aircraft will begin to climb. Allowing the transients to subside, the aircraft will settle doen in a steady climb at just about the original airspeed. To increase speed in steady level flight it's necessary to open the throttle and trim the aircraft nose-down.I suggest that it's fairer to say that throttle adjusts rate of climb and trim adjusts speed. I was certainly taught on approach to trim for speed and adjust my touchdown point by changing the throttle. This is what the underlying physics suggest. All else being equal, additional power is needed to make the aircraft clmb at the same steady speed.
Physics has still never figured out exactly "what causes lift". So let's get past the physics issue as an explanation. So..................say we're headed down the runway thanks to "throttle". At 60 kias or so, we want to rotate and climb. What do we tell the student? Use throttle to climb, or get with the program and pull back on the stick (elevator). And what about decending to make a high speed pass down the runway? Do we use elevator as the primary control process, or descend & climb with throttle? It's now elevator and primary and throttle as secondary. Getting back to what you were taught on landing is correct. But once again we're on the back side of the power curve as I originally noted.Do you realize that this same subject erupted into hundreds of responses a few years back? Nothing was settled then, and probably never will be! L.Adamson

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Physics has still never figured out exactly "what causes lift". So let's get past the physics issue as an explanation. So..................say we're headed down the runway thanks to "throttle". At 60 kias or so, we want to rotate and climb. What do we tell the student? Use throttle to climb, or get with the program and pull back on the stick (elevator). And what about decending to make a high speed pass down the runway? Do we use elevator as the primary control process, or descend & climb with throttle? It's now elevator and primary and throttle as secondary. Getting back to what you were taught on landing is correct. But once again we're on the back side of the power curve as I originally noted.Do you realize that this same subject erupted into hundreds of responses a few years back? Nothing was settled then, and probably never will be! L.Adamson
If not physics what does "figure out" what causes lift?I was careful to refer to steady flight - your examples relate to non-steady flight. If an aircraft is longititudinally trimmed and in steady flight stick force is zero. Taking off and making high speed passes where the stick force is not zero is not steady flight.What I was taught for landing applies regardless of what side of the drag curve the aircraft is. If the aircraft is trimmed at a steady speed in a descent then the touch down point can be adjusted by the throttle while mainaining the same speed. The reason is basic physics. An aircraft in that condition has a rate of descent and is loosing energy - the drag is greater than the thrust to compensate for the component of the aircraft weight. If the aircraft is undershooting then opening the throttle and increasing power will add energy to the aircraft. This will reduce the rate of descent so that the the touch down point will move further down the runway.Enegy management is a key aspect of handling heavy and/or fast aircraft."Inability to assess or manage the aircraft energy level during the approach often is cited as a causal factor in unstabilized approaches "http://www.airbus.com/store/mm_repository/...-APPR-SEQ03.pdf.

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Physics has still never figured out exactly "what causes lift". So let's get past the physics issue as an explanation. So..................say we're headed down the runway thanks to "throttle". At 60 kias or so, we want to rotate and climb. What do we tell the student? Use throttle to climb, or get with the program and pull back on the stick (elevator). And what about decending to make a high speed pass down the runway? Do we use elevator as the primary control process, or descend & climb with throttle? It's now elevator and primary and throttle as secondary. Getting back to what you were taught on landing is correct. But once again we're on the back side of the power curve as I originally noted.Do you realize that this same subject erupted into hundreds of responses a few years back? Nothing was settled then, and probably never will be! L.Adamson
Now, if from straight and level flight, I pull the plane into a vertical climb, how come my airspeed starts dropping even when I apply full power. I mean, I pushed the power all the way forward, I should be going really fast, shouldn't I?The only reason this same subject erupted into hundreds of responses a few years back is because you and P.Sidoli are just insanely stubborn about how "right" you think you are.

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Now, if from straight and level flight, I pull the plane into a vertical climb, how come my airspeed starts dropping even when I apply full power. I mean, I pushed the power all the way forward, I should be going really fast, shouldn't I?The only reason this same subject erupted into hundreds of responses a few years back is because you and P.Sidoli are just insanely stubborn about how "right" you think you are.
All you're proving is that there is NO exact rule that applies to everything. Let's again use the straight and level flight....................but in tight formation. What control, as a wing man, are you going to use to keep exact pace (airspeed wise) with the lead? It sure as ****, better be the throttle! In fact, throttle is so important, that any type locking veneer is against formation flight policies.P.S. ------ how do you pull that plane into a vertical climb? Just jam the throttle full forward? If you've already got the "speed", then convert it to altitude with the "elevator". It's all realitive isn't it? To just use "pitch for speed and throttle for altitude" as the ultimate answer is just stupid! Always has been, and always will be!L.Adamson

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If not physics what does "figure out" what causes lift?
Do you think that "lift" has been scientifically explained, and is fact?Or, does it go into the "where does space end", file...L.Adamson

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