Hi guys and happy new year to everyone ! Is there a way to know exactly how much trim is needed for tkof/ldg in regards to the airplane load (%)/weight ?
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I use 15% trim for everything regardless of weight etc.
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I generally use 5-10% for takeoff and for landing the amount varies depending on weight
This has a lot of them:
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Hi, and happy new year.
I don’t normally adjust trim for takeoff as I’ve found my device pitch rotation range is almost always sufficient to comfortably deal with any dynamic change in the zero-pitch input position.
That is, I effectively trim by sensing device pitch range alone for the current flight state.
The zero pitch input position that trim adjusts would presumably change if center of gravity changes due to differences in weight.
But testing with MTOW vs lower weights for a few cases didn’t seem to make much difference.
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I generally use 30% trim on most aircraft for take offs and landings if I don’t have any information about it.
If you are flying the new B737-8 MAX on the YouTube tutorial Tyler (or whoever does the voice over on the videos) said that to divide what load percentage you have by 3 to get your takeoff trim.
Is that work for every aircraft ?
This is tested on the new MAX which has updated and realistic physics because it’s the newest in the simulator. I’m not sure about the others because some are outdated so therefore have outdated and unrealistic physics.
So, you’re saying there is a nose heavy bias to the loading model?
If the load increase is balanced so the center of gravity doesn’t change much, it should have little effect on needed trim.
I you look at the numbers in the linked guide and various people’s personal preferences, you’ll see quite a range.
The golden rule for trim is: use what you have tested for yourself to give you a comfortable control result.
Trim is an irl effect to balance changing forces about a pivot point, like for placing people on a seesaw so that it doesn’t tend to rotate to a position away from where you want it (go out of balance).
As long as it’s comfortable for you to rotate and hold to your pitch goal, your trim use is good.
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I’m clueless about trim, never used it (apart from 30% landing on a330)
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At the end of the day, trim depends on several factors like weight, speed, winds, and more. I don’t usually follow a one-size-fits-all approach. Instead, I base my trim adjustments on what eliminates the magenta or green line on the trim bar. This method gives me better control over the aircraft, especially during landing, ensuring the nose doesn’t drop or rise unexpectedly when disengaging the autopilot.
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Important point:
As for:
To be honest, I can’t see how wind would have any effect except maybe when wind is changing causing some transient IAS related effects (maybe something I don’t understand?).
But weight and speed affect how much angle of attack for a given amount of lift which (even when the added weight doesn’t change center of gravity), will affect how the forces are distributed “along the seesaw from the pivot point.” So affects trim position.
Weight distribution of course affects trim as well.
But differences in trim for heavier loads at takeoff (assuming balanced load) are likely to be moderated by takeoff speeds adjusted higher and/or increased flap settings (though the caveat is different flap settings likely change the center of lift, which would have some effect on trim).
From my experience, the slower my aircraft is, the more trim I need to eliminate the magenta line. Wind also plays a big role in ground speed—the stronger the headwind, the slower your ground speed, and vice versa. I’m not an expert by any means, but this is what I’ve observed in the app.
Yeah, that’s like irl: you’ve got to make up for the changing balance in force between the wing and the horizontal stabilizer as airspeed changes.
True, but the trim would be affected by the airspeed rather than the ground speed because the changing trim forces are related to the aerodynamic forces, which the aircraft experiences due to IAS (so you might be flying in Hurricane winds, but for IAS the same, your trim would be the same).
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I feel like I don’t need to trim when taking off, because of the device calibration. But I set it at 5-10% depending on my weight.
When landing, I trim until there’s no green line/dot on the trim slider. That will prevent the sudden sink/drop or sudden nose up after turning off AP (even when calibrated).
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I have made trim tables for the aircrafts I used to fly (test flights based trim values against weight and IAS @ different altitudes). For TO, I use what the good trim value would be at V2 +10. It works well.
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I just got my information from the B737-8 MAX tutorial. I also mentioned that this method only works for the MAX.
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Understood. It’s possible they built in some weight distribution drift tendency (away from the center of lift) as the load increases. Of course you have, pax, fuel and cargo to deal with. It’s possible the center of mass location of the average such load tends to change with the amount of load (the specifics of the particular situation are beyond my knowledge).
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I saw something like this in a YouTube tutorial on flying the 737-8 MAX. It showed that you can calculate the trim by dividing the airplane’s load percentage by three. Since then, I’ve been doing this before taxiing for takeoff and before landing
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Ah, thanks, I’ll test this method next flight