Hey guys,
I just started the SIA 22 flight route (WSSS-KEWR) going over the Pacific in a Boeing 787-10. I have been having issues with fuel efficiency. I am 2 hours into flight, and my remaining fuel can bring me there with a minute to spare. I am expecting a nice tail wind in a few hours, and I am waiting to shave off some of my load so I can make a few step climbs. In the mean time I was wondering about the trim setting; what should I set my trim to for best fuel efficiency?
Adjust the trim until the pink bar goes away.
Also, thereâs no such thing as a 787-1000. Only the 787-10, -9, and -8
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The 787 regardless of weight tends to sit around the 50% trim mark. Its not uncommon to be in flight for 2 hrs and appear to be short on fuel by 3 hours. As you burn off fuel, which is weight, less power is needed to keep the aircraft aloft and moving at the speed that you need it to be at. Less power equals a lesser/lower fuel burn. By the time you arrive at KEWR youâll end up having about 10% fuel if you took off with 95%. I did the flight over this past weekend and it was a success.
May the tailwinds forever be in your favor.
Flight time at M.86 was 17hrs 25 mins.
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Holy moly 50% trim? Didnât know you were supposed to use that much while cruising. I guess I learned something new!
I donât use that much trim for the 78XâŚ
TBH, I only use 30% trim because I think the aircraft doesnât need to pitch too highâŚand it seems fine.
Itâs only an opinion
Just look at it this way. Those who donât use trim will be the ones who run out of fuel first. đ
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Itâs only based on my gut and other experiencesâŚđŹ
Trim doesnât do anything while the AP is holding altitude. Iâm assuming you guys arenât hand flying for 17+ hours but it sounds like youâre seeing effects from trim. This shouldnât be possible, can either of you explain this?
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While somewhat true, it actually does have a huge impact. And noticeable in overnight or long haul flights. Its noticeable in the fuel burn. What its doing is relieving the back pressure needed to hold the aircraft in level flight. By reducing this back pressure, youâre reducing drag which means your aircraft is more slippery in the air. Which in the end results in less power needed to get the aircraft moving at a constant rate
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I actually never knew that. Thatâs super cool. Iâll make sure to trim my aircraft in flight. Now we just need a âwhat is your favorite trim setting for aircraftâ topic. đ Iâm just kidding, youâve seen way to many of those. Poor Deer Crusher
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This wasnât the 787-10, but the 747-200. I was doing a 15 hour overnight flight in the 742, and it looked like I didnât have enough fuel, even though I packed it full as that was what simBrief said to do. I didnât know what trim was (this was a flight in my first two months of IF), so I left it alone. I crashed and got 6 vios. I was upset, but wasnât on the IFC and didnât know what the IFC was so I just waited a week to get back on TS1 (I was grad 2 then). Now (like right as Iâm sending this message), I am trying an overnighter from KDTW to RKSI on a Northwest 747-200 and I have adjusted the trim to 66% which is the usual trim in a 747 of all variants, and so far my fuel is looking great!
It actually doesnât, I highly encourage everyone to try it out for themselves. Once the aircraft re-stabilizes it will have the exact same fuel burn as before. Iâve tested this pretty thoroughly since I exclusively do ULH flights.
For example, the current flight Iâm doing had 15:40 minutes of fuel remaining at 0% trim. I just went to -70 trim and it returned to 15:40
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Probably havenât paid that much attention to the details then. đ
Iâd like to hear what your reasoning is as to why my endurance improved when trimming the aircraft. Maybe I am wrong.
This is what not to do. Most if not all aircraft will require a positive trim of some sort. If youâre trimming in the negative direction, you likely did something wrong.
The only way to test it would be to go on solo and go to cruise, same weather and everything so the results arenât skewed, then see if there is a change between the different trim settings. I notice a change in speed GS in group flights when I set my trim at cruise so Iâd imagine what @DeerCrusher said is true to the sim.
You donât trim just sake of it. Yesterday I flew A330 40000ft at mach. 85. (Recommend. 84) like butter with 0% trim. It was flying flat. There was big tail wind and trim was showing none needed. You check everything before you trim.
I can do anything with the trim since it has no steady state effect while the AP is engaged. Iâm now at +100 with the same fuel burn as 0 and -70 (I also went to -100). Again, I highly encourage you all to test this for yourselves.
When you do these tests, wait a couple minutes for the aircraft to settle back down. No matter what trim setting you go to itâll return to the same fuel burn as before.
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If you could private message me the details of the aircraft, weight, altitude and any other useful information that you are able use to come up with this conclusion. Perhaps thereâs an issue with the sim because this is not suppose to be the case. Thanks for the help into looking into this.
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Honestly I do trim for the sake of it because it wonât effect my performance/range.
Sorry for being off-topic but what is the A380s optimal trim?
(Iâm flying rn and I gotta know haha)