Position of Trim Tab (Take off)

[KevinS]

Hey everyone.

My 170 currently does not have a "mark" for the position of the trim tab wheel for T/O. My question is on takeoff, should the plane be trimmed neutral, tail up or tail down?

Thanks once again.

Kevin

[Bruce Fenstermacher]

Well Kevin I would think you would want the trim positioned so there is no pressure at the attitude you want to climb at. If your plane had the marks you would probably find this spot would be in the range of the markings which is what the marks are for.

You are probably used to looking down at the trim and eye ball that it is where is should be per your experience or there about and this position will most likely be where it was left for your last landing. If your plane is loaded the same as the last landing this position will be close for the takeoff.

Let me say this another way. The marks are only there as a reference that would indicate that under normal conditions and loading if the trim is between the marks you will be close to in trim for takeoff. Want a surprise try taking off with your trim well forward. Want an even bigger surprised takeoff with your trim way back. <PLEASE don't actually try this intentionally.

[3958v]

Bruce I totaly disagree with your position of no doing that intentionally. You probablly should do it intentionally with a flight instructor so you recognize what it feels like. I did it accidently once and it is very disconcerting and I know of a fatal accident recently on take off in another plane where the trim was found in the full up position. Its certainly a situation all pilots should be trained to recognize and deal with. Bill K

[Robert Eilers]

Kevin - while on the ground position the trim wheel so that the elevator trim tab is neutral - in line with the elevator. This trim position should give you a good starting point.

[Bruce Fenstermacher]

Bruce I totaly disagree with your position of no doing that intentionally. You probablly should do it intentionally with a flight instructor so you recognize what it feels like. I did it accidently once and it is very disconcerting and I know of a fatal accident recently on take off in another plane where the trim was found in the full up position. Its certainly a situation all pilots should be trained to recognize and deal with. Bill K

Bill I was being cautious about suggesting someone try this as I don't want you to know of another accident recently where the trim was found in the full up position.

[jrenwick]

Bruce I totaly disagree with your position of no doing that intentionally. You probablly should do it intentionally with a flight instructor so you recognize what it feels like. I did it accidently once and it is very disconcerting and I know of a fatal accident recently on take off in another plane where the trim was found in the full up position. Its certainly a situation all pilots should be trained to recognize and deal with. Bill K

Normally an instructor will demonstrate something like this at altitude sufficient to recover above 1500' AGL, as a "trim stall." You simulate a glide down final approach, and set full nose-up trim. Then you simulate a go-around, and notice that the airplane may require aggressive nose-down force on the elevator control just to prevent a stall.

This can be an especially dangerous situation in a Super Cub with a lot of excess power and with the horizontal stabilizer being used for trim. There have been fatalities due to it.

I sure like the new web site!!!!!

[alaskan99669]

Hey everyone.

My 170 currently does not have a "mark" for the position of the trim tab wheel for T/O. My question is on takeoff, should the plane be trimmed neutral, tail up or tail down?

Here's a picture of where mine is on take-off and for most loads that is trimmed at full power for 60 MPH with 20 deg. flaps, 70 MPH with 10 deg. flaps, and 80 MPH for zero flaps.

HandleAfter.jpg

I've bought new decals, but have not put them on yet. You can still order them from several sources online:

TrimTabDecals.jpg

[GAHorn]

The trim tab should be NEUTRAL for takeoff, and the indicator should agree by being placed in the middle of the takeoff range. The pilot should CONFIRM the indicator and the tab agree with each other during the preflight inspection. (With the indicator in the middle of the takeoff position, the tab itself should be exactly streamlined with the elevator.)