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Using Elevator Trim Indicator to Full Advantage

Piper J3

Piper J3

Well Known Member
Until recently I have been using the elevator trim indicator on the D-180 to set and verify only takeoff trim position. Once airborne I would make trim adjustment for cruise and decent strictly by feel, which required many small, step adjustments to reach hands-off pitch stability.

I have made mental note of where trim indicator needs to be to satisfy cruise and power-off glide with full flaps deployed. Now when I change from climb to cruise and from cruise to decent I can quickly attain stabilized flight in pitch by setting the elevator trim by visual reference to the trim indicator. By roughing-in the trim setting visually I can attain desired pitch stability quickly with just a few small step adjustments and thus minimize workload.

So for what its worth (and maybe I’m just late to the party as usual) I thought I’d pass along this revelation as I gracefully age in my love of flying…

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Based on the location you are indication for cruise trim and the position of your take-off trim indicator, I would say that your indication is not properly calibrated.
The take-off indicator is normally about 1/8" below the mid point mark, and cruise position is typically about 1/4 of the way up from the bottom.
 
Ditto what was said above. I use the trim indicator bar to initially set my trim for takeoff. After that, I virtually never look at the trim indicator again during flight. I suggest that one should be trimming in-flight to remove control pressures from the stick -- not pre-setting the trim for a future flight condition or "flying " the plane using the trim alone. During my application of flaps, I position the flap handle and then initially adjust the trim by pushing the trim switch and counting a suitable number of seconds - then fine-tune it if needed to achieve the desired airspeed and control pressure. Works for me!
 
As noted, the cruise position will vary with how much and where you are carrying passengers or baggage, as well as airspeed.
 
DHeal said:
Ditto what was said above. I use the trim indicator bar to initially set my trim for takeoff. After that, I virtually never look at the trim indicator again during flight. I suggest that one should be trimming in-flight to remove control pressures from the stick -- not pre-setting the trim for a future flight condition or "flying " the plane using the trim alone. During my application of flaps, I position the flap handle and then initially adjust the trim by pushing the trim switch and counting a suitable number of seconds - then fine-tune it if needed to achieve the desired airspeed and control pressure. Works for me!
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I generally agree with that too. Would add that after putting in the first setting of flaps in the pattern I move the trim to the takeoff position which usually fully removes pressure from the stick - if I have to do a go around, I want the trim setting for takeoff to eliminate the need to adjust it when I'm focused on climbing out.
 
PilotBrent said:
I generally agree with that too. Would add that after putting in the first setting of flaps in the pattern I move the trim to the takeoff position which usually fully removes pressure from the stick - if I have to do a go around, I want the trim setting for takeoff to eliminate the need to adjust it when I'm focused on climbing out.
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Ditto...if something happens, I want to be set up for go around. Full throttle drop one notch of flaps; eyes on my route out!!!
 
Phantom30 said:
Ditto...if something happens, I want to be set up for go around. Full throttle drop one notch of flaps; eyes on my route out!!!
Click to expand...


Does that result in being out of trim with landing flap and approach speed? If so, are you pushing or pulling on approach?
 
I would add that the trim setting for take off will vary considerably with CG. On big airplanes there is a "green band" which covers the full CG range. if you are in that band your stick forces will be acceptable if your CG is anywhere within the envelope. If you set your trim based on a chart in the AFM you will be bang on at V2+something, the all engine safety speed. So there isn't one setting that is good for all conditions.

The trim should be set to trim the airplane at your best climb speed, although again it will vary with CG somewhat so some adjustment will be required. But for takeoff, especially with a tandem RV (4 or 8) where the CG variation is large, the takeoff trim setting will only be a guideline.
 
sblack said:
Does that result in being out of trim with landing flap and approach speed? If so, are you pushing or pulling on approach?
Click to expand...

Hasn't caused me any problems.. I find the control force so light..not an issue. Take-off trim setting has worked fine in all cg configurations for me.

The -12 is about as easy to fly as any plane.
 
I didn?t mean to open a can of worms when I started this thread. Scott is correct that my trim indicator shows different from Van?s setup instructions. I set my end points for the trim indicator short of the true end of motion. That way I get an expanded scale and finer resolution of the trim indicator for only the range of motion incurred for normal flight conditions and not end of scale where trim is never used. This explains why my takeoff and cruise indicated positions are depicted differently.

The positions shown in my photo allow rapid initial trim adjustment for all three phases of flight. Changes in CG and gross weight have very little affect and are easily accommodated with a few small bumps of the trim switch. Very happy with this setup?
 
Phantom30 said:
Hasn't caused me any problems.. I find the control force so light..not an issue. .
Click to expand...


If the control force is light then what is the point of flying the approach out of trim for a case that you might encounter once in 50 landings if that case is easy to fly in landing trim anyway?
 
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