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-   -   Take Off Trim? (https://vansairforce.net/community/showthread.php?t=160510)

Champ 05-16-2018 08:26 PM

Take Off Trim?
 
Wonder what others do with elevator trim setting on take off? I generally take off with no flap and with trim left where it was on last final. With this it seems to fly off when ready and only slight back pressure on the stick and no trim change on climb out. This is when solo and although my battery is in the back and a CS prop I still consider it nose heavy. Also - would you change take off trim with different flap settings and c of g?s?

Veetail88 05-16-2018 08:54 PM

Maybe sloppy on my part, but I never really think about. With the trim on a hat switch on top of the stick, I just adjust the trim when the airplane starts flying. Some times it?s pretty far off, especially if the last time I landed was with a passenger, but the stick pressure is always quite manageable.

KRviator 05-17-2018 12:31 AM

Quote:

Originally Posted by Champ (Post 1260481)
Wonder what others do with elevator trim setting on take off? I generally take off with no flap and with trim left where it was on last final.

I routinely use partial flap for takeoff, but for trim, I do the same and leave it on the 'landing' setting.. Even though I have the trim position showing on SkyView, I don't bother with it until I am established in the climb. Stick forces, even with what I would call quite out of trim, have always been very easily manageable.

AndyRV7 05-17-2018 07:05 AM

Landing setting as well. I just can't turn my head enough to see the trim in my 7. Seems to work. Stick back until full power then let the tail come up, or ease it up.

n816kc 05-17-2018 07:30 AM

neutral trim
 
In my -6 I always set trim to neutral for takeoff. In my plane that results in a positive rate of climb with little/no stick pressure.

The landing trim setting produces a significant pitch up if you remove pressure from the stick on takeoff/climb-out.

I was always taught to keep the plane in trim for the desired flight attitude, you never know when you'll need to remove your hand from the stick for a moment. Stuff happens.

6 Gun 05-17-2018 08:06 AM

Trim
 
I trim for level flight in cruise and never touch it for landing or takeoff !
Bob

Dan Langhout 05-17-2018 08:28 AM

Everything He Said
 
Quote:

Originally Posted by n816kc (Post 1260541)
In my -6 I always set trim to neutral for takeoff. In my plane that results in a positive rate of climb with little/no stick pressure.

The landing trim setting produces a significant pitch up if you remove pressure from the stick on takeoff/climb-out.

I was always taught to keep the plane in trim for the desired flight attitude, you never know when you'll need to remove your hand from the stick for a moment. Stuff happens.

+1

IO-375, Hartzell CS prop, Electric Trim. Neutral trim point displayed on Dynon Skyview EMS display.

nigelspeedy 05-17-2018 08:28 AM

RV-8 TO Trim
 
In my RV-8 I typically end up with a lot of nose up trim on landing so I definitely don't want to take off with it that way. For takeoff solo I set the pitch trim neutral, for takeoff with someone in the back I set it slightly nose down. I leave my flaps down after landing to make it easier to get in and out. So after start I bring the flaps back up and set the trim. I also do a check of trim/flaps/controls in my pre-take off checks.
Cheers
Nige

Flying again! 05-17-2018 08:30 AM

In my -10 I also set the trim at neutral for takeoff. I found out soon after I started flying it during touch and goes that if I left the trim set for landing when the power come up and the flaps retract, there is a strong nose pitch up.

rvbuilder2002 05-17-2018 11:27 AM

If we think about what pitch trim is for (provide a means of trimming the aircraft for a specific speed, flap configuration, and C.G. position), it should quickly become obvious that comparing settings from one RV model to another is pointless. Even comparing two of the same model may not be useful depending on the C.G. that is typical for landing.

I have walked the flight line at fly-ins and have seen trim tab positions (likely still where they were at landing), in positions from one extreme to the other (nose up and nose down).
Sometimes even a lot of nose down (a strong indicator that the airplane was at or maybe even beyond the aft C.G. limit).

For most RV's the ideal trim tab travel is such that allows about 30-35% of the travel to be nose down trim, and the remainder to be nose up trim.
This will allow for being able to trim for a normal approach speed at full flaps at C.G.'s typical for landing (though it still may not be enough when near the fwd end of the C.G. range).

The ideal trim setting for take-off will vary with C.G., but because the control forces on RV's are lighter than many production aircraft, as long as you are close, take-offs are generally not a problem and you can make a small adjustment once stabilized in a climb.
Having said that, my opinion is that every RV should have means of easily determining the pitch trim setting for take-off. Doesn't have to be fancy. For my manual trim RV-6A it is knowing that it is at neutral when the knob is about 1" aft of the fwd limit (no other indicator required).

A take-off with a grossly maladjusted pitch trim (because of having landed with a majorly aft C.G.) can cause quite a surprise, and in some conditions require some major effort on by the pilot to counter act.


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