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  #11  
Old 10-06-2021, 02:01 PM
Mel's Avatar
Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 11,174
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Quote:
Originally Posted by gasman View Post
Van's manual trim...... turn it one way, if the plane doesn't do what you want, turn it the other way.......
The way I remembered the manual trim on my -6 was...Screw the nose down, Unscrew the nose up.
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  #12  
Old 10-06-2021, 02:16 PM
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wcalvert wcalvert is offline
 
Join Date: Jan 2019
Location: Anacortes Wa
Posts: 298
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Ok, I apologize for my snarky remark! I've not seen an aircraft with a trim switch on the dash, so it didn't seem possible you could fly a stick with the trim button running backwards... my mistake.

And a great question for the OP to ask. It was the only thing on my Certificate inspection that the DAR was really serious about. Guess it must happen often.

Fly Good
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  #13  
Old 10-06-2021, 03:37 PM
JwWright57 JwWright57 is offline
 
Join Date: Dec 2016
Location: Charlotte, NC
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Quote:
Originally Posted by amekler View Post
I'm not sure my trim is correctly set up. I followed the procedure in the setup for full up full down and takeoff
it said calibration accepted but I see no markings on the trim indicator.
I'm also confused when you engage nose up which way should the tab move?
any help pictures appreciated.
Thanks,
Alan
N603NH RV-12 almost done
To answer your original question, during setup you measure 2 inches up if I remember right. And that is your takeoff trim line. There is a step for it in the production acceptable process
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  #14  
Old 10-07-2021, 02:12 AM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
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Default Expanded Scale for Trim Indicator

I have set up my trim indicator as an expanded scale. Instead of showing the entire range of trim servo, I have set the end points to show only the portion of the trim corresponding to the flight envelope. End points on the scale are slightly greater than is experienced in flight. This allows a more meaningful and intuitive view of the usable window of trim movement.

Why show movement of trim that is not ever going to be used in flight? This is similar reasoning as used on an analog Volt Meter where the user selects the appropriate scale so readings are more accurate and easier to interpret. Why measure 5 volts on a 500 volt scale?

I recently had my pitot tube break in flight causing very erratic airspeed readings that were meaningless. When I slowed for landing, I set the trim to 1/8Ē from top of scale and I knew airspeed would be ~63 mph (55 knots) hands-off at idle power setting.

The photo below shows the Takeoff, Cruise, and Landing positions for trim. Because the scale is expanded, the motion of the indicator is more sensitive and allows more accurate positioning especially for takeoff.
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  #15  
Old 10-07-2021, 07:54 AM
amekler amekler is offline
 
Join Date: Aug 2009
Location: Gilford,NH
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So I'm still trying to figure this out
here are 2 photos
one with the stick full forward and trim all the way down and the other with the stick full back and the trim all the way up
Alan
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Last edited by amekler : 10-07-2021 at 08:07 AM. Reason: no photos
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  #16  
Old 10-07-2021, 08:18 AM
sailvi767 sailvi767 is offline
 
Join Date: Sep 2010
Location: Charlotte NC
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I donít know anything about the RV12 trim system. If however itís conventional in the first pic the trim is full nose up. In the second pic the trim is nose down.
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  #17  
Old 10-07-2021, 08:51 AM
N8DAV8R N8DAV8R is offline
 
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Location: Salida, Ca
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Quote:
Originally Posted by sailvi767 View Post
I don’t know anything about the RV12 trim system. If however it’s conventional in the first pic the trim is full nose up. In the second pic the trim is nose down.
The RV-12 has a stabilator with an anti-servo tab. Being familiar with the motion of an AST in contrast to a typical elevator and trim tab is important to answering the question, especially based on photos. An AST moves consistently in the same direction throughout the travel of the stab in order to dampen control surface forces. Trim makes a relative change. Unless you really have calibrated eyeballs, it's hard to determine this with photos of the two extreme stick positions.

The AST is moving in the correct direction. It would be hard to build the 12 the wrong way with respect to the AST. Need to see the relative movement of the AST with the stick in a constant position and trim input is given to determine if trim direction is correct.
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  #18  
Old 10-07-2021, 05:24 PM
amekler amekler is offline
 
Join Date: Aug 2009
Location: Gilford,NH
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problem solved
I took a look at an RV-12 LSA with the stick neutral up trim causes the tab to move down and vice versa. Mine is backwards and I switched pins 4 and 5 and now it behaves correctly.
Alan
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  #19  
Old 10-08-2021, 08:52 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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Funny story: I once got some instruction in a Yak-52 from Sergei Boriak, world champion aerobatic pilot. After all that experience he was still using his hands to mimic the trim tabs to figure out which way they should be bent.
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