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  #1  
Old 12-31-2018, 10:33 AM
bmarvel's Avatar
bmarvel bmarvel is offline
 
Join Date: Aug 2005
Location: Grand Junction, CO
Posts: 52
Default Skyview pitch trim indication in RV-14

One peculiarity I have not resolved in our -14A is the takeoff pitch trim indication on the Skyview display. Am curious if others have seen the same thing.

As in most airplanes there is a lot more nose up trim tab movement than nose down. To set the Skyview takeoff pitch trim indication one first calibrates the trim servo at both extremes. Then you visually set the tab where you want it for takeoff. One button push later on Skyview establishes a green line to show that position on the display.

I have the longer trim tab pushrod connecting servo to tab and my desired takeoff tab position is very near neutral -- almost in plane with the elevator. But this position is not very far from full nose down trim. It all works fine but looks strange when I set takeoff trim at what appears to be full nose down but isn't.

Have any other Skyview -14 owners run into this?
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Bill Marvel
Grand Junction, CO
RV-8A N751MB -1700 hours, sold
RV-14A N465MM - 418 hours and climbing
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  #2  
Old 12-31-2018, 11:43 AM
Discus2b Discus2b is offline
 
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Location: Willis Gliderport
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So if I understand you correctly, you have concerns with having very little nose down trim available in the TO position, which happens to be trailing inline with the elevator?
Disregarding indications, after setting TO trim, additional trim input moves the tab very little above trailing?

R
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  #3  
Old 12-31-2018, 12:58 PM
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bmarvel bmarvel is offline
 
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To clarify, the takeoff trim tab setting works fine and the airplane flies fine. The problem is that Skyview depicts takeoff trim as very near full nose down. Actual trim tab position for takeoff is not in question -- the Skyview indication of that position is.

In most airplanes I have flown, takeoff trim is shown in the cockpit as roughly half way between full nose up and full nose down with a slight bias toward nose up. In the case of this Skyview display in this airplane, the correct takeoff trim is shown on Skyview as near full nose down trim. This is after following the Skyview setup procedure precisely.

I have plenty of nose up and nose down trim. I'm just wondering if anyone else with Skyview in a -14 model has seen the same thing.
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Bill Marvel
Grand Junction, CO
RV-8A N751MB -1700 hours, sold
RV-14A N465MM - 418 hours and climbing
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  #4  
Old 12-31-2018, 02:22 PM
TimO TimO is offline
 
Join Date: Feb 2005
Location: Wisconsin
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That sounds exactly like mine is on my bar graph display. I take off with 1-2 bars showing on the bottom (so mostly nose down trim), yet the tab itself is nearly neutral, physically. I then get all the nose up trim I need, and as I fly, I'm almost always running still in that 1-2 bar range in cruise. I don't ever feel the need for more nose-down trim, either...but it makes you head scratch a little that the display shows you not far from the limit.

All I can say is, fly on...300+ hours and it's always been this way, and works just fine.
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RV-10 N104CD - Flying 2/2006 - 1375+ hours http://www.MyRV10.com
RV-14 N14YT - Flying 6/2016 - 300+ hours http://www.MyRV14.com
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  #5  
Old 12-31-2018, 03:32 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by bmarvel View Post
The problem is that Skyview depicts takeoff trim as very near full nose down.
This is only the case if you assume that when the indicator marker is at the mid point on the indicator, that the trim tab is in the neutral/in trail position. It is not. The only way that could be the case is if there was an equal amount of up and down travel on the trim tab.
Since that is not the case, your take-off trim setting will be off set towards one end of the indicator.
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Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #6  
Old 12-31-2018, 04:36 PM
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bmarvel bmarvel is offline
 
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Thanks. That is exactly what I wanted to know from someone flying a -14 with Skyview.

It is a little disconcerting when a pilot rated passenger asks why I'm taking off with nearly full nose down trim but that's apparently the way the Skyview system calibrates elevator trim tab position.
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Bill Marvel
Grand Junction, CO
RV-8A N751MB -1700 hours, sold
RV-14A N465MM - 418 hours and climbing
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  #7  
Old 12-31-2018, 04:40 PM
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bmarvel bmarvel is offline
 
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I'll try to cobble up a couple of photos to better show both the trim tab position and the Skyview display when set for takeoff. More RV-14/Skyview owners are going to run into this in the future.

The display shows so far nose down at takeoff trim that it is hard to believe it is correct but apparently is.
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Bill Marvel
Grand Junction, CO
RV-8A N751MB -1700 hours, sold
RV-14A N465MM - 418 hours and climbing
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  #8  
Old 12-31-2018, 06:55 PM
Discus2b Discus2b is offline
 
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Location: Willis Gliderport
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On my -14 ( not 14a), my trim TO setting bar is slightly more than 1/2 below neutral center and bottom. So your concern was indication, not trim travel.
I have been wondering a little myself for over a year.

R
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  #9  
Old 01-01-2019, 10:35 AM
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rwthompson67 rwthompson67 is online now
 
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Location: Springfield, VA
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Is there any guidance on where to set elevator takeoff trim for first flight?
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  #10  
Old 01-01-2019, 11:16 AM
Georges G Georges G is offline
 
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Location: FRANCE
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For my first flight the trim was in trail position.
Indication on my skyview is the same as Bill and Tim.
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