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  #31  
Old 01-09-2015, 02:37 PM
BillL BillL is offline
 
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Location: Central IL
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Default I miss real drawings.

Quote:
Originally Posted by WingsOnWheels View Post
After messing with everything again last night < snip >
Before I make any changes though I am going to find the root cause of my issue. Also last night, I pulled out the plans and drew up the basic floor, F-604 and F-605 structure in CAD. I also added all the geometry for the control system components from the stick to the elevator all exactly matching the plans. My next step is to model the elevator travel I have on the plane and see where my results differ from the CAD model. Assuming there is a delta, I'll start to measure every component until I figure out what happened.

< snip >.
Yes -this is what I do from time to time to really understand what is going on and why. Having real dimensions, lengths, center, clearance, and angles is invaluable for really building an RV. I do it in pencil, but, the result and understanding is the same.

I miss real drawings.

Please share your result, it is an interesting issue.
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  #32  
Old 01-09-2015, 10:12 PM
WingsOnWheels WingsOnWheels is offline
 
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Location: Plano, TX
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Ok, I have put all the required structure and control system parts into CAD for analysis. The data I loaded is all directly from the most current set of plans I have. I have not compared it to the very old set I also have, but some of those drawings do have revisions in the current version.

Here is a overview of the drawing I made. For control neutral, I assumed a 5 degree forward cant of the control sticks, and that seems reasonable. I did not include any aileron control parts on the drawing, so that is why the control stick look funny. The square at F-605 represents the per-plans vertical dimensions of the pushrod cutout.

The fuchsia lines represent the control system with Max (25 Deg) down elevator deflection.



The area circled above is shown in more detail in this image. The green line is the top of the seat rib. The fuchsia lines are the pushrod width and centerline. You can see that the pushrod is breaking the plane of the seat pan/seat rib top.



Here is the system again with Max (30 deg) up elevator. This is based on the same neutral point as the down elevator example.



And a closeup of the highlighted area.



You can see that the control rod is one again interfering with the seat pan. However, less so than the down travel limit. For max Up elevator the overlap is 0.063". For max down elevator it is 0.127". Changes to the neutral point could improve one or the other, but not both.

My conclusion is that it is not possible to reach max up and down elevator deflection with the RV-6 control geometry per plans.

The next step is to see what is the max possible deflection without the noted interference.

It seems where I went wrong was to make my elevator stops before completely rigging the elevator controls. I should have left the stops long and trimmed them once I had everything set up and could make appropriate adjustments. For my RV, I need to make new up and down stops to something less than max deflection, but no less than minimum. Based on what I have seen already I think I will have to remove around 5-10 degrees of total elevator travel, but that is just a guess at this point.

I would really like to know how much up/down travel some completed RV-6s have for comparison purposes. Are builders generally ending up with something close to Minimums?
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  #33  
Old 01-09-2015, 11:27 PM
chriscencula chriscencula is offline
 
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Location: Northern California
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Default

Was just about to cut the hole in F-606, good timing.
Very interested to hear what travel others have on their flying rv-6's
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  #34  
Old 01-10-2015, 08:48 AM
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JonJay JonJay is offline
 
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25/30 on mine
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  #35  
Old 01-10-2015, 10:33 AM
WingsOnWheels WingsOnWheels is offline
 
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Quote:
Originally Posted by JonJay View Post
25/30 on mine
Thats very interesting. I wonder how your installation differs. Did you have to remove any material for clearance at the forward rod end. Id really like to know how much clearance you have from the pushrod to the floor, and how far from the top of f-604 to the top of f-633 ( the pivot blocks for the control weldment).
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  #36  
Old 01-10-2015, 12:17 PM
WingsOnWheels WingsOnWheels is offline
 
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I have been trading pictures with Don in Fl, he is getting near full up/down travel as well with no issues. From the pictures, his setup look the same as mine.

Back to the drawing board again. Im not sure what is different.
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  #37  
Old 01-10-2015, 03:37 PM
BillL BillL is offline
 
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Location: Central IL
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Is the stick pivot the correct height above the bottom of the spar?
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RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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  #38  
Old 01-10-2015, 03:50 PM
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JonJay JonJay is offline
 
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Mine looks exactly like what is shown on dwg. #40 .
Clearance to the seat pan is not an issue, not really even close. Weird.
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  #39  
Old 01-10-2015, 03:59 PM
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Mel Mel is online now
 
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Is it possible that your seat ribs are from an RV-7?
The seat pans were lowered for the -7 and -9 to increase headroom.
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  #40  
Old 01-10-2015, 05:09 PM
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az_gila az_gila is offline
 
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Question

Colin,

You used 5 degrees for the stick angle, but as I read it, the easier method is to make the drive horn (Detail A in the picture) vertical when the system is in neutral position.

This is what the plans seem to show.



If you change the stick neutral angle, does it help? My scan is different from the green neutral lines in your CAD drawing.
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Last edited by az_gila : 01-10-2015 at 08:21 PM.
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