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01-07-2015, 11:59 PM
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Join Date: Jun 2009
Location: Mesa, AZ
Posts: 242
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RV-6A - what I remember
Quote:
Originally Posted by WingsOnWheels
The problem i have with the forward travel of the pushrod is that the rod end contacts the inside of the yoke on the control stick weldment. Ken said i can trim a little material away from that area for clearance. That is limiting my control adjustment. A little more tweaking it may work out, but it will.still be very close.
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Collin - I had to go back out and review my forward elevator tube travel to remember some details. 1) I also filed away a tad from the control tube elevator yoke (fwd end of elevator tube) mainly because the straight and very sharp edge would indent the top of the rod-end. Minor clearance added but any contact is smoother now. 2) the elevator tube under the seat pan tunnel cover is very close to touching, 1/16" clearance but the motion on the tube is almost vertical (not horizontal) at that point of stick max fwd. 3) without the control stick boot retainer, MY control stick moves forward further, ALLOWING the tube to come up that high. (Normally this would be restricted by the elevator stops, or the boot retainer. My elevator is currently OFF.) 4) I vaguely remember that the control stick was supposed to be (5degs ?) forward and not absolutely vertical when setting up the travel. Will research the manual for that detail.
I recently found that the rivets on the aft end of the elevator tube snagged the edge of the aft baggage compartment bulkhead hole. Discovered while reviewing the pitch servo motion. Had to adjust the spacers on the bellcrank, and will file the hole edges slightly.
__________________
gary
RV-6A QB Tip-Up, 1st Flight 3/18/17 
O-360-J2A (modified & F/I), Sensenich FP (cruise)
VP-X Sport, Dynon SkyView, VFR day
(FFZ) Mesa, AZ - N234GB -
www.mykitlog.com/garyc
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01-08-2015, 12:49 AM
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Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,005
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If all else has been tried...
RV 7 & 9 models have a raised cover in the centre tunnel area. What say you copy something similar to gain your needed floor clearance? Don't make it too high if you have manual flaps though.
__________________
Ralph
built a few RVs, rebuilt a few more, hot rodded some, & maintained/updated a bunch more
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01-08-2015, 05:17 AM
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Join Date: Mar 2009
Location: Plano, TX
Posts: 2,090
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Quote:
Originally Posted by RViter
Collin - I had to go back out and review my forward elevator tube travel to remember some details. 1) I also filed away a tad from the control tube elevator yoke (fwd end of elevator tube) mainly because the straight and very sharp edge would indent the top of the rod-end. Minor clearance added but any contact is smoother now. 2) the elevator tube under the seat pan tunnel cover is very close to touching, 1/16" clearance but the motion on the tube is almost vertical (not horizontal) at that point of stick max fwd. 3) without the control stick boot retainer, MY control stick moves forward further, ALLOWING the tube to come up that high. (Normally this would be restricted by the elevator stops, or the boot retainer. My elevator is currently OFF.) 4) I vaguely remember that the control stick was supposed to be (5degs ?) forward and not absolutely vertical when setting up the travel. Will research the manual for that detail.
I recently found that the rivets on the aft end of the elevator tube snagged the edge of the aft baggage compartment bulkhead hole. Discovered while reviewing the pitch servo motion. Had to adjust the spacers on the bellcrank, and will file the hole edges slightly.
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The clearance you to the floor sounds pretty similar to mine. Based on the responses to this thread it seems I am not the only one with this issue and it just needs to be worked out. I was concerned that I had made a mess of something down the line or it was related to my change to the RV-7 Tail. I can buy myself another 1/8" of clearence if I buy new F-633 L&R (the brackets that connect the weldments to F-604) and drill the holes closer to the top.
__________________
Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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01-08-2015, 05:24 AM
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Join Date: Mar 2009
Location: Plano, TX
Posts: 2,090
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Quote:
Originally Posted by rvbuilder2002
This starts to become a problem when you adjust the control sticks to be more vertical at neutral... vs angled fwd as they are supposed to be. You are inducing this problem with your adjustments compensating for the other problem.
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I agree completly, but at this point I don't see any other options. If I set the control stick neutral to 5 Degrees forward, the pushrod doesn't clear the floor at full forward stick travel. I think the reality is that the design max down limit for the elevator (while also having max up) is not possible without modification to the control. Looking at the plans even, the geometry doesn't work out. It is unlikely that full down elevator will be used by 99% of RV'rs, The better option may be for me to limit down travel closer to Min than Max. That may eliminate the need to make modifications.
__________________
Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
Last edited by WingsOnWheels : 01-08-2015 at 05:44 AM.
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01-08-2015, 11:03 AM
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Join Date: Mar 2005
Location: Molalla, Oregon (KOL05)
Posts: 529
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Quote:
Originally Posted by WingsOnWheels
The stops are all in place. The down stop is about .5 degrees short of Max, and the up stop is about 2 degrees short of Max.
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Chapter 15 gives the travel limits of Max 30/25 (Up/Down) and Min 25/20 (Up/Down). There are no issues with going with the minimum limits and it aids in avoiding control components interfering with structure. You will typically only hit these deflections when taxiing and it could be a WILD ride if you hit them in flight.
Try limiting the UP stop by a few degrees and see if that eliminates the interference issue. It's pretty easy to simulate this.
__________________
Joe Blank
RV-6
IO-320-D1A
Advanced Flight Systems
Van's Aircraft Inc. Technical Support-Retired
EAA Tech Counselor & Flight Advisor
www.westcoastravens.com
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01-08-2015, 12:33 PM
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Join Date: Jul 2013
Location: US
Posts: 2,251
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Quote:
Originally Posted by WingsOnWheels
I agree completly, but at this point I don't see any other options. If I set the control stick neutral to 5 Degrees forward, the pushrod doesn't clear the floor at full forward stick travel. I think the reality is that the design max down limit for the elevator (while also having max up) is not possible without modification to the control. Looking at the plans even, the geometry doesn't work out. It is unlikely that full down elevator will be used by 99% of RV'rs, The better option may be for me to limit down travel closer to Min than Max. That may eliminate the need to make modifications.
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Something must not be right with the entire assembly...there are too many -6s flying which don't have this problem.
Is the bellcrank installed correctly, right side up? Is it the correct control stick weldment? Etc.
Find the root cause of this interference...the plane certainly wasn't designed to be as you describe.
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01-08-2015, 04:13 PM
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Join Date: Mar 2009
Location: Plano, TX
Posts: 2,090
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Quote:
Originally Posted by RV7A Flyer
Something must not be right with the entire assembly...there are too many -6s flying which don't have this problem.
Is the bellcrank installed correctly, right side up? Is it the correct control stick weldment? Etc.
Find the root cause of this interference...the plane certainly wasn't designed to be as you describe.
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I will check some more measuements on the weldment. I did check that the horn was the right length, but that was it. The bellcrank is positioned per plans. Ken mentioned that filing the yoke a bit is a common mod. I think i need to adjust the down stop a bit. I would rather limit down travel than up if i have to pick one.
__________________
Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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01-08-2015, 06:33 PM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Quote:
Originally Posted by RV7A Flyer
Something must not be right with the entire assembly...there are too many -6s flying which don't have this problem.
Is the bellcrank installed correctly, right side up? Is it the correct control stick weldment? Etc.
Find the root cause of this interference...the plane certainly wasn't designed to be as you describe.
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Well, yes and no. Every 6 is different, not like the pre punched kits. I built my wings but was one of the early QB fuselages. I had many discrepancies from the plans to the actual built fuselage, especially in and between the area of the center section and baggage bulkhead. I had a lot of compromises with rear baggage side panels, wing sweep, etc....but she still flies fast and true. A credit to the conservative design of the product.
It does not take a lot of change in this area to start introducing problems. However, it all can be worked through, one way or another as evidence by the shear number flying. Some of us just had or have a little more fiddling to do, and this area seems to be one of them, at least it was for me.
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
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01-09-2015, 04:46 AM
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Join Date: Mar 2009
Location: Plano, TX
Posts: 2,090
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After messing with everything again last night it looks like I can make it work but I would have to limit elevator travel to minimum both up and down (25 / 20) rather than what I have right now (27.5 / 24.8). With this being an A model, I was hoping to maximize up travel so I could hold the nose off as long as possible.
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.
And in case anyone is wondering, I don't believe any of this was caused by switching to the RV-7 tail. The elevator control horns for the RV-7 are an RV-6 part number and at quick check the measurements appear to match the RV-6 plans.
__________________
Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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01-09-2015, 02:07 PM
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Join Date: Jul 2009
Location: England
Posts: 470
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Very timely Colin ... I am getting close to do the push-rod install and look forward to hear what you find out ...
Good luck !
__________________
Jan
Slooow RV6, no hole, builder in UK
Paid up for 2015 ...
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