Elevator up & down travel

[thomasjones42]

I have so far been unable to get elevator travel any place close to the angles called out in the plans. In trying to gain more upward travel I've ground the elevator horn down to the edge of the head of a trial bolt I placed in the horn. My upward elevator travel is now limited by the bolt head hitting the bottom of T08-13. I'm still only getting about 17 degrees up elevator from the level on the horizontal tail (or 163 degrees) if measured as the plans show. By the same token, downward travel is about 30 degrees from the neutral (approximate chord line) versus 25 degrees. I could correct the down elevator travel with a small plate on the back of the aft horizontal tail spar but given the bolt head conflict in upward travel (and likely the elevator push rod conflict) I'm out of ideas and beginning to wonder if my elevator horn may not be welded to the elevator connecting tube at an incorrect angle. An A&P I had look at the situation thought this unlikely given it was probably welded on a jig but if the horn were rotated a degree or a few forward toward the front of the airplane, both the up travel and down travel problems would be mitigated. Other than heating and bending the horn or buying a new one and betting the angle will be different, I don't know how to make this work. If I bought a new horn, I do not look forward to taking the necessary rivets out as I cannot get behind them to keep them from spinning. I'm not entirely comfortable with the amount of grinding I've done on the horn in terms of potentially weakening it and I'm very uncomfortable with having less than the specified up elevator travel. I've taken a number of pictures and emailed Kerry so if he has a solution I'll post it but in the mean time I'm wondering if anyone else has encountered a similar problem, if so what did they do about it and does anyone have a thought about where I may have gone wrong.

Tom Jones
ONEX Kit #133

[gammaxy]

I had similar challenges with my Sonex, but I think my problem was reversed. I ground a small amount of material for the bolt head to clear, but I ended up adding a spacer to the back of the spar to prevent me from having too much up elevator.

One option I considered was removing the elevator horn by drilling the elevator root ribs out (I believe this might avoid your spinning heads problem until you can get to the back side). Then fabricate new root ribs and attach the horn rotated on the new ribs by a few degrees.

[Fastcapy]

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[thomasjones42]

Can you give me the location and name of your FAA inspector?

Tom Jones
ONEX Kit #133

[Stogie6]

I, TOO, AM HAVING THE SAME PROBLEM. MEASURING BY BOTH THE ARC METHOD AND THE CENTER LINE I CAN ONLY GET AT MOST ABOUT 16 DEGREES. BEING A LONG TIME TAILWHEEL PILOT, I WOULD LIKE THE FULL ELEVATOR TRAVEL. NOT THE "IT WILL BE OK" MAKES ME WONDER IF THE CONTROL HORN IS NOT WELDED AT THE RIGHT ANGLE. MY DOWN TRAVEL IS OVER 30 DEGREES I HAVE HAD THE SAME PROBLEM BUILDING RVs BUT HAVE BEEN ABLE TO WORK THEM OUT. THIS ONE HAS ME STUMPED.

IF YOU REPLY TO THIS PLEASE USE MY EMAIL ADDRESS
hangar50r@gmail.com


GOOD LUCK
TED F, JONES

[Stogie6]

For those who answer the elevator up and down travel question above from Ted F. Jones, he is my father and building patner. I am definitely learning from the master on this one!

[Sonex1517]

I am interested in this one myself - facing similar challenges

Robbie

[tonyr]

During the construction of my Sonex, I was aware that elevator travel would be an issue from reading various web site logs and speaking with local builders.

I was careful with placement of the horizontal stab actually placing it in position with the elevator attached and checking the range of movement with the elevator pushrod attached to the stick frame and elevator.
There were contact problems with the vertical stabilizer and elevator control horn, also I reversed a couple of bolts on the vertical stab rear spar.
I had to grind the last former hole for the pushrod.
I ground away the vertical stab skin to make room for the control horn tube with up elevator.
I still didn't quite have the required range of movement.
I couldn't/wouldn't make any changes to the stick or stick frame configuration, so the pushrod travel was a "fixed" range.
Moving the horizontal stab fore and aft affects how much "up" vs how much "down" you end up with if everything else remains the same...
If you have too much down or too much up, playing with the horizontal stab position can help before you drill the mount holes.
Don't drill the pushrod joiners (In Sonex) until you have that bit sorted. Also make sure its securely clamped if you do have everything in place in the elevator circuit.
After all this I still didn't quite have enough travel in either direction..

The final piece of work that gave the deflection range specified was to re-make the elevator root ribs (as mentioned above in this thread) and re-attach the elevator control horn as far forward as possible on the root ribs. It was a pain to drill out and remake new root ribs from scratch over a wood form, (mine were kit formed)
I probably violated the edge distances a little on the front row of rivets attaching the control horn. Maybe < 1/8" instead of 1/4"!
The steel edge of the control horn ended up a bit further forward than the forward edge of the root rib. I had previously mounted them flush with the edge bend on the root rib.
I did have to do more grinding of the control horn and vertical stab to get the clearances..

However by positioning the control horn as close as possible to the hinge line I achieved the desired range of elevator travel.

If the control horn is too far away from the hinge line, you will not get the elevator deflecting the desired amount for the fixed range of pushrod movement.

Hope this helps.. its a multidimensional puzzle!

Cheers
Tony

[thomasjones42]

I am interested in this one myself - facing similar challenges

Robbie

Robbie,
For what it's worth, I tried most of the things that Tony R describes and I think his comments are spot on. On my ONEX kit however; the elevator root ribs and the horn were both pilot drilled so moving the horn forward on the root ribs wasn't really an option although I now believe that is one of the major keys to getting to the prescribed up travel. The four holes for mounting the horizontal stabilizer and the corresponding holes in the upper fuselage stringers were also pilot drilled so moving the stabilizer forward was not an option either. As I told you last weekend I became uncomfortable with the amount of grinding and bending I had done on the original horn and ordered a new one and new root ribs. When I recieved my second set of root ribs (which I did not use) and new rudder horn, I noticed that these new root ribs were not pilot drilled. If I were to do it again I would either buy or make a second set of root ribs and as a trial, try mounting the horn slightly forward of the leading edge of the root rib sacrificing rivet edge distance and see what that gave me for up elevator. In retrospect I think that alone might have solved my problem. Again, for what it's worth.

Tom Jones
ONEX kit 133

[Sonex1517]

Thanks Tom!

Great meeting you this weekend at the fly in - thanks for making the journey!


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved