Waiex-B mixer and rudder install - stop not being hit

[sjakulski]

So, after installing the Waiex mixer and cabling up the rudder I find there is not enough throw in the mixer to allow the rudder to hit the rudder stops. My rudder deflection is about an 1/8 inch shy of hitting the rudder stop on each side. Anyone else experience that?

[GordonTurner]

Have you checked throws on the ruddervators? First, I think they are more critical, but more importantly they are adjustable. If they are all meeting their target angular throws then perhaps check the dimensions of the rudder horn, particularly how far out from the hinge line are the cable connections. If the Tailwheel or nosewheel is installed and connected that may be limiting the throw as well.

Gordon

[Rynoth]

You need to determine what is causing the early stop and solve it. If I recall, I had to bend (concave) a couple of the washers that hold the ruddervator pushrods to the mixer, otherwise they were binding when pitching up and applying full rudder. You definitely want full rudder deflection to the stops at all pitch inputs.

If your rudder pedals are hitting the firewall before the rudder hits the stop, you'll need to shorten the length of cable between the pedals and the mixer. This is done by drilling different holes into the rudder pedal adjustment plates.

[sjakulski]

Have you checked throws on the ruddervators? First, I think they are more critical, but more importantly they are adjustable. If they are all meeting their target angular throws then perhaps check the dimensions of the rudder horn, particularly how far out from the hinge line are the cable connections. If the Tailwheel or nosewheel is installed and connected that may be limiting the throw as well.

Gordon

Ruddervators , etc., are not connected yet. only the aft cables from the rudder is connected to the mixer. I would have to tear apart my already painted rudder to redo the horns to move attachments point closer in than where plans dictated but not gonna do that at this point. Maybe later.

[sjakulski]

You need to determine what is causing the early stop and solve it. If I recall, I had to bend (concave) a couple of the washers that hold the ruddervator pushrods to the mixer, otherwise they were binding when pitching up and applying full rudder. You definitely want full rudder deflection to the stops at all pitch inputs.

If your rudder pedals are hitting the firewall before the rudder hits the stop, you'll need to shorten the length of cable between the pedals and the mixer. This is done by drilling different holes into the rudder pedal adjustment plates.

Nothing connected yet other than the aft rudder cables to the mixer.

[sjakulski]

So, after installing the Waiex mixer and cabling up the rudder I find there is not enough throw in the mixer to allow the rudder to hit the rudder stops. My rudder deflection is about an 1/8 inch shy of hitting the rudder stop on each side. Anyone else experience that?

After much study I have determined that the problem is the mixer itself. The top plate (used to attached the ruddervator rods) is striking the mixer shaft before the rudder cables can complete the throw. That top attach plate needs to have about an 1/8 inch trimmed from its width.

[sjakulski]

So, after installing the Waiex mixer and cabling up the rudder I find there is not enough throw in the mixer to allow the rudder to hit the rudder stops. My rudder deflection is about an 1/8 inch shy of hitting the rudder stop on each side. Anyone else experience that?

After much study I have determined that the problem is the mixer itself. The top plate (used to attached the ruddervator rods) is striking the mixer shaft before the rudder cables can complete the throw. That top attach plate needs to have about an 1/8 inch trimmed from its width.

Specifically, the Bolts and fender washers used to attach the ruddervators and idler rods interfere with each other as the rudder is deflected, preventing full throw of the rudder. While the WXB-C01 plan diagram shows the most inward bolt hole used for the ruddervator rods there is also an outer bolt hole, never referenced. Wondering if these holes have to be used instead? It would prevent the interference but is not what the plans call out to use (like the plans are not mostly mistakes anyway…). What do others recall? Using the outer hole will mess up the skin opening for the rod big time, I’m sure, if that is the solution…

[sjakulski]

So, after installing the Waiex mixer and cabling up the rudder I find there is not enough throw in the mixer to allow the rudder to hit the rudder stops. My rudder deflection is about an 1/8 inch shy of hitting the rudder stop on each side. Anyone else experience that?

After much study I have determined that the problem is the mixer itself. The top plate (used to attached the ruddervator rods) is striking the mixer shaft before the rudder cables can complete the throw. That top attach plate needs to have about an 1/8 inch trimmed from its width.

Specifically, the Bolts and fender washers used to attach the ruddervators and idler rods interfere with each other as the rudder is deflected, preventing full throw of the rudder. While the WXB-C01 plan diagram shows the most inward bolt hole used for the ruddervator rods there is also an outer bolt hole, never referenced. Wondering if these holes have to be used instead? It would prevent the interference but is not what the plans call out to use (like the plans are not mostly mistakes anyway…). What do others recall? Using the outer hole will mess up the skin opening for the rod big time, I’m sure, if that is the solution…

Sonex says some have reported this issue and claim it depends on the rods provided (?). They suggest bending the offending fender washers fore and aft and tightening the nut to prevent the washer from moving/rotating such that it would not cause the interference again. Well, these bolts use a castle nut with pin. I do not like that solution at all. I do not see any combination of washers allowing one to tighten the castle nut to a perfect tight position while allowing one to insert the pin, and guarantee that the bolt and fender washer will not rotate during use/flight. I tried using a smaller fender washer and drilling it out to bolt size. Still interfered . Also it seems the dimensions/length of the forward rod once attached with its bolt and nut just simply disallow use of the inner holes for the stabilator rods while not causing interference (that is, full pivot). I placed the stabilator rods, therefore, in the outer holes (Sonex says these are for the Onex). The stabilator deflection (10 degrees, etc) using these mixer holes seems to still be obtained… Any thoughts, or others that have experienced this issue?

[Bryan Cotton]

Do you have pictures? If the fender washer hits the rod end, like mine did, you can cup the fender washer. Put a bolt in it, find a socket that matches the OD of the washer, and press the bolt so it pushes the assembly into the washer. Afterwards the washer is cup shaped. Gives clearance on the rod ends, but will retain the rod end if it fails.

Edit:


From this thread:
viewtopic.php?f=3&t=396

Page 5 this comes up. I discussed on my build thread too.

[sjakulski]

Do you have pictures? If the fender washer hits the rod end, like mine did, you can cup the fender washer. Put a bolt in it, find a socket that matches the OD of the washer, and press the bolt so it pushes the assembly into the washer. Afterwards the washer is cup shaped. Gives clearance on the rod ends, but will retain the rod end if it fails.

Edit:


From this thread:
http://www.sonexbuilders.net/viewtopic.php?f=3&t=396

Page 5 this comes up. I discussed on my build thread too.

No, the fender washer was not hitting the rod end. It would without an extra washer to push the fender washer away from the rod end (which is what Sonex suggested too, but that further worsens the interference issue in other area). I have pics but I have never figured out how to post pics on this site.