Side Hinged Rudders - Any Known Issues?

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wsimpso1

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My plan has been to hinge my rudder from the right edge of the fuselage and rudder and actuate it with a pushrod out near the left surface of the rudder. This sort of arrangement is used in some of the Glasairs.

Being as it is highly asymmetric, are there any known issues with such a gadget? Where issues arise, how are they fixed?

The only obvious one that comes to mind is drag forces on the rudder will tend to make it cock to the right, which would seem to require a trim tab to balance it.

Any feedback on this topic is welcomed. Any Glasair folks who can give details?

Billski
 

BBerson

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My Grob has the hinge on the right side and the pushrod on the left. About 5" thick at bottom, I think.
One issue is the rudder authority is poor in a right side crosswind. The Grob prop is left hand rotation so it yaws into the right crosswind with full takeoff power even with full left rudder. I think Grob should have put the hinge on the left side for more left authority in the right crosswind on takeoff. Left cross wind is never an issue. Of course, the left turning prop is opposite most planes. So yes, go right side for you.
One case of rudder flutter. A damper was required by Airworthiness Directive.
 

Vigilant1

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The Sonex aircraft also have this setup--the rudder hinge is a piano hinge on one skin of the rudder/V-stab.
I've never noticed anything untoward in flight, it works fine. Some folks find the look objectionable. Obviously, the control horns for the rudder cables are also different lengths so that the throw is equivalent (won't be a factor if using a pushrod). I'm not sure of the pros/cons for drag-- my guess would be it might slightly reduce drag as the piano hinge blocks bleed though air from the other side.
 
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BoKu

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The Grob sailplanes have side-hinged rudders as well. The one thing I've experienced with the G103 is that the rudder can settle hard over when you're slipping it one way, but not the other (and I don't remember which way). It's not like it locks in there, just that it takes centering pressure to bring it off the stop. Other than that, you can't tell.

All in all, I wouldn't be concerned about a side-hinged rudder, it's probably a reasonable design choice.
 

BJC

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Glasair rudders are mass balanced. They are hinged on the right side, as you said. Glasairs have been flown well beyond the published Vne and Vd with no problems. Neither of the two Glasairs that I have flown (one to Vne multiple times doing aerobatics) exhibited any unusual rudder behavior.


BJC
 

BJC

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The Grob sailplanes have side-hinged rudders as well. The one thing I've experienced with the G103 is that the rudder can settle hard over when you're slipping it one way, but not the other (and I don't remember which way). It's not like it locks in there, just that it takes centering pressure to bring it off the stop. Other than that, you can't tell.

All in all, I wouldn't be concerned about a side-hinged rudder, it's probably a reasonable design choice.
Sounds like rudder lock. AFAIK, that is not influenced by the side hinge arrangement.


BJC
 

JimCrawford

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As per BoKu's post above, many gliders have side hinged rudders. It is a simple solution mechanically and allows easy gap sealing with tape along the hinge line. The final drive to the rudder is a push rod to the opposite side.
I've never noticed any asymmetry of flight characteristics and rudder 'lock over' in full sideslips is common, probably the result of an unbalanced rudder - aerodynamically not mass.

Jim
 

Apsco17

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I'm building a BD-4C kit and it has the rudder hinged on the right side only. Same design for over 50 years, so it works. The BD-4C plans call for curving the left side rudder leading edge skin at the front of the rudder to the right so at full deflection, the lip on the left skin is still behind the vertical stab spar and doesn't catch in the slipstream. The left skin is about 0.75" longer than the right skin to provide enough metal to get the bend put in. I can get you more details if you're interested in doing something similar.

ToddDSCN0305.JPG
 

wsimpso1

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I'm building a BD-4C kit and it has the rudder hinged on the right side only. Same design for over 50 years, so it works. The BD-4C plans call for curving the left side rudder leading edge skin at the front of the rudder to the right so at full deflection, the lip on the left skin is still behind the vertical stab spar and doesn't catch in the slipstream. The left skin is about 0.75" longer than the right skin to provide enough metal to get the bend put in. I can get you more details if you're interested in doing something similar.

ToddView attachment 101269
Todd,

Thanks, the fact that it works fine is quite enough. No details needed. My rudder will be fiberglass over hotwired foam, but looking very similar to yours, including fairing in the side opposite the hinge line.

Billski
 

wsimpso1

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Many ailerons are hinged from one side of the airfoil and not in the center and they work just fine ;)
Yeah, but the left and right aileron are connected in opposition to each other. You end up with control forces that are the difference between their lifting forces. In a rudder, you get the whole thing...
 

Apsco17

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Billski,

Glad I could help you with your planning. I'm looking forward to seeing the pictures when you get the plane finished and flying.

Todd
 

Victor Bravo

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I'm sure there are very minor differences, or microscopic asymmetries in actuation force, rudder authority, etc. etc.

On a precision acro airplane with an airshow/contest pilot aboard, those asymmetries may be noticeable. Count Aresti and Sean Tucker and maybe the ghost of Bob Hoover might not like it.

On a point to point cruiser, or on a general purpose sport airplane, I can't imagine any of that adding up to much.

The structural, parts count, load path, and material usage benefits would probably put a lot more weight on the side of the scale favoring the side hinge. It (probably) also allows you to use the fuselage main side skin as the lower hinge mount, giving you an alternate or secondary load path besides the fin skin.
 

BBerson

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The side hinge is normally sealed with tape, which is difficult with central hinge. So could be more efficient.
I use white electrical tape and replace each season.
 

malte

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On my Lake, the Rudder also is hinged on the left side. I can make more detailed pictures tomorrow, if you like.

Flying the Lake, there is no effect that I would attribute to the hinge position.
 
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