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Mat, perhaps the rudder floats a little around neutral, have a look at it. Std minor fix can rectify if that is the case. (sorry, shouldn't use the official word "minor" here)

 

 

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That makes sense actually, I'll look at it,

John McBride gave me the procedure and you will need to fabricate the aileron jigs to keep your reference points. You can do it with one but two is so much easier. Hope its the cure your looking for. My Phone number is on an eariler post and phone any time. Cheers Mike

 

 

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John McBride gave me the procedure and you will need to fabricate the aileron jigs to keep your reference points. You can do it with one but two is so much easier. Hope its the cure your looking for. My Phone number is on an eariler post and phone any time. Cheers Mike

where can I find the specs/measurements of the jigs, also if youve got a copy of the procedures it would be handy, I also have some pics of the aileron hangers I made if your keen, if you PM me an email I'll send you some pics,

cheers Matty

 

 

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Went up last night in pretty still air to have a wander, the rudder issue isn't really an osiliation but seems to be effected more by the fuel load being uneven than anything else I've been in, it does have one issue though that I'd like to try and fix, if you push in rudder either way it doesn't come back to where it was but finds a new place to rest, the hinges are all free and lubed ,I have heard of some aircraft not having a enough rudder area for it to trail in the same spot every time , I had thought of a trim tab but it would only be good for one amount of fuel it seems. I'll still check the rigging of the whole thing cause I think it needs something ,but just thought I'd post some thoughts.

 

 

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.... if you push in rudder either way it doesn't come back to where it was but finds a new place to rest ....

I think this is what djpacro was referring to above, and I think the 'minor' standard fix he was referring to is a double sided fixed anti-servo tab. You may have seen them on most of the Rutan style ships, a thickening of a part of the trailing edge of a control surface, with a sharp edged square (flat) rear face. It has the effect of generating a pair of 'burbles' (small contra-rotating vortexes) behind that part of the trailing edge. The drag of those vortexes pulls the control surface into a true trail position instead of it hunting around in the turbulent wake of the fixed surface ahead.

 

On craft like yours where the control surfaces aren't composite or timber the same effect can be achieved by fitting a pair of trim tabs opposing each other. You will have seen (or already have) the one sided sheet aly trim tab that you ground adjust by bending, to trim the rudder for cruise condition. The opposed pair is just the same but there are two of them forming an outward V shape. They still work as ground adjustable rudder trim by bending one more than the other. If you want to try it first before drilling and riveting you can stick them on with quality double sided mounting tape to check that it fixes the problem.

 

 

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Guest Maj Millard

Matt, I recently encountered a Lightwing fresh out of major rebuild that flew terrible. You needed left stick (lots) and half right rudder to even sort of fly straight. As you know an aircraft is not even close to being efficient in that mode. At altitude I just let go of everything and had a look out the window.........one aileron was flying 1" down and the other 1" up...OK.

 

I landed and we adjusted the ailerons to where they should have been (slightly reflexed up on the LW is good for an efficient cruise.). We then tightened the r rudder cable to centre the rudder and bingo.....next flight she almost flew straight hands and feet off. After the next landing we further dropped the right aileron about 1/8 th of an inch and now she is fine.

 

The Lightwings do have the foward rudder springs attached to the rudders, and yes other than keeping the rudder pedals upright, they also act as centring springs for the rudder itself. Sometimes just centering the stick and rudder pedals on the ground, (with tail supported if its a Taildragger) and then standing about 20 FT behind the aircraft just to visually see where things are sitting, can tell you a lot.

 

Your yaw 'hunting' problem sounds more like slight lack of fixed vertical fin area, and probity kicked off by the larger engine up front or prop slightly off thrust/ flight line to one side.....doesn't take much for cause and effect.............Maj....

 

 

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Thanks maj , and clouds , I've seen a similar trim tab on another aircraft( maybe a Foxbat) on the elevator , I thought it was a pretty crapping trim tab but maybe it's got a problem with the elevator hunting around a bit, thanks fellas

 

Matty

 

 

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  • 1 month later...

The springs on both the rudder and the ailerons are adjustable and apply a pre-load to both circuits, especially the rudder. I have found that the rudder springs lose their tension over time and may need replacing if they are at the end of the stops.

 

The other problem that occurs is the horn on the rudder becomes bent due to big feet putting pressure on the pedals so check that this is straight. I have seen one where one side was bent more than the other and the aircraft flew in a slight side slip all the time and will cause the fuel to drain one tank before the other.

 

 

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Thanks OME, I was thinking a remeasure might be in order , short hops around the valley don't always show up problems , I've just done about 43 hours in the last ten days and all the niggely things get pretty annoying after a few hours in the seat

Where did you go?

 

Kaz

 

 

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W

 

Coldstream, narromine, white cliffs, noccundra, windorah, longreach, orchid beach, port macquarie, taree,cold stream,

Where did you cross the Divide on the way to Port ? I'm a bit nervous about doing it up there.

 

Kaz

 

 

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W

Where did you cross the Divide on the way to Port ? I'm a bit nervous about doing it up there.

 

Kaz

Came down the coast to port mac , then took the vfr route behind willytown , and crossed over to Bathurst , had a howling headwind , was down to 37 knots GS at one point, not nice !

 

 

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