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Vertical stabilizer rigging

J

JDA_BTR

Well Known Member
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I’m aligning and drilling the VS on my 8. It is even right/left to the HS tips and now it is time to align it to the centerline with the hinge brackets in line.

My question is about biasing to one side. The 7 has a little offset for the VS to account for yaw or torque or some such. Why does the 8 VS get setup on midline and no offset?
 
Because it was designed 5 years before the RV-7 was.
You could do it but then the empennage fairing will not fit.
Even with the offset, most RV-7s still have a rudder trim tab to fine tune the yaw trim so I don’t see it being worth the trouble.
 
I’m doing a fastback so I think the fairing will be a custom job anyway. I’ll stick to plans probably. always makes a new problem when I don’t. Curious if anyone did an offset on an 8 and how it worked out.
 
JDA_BTR said:
I’m doing a fastback so I think the fairing will be a custom job anyway. I’ll stick to plans probably. always makes a new problem when I don’t. Curious if anyone did an offset on an 8 and how it worked out.
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I offset the vertical on my -4 (don't remember exactly how much but it's documented somewhere) and still had to put a trim tab on.........and -4 is similar enough to a -8 to be something to consider. My trim tab would have had to be larger had I not offset it........IMHO YMMV...........
 
rvbuilder2002 said:
Because it was designed 5 years before the RV-7 was.
You could do it but then the empennage fairing will not fit.
Even with the offset, most RV-7s still have a rudder trim tab to fine tune the yaw trim so I don’t see it being worth the trouble.
Click to expand...
Scott - do you know off-hand if any of the factory motor mounts have offset built into them?
 
JDA_BTR said:
I’m aligning and drilling the VS on my 8. It is even right/left to the HS tips and now it is time to align it to the centerline with the hinge brackets in line.

My question is about biasing to one side. The 7 has a little offset for the VS to account for yaw or torque or some such. Why does the 8 VS get setup on midline and no offset?
Click to expand...
I recommend zero deviation from the instructions. An 8A and an 8 build an all is well (as in no trim tabs). I do suggest you verify that the HS measuring points are accurate (as in is the HS really perpendicular to the fuselage).

Carl
 
If you want to do it, you could buy the 7 VS forward plate. I can look it up if hou want. It's designed with the offset. About 1/4".
My enpennage fairing wasn't even close and it was designed for it. Fiberglass is easy
 
I followed the plan and after over 1 year for flying my RV8, everything was straight. Other than the obligatory right rudder pressure on take off, the airplane seems to fly straight. The airplane cruises at 8500ft with 75% power, the elevator is trimmed and it's in-trail to the horizontal stabilizer like when I did the alignment in my garage.
 
rvbuilder2002 said:
Every model designed to use a Lycoming has the engine thrust line offset towards the right.
I think the RV-12 does as well but I don’t remember for certain.
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Drawings 46 and 46a of the rv7 plans show the dynafocal ring offset to the Left, pilot side, about 3/4 inch.
 
Eric12 said:
Drawings 46 and 46a of the rv7 plans show the dynafocal ring offset to the Left, pilot side, about 3/4 inch.
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That is what offsets the thrust line towards the right.

If the prop and spinner are centered on the front of the airplane, and the aft end of the engine is moved left, the thrust line (crankshaft) will be pointed towards the right.
 
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