What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Horizontal Stabiliser - Zero Incidence

n4322b

Active Member
Following the build manual and using a 3/16 spacer under the rear spar of the horizontal stabiliser doesn't appear to produce the right result.
However with a 5/16 drlll the measurements seem to align i.e. the tooling holes are parallel to the longeron, F711 - the uprights, lie flat against the rear spar.
The low point in the skin is clear of the fuselage.
Has anyone else found the same ? Is it a typo in the manual ?

The front and rear spars are parallel - i.e. there is no twist that I can measure in the horizontal stab.
The fuselage was quickbuild and again I cant detect any misalignment.
I did ask the support guys but I'm guessing they are away on vacation.
Thanks
Ian
 
Do u mean the F-711E spacer under the rear spar of the HS ? Check your measurements. I made it per plans and mine fit perfectly. Not sure what result u are expecting. U did put the 2 F-798 shims under the front spar also ? Have 125 flying hours and she flies fine.
 
Spacers

Do u mean the F-711E spacer under the rear spar of the HS ? Check your measurements. I made it per plans and mine fit perfectly. Not sure what result u are expecting. U did put the 2 F-798 shims under the front spar also ? Have 125 flying hours and she flies fine.

Mine was per plan as well.
 
Mine too

Yeah, mine was per the plans and worked fine too.

I had a few of these moments during my build where I thought “surely I’m right and the plans are wrong”.. turned out to NEVER be the case LOL. Step back and go over everything you’ve done and study the plans, there will be something in there that will jump out at you and the light bulb will illuminate.

Obviously a change in incidence of the HS will have huge ramifications to the flight behaviour..
 
Do u mean the F-711E spacer under the rear spar of the HS ? Check your measurements. I made it per plans and mine fit perfectly. Not sure what result u are expecting. U did put the 2 F-798 shims under the front spar also ? Have 125 flying hours and she flies fine.

Thanks for your comments.

Yes the two shims are in and I began by using a 3/16 drill under the rear spar.

Measurements have been back and forward several times now.
 
Yeah, mine was per the plans and worked fine too.

I had a few of these moments during my build where I thought ?surely I?m right and the plans are wrong?.. turned out to NEVER be the case LOL. Step back and go over everything you?ve done and study the plans, there will be something in there that will jump out at you and the light bulb will illuminate.

Obviously a change in incidence of the HS will have huge ramifications to the flight behaviour..

Thanks for your comments. Yes I need to get this one right for sure.

I have't had too many of them - luckily. But a typo in the manual was a possibility that I think I can now rule out.
The measurements from longeron to tooling holes did not add up - several times, with 3/16 spacer.

An alternate route to checking zero incidence is my favourite - such as the relative positions of front and rear spars - awaiting Vans reply on that one.
 
Tooling holes

Thanks for your comments. Yes I need to get this one right for sure.

I have't had too many of them - luckily. But a typo in the manual was a possibility that I think I can now rule out.
The measurements from longeron to tooling holes did not add up - several times, with 3/16 spacer.

An alternate route to checking zero incidence is my favourite - such as the relative positions of front and rear spars - awaiting Vans reply on that one.

Double check the tooling holes are all in the correct position. I'm not sure if the are symmetrical with respect to the tooling holes. I they were installed opposite sides they might be fine in chord but tooling holes may be higher or lower. Just a thought.
 
Root Rib Tooling Holes

Thanks for your comments. Yes I need to get this one right for sure.

I have't had too many of them - luckily. But a typo in the manual was a possibility that I think I can now rule out.
The measurements from longeron to tooling holes did not add up - several times, with 3/16 spacer.

An alternate route to checking zero incidence is my favourite - such as the relative positions of front and rear spars - awaiting Vans reply on that one.

If it?s the tooling holes in the stabilizer root ribs that you are attempting to use for reference...well, I would not completely trust them. I recall that these particular ribs are sometimes misaligned where the flange is riveted to the fwd spar and this is evident by a slight distortion of the skin at the forward spar.

Skylor
RV-8
 
Thanks Skylor for that suggestion. I did check side to side for the tooling hole distance to the underside of the skin and in case that was as you suggested out of wad in some way. But nothing showed up all the check measurements were consistent.


I'll give it a day and go back through them again.

Thanks to all for the suggestions.

Ian
 
Back
Top