Tail mounting Q's

[flydjd]

Hi all and Happy Easter,

I have searched the archives to no avail and would like some help please !

Status :- HS mounted with all bolts installed, VS same and Rudder hung but this has some issues. Rudder stops not yet made/fitted.

1. I followed the instruction sequence and drilled the VS to the F-781 attach plate to the HS and have the correct 1/4" offset with the 3 brackets lined up with a straight edge. When I then added the extra washer on the left side between the VS and F-712D up elevator stop the 3 hinge brackets no longer lined up ! To get the brackets back in line I have added washers between the 2 lower left bolts at the base of the VS.
This results in the rudder swing being slightly less to starboard.

Has anyone else been through this scenario and have some people left out the extra washer ? (Or added the others ?)

2. With the rudder in place and the Rod End Bearings set as per the Dwg dimensions my horizontal gap between the rudder counterbalance arm and top of the VS is only 5/32" at the rear and 4/32" at the front. To even this out it requires several turns of the top R.E.B. out and equal number of turns in of the bottom R.E.B.
Now however to achieve the 35? rudder swing the rudder bottom fairing is pushing against the botom fuselage skins.......catch 22

Again has anyone else experienced this interference and also what size horizontal gap between the rudder counterbalance arm and rudder do I need?

I shall check back later as now is Family time on bicycles as it is 21?C here .... we are off to the Biergarten !!!!!!

 

[dhall_polo]

my case

- I just followed the directions as-is. only added the 1 washer, didn't add any at the bottom. I didn't experience any noteworthy alignment change.

- I filed/trimmed away a little of the flange on the lower right end of the fuse to resolve some rudder fairing interference.

 

[flydjd]

Others experience ?

Thanks for the reply Don,

can anyone else share their experiences please......

 

[flydjd]

Update to #2

As my build is a QB I went back to the plans and found Dwg 18 which gives the F-718 Longeron details and discovered that according to detail C the rear most flange/leg should be 19/32" - and mine are about double that. Which means that I can shave off 3/8" of the flange and tail skins to give adequate rudder swing clearance without contact of the lower rudder fairing.




With ref to my Q1 can anyone share their horizontal rudder counterbalance to VS clearance dimensions please ?


Thks

 

[tgmillso]

I can't for the life of me make a -10 washer work.

Regarding this spacer washer between the F-712D up elevator stop and the forward face of the vertical stabilizer rear spar, it really seems too thick with a standard AN960-10 washer. If moving the front of the vertical stabilizer 1/4" to the left at a distance of approximately 26" from the rear of stabilizer, then for a 3" arm (approximate) from the pivot point (the interface of the vertical stabilizer rear spar and the right longeron) to the left bolt hole on F-712D, then this spacer thickness should be 0.250x(3/26)=0.0288". I wedged a 0.032" shim in there just as a test and looked much better.
Thus I guess I should use a thin AN960-10L washer instead of the standard -10, or am I missing something here that is blindingly obvious?
Cheers,
Tom.

 

[RV7A Flyer]

Regarding this spacer washer between the F-712D up elevator stop and the forward face of the vertical stabilizer rear spar, it really seems too thick with a standard AN960-10 washer. If moving the front of the vertical stabilizer 1/4" to the left at a distance of approximately 26" from the rear of stabilizer, then for a 3" arm (approximate) from the pivot point (the interface of the vertical stabilizer rear spar and the right longeron) to the left bolt hole on F-712D, then this spacer thickness should be 0.250x(3/26)=0.0288". I wedged a 0.032" shim in there just as a test and looked much better.
Thus I guess I should use a thin AN960-10L washer instead of the standard -10, or am I missing something here that is blindingly obvious?
Cheers,
Tom.

How much offset from the centerline do you get at the front of the VS with the regular washer?

 

[tgmillso]

About twice what I should. I ended up using some .025 sheet as a shim and it came out fine. I've only just this moment drilled everything in place. It came as close as perfect as I could get it, with the hinge line dead on, tip measurements within 1/16" of one another. There is a half inch forward tilt in the entire assembly, however I couldn't seem to rectify this and still keep the hinge line dead straight, which was a bigger priority. I suspect now with the specified -10 washer on the left side AND a -10L on yet right side, this would set the alignment at the required 1/4" left and kick the rudder back 5/32", which would take it back closer to where it should be. For me it's a little late, as I've already drilled the F-781, and they don't grow on trees around here, so I guess using the second spacer will have to wait until the next build.
Tom.

 

[RV7A Flyer]

I'm sure it'll all work out fine in the end. I just find it odd that the regular washer didn't do the trick...might be a little bit of twist or something that may not be visible (or easily measurable).

Worst that can happen is you could end up having needed that extra bit of offset, in which case...a little trim tab time

Build on!

 

[tgmillso]

I'm really convinced that this second washer on the right side would have solved the problem. I confirmed that the leading edge of the VS at the point near where it intersects with the turtle deck is 1/4" lower than it should be (according to the plans it is slightly lower than the deck). Using this additional washer would also mean that I would have had to add an 0.032" spacer between the forward spar and the F-781 bracket, as my setup was flush against the F-781. I guess the most important thing is that the hinge line was straight, which it is, I only hope that this slightly lower nose position doesn't cause secondary issues when I fit the fairing. Time will tell.
Tom.

 

[Raymo]

I seem to recall (~2 yrs ago) leaving out the shim washer as everything fit perfectly without it.