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Mounting the H-S

briand

briand

Well Known Member
In the instructions on page 8-17 (rev. date of 5/28/04) second para. under "Mounting The Emp.", it tells you to verify the h-s incidence angle by placing a 1/16" spacer on the top-center of the rear spar. Now, I can't find anywhere that tells me what it should be. Level? 0.5 degrees, like the wings?Or something else? It says use a level which wouldn't give you anything other than level or not level. I used a smart level and got 0.5 degrees with the 1/16" spacer.
 
Spacers and Level

Brian,

Here's what you want to do - check Drawing 41 and builders manual 8-17

First - level your fuselage - for 0 degrees lonitudinally. (Actually this isn't necessary as long as you make your fuselage level measurement and your HS level measurement the same)

Use a 1/4" spacer on the TOP of the forward HS spar and a 5/16" spacer on the TOP of the aft HS spar. (this is the same as your 1/16" spacer on the aft spar, but it gives you better surfaces to get more precise measurement)

I used simple old 1/4" and 5/16" drill bits for the spar measuring spacers and taped them onto the spars.

Don't forget the F810E spacers (1/8") that go under the forward HS spar and a TEMPORARY 3/16" spacer under the aft HS spar. the F810E spacers will ultimately become part of the forward HS spar attach structure and the 3/16" spacer is to simply raise the aft spar to get it about where it needs to be.

With the fuselage leveled both laterally and longintudinally and your level on teh spacers, then you are adjusting your HS so that the level reads LEVEL. If you have a Smart Level, that is an even better way to go, but hey, level is level and an old bubble level will work just fine.

The manual confirms in 8-17 that you are looking for zero incidence from the centerline of the HS relative to the fuselage longeron. The HS centerline is near impossible to measure using the structures, so that is the reason for the spacers on top of the spars of the HS. This sort of gives you an extended, but parallel point of measurement for the HS centerline (in sideview) so that you can measure relative to the fuselage longeron. both readings should be the same = 0.0

Don't forget to square the HS with your fuselage by using a common centerline point on the fuse and common measuring points on each side of the HS.

Hope this helps.
 
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Good thing I asked before proceeding. I was completely confused. I had thought that you threw out the 1/4" spacer on TOP of the front spar and 1/8 of the 5/16 on TOP of the rear spar (shown on DWG. 41) because you already had 1/8 under the front. When actually they are just giving you the 3/16" for an estimate UNDER the rear spar. See what I mean. I set the h-s back on the fuse, checked everything out, clamped it and now it looks good. Now its time to move on to the V-S. :eek: Thanks
 
Glad everything worked out. If I recall correctly I didn't have to make any adjustments either - that 3/16" spacer on the rear spar gave me exactly 0.0 degrees of incidence relative to the fuse longeron.

Have fun drilling the foward attach holes! Suggest either a long 8" bit or a good angle drill for some of the holes.
 
I got them drilled. I went a little further aft than the 15/32" called out on the dwg to get more edge distance on the 1"x1" 810C. If I ever build again I would use a1"x1-1/4" angle for this part.

Do you remember what distance you put between the top of the tailwheel mnt. and the bottom of the V-S spar? I have been marking the V-S spar up for pilot holes but would like to get the bottom most hole lined up with the tooling holes in the F-812's. I was thinking about 1/8"-3/16" but not sure.
 
briand said:
Do you remember what distance you put between the top of the tailwheel mnt. and the bottom of the V-S spar? I have been marking the V-S spar up for pilot holes but would like to get the bottom most hole lined up with the tooling holes in the F-812's. I was thinking about 1/8"-3/16" but not sure.
Click to expand...

If you're hunting for the right vertical place to put the vertical tail, this is a common question from just about everyone that has done it on the -8 (myself included). There is actually a measurement on one of the drawings (sorry, don't have them here...) that gives the exact dimension. It's not, however, in an obvious place on an obvious drawing - check every drawing that shows the vertical tail and the aft end of the fuse, and you'll find it!

Paul
 
Brian,

Paul is right on the money - the plans do have that dimension, but it is buried somewhere. I remember having to "go fish" for that dimension too. Not sure why they didn't make such a key measurement obvious.
 
Drawing 27!!

Take a look in zone G-2 - gives the dimension from the lower rudder hinge to the bolts that go through F-812B.

Paul
 
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