rglawhead

My Feedback: (34)

Does anyone have any hints about checking the alignment of the horizontal stabilizer prior to final glueing? I measure from the wing tips to the tips of stabilizer to ensure this distance is equal on both sides of the fuselage. This centers the stab on the rear of the fuselage. I then try to compare an imaginary line going through the length wing with one going through the length of the stabilizer to make sure they are parallel when viewed form the front. This latter process is so subjective, that when reevaluated at a later time, I wonder what the *&%$^& I was thinking, and the tip of the stabilizer either droops or is elevated compared to the wing tips. The imaginary lines, which initially appeared to be parallel, are really not. Is there a tool ,or some technique, which would remove the subjectivity of this process?

Ed_Moorman

My Feedback: (1)

When you are checking for parallel, you must stand back several feet. I like about 15 feet to get a good perspective. I find it I just hold it at arm's length, I can't get a good alignment.

Next, once you have backed off, move your head up or down until you see a gap betwen the stab and wing. Then move the other way until one side or the other appears to touch the wing. if one side touches first, the stab isn't parallel.

I also like to use 30-minute epoxy. I line it up to start with and level the gluing area. Then I remove the stab and coat it with glue and re-install. Now I go back and re-check the alignment. The slower curing epoxy lets me make last second changes.

leftnut

My Feedback: (1)

if you eye ball it , you'll get fool espacially wings with diehedrals.
close at least one eye.

makesure the wing tip have equal distance from the surface you are working on.
you can use styrafoam cups , ad spacers accrodingly.

gluing the tail section
i use a triangle to makesure the tail feather have a 90 with the fuselage.
i use a trianble that i've cut off the coner at the 90 deg if there's flairing
between the verticle stab and horizontal stab

to get the main wing or tail feather to center...i use the tape /string/ pin
method.

for the tail...
i use the triangle to draw a line useing the TE of the tail as a guide at the half
piont .
pin the string to the center of the fuselage at the main wing's TL former.

adjust the for centering accordingly to have equal distance wing tips.
the tape wrap around the string is use a marker .

once the tail section has cured. and i'm happy with the 90/90/90
fuse/horizontal/ verticle, and centering of the horizontal.

i mount the fuselage to wing and trial fit.
the tail wing's tip should also have equal distance from the working surface, if
the main wing tips have equal distance.
i sand the fuselage wing's saddle accrodly to get the tail feathers to align with
main wing or to get the tail's tip to have equal distance from the bench.

you can also use rubber foam tape as shim if you have an ARF.

MinnFlyer

My Feedback: (4)

You're starting out right...

1 Make sure the stab is centered
2 use a tape measure to check the distance from the wing tip to the stab tip
3 Eyeball the stab against the wing (as the others have said) Close one eye and align your eye with the center of the fuse. Slowly raise or lower your eye to get the top of the stab to line up with the bottom of the wing (or vice versa).

If the stab "Meets one side of the wing while there's still a gap on the other side, the stab is tilted. Move it so that it aligns with the wing, and using slivers of balsa, shim it in place. Add a drop or two of Medium CA to a few critical areas (with accellerator) to hold everything in place while the epoxy cures.

Once the epoxy has sat at least a few hours (I'm talking 30 minute epoxy, don't use anything shorter for this) You can fill any gaps that may have formed from the shims.

spokman

My Feedback: (2)

After measuring use the ole Mark 1 Eyeball. Accurate to millions of a degree, never fails. Unless excessive alchohol has been consumed.

MSP1957

My Feedback: (1)

boy, what a timely thread! Came accross this last night at work. I am building a EF Yak54 arf. My other planes were always a struggle to get the horizontal stab right. I really di not want to mess up this Yak (beautiful plane javascript:void(AddText('')). Have the day off today and too windy to fly so I spent at least a hour fine tuning the horizontal stab using all your methods untill it looked about perfect. i will epoxy it later this evening. Thanks for the great info!

Michael

Crashem

If your wing is rubber banded on I'd measure from the tip of the horizontal stab to a point at the tip of the fuse that way provided both sides of the fuse are equal in length you don't have to worry about making sure the wing is square and centered with respect to the fuse.

Gordon Mc

My Feedback: (11)

Yup ... and don't use the spinner etc as your refernce, since the engine may have a non-zero thrustline.

The way I do this part of the alignment check, is I stick a pin into the centerline of the fuselage, near the nose of the aircraft. Then I attach a (non-stretch) string/thread/etc to the pin, and then I pull the string out to the reference point on one stab tip and "mark" that point on the line by holding my thumb-nail on it - then swing the string out to the other side and compare it; make a slight adjustment to the stab to "split" the difference, then repeat.

Gordon

MSP1957

My Feedback: (1)

No rubber band. Two piece wing with CF rod and bolts for attachment. Just finished, went quite well. I will have to touch up with more epoxy inside since there are many non-contact points showing thru. Not too much though, to keep weight down, but do not want a failure in the air.

Michael