rudder alignment
 

Finishing a LT-40, what is the best way to make sure the rudder/elevator are aligned while applying glue? Clamps/pins etc

RE: rudder alignment
 

i use clamps on the horizontal and align it with my eyes and a triangle. I use epoxy to glue major sections like this in place. for the vertical stab after the horizontal stab is dry. I use 2 triangle placed on either side and run a piece of masking tape from hor stab tip over the top of the vertical stab to the other side and secure it to the other hor stab tip trapping the vertical stab (rudder) in place. double check with triangles to ensure the vertical stab is at 90 deg. I'll leave the triangles in place while the epoxy is curing so I can glance over to make sure I'm staying true.
follow the instructions for left and right alignment of the vertical and horizontal stabs.
It's not in the instructions, but after you have secured the verical stab in place glue a piece of triangle stock at the base of the vertical on either side for some reenforcement.
Your going to love the LT-40 I learned on one, have 1 stock, and 1 heavy modified.

RE: rudder alignment
 

Rudder and elevator are aligned? Umm... they are designed to move. You hinge them. Just push them on using the hinges supplied (if CA..) simply put a pin through the center of the hinge and push it in to the pin on one side, push the control surface on the hinges to the pin, remove the pin, make sure that there is as small a gap as possible while still giving full movement, then apply the appropriate glue.

Now, if you are asking about the horizontal and vertical stabs.. well, Jetmech has that answer for you.

Jetmech.. if I may add.. if you have cats around, watch that they don't just pop up in curiosity, and warp that alignment on ya. Yep..personal experience..ha..

RE: rudder alignment
 

Use a couple of popsicle sticks and 2 clamps to align them while you set up the pushrod and servos.

Ken

RE: rudder alignment
 

I believe he means the stab and vertical fin.

What I do is to start with the stab (Have the wing in place). Use 30-minute Epoxy. Put the stab on (without the epoxy) and check it visually with the wing to make sure it will line up. Sand the stab saddle if you need to.

Once it will line up with the wing, epoxy it in place, recheck the allignment (From top and rear) and once you're sure it's right, add a drop of medium CA in a few strategic places and hit them with accellerator to hold the stab in place while the epoxy cures.

After the epoxy is firmly set, use the same technique on the fin.

RE: rudder alignment
 

Yep, but I wasn't sure because there was sort of two questions in one there. I wasn't trying to be a smart*****.

For some reason, that always is what scares me and what I seem to procrastinate when building. The horizontal stab installation. The vertical seems to be easy enough.. I just use two triangle squares and clamp them together using spacers to square up the vertical stab with the horizontal stab.. but the horizontal stab has to be square with the fuse and the wings before I can do that and that's what really scares me.. because there seems to be no real set or good way to get those angled surfaces 'square' with anything other than using something to measure the distance from each wing tip to that side horizontal stab tip.

Is there some magic solution to that? I sure would like to know because my Seagull Super Star sits there about 80% finished except the horizontal and vertical stabs.

DS.

RE: rudder alignment
 

Ok, I'll go into a little more detail on the stab:

As I said earlier, mount the wing.

Now put the stab in place - measure both sides to make sure it is centered, and measure from wingtip to stab tip on both sides to be sure the stab is not cocked in the "Yaw" axis. (Note: if you don't have a long enough ruler to reach this, you can make due with a scrap stick. Even gluing a few scraps together will work, but DON'T use a piece of string. String can stretch and give you an inaccurate reading)

With the stab aligned, "Eyeball" from the back to make sure it is aligned horizontally with the wing. If not, sand the stab saddle and repeat the previous 3 measurements.

Once it all lines up, put it in place with 30-minute epoxy (You'll need the working time)

Repeat the 3 alignments steps again. (I never said this was going to be quick) You can use small slivers of scrap balsa to shim the stab horizontally if need be.

Once it is aligned to your satisfaction, you can do one of two things. Either walk away slowly and re-check it ever few minutes to be sure gravity didn't make anything settle, OR add a drop or two of Medium CA in certain areas and accelerate them to hold the stab in place. THEN walk away slowly and re-check every few minutes.

Don't just think that once it is aligned it will stay there! Keep checking for about 20 - 30 minutes until the epoxy has started to set.

I do not recommend using pins!! The force of pushing a pin through the wood is more than enough to knock things out of alignment.

After a while, the epoxy will be set enough that you can leave the room to have dinner, beat your wife, watch TV, or whatever else you had planned, but don't touch the plane for at least an hour or two so the epoxy really has a chance to set.

RE: rudder alignment
 

Good Tip!

RE: rudder alignment
 

Thanks, Mike. Well, no magic bullet for sure.. that's pretty much what I've been doing. But I did use a string on one and that seemed to give me mixed measurements... :eek: I do have a 48 inch 'yard stick' that is made of aluminum that would probably work just fine. But, as usual, those types of measuring instruments are not the same measurement on each side.. hard to describe, but perhaps a long stick would be better.. I would just have to mark the stick at the measurement points.

Dick.

RE: rudder alignment
 

[quote]ORIGINAL: MinnFlyer

Ok, I'll go into a little more detail on the stab:

As I said earlier, mount the wing.

Now put the stab in place - measure both sides to make sure it is centered, and measure from wingtip to stab tip on both sides to be sure the stab is not cocked in the "Yaw" axis. (Note: if you don't have a long enough ruler to reach this, you can make due with a scrap stick. Even gluing a few scraps together will work, but DON'T use a piece of string. String can stretch and give you an inaccurate reading)




I have used a dressmakers tape that is marked in both metric and inch. It seemed to work well.

RE: rudder alignment
 

That's a good idea, Jeff. Thanks for the suggestion.

RE: rudder alignment
 

Thanks for the tips- I'm actually converting the LT-40 into a taildragger with the new OS FSa .56. This alignment seems to be more important and slightly overlooked in the models I've built before.

RE: rudder alignment
 

CG,
I use a dress makers tape as well. It won't stretch like string will.

Ken

RE: rudder alignment
 

Thanks Ken. I will pick one up today.

Dick.