Hi all,
This is my least favourite operation building a kit plane or ARF. Although I've done it several times, there must be an easy way to get it right.

Getting it parallel to the wings is not that hard- eyeballing it seems good enough. But getting the distance from tailplane tip to wing tip equal on both sides always seems to give me heartache and has me spinning in circles trying to measure the distances with an ungainly long ruler or tearing my hair out as to where exactly the "tip" is on slightly rounded edge.

There must be a tried and true method out there - what, for example, is the "pull a string" method ? And any other methods that work I'd love to hear about.

Thanks
Wayne from OZ.

I use the pin and string but I use monofiliment fishing line as many "strings" will stretch.

No..No..don't eye ball for stuff like that..it's an illusion as you might know.
You should always only use one eye when eye balling

On top of that... we all have blind spots in our eyes. Our brain generate false images to cover
those spots.

Yeap use pin and string...yeap strings will stretch. i also use a little piece of tape as a marker for the string.
Then I use a marker or a pen to trace lines ..on the bottom side of course.
Measure to the stab's trailing edge...

On top of that you must also makesure it's horizontally aligned
So...i use a triangle or something with 90 degree coner. I butt it to the side
of the fuselage on the bottom side of the stab.

Some people use cups and have the horizontal stab sits on the cups until the glue dries...true. ture If your
table or building surface is perfectly flat.

which is why I build on glass

For the vertical stab, I also use a triangle with a cutted or drimel.. out coner

I'm a nitro flier...so i always use epoxy for stuff like that.

I just started putting T-Pins three on each side to hold the elev. in place while you measure, it works great just put the T-Pins right beside fuse and into elev. get it close by eye put the pins in and if you need to move it pull the pins from that side and slide it or whatever way you need then put pins right back and it wll hold it in place. Pull it out and put your epoxy if using that and then slide it back in put your pins back in the holes you made and very little adjusting is needed. If not epoxy you can turn it on itside and put your CA without it slipping while you glue it. I have a straight edge I use and mark on both sides when i get it set and then you just use it on both sides when doing your final epoxing or ca. However you measure the pins hold it in place great.

Rather than string or monofilament (which has a lot of stretch), I use heavy duty cotton thread used for sewing on buttons. It has almost no stretch. A piece of masking tape folded over will slide easily so you can quickly compare each side. Hardest part is getting the t-pin located exactly on the centerline.

Brad

I use a very lite aluminum 48 in ruler and pin or clamp the stab in place , once it`s where it needs to be , then mark it.

For the horizontal on the stab , I put my cheap laser line marker on a camera tripod and throw a beam , level across the the wing edge and the edge of the stab .

I use the string method myself. If you check around you can find kevlar thread at the fly fishing shops - absolutely no stretch. I tie it to a T-pin at the nose of my bird. I then use my favorite sharpie to mark the string at the tip of the rudder.

I use Dacron fishing line, and put a straight pin in the front center of the fuse to align the stab. once you get the stab centered by measuring equal amounts from fuse to stab leading edge tip mark those points with a pencil/stickpin/sharpi.its pretty simple after that. if you have to mark a wing for mounting bolts do just the opposite measure from the rear fuse center to each trailing wingtip after the wing is centered. when you do this if the fuse is odd shaped or is a biplane you can reference the wings for the stab alignment. leveling the horz stab. I level my building surface and set the horz stab on cans, then shim the fuse up to the stab. the vertical stab is pretty easy after that just use a triangle like was said here.

I think that all the line methods have problems with stretch. What I use is a couple lengths of music wire (.032 - .039 - .047) jointed together with a small wheel collar. One end has a right angle bend on the end to drop into a hole drilled into the firewall or block added for the measurement. The other end I put a piece of masking tape which I mark so I can compare left side to right.

simplest is to use a cloth measuring tape.Seamstress supliers, Du-bro or maybe Great Planes sell these. They have a small d-ring on the end to hook over the pin, with the measurment right on it. Simple to measure to each wing tip or stab tips.

Thanks for all the replies, my computer went down shortly after posting so I've only just got back to read the results. Lot's of good tips.

Cheers,
Wayne from OZ.

Another thing is to check often when you glue up with epoxy. If it's 30 minute epoxy, check your measurements every five minutes or so. I've braced things to set up only to come back five minutes later and have things drift a bit off and needing adjustment. Keeping a close eye on your tail feathers to assure they set up correctly is well worth the time.

somegeek

Go to a fabric store (you know.. where you can buy material for sewing). Get yourself two good cloth measuring tapes. It is stiff enough to use, you can pin one in place on each wing tip at the same point on each side and with the pin through the tape at the same point on each tape. Then pull it over to the tips of the hor stab. Because both are the same, the measurements will be easy to make on each side.

Pin the hor stab in place and mark it with a sharpie marker (permanant but will wipe clean with alcohol after you are done).

Strip off the covering, then epoxy it in place using 20 minute epoxy. After you apply the epoxy, and before it sets up, re-measure it and check that it is level (parallel) with the wings. The laser measurement that Moondoggie said is the best way. Then, tape it secure and make sure it does not move while the epoxy sets up.. don't move it for at least an hour.

CGr.

Rather than string or mono,try dental floss. I have used it for stitching the back side of fish mounts because it would'nt stretch even when wet.
fredsedno

I suppose that would work better than ordinary string. But the taylor's tape works great because it has measurements on it that can be directly related to distances between wing-tip to hor/stab tips. And it won't stretch either. Cost: for a real good one, maybe 5 dollars. For a cheap one, maybe a dollar or so? I splurged and bought an expensive one. Paid $4.95 for it.

CGr.

An old collapsable antenna works VERY well.

Ya know.. that's a great thought! Certainly easy to make that work.

I'd like to second that one! don't get any easier than that method.

Antenna is a great tip. Thanks for the tip... I have also measured then remeasured then glued and remeasured then masking taped then measured and remeasured then I measured again. The antenna will help with all this measuring. I guess I am really anal about getting it exactly perfect right down to 1/32 of an onch......but hey all my planes fly straight so its worth the time.


Jay