Because this Blog is updated regularly it is a good idea to visit at least once a week so as not to miss anything. If however you are not a regular visitor, please use the archive links, at the bottom of the side bar on the right, to view postings that have moved off the main page. Or type a key word in the search block in the black bar at the top left and click on "SEARCH BLOG" and it will take you to the posting within our Blog. (For instance, type "Jart" and all the post that mention Jart will open) The Label at the bottom of a post can also be used. Click to get all posts with the same label together!
This BLOG is best viewed at a screen resolution of 1024x768. Click here to get instructions on how to adjust your monitor to these settings.

Tuesday, November 13, 2007

A technique to rig your V tail up without tears.

Simple cardboard Jigs that can be used to help the rigging of your V tail.(Photo 5)

Photo 1
Photo 2

A year or so ago I attended a building group (Makulu) at LST in Pretoria.
This was my first experience with building a complete composite glider.

All the main parts (wings, wing joiners, v tails, fuse) were done in moulds.
After that it was up to the individual to complete the assembly and install the R/C equipment.

I took me some time to get the itch to complete it, but eventually my good friend Evan got me going (and helped) to finish and fly it.

One of the things that turned out a little more difficult was to align and fit the V tail.
The way that Evan and myself did it was by the “aim and drill method”. This was okay, but the angel of the V between the two tails turned out to be to flat, or more than the normal 110 deg.

So a little while ago I decide to rebuild and fit a completely new V tail with the primary object to reduce as much weight in the tail as possible and at the same time correct the angel to be with in 110 deg.

This time I did the job alone and with some of Evans' and my own ideas, I set out re rigging the V – tail. I hope that the pictures will help with the explanation of this method.

The biggest problem of fitting the V-tail is that involves multiple angles

1) The angel between the two tails must be between 105 and 110 deg.
2) The V must align with the wing so that the V does not lean one way or the other off vertical.
3) The incidence to the wing must be the same for both tail’s to the main wing.
ie. Zero degrees.
4) Cord wise the carbon joiner must be square to the tail saddle and preferably no gaps between the V tail halves and the fuse when in position.

To solve (1) and (2) I used a template (See Photo no1 and 2) with correct angels marked out on it, form vertical or imaginary perpendicular line that will be use to line the V up with the wing assembled on the fuse. This card is carefully cut out and temporarily stuck to the tail saddle. Each V tail half should align to the edge of this card for proper alignment. If you know that your joiner pipes are parallel to your tail surface you can then align your carbon joiners to the edges of this template.

To solve (3) above you might want to use a laser incidence meter, but in my case I did not need to go to this extend as the outline of the saddle was already molded and I used the cord line from the L.E. to the trailing edge to locate the center (top /bottom).
Now I transpose the distance from the L.E to center of the carbon joiner to tail saddle. This is the point that you now have drill to the thickness of your tail plane joiner.

Photo 3

Photo 4

To aid the correct angle to drill at in both planes I used a Fisher plastic wall plug as a guide (see photo 3 & 4 and cut it more or less in half so that a 4 mm drill could just fit snugly. I use a drop of supper glue to hold this (centered and) in position and make sure that the join was dry and firm before I started drilling the 4 mm pilot hole. This hole goes right through the fuse (as to anchor the joiner on the other side of the fuse). Now using a 4mm piano wire make sure that your pilot hole is aligned with the card looking form the back and that it is square from the top.(see photo 5). If you are happy that the pilot hole is aligned okay, repeat with a 5 mm drill and the finale drill size of your joiner making any angular adjustments if necessary.
After the final drilling your joiner should fit snugly and should be correctly aligned.
At this stage you can remove your temporary guide (fisher plug and clean any excess super glue on the saddle surface.)
Now you can test fit your V-tails and once happy, can use your favorite epoxy glue to secure the carbon joiners in position. When dry proceed to fit the 2mm piano indecent pins to the back of the V-tails and when dry fit them on and mark the point on the saddle center line and drill the corresponding hole in fuse. You can now also remove the card with the V-angle on and clean any excess supper glue of. I keep my V-tails on by means of electrical insulation tape but any other way of holding the V-tails from sliding out can be used.

No comments: