Click Here to return to the Index

Sailplane Construction Article Session #17

After I got back from lunching with my daughter in Flower Mound this afternoon, I sized and pinned wooden shims under the back of each rib to be cut off as shown below. Notice the rib cutting set up.


This is a close up showing how the vertical blade is placed up against the rib with a 3/8" balsa back up block to cut the rib guillotine style. I was careful to keep the blade vertical and up against the forward face of the rear spar to get a good clean vertical cut on the rib.
After the ribs and the wide trailing edge were cut, the elevator was separated from the stab primary structure as shown below. Notice the wide trailing edge cuts are on an angle because the elevator tip ribs are going to be inclined with false ribs rather than straight back.
This picture shows the elevator structure completely removed from the stab, which is now ready to have its rear spar installed.
The new rear spar was cut from a 1/4" medium hard balsa sheet slightly over size in height so as to be trimmed later. An aluminum angle was elevated on 1/4" blocks at each end and pushed up against the back of the 1/4" balsa rear spar to maintain straightness and to hold it in place up against the back of the stab ribs. Pressure was applied to back of the aluminum angle with wooden blocks pressing on the three steel squares. The pressure was maintained by clamping the wooden blocks with the three black Quick Clamps. This can be seen in the picture below. Then the butt end of each rib was CA'd to front face of the new 1/4" rear spar. 
This picture shows the new 1/4" rear spar from the front side. As you can see, by cutting the ribs off in front of the original rear spar, the butt end of the ribs make full contact down the new alternate rear spar.
This last picture shows the installation of the new 1/4" rear spar from the back side. This has truly been a tedious ordeal, but I think the results have turned out well. Tomorrow I will tie in the wide trailing edge with the new rear spar using 1/8" inclined false ribs on each end....................Tandy

Click Here to go to the next page (18)....