In November I showed you the fuselage construction. Last month I used this space to provide the final installment of the "Rebuilding the 30% Extra" series. The Extra was a very good series, and the airplane is superb!  I really do like the Fox 3.2 cu. in. (50+cc) gasolene engine.  It starts very easily when I remember to turn on the Radio, has 26 pounds of thrust with a 23 x 8 propellor and has been nothing less than perfect in terms of dependability and ease of operation.  And the convenience is terrific!  No glow igniter, fuel cost is a little over $3.00 per gallon including oil mix, and very little, if any, mess on the airplane.  As of this date I have logged six flights on it and a couple of others have flown it as well.  Josh Price flew it at our "impromptu Jumbo" last month and showed that it is plenty capable of 3-D flight.  I'm looking forward to Spring!

In this article, and the next, I will concentrate on the wing!

First thing is to cut out all of the ribs.  Since the trailing edge is swept, every rib on each wing is different and must be cut separately.  However, since the "outside" wing (right wing, since I fly control-line in a counterclockwise direction) is identical to the "inside" wing, except that it is 1 inch shorter in span, we can stack two "blanks" and cut both the inside wing ribs and outside wing ribs in pairs.

I am using one-eighth of an inch (1/8") thick balsa for the ribs, and all ribs will be the same thickness. As you can see, I have cut "blanks" out of 1/8" balsa sheet and adhered the full-size rib pattern to a pair of "blanks". There will be only one center rib (R-1) and it's special since the 1/8" plywood bellcrank mount will be mounted through it. Also take note that Rib R-1 and both of the R-2 Ribs have been reduced in size by 1/16" on both the top and bottom of the ribs to allow for the balsa center sheeting between the R-2 ribs.

In the left photo I am beginning the task of cutting out the ribs on the bandsaw. I generally use a blade that is 1/2" wide because it makes a much straighter cut than a smaller blade. Of course, I can't cut as small a radius with it, so I usually will cut well outside the "finished line", then come back and trim up to 1/16" of the line.

You can see that I have already "trimmed" the bottom of the rib to within 1/16" of the "finished line" and am just starting the cut on the top side of the rib. With a good bandsaw this is very quick work. Each pair of ribs only take about one to two minutes for this "rough" cut.

The photo on the right is a closer view of the rib being cut. There are a few things to note:

1. The spar notches have been "rough" cut, still standing proud of the line. These will be sanded to the exact fit later.
2. The "slot" for the plywood bellcrank mounting plate will be cut just before gluing the rib in place to prevent premature breakage.
3. The holes, shown in the top photo, will be drilled after all ribs are cut and spar slots aligned. Also, it is not necessary to drill the holes in the "outboard" wing since no flying wires will be passing through it. The small added weight is not of concern since we will be adding about 1 ounce of weight to the outboard wingtip to counter the flying wires anyway.

After sawing each "pair" of ribs on the bandsaw, it is necessary to sand the ribs to the exact shape and size. In the lower two photos, I am using a disc sander to bring the rib right to the "finished line".

At this point, its just doing it all over again for each set of ribs, then sanding the leading and trailing edges of each pair to the "finished line", and hand sanding the spar slots.