Lil Sep (oz10934)
About this Plan
Lil Sep. Single channel radio control sport model, for Cox .020 power.
Quote: "Texans grow 'em small, too! Remarkably rugged little rudder-only radio control flyer is descended from long line of winning 'Separator' planes. Lil Sep, by Jim Houston.
During the entire time you are building this model keep one thought in mind at all times - it must be light! Do not use excessive amounts of cement and select your wood carefully. Use hard but light wood.
Let's start with the wings. Pick some fairly soft 1/16 sheet and cut 22 ribs. Cut the notches for the spruce spars noting that the upper spar is slightly ahead of the lower one so the upper sheet will fit flush with the back side of the top spar. Although the plans call for 1/8 sq spruce spars, 3/32 sq would be even better if your hobby dealer stocks this size. Cut the leading and trailing edge sheets from hard 1/32 stock and proceed with the wing construction as follows: Pin the hard 1/8 x 3/16 leading edge down onto a flat board that takes pins easily. Apply glue along the edge of one of the leading edge sheets and glue it to the back of the leading edge and also pin it to the board. Pin the trailing sheet in place. Glue the lower spar to the back edge of the leading edge sheet and place two or three ribs in place to locate it correctly and then pin it in place.
Glue and pin all ribs in place. Add the top spar. Run a bead of glue along the front edge of the top leading edge sheet and along the top of the ribs and the spar. Pin the sheet to the ribs and flush behind the leading edge. The ideal pin for this job is about 1/2 in long and very thin. Variety stores usually stock this item. Now glue the top trailing edge sheet in place making certain that a firm joint is made at the trailing edge. Add the top capstrips but do not capstrip the three center ribs as the center sec-tion will be sheet covered after the wing halves are joined together.
It is best to allow the cement to dry overnight before removing the wing from the building board in order to install the bottom capstrips. The plywood dihedral brace should be cut to the angle shown and be long enough to fit flush to the third rib of each wing half. In order to install this brace, it will be necessary to cut the center and second ribs behind the spars and remove the thickness of the brace- from the ribs.
Glue the brace to the two spars and then replace the ribs. Add the wing tips shaped as per plan. Cover the wing with light weight Silkspan or silk and try to finish it with no more than four coats of dope. The construction of the stabilizer may at first seem difficult but it is really very simple. This method results in a light but very strong surface.
Cut the 11 ribs and the two leading edge sheets and the two trailing edge sheets as shown. Bevel the edge of mating sheets and glue them together to form a 'V'. Apply glue to the ribs and insert them into the V leading edge. Space them correctly and line them up carefully by pressing the trailing edges of the ribs to a flat surface..."
Lil Sep, American Modeler, May/June 1964.
Direct submission to Outerzone.
Supplementary file notes
Article pages, thanks to RFJ.
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User commentsI had one of these, built about the same time as the magazine came out. I used a Babcock escapement and a Cox 020, with added up elevator from the Babcock. While it flew well, and even placed in a Class 2 contest, the only reason I placed was because I was number 3 of 3 entrants. It would be better as a tail dragger because it always hit the nose wheel first and bounced down the field. Now that I have the plans, an electric version may be in the works.
dougsmith - 28/02/2019
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