La Libellule (oz7494)

About this Plan

La Libellule. Unusual free flight biplane glider.

Direct submission to Outerzone.

Update 1/4/2026: Added translation of the article into English, thanks to Jean-Marie Piednoir.

Quote: "Libellule glider biplane. By Jacques Bluzat.

The fuselage will be built using the usual method, i.e., two sides (made of 2.5 x 2.5 mm hardwood) joined together, taking care however, because the cross-section of the original fuselage is not a rectangle but a trapezoid whose upper base (line C) is 5 mm shorter than the lower base (line A). Check the straightness of the assembly during construction, then add two 6 x 3 mm hardwood strips to each side of the fuselage, tapering them at each end along line B. The skid will be cut from 3 mm plywood with notches, then fitted into the lower cross members of the fuselage. False triangular formers made of 1.5 mm plywood will be added to each side of the skid, and the whole assembly will be planked with 1 mm plywood to prevent punctures and tears during landing. The skid will be followed by a false keel made of 6x3mm hardwood (diagonal spruce) tapered towards the rear. The nose will be carved from a hollowed-out block of fir or basswood, fitted and glued to the first 3mm plywood frame.

The pylon supporting the upper wing will be cut from 3mm plywood, notched at its base, and recessed into the upper fuselage cross members. On each side and at its base, false frames made of 2 mm hardwood will be placed to hold it in position and provide added strength. This pylon will be profiled with 5mm balsa sheathing placed on each side. Don't forget to glue the upper wing tongue (made of 4 mm plywood, curved by heat). Extending from the canopy, two 5x2 mm hardwood strips (held by supports) will form the upper edge of the fuselage. The lower wing tongue will be held in place by four 3x3 mm strips, all glued after checking the angle of attack (i = +2°). The tail tongue (made of 2.5 mm plywood) will also be held in place by a balsa sheeting made of 1.5 mm balsa. Its position (0°) should also be checked. The upper fin presents no difficulty; it is of classic construction: 1.5 mm ribs threaded onto a 5x2 spar, a 5 mm balsa leading edge with profiled edges, and a trailing edge cut from 1.5 mm rib and then profiled.

The fin is glued to the two upper fuselage spars; the lower fin will be cut from 3 mm hardwood, embedded in the fuselage, and glued.

The movable trim rudder made of two layers of 1.5mm (balsa or hardwood), will be profiled. Don't forget the silk hinges positioned between the two layers of the rudder. The rudder's control horn (made of 10/10 plywood) passes through the rudder and is held in place by two drops of cellulose glue. A loop at each end allows you to attach the control line on one side and the return elastic cord (a square piece of rubber for micromodels) on the other. Before covering the wing, remember to attach the control lever (1.2 mm piano wire) to the base of the cockpit. This lever passes on either side of the skid and is connected to the flap by a control cable (linen thread). Also, tie the hooks of the wing struts (1 mm piano wire) with linen thread secured with glue. The single-spar upper wing is very strong and very light, and its construction is quick and easy..."

Supplementary file notes

Article (in French).
Article translation, en.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction