version du 01/01/70

The tube...

A piece of tube of PVC water pipe, some aluminium sections... and here is a solid and quickly built plane !

This very rustic plane,, is freely inspired from an American kit the " sturdy birdy " described a few years ago in model mag'.

I equipped it with a structure wing right for the pleasure of cutting out the ribs with my CNC milling machine... A polystyrene wing would be certainly easier to realize!

The plane completly equipped weigths 1800 g, for a scale of 150 cm.

The spare parts view gives you an idea of the techniques of construction: nothing complicated !



The tank, protected from the vibrations by four self-adhesive tapes of E shaped rubber for windows insulation, is simply strongly pushed inside the PVC tube. One notices the throttle control link exceeding in front. One also distinguishes the servos support in the distance... The leg is a sheet of aluminum folded and screwed under the fuselage. The wheel base is about 26 cm, the bottom of the fuselage is to 15 cm of the ground. The throttle control servo is located just behind the tank. It is assembled on a small wooden support screwed through PVC tube at the level of the nose gear. The U aluminum section is prolonged up to the level of the legs to consolidate its fixing.

The engine, a 4 Cm3 (OS25 SFR on the photograph) is assembled on a standard support. The support has the good idea to enter without too much play into the tube. Jo just need to realise and stick a small PVC hold on two sides. It will be solidarized with the fuselage via four tapping screws. One will benefit from it to adjust the stitcher and anticouple (approximately 3).

The servos of depth and drift are fixed on a small support out of rods of samba which fits on the tail aluminum rail. One will chose the distance to obtain a correct centering before fixing the support by a small screw on the rail.

Nice, from here, isn't it ?


The wing is kept in place by a a carbon stick set inside the leading edge and a screw nylon at the trailing edge . It is posed on 2 E shaped rubber tapes to limit the vibrations and to compensate for light tube round shape.

The attaching part is a fall of PVC tube bored before hot folding. The part is then stuck on the fuselage then riveted (or screwed) for more security.


The rear whell is a mobile one via the axis which crosses the fixed plan to fall on the level of the rudder articulation

An aluminum U shaped 20 mm piece comes to be embedded in U of tail to guide the rotation of the axe.(On sees this part on the first two photographs


One distinguishes, in front of the caster one of the wood screws to fix the stab unit and rudder. The section aluminum is sandwiched between the two.

The stab unit + rudder is very simple! The aluminium beam has a certain flexibility (not to say an unquestionable flexibility...) in torsion; but that by no means disturbs qualities of flight of the bird.

The foot of rudder consists of a small piece of samba wedged in force in the section out of U the drift is stuck to the square then reinforced by two balsa triangles.

General dimensions are provided on the scheme below. The wing will be attached to the last moment to ensure a correct centering. With my wing of structure whose dimensions are : 150 cm x 23 cm of cord. Centering is correct with the coasts (in cm) indicated on the plan. Gravity center is located at the levek of the spar.

The wing profile, is a IDNKW-01 (I do not know what!) resulting from a plan which remaining in a corner of my desk. Joke aside, it is probably a CLARK Y who has the advantage of accomode with the under-surface parallel with the stab. Here the diagram of the two types of ribs used (with or without formwork of the back part, knowing that the wing is cased top-below on all its front part). I cut out my profiles directly using the numerical milling machine, the thickness of the feature corresponds to the path of cutter, one thus preserves only the interior of the gauge. Do not forget all either to bring back on the scale so that the cord makes 23 cm...

To conclude, some words on the flight:

The taxiage is a pleasure thanks to the direct whell, but considering the power of the OS25, one can be satisfied with a simple end of piano wire if one wants to still simplify (it is the option chosen for the sturdy birdy kit!

Despite its 1,8 kg, the bird takes off in a few meters and has a very healthy behavior. The wing in double dihedron confers a good stability to him. The roll order is a little weak, the ailerons of the size of the triangular rod of trailing edge are undersized a little bit, so that the barrels are soft, very soft...

Setting it in curve can be carried out simply with the ailerons, one has a very calm curve then. Or well, in three axes with a blow of rudder and there, it is a pleasure, one can almost turn on the section and it is an excellent drive for those who want to pass to the ailerons.

The generous elevator makes it possible to pass the loop in a handkerchief...

The flight back is possible but there either, it is not its vocation... maybe the clark Y !

The plane in the air has a trapanelle look, rather pleasant to see, able to slowly flight, but laid out to provide beautiful accelerations at full gaz.

Here, have fun, during construction, in flight, and on the ground by seeing the head of the buddies!

Send me a photograph if you build one of them, you will be published on AEROPIC!