Styx (oz9209)

About this Plan

Styx. Radio control competition aerobatic model.

Quote: "Top aerobatic model from France. Styx, by Pierre Marrot.

In case you think the 'Styx' is just another shoulder wing model, just take a closer look, because a geat deal of 'think' has gone into this design. The wing, tail and engine thrust line for instance are on a common datum. Take a look at the wing section as it nears the tip - it looks strange, but is obviously there for a purpose. In all, it is quite a remarkable airplane, although we must admit, it helps to fly like Pierre Marrot!

THE Styx came about because I wanted a model that would be a smoother flying, improved version of my Satanas (Corsica 1967).

The fuselage is basically that of the Satanas with the only modification being a deepening of the profile to get more lateral surface. This, of course, is necessary for knife-edge flight, but also helps the model to fall straight through with no 'wobbling' on the down side of double stall turns. The rudder has been enlarged slightly to give better yaw stability while retaining the other good qualities of the Satanas.

I used a symmetrical airfoil from root to tip, since I feel this type of wing is more stable. The tips won't stall before the centre section, helping to prevent snap roll on landing approaches. This is even more apparent when flying in windy weather. The thick wing does induce a lower drag ratio, but the drag helps you to maintain a more constant speed throughout all your manoeuvres. I stayed with conventional ailerons on the Styx. I also kept them in-board of the wing tips to keep them out of the tip spillage where they would only induce drag while being ineffective. There is also turbulence at the tips of the wing which can induce aileron flutter.

The ailerons are hinged on the centre line. This makes it a simple matter to get any degree of differential aileron throw (in either direction) simply by changing the point of connection of push rod to the aileron horn. Several horns can be prepared with holes in various places relative to the hinge line, or one horn with several holes can be used. See plans for an explanation of how the differential is obtained.

The shoulder wing allows smoother take-offs and landings on a strip, since the boundary layer of air under the wing is weaker or more elastic than that of a low winger. This leads to a take-off run and lift-off that is predictable and controlled by the flyer rather than an abrupt leap into the air at an excessive angle (sometimes up to 40°). The latter is seen all too often on low wingers having a negative wing incidence or angle-of-attack with the ground..."

Styx, RCM&E, June 1970.

Direct submission to Outerzone.

Update 23/09/2017: Added alternate (maybe clearer) scan of the Styx design, as published in MAN April 1969, thanks to RFJ, Circlip.

Supplementary file notes

Article pages, thanks to RFJ.
Alternate plan scan.

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