Aiguillon (oz14493)

About this Plan

Aiguillon. Radio control scale PSS model. Wingspan 1914 mm.

Note the 'original' drawing here is the CAD zip download (in dwg format). That's the file that Giuseppe sent us, and that is his design, his work. The PDF file you see here is really just a taster, a PDF file in this slot for Oz users who don't have a CAD viewer.

Direct submission to Outerzone.

Quote: "A PSS rendition of a strange Swiss prototype called Aiguillon on a simple drawing. Ciao, Beppe"

Update 12/4/2023: Added article, from 'On the Wing' Dec 2004, thanks to Martin Huebner.

Quote: "Hello Steve, Hello Mary, concerning Aiguillon (oz14493) I like to send you the story behind this model airplane [see article file].
The used airfoil SN42 is designed by Simone Nosi and will be found at the Profili airfoil database: https://www.profili2.com/eng/lista_profili.asp
Greetings"

Quote: "Beppe Ghisleri’s Aiguillon: Our Italian correspondent, Beppe Ghisleri, has been flying a Swiss N-20 Aiguillon on the slopes of Italy and Austria for over a year. While Beppe intended to have a PSS model, that’s not quite how things worked out. Here’s the story...

The idea: Beppe first saw the Aiguillon in the second issue of Dave Jones’ Quiet Flight International, July 1994, in Simon Cocker’s PSS column.

There was a small three-view and a short write-up which described the 1951 prototype as using four by-pass engines adapted from Armstrong Siddely Mamba turboprops. The prototype did fly, actually making a few test hops before the project was abandoned.

Beppe had no interest in the N-20 Aiguillon initially, but about two years ago he was going over some of the early QFI issues, spotted the N-20, and decided he would build one for PSS.

Luckily, the advent of the internet made finding documentation for the model relatively easy.

Additionally, Beppe was able to contact a Swiss PSS modeler, Reto Schmid, who sent him detailed three-views of the N-20, reproduced on page 20. Together with photos of the prototype in a museum, where it now resides, Beppe had sufficient material to start his project.

Planning and design: Because the model was to be flown in slope lift, and hence designed to be a glider, adjustments were made to some of the dimensions. The model is therefore not exactly scale. Beppe enlarged the wingspan of the outer sections a bit to increase the wing aspect ratio. Even with this change, the aspect ratio is rather low for a glider. The fin and rudder have also been slightly enlarged to match the higher aspect ratio.

Beppe’s N-20 is a relatively large model. The fuselage has an overall length, nose to tip of fin, of 1.42 meters; the wingspan is 1.92 meters and the wing area is 87 sq.dm. The completed model weighs 3200 g ready to fly.

The wing uses an airfoil designed by another Italian modeler, Simone Nosi, the SN42. This section is 8% thick and has a near zero pitching moment. Beppe used the Panknin spreadsheet on the B2Streamlines web site to compute the needed wing twist. Two degrees of washout is used, starting at the wing outline break at roughly half span. There is no twist in the inner panel.

The SN42 wing section and about 3000 other profiles can be downloaded from the Profili web site. (See References.)

The MAC was determined with Planform-Analysis Version 1.4 by Greg Ciurpita based on John Hazel's Liftroll Spreadsheet. The CG was set to 10% ahead of 25% MAC, a static margin of 0.1.

Construction: The fuselage is from blue extruded polystyrene shaped and carved and covered with 200 gr./sqm. fiberglass.

The wings are from white foam sheeted with 0.6 mm obeche veneer and covered with 40 g/sq dm fiberglass. Some carbon tissue is laid on the underside to help resist landing bruises.

Between the foam and the veneer, on the trailing edge, some carbon tissue helps maintain the form of the profile which is very thin.

Every half wing is built in two pieces, individually sheeted and later joined with two short 3 mm thick poplar ply reinforcements..."

Supplementary file notes

Article.

CAD file

This plan is available for download in CAD format.

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