NEWS - JUNE 2018
Construction of the Moseppl continues. The wing centre-section,vertical and horizontal tail surfaces have been built.
The Prometheus has flown. Video is on YouTube channel:
NEWS - FEBRUARY 2018
In parallel with existing projects, we have been exploring uses for the amazing little QX-motor 30mm EDF. This lightweight powerhouse puts out around 200g/7ozs of thrust from a 3s x 450mah lipo.
Recently a small model Blanik sailplane was modified to represent the configuration used by Rhein-Flugzeugbau in the mid-1970s when they fitted their SG85 Schubgondel (Ducted Fan or "thrust gondola") to a full-size L-13 Blanik. Our results were so promising that we have been designing and building another similar model for this unit, the Prometheus 1, the full-size being a turbojet-powered derivative of the Swiss Diamant 18 sailplane.
Video of the QX-motor 30mm EDF in action mounted on the Blanik can be seen on our YouTube channel:
Below are some photos of the QX-motor 30 EDF fitted to a 3D-printed nacelle which will be used on the Prometheus. A few preliminary construction photos are included as well.
NEWS - OCTOBER 2017
From the workshop:
"3D Printing - some observations and progress - PART 2"
Design and printing of 3D components is continuing, and a new prototype has been added to the stable - the Akaflieg Stuttgart FS-26 Moseppl in 1/6 scale. FS-26 Wikipedia entry
We have been exploring the concept of using the 3D-printed fuselage shells as a support for fibreglass cloth, either inside or outside, especially for glider fuselages. We are examining this as a way to reinforce these shells to avoid three issues which can sometimes be an issue with 3D-printed structures, namely -
1. Delamination of layers and poor overall strength
2. Time-consuming inner structure (from the perspective of both design and printing time), and
3. Under-extrusion issues that can arise in thin-wall printing with internal structures.
All printers can do a great job of laying down a perimeter shell where the extruder can operate in a steady state condition. This optimum condition, where there are no issues of retraction, stringing, priming, coasting etc. allows a lot of design freedom, and is being investigated. Initial results show promise, but overall this must be weighed up against the simplicity of just pressing "print" on a 3D printer and walking away!!!
Below are some photos of the Moseppl as it has evolved, and a prototype fuselage has been printed in natural PLA:
The 1/8 scale Blanik as shown in August news (below).
NEWS - AUGUST 2017
From the Workshop:
"3D Printing - some observations and progress - PART 1"
Throughout 2017 we have been growing our 3D printing experience, and learning the new techniques required to design and manufacture components and complete flying models.
For reference, we have been using a popular and inexpensive Prusa clone, a (rebadged) Wanhao Duplicator I3 v2. Our experience with this printer has been overwhelmingly positive.
1. Plugs for vacuum-forming
We have found that 3D-printed PLA plugs for vacuum-formed mouldings are very easy to make, and perform brilliantly. The slightly porous nature of a 3D-printed part allows the PETG vac-form plastic to be drawn evenly and tightly over the surface of the plug, and yet release cleanly with little effort once the heat /suction is removed. We have made dozens of vac-formed canopies on a 3D-printed plug for our Aviojet kit, all with perfect results and no degradation of the plug whatsoever. We have also printed plugs for a variety of EDF nacelles.
The plugs do not need to be solid to have adequate strength - we have had great results using the following settings in Cura:
1.2mm thick shell......... 20% infill.......0.2mm layer height.......print temperature 215 degrees C
2. Component design
The amazing & ingenious designs of 3Dlabprint.com have certainly opened everyone's eyes to the possibilities that now exist through 3D-printing. Inspired by these works of art, we have been investigating the techniques required to work in this new medium.
We have been working with a number of the current slicing engines (Simplify3D, Cura, Slic3r and Slic3r Prusa edition) and they all have their own idiosyncrasies with respect to how they handle thin-wall design, and the documentation is sparse in this area, requiring much trial and error.
Whilst not trying to reinvent the wheel, it has been instructive to see how different approaches to the task of designing a flying model work (or don't work) in the 3D-printing environment. An indication of this is the photograph below of a small sample of trial wing components we have made to test different approaches.
One interesting feature Cura has introduced just recently is a set of three new 3D infill patterns - Cubic, Cubic Subdivision and Tetrahedral. The beauty of these infills is that they can give a result which is rather similar in appearance to a geodesic structure, and may be useful in prototyping as an expedient, rather than designing a full internal structure in the first instance.
3. Aircraft design
To assist in the design trials, we have prepared two 3D models in Rhino CAD that can be "fleshed out" with structure, which may form the basis of future model releases. These are a Blanik sailplane (which has been partially printed in 1/15, 1/10 and 1/8 scale), and an AVRO 707 delta from the 1950s which has been sized and printed for 40mm EDF or pusher prop electric.
The experiments continue!!!