Antares is a well-known racing model designed by Jaroslav Broz in 1942. It has nicely shaped streamlined fuselage, elliptical wing sits above the fuselage on a pylon. Originally powered by the IPRO IKAR 6,3 ccm spark engine, but most modelers are using any suitable engine even glow or diesel. It is quite common to see Antares powered by relatively small 2,5 ccm diesel engine (Letmo for example) or Super Cyclone or Ohlsson SP/FRV on the other hand.
My Antares was flying powered by AL-KO 7,5 ccm engine last three seasons. The engine was built from original castings by Ladislav Davidovic and I can truly say: the engine is awesome. Although quite heavier performs very well and is easy to start. I want to use another famous Czech engine for the next season and I chose the Letna 6,3 ccm spark engine designed by Gustav Busek in the late 30s.
First what needs to be done is a new engine mount as AL-KO is mounted by three crankcase screws whereas on Letna are more common mounting pads used. According to the original Antares plans, these parts are made of the aluminum sheet 2 mm thick. I only had a piece of an aviation material commercially known as “alclad” which is 1,5 mm thick, but this sheet seems to be solid enough to hold the sparky.
I took the advantage of having a CNC machine available again and drawn the exact shape. There are at least two plans of Antares available: the original IPRO-507 and redrawn plan by Jaromir Pipek. I have chosen the latter. This part was then converted to the milling paths by CAM software and we are ready to produce the brand new engine mount.
Parts are milled and we only need to do some polish. I have tried to do some fancy “brushed” finish. After that, the engine mount was completed and assembled. There is still a lot of to do like to install shorter M4 screws or to build a new fuel tank with the holder as well as to do some minor fin covering repairs. It might have seemed to be quite soon to talk about the next year’s new season, but on the other hand is better to be prepared in advance than do the fixes couple of days before the event.