I had some bad experiences with the main side frames of the Eco. Firstly the stock frames are far too flexible so almost from the start I had purchased Ikarus Carbon Frames. However in a light crash these simply split in front of the motor taking the motor base plate with them and a good portion of the helicopter!

I purchased Aluminium side frames and rebuilt the helicopter, during the first flight whilst trimming out I landed a little heavy and the frames split where the landing gear is jointed. This area is very week on all the frames I have tried, I decided to try making some frames myself using 1.5mm Carbon Sheet.

The AutoCAD R14 drawing files for the frames are available for download from the Analysis page.

The first task is to scan one of the original side frames at 100% resolution. This is then imported into AutoCAD as a bitmap image.

To check dimensional accuracy I drew a reference line for a known measurement and scaled the drawing to this point.

I then printed out the scan at full scale and laid the frame on top to check, in my case it worked perfectly.

I was then able to draw my required frame using the scan as a reference.

Areas that I tried to improve with my design where as follows :-

1. Improved strength around the top and bottom bearing areas, I increased the width of the frames in this area, I also increased slightly the distance between the two.

2. Increased the depth of the member for the landing skid mounting points, to take them impact of heavy landings more effectively.

3. Increased the distance between the tailboom clamps, to add a little more rigidity to the tail

4. Protective / Strengthening hoops across the top of the motor to cut down on the possibility of breakage in the weak area ahead of the motor.

I made provision for servo positioning and an area to position the receiver on the left side.

As the Carbon Sheet is 1.5mm thick I wanted to remove a fair amount of material to keep wait down, at the same time retain strength. I went for a diagonal 'Geodetic' pattern which I felt fulfilled what I wanted.

I also though it looked good which is just as important!

I applied the usual principal of printing out the templates full scale and using spray mount to position on the Carbon Sheet.