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making your own blades ¡@ |
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making the main body
making the cyclic control system ¡@ an introduction to electronic components building an airborne video system ¡@ |
After learning from bitter experience, my skill on making blades finally become little bit more proficient. Hope I can share my knowledge with you which might prevent unnecessary setbacks that you may encounter just like me did. My motto is: "build the blade root strong" Ok..here it is:
Materials needed:
These blades are symmetrical (allow inverted flight) with 32mm chord, 225mm length and 4.5mm thick. Both the bolt hole and the maximum thickness is located at 28% chord point. the total weight of each blade is 9.6g including tip weight.
First of all, draw the airfoil on both ends of the balsa wood which can guide you through the sanding process. Use a sanding block to sand out the airfoil. Make a hard wood rectangular block 28mm*8mm (4mm - 4.5mm thick). cut out a slot (16mm*8.2mm and 5mm from the leading edge) on one end of the blade to house the hard wood block. Use 5 min epoxy to stick it to the slot. cut away any excessive epoxy before it is fully dried with a cutter. Cut out another slot on the next end to room the tip weight (3.5g for flybarless blades and 2g for an ordinary blade) as close to the root tip as possible. Some epoxy must applied to hold the weight in place.
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Please be minded that my blades are made form uniform density material (one piece balsa wood). If no tip weight is added, the CG (or centre of gyration) would be located far behind the centre of lift (about 25% chord point). Practically, CG should be placed at, or ahead, of the centre of lift. This helps to prevent the forming of a twisting force that may set off an oscillation called flutter. For this reason, tip weight must be added in my design |
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