This has been a very exciting weekend for our team, we have been planning this activity for a while, but for one or another reason had to postpone it.
Eventually this weekend we did all the necessary weighing to see how our design compares with original Sandlin’s Goat glider and whether our COG is in the required range.
This time the glider assembly took about 3 hours including preparations for the measurements and some minor upgrades, whereas disassembly of all structure took only 1.3 hours. We are estimating that in normal conditions the assembly should not take more than 1.5 hours, that is when everything is in place and there is no need to search for anything. This task is pending, but when we will have the trailer ready then all the parts will be in the same place and there won’t be any hold-backs.
Weighing was performed at two points: main wheel and the tail skid.
After the measurements the conclusion was that we have similar weight distribution as the original Goat. The centre of gravity including the various pilot weights and the rescue system is within the range of 24%…28.2% MAC (Mean Aerodynamic Chord) making the glider predictable and easy to fly. As per our design the seat is lightweight and thin allowing the proper position for taller and heavier pilots. For smaller and lighter pilots we can add 5…10 cm padding in order to shift the pilot forward to match the required CoG position when necessary.
After the work was finished we made another review of the design and spotted some potential upgrades. During the glider controls tests we have observed that the torque tubes used for aileron control do not hold the torque well enough. Therefore we decided to replace them with wound carbon tubes which are specifically designed for torque transfer. Tubes will have multiple layers 90-degrees and multiple 45-degree angles layers making them stiffer for torque transfer. Another upgrade would be changing the front nose tube to something more durable and stiffer as the people have tendency to hold to it while seating.