Yesterday we had a beautiful winter day in Fairfield County, CT, so I went out with my kids to do some helicopter weight lifting. It’s much more fun than lifting weights at the gym.
My oldest son Samuel is designing a robotic landing gear for a helicopter. The estimated weight of the gear is about 600-700g, so we wanted to see if my relatively small 450 size heli could carry the extra weight. Here is a picture of the heli, a heavily upgraded HobbyKing HK 450:
The first question was how to attach the weight. There are two options: attach the weight directly and rigidly to the frame, or tether it to the heli with a line. Rigid attachment bears the risk of screwing up the gyro, plus the heli might tilt on lift-off if the weight is too much. Tethering on the other hand gives you a swinging load, which is difficult to handle, too. In the end we decided to tether a cardboard box to the frame, and use a long string so the heli can get an altitude with a good margin of safety.
We worked our way up from 220g (piece of cake) to 430g, 625g, 845g, 1120g. At 1290g the load could no longer be lifted off the ground. We dropped down to 1200g, which the heli could lift a few feet off the ground, but it could no longer gain altitude.