The heli underwent some test flights. Unfortunately I have no videos (I cannot do two things paralelly 😉 ) but at least some results are here.
But first of all, lets show how the heli is controlled. I am using a standard USB joystick and a computer. It is not a good way to control heli outdoors but on the other hand the heli is intended to be a remote controlled UAV (one day). Thus some advanced “ground station” is vital.
Here goes the picture:
In the future I am going to make it a bit more compact and mobile (I’ll probably use a tablet 🙂 ).
Anyway, when it comes to flight results, here it is.
Manual control works fine and heli immediately reacts on pilot’s commands. But IMU/INS is surpassing some hurdless. There is a huge problem with vibrations. Main rotor causes massive high frequency vibrations. The INS board is placed in a mechanically damped platform in all 3 axes but still, measured vibrations exceed 6 g. High frequency is not such a problem as it can be filtered but another problem are low frequency vibrations around 5 Hz – heli is essentially shaking in all three axis. This can be clearly seen on the artificial horizon.
Here are some graphs showing vibration problem:
The figure shows acceleration in all 3 axis during a (slow) takeoff. It can be seen that vibrations are huge. Another problem is influence of vibrations/shaking on the gyroscopes. They are working around their limits and potentially cannot handle a sudden rotation.
During fast rotation around yaw axis there are significant vibrations around other two axes. Gyro’s sensing limit is around 6 randians per second. Vibrations are almost 3. And again, this is for 3axial mechanical damping of the INS platform!
Here is some brief frequency analysis of the vibrations. It can be seen that vibrations start at around 20 Hz.
Compared to quadrocopter, helicopter is a wild beast…