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Test flights

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:heli control

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:

heli_acc takeoffThe 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.

heli_gyro

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!

heli_acc_fftHere 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…

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