We recently received a new frame for our quadrocopter and in this article we will share the results of a study of changes in the characteristics of the copter. And, of course, at the end of the article we’ll have a good bulk of video)
Over a year ago, I bought a set for $ 67 to build a racing copter ( and wrote an article about it
). This is a very addictive hobby! You constantly run into some technical limitations. That battery wants more, then the engines more powerful, the flight controller quickly and the whole process repeats cyclically. Slowly updating the elements of the system, we reached the point that we replaced absolutely everything except the frame, and, until recently, the copter looked like this:
Initially, we liked the idea of building an understated copter with all the electronics hidden in the inside of the frame. I even wrote an article
about remaking the ZMR250 frame in a “low rider”. This frame improves handling and weight (compared to stock), and most importantly, it looked cool! But over time, we began to ask ourselves about the rigidity of the frame and realized that such a solution did not suit us at all.
What does the frame affect?
We use the flight controller clone SPracingF3, which has the ability to record logs from a gyroscope and the ideal spectrogram for a good kopter is as follows:
Vibrations have a large amplitude in the low frequency region - this is the control process itself. The second characteristic area in the region of 400 Hz is the vibration from the engines.
On our old frame, which was in a cheap original set, the spectrogram of gyroscopes on the roll axis was unattainably far from this ideal:
That is, the amplitude of vibrations in the entire frequency range is so large that no pattern can be traced.
New frame and silicone pads
As a result, it was decided to switch to a new frame and we chose a rather old, but proven Martian 215 module. It is durable, it has interchangeable rays, a large amount of space for various electronics, a place to put the battery on top. More than race we are interested in freestyle, where there are no serious weight requirements, and in the end we decided that this frame is optimal for our tasks.
The very process of transferring everything to a new frame, if everything is prepared, happens very quickly and does not represent much interest. On the old frame, he weighed 415 grams, and on the new one - 385. The whole process can be seen in the video at the end of the article.
In flight, the Martian 215 is noticeably better than our old ZMR250. The kopter has become less “sausage”, a pleasant blast has appeared, the control accuracy has increased, the video has become clearer and even the sound of the engines has become more pleasant. But the graphics showed us the opposite:
If you compare the spectrogram readings of gyroscopes before and after changing the frame, the result may even become worse, but we quickly realized what the problem was.
The fact is that on the old frame we used silicone gaskets for engines:
Initially, they were installed as a tribute to fashion, and I still do not understand very well at the expense of what they allow to dampen vibrations, because the engines are still very tightly fastened to the frame with screws.
We cut out and installed the same silicone gaskets for the new frame and the noise in the spectrum of readings from the gyroscope was very noticeably reduced:
Yes, of course, its characteristics are still far from ideal, but it is noticeably better than the frame that we originally had.
Based on the foregoing, we can conclude that the frame significantly affects the characteristics of the copter and not to save on it. Moreover, relative to other elements of the copter, it is quite cheap.
But the most amazing thing is that silicone pads really work and very significantly reduce vibrations. Moreover, a bad frame with silicone gaskets noise will be comparable to a normal frame without gaskets.
I also want to boast in this article a new acquisition - receiver Eachine R051. This receiver involves connecting to an Android / IOS device and viewing a picture on the screen of this device.
The receiver has a built-in battery and supports the 5.8 GHz frequency grid. The application was installed without problems, in use everything is very simple. Only initially we had difficulties due to the fact that we did not pay attention to the fact that the wire from the kit should be connected to the telephone. Otherwise, the phone does not go into OTG-mode and refuses to reproduce the picture.
The receiver is very simple in quality and, of course, it loses to a full-fledged mask or glasses. In my understanding, its main purpose is to record a video signal, as well as the audience is much more interesting when they can also look at the picture from the copter. You can also look at this receiver at work in the video at the end of the article.
The flights themselves before and after transferring the electronics to the new frame can be found at the end of the video.
Both of these products can be purchased at Banggood:
- Rama Martian 215
- Receiver Eachine R051