Works as a stand for propellers testing. Doesn't fly any more.
1.9 RF RC for DragonFly 9093 (by Syma).
This helicopter does not fly (right out of the box), or rather it flies, but by itself. And the following picture provides an opportunity to guess why this is happening. Guessed?
The frequency (27.145MHz) is wrong. It belongs (almost always) to a discrete radio control that only turns motors on and off. And if we open the hood, then in the middle is the well-known RX2 chip, which can control 2 reversible motors.
It reminds me of a good time when markers were not erased from chips by manufacturers.
An additional feature of this chip allows the motors to run at 50% power (PWM) or at full power ("turbo"). But this very poorly helps to control the helicopter. This is a nightmare of 'first' & 'fast' design from year 2006.
The back of the board is for reference only. We can assume how this works. A power transistor for the main motor delivers full or 50 percent of power. For rear propeller, the power is limited by a variable resistor that needs to be adjusted so that the helicopter does not spin in the air. This is an analog signal, so the second power transistor is equipped with radiator.
I can’t believe that flight control is done that way (on discrete RC IC), but we have what we have. Let's stop on this, since the electronics of this helicopter are not interesting at all : )
* But it can be used for ... or completely unrelated.
Of course, this toy is not designed to fly. I use this as a stand to test different blades after they are printed on a 3D printer.
This is a very cool process (if you know what you are doing). Just a few examples.
It all started with the fact, that I decided to check whether the helicopter can fly with half the top propeller (the other half is replaced by a counterweight, of course).
The result is, the half of propeller works no worse than a full one. A helicopter doesn't care. You pay by extra vibration, but for that, you can save some battery power. In short, with a half of propeller, a helicopter (quad-copter) can spend, in average ~10% more time in the air.
It is it. Enjoy.
*** Any inaccuracies on this page will be corrected, if you let me know ( highlighted :) ***