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Mar 08, 2018, 06:01 AM
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RX80. A printed size 80 helicopter is the final version.

I want to thank Mike Jennings (MikeHRC) for the translation!!!

Russian version and

And so, at last the turn came to the final version of the world's smallest flying helicopter on brushless engines, with the drive of the tail rotor through the shaft.

About the trial version, you can read in the previous part

The final version is very much stretched over time. There was another intermediate version of the frame, which I did not collect, because by the time I received the seal, I had already come up with a better version.

As you can see, the helicopter has acquired normal, full-fledged skis. The helicopter HiSKY HCP80 became a ski donor. Fragile skis were the main problem of the trial version and I managed to solve it quite successfully.

The skis are fixed by 3 screws to the bottom of the frame.

The new frame has also undergone changes.
The frame itself became shorter by 4mm and lighter by 0.5g. Some elements of the frame became thinner. The elevator servo changed places with the main engine. This was done so that during the assembly it was not necessary to reverse the servo itself, for the correct operation of the helicopter.

Well, the most important change in the frame is the attachment of the tail engine. More precisely, the lack of attachment.
In the final version, I decided to proceed with the tail motor mounting radically, on the principle of no fasteners - there are no problems.
In the market there is no engine of the 1102 type with a suitable motormount. In the trial version, I used the HP02 engine. Its motormount is also not suitable for normal installation in the frame of my design, and in the trial version I adjusted its position for a long time for the normal operation of the tail.
Therefore, without thinking twice, I decided to integrate the tail engine directly into the frame.

For this, I dismantled the HP02 engine, and mounted the stator of this engine into the frame. The stator itself had to be modified a little. The hole in the stator for the motormount is 5mm in diameter, and the outer diameter of the motor bearings is 4mm. As a result, the thickness of the wall between the bearings and the stator is 0.5mm. This thickness is quite enough for aluminum motormount, but for plastic this is not enough. So I left the 0.7mm wall thickness in the model, and the hole in the stator bit wasted.
The stator itself is tightly inserted into the frame and fixed with a colorless varnish. Also in the frame were installed 2 bearings, although, probably, could be limited to one.
This solution allowed to shorten the frame dimensions, making it more compact, and also greatly simplified the adjustment of the position of the drive shaft for the tail rotor.

Along the frame, in the final version, the dimensions of all the servo drives diminished.
In the trial version, I shortened only elevator servo, and in the final version I decided not to waste time on trivialities and reduced all servos.
The rear cover of the servo drives was threaded with a file holder of 0.4 mm, and the latch was reworked on the central part, under the new size of the back cover.
They were also reduced by 1mm along the width of the rocking chair and shortened the output shafts of the servo drives. As a result, the dimensions of the servo drives were reduced by 1.4 mm.
This in turn made it possible to increase the density of the assembly and reduce the dimensions of the frame.

Otherwise, this assembly repeats the assembly of the trial version, with all its changes, except that in this assembly I installed the flight controller from the WL V977 helicopter, but this does not change the essence. A more detailed description of the components can be found in the previous section.

I also adjusted the dimensions a little and changed the shape of the tail case. Made it a little thicker and tighter.

In the final version of this helicopter I decided to use the sliding connection of the main shaft - the main gear.
This solution has proven itself in the older models RX100 and RX120, and I implemented it in this model too, since with the new, more powerful main engine, the main shaft with the slot did not last long and crashed.
In the main gear I cut the slot and put a bandage on it, in the role of which the rim of the bearing protruded.

Comparative sizes of the three final versions of the helicopters RX80, RX100 and RX120

Well, a couple of group photos.

The final version of the RX80 helicopter received a more balanced appearance, thanks to a shorter frame and lesser skis.
The helicopter itself became a couple of millimeters lower and more beautiful. The remaining dimensions remained the same.

I planned to reduce the weight of the final version by at least 1 gram. I will say right away the task was not easy.
The weight of the trial version with the HP03V2 motor was 29.9.
The final version of the helicopter weighs 29.2 g. The
weight of the final version was reduced by 0.7 g, which is quite good.

The helicopter is flying quite cheerfully and steadily. The tail works even better than the older brothers.
In general, it's time to master indoor aerobatics. In the meantime, the video flight on the street.

Batteries with high current yields did not last long and unfortunately lost their former "glory". Now they also work as two-year batteries from V911 to 200mach. So with a good battery, the helicopter will be even more smart.
In the video, the helicopter flies on a battery from the V911 which is already over 2 years old.

RX80 - final version (4 min 19 sec)

Small update

Printed main rotor hub, the swash plate and the main rotor grips

Аfter the assembly, I decided to paint them with a black marker

I really like the result. Vibration of the main rotor disappeared. I made the rotor grips a little longer, this increased the diameter of the main rotor.
I think that this will have a positive effect on the flight.
I do not know how long these details will last, but I hope that for a long time)
I already had a positive experience with a printed main rotor hub in the V911 helicopter.
Last edited by remlen; Dec 10, 2018 at 03:04 AM.
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Dec 13, 2018, 04:24 AM
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RCvertt's Avatar
Very innovative project.

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