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May 20, 2019, 07:39 AM
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Cambered from a coaxial (toy) heli?
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May 20, 2019, 10:14 AM
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Woga65's Avatar
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Quote:
Originally Posted by hamburger
Cambered from a coaxial (toy) heli?
From the Skyrush Teryx 450. That was one of the rare non-toy CP koaxial helicopters. Spare parts are still abaulable.
May 20, 2019, 11:08 AM
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The Lite Machine helicopters had under camber blades but parts for it may no longer be available. The under camber really increases the CL/CD but is not as good for forward speed nor for flying inverted.

I designed the Air Scooter blades based on the Lite Machine blades but with more twist. Should have know better because the increased twist causes more drag. To make a long story short, I ended up with all of the unsold inventory for the Air Scooter Helicopter and have at least a hundred sets of right and left hand blades just collecting dust. They are the same blades that Al and I used on our attempt to build a collective quad.

Gene
May 22, 2019, 04:07 AM
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Quote:
Originally Posted by rchopper56
... Our main problem was that we were using a gear box for reducing the rotor rpm, kept stripping gears. Tried to slow down the control response but to no avail...
Quote:
Originally Posted by rchopper56
Spooling up was not the problem. The sudden change in collective was a sudden strain on the transmissions. Collective pitch was used to control pitch and roll and yaw. That why I said that I was trying to slow down the response of the servos. No RPM change was used but the controller was meant to control an ESP for a motor.
Thats weird. I have not had any problems with gears.
https://www.rcgroups.com/forums/show...brushless-quad

Nighter 3D printed gears stripped ...
Geared Monster-Tricopter - maiden (1 min 11 sec)


... nor the gears i scored from rc helicopters and rc cars.

Geared brushless Monster-Tricopter - gears and shafts adjusted (1 min 22 sec)

BiCopter - TriCopter - QuadCopter - Geared brushless drive - Will it fly? (2 min 5 sec)



Quote:
... I think that Wii came out several years before 2010. People had just started using three simple electronic rate gyros to control a tri copter. Then someone removed the gyros from a Wii and started playing with them.
...
Between 2000 and 2010 I repeatedly tried to get anything into the air but have been inexperienced and much too impatient so i failed.
Last edited by Woga65; May 22, 2019 at 04:06 PM.
May 23, 2019, 12:15 PM
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I was using the second stage gears from the failed Airscooter model. It was just too easy to use for what we wanted and thought were up to the task.

We we were using digital Hitec servos that had just come on the market. We adjusted their travel to about 25% but that was still a shock on the Airscoot transmission.

I quickly redesigned a new transmission but by this time, Al was diagnosed with stage 4 cancer. So development stopped.

Gene
May 26, 2019, 06:56 PM
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Woga65's Avatar
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To separate the 8.4 V that is provided by the BEC to power the servos and the flight controller from the 5 V that the flight controller (Omnibus F4 pro V3) provides via its internal BEC on its servo / ESC leads, i had to make my own distribution board.

Since i do not know whether the low voltage section of the old Kontronik ESC needs to be external powered i also passed 5V from the FC to the ESC.

If it does not work due to servo-noise on the power lines i will power the flight controller directly by one of two 5s lipo packs.
May 29, 2019, 11:25 PM
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Didn't know some servos could take 8.4 volts. I'm guessing the 5v from the FC wouldn't provide enough amps for servos anyway if 5v was enough for them. Going to have a power distribution issue myself soon so this is good to see how you resolve it.
May 30, 2019, 02:30 PM
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Quote:
Originally Posted by RCvertt
Didn't know some servos could take 8.4 volts. I'm guessing the 5v from the FC wouldn't provide enough amps for servos anyway if 5v was enough for them. Going to have a power distribution issue myself soon so this is good to see how you resolve it.
Yes, servos for heli use often can run on 6 V, 7.4 V or even 8.4 V.
The servos can run on 5 V but the FC cannot provide sufficient current. Also servos can cause huge noise on the power line. This is most likely related to the brushed motors most servos are using so the brushless servos i am using may not cause those noise issues but who knows.
May 31, 2019, 08:31 AM
Thermite + ice = Big boom.
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Brushless servos will still cause some noise. If they support 8 volts or so, you may get more power (faster response and/or less current draw) running them with that much power. I see no reason not to (other than the complexity of actually getting 8v to them).

Some extra capacitors on the 5V bus will also help smooth out noise
Jun 04, 2019, 01:47 AM
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Woga65's Avatar
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Last night i made some custom code for Betaflight.
It is now possible to use a motor (not servo-) mixer to control a swash plate. Also it is now possible to config a gyro sensitivity channel via CLI.

To achieve this i added two cli variables. One allows for per output servo reversing and the other sets the gyro sensitivity channel to OFF / AUX 1-4.

Video - Servos controlled by motor mixer - Servos outputs 1 and 3 reversed via cli.

Betaflight can now do CCPM swash plate mixing (0 min 49 sec)
Jun 07, 2019, 05:38 PM
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Betaflight powered helicopter


After a deep dive into the servo mixing capabilities of Betaflight (Thanks to mikeller for his assistance!) I reverted the code changes - except the changes I made to have a gyro sensitivity channel - and setup a custom servo mixer.

First tests on the ground:

Betaflight powered helicopter - first tests on the ground (1 min 13 sec)
Jun 09, 2019, 06:10 PM
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Almost done!


As mentioned before moving the servos quickly causes receiver brownouts if the FC is powered by the same BEC as the servos. So i will power the FC directly by one of the two 5s lipo packs. To do this i will use the balancer connector so i will not have to solder an extra connector to the lipo.

This is how it looks at the moment:
Jun 11, 2019, 04:33 PM
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Not a single cotter lying around here. Fortunately the girls frequently lose hair pins in my studio!


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