jcg1541

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Gearless Heli Setup
« on: October 27, 2017, 07:29:11 am »
I have a pure direct drive build. The motor spins at 400 kv . There is no mechanical noise, only the sound of wind blowing.
Revo is on the far side of the fuselage, and the picture only shows the side servo pins of cc3d board. It lifts off at
half throttle. Bill of material and discussion are at
https://blog.mpls-phone.com/2017/09/converged-quadcopter-helicopter-device.html
.

karla

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Re: Gearless Heli Setup
« Reply #1 on: October 27, 2017, 08:55:38 am »
Thats really cool!
Have a video of the heli in action?
K

jcg1541

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Re: Gearless Heli Setup
« Reply #2 on: October 27, 2017, 10:36:53 am »
I have only throttled it to lift off from my hand when I was at the Output page of librepilot setting. No lift off from ground yet.
I don't know when I will do it.

I am thinking about refocusing my design direction because my goal right now with heli is to do illegal FPV building
urban proximity diving, like so many youtube videos have done with quads. So, I need a collective pitch 3-servo system
to keep a constant RPM to store large angular momentum while the heli is free falling at zero collective pitch. The
picture's main frame is a fixed-pitch, 2-servo system. But I will continue pure direct drive gearless with the 3-servo system.

Thats really cool!
Have a video of the heli in action?
K

Re: Gearless Heli Setup
« Reply #3 on: October 27, 2017, 12:38:32 pm »
It might be handy to enable RTB on failsafe with TakeOffLocation set to a distant fixed place so you can switch off the transmitter and retrieve the copter later from a known location.   ;) ::)

Of course that means that it must be completely set up for autonomous GPS flight.
« Last Edit: October 27, 2017, 12:43:14 pm by TheOtherCliff »

karla

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Re: Gearless Heli Setup
« Reply #4 on: October 28, 2017, 11:18:54 am »
So, I need a collective pitch 3-servo system to keep a constant RPM to store large angular momentum while the heli is free falling at zero collective pitch.
The picture's main frame is a fixed-pitch, 2-servo system. But I will continue pure direct drive gearless with the 3-servo system.

Lets see if I follow,
I understand the motor part and no main shaft, great, and you took the main rotor head unit and gearing from a small size heli with 2 servo system control from something like here
https://www.horizonhobby.com/200-sr-x-bnf-with-safe-reg%3B-technology-blh2080
and now you look for a 3 servo configuration to achieve the goal of gaining greatest momentum while free falling?

I think the 'gaining momentum as falling' has nothing to do if you have a 2 or 3 servo system installed?
But if you can live with cost of the components of a full 3 servo configuration you should do it since so much proven configurations and settings can be used.
Also, for your build with small power you may get away with a tiny gps and the internal mag of a revo nano unit to make a RTB function. That would help a lot right?

jcg1541

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Re: Gearless Heli Setup
« Reply #5 on: October 28, 2017, 06:11:39 pm »
You got most of it. The main shaft's diameter is exactly the same as the main motor's shaft's.

For the stored angular momentum part, it is "angular momentum" of the inherent collective pitch system that allows 300 foot free-fall and yet pull out at the last second with full thrust using the full spool-up rpm speed. It is rotor's "angular momentum", not the craft's "momentum".   The variable pitch is critical for illegal urban diving because fixed pitch craft spools down to idle rpm during free-fall of 300 foot drop, and the craft can't spool up fast enough to pull out alive in under 1 second. It is stunt video, not suicide video. Prime example is illegal trump tower diving . It can't be done with fixed pitch helicopter because the idle rotor won't spool up in 1 floor drop after a 50 floor free fall.

But quads with small angular rotor momentum will never get long duration military missions that is exclusively helicopter because when we half the rotor diameter, the newton laws half the fuel economy. If we stretch a stunt multi rotor's propeller blades to twice length, it will look like a cargo helicopter, like the Chinook, and won't be able to do the stunt dive.

Collective pitch 3 servo systems are at the sweet spot of both long duration missions and stunts. The dawn of this new trend is this other video .

I think the 'gaining momentum as falling' has nothing to do if you have a 2 or 3 servo system installed?
But if you can live with cost of the components of a full 3 servo configuration you should do it since so much proven configurations and settings can be used.
Also, for your build with small power you may get away with a tiny gps and the internal mag of a revo nano unit to make a RTB function. That would help a lot right?

karla

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Re: Gearless Heli Setup
« Reply #6 on: October 29, 2017, 02:17:46 am »
Ah, now I see what you mean.
Yes a fixed pitch system will have to spool down otherwise it cant fall straight down but would drift away from building.
I remember several years ago I saw a video of a 450 size heli doing a free fall along a high building... left me dizzy :)

edit, found the clip

« Last Edit: October 29, 2017, 07:37:34 am by karla »

jcg1541

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Re: Gearless Heli Setup
« Reply #7 on: October 29, 2017, 08:27:08 am »
I also love this clip dearly.  The same pilot now has a new youtube channel called picoflyer . He doesn't
do illegal dive bombing over crowded places now, only smooth dives. When I was younger, I used to do
parking lot flying with stick fixed wings and attracted local police. They were not seriously concerned
because the craft was under 200 grams, and any one could see that it was harmless when they approached.
I am very cautious about keeping craft weight under 250 grams.

Ah, now I see what you mean.
Yes a fixed pitch system will have to spool down otherwise it cant fall straight down but would drift away from building.
I remember several years ago I saw a video of a 450 size heli doing a free fall along a high building... left me dizzy :)

edit, found the clip

« Last Edit: October 29, 2017, 08:51:56 am by jcg1541 »