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General => General Technical Chat => Topic started by: Moshly on July 18, 2016, 09:28:33 am

Title: Crazy 'Manned Multicopter' must see
Post by: Moshly on July 18, 2016, 09:28:33 am
Wow, this guys is both crazy and a genius (skip to 4:40)
https://www.youtube.com/watch?v=ALYECvs06XI (https://www.youtube.com/watch?v=ALYECvs06XI)
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Kilrah on July 18, 2016, 09:42:03 am
Wouldn't say "genius" as there's really nothing fancy in there, but crazy for sure for daring to use such a thing with known unreliabilities and no backup system...
Title: Re: Crazy 'Manned Multicopter' must see
Post by: donotdespisethesnake on July 18, 2016, 09:45:14 am
Basically he's invented a flying coffin, he just needs to add the lid.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: retrolefty on July 18, 2016, 11:22:17 am
Basically he's invented a flying coffin, he just needs to add the lid.

 Yes, who the hell does he think he is, one of the Wright brothers.  :box:
Title: Re: Crazy 'Manned Multicopter' must see
Post by: GEuser on July 18, 2016, 11:31:23 am
That was really good , from what i could figure out he has cross-linked the throttles to the joystick i think ..
Title: Re: Crazy 'Manned Multicopter' must see
Post by: StuUK on July 18, 2016, 11:43:36 am
Wouldn't say "genius" as there's really nothing fancy in there, but crazy for sure for daring to use such a thing with known unreliabilities and no backup system...

Like having the engine kill switch near his feet  :scared:
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Muttley Snickers on July 18, 2016, 11:49:26 am
I thought it was very good, excellent even.   :-+

He could start a hedge trimming franchise, cut and blow in one go.   :)
Title: Re: Crazy 'Manned Multicopter' must see
Post by: DenzilPenberthy on July 18, 2016, 12:54:40 pm
Like having the engine kill switch near his feet  :scared:

Which will be of limited use when, after a millisecond's inattention, he loses both legs at the shin to those props :/

Title: Re: Crazy 'Manned Multicopter' must see
Post by: StillTrying on July 18, 2016, 03:20:26 pm
For this thing to lift off, each propeller would have to be providing about 15 Kgs of thrust, they don't look or sound anywhere near that to me.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Towger on July 18, 2016, 03:26:11 pm
Just watching him sit down in it (from the head cam) was hair raising. 
He appeared to be alone in the clearing, not recommended when playing with a toy capable of badly hurting you in many different ways.  Even an open field would be safer.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: zapta on July 18, 2016, 03:59:42 pm
Just watching him sit down in it (from the head cam) was hair raising. 
He appeared to be alone in the clearing, not recommended when playing with a toy capable of badly hurting you in many different ways.  Even an open field would be safer.

Still a safer location than this Maker:

https://www.youtube.com/watch?v=l422VlRE4xs (https://www.youtube.com/watch?v=l422VlRE4xs)
Title: Re: Crazy 'Manned Multicopter' must see
Post by: langwadt on July 18, 2016, 04:52:45 pm
...no backup system...

so just like a regular helicopter
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Kalvin on July 18, 2016, 05:16:29 pm
...no backup system...

so just like a regular helicopter

Helicopters have a capability to land (even safely) using autorotation, but this one will drop from the sky like a stone.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: nctnico on July 18, 2016, 05:18:56 pm
...no backup system...
so just like a regular helicopter
AFAIK: The way to make an emergency landing with a helicopter is to make the blades spin as fast as possible during free fall and then use the inertia to create some lift just before touchdown. In theory that is... :scared:
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Kilrah on July 18, 2016, 05:24:02 pm
so just like a regular helicopter
Well except for the energy a heli can store in the rotor and as speed, and the fact that the heli is made of overengineered, heavily tested and certified components that are very unlikely to fail in the first place, not of hobby 2-stroke motors that pretty much have low reliability by design...
Title: Re: Crazy 'Manned Multicopter' must see
Post by: rx8pilot on July 18, 2016, 05:51:36 pm
While I am far from an expert, but it would seem vastly more stable if the center of lift was above the center of gravity. Also, the rectangular arrangement seems to be a unnecessary stability challenge as well. With all that noted, I would at least consider a helmet and other gear to minimize the blood bath when an engine fails and it tips over. Maybe a quick death is better than grave injury?

I will pass over the the word 'genius' for this guy. He does, however, get an A for the excitement part.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: electr_peter on July 18, 2016, 06:15:47 pm
Helicopters can perform autorotation maneuver (i.e. forcing a negative blade pitch to speed up rotor, slowly coming down, then changin to positive pitch near ground and safely touching down), if it has enough height and/or speed and a pilot with necessary skills to do that. It is not a especially hard maneuver for a helicopter pilot. But it may require to change pants afterwards...
Medium to big RC helicopters can also perform autorotation (in addition to flying upside down).

Pilot used so called "single stick" controller (old school type). I am really interested how motors are controlled - I will have look a this video deeper.

Aircraft in video seems dangerous for various reasons. I am most concerned with high centre of mass and potential of single engine failure - it would probably not be able to adjust for 1 failed engine and crash. Limited lifting power is very apparent, it flies just barely.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: LaserSteve on July 18, 2016, 06:32:43 pm
Kudos to the Chinese Guy for building a working Heli, AND teaching himself how to fly it.  However, He's too close to re-discovering the usually fatal "Mast Bumping"  design defect that is present in early  Teetering Hinge  rotor heads.  Mast bumping is avoided by careful flight training, some modern machines still have it as a "feature".   The fact that he got the hinges, rotor balance,  and CG nearly right amazes me. I was really worried until he flew the loop out of the pad area and kept the fuselage at the proper angle.

As for the guy with the "Dead Sled",  I've no comment, other then the structure  ensures his body will probably be somewhat  presentable at the funeral.   Holy marginal dynamic stability, Batman!

"God looks after Fools, Little Children, and ships named Enterprise!"

Steve

Title: Re: Crazy 'Manned Multicopter' must see
Post by: Alex Eisenhut on July 18, 2016, 06:44:44 pm
The thing looks precarious.  Intuitively, I'd have put the 4 center motors further out and blowing out at a slight angle to get a dihedral. The motors look powerful enough to me; they look like two cylinder two-stroke gas engines. I think, I didn't listen I just watched the coolness! I'd suppose the choice of prop is at least as important as the size of the motors?
Title: Re: Crazy 'Manned Multicopter' must see
Post by: ez24 on July 18, 2016, 07:09:41 pm
From a link in the video  (warning sad ending)

https://www.youtube.com/watch?v=9kKm3_YCHf4 (https://www.youtube.com/watch?v=9kKm3_YCHf4)

All these years I thought it was a 737.  FYI  I would never fly Alaska Airlines
Title: Re: Crazy 'Manned Multicopter' must see
Post by: XOIIO on July 18, 2016, 08:00:12 pm
This is the exact sort of thing I'd do, if I was rich :/

Crazy or not it would be awesome.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: langwadt on July 18, 2016, 08:14:00 pm
The thing looks precarious.  Intuitively, I'd have put the 4 center motors further out and blowing out at a slight angle to get a dihedral. The motors look powerful enough to me; they look like two cylinder two-stroke gas engines. I think, I didn't listen I just watched the coolness! I'd suppose the choice of prop is at least as important as the size of the motors?

the prop has to match the torque/speed curve of the motor, the pitch,size etc. is basically the equivalent of a gearbox
Title: Re: Crazy 'Manned Multicopter' must see
Post by: zapta on July 18, 2016, 08:26:09 pm
the prop has to match the torque/speed curve of the motor, the pitch,size etc. is basically the equivalent of a gearbox

Or impedance matching, like a transformer.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Kilrah on July 18, 2016, 08:39:06 pm
This is the exact sort of thing I'd do, if I was rich :/
That's a thing that with my experience I could build and fly within a week - but wouldn't do even if I don't value my own life that much. Or just fly above the water like many others have done before him, but then the interest is limited precisely because it's been done to death already.
While it certainly gets you media attention and $ where's the fun in that.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: ez24 on July 18, 2016, 09:15:24 pm
How does he steer it ?

To me it looked like the shafts that hold the inner motors moves?

Could it be the RPM change in the motors?
Title: Re: Crazy 'Manned Multicopter' must see
Post by: Kilrah on July 18, 2016, 09:22:30 pm
Only RPM difference.

That's usually done using electric motors that respond to commands from the flight controller in a split second, using straight gas engines with their slow and somewhat unpredictable response is already stretching it.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: System Error Message on July 18, 2016, 10:02:41 pm
well at least it beats being stuck in traffic jams and having to pay for parking.
Title: Re: Crazy 'Manned Multicopter' must see
Post by: janoc on July 18, 2016, 10:13:28 pm
Basically he's invented a flying coffin, he just needs to add the lid.

 Yes, who the hell does he think he is, one of the Wright brothers.  :box:

You mean Wright brothers who literally didn't know squat about control issues or aerodynamics at the time, so they were risking life discovering new territory. That vs a guy who takes  RC model gear, everything basically off-the-shelf and builds a contraption to get killed in despite the knowledge about the serious safety shortcomings of this kind of design being widely available?   :palm:

The Wrights were explorers but this guy is just a plainly stupid Darwin award candidate, nothing more. And even if he manages to make the thing fly he didn't invent anything new there - the Moeller's "volantor" or "Skycar" predates this by at least a decade if not more and that actually had at least some safety features.

Volantor
https://en.wikipedia.org/wiki/Moller_M200G_Volantor

The Skycar is actually more a tiltrotor than a multicopter.
https://en.wikipedia.org/wiki/Moller_M400_Skycar

Both were a failure and an abysmal money sink - mainly because of control issues and the safety problems in case of an multi engine failure, solving of which would make it completely unprofitable.

Btw, both Moeller's contraptions could handle single engine failure due to engine redundancy - unlike an X-shaped quadcopter which will immediately flip over if one motor conks out.

Edit: Actually the guy's contraption is an octocopter, not an X-shaped quad, but the engines are so weak that it barely hovers in ground effect. If one of the engines dies, he is going to have a really bad day ...


Title: Re: Crazy 'Manned Multicopter' must see
Post by: StillTrying on July 18, 2016, 11:41:40 pm
I'm not convinced this thing lifts off with him sitting on it.

electric versions
http://www.makermasters.com/e-volo-multicopter-paves-the-way-in-manned-diy-electric-flight (http://www.makermasters.com/e-volo-multicopter-paves-the-way-in-manned-diy-electric-flight)
https://www.engadget.com/2016/04/10/18-rotor-electric-helicopter-in-manned-flight (https://www.engadget.com/2016/04/10/18-rotor-electric-helicopter-in-manned-flight)


Eight 8 HP motors and 10,000 rpm looks like getting close to liftoff.
http://adamone.rchomepage.com/calc_thrust.htm (http://adamone.rchomepage.com/calc_thrust.htm)
Title: Re: Crazy 'Manned Multicopter' must see
Post by: sleemanj on July 19, 2016, 01:04:39 am
I'm not convinced this thing lifts off with him sitting on it.


He has been working on this project for more than a year, here are the videos in order...

https://www.youtube.com/watch?v=DDfaDjChm2M (https://www.youtube.com/watch?v=DDfaDjChm2M)
https://www.youtube.com/watch?v=GBmDlw6xOno (https://www.youtube.com/watch?v=GBmDlw6xOno)
https://www.youtube.com/watch?v=LS_9QaEtELE (https://www.youtube.com/watch?v=LS_9QaEtELE)
https://www.youtube.com/watch?v=2FSJzNmfhRk (https://www.youtube.com/watch?v=2FSJzNmfhRk)
https://www.youtube.com/watch?v=M92QJGYJpl0 (https://www.youtube.com/watch?v=M92QJGYJpl0)
https://www.youtube.com/watch?v=uL9jT_0XcKU (https://www.youtube.com/watch?v=uL9jT_0XcKU)
https://www.youtube.com/watch?v=8lx_fGO31kY (https://www.youtube.com/watch?v=8lx_fGO31kY)
https://www.youtube.com/watch?v=1S0y2fF4Ltk (https://www.youtube.com/watch?v=1S0y2fF4Ltk)
https://www.youtube.com/watch?v=iqN2DqKyKtw (https://www.youtube.com/watch?v=iqN2DqKyKtw)
https://www.youtube.com/watch?v=tthJ0gRehXQ (https://www.youtube.com/watch?v=tthJ0gRehXQ)
https://www.youtube.com/watch?v=a-2i5TkakaE (https://www.youtube.com/watch?v=a-2i5TkakaE)
https://www.youtube.com/watch?v=ALYECvs06XI (https://www.youtube.com/watch?v=ALYECvs06XI)



Title: Re: Crazy 'Manned Multicopter' must see
Post by: boffin on July 19, 2016, 01:31:02 am
From a link in the video  (warning sad ending)

https://www.youtube.com/watch?v=9kKm3_YCHf4 (https://www.youtube.com/watch?v=9kKm3_YCHf4)

All these years I thought it was a 737.  FYI  I would never fly Alaska Airlines

Alaska is my preferred airline living in the PNW.  Their safety record overall is quite excellent, especially given they fly into some of the toughest airports in some of the worst weather in North America.

All airlines have had serious accidents, just some have been lucky enough that everyone walked away.  People are always quick to blame airlines, but aviation safety is a delicate balance between costs (and not overengineering) and safety.  Are there some airlines I'd avoid; sure; most of the regionals are way dodgier than any of the mainlines; and knowing the pilot on my short hop flight likely makes just over minimum wage isn't the nicest of feelings.

there's a superb documentary on PBS Frontline called "Flying Cheap" if you want to know how the airline industry really works.