I have done a redundancy test with a Y6:
Motors: MK3638
Board: arducopter
ESC: Plush 30A
Frame: y6 rc-carbon
Lipo: 3S5000
Weight: 2.3kg
I have tried to takeoff with a motor disconnected but the copter was not able to lift and it flipped inmediately.
Is the redundancy of the Y6 only applicable during flight?Maybe the board needs some time to recover from the unstability of the fail?
Any thoughts on this test?
Replies
http://www.rcgroups.com/forums/showthread.php?t=1378824
Happy halloween!
Hi,
I also have a Y6 with a thrust to lift ratio of about 2. When one of the upper propellers is missing, I can still fly almost without problems. But when one of the lower propellers is missing, I crash...
Successful hover with upper prop missing:
http://vimeo.com/20977475 @ 0:33s
And here, I lost one of the lower props, flying seems to be impossible:
https://www.youtube.com/watch?v=7P9tE61GWqI#t=2m03s
I was also a bit surprised, because I never lost a lower prop before...
Did you already try to stop one of the upper motors?
I'm thinking that control loop speed may be a problem... theoritically, what's the speed of the air coming out of the "pipe" for 2 prop's vs. just 1?
I can't reply under your message mike :(
Motor info is here.
MK3638 are Pulso 2814/20 840kv rewound to 22 and not 2814/22 re-badged
Try it with the copter in your hand (is your landinggear strong enough to hold it by the landinggear ?), that will be less destructive if you are carefull with throttle and you'll feel how the copter wants to compensate (or not). Take care not to let the props cut yourself though !
Thanks for the responses.
First, I mean MK3638 motors (2kg of thrust).
For hovering, each motor-pair needs to produce 2.3kg / 3 = 766 gr thrust. Maybe for lift you need a little more... but taking into account the motor is rated at 2kg maximum thrust my thought was one motor per arm would be enough to maintain a hover at least.
I have seen several videos of y6 motor failures without crashing
https://www.youtube.com/watch?v=pjM3sZz5zgE
http://www.rcgroups.com/forums/showthread.php?t=1362884
And some comments (1,2) from seismicwave, a reputated rcgroups user:
I have checked that arducopter 2.X y6 motor source code is identical to multiwii code....
So, my only hypothesis is that there are differences between a fail in the air and a fail while lifting.....
On paper, traditional octo and sometimes hexa (depending on motor/prop hover thrust levels) are good candidates for recovery from a failure; I don't see the same good prospects for Y6, unless you specifically design it into the propulsion, and I do not see an efficient flight design for Y6 to achieve that redundancy... on paper, that is.
The one good motor on the arm of the failed motor needs to be able to handle the load.
The other four good motors are unafected and cannot lift that arm.
Thats a very different problem.
That would be my bet, what % throttle do you hover at? The 5 remaining motors need to have enough power and throttle to cover for the 1 motor out.