You will. But not with an Okto or a Hexa.
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30 Min flight time whit fully packed octo
- Thread starter Sebas600
- Start date
MombasaFlash
Heli's & Tele's bloke
When this MRC experiment started with the bog standard MK Octo - the old one with the Y arms - I was just finishing up a day's photography when a propeller blade broke mid-air. Don't know why. Could have been a flying beetle or just a crappy prop. Anyway, the Octo did a little shiver and then carried on as before. THAT sold me on 8 rotor redundancy and I stuck with the flat 8 configuration with the bigger DW AD-8.
Bartman
Welcome to MultiRotorForums.com!!
shhh! things don't break!
Bartman
Welcome to MultiRotorForums.com!!
Bartman
Welcome to MultiRotorForums.com!!
blah blah blah
engineers have been telling pilots for a hundred years now about the safety of their designs but there continue to be lots of dead pilots (and passengers regrettably). shall we go through each failure individually or is it enough to say that individual component design isn't the end-all be-all of reliability. How about we start with the DeHavilland Comet, that should be familiar for you.
ZAxis
Member
Why is it always the Comet example that trotted on occasions like this ... lets not forget the Lockheed Electra and its troubles. Look them up, a bit more relevant to multirotors and our eternal vibration problems.
Of course both went on to relatively successful careers and the last Comet derivative, the Nimrod, has only just been thrown on the scrap heap by HM government.
The Electra still flys as anyone watching 'Ice Pilots' on Discovery will know.
andy
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Interesting that you should be telling me that. But I am not sure what the relevance is to this thread. After almost 13,000 hours flying full size aircraft I think I can say that I am aware of the risk scenario. I know of at least 20 other pilots who died over the last 30 years working at low level. I am one of the lucky ones but luck alone is not the entire reason that I am still here to talk about it. Being a qualified aircraft engineer does reduce the risk to a degree. I have seen people cut into two pieces by rotor blades whilst the aircraft was still at 1500 feet. Most of the bad accidents were because of poor maintenance and unauthorized modifications carried out by people who were not supposed to even touch the aircraft. Just imagine the carnage if full size aircraft were allowed to take to the air with the blind leading the blind approach that many modelers use when building a custom airframe. Fortunately we can have some fun without killing ourselves.
As I recall, the Comet failures were that of a component - The rear windows had stress raising square corners.
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Bartman
Welcome to MultiRotorForums.com!!
the Comet is a convenient example, that's all. there are plenty of other examples, not all aircraft, but bridges, cars, buildings, medicines, etc. where engineers' overconfidence put people at risk. everyone's got to take responsibility for their decisions in the end but we're mostly dealing with consumer grade electronics and mechanical components and I can't see trying to optimize efficiency while ignoring the risks of component failures.
Macsgrafs
Active Member
Good post Bart with the octo in the jungle, i was going to post one of some guy in his back yard had a prop splinter into hundreds of bits, it wobbled breifly but he went on to fly it about as though the motor was still flying...thats why I chose an octo over any other MR.
Ross
Ross
MombasaFlash
Heli's & Tele's bloke
30-40 minutes ... 2-3kg ... HD ... engineers ... dead pilots ... stress raising square corners ... can't remember what this thread was about.
Just to put things into perspective, I just came in from flying my DJI F450 for 28 minutes and 9 seconds before low voltage monitoring forced a landing. That's a small quad with fairly efficient motors, takeoff weight of 1653 grams, carrying a pair of 3S 5000 35C packs. With just one pack I was able to fly it 19 minutes and 51 seconds, adding a second identical pack in parallel increased flight time by less than 50%, similar to results I've seen with several of the other multirotors I have on hand. Adding yet more packs results in ever smaller increases until at some point there will be zero gain and by then you'll be lucky to get more than a couple feet off the ground.
So if anyone tells you they can make an octo that weighs 15 pounds or so at takeoff fly for 30 minutes, they're full of S**t, not going to happen if a small quad at a bit over 3 pounds can't make it to 30 minutes. I just checked the weight and the quad weighs 809 grams and the two batteries 844 grams so in this case the power supply weighed as much as the craft it was powering. The heavier the craft is the more power it takes to fly it, not mention you can double the consumption with 8 motors vs. 4, we won't even go into the difference in power usage between small 905 kv motors on the quad vs what a heavy lift octo would need.
Ken
So if anyone tells you they can make an octo that weighs 15 pounds or so at takeoff fly for 30 minutes, they're full of S**t, not going to happen if a small quad at a bit over 3 pounds can't make it to 30 minutes. I just checked the weight and the quad weighs 809 grams and the two batteries 844 grams so in this case the power supply weighed as much as the craft it was powering. The heavier the craft is the more power it takes to fly it, not mention you can double the consumption with 8 motors vs. 4, we won't even go into the difference in power usage between small 905 kv motors on the quad vs what a heavy lift octo would need.
Ken
MombasaFlash
Heli's & Tele's bloke
What are these 'eternal vibration problems'? Seems to me that some of the complaints around here can get a bit wet. Taking the rotary wing category as a whole these multi-rotors are smooooooooth. Have you ever messed with single rotor nitro or gas helicopters? MR's might have their own special set of issues but I find it difficult to include vibration.
My sentiments precisely.
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ZAxis
Member
MombasaFlash...
Perhaps its just me but I have yet to see an MR vibration free over the whole flight envelope. Most of the good stable video is shot from a slow moving MR and I have yet to see good video consistently from an MR moving in a more dynamic flight pattern. Fast forward flight, fast ascent, descent etc. Our main application is videoing extreme sports so need to operate at these extremes. Our pretty standard MK Hexa2 is a good video platform when treated gently but accelerate faster in any direction and you always hit a period of frame vibration. Its worst in a rapid descent. I have always put it down to inevitable resonances due to having multiple motors and some flexibility in the frame and arms. Our early problems were solved by changing to stiffer MK supplied props and taking more care to balance them but we still suffer at the extremes. I'd love to know if we are unique and no one else suffers in this way.
andy
Perhaps its just me but I have yet to see an MR vibration free over the whole flight envelope. Most of the good stable video is shot from a slow moving MR and I have yet to see good video consistently from an MR moving in a more dynamic flight pattern. Fast forward flight, fast ascent, descent etc. Our main application is videoing extreme sports so need to operate at these extremes. Our pretty standard MK Hexa2 is a good video platform when treated gently but accelerate faster in any direction and you always hit a period of frame vibration. Its worst in a rapid descent. I have always put it down to inevitable resonances due to having multiple motors and some flexibility in the frame and arms. Our early problems were solved by changing to stiffer MK supplied props and taking more care to balance them but we still suffer at the extremes. I'd love to know if we are unique and no one else suffers in this way.
andy
MK Hexa V1, standard MK Hisight II mount, GoPro held on mount with rubber bands. Considering it was windy and how I was flying it I'd say this is pretty stable video and the flight is anything but slow...
It could be made a lot steadier than this and still flown the same way, it's all in the setup.
Ken
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Well done Ken. That is convincing enough for me. You could have made it past 30 mins. with 4 cell batteries.
As for the broken props. That should never happen if you buy the right ones.
Without the additional weight of an I2c isolator your MK Okto will die if a motor or ESC stops working.
With one 5800 4 cell pack and a Panasonic TW-HDC900 camera I was able to fly for about 20 mins. with my F450. (Special motors and Props.)
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MombasaFlash
Heli's & Tele's bloke
Without any clear indicators as to which posts those comments are directed towards I am going to take it as mine.
The MK Octo was a 'toe-in-the-water' to see what these ugly insects ... ooops, mustn't offend the sensitive ... Multi-Rotor Copters are all about. MikroKopter was the only outfit I had ever heard of and so I went for their smallest 'heavy-lifter' and bought the Octo. Of course very soon afterwards I discovered that they had introduced the Octo2 to eliminate the wobbly 'Y' arms. Anyway, I bought the 'kit' in order to have everything required to build it, rather than try and figure out individual components for something I knew absolutely nothing about, and included in that kit were a bunch of props. So I used them. One of them broke a single blade in flight but the Octo stayed up.
At some point during building the Octo I found this forum and started finding out loads more about MR's in general and MikroKopter in particular. I came across posts talking about 'redundancy'. I had never heard the expression in this context but the breaking prop incident perfectly illustrated the principle. But then there were other scare stories about the i2C circuit and how all the motors in the world would not keep the thing airborne if THAT went down. So, as the plan had always been to get a bigger one if the first Octo worked, I stuck with a flat-8 and bought a DW AD-8 HLE, having seen the inherent mechanical redundancy benefits, and also got the i2C isolator board for 'double cover' electronic redundancy protection.
This forum has been a mine of really useful information from people who have been there, done it and then unselfishly shared their accumulated experience on the forum. Naturally there is also a fair helping of chaff and 'opinions', largely guesswork and supposition, and as always there are the know-it-all's. Insufferable self-appointed experts who might well have invaluable experience and knowledge to impart but just have an aggravating manner and a grating way of expressing themselves.
Yes of course, the rich tapestry.
Nothing that personal my friend I was referring to the Jungle clip and the reason why it kept flying. Why so aggressive. Heres something to compare with. http://www.cam-and-carrier.com/file...ad-copter/Quad Copter Flyer rev1_02 Black.pdf
Note the duration! Think of something nice to say about it. It does work quite well.
Note the duration! Think of something nice to say about it. It does work quite well.
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Droider
Drone Enthusiast
This is starting to slightly HiJack MF's thread but...
@ Zaxis.. your MK frame is probably the problem.. far to fexible when you load it up with your Nex5.
Kens vid is very good and shows what you can achieve. BUT for the flying you and I want our fliers for then I think the WKM is a far superior FC. I have been working on a shoot that I could have never have done with the MK. The WKM on my 450 Frame is the perfect tool for fast chase footage where camera stabilisation and perfectly level camera orientation actually deafeats the object.. I posted a vid somewhere with my WKM throwing it around with out a single bit of Jello with the GP hard mounted.. oh and 12/15 mins flight time..
Dave
Bowley
Member
Ken, Now having a little experience of camera mounts (I have the new XA 2X mount) I have to say that is impressive.
What servos do you use on that Hi Sight? Do you think its the servos that give you such precise response or the controller?
Steve
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Bartman
Welcome to MultiRotorForums.com!!
this is becoming a more persistent problem by the day. i'll be bringing it up with the moderators after the Christmas holiday passes.
all the experience in the world is useless if you can't discuss things without being offended every time someone doesn't take your word as law. i find it boring at this point and bothersome each morning when i check in to see what is happening.