Multicopters versus the Wind ?

CopterCam

CopterCam

Member
Is it just Western Europe, but there seems to be an extraordinary amount of wind of late. Very frustrating trying to schedule fly time around the vagaries of the elements.

It is a held belief that MRC's will be grounded due to wind when the Heli guys can fly. As regards AP, it is doable given the right platform, camera mount and light but AV is another matter as regards shooting usable footage.

I am considering a heavy lifter..... So, what is a Fly wind and what can we do in the build process to increase the chances of flying in wind ? Are we largely restricted by the limitations of fixed pitch and must we concede that Helis are a better choice in wind ?

Sid
 

Droider

Droider

Drone Enthusiast
What wind speed you looking at Sid.

I am slowly building my confidence in wind. I have shot video in 10/12mph winds not problem. I would rather fly a MR than a heli but I suppose if you are good with a heli you would rather fly that than a MR!
 

B

baker55

Member
As long as you are careful, I have been up in 30k winds about 18mph. much easier doing stills than video at that speed though. Shaun
 

CopterCam

CopterCam

Member
There was a small craft warning in place for today, The Met were forecasting 35Km gusts. it was ok untill I got above the tree line. My AUW with a GoPro HD and 5000mah is 1.8k

Is it likely that a heavier platform will handle these sort of winds better or is it a case of the bigger rig catching more wind and gyros working overtime to keep stability?

If I go with PH how much roll is exerted on the camera mount at these winds? Is there an optimum frame size with regard to motor span ?

Sid
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
Sid,
My experience with the wind so far has been up to about 20 mph which is roughly 17 knots. I've got the GPS gain on a slider switch on the radio which allows me to turn up the gain in higher winds. Higher winds mean more maneuvering in PH so shorter battery life. Crank up the gain and watch the little bugger fight to hold its ground, pretty neat.
Regarding your first comment about the wind, I'm on the East Coast of the US and it does seem to be a windy Spring this year.
Bart
 

B

Buzzed

Member
I had a bad experience with gusts to 25 MPH. Got hit on a steep turn and the Hexa crashed right at my feet. The good news was I didn't have to walk far to pick up the pieces.
 

Droider

Droider

Drone Enthusiast
Buzzed did you DUCK...;)

Bart can you explain the GPS gain slider thingy.. may be a pic or two of how it is set up in MKtools.. I have a spare slider and channel I could use to do this.

Dave
 

J

jes1111

Active Member
Multirotors are deliberately built as light as possible to extend the flight time. But the No.1 weapon against wind is MASS! The wind bears on the available surface area of the craft and displaces it. The electronics senses the displacement and tips the craft in order to come back to the original position. Furthermore, if your camera is slung under the centre of the craft, wind bearing on it creates a fulcrum effect, resulting in attitude displacement as well as translational displacement. Ergo the potential "wind stability" of any particular craft is a function of its mass, it's surface area and the distribution thereof. Electronics and control algorithms aside, more mass, less surface area and keeping the camera closer to the CG point should result in a more "stable" craft.
 

Droider

Droider

Drone Enthusiast
Hi Jes1111.. Welcome to MRF's and thanks for your take on this. So would you say a 4 rotor would be more stable in the wind than say an 8 rotor? I am thinking props create lift for sure but with wind hitting more surface area of more props then this has to have more affect on the craft than the 4 prop version.. I went for a Y6 to try and reduce the wind affect because the places I want to fly.. like in the mountains are more suspect to wind and turbulence. I can also pack a Y6 easier than an Hexa or an Octo!

Droider
 

J

jes1111

Active Member
Couldn't say for sure on that one. But an octo is probably going to weigh more than an equivalent quad - and IMO that's going to have more of an effect on potential stability. I've heard lots of people saying that Y6 craft are wind-tolerant. There are so many variables it would be hard to quantify.
 

Droider

Droider

Drone Enthusiast
I am slowly building up the skills to fly it in stronger winds and will post some video of it when I get a good day that is not to gusty.

Dave
 

B

Buzzed

Member
Droider said:
Buzzed did you DUCK...;)

Bart can you explain the GPS gain slider thingy.. may be a pic or two of how it is set up in MKtools.. I have a spare slider and channel I could use to do this.

Dave
Click to expand...

Dave I actually backed up and then ducked.

Things I have learned: When the MK is perpendicular to the ground there is no lift, it's coming down fast.
 

CopterCam

CopterCam

Member
jes1111 said:
Multirotors are deliberately built as light as possible to extend the flight time. But the No.1 weapon against wind is MASS! The wind bears on the available surface area of the craft and displaces it. The electronics senses the displacement and tips the craft in order to come back to the original position. Furthermore, if your camera is slung under the centre of the craft, wind bearing on it creates a fulcrum effect, resulting in attitude displacement as well as translational displacement. Ergo the potential "wind stability" of any particular craft is a function of its mass, it's surface area and the distribution thereof. Electronics and control algorithms aside, more mass, less surface area and keeping the camera closer to the CG point should result in a more "stable" craft.
Click to expand...

jes1111,

Thanks for your informative reply,.............given that we need battery power, is using a bigger battery an efficient way of increasing mass ? Is there a point when greater mass compromises the handling ? It seems that we need to be looking at a more aerodynamic profile to the design and some way of placing the camera in its optimum position although we are restricted largely if we are to avoid prop/motor intrusion ?

Sid
 

J

jes1111

Active Member
First, remember the 80/20 rule is in play here: the last 20% of improvement is going to cost you 80% of your time and budget :)

Simply swapping a 4Ah pack for a 5Ah is obviously not going to have a significant effect on overall stability. To realise the "benefit" of high mass we have to really go for it! Five kilos (11lbs) plus... that'll do the job. I'm designing my own craft to be just under 7 kilos (15.4lbs) take-off weight (since that's the threshold for operator licensing in many European countries).

Build the craft as light and "compact" as possible so that the majority of its take-off weight is battery. Of course, there's a law of diminishing returns: more battery weight means bigger engines which means more battery consumption - careful calculations needed. Flight time won't increase very much, since most of the battery power will be used to carry the batteries around, but that's okay.

The flip-side to camera stabilisation is, of course, the issue of the camera's own weight. A light camera is more difficult to stabilise than a heavy one. Consider strapping one or more of your battery packs to the camera mount to increase the mass that you're trying to isolate.

Re: camera position - it is actually possible to avoid hanging the camera under the frame, on both a Y6 and an X4/X8 - you just have to fiddle with the layout a bit. You may not be able to mount the flight electronics dead on the CoG point, but most systems are remarkably tolerant of that.

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CopterCam

CopterCam

Member
Most interesting !.................plenty of food for thought. I like the look of the Y6 config. The camera placement exploiting the 120* arm angle looks right. Is there a major benefit in placing the camera close to the prop plane ?

Really like your design, 7kg auw, what camera are you intending to lift ? How advanced is your project in build terms ? Is a maiden anytime soon..............?

Sid
 

J

jes1111

Active Member
The secret with my Y6 design is that the angle between the two front arms is not actually 120 degrees - it's 97 degrees (IIRC) on the image I posted but the latest design has changed that to 85 degrees. So why have a Y6 with the same/similar angles as an X8, you ask? Because 6 engines is enough :)

The major benefits of the layout are that the camera is not underslung (viz. the stability issue), the side-facing surface area presented to the wind is minimised and the craft will be more responsive (ergo more stable) by virtue of the vertical CG being coincident with the propeller plane.

Biggest camera I intend to lift is Canon EOS1Ds with 14mm f/2.8 lens - about 2.4kg. I'll be able to carry approximately 15Ah of battery power for a total weight just under the 7kg mark.

My build is being timed to coincide with the availability of OpenPilot (soon now), so I expect maiden flight in about 8 weeks.
 


Droider

Droider

Drone Enthusiast
Jes

Thats some pretty informative info there. Like your design, how you going to go on about the Arrobot patent?

I'm designing my own craft to be just under 7 kilos (15.4lbs) take-off weight (since that's the threshold for operator licensing in many European countries).
Click to expand...
I have being trying to look into this but I cant make head nor tail of it all. Do we need a licence in the UK for data gathering?. Should we have a licence to prove professionalism for insurance purposes ?
I would be interested in your thoughts on this. I was going to post a new thread on this subject.. mm think it would be a good thread.

Thanks for you input here it is very thought provoking and I guess thats whats great about this site. "Open source" :cool::)
 


CopterCam

CopterCam

Member
jes1111 said:
Forgot to mention one thing: if you're going to carry lots of battery, you might as well make it 5S or even 6S, with the attendant benefits in efficiency of higher voltage (lower current).

http://www.caa.co.uk/docs/33/CAP722.PDF
Click to expand...

Excellent info............thanks for your posts. We bow to your superior knowledge and wisdom, looking forward to your new platform and maiden flight.

It has me rethinking my whole approach an AV rig. Now.............. what insights can you give on a camera mount and its stabilization ?

Sid.
 

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