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Posted by on Oct 27, 2012 in Blog

AC1 V2 Down for upgrades…

AC1 V2 Down for upgrades…

Is 6 really better than 4 ?

I am beginning to think that ‘upgrading’ to an F550 was a mistake; at least in thinking that I might be able to just sort that out quickly, and it would all be fine. 2 more motors I thought, half the lift again, surely ? No.  More stable flight, because there’s more motors ? No, worse if anything… interesting.

So this week has mainly involved finding problems that need to be solved, and trying to solve them, as opposed to running round the countryside documenting Autumn like I should be. Which is slightly disappointing given that Autumn is looking especially good at the moment, in between all the rain.

No, what I have now is a much heavier and less manoeuverable craft that still won’t easily lift the reasonable payload I want it to, and in the brief moments it does, won’t give me any sort of flight time or enjoyable flying fun because my confidence that the hexacopter is within my control at all times, and rescue-able from steep drops and descents is at an all-time low, which means I can’t take it new places to fly and concentrate on getting great aerial footage because I’m having to spend all my time doing test flights at training grounds and worrying about whether it’s got the power to stay where I put it in the air. This not so much enjoyable as ‘interesting’ flight and doesn’t produce entertaining video, which is why there aren’t any this last week.

Also, and contrary to what I had read I should expect, this craft seems utterly at the mercy of the wind, which catches and drags it far worse than my quad ever did, making usable footage doubly difficult to get. As skating about in wind is essential if you are going to try and fly with any sort of regularity in the UK, it’s going to be a bit rubbish if I can’t do it. So that, and having just been informed that better motors will make no difference unless I also get motor arm extensions, go up to bigger props AND change all my battery packs to 4S, there was opportunity for disheartening that I choose to replace with detached acceptance and the joy of new and fiercely diligent research. I have spent 5 days glued to a chair while I download more of the internet into my brain. In order to make room for this, I have forgotten how to play at least 12 80’s power Ballads on a piano.

What can we do about that ?

So a new plan is required, and this is it.

We will be needing…

6 of these…

6 of these (incl. spares)…

6 of these…

and 18 of these.

8 of these…

1 of these.

 

 

 

 

 

 

 

 

 

 

So, T-Motor 2814/10 770kV motors should add a decent amount of lift authority to proceedings, and 4S batteries means everything is spinning 25% faster and generating more lift, and resisting the wind a lot better. Carbon slow-fly props should do better than the 10″ Graupners in the lift department too. If I add all that and STILL don’t have enough lift for agile wind resistant flight we’ll have to get the 2″ arm extensions that allow me to use 11 x 4.7 carbon props which should give me more lift again. To compensate for rubbish flight times I am going to have to send up 2 parallel 4000 maH power packs which, according to the excellent software ecalc (on which I am checking these things might work) will give me about 10 minutes of hover, and 7-8 mins of normal AP flight.

But is that going to work ?

Here I face a conundrum I cannot immediately resolve. If you are not technically minded, skip this bit. Let’s look at the ecalc calculations for this rig using Tiger Motor 2814/10 and Graupner 10 x 5 E-props (or at least APC electric equivalents).

We’re not getting any warnings here, but some of our readings are uncomfortably near the top of the range, and close to the capacity of the motor.

Let’s try swapping up to Graupner 11 x 4.7’s which should give us a lot more lift… so we enter that into ecalc…

Oh dear – we’re over power for the motor, which could apparently lead to heatings up and burnings out. But this is in opposition to everyone that actually sells Tiger Motors, who all list recommended prop size as being 10 x 5 right up to 12 x 4.5. So I need to find out which is correct, what variables I need to change to bring the readings to much less close to maximum capacity, and then decide if those 2814’s will do it. They are the largest motors that will fit to f550 arms, so if they aren’t going to be enough, I am not sure what else I can do that doesn’t involve getting a new frame that can take bigger motors. There are other motors I have considered, Avroto, Torxpower, iMotor, SunnySky, Axi etc, but it is often difficult to get all the specs needed for ecalc to work out what’s going to happen, and then to make sure I can fit the variety of propellers I want to try to the wildly varying shaft diameters.

I also have to decide if I can make do without the ESC’s – it may be that my current DJI 30A Opto’s will do the job. So, I am currently in the process of deciding what is the right thing to do, making it arrive, and then become part of a newer, shinier heavy-lift hexacopter.

It will be extremely easy to make a very expensive mistake here, so I am taking my time deciding, and won’t order stuff until I am 90% sure this plan is going to work…

We’ll see how that goes. More from me when it happens…