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Time for me to step up a gear in electric flight


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Now looking a bit more like an aircraft with the U/C legs bolted on.

fullsizeoutput_9b1.jpegOnce again not straight forward as I had to put the bolts through downwards (as opposed to upwards) because of accessibility issues. Easier to get a spanner to the nylock nuts on the outside of the fuselage and an Allen key to the bolts heads internally. Not a problem in the final analysis.

It is still easy to see the ill fitting canopy cover at the front on the port side. Urggggg..... still will have put up with it! angry

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Nice to see you doing another build Adrian, I find any build thread helps motivates me with my own builds - I've been collecting parts for the build of your old Edge recently.

Interesting that you make your own cables, I've never had the confidence to do it!

Try not to stress about the canopy, its a nice looking model - even if it is electric wink

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Rich, making my own cables is a relatively recent thing. There was a really great article on crimping in the October 2016 RCME by Tim Kearlsey which set me off. The main thing to have is decent crimping pliers and that makes the whole thing much easier. Need to practice a bit to start with, but it is a skill that is easily accomplished.

Yeah, the old hanger is filling up again! I have a humidity meter in there and whilst it reads a bit on the high side in the winter I find covering everything in clear plastic sheeting seems to protect the models adequately. Glad the build thread helps. I just try to put something on here that there is little or no info on the internet about. Even though I have put together a few planes in my time, this one is still, and will continue, to be a journey of exploration! Particularly as I still have a liking for petrol IC giant scale stuff as opposed to the complexities of electric.

Hope you find all you need for the Edge 540 as I look forward to hearing about the maiden.

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Adrian - it could well be my aviation background creeping in here, but I was taught that twisting cables helped to cancel out radiated 'interference' - what I've read on other forums has also led me to believe that twisting is a good thing to do, particularly on longer runs. Now, I'll be the first to admit that this could all be totally irrelevant now that we're using 2.4gHz systems, but I always use twisted cable for any extensions that I make myself.

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In communications (telephone, networks etc) twisted cables are used to prevent crosstalk which is another name for interference. The theory is that any interference will be equal in all wires and at the receiving end a differentiator circuit is used to only recognise differences in the signals, the common (interfering) signals are ignored. Whether this is the case with servo leads depends on the circuitry used in the servos.

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All very interesting gents and thanks for the explanation.

That said and as long time user of Futaba gear, all the Futaba extension leads I have bought in the past (as opposed to making them) are of the flat wire type. I have regularly used extension leads of up to 2' for some years now and have never encountered a problem. Your comments about 2.4gHz systems could be the answer. I know in the early days of electric flight when I was using 35meg, I was regularly getting glitches. That's when I decided to go back to I/C where no issues were encountered. The other reason the return to I/C  was because the battery technology was nothing like as good as it is now.

Edited By Adrian Smith 1 on 14/07/2017 14:21:20

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  • 2 weeks later...

Now starts the interesting bit.

fullsizeoutput_9d3.jpegThe Opto ESC has a longer signal wire into the RX whilst the shorter one goes to your preferred programming vehicle. There is a thin anti-spark wire which won't be used so that will be insulated off. Two power leads left and on the other side three connections to the motor.

fullsizeoutput_9d4.jpegThe UBEC leads need to be spliced into the power leads somehow. Any clever suggestions as to the easiest way to do it? the signal leads are for the battery and RX battery channel I guess. There is a jumper on the unit to adjust to the preferred voltage. In my case 6 volts.

Edited By Adrian Smith 1 on 22/07/2017 22:57:50

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Rich, the y-lead is to join two 6S lipos together in series to make a 12S set up with the single connector going to the ESC.

Now I have to wind back a bit as I have interpreted something wrong here with the UBEC unit from 4-Max. As I am using a separate RX battery I assume the red and black leads on the LHS of the UBEC are for this. Now on the RHS here are two leads with Fut/JR plugs on. I imagine one of those leads goes into the RX battery socket. Don't know what to do with the other one (or which one is which). Mainly this is because the ESC had a similar lead that goes into the throttle channel (I assume). If I can't work that one out I guess a phone call to George at 4-Max might solve it.

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Well I have just had a "eureka" moment after talking to George at 4-Max about the wiring on the UBEC unit.

fullsizeoutput_9d4.jpegApparently the two wires on the right hand side with the futaba/JR plugs should BOTH be plugged into the RX. One on the battery socket and the other at the other end of the RX circuitry using a y-lead if need be. This is apparently due to the fact that with the voltages involved, to spread the load across the RX so to speak is recommended.

The other interesting fact he relayed to me was that when using Lipos wired in series, the end charge should be near identical or this could also cause problems. So balanced charging at all times is essential. This is all an education for me and I am glad I am taking the time to understand it all.

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Nigel, as I understand it, on my RX, the battery socket is CH8 for instance, so the other UBEC lead would plug into CH1 which has the the aileron connection already. So using a y-lead the aileron and other UBEC lead connections both go into CH1. This spreads the load across the whole RX circuit board. Hope that helps.

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Time to get the powertrain laid out and soldered up. First the ESC end of the equation.

fullsizeoutput_9d9.jpegAnti-spark connection on the LHS of the ESC with an EC5 connector that joins the y-lead connection to the two Lipos. The long Futaba/JR lead goes in to to throttle channel. As it is an Opto ESC, all three wires in the CH3 plug are used as I understand it. Also I am using a separate power source for the RX with a UBEC.

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Next the UBEC wiring.

fullsizeoutput_9da.jpegI have soldered the connection to the RX battery on the LHS of the UBEC wiring in a switch. In this case I am using a 6V eneelop pack. The two leads on the RHS plug into RX - one into CH1 with y-lead for use to connect to the ailerons and the other lead into the battery socket in the RX which will spread the load.

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Funny how first glance after a few hours in the workshop you don't think you have achieved much. Then you realise much has been accomplished. Today was such a day. First, I did a couple of small jobs on the MX2 (yes I know I am putting off connecting the whole thing up for testing). Anyway first to the U/C.

fullsizeoutput_9dc.jpegThat took longer, as I had to add two nuts to each axle to get the spacing right for the wheels not to foul on the spat.

As can be seen I had to add a couple of washers to reduce play of the wheel on the axle too. That done I had to make a plate to fix the RX switch to the fuselage side, as there was no provision for this.

fullsizeoutput_9dd.jpeg

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Now the power train wiring, UBEC wiring an RX plus Lipo y-lead was all laid out roughly where I intend it to be prior to testing.

fullsizeoutput_9de.jpeg

Can't put it off any longer. I set the throttle CH end point (CH3 on Futaba T14SG) on the TX to 140% +/- to make

sure there was enough scope. Connected the RX battery and switched on the RX. Next I connected the Lipos to the y-lead and connected via the anti-spark connector. All well and good, but...........

The ESC started playing its programming tune and it kept on and on and on.......

Everything worked except the throttle/motor. Connected and disconnected a couple of times, but all for nought. Then I had a brainwave enlightenedTry reversing the throttle CH direction! That did the trick. I was able to calibrate the throttle as per the ESC instructions and next I checked the direction of the motor. Wrong sense! So next I reversed two of the wires to the motor from the ESC and all was well. Just about had enough time left to balance the wooden prop 20x10 in this case, using some clear lacquer. That all accomplished I will sort out the CoG and battery positions another time.

Edited By Adrian Smith 1 on 29/07/2017 22:11:01

Edited By Adrian Smith 1 on 29/07/2017 22:11:47

Edited By Adrian Smith 1 on 29/07/2017 22:12:49

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