Time for me to step up a gear in electric flight

[Adrian Smith 1]

**LINK**

I decided to buy this baby to make the next step up in electric flight into the 78” wingspan league after cutting my teeth on the Sebart Mythos 50E and Extreme Flight MXS 64” leccys. As electric flight is still very much my second string to my first string petrols, I wanted to do this on a budget. I would have loved to liberate an Extreme Flight 78” er, but my available outlay was not up to it so I paid around £200 less for the Winner Model airframe that is distributed here by Bondaero UK.

[Adrian Smith 1]

Right from the start it was clear talking to Chris at Bondaero that there was no manual provided although he said the CoG is located on the main spar, but can be moved 25mm either way without stress apparently. I decided to go with the recommended power train of Dualsky motor, ZTW 120amp Opto speed controller. I purchased separately from 4-Max 20A UBEC to wire into the set up and a wood JXF prop 20x10E size. I will be using 12S power by wiring to 6S lipos in series to do this.

[Adrian Smith 1]

I shall go into quite a bit of detail in this build purely because apart from a couple of flying YouTube clips there is absolutely nothing about the plane (other than the spec.) on any forum I could find that explains pitfalls, endpoint settings for the working surfaces.

So here we go. The kit is well packed and comes in a sturdy carton, although myself and Chris met halfway between ourselves at Cambridge M11 services to avoid the vagaries and cost of ParcelForce. The orange covering and paint finish is to a good standard and bright enough too.

[Adrian Smith 1]

One thing I was less pleased with was, as can be seen in the photo, the ill fitting canopy/battery cover and also the gap where it abuts the cowl. Only cosmetic but nevertheless should be mentioned. A nice touch, however, is the carbon fibre rod into the motor mount that gives the who thing strength.

 

First job was the fit the Dualsky motor. Screws, mount and prop driver are supplied with the motor. After some careful measuring I needed some motor standoffs of about 18mm in length to provide enough prop driver to exit the cowl. The standoffs I found a mix of bits in my spares box.

Edited By Adrian Smith 1 on 09/07/2017 19:22:57

Edited By Adrian Smith 1 on 09/07/2017 19:27:07

[Adrian Smith 1]

All screws, bolts, bolts and nuts were Thread locked for safety of course, as was the airframe cyanoed along the joints just in case of weakness.

I will try and do a bit more on the project this week if I am not flying.

[Denis Watkins]

I often buy 60 - 70mm standoffs Adrian, in fact any long lengths of tube etc, and I cut them down and face them off.

This way, every size is always in my stock box

[Adrian Smith 1]

Good idea Denis. Because of using various lengths on my petrol engines I had the right length combination to spare. I notice that 4-Max sells stand offs that can be cut to length with buying the bolts extra.

[Adrian Smith 1]

Well, I have had one of those near perfect days today. SWMBO was out all day and the early morning weather in my neck of the woods was perfect for some electric flight. So there I was standing in the sunshine at 8.30am in 5mph winds contemplating this is the reason I love this hobby. Four flights later time to have some fun in the workshop. I fitted all the control horns with 30 minute epoxy. I threaded a bolt through each horn pair to ensure all was square while the glue cured.

Nice to observe that the kit comes with some decent Robart hinges for the rudder, elevators and ailerons. I used some Gorilla glue mainly because of its gap filling properties.

Edited By Adrian Smith 1 on 10/07/2017 15:22:50

[Adrian Smith 1]

Now to test fit the servos. On the ailerons, I had to buy a couple of Savox MG digitals that pull 16kg torque at 6 volts ( 12kg or above recommended). The shorter of the push rods are used here and there is still scope to wind them in a fair bit.

For the elevators I already had a couple of spare Hitec 5645 MG digitals which are 12kg at 6 volts so in they went.

As an observation the tailplane CF spar is quite a tight fit so care was required during test fitting. Next job will be to make up some extension leads to the right length for all four of these servos. Something I will do later in the week. Also I am going set up the pull/pull rudder arrangement. Hopefully this is not boring for you folks, but it will get more interesting when I start to fit the internal power train. Additionally, I feel something needs to be put on record for anybody contemplating buying the kit given the dearth of info out in the ether.

Edited By Adrian Smith 1 on 10/07/2017 15:25:15

[Martyn K]

Looks an interesting build and setup.. Following..

[Adrian Smith 1]

Thanks Martyn. As a flier of 60cc petrol models, I just thought I would see what could be done with a biggish electric a/c now I have played around with leccys of 60" or less wingspan. As an ignoramus in most things electrical it will be interesting and challenging to see how a 78" electric aerobat/3D plane and its power train is set up correctly and may be encourage others to go the same route if the desire is there. Thus far the electric journey has been enjoyable, more than I thought I must say.

[Nigel R]

What sort of size petrol would this be (roughly) equivalent to, would you say?

Is there much difference between the two in AUW at this kind of size?

[Adrian Smith 1]

Nigel, it is roughly equivalent to a 30cc petrol. Without battery, weight for this one is 4200-4300g . if add say two 6S 3800 mAh Lipos in series that would add another 1200g making best part of 5500g AUW. For a comparable gasser you are talking 5000-7000g I guess but I will check that. Hope that helps.

[Adrian Smith 1]

Sorry Nigel, make that 7000-8000g for petrol 30cc models checking around, so quite a bit lighter.

[Adrian Smith 1]

Next a bit of crimping. I needed to make two elevator extension leads of 23" in length. Fiddly but needs must. I get all my wire and fittings from the Component-Shop which provides a good mail service.

All finished and the fit is fine and secure.

[Adrian Smith 1]

Next I threaded the leads up the fuselage and taped them to where the RX is going.

Rudder hero installed too ready for the pull\pull wires. In this case it has a torqueof 10kg, but will change for another, better quality  one if not powerful enough.

Edited By Adrian Smith 1 on 11/07/2017 17:24:19

[Adrian Smith 1]

Ok, so next the pull/pull wires. The couplers that fit on the horns are different than the ones that fit on the servo arms. The ones that fit on the servo arms have a bigger bush on them.

Wires double threaded and cyanoed in too.

The wires are threaded through the fuselage by crossing over sides for ease of movement. I have taped the wires to the servo arms as I ran out of time. I will fit the couplers another time.

Edited By Adrian Smith 1 on 11/07/2017 18:07:27

[Nigel R]

Thanks Adrian

Quite a decent weight saving on the electric route by the sound of it.

[Adrian Smith 1]

Yes it is, Nigel. One truism I have found over the years is that no matter how big the aircraft, the lighter it is the better it flies - and more importantly, landing them is such a doddle.

[Gordon Tarling]

Adrian - rather than use the flat wire for servo extensions, the twisted stuff is to be preferred. No need to change what you've already done, but bear it in mind for the future.

[Chris Walby]

Nice build, one issue I have come across on smaller models and would interested in your solution is achieving the correct C of G on models designed for IC, but with lighter electric set up if its tight on space in the cowl?

Edited By Chris Walby on 12/07/2017 12:05:23

[Denis Watkins]

Have done many conversions either way and their is little difference in the weight of IC and electric plus lipo.

As you have found IC is a heavier motor but overall with the lipo they balance out

A trick I use with small models is to fit 2 small lipos in series, as putting one into the bay after the other

Is easier than fitting one large lipo

Edited By Denis Watkins on 12/07/2017 12:34:36

[Adrian Smith 1]

Gordon, I have never had a problem using flat wire for servo extensions which appears to replicate what Futaba uses (as opposed to Hitec which it twisted) so I can't see what the issue is. Feel free to explain.

I had time to wire up the rudder servo pull/pull arrangement. I clipped the rudder so it didn't move and centred to servo to do the job.

All nice and tidy.

[Adrian Smith 1]

Chris, in answer to your question. I have not done any IC/leccy conversions, but what Denis suggests experimenting with different weight Lipos seems the answer. I notice that even similar spec Lipos of different makes have different weight. For instance a 4500 mAh 6S Hacker Topfuel is lighter than some other makes of similar specs by some way. Horses for courses I guess.

[Adrian Smith 1]

Next the tail wheel assembly. What a pain that was.

The grub screws provided with the set were not long enough to grip the tail wheel arm and rudder rod so I had to replace them with a longer M3 screw and thread lock them in. Not pretty but job done. The other thing I had to do was add another collett to stop the up and down travel of the tail wheel arm.