By Brian Austin

The interest in this model came about, by virtue of a friend who was seeking an electric glider to back up one that I had let him have. That model had given him a taste of soaring, without the attendant, complications of winching or bungying to launch the model. So having done a search on the net of sites offering electric powered gliders, I settled on the Alexi XX one the Ace Models site. The write up on the site gave a good idea of what the model was about, plus there are details of servos that would be suitable for the model. Receivers were not mentioned but more on that later.

Here is a brief description, to give an idea of what it is, without leaping on to your PC, just yet. Wing Span 2540mm, wing area 42.5dm2, airfoil HN345, fuselage length 1350mm & empty weight 1290g. Controls are Motor, Elevator, Rudder, and Ailerons & Flaps. It will take brushless innrunner/outrunner motors up to 35mm diameter, using 7-16 cells Nicad/Ni Mh or 3-6 cells Li Poly.
From the above, it will become apparent that this is a smaller version of F3j type of moulded glider that has become the standard for glider competitions nowadays, both for home & international competitions. Thus it is not a beginner’s model, plus it will require a reasonable experience in assembling this type of model, to get it to the flying stage, but once there, if you have not flown this type of model before, the rewards are very stimulating.

So a phone call to Acemodel, revealed that they were in stock, but the only colours that were available, were white with blue or red tips. I had really wanted yellow, as I find that is a better colour for visibility, particularly as you get older, but white with red tips was the next best option, so that is what we ended up with.

Whilst waiting for the model to arrive, a search for servos to suit was carried out, using the detail supplied on the Acemodel web site. I decided to use Futaba 3150 Digital servos in the wing & Hitec HS85MG, in the fuselage for rudder & elevator. These choices would probably have changed had I seen the model first, reason being (1) cost (2) size, but again I will discuss this in a bit more detail later.

The model arrived a couple of days later, in the hands of Austin Guerrier, the agent, who was in my area, thus saving any possible damage via the mail service.
As any one will tell you, who have purchased this type of model, you do not get any frills such as boxes, full instructions or accessories to help complete the model. What you do get is a beautiful moulded, Carbon/Kevlar fuselage, fin/rudder, wings, tailplane, canopy hatch, wing joiner (a massive 16 X 14mm section in carbon fibre) & a bag containing a mounting plate for the motor in fibreglass board and the covers for the servo openings in the wing & fuselage. There is a sheet supplied that gives details of set up suggestions for controls, CG etc. On top of this you will need a Motor or Motor/gearbox, Speed Controller, Receiver, Rx battery pack, Power battery (I used a Flight Power 2100 Li Po, Brass screw in Horns for the Aileron/Flaps & Rudder (Ace Models can supply them if you specify when ordering), Servo Wire & JR/Futaba Plugs and 4Pin Plugs & Sockets, to make wiring connection to wings.

On surveying the fuselage, to ascertain how the various parts were going to fit in, a brief description of the positioning of the Rx & servo’s might prove of interest. Unlike most of the models using electric power, the Rx & 2 servo’s for the elevator & rudder, are mounted behind the wing in two moulded compartments, Rx on one side (starboard) & servo’s on the opposite side (port) in front of Rx bay. Inside the servo bay are two pre installed servo connecting rods, to the elevator bell crank & to the rudder.  This is very neat & keeps the important pieces of your installation out of harms way, if there is a fast arrival, with Terra Firma, causing the battery to try and exit at the front of the model.

Installation of the Fuselage Servos, Rx, Wing Servo Harness & drive System

The motor mounting plate was drilled to take the 4 x M3 screws to attach the Kontronik Fun 400/42 motor gearbox that I was going to use, as I already had this motor available. The plate was then epoxied into the nose of fuselage. The canopy hatch needed to have a couple of U shaped 20swg wire retainers, epoxied inside back & front, to hold it in place (see photo) Air intake apertures are required to be made in the two moulded areas on the side of the nose.

The two Hitec HS 85 MG servos, were then fitted to the servo bay, after first checking that the servos were set to there neutral position & if using computer radio, checking that the centering of the servos was set to 0%. You should do this to all servos before installing, so as you do not get problems once you have installed the servos & connected them.
Epoxy brass horn into position indicated in rudder. By bending the rudder to the right (starboard) you can apply epoxy inside the rudder, to the horn to secure it firmly, as it is hinged on one side only.

  

There is not enough room to fit a quick link to the rudder horn, as it fouls the fared aperture in the fuselage. So I opted to bend the wire upwards at a right angle that will pass through the said aperture, when the rudder is being activated. Loctite a small piece of Ali tubing onto the wire above the horn to stop the wire from falling out.

 

Solder two quick links to the connecting rods, via the threaded connecting link for attaching the servos, to the push rods. Set elevator bell crank to the mid position, as seen through the slot in the fin and set the rudder to neutral position. After cutting rods to length, to give you enough to solder into quick link connector, solder into the threaded connectors.
You will need to warm up the servo arms with a heat gun and bend them down slightly, to follow the section of the fuselage, where the quick link engages the servo arm, to give free movement without fouling the fuselage sides.

Next make sure the Rx will fit the aperture assigned to it. There will not be many 8 channel Rx’s that will fit the model. I chose to use a Schultz 835, with rear plugs. I have used these on many occasions and found them very reliable, for the price.

Unlike the standard type of F3j gliders that usually employ a one-piece centre section on the wing, the Alexi has a two-piece wing that assembles onto the large wing joiner mentioned previously. Therefore the use of the 9pin plug & socket that is the norm needed a rethink. What was needed was a 4pin plug & socket, for each wing half, so as the two servos in each wing could be connected, on assembly. (You connect 2 reds to one pin, 2 brown or blacks to the next pin & then the signal white wire, from the flap servo to the next pin & finally the aileron signal wire white, to the last pin) Multiplex were the only ones that I know of, who had anything resembling this spec. The only snag is that it is not polarised, so you need to identify one end on each half, so as not to plug them in the wrong way. I should mention that the male half on these plugs does have a small protrusion, so that helps but one on the female half would make it easier. (I have now seen a polarised one that Multiplex market, but it is larger than the ones I used.   Two sets of harness were made up, plugged into the correct outputs on the Rx, after threading them through the side of the fuselage, aft of the wing joiner. I place a small rubber band from each plug, over the fuselage, to stop them from falling inside the fuselage in transport & storage.

Installation of the Wing Servos

The servos chosen for the wings were Futaba3150 Digital servos, but on reflection, I personally do not think that Digital servos are necessary, as unlike F3j gliders being winch launched the strain on the wing servos, is no where near as high. I would suggest that GOOD Quality Metal Geared servos, that are no more than 13mm wide or deep however you  view them & generating about 2.5 Kilos torque, will suffice. Two wiring harnesses will need to be made up, one for each wing, to connect the wing servos to the sockets that exit the fuselage at the wing attachment point. Make an aperture in the root chord of each wing to coincide with the socket exit point. Note: - I always have the female socket on the battery side (fuselage), so as there is no chance of shorting out with exposed pins from the male side of the connectors.

Make up the Multiplex male connectors, making sure the wires match the female half when connected. The living hinges were extremely stiff, when taken down to any where near where they needed to travel to, in the down position. This I felt would be of big problem, on the flaps, that are required to travel down to about 75-80 degrees for the crow braking position. A phone call to Austin revealed that the manufacturer new of this problem and was now correcting this by thinning the material that is used for the hinging. He advised me to place them as far down as I could and tape them in this position, whilst leaving overnight or longer, to stretch the hinge line. I did this, whilst placing some weights on the flaps as they were at right angles to the bottom of the wings, so as to stop the wing skins from distorting as they folded back. This had the effect of pushing the skins down, to minimise the distortion.

The horns need fitting to the flaps & ailerons, in the area that is moulded on top of the surfaces. They are installed following the line of the mouldings, which are set at approximately 30degrees to the top surface towards the leading edge of the wing. I drilled them 2.6mm, then tapped them M3, so as I could screw the horns in & adjust for length if need be. You can of course, drill 3.0 & epoxy in place. The exit apertures where the connecting rods pass through the top of the wing surfaces, for the ailerons & flaps, need removing, leaving a small area either side, for attaching the covers supplied. A lot of work is needed now to get the flaps to work correctly, as the linkage to the horns will foul the flap fairings that seal the gap on the hinge line. This is not unusual with this type of bottom hinge flap driven by a horn on the top surface. The quick links will need to be filed away on the bottom edge, so that the hinge seal does not restrict the movement when full flap is deployed. I even bent a slight curvature, when viewing the side profile of the quick link, to reduce the amount of metal that had to be removed.

To connect to the servo I used an idea that I have used before. Hold the relevant control surface level with the wing (pieces of scrap 1/16 balsa or card folded over the trailing edge & a small Bulldog clip over the inner gap, stops this from moving about whilst fitting this). With the Quick link assembled to the rod & attached to the horn, bend the rod that comes with the quick link, at a right angle, in line with the hole in the output arm, when the servo is in the rough neutral position. Make sure that it will operate without fouling the covers supplied for fitting over the servo apertures. Cut the rod off to leave about 3mm on the servo body side of the servo arm.
I then thread the end with an M3 die & attach a n M3 nut to retain the rod, so as it does not fall out. You could use a piece of aluminium tube as on the rudder connection described previously.
Attach the servos to the wing with servo tape & check that the servos are operating correctly for travel/direction etc. When satisfied, they should be glued into the wing with silicone or Rapid Araldite, after wrapping them in making tape, so as they can be removed if required. Failure to wrap them in the tape will make them all but impossible to remove. Finally fit the covers for the servos, with Diamond Tape, both on the wings and fuselage.

Set up and Flying

A Hi Melody 60amp Speed Controller was used, as I had used them before, being reasonably priced and easy to set up.  As I was using digital servos where the current drain is quite high for the BEC, a separate battery was used for the Rx & servos. This was in the shape of 4 AAA 900mah NiMh cells, made up into a pack. These can be bought from Maplins, to make up into any size pack you like. They are also small enough to get right up into the nose of the model, next to the main power battery. If you are worried that the 900 mah are not enough, you can make up 2 or 3 packs to have with you just in case, as they are cheap enough to make up.
For the main power source I chose a Flight Power 2100-mah 3-cell LiPoly battery, as I had two that I had been using in another model.
All the batteries were installed as far forward as possible, to get the CG in the correct position. Even allowing for that, about 85 grams of weight was needed to get it somewhere near to what was supplied as being where it should be on the set up sheet. The control throws were as indicated by the manufacturer, for initial trial.
The flying all up weight came out 1900 grams, a little on the high side for my liking, but try it and see what happens. I have acquired it to fly in windy weather conditions.
The wings are retained, by taping the wings to the fuselage with insulation tape on the top surface only. I was not to sure about this method, but Austin Gurrier assured me that it was OK. You could use the old method of a hook in each wing half, thence an elastic band connecting them through the fuselage.

Came the big day to try it out, which was rather more windy for test flying than I would have liked, but heck that is what the model is meant for. I ask a fellow club member, Bob Wells, to give me an hand launch to give a rough idea as to the CG position. This proved a bit of a waste of time, as the model did not seem able to achieve flying speed to gauge anything as to the handling, all that resulted was a rapid descent into the ground. Also the coupling of the ailerons & rudder resulted in a very aggressive response to the turning response, more on this later. Another hand launch this time with positive flap, gave a much better glide angle. So onto a power flight, to get a better idea as to what the flight characteristics were going to be. Looking back, this is what I should have done from the start, as you seldom test glide F3j models now, again as the speed from a hand launch seldom corresponds to the models true flight speed, but old habits die hard,
Bob launched the model again for me, as the wind was really very gusty, certainly in the region of 16mph plus. Model climbed away no problem at all & after getting up to approx 4-500 feet, the throttle was cut to see what the handling & glide was like. The handling was still a bit twitchy, so took out the combi switch that decouples the ailerons & rudder, which made the handling a lot better. There was a marked change in the trim, when changing from positive flap, to neutral flap & finally to negative flap setting. Positive flap, gave a good glide angle, neutral flap resulted in a real nose down attitude which needed some up elevator trim to compensate, whilst the negative flap, although there was some change was not as marked as going from positive to neutral. It did of course prove to be too much elevator when in positive flap mode.  The elevator also proved to be very sluggish in response to my stick movement, which indicated the CG was to far forward. So time to land, reflect & adjust. The landing was tricky, as the setting on the crow braking needed more down elevator, as the model reared up like a startled stallion, with full crow braking.

On landing, I reduced the weight in the nose to 26 grams, to get more response to the elevator & in an effort to reduce the amount of trim change in the flap settings, then finally doubled the elevator setting for crow braking, from what was given in the set up sheet supplied.
Although the weather had not improved, decided to have one more attempt before the light faded early, as this was late November. Result was much better, but the model was still a bit twitchy in the lateral axis, the elevator was a lot more responsive, but the trim changes were still apparent & the amount of elevator trim in neutral flight did, I feel, add to much drag by forcing the model to fly at the wrong angle of attack.

So on landing packed up, to retire home for some reflection, as what to do to improve the models set up, as it did show a lot of promise.
It suddenly dawned on me, whilst mulling over the afternoon flying session that the combi set up, was too fierce in regard to the rudder/aileron set up, as to the amount of rudder input to aileron, this was cut back to give much less rudder. I had been there before with this problem, in a scale model that I built last year & when flying a friends scale model some time before that, in that when the ailerons & rudder are coupled, particularly on models that have a conventional cross tail, the rudder is much more effective, when coupled than it is on V tailed gliders.

As I can have a set up on the Multiplex 3030, that can give me three different flight settings, whilst in flight, by flicking the Memory Change switch, I used this to change the ailerons/flaps settings, for normal flight. This amounted to reducing the throws quite dramatically, to try and smooth out the turning of the model, in a thermal type flight mode, but you still retain plenty of control in the other two setting, if it does not work out right. While I am on the Memory Change switch it might be of interest to some, that I use a set up that is not often used by some flyers, but I find for competition flying invaluable. In the UP position, the motor or throttle is on the right hand stick (mode1 in my case), for the motor run. As soon as the motor run has been completed, I move the Memory Change switch to the middle position & push the Throttle stick forward. In this position the motor will not run, as the motor has been assigned to another control, on a slider switch. Then the Memory Change switch is moved to the lower position, which places the model in a landing configuration, with the Crow Braking, being activated by what was the Throttle control. This is more natural to me, than fiddling about to find a control input that you are not used to. To return to the Motor control, is a reverse of procedure above. It should be said however, that you can use the slider switches to operate the slider controls if you so wish. I have flown the model again & it is much better, but I feel I can get it much better still with more flying and adjustments.

In summing up I would say that the model is made to a very high standard, equally up to the type of quality of the CZ & German models of the moulded variety that I have put together previously.
What this type of model does is give you moulded glider quality & performance, without all the palerphernalia of any of the usual launching apparatus, that requires laying out & a large field in which to set it up in. Can we have a bigger one please say 3.3 metres span. Look forward to that, as there are plenty of models out there that would fit the bill, if the fuselage was remanufactured on the lines of the Alex, which has been very cleverly thought out so as the electric & drive components fit very well, so that they are all very safe from the damage that could be sustained from the battery being thrown forward.

Brian Austin.