Fusion Confusion.

At the 2011 Nats I spent quite a bit of time at the ‘Fun Fly’ flightline. Whilst watching the models performing their various tasks it occurred to me how these models, all of a similar style, could make the ideal general purpose club model. Effectively that is what these models are; robust versatile and simple; what better definition of the everyday club model could you ask.

Thus motivated I set off for the trade and duly invested in an Evolution Models Micro Fusion II, this being an archetypal fun fly style model, but a little smaller, to better suit my park – flight – preference.

The Kit.

The kit consists of some very nicely laser cut balsa and ply parts, hardware, pre bent wire undercarriage, and some laser cut depron ribs. The idea being that the depron is less crushable than their heavily fretted balsa  counterparts. There is no plan provided, instead a 21 page A4 booklet is deemed  satisfactory.

Tail Feathers.

This is simply a case of easing the parts from their respective sheets, removing any little noggins, and fitting together like a jigsaw. My preferred method is to pin them to my cling film covered building
board just as if building on a plan, and then apply a small amount of thin, wicking cyano to each joint. This works because the accuracy of the laser cutting ensures that the parts juxtapose correctly, although it is always worth checking that parts which should be at 90 degrees are at 90 degrees.

A Fusion of Depron and Balsa: The Wing.

The first thing here is to produce a kit of parts; primarily ribs and webbing. Although it may seem unusual to produce a ‘kit’ of shear webbing, these pieces provide the correct spacing for the ribs – remember there
is no plan. The ribs need ‘relieving’ from their sheets with a sharp knife, and the interior cut outs removing.

It should be noted that there are three different types of rib for different places.

The shear webs are produced from the 1/16 sheets provided to the sizes indicated in the instructions. Care must be taken that the correct numbers of each size are produced, and that they are square.

Wing construction then consists of pinning a spar to the building board and marking its centre. It is then a case of working outwards placing the correct rib type, then using the correct web as indicated in the instructions, as a spacer, and working outwards.

Having gone through this procedure it is then a case of adding D box sheeting, trailing edge sheeting, and centre sheeting.

Here the D box sheeting is setting. Notice the pins, weights, and water used to form and hold the sheet around the relatively tight curve at the top of the leading edge.

The picture above, which shows the wing from below, shows the D box sheet, top centre sheet, and the trailing edge formed from top and bottom strips. Still go go are the cap strips and bottom centre sheet. Needless to say that all this work is done using PVA (or a foam safe alternative).

I attached the capstrips next. This proved to be more of a task than anticipated; the wood supplied for the capstrips although already cut to width, is rock hard. For this application this is simply not necessary, and for me turned what should have been a nice theraputic task into a chore.

Notice the pins at each end and the centre of each cap strip, ensuring bonding to the while length of the rib and therefore good adherance, in both bonding and shape, to the rib profile.

The wing tips were then added, these are simply butt joined to the end rib, and some scrap used to create triangulat fillets for support. At the rear of the tip can be seen some infills pinned in place.These match the inside edge of the tip to the wing profile, primarily to aid neater covering.

The servo trays were then slid into the pre-cut slots in the ribs and glued in place. I then added some small pieces at the fore and aft of the tray; to these I will stick the covering, and then cut out the rectangular hole neatly, giving a nice recessed aileron servo.

Also, during a quiet moment the ailerons were assembled, nothing profound here, just the same method and accuracy of laser cutting as used for the empennage. The only point of note here is the stripwood. The quality of the stripwood supplied varied from soft stock, to rock hard. In the aplications where it is used on this model, it is my opinion that nothing other than soft grained material is needed. Having used this up, there is nothing for it but to use the ‘hard stuff’ for the ailerons. Not a big issue, but I do feel this let down an otherwise exemplary kit, and made the cutting of srips truss pieces for the aileron somewhat tiresome (the wood is very hard).

Fusionalage.

As the wing is built up in stages using PVA this gives plenty of ‘drying time’ in which to commence the fuselage construction. This is started by attaching doublers (1 mm ply) to the fuselage sides, of course taking care that it is attached to the opposite side of each side (Eh?) to ensure a left and right side are formed. This should be done using a buttering of PVA and weights to stop the sides curling. Cyano will not cover the large areas necessary without drying before the parts are pieced together, and will not wick sufficiently for the parts to be ‘pre placed’.

Triangular stock is then attached around the perimeter of the sides to enable later shaping. The above picture shows how slits have been cut into the stock to enable it to be formed around the curvature of the wing fairing. Note also how the thin Cyano has wicked to different extents along the wood.

Having formed the sides the next stage is to produce the servo tray, by attaching some triangular stock to the pre-shaped plywood former. This needs to be produced at this stage as the fuselage sides are joined together using this. Also the front former is drilled for the motor – easier to do at this stage – as this is also required for joining the fuselage halves.

So the fuselage halves are joined together around the servo tray and front former. Care must of course be taken that all is square, and this is one job for which PVA is the only glue; the time it affords for positioning, checking, and re-positioning is essential.

Having joined the halves it is simply a case of sheeting in to complete the box.

Here we can see the front former in place, as well as the chin piece, which also serves a the forward undercarriage mount. Notice the somewhat boxy appearance; this will reduce when sanding begins in earnest, the triangular stock in all the corners giving good scope for shaping.

The fuselage is now taking shape; some preliminary shaping with a razor plane, and some sanding has been done. Here the vertical stabiliser is being checked for fit. It is important that any parts which are to be slotted together after covering are trial fitted at this stage, and a little extra allowance made for the covering material. Once the covering is on it is too late to do any sanding, and forcing parts together at best introduces stresses, both to the airframe and builder, and a worst risks breakage, though fortunately not the the builder.

Just another shot of the fuselage. Here we can see the servo tray aroung which the fuselage was initially assembled, and how the triangular stock is enabling me to create a curved shape to the top deck.

Sanding.

Some hate sanding. Some love it. Some don’t bother.  I have to say, I enjoy it; there is something very theraputic about sitting down with several grades of sandpaper and taking our rough hewn (hopefully not too rough!) wooden box and creating it as curves, making it flow and smoothed to the touch, taking what the Taoist would call the uncarved block and liberating the curvacous fuselage within. Enough of the psuedo poetic rambling, suffice to say I like sanding, so sanding was done until satisfied.

One note on sanding; whilst it is of course important to continually check with the eye that the shapes and lines are being formed correctly, do not underestimate the power of the finger. Fingers are far more adept at sensing small bumps or discontinuities in surfaces than almost any part of the body, so run those digits along the piece you are working frequently to check for small bumps or areas where the glue may be ‘picking up’. (At this point I would like to congratulate myself for avoiding saying ‘ run your fingers along your wood at regular intervals.’ Thank you.)

Covering.

Above are the wealth of specialised tools essential to any film covering job. Scissors for the rough cutting to size of the film; a new razor blade for trimming off excess film, and a travel iron for, erm, ironing on and shrinking.

I won’t go into detail, there is nothing really revolutionary here, the only points worth noting are to use new razor blades, and change them regulary to avoid them dragging and tearing the film, and that travel irons are much cheaper than bespoke covering irons, and in my worthless opinion, much better.

And here is the covered fuselage. This picture illustrates well the nice curves of the fusion; the curves over which it is essential to take your time pulling and working the film over to ensure a wrinkle free finish; pull the film taught, and work down into the surface with the tip of the iron, being carful not to press too hard and mark the wood; work small areas at a time and do not rush; if you are lucky you may be living with this model for a while, so isn’t it worth taking a little care and time to get it right?

Assembly.

The tailpane and rudder are slotted into place after first priming the slots with PVA. For such jobs I prefer not to use Cyano, as it’s instant nature can give rise to instant misaligment. Next the wiggly bits were hinged in place using the mylar provided. As mylar is non-absorbent, once again the Cyano bottle remained on the shelf. For the hinges I used the good old fashioned method of pinning. Slots are cut into the surface, and the hinge then inserted. A pin is then pushed through, and trimmed with some sharp end cutters. I use four pins to each hinge – two on each side. I prefer to use two as this ensures the component (aileron or whatever) cannot move laterally along the hinge line.

Motor and Undercart.

The motor was attached at this stage – a formality as the holes had been prepared before assembly, and then subsequently wired up to the speed controller which was tye-wrapped to the bottom of the fuselage to aid cooling.

The undercarriage was assembled using the pre-bent pieces, and saddle clamped into place. In the picture above you may notice some curvature to the rear leg. I can assure you that the undercarriage was assembled exactly as per the instructions on a wooden block at the correct spacing yet was slightly too long for the pre drilled holes. It could be that I somehow ended up with the ply base pieces incorrectly spaced, though it is difficult to see how. Anyway, it’s isn’t a major problem, half a dozen hands and a bit of cussin, and it went on.

Cramming it in, aka fitting the Radio and Linkages !

Now the airframe is largely complete we reach the stage of fiddling known in Yorkshire as “endless fannying about”. First the servos go into the fuselage, pretty straightforward as the tray was already fitted.

The elevator was connected unsing a golden road, and the rudder using closed loop, pull pull cables. The trick to closed loop is getting the tension just right, firm enough such that there is no slop in the linkage, but not so tight as to load the servo. Incidentally metal geared servos were used, to better withstand the loads.

Here you can just see the wires, passing through the aluminium posts, and crimped. A drop of cyano was put on the crimps for extra security, note also that biro tubes were used to line the wire exit holes for neatness and to aid smooth running.

I have to say that room in the narrow fuselage was tight, but with a bit of planning it was possible to cram in the Rx, and 2200 li-po inside, although the deans connectors ended up outside the fuselage.

The aileron servo installation is entirely conventional. One point worth note though is that I am going through a minimalist phase with my radio. No expo, dual rates or elecktrickery is being emploted at the Broughton transmitter, so all throws and trims are being set mechanically. To this end then you can see in the picture above, which shows the bottom of the wing, how here, with the aileron central, the servo arm is offset. This serves to give more up throw than down, known as differential, to aid axial rolling.

Fini.

And so in the wee small hours, the Fusion was finished – hence the picture taken in the dark !! This build log hasn’t set out to be comprehensive, but hopefully give a flavour of the Fusion’s construction. I have to say that this is a thoroughly modern kit, featuring super accurate laser cutting, and detailed A4 instructions. On construction and value alone, I am entirely happy with the kit, and would happily recommend it to anyone seeking a similar style aircraft. Oh yes, flying, hmmm . . . . . .

Into the Gale.

The next day was a gale, ish. But you know, sometimes, like hysteria, when the mood takes you it will not be denied, so a flying we will go.

The field was to boggy for a proper ROG so a hand launch was to only option. Flying on this day was madness, so needless to say I was alone, so it was to be a single handed launch. Model held aloft. Last wiggle of the wiggly bits. Throttle up with the chin. Deep breath. Lob.

And away she flew, straight and level. Perfect. Whilst it was too windy for proper trimming all seemed well. I had the motor slightly under propped for this initial flight, only generating about 150W or so of the 300W of which the motor is capable, but even at this, the model chugged along quite happily, able to loop easily from level flight, in a very tight fashion, a rolling axially at the rate of about 3 a second. A lull in the hurricane (it was windy!) provided a landing opportunity not to be missed and that thick high lift section enabled the fusion to be slowed right down, and the forward raked undercarriage prevented nosing over when the wheels hit the bog that was our patch.

I am confident that the fusion will fulfil its destiny to be my general purpose model, and over subequent flights will refine the trim and set up to suit my flying style.

(Photo: J.A.Hind)

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