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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A Model is Born.

Over the past couple of years I have designed several ‘hack’ models – “The Freddies” , nothing spectacular just basic everyday models.

All of these, when I have tired of them, have been snapped up by a flying buddy, the worlds first and only “Freddie Fan”. Recently Freddie Fan has been murmuring; time for a new Freddie, time for the lineage to have a successor, time for a Low Wing Freddie.

So, just for fun, here we have the development and build of Freddie IV – “The Crimes Against Aviation Continue”. You must bear in mind that this is no retrospective, no how I did it, but this is a forward moving, making it up and posting as I go along document. It is no forum narcissm, no platform for the exhibitionist engineer par excellance. It may all end in tears, or more likely, a bin bag, but let’s enjoy the journey anyway. And so it begins. Freddie IV.

March 2011. First Decisions.

How big says I?

40” span says Freddie Fan.

OK. We want lots of wing area – Freddie Fan likes to fly slowly – so lets have a 9” chord. This gives a wing area of about 2.5 square foot. Maximum all up weight should be 2lbs (32oz), which would give a wing loading of 12.8 oz / sq ft. Good.

Wing section. Based upon my encyclopaedic knowledge we will go with Clarke Y, because the other one is symmetrical ! Flat bottomed is fine for our purposes, and easier to build. We will have a couple of spars, some inter-spar webbing, full length ailerons, and Freddie Fan wants some leading edge sheeting on top. I guess that is the wing design done – time to bash some balsa.

Of Wings and Wood.

The wing so far. The most interesting thing here is the clamps holding everything down. These clamps were used to assemble the Pyrometers for the RB199 Turbine, used in the Tornado. And now they are stopping my wing from being warped. Nice.

Freddie’s wings are almost complete now. The leading edge sheeting is in place, and some shaping of the leading edge has been done. The leading edge has been left a little blunt as this gives more gentle stall characteristics: Freddie Fan likes to fly slowly and a gentle, predictable entry into the stall will help him greatly.

This Freddie also boasts a spar which chordwise is very deep. The earlier Freds, being lightly built, suffered from a tendency of the wings to warp, and consequently Warren Truss style diagonals had to be fitted to resist twisting. So the theory here then is that the deeper spar will resist twisting forces, as will the leading edge sheeting. There is no advantage to doing it this way over the diagonals; the beauty of designing your own is that you are free to experiment with different methods for no other reason than personal inclination.

The wood for the sheeting and spars, and in fact all of the wood that will go into Freddie is carefully selected to ensure that the strength and weight are properly distributed. For our purposes we can consider that there are 2 cuts or grains of balsa, generally referred to as A and C.

A, or tangent cut balsa is, as it’s name suggests, cut at a tangent to the rings of the tree. It has a long visible grain and a smooth almost creamy appearance. It is quite flexible but lacks stiffness and is therefore best used in tension or where curving of the wood is necessary. Ideal then for curved fuselage sides, or for D boxing Freddie’s leading edge or even for spars, where a little flex is often desirable.

C or quarter grain, has a beautiful mottled or choppy appearance and is somewhat darker than A grain. It is produced by cutting perpendicular to the growth rings of the tree; it is very stiff and consequently can be brittle. It works best in compression and resists warping well.  C grain will feature in Freddie’s all sheet flying surfaces, flat fuselage sides, wing ribs, formers and trailing edge.

Why no B grain? Well of course there is, and it is a random cut anywhere between A and C and as such is more difficult to clearly define.  It has properties of both, depending on which cut it is nearest to. B cut grain will not feature heavily in Freddie’s future.

Calculations and Crayons.

Fred’s wing, being a simple constant chord affair didn’t really need to be designed per se. Once dimensions and a general layout were decided, building could commence in quite short order. The fuselage however requires a little more care. The proportions, whilst not critical, should be within certain parameters to make for a smooth flying and easy to balance plane. The various angles and relative distances between wing and tailplane can have a dramatic effect upon Fred’s performance, or lack of.

So, it is time to break out the Crayons, and do some scribbles and sums.

We already have our starting point. The wing: 40 inches by 9 inches of grade A and C balsa; so all Fred’s remaining dimensions will be derived from this. Depending on who you read and believe there are slightly different figures available for the relative proportions of your everyday sport model, but they are all of similar value, and aerodynamics isn’t an exact science – not when I do it anyway !!

General guidelines suggest that the total fuselage length needs to be about 75% of the span, of which about 40% should be between the wing trailing edge, and the tailplane leading edge. Talking of tailplanes, the area should be about 20 to 25% of the wing area. Typically about 20% of the fuselage should be in front of the wing leading edge, but providing there is enough room for the internals, and the Centre of Gravity can be attained this isn’t critical.

By drawing Freddie out on paper and following these simple guidelines, I can set relative positions of wing, tailplane and nose, which will all but guarantee a successful first flight, and also create what will hopefully be not too obtuse a shape for Freddie. I can also use this basic drawing to develop shapes for internal formers around which the fuselage build will progress.

So, half an hours scribbling and we have to nearest thing to a design that Freddie will ever have.

From Paper to Planks.

And so the design is transferred from paper to wood, and the fuselage construction begins.

Construction of the fuselage is neither revolutionary or particularly interesting. The word ‘Fuselage’ you will not be surprised to hear, is French in origin, as are many aeronautical terms, reflecting much of France’s early endeavour in the field. It derives from the word fuselé, meaning ‘shaped like a spindle’ or simply ‘spindle’, as many early fuselages would have been. Apparently the word entered English usage around 1909.

From the pictures you will see once again the RB199 pyrometer clamps, holding everything in place and square. The pyrometer measures the temperature of the turbine blades on the Turbo Union RB199 Turbine, used in the Panavia Tornado. Turbo Union was an amalgamation of  Rolls Royce, MTU (Germany) and FiatAvio, and their only product was the RB199.  Early flight testing of the engine was performed using the Avro Vulcan, the engine being strapped underneath in a specially made nacelle, and in a nice continuation of heritage, the early prototypes of Eurofighter Typhoon were in turn powered by the RB199 before their Eurojet EJ200 turbines were available.

Sticking Sticks so they Stay Stuck.

Freddie now sports an upper deck, for no other reason than aesthetics; to make him more ‘Mick Reeves Gangster’ or ‘Galaxy Wizard’ than ‘Ugly Stik’.

The next job will be to make and attach the front former, to which the motor will be bolted. This former will be epoxied in place, which brings me neatly onto the subject of glues.

Three types of glue will feature in Freddie’s formation, Cyano, PVA and Epoxy.

Most of the build is done using PVA; Polyvinyl acetate, also known as wood glue, or white glue. It is water based and non toxic, which makes it easy to work with. Unlike the similar yellow Aliphatic Resin it has little or no ‘grab’, making clamping or pinning of parts essential, but giving plenty of time for positioning of components. PVA’s rely on evaporation to set so depending in the exact brand it usually takes an hour or two for initial hardening, and 24 hours to fully set.

Cyano, or Cyanoacrylate is the instant Super Glue favoured by many of todays modellers. Whilst it’s speed makes for a very quick build, this can, where careful positioning is needed, not always be desireable. Also, due to it’s thin nature it requires that parts be mated very accurately for best strength, and with very small models, where the contact patch is minimal, it may be impossible to attain sufficient strength. Cyano is a resin, and like all resins relies on the combination of two components to create the ‘setting’ reaction. In this case the second component is water, which it usually absorbs from the atmosphere.

Interestingly, to me anyway as a photographer, Cyano was discovered by mistake in the early 1940’s by Kodak Laboratories whilst trying to create transparent plastic. The glue was later marketed as “Eastman 910”.

Epoxy, sometimes called Structural Adhesive, is of course a two part resin, which in the case of Freddie is used where maximum strength is more important than weight. There are many classes and types of expoxy but all share a common trait – strength. In an interesting link, the RB199 clamps which have so far been essential to Fred’s construction, serve to hold a Silicon Detector to a Fibre Optic light guide whilst the Epoxy holding the two together sets. If it’s good enough for Tornado, it’s good enough for Fred.

Half Term Report.

Much of Freddie’s airframe is now built, and he is definitely starting to look aeroplane shaped. Before I go much further it is a good time to take stock. The first thing is to see how the weight is progressing.

One of the few parameters set for Fred was his wing span, and from this, wing loading, based upon a predicted AUW (all up weight) of 2 lbs. So, throwing all that we have so far on the scale (servos, motor, battery, Rx Etc) we can see that at this point Fred is around 1 lb. The remaining woodwork, and Solite covering which is destined to clothe Fred are unlikely to add another whole pound, so weight wise we are on track. Also this confirms that the 200W motor earmarked for Fred will be giving the magical 100W per lb figure to endow him with the sports performance required.

So, to sum up Fred’s half term report: a good start and showing good progress, but is prone to flirting with Miss Piper Cub, and I have had to make them sit at separate tables. Whilst not an outstanding student he has a good workmanlike approach and should have a bright future. B+

Mundane Models – a Defence.

I recently read a piece which, frankly poured scorn and vitriol upon Freddie and his kind. Why design a model just the same as 1000 before it? Can you claim to really have designed a model which eschews innovation? If you can’t be innovative and profoundly creative don’t bother.

Well, allow me to defend myself and Freddie.

Flying radio controlled models, as much as we may like to gather in clubs, is essentially a solitary and hedonistic activity. Building is largely a solitary task, and no matter how many others are present, when flying the sole  focus of concentration is on self and model. It is done in pursuit of personal pleasure, for the personal satisfaction of the build and the flight, and often, by design.

This being the case then, irrespective of what others have done, we can derive personal satisfaction from the self achievement of design, build and flight irrespective of complexity or innovation. To imply that the only designs worth creating must be innovative is akin to saying it is only worth flying if you are going to create some new manoeuvre. Flying Circuits? Why? It’s been done a million times before. I’ve eaten Ice Cream before, but it makes it no less satisfying on a warm summer’s day.

I will derive a great deal of satisfaction from the creation of Freddie, and Freddie Fan will derive a great deal of satisfaction from flying him. It’s a bit of fun between consenting adults; I am sure no one objects to that!

Incidentally I note that many of the people who deride the likes of Freddie favour the “innovative” unorthodox design, such as the canard, delta or even ornithopter.  The first successful powered aircraft – the Wright Flyer was of course a canard design, making it’s first flight in 1903, and the style remained popular with early aviators, notably being used in Santos Dumont’s 14 bis with it’s distinctive box appearance.

The first flight of a Delta winged aircraft (that is to say a Tail less Delta) took place in 1931, and is now common place, being especially favoured for interceptor style aircraft where the compromises to low speed handling are not an issue.

Flying model ornithopters have been commercially available in France since 1879, and radio controlled craft since the late fifties.  Interestingly in 1942 Adalbert Schmidt even built, and sucessfully flew, a man powered ornithopter.

“If only the bird with the sweetest song were to sing, the garden would be a quieter and less beautiful place”

Some Snaps in the Raw.

Most of Freddie’s airframe is complete now, and ready for fitting out with servo trays, pushrods and wing fixings. But I don’t intend to do any of this until I have spent some quality time with Fred and his new best friend, Mr Sanding Block. But before then, here are some pictures to get an indea of how he is looking.

Here we see the rough laminated nose block. The motor will sit inside here, front face open to the elements for cooling.

The Tail group, or Empennage if you prefer. The tailplane was originally to be sheet, the same as the vertical stabiliser, but in the interests of saving weight I changed my mind at the eleventh hour. Note the diagonals to resist warping.

So the next time Freddie will appear he will have been thoroughly rubbed up the wrong way and ready for that first, all important “pin everything together to see what it looks like” photo shoot.

Nothing to See Here. 

Like all children young Fred is now past his initial growth spurt, and is now starting to mature, with little visible change. That is not to say that nothing is happening; there are myriad details being taken care of. Servo trays made and fitted, dowels for wing retention carefully marked and fitted, wing tips added, ailerons cut, and extensive sanding.

Also at this stage Freddie is checked for accuracy. He is positioned perfectly level in both axis using a spirit level on his long nose, which I know is my 0 degree datum. By measuring relative to the flat bench I can check that both the tailplane and wing bottom are at 0 degrees fore and aft, and horizontal laterally. This is best done now when problems can be rectified with a little sanding, rather than later when adjustments may be disturbing new covering.

Fred also now sports a canopy. I had intended to carve a plug and make one from scratch, but I found an “almost fits” in the bits box. This was modified into a “fits near enough” by pulling the canopy firmly onto Fred whilst judiciously applying localised heat from a heat gun. This causes the Perspex to shrink onto, and take the shape of, the turtle and top decks.

Odds, Sods, and Skin.

So what has Fred been up to this week? Getting sanded mainly, and one or two other little odds and sods, none of which spring immediately to mind. But what is happening now is covering.

A skin of Dark Green upper, and Cream lower Solite is being first tacked at strategic points, then sealed around the edges, trimmed and then shrunk, all with the use of my trusty travel iron – lighter and less unwieldy than a domestic iron, cheaper, and I find easier to use than the long handled specialist irons. I can’t claim credit for this discovery: like most men I am married to a genius, if only we would recognise it.

Speaking of genius brings me onto two things. Firstly Harry Wesley Coover, one of the inventors of Cyano, mentioned earlier in thie blog, died this week aged 94. Secondly, Fred’s wings are now fully covered. The plan was to cover the bottom, fit the servos, feed the wires through the specially prepared little holes in the ribs, and then cover the top. You know what’s coming now. Guess who forgot to fit the servos? So, how do I get the little wire throug the little holes? Answers on a postcard please, whilst I stand in the corner repeating “Leave the wine alone when building, leave the wine alone when building . . . “

The Devil’s in the Details.

Like a caterpillar engorged with the nourishment of a thousand lettuces Freddie grew quickly through the stages above. But now we enter the chrysalis stage; nothing appears to be happening, progress has halted. But no, like the chrysalis a myriad changes are taking place.

The servos are fitted. Plopped into place, the holes drilled and secured. Golden rods are put into place, ensuring adequate support, straight runs, and roughing up at the glue points.

The control horns are fitted. Placed square to the hinge line, drilled and fitted. Did I mention the hinges? Carefully cut slots on the centre of the surface and wicking hinges are the method here.

The point I am surrupticiously trying to labour here is that the little jobs, if done properly, take time. And it is the doing of these little details properly that will give Freddie the best chance of success, and also the best chance of longevity even when subjected to the harsh operating conditions frequented by Freddie Fan.

Parting shot – wing location is by front pegs and rear bolts, great care must be taken to ensure that the wing is located both securely and accurately. Note the epoxy coating on the face of the former where the wing will locate.

RTG – Ready to Go.

Fred is finished. Well, one or two decals wouldn’t go amiss, but lets make sure he flies first.

Those all important vital statistics go something like this; all up weight, with 3S 1300mah li-po is 1 1/4 lbs, and with said li-po and an 8×4 prop he gives 150W of power, so we have cracked the mythical 100 watts per pound figure, and the motor is good upto an 8×6 prop, so we have some headroom to play.

The CG, with the battery at the rear of it’s compartment is around 25% of the chord; this is safely forward – “Models with a forward CG fly poorly, with a rearward one fly once” – but unfortunately moving the CG back will entail tail weight.

So, the only task left is to pack the bin bag, and pray to whichever diety is controlling the weather this week, and wait for some good maiden weather, or some good maidens.

Fin.

They, whoever they are, say a picture is worth a thousand words so:

A half a dozen flights in and Fred has pretty much proven to fulfil the original spec; enough power to loop from level, nice slow flight characteristics, and pretty forgiving of ham fisted fumbling.

So there we have it, not spectacular, not revolutionary, not profoundly original, but an enormous sense of pleasure and satisfaction for both myself and Freddie Fan, and after all, that is what our hobby is about.

December 2011 – Of Hedge Funds.

Hedge funds. In this case not some dubious banking practice, but the cash that Freddie fan needs to pay me to restore Freddie to his former glory after attempting to pass Fred through a hedge.

The fudelage is largely unscathed, the wing however, as you can see, has been comprehensively “stoved in” as we say round our way. It was a 50:50 call whether to build a new wing or attempt a repair. It was decided enough of the wing was intact to repair, I also decided that I am too lazy to build a new wing from scratch.

Getting it Straight.

Of course when building a wing, or anything else for that matter, it is important that it be straight and true, and this is doubly so when performing repairs with broken or mashed pieces of wood.

Here the port wing (picture right) has been raised up to the correct dihedral, and the steel rule used to ensure leading edge straightness. The wing on the board has been weighted and pinned down. So with everything fixed into place as it should be repairs can commence in the knowledge that all will be as it should be.

After a couple of hours the wing is starting to take shape. Why so long? Each piece has to be made to fit exactly to replace the shattered pieces. It is a case of measuring, cutting, trial fitting and adjusting. There have also been extra pieces fitted; extra webbing and gussets to try and put some strength back into the wing.

The picture above shows the port wing repair. An area of leading edge and sheeting was pushed in by the unwanted attention of the hedge branches. The damaged area has been cut out ant a new piece of leading edge inserted. The significanct thing here is that the new piece has been cut at approximately 45 degrees at the ends. This serves two purposes; firstly it increases the contact area over which glue can be applied, and secondly it provides more strength to small leading edge impacts.

Most of the structural woodwork is now complete, but the leading edge sheeting is still to be replaced. the above picture shows a sub rib; several of these will be made and attached to ribs at each end of the area to be sheeted. These will provide support for the 1/16 sheeting at the point where they are butt joined to the existing wood.

Here I have replaced the sheeting, sitting atop the supports. It will be noted that I have not shaped the leading edge first – this way all the elements will be shaped and sanded such that they all conform together; you will also notice the copious amounts of pins, to hold the shetting accurately in place whilst the PVA dries; it is all too easy with repairs to allow errors and inacurracies to creep in leading to the “it never quite flew the same again” syndrome. More eagle eyed people may also notice the scarf joint in the sheeting. There is a profound reason for this – I didn’t have a sheet of 1/16″ big enough in my bits box, and I am too tight (translation for the non-Yorkshire: tight = unwillingness to spend money) to buy a fresh sheet !

And so we reach the final stages, and that inevitable step which can be the make or break of all woodwork; sanding. Needless to say all the new sheeting and woodword was sanded to blend with the existing structure, continually running the fingers over the joints to check for smooth transitions.

 

Here we can see the completed repair, sanded and ready to cover. And below is the other wing.

 

The repair is more visible on this side, this is due to the differing tone of the wood, and the remains of the outline felt tip marks, once covered the repair will not be detected. It was decided at this stage to completely re-cover the wing, rather than to patch up the repaired areas.

I wont’ go into detail of the covering; it is the same process as when Fred was built. Needless to say the whole was given a final ‘eyeball’ to ensure no misalignment had crept in, and then Fred fully reassembled.

Coming soon – the final Pic, and did he fly again. . . . .

A Not Very Thorough Build Log.

I have, over the years, dipped my toe into all the facets for Aeromodelling; control line, gliding, indoor, the list goes on. All that is, except one. Free Flight Power. So, in the interests of being a fully rounded modeller, I decided that something of the FF Power flavour was called for, and that the Free Flight Nationals at the end of May should be the scene of my first foray.

The building of Freddie IV had taken much of my time leading up to the start of this project, but this was a necessary forerunner; Freddie was swapped to provide the motive power for my Free Flying Foray, an unflown, boxed,  DC Dart.

For this size of engine there is only one model for me: the Slicker Mite.

The original 42” span Slicker designed by Bill Dean, was kitted by Keil Kraft in 1947 and was designed around the then new 1cc Mills diesel. It was their first attempt at kitting a performance model, and was so sucessful that a 50” span version followed and when the Amco .87 engine appeared a 32” span variant was also kitted to suit. It is this smallest version, the Mite, that forms my baptism in power.

So, given my meagre building skills and the curvy nature of the Mite, this is destined to be a challenge, and the time constraints (2 weeks) only serve to add to the fun.

So, to quote Whitey Ford, “If it ain’t never started, then it can’t be done”. Lets make a start.

The Kit.

To speed up the build, I visited my local model shop, Nitroflight, and purchased a Ben Buckle kit.

The kit, costing around £30 gets you a plan, all the wood, and a bit of wire. Nice enough, but I was left with the feeling that it was a little overpriced. For a little over half that amount I could get a laser cut kit for a model of similar dimensions, with covering and hardware.

The Build Begins.

This being a print wood kit, the first job is to fit a new blade in the scalpel, and cut out the jigsaw puzzle of parts that hopefully will become the Mite. The clarity of the printing was good, as was the quality of the wood. In very short order a full kit of parts was produced, and the build proper ready to start. One lesson I have learned is that with curvy parts, unless you can cut very accurately (I can’t) it is easier and more precise to cut close to the line, and then sand the part to the exact shape.

Wings and Things.

This being an entirely traditional kit the build follows the standard practice of cling film over plan and build on the board. The only unusual part here is that the polyhedral spar is built first, and then each section built in turn, flat on the plan, onto the spar. This was a method I had not encountered before; trying to support completed panels in the air whilst building another was a little awkward, and of course it meant I could only build one panel at a time. Not ideal for the panic builder in a hurry. Nevertheless, the system works and I was now the owner of an elliptical Slicker wing, which incidentally, is the same wing as the Keil Kraft Pirate.

The tailplane is straightforward, and the vertical stabilisers cut from 1/16” sheet. Nothing unusual, special or demanding.

Fuselage.

This follows what I believe is called Crutch Construction. One of the distinctive features of the Mite is the curvaceous fuselage with integral pylon. Of cource this doesn’t  lend itself to a “flat on the board” building method, so a sort of horizontal slice through the fuselage is built as a frame (the Crutch) and the rest assembled onto this. A straightforward and satisfying method of creating an interesting shape. The front of the pylon is shaped from a block, which is supplied sawn to a rough contour, and then planed, carved and sanded to the appropriate shape. Very satisfying if you get it right, annoying if you get it wrong. I managed somewhere imbetween; satisfactorily annoyed.

Sanding.

And so the Mite was framed. As implied above, extensive sanding and shaping was required for the pylon front, and the whole frame sanded to provide a good base for covering. The extent and care given to sanding, and much of construction in fact, is a question of attitude: is it a case of covering covers a thousand sins, or the covering is only as good as the frame beneath? For me it is the former, so much time was spent with reducing grades of paper to ensure a satisfactory surface for covering. Incidentally flat sanding is performed with sandapaper stuck to flat pieces of MDF, the curvy bits with paper stuck to a rolling pin, I never sand free hand as my wobbly fingers give rise to wobbly surfaces.

Confessions of Covering.

At this point the frame was covered in coloured Esaki tissue, water shrunk and then doped. The end was in sight. Then, the fuel proofer was applied. I am not sure why, but at this point all the tissue covering wrinkled. Not one or two little wrinkles, but a thousand years of weather beaten exposure aggressive wrinkling. I am open to suggestions as to why this occured. This was of course entirely unsatisfactory and so there was nothing for it. I stripped the whole lot off, sanded the woodwork once more to remove any residual tissue, and sat back for a ponder.

Covering Again.

Time was running short. It was Tuesday. The Nationals on Saturday. The covering on the floor. Nothing else for it but to go with plastic film. I know many will recoil at such blasphemy, but it comes down to this: a film covered model to fly, or no model to fly. Purism is ok, but I want to fly. Cream Solite was duly ordered from Micron. Hats off to them, it arrived on Wednesday.

So, armed with my trusty travel iron – lighter and smaller than a domestic iron, cheaper than a covering iron – and a packet of new razor blades, covering began in earnest.

Solite is worked around curves easily and shrinks well, and in very short order the Mite was covered. A further hour with some Solartrim, an voila, done.

For a short run fuel  tank, a syringe was cut down, and the tank and motor fitted, so completing the panic build of the Mite.

Flying.

The free flight nationals 2011 had one defining feature – wind. However, amongst the gales and rain there was a lull, a brief calm spell on Saturday evening.

Test glides revealed a slight right turn and stall. A packing shim was placed under the tailplane leading edge to cure the stall, the right turn left in, in the knowledge that the model will try to turn left under the awesome torque reaction to the mighty Dart’s power anyway.

A test run of the motor gave a 20 second run from a full tank. The 40 year old unflown Dart was refueled and the motor restarted. A slight pause to ensure the engine was running properly and to gird the loins, and, the mite was flung into the damp Barkston sky.

The mite climbed away, with a wide right turn and circled down the field. After the fuel was exhausted, the motor cut and the plane continued on the same right hand circuit, but this time with a slight stall.

A two week panic build, a one minute flight and one happy modeller. More trimming will be needed to cure the stall in the glide, and maximise the duration, but overall a promising start to the Mite’s career; myself and the Dart are no longer Free Flight Virgins, and I can think of no better way of losing our virginity.

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