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Phil's funfighter


Phil Winks
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Time to start the next episode in my 2015 mass build saga

and still

Till the pilot briefing at Greenacres, so hopefully plenty of time yet,

These plans are from Tony Nijhuis designs and the RCM&E build article is downloadable from the same page.

My chosen power train is as follows

Motor, ESC and servo's are unfortunately discontinued I've just discovered so hopefully I'll have no problems with the ones I bought, however almost any 9g metal gear analog will be good. hopefully a 2200Mah LiPo will act as fuel tank and prop will be, subject to tests, an 8x4 (possibly a folding prop to avoid landing damage),

Anyone who built the Nigel Hawes Tucano 2 years ago will be familiar with the wing construction as its his popular flat sheet design and the panels are glued, cramped and drying as I type.

Edited By Phil Winks on 27/01/2015 18:24:54

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Before you start get the major componets on the plan photo copied several times.

Right once the wing panels have dried then things proceed like this.

1st you'll need two copies of the wing template from your Photo copies of the plan, these are coated one side with photo mount spray adhesive which when dry will allow you to stick them to the panels thus. Note one template is upside down this is because only one wing template is show on the plan and we need, obviously a handed pair

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So taking your scalpel, c/w new blade, in hand cut close, but not to close, to the template and remove the bulk of the waste,

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Note I've left a goodly amount at the root to give me something to go at when I cut the dihedral angle for the centre line butt joint

Then gently attack these with a davids razor plane, c/w new blade set fine, and sanding block to reduce them to the outline of the templates, place them back to back when done to ensure they are identical,

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Finally for this section cut dihedral angle on the root, I usually create a jig to place a sharp razor saw against making the cut relatively easy to make

picture 004 funfighter 2015.jpg

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And on with the wings, the next job is to cut the slot for the dihedral brace, make sure the two wings line up perfectly

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Now cut the short sides only of the ailerons, then carefully score along the lines showing the limit of chamfering on the templates and remove the shaded area

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Now taking your sharp finely set razor plane cover your workshop floor in shavings taken from the now exposed areas of balsa to get a rough, well not to rough, profile

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then tidy this profile up to that shown on the plan with a good size 240 grit sanding block, remember through all this profiling to keep the wing face up flat on the bench to help support it.

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now clean the shed floor and have a cuppa to wash the balsa dust down.

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the next stage will see us prepare the ailerons for mounting, 1st cut the ailerons free using a sharp scalpel and straight edge to cut along the long edge joining the earlier cuts

picture 014 funfighter 2015.jpg

then we need to make the torque rods from a pair of 2mm push rods, bend the threaded end 90 degrees then having measured to the next bend make it another 90 degree bend but at 90 degrees to the threaded section too, the picture explains better, remember a handed pair are needed again, also we need to make a channel to take the torque rod, this runs from the inboard edge of the aileron towards the centre of the wing. They should turn up through the wing as far apart as the width of a double servo arm on your chosen servo so half that distance from each wing root, the easiest way to cut this channel is to use the threaded end of a push rod as a file to make the groove.

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the torque rod needs to be set into the wing so that its centre line is in the centre of the wing depth wise.

Next you will need some of this

picture 017 funfighter 2015.jpg

and a small amount of 20 min epoxy, and whatever you decide to use as a cap strip, my preferance is 0.4mm epoxy glass sheet

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So finally tonight, fixing the torque rods in, 1st grease the rods lightly and set aside, mix your epoxy, then place 2 small blobs of epoxy in the channel approx 10 mm in from each end and place the relevant torque rod in place, scrape of excess epoxy, then lightly epoxy the FG sheet over the channel and clamp all up till set

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when its all set it should be easy to twist the torque rod along its axis to free it up and you'll have a perfect bearing formed by the epoxy.

Tomorrow I'll look at joining the wings.

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Time to join the wing panels and fit the servos, 1st I needed the dimension for a packing piece to go under one wing tip, so that with one panel flat on the bench and the other pack up the dihedral was set correctly, now you can get the calculator out and using the sine rule work it out or, at this size draw it out on paper, my preference is to punch 2 numbers into my triangle solver app on my phone and the answer is there in nano seconds.

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given that the distance from the wing centre to the start of the tip section is 300.5mm and, from the dihedral brace template the angle of one wing from level with the the other flat is 9 degrees this app has simply and elegantly given me the answer. 476.6mm give or take,

Next I marked out, from the drawings, the position of the servos and cut into the wing to allow them to sit as low as possible without sticking out the underside, bearer blocks were then cut to size remembering to cut the bottom to suit the wing dihedral, now I dry fitted everything and when happy committed to 20 minute epoxy and voila

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detail shot of the servo mount

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and the same of the block holding one wing tip up

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when this was all set I took the time to set the servos in place as its easier to get it right before I fit this to the fuselage and space becomes limited, I am able to clearly see the limits of the inside of the fuselage from the width of the servo bearers

here we go all set and centred, the underside of the servos are protected by a 0.4mm GF sheet glued to the underside of the wing, this will be blended in during the paint preparation phase

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I will now remove the servos and continue to the primer stage prior to starting on the fuselage.

Edited By Phil Winks on 01/02/2015 14:46:36

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I've done a bit of the pre paint prep and got the 1st coat of primer on, also the ailerons are fitted, and I have an apology for any of you that haven't hinged control surfaces before I went ahead and didn't photograph the process, however when I get to hinging the elevators I will do a how to video, well a how I do it video!

Normally the control surfaces would't be hinged till after covering but as I'm using paint not film to decorate I'm happy to do them 1st.

You will see I masked of the area where the fuselage sides join on to the wing as any glue joint works better on bare wood than it does onto paint, on the later it will likely simply pull the paint of when pressure is applied

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This is the 1st coat and is due a rub down with 400 grit wet or dry and a light weight filler in the blemishes and open grain this coat and rub down reveals. Then another two or three thin coats with a rub down with 800 grit between before a final rub with 1000 grit and then the colour starts to go on, in my case a traditional Mk V camo scheme and possibly invasion stripes, for those who think this may be a lot of coats of paint, its half what I would aim for if I wanted a pristine perfect finish, this being a funfighter and winter hack it's expected to have a rough life and does not warrant a perfect paint job

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I hope so too need to be able to get on your tail cos the Mkv, along with all the early spits couldn't bunt out of the way of a 109 due to the fuel system so need to see you coming if my cannons are to be brought to bear effectively devil mind you I may fit a captured BMW fuel injected engine to catch you out winkna that would be just wrong frown

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Well here we go with the fuselage,

As with the wings I cut out the photo copies of the formers etc. and using photo mount spray glued them to the relevant thickness balsa sheets,

picture 025 funfighter 2015.jpg

Points to note here, the fuse sides were actually cut before I profiled the wings so I could match that profile to the fuse sides, helps with a good glue joint. also if, as on this one and many others, the fuse sides curve in towards the top/bottom they will be slightly larger than the side view on the plan, Tony has allowed for that here by adding a dotted line for you to cut to which is slightly above the actual fuselage side as per plan, hopefully you can see what I mean in this pic.

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Then following the build notes the formers were glued in place on one side and then the other side added ensuring everything was/is square, Point worth mentioning here Tony has detailed this part of the build very well in his notes so they're worth reading a couple of times before cracking on. So triangle stock and formers added, along with the second side and a shape is starting to form.

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then as detailed the turtle deck was added in the form of a sheet of 6mm balsa then one of 3mm, there is a gap needed for the tail plane and to achieve this I tack glued a piece on the tailplane seat, added the turtle deck over it and profiled it before nipping through the tack gluing with a razor saw to release it. then the forward section top deck was fitted

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Finally before I start to profile the forward section, cos it's easy to mark while all is square I cut the vertical cuts for the battery and motor hatch

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So hopefully during the week I can profile all this prior to fitting the tail feathers and temp fitting the elevator push rod prior to sheeting the bottom rear section and attaching the wings.

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Moving on, I'm now profiling the fuselage forward section, 1st the motor mount former needs to be cut to suit your chosen motor and carefully epoxied in place. Then using the plan, and side elevations from your copy plans make a template and transfer the outline onto the top sides and bottom of the currently square sided fuselage, then remove the excess balsa outside the side and top profiles with a combination of razor plane and sanding block, this will give you the basic shape, then mark the extent of the curves along top sides and bottom,

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then using these as a guide, and with reference to some good photo's of the real thing, sand/plane away the excess wood to blend the curve, as a wood carver once told me, "when carving an object simply remove any wood that doesn't look like the finished object".

eventually, and it can be a slow process, you will see the shape of a spitfire start to emerge.

picture 042 funfighter 2015.jpg

I use 3 basic grits on the sanding block during this process, 80 grit for quick removal of large areas, 24 grit for general fine finishing, and 600 grit for final finishing, also a sheet of 600 of the block is useful for careful final finishing of curves to prevent any flat spots. also it can help to have some external profiles taken from the former drawings to check you have the right profile at those points along the fuselage.

Edited By Phil Winks on 14/02/2015 00:04:03

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Thanks Alain and Colin, I aim to please.

Cracking on following the process detailed above I've near finished the profiling of the fuselage.

I have added a 3mm balsa ring to the front of the motor mount to take up a 4mm gap between the spinner and mount. Better than cutting 3mm of the motor shaft.

Also I've got the elevator push rod fitted prior to fitting the bottom sheet aft of the wings, this needs to be fitted now as fitting after the bottom sheet is near impossible if your to achieve a good straight control run from the servo to the exit point. The balsa around the exit slot and the holes in the formers has been hardened with thin cyano to reduce the danger of them wearing and making for a sloppy control run. the holes are made by easing the rod through the balsa while still soft, it helps to sharpen the end first. The Z bend for the servo end is made with the rod in situ using Z bend pliers then clamp this bend to the side of the fuse at the position where the servo will be and mark where the rod exits under the tailplane, this is where the 1st of the 2 45 degree bends will be made, the second is to bring the rod back parallel to the centre line of the fuse. I hard soldered an M3 threaded extender here to take a clevis though a nylon clamp on nipple could be used as suggested on the plan.

Also the hatches have been cut out by joining the previously made saw cuts by cutting along a straight line with a scalpel, the cockpit hatch has a locating rod at the rear and a spring catch at the front for battery access and the cowl hatch has a Grp plate tongue at the front and a servo screw at the rear, once again the balsa has to be hardened with thin cyano.

Now the pics.

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what a productive weekend she now looks like this

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the bottom sheet on and profiled wings fitted, tail feathers fitted servos centred and control rods fitted all surfaces set centre, just need to fit the motor, esc and Rx and some decorating and a few home spun decals and she'll be ready to fly and 138 days to get the maiden in, along with the atom and Dawn flyer from last year.

Points to note here, when fitting the wings and tail feathers it is essential to get them all square, the use of a tape measure is essential, It's vital that the rudder is properly aligned as there is no trimming it once fitted, being a "bank and yank" flyer!!

I should point out that there is no intention to fit a pilot figure and the cockpit glazing is going to be painted on to the Vac formed canopy.

Edited By Phil Winks on 15/02/2015 17:58:21

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