WOT, another one?

[Andy Butler]

I promised some photo's so here they are. This should illustrate that described above in case it wasn't clear.

The engine will be canted over past 45 degrees to get the silencer on the centre line of the underside. I deliberately mounted the engine at the second mark, 4 1/4 inches from the firewall. This meant I could use the 1/2" spacers at the front. I don't know why but I had the feeling that this would lock the firewall in more securely than gluing to the front. So the spacers were next after trimming the longerons to the back of the fuselage sides and a little sanding of the longerons as they were a little proud of the top at the front end where they butt up to the ply doublers.

OK, now a question, there are 3 cutouts on the top of the firewall, the side ones will be 1/4 square when it's in position and the centre one is 1/2 by 3/16. Anyone know what they're for?

[MaxG]

I used the centre cutout to route the tank tubes when using one of the square slec tanks.

Worked for me.

Max

[Andy Butler]

Thanks Max,

The ones down the edge might get a 1/4 square piece in that runs back to the next former (F5) to help lock it all together. Anyone else tried this?

[Andy Butler]

A bit more done, the firewall F4 and the next former F5 have been glued in, making sure that they were perfectly vertical followed by the inner bottom ply plate that is the inside of the undercarriage mount and goes between the sides, it's edge up against F5;

The blind nuts on the firewall were put onto ply pads which were epoxied into plave, otherwise the spikes would have protruded through the firewall as it's only 1/8 ply. Not pretty but effective.

Then the other side was offered up and several dry runs later, glue was added and the other side clamped into place.

Obviously it needs to be straight and true. Upside down like this, it was adjusted so that the front and back of the wing seat were perfectly parallel as I judge this to be the most crtical aspect. A quick check with the set square proves that the whole thing is perfectly square and the rear meets absolutely perfectly. Now got to stop myself from playing with it untill the glue is well and truly set.

[Andy Butler]

Still more done, at this rate it will be done fairly quickly.>>

First some reiforcement was carried out. A triangular fillet is added immediately behind F5 which locks F5 and F6 (the inner undercarriage plate) together. Then the two identical parts of F7 were added to the nose section, flush with the nose front and edges. These both have indents in for the undercarriage mounting bolts, the front most has these on the inside, and the rear on the outside so you know where to drill for the bolts, but having the GRP undercarriage, I'll drill the holes in that and use it as a jig to drill the holes in the fuselage so I put both parts of F7 on with the indents inside. I then took some balsa triangle from my spares box and made two braces between the fuselage sides, bottom and firewall to add some reinforcement. It probably doesn't need it but i thought why not, it doesn't add much weight. These were then epoxied in.

>>

The servo tray goes in next with the last two formers. The edges of this are reiforced with 1/8 x 1/4" hardwood. this has to be cut to give 2 x 21/4" pieces and two 1" pieces that fot around the edges where the servos screw in. These ar awaiting gluing in place.

The final step for now is to taper the end longerons from about 1" back from the rear end down to a point so that the specers added to just one side (earlier) become central when the tail is brought together.

More soon.

[ken anderson.]

aqndy-hope i'm not too late-i would line the bottom of the tank bay with some glass cloth and resin....it will save the plate comming out etc.....

ken anderson......ne...1 mod's dept...

[IanR]

Andy

I've sent you a Personal Message. Have a look when you've got a minute, mate.

Thanks. Ian

[Andy Butler]

Cheers Ken, will do. I haven't got to that part yet so access is still OK and it will fuel proof it too.

So some more done, the undercarriage was made up and just required some holes drilled as per the instructions, for mounting two 5mm holes were drilled. First I marked the centre line of the moulding, then marked out 1" either side and drilled through. This was then used to drill the two holes in the fuselage. Two 4mm holes were drilled in either side for the axle bolts, centred in the leg and 3/8" up from the bottom. The blind nuts were tapped in and the nylon bolts screwed in after shortening them to suit. Looks quite good I think. Anyway, up on her wheels for the last time until after covering.

This is prior to cropping the bolts a bit.

The two rear formers were next in followed by the servo tray. All done with aliphatic and some clamps.

Then I did some reinforcing. the underside of the servo tray had lengths of 1/4" square epoxied to it. There was a lot of the aliphatic glue rubbed off when fitting it so this was just for securiy.

The undercarriage blind nuts were epoxied in also and some more 1/4" square added as has been advised on other forums to give added strength. The tail was then pulled together and lined up with the central vertical lines on the formers.

Finally the 1/4" sheet top was added, pulling in the sides where they bowed slightly and pinned in place.

Still more soon.

[Roy Mundy]

Hi Andy looking good mate, I will watch this thread with interest as I would like to build an electric wot 4, I don't fancy the foam - e wot 4 i would sooner Build and do a conversion. I've been on to Pegasus models but I can only see Artf wot 4's not a kit ? Would anyone be able to assist me ? Thanks Roy

[Andy Butler]

A little bit more,

with the top on and drying, I tool the opportunity to start putting the tail feathers together. Once you get your head round which bit is which, it's very straight forward.

Just make sure that the gap is exactly 1/4" to allow the fin to slot in. I used one of the elevators as a spacer when setting it up.

Again, more soon.

[Concorde Speedbird]

Posted by Roy Mundy on 15/07/2013 20:28:03:

Hi Andy looking good mate, I will watch this thread with interest as I would like to build an electric wot 4, I don't fancy the foam - e wot 4 i would sooner Build and do a conversion. I've been on to Pegasus models but I can only see Artf wot 4's not a kit ? Would anyone be able to assist me ? Thanks Roy

Roy, they do the kits- here is one, a classic with the paralell chord wing. They do the others too and ABS ones which are cheaper.

CS

[Roy Mundy]

Thanks CS I have been looking for a while , Much appreciated mate

[Levanter]

I have been collecting a few projects after a long break. I am a first time buyer of a WOT 4 and picked up a Mk3 on ebay. Why? I just thinks it's iconic. There's a new Irvine 53 waiting patiently in its box and I can't wait to get building. First finish my Guillows, second Jemima, third Odalally cnc version and then the WOT. I suspect I'll be building in parallel by then.

[Andy Butler]

Hi all, back again. haven't posted for a while but the build has continued, as I needed to try one of the servo recesses in the underside of the wing and once I had a workable solution, did the same with the other wing and photographed it as I went. I've done some other bits and pieces too which I'll do first;

The fuselage top and underside sheeting have been sanded back to match the fuselage sides but not rounded off yet. I think it will easier to cut the slots for the elevator and fin before doing that.

Then as Ken suggested, the nose area was lined with glass cloth and epoxy. This extended rearwards to the undercarriage mounting plate fot a bit more strength. Following this, the last two formers were added, Former 12 which has the 1/4" holes for the wing dowels, to the rear of former 5 and former 13, the wing bolt plate, to former 9 and the sides, up against the top former (2) which has the correct angle already in place.

While I was at it, I drilled and slotted the elevators for the joiner and epoxied that into position. I always take plenty of time to do this, it's easy to do but easy to get wrong too.

I'll stop here for the moment, or the post will be too long.

[cymaz]

like it.good clear pictures aswell

[Andy Butler]

OK on with the wings. As I said, one was already done and the second one for the photographs.

Here you can see the recess in the wing marked up ready for cutting.

and here it is with the recess cut ready for lining with 1/16" balsa. I had a couple of sheets in stock so I used that so I had plenty to work with. For cutting through the veneer I used my knife which is retractable and holds a No. 11 blade. For cutting through the foam, I useda one of those snap off knives with a new blade. These are nice and long and stiff enough to give a neat cut. I conseidered using a hot wire made from some thinnish piano wire but it seemed a bit over the top as there wasn't much to remove.

This was then lined on all sides and the bottom with the 1/16" sheet with the grain running horizontally using plenty of 5 minute epoxy. Incidentally, don't throw away the foam that the wings are cut from, use the correct piece for supporting the wing while you work on it. The root side lining has a hole cut into it that matches the servo wire channel cut into the wing.

This then needed to be sanded back. To protect the veneer, I used some low tack masking tape around the hole. I used low tack so as not to lift the grain of the veneer.

Ande here it is with the servo nestled in place. I did make a slight nick in one side so that was filled with epoxy and I'll use a little light weight filler prior to covering.

I didn't use the 1/4" square hardwood bearers, I had some 1/4 x 1/2" hardwood which meant that the servo mounting screws will have a nice deep hole to screw in to. I bought a 100 cap head screws from Modelfixings a while back and I'll be using those. The mounting holes were drilled using a 1.5mm drill bit in my Dremel.

The last bit was to add the leading and trailing edge facings. Again I used the low tack tape to hold them in position while the glue dries. Don't think much of the colour scheme though!

And here is the first wing on top of the second having had the tip facing added.

So there's the tips to add and then lots of shaping. I need to shape and round off the tail feathers too so that will be next, when the weather co-operates as I'll be doing that outside.

 

 

Edited By Andy Butler on 23/07/2013 09:59:05

[karl grey]

Keep up the good work Andy because i'm using your blog to help with my MK 3 build i've just started on.

So far iv'e glued up the fuz doublers, i'll be doing my wing with the 33% larger aileron and possibly the weight reduction option.

[Braddock, VC]

I bought one of these from Hobby stores it's about my 6th one so I bought the abs/wire u/c version as I have several cowls and f/g u/c but I prefer the wire set-up as it "gives" more in the fore and aft direction than the f/g version and, as such, stresses the u/c mounting less. Having said that I always beef the u/c mounting up as a matter of course, it takes so little to do.

I have a bit of a predicament, I don't know which engine to use, my most recent wotties have been saito 82 powered which are a bit over the top, I have a saito 62, a nice new irvine 46, a thunder tiger gp 42 and a YS 45 with throttle pipe. I've kind of earmarked the 42 gp as it is a lot lighter than the others but I'm still undecided.

Have you decided what finish to apply? Film or fabric, tissue and dope or glass cloth? Another question to answer and give a lot of thought to. I think I'm going down the film route this time, just to get a nice shiny finish without having to spray and rub down, easier to fix when I break it, too.

[Andy Butler]

Thanks for the comments guys. I'm definately going to use white solarfilm and I've already got the full colour graphics - I actually really like that scheme.

So the wing tips are simply made by slotting together the two lite-ply pieces and these are glued onto the tip. There are a couple of infill pieces required, on the leading and trailing edges. If I had read the instructions properly, the trailing edge facing should have been left a little long to form the rear infill. Never mind, some odds a bits from the spares box had it sorted. Then I spent half aqn hour in the garden sanding it all to get a nice finish. Following this, the wing roots were marked up so the servo leads have somewhere to exit the wing and this again was cut out using a sharp knife.

Now it was time to epoxy the wings together. This was a job for slow setting epoxy while the wings were aligned. I have a tiny balance with an LCD readout that I bought for a few pounds at some market or other and it's ideal for weighing out equal parts of resin and hardner if you need quite a bit. The trailing edges were raised by about 1 inch, a 3s Lipo was perfect, and this was left alone to harden. So two become one...

The next step was to add the root trailing edge so first, you have to work out which way up they go as they are not symmetrical, and there is no 90° angle either. The best way is to balance the wing on the fuselage and judge it from there. You could use former 2 if you haven't got that far. Make sure you mark them so you don't get them the wrong way up.

That done, the angles were gauged and cut where they meet in the centre. I have a flexible ruler which I placed down the wing join and over the very edge of the trailing edge / aileron strip and marked the angle. Repeat this for the other and I cut them with a razor saw. Then cut off a 4" length from each and trial fit to make sure your centre angle is good. I used 5 minute epoxy for these and held them in place while it went off. To be honest, it's so warm at the moment that it only took 2 to 3 minutes to get to that gooey stage and which point you can leave them to go off fully.

The last thing is to sit it back on the fuselage and square off the centre trailing edge. There is a bit of a gap at the rear of mine but nothing that a little bit of 1/8" sheet won't cure.

So the next job is the epoxy / wing bandage - one of those jobs I really hate, it's messy and I always get a raised edge on the bandage edges and spend ages getting it sorted. Still needs must and all that.

Edited By Andy Butler on 24/07/2013 18:12:58

Edited By Andy Butler on 24/07/2013 18:15:13

[IanR]

Brilliant blog - much better than many an official instruction manual I've seen.

Looking forward to you bandaging the wings as, not having done it myself, its the part of the build I'm most worried about when I finally get round to starting my own build.

Thanks mate. Ian

[Andy Butler]

Well I put it off for as long as I could, but it kept nagging at me so the bandaging is complete. I am always a little wary after making a complete dogs breakfast out of a pair of Middle Phase wings years ago. So first things first, assemble the tools required. Here is a list of what I used, some of it is not essential but makes life so much easier.

Low viscosity epoxy resin and hardner (I used Z-Poxy finishing resin), disposable gloves, disposable plastic bowl for mixing the epoxy in, a couple of mixing sticks (I buy them in packs of 100 from the craft places), epoxy brush, low tack masking tape, a plastic glue spreader and plenty of paper towels.

First off, the wing was marked up with parallel lines drawn 21/2" out from the centre. Masking tape was then applied on the lines on both the upper and lower surfaces.

Ignore the instructions given as they mention a thin glass tape that goes on first wihich is then overlaid with a wider tape. Now a single 4" wide tape is used as materials technology has moved on somewhat.

I measured out 25g of resin and added 25g hardener and mixed thoroughly for at least a minute. Next the area between the masking tape was painted with a layer of epoxy and the glass cloth laid over the top. Start on the bottom of the wing and lay the tape with a little overlap on the training edge. I propped my wing off the work surface on a couple of paint tins. Lay the tape over the wing and let it absorb the resin. There won't be enough painted on to fully impregnate the cloth so add more, a little at a time until the cloth turns from white to translucent. Now take the glue spreader and move it gently across the cloth removing excess resin which can go back in the bowl. Then finish off with the brush and take out any high spots. The object is to fully impregnate the cloth, not saturate it. With the gloves on, you can feel along the edges and take out any wrinkles too. Flip the wing over and do the same with the top of the wing, meeting at the trailing edge. Go back over the wing and make sure there are no dry spots and that the cloth is nice and tight to the wing.

You have about 30 minutes working time which is plenty so don't be afraid to take your time and be methodical. The epoxy in the bowl (or whatever you're using) will start to go off quite quickly as the heat generated by the mix accelerates the reaction. The resin on the wing needs a couple of hours at which point it's slightly tacky and you can handle it eough to trim ff the cloth on the trailing edge before it sets hard.

I used up the epoxy by painting it on to fuel proof the rest of the fuel tank bay before it started to go off.

I'll photograph it now, watch this space!

[Andy Butler]

So here's the photo's of the finished wing - I think it's come out really well, I am so chuffed with it.

It's actually quite straight forward, just make sure you have everything to hand before you start.

A little filler and then wing fixings to do next. Then I can finish the fuselage and we're nearly there.

[Robin Kearney]

Hi Andy, you should be pleased, that looks like an incredibly tidy job!

Do you mind if I ask how how you run the servo wires from the wing panels into the center section? Did you bore a hole from the root rib out to the servo box?

With each post you make I can find myself edging closer and closer to ordering a kit. must... resist...

[Roy Mundy]

Lol me too Robin, your making a nice job of it Andy keep up the good work mate.

[Andy Butler]

Thanks chaps,

The servo wire holes are already cut into the wing panels from the root out to the servo recess. All I needed to do was cut a channel in the root end of each panel for the wires to exit. In the second photo above you can see that it has been trimmed out once the resin had gone off.