Steve McLaren

Fitting the top skins to the wings was, for me, the most nerve wracking part of this build. It seems to me that you have just one chance to get it right. If you get it wrong, I'm not sure that you would be able to rescue much from the carnage. So I put a bit of time into the preparation Despite my reservations, I did find that it was indeed possible to cut an 18 inch long tapered wedge from 0.8mm (or thereabouts) to zero. Actually mine faded away at about 15 inches, but I figured that was good enough. So I taped it to the bottom of one wing under the aileron spar and running towards the root, and pinned the wing down firmly. I used PVA adhesive, to give myself as much working time as possible, and set off with a few weights and lots of pins. When I removed it from the board a few hours later I was initially really pleased with the result, until I spotted a spanwise crack of about 5 inches long in the upper skin near the aileron spar. If you look on the photo you can just about see it was there when I'd finished the pinning, but I didn't notice it until later. (It runs inboard from the 4th to last pin on the aileron spar). There's not much curvature in that region, so I decided that it must have been a flaw in the original sheet , and I was just unlucky. Anyway I squirted a bit more PVA in it and weighted it down with a steel ruler. That seems to have fixed it, I' don't see any reason why it shouldn't be just as strong as the other skin joints in the wing. The 2nd wing skin went on without any such problems. Having fitted the leading and trailing edges, and sanded to shape. The wings look like this. At this point I thought it was all going so well. Then I decided I'd better check the two wings back to back against each other - check the washout angles etc. When I did this I found the washout angles looked great, but I found that my wings were slightly different lengths! How could this be? I had initially marked them out on the bottom skins from the same tracing paper template, so I couldn't understand this. After carefully checking against the plan, I found that my left wing is more than 1/16th inch shorter than it should be, and the error is all at the root end.. Looking back on it, I think I just wasn't careful enough with the positioning of the root rib. I marked out all the ribs on the skin, except the root rib, which I just positioned against the cut edge of the skin. I still don't really understand it! Anyway , to fix this I have glued a hard 1/8th balsa packer to the inboard end of the left wing. My plan is then to sand it down to the correct thickness before I join the wings together. Since I planned to do a fibreglass skin joint at the centre anyway, I'm hoping this mistake won't have too adverse an effect on the overall strength of the wing, and it will be hidden below all those under-wing fairings anyway. So, back to the fuselage. I thought that once I'd got the sides joined together I was making good progress. But there's a lot of work in this fuselage! I've put in some hours this weekend on planking the upper fuselage and cutting all those 1/2 inch blocks to shape to fit between all the formers at the front end. I also added a few 1/16th strips on the inside of the triangular sections, since mine had gone a bit crumbly after being over-zealous with the saw cuts. I'm hoping these will hold everything togehter better when it comes to shaping the fuselage later. So this the planking. And this is the block work finished at the nose end. I tried to make these as 'hollow ' as I could, but it's difficult to judge where the outer profile is going to end up, so I erred on the safe side. I also added a scrap former half way back inside the planked section, as suggested by Andy. So, maybe some shaping in the next few days?

So to the wings. I built them pretty much exactly as the plan up to this stage (even got the spar webbing the right way round!), I did deviate from the plan a little on the aileron torque rods. I decided not to bother with the carbon fibre reinforcement. My logic was that, being 'torque rods', they shouldn't really need the bending stiffness. And the construction was a bit simpler without the carbon. I just wrapped a bit of glass cloth and resin around the wire ends to bring them up to the inner diameter of the aluminium tube. I'm hoping that might have saved me a couple of extra grams! Before applying the top skins, I needed to think about the wing joining. Again I decided to deviate slightly from the plan here. I decided that since most of the load in these wings is carried in the skins, it would be a good idea to go with Andy's suggestion and reinforce the skin joints top and bottom with glass cloth. Once you decide to do this, I'm not sure that the wing joiner ply brace is really going to add much. But I couldn't bring myself to leave it out altogether, so I'm going with a shortened version which just spans the inner bay of each wing, and adds a bit of shear strength to the joint. To make this easier to fit after wing joining, I pre-cut the slot in the bottom skin and cut halfway down through the ribs from the top surface. Hopefully this will preserve the stiffness of the structure for the skinning operation, but make it easier to fit the brace from the bottom later.

So this is my fuselage today, joined together. There's not much to say about joining the rear section, except that I drilled a few extra holes in F6 and F7, and sanded the inside face of the triangular sections a little concave between F6 and F7 in an attempt to save a few grams at the back end. I've also been thinking about whether to bother with the rudder. From what I read, it sounds like most people are going to go for the rudder option. But I'm very tempted to leave it fixed (as originally designed). My logic is that, being a relatively in-experienced, casual sort of sport flyer, I'm not convinced I will make much use of the rudder, and I think I would benefit more from a lighter model which works in the lightest possible wind conditions. That way it is likely to get flown a lot more often. I shall keep thinking about it, but I will have to decide quite soon.

Thanks Phil for the info on where to find some lightweight pilots. I didn't fancy the 'Pete's Pilots' version as they sounded a bit heavy, and I'm trying to build as light as I possibly can. I was messing about trying to create something from a polystyrene ball and a few bits of foam sheet, but it wasn't going well! I'll probably just end up adding nose weight anyway so it's probably a waste of time, but worth a try. Were these the PTS 4 pilots? I hope so cos that's what I just ordered!

Thanks RedBaron for the lead on clamps. I shall go check them out in B&Q today. No matter how many clamps I have, I never seem to have one that's quite right for the job. On the Ivinghoe PSS day, I don't much much about it myself. I'm a relatively new member and until now I've not had a PSS model, so I've never been to it. I'm not sure whether it's a closed-to-club event or whether visitors are welcome, so I'd better check with the committee before I go publicising it on here (Oh it's a bit late for that!).

Right, after a bit of research on 'albums' I think I can attach some photos:- No 1. Too many saw-cuts in too soft a bit of balsa. No 2: Bending the fuselage sides with a workmate That's enough for today. I'll write some more about the wings tomorrow.

I guess there are going to be lots of these blogs, so in order not to be too repetitive, and since I'm running a bit behind some others with this build, I'm going to concentrate on things which I have either done differently, things which have gone wrong, and things which I think might be of interest to other builders. This is my first build blog. It's also my first PSS model. I've built a few models of conventional balsa construction in recent years, but always from 'full' kits. This is my first experience of a Traplet 'wood pack', and my first build from a plan since I used to make control-line combat wings in the late 70s! So it should be interesting. I started construction a couple of weeks ago - I wasn't initially aware of the 'official' start date, but also I'm working to a shorter schedule - hoping to be ready for the Ivinghoe PSS day in mid April. So, I'll start with the fuselage. Mistake No 1: I didn't check that I understood what all the parts in the wood pack were before I started building. So having joined the fuselage sides together I have found that there are 2 small parts of the upper fuselage sides which I haven't used. I just assumed that the guys at Traplet had decided that this bit of the fuselage side would all be sanded away, so they must have decided it wasn't necessary. Anyway, it seems to have worked OK without these bits. It was a bit more difficult to position the forward triangular sections without a clear reference, but I managed. Mistake No 2: I had read the info about the error in F1, but then I forgot to do anything about it until after I had built it into the battery box assembly! - but that was easily fixed. Mistake No 3.: I was a bit over-zealous with the saw cuts in the triangular sections. I couldn't get triangular section stock from my local model shop, so I made my own from 2 strips of 1/2 inch and 2 strips of 3/8 inch, and then razor planed them to a triangular section. I selected the lightest wood I could find ,as advised by Andy. I started trying to make saw cuts at about 3/16 inch spacing with a junior hacksaw, but this just seemed to rip big chunks out of my carefully prepared triangles. If I can figure out how to use this forum software, I'll add a picture! So I've got a bit of repair work to do there. I discovered later that you don't need that many saw cuts. because it's not that difficult to bend the fuselage sides. It requires a fair bit of force, but I discovered it was relatively easy to do if you've got a 'Black and Decker Workmate' or similar. This works very well as a controlled parallel clamp, for pulling the fuselage sides together onto F2. Then If you've got a a big spring clamp, you can use this to pull the 2 thin strips at the nose onto F1. (I was going to add a picture here too but I can't see how to do it!) Can anyone advise?