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Another Andy Blackburn PSS Canberra

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Andy Blackburn12/04/2018 08:42:24
515 forum posts
487 photos
1 articles
Posted by Devon Slopes on 07/04/2018 19:05:02:

The First Plank. I'm trying to follow Andy's instructions as closely as possible as this is my first from-the-plan build, and apparently there has to be a small ceremony to mark the laying of the first plank. As you can see I've managed to source a "Keep Calm and Carry On" mug, but will the build be irrevocably compromised by the use of Chocolate Orange rather than ginger nuts?

...

The sharp-eyed will spot that I've started with a plank at the top (not on the side), I'm not quite sure why.

Well...

I don't know about the build being irrevocably compromised, but it might get a bit messy as the ceremony does involve dunking...

There's nothing wrong with starting the planking at the top (and it's easier to do that, actually) as long as great care is taken to keep everything straight and square; the basic un-planked structure is a bit wobbly, so I advise checking straightness and squareness after adding every plank until a reasonable number of planks have been installed.

Devon Slopes27/04/2018 21:31:06
67 forum posts
43 photos

Plodding along planking. I'm making gradual progress planking. I took to heart Andy's warning about keeping the fuselage straight and square as the early planks go on by re-using all the 90 degree jigs when I pinned the fuselage back on the building board. The jigs had to be cut a bit, though, to make them fit around the structure. My plan for broader planks than Andy failed, because my balsa stripper will only do 7-8mm strips. Rather than fashioning both edges of the plank, my tendency to idleness has led me to shape only the edge which is butting up against the plank which is already on the model. But, as I'm doing one plank at a time I can wet the planks, and bend them, which makes them slightly easier to handle.

As I started at the top, I pinned a spare plank around the waist of the fuselage so I could see where I was heading. As this picture makes clear there was an impending problem, how could the remaining planks taper to a thin enough end to all meet at the nose...

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As you can see I solved this by making some planks which do not reach the nose, so it looks like I might succeed.

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Devon Slopes18/06/2018 17:22:41
67 forum posts
43 photos

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Other things have been keeping me busy, but when I get 15 minutes or so I lay another plank, so I’ve now reached the stage that I have laid the last plank I can lay with the fuselage still pinned to the building board. If you view it from the front you can see how my technique has improved. On the top side of the picture you can see the quarter I did first, where I was forced to make some of the planks shorter than full length. On the bottom side I got it right, by thinning out the planks rather brutally. The mistake I made when thinking this out earlier in the thread was to assume that all the planks thinned in the same way. Actually, because the fuselage is asymmetric top-to-bottom the top planks need to thin more towards the nose than the bottom planks (and vice-versa for the tail region). Though before anyone commits themselves to this plan they may want to wait until I have proved this hypothesis by completing the whole job!

(Apologies for the sideways pictures!)

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The tail bay is a bit of a puzzle. The bottom part of this has to be filled in before the fuselage comes off the board, I assume to make sure you build it straight and true. This picture shows the current position, and two of the laser-cut pieces you are provided with. One is F11 (the former shown right on the end of the keel piece). I think this should be completely circular (save the slot); I suspect the smaller radius part on the bottom originates from Andy’s original plan when the planking on the bottom was going to extend all the way to F11.

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The other part shown is labelled “tail bay infill” on the balsa, and is one of four. The instructions on the balsa say laminate these together in pairs. The oval holes are a little misleading. I tried threading snakes through these, but actually they simply mark where the snakes emerge from the balsa. So, the plan is to make a circular F11, assemble the tail plane and fin, and see if this all fits together.

Andy Meade19/06/2018 10:02:22
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2809 forum posts
722 photos

The planking still looks neat to me. It'll look even nicer once the sanding is done - you'll not want to cover it!

Devon Slopes28/07/2018 10:13:44
67 forum posts
43 photos

Thanks for the comment Andy. Covering is actually preying on my mind at the moment, as my main experience is with film, but it always seems to end up bubbling in the heat, so maybe I have to take the plunge and learn to glass.

Anyway, on with the build. I’ve assembled the tailplane and fin. Since the tailplane has dihedral, the edges which join the two halves together have to be sanded to an angle. The block of wood shown below happened to be just the right size to allow me to sand the angle in.

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Then I had to make the supports for the tailplane. As I said in my last post, you are provided with four of these which you laminate in pairs. Rather than trying to sand the top edge of these pieces at an angle to match the dihedral of the tailplane, I decided to mount these pieces at a slight angle, rather than vertical. They are then a little too deep at their front end so I shaved a bit off. You also have to cut channels for the snakes, and if I was doing this again I think I would glue the laser cut ellipses back in before cutting the channels. Finally F11, the former right at the end of fuselage was designed when Andy thought the bottom tail region was going to be planked, so I made a new one which is round. You can see all these bits in the picture below.

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Peter Garsden02/08/2018 17:21:16
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1836 forum posts
1446 photos

I'm watching this with interest as I have halted mine at the wings whilst I do the Hurricane which is very nearly finished.

I agree with Andy - very good planking - much better than what I will be able to achieve I am sure.

Andy Blackburn07/08/2018 08:51:55
515 forum posts
487 photos
1 articles
Posted by Devon Slopes on 28/07/2018 10:13:44:

Finally F11, the former right at the end of fuselage was designed when Andy thought the bottom tail region was going to be planked, so I made a new one which is round. You can see all these bits in the picture below.

dscf4633.jpg

In my own defence, I feel that I should point out that I'd corrected that on my own set of printed parts but obviously forgot to change the plan, which is what Sarik obviously used to generate the new parts. Mea Culpa. smiley

A.

Edited By Andy Blackburn on 07/08/2018 08:52:38

Devon Slopes29/09/2018 20:23:02
67 forum posts
43 photos

Not to worry, Andy, it's a trivial piece to make.

So I pinned the supports for the tailplane in place on the fuselage. I then put the tailplane in on top, with a layer of plastic between the two. I then pinned the tailplane supports to the tailplane. Removing the pins from the fuselage then allowed me to remove tailplane and supports as a single assembly like this.

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I checked the supports were seated properly on the tailplane, then put glue in the appropriate places on the supports, and re-assembled the tail as shown below. The wooden pieces on the tips make sure that the tailplane is held at the right angle (i.e. the equivalent of horizontal). Andy, if you are listening, is there any way of checking I have the decalage right? Should the tailplane be a zero incidence?

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When it’s all dried you can take the tailplane off, and it looks like this. All I have to do now is block in the bottom part.

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Peter, meanwhile, is making fantastic progress. We started at the same time. He started on the wings first, but completed those months ago, and has now overtaken me and seems to be almost finished. Oh, and in between he’s managed to complete a Hurricane. How do you manage it Peter? My only excuse at the moment is assembling an electric fuselage for a glider.

Peter Garsden30/09/2018 07:30:25
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1836 forum posts
1446 photos

Glad to see you are making progress Devon Sloper - you are doing the bit I made a bit of a Horlicks with by gluing on the top pieces too soon. You can, however do it that way. It just means inserting the tailplanes through slots rather than from above. I did it that way because I am finishing with Solarfilm and had to cover them first.

How do I do it? Late nights and early morning mainly, having a workshop in the house which is a converted garage room, and being extremely unpopular with my other half who thinks "I am obsessed with playing with toy aeroplanes", something which has sadly slowed me down over the summer, so stick at going slowly,and carefully which you obviously do.

The Hurricane, however was a bit success, and a real hoot when we all flew together at the Orme - highly recommended. It flies like a dream, as well as the Canberra, I am sure knowing Andy's designs as I do.

Edited By Peter Garsden on 03/10/2018 18:50:00

Devon Slopes27/01/2019 11:05:20
67 forum posts
43 photos

No, this build hasn’t been abandoned, just that nothing has got done for the last two-and-half months due to other commitments, which included the new fuselage for an electric glider.

The wing joiner. Andy Blackburn says that “if you’re planning to play rough with your Canberra” you should go up a size in the wing joiner. Slopes Junior thoroughly enjoys his slope aerobatics, so I suspect I need to do this. The standard joiner is 6mm OD carbon tube with 4.5mm carbon rod inside it, so I’m going to 8mm OD carbon tube, with 6mm carbon rod. This means I will have to open out the holes for the joiner in the wing ribs.

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Attaching the wings. I’m also wondering how to attach the wings onto the fuselage, which Andy recommends doing by tape, but says you can also do it by using a Multiplex Multilock plug and socket, but if you do so you need to make hard points to put them into. Not quite sure what this involves, but it looks like I need to work out how to do this before I complete planking the fuselage. So, I’ve dry assembled the starboard wing laser cuts parts so I can see what’s going on. It all seems to go together nicely, though you have to make another rib R4, which is easy to do using the sandwich method, with the laser cut R4s as the templates.

Devon Slopes02/03/2019 22:08:09
67 forum posts
43 photos

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This is how I opened up the holes in the ribs for the wing joiner tubes from 6mm to 8mm. Because the side of the tube has to just touch the main spar, the centre of the new 8mm hole is offset forward with respect to the old 6mm one. So you can't simply open up the hole evenly all round. So I made two ply templates with 8mm holes made in the right place by comparison with the plan. I then "sandwiched" all the ribs together using the incidence tubes, double-sided sticky taped the templates in place and them opened up the holes using sandpaper wrapped around a pencil.

Note quite as elegant as it sounds, as a little more sanding had to be done to get the tubes in once the inner wing panels had been constructed, but more of that later.

Devon Slopes08/03/2019 20:38:21
67 forum posts
43 photos

Multiplex Multilocks. A decision almost made. I think I'm going to try holding the wings on with the multilock connectors. I could not convince myself that the magnets would have enough grab (the held 500 grams weight, which is less than my calculation for the likely pull); though they do work for Peter. So, here is the layout I'm thinking of. I have a ply plate that glues onto a former and longeron in the fuselage which holds the barrel of the lock, and a piece of ply in the wing which should transfer any force fairly directly to the wing spar (there is wood to go in above and below the spar, which should help further). I'm going to put the peg into the wing and then try it against a test piece to see if it works. I can't use the fuselage for the test as I don't know how deep to glue the barrel in until I've sanded the fuselage. Thoughts (as ever) welcome.

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Devon Slopes01/06/2019 20:06:56
67 forum posts
43 photos

Structure around the incidence tubes and spar. So, here are the inner wing panels almost complete, at the stage of fixing in the spar and incidence tubes. You can see all the strengthening around the tubes Andy talks about. The incidence wires and main spar are slightly over length, I’ll trim them when I know how wide the fuselage is after sanding. You can also see the parallel lines I drew on masking tape on the building board to make sure the wing roots are parallel.

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I made the mistake of scrounging the balsa which fits around the main spar from the wood which the wing tips are cut from, but then realised this must be soft balsa, and so made new ones from some other scraps from the kit. You can also see the hard points for the Multilock wing joiners (one of which has a Multilock plug in it) close to the spars. Also, I have faced the wing roots with 1mm ply. The advice is that this will protect the root from damage, but also you have to force a plastic wedge between the fuselage and the wing to disconnect the Multilocks, and I’d rather do that against ply than balsa.

And this is gluing the main spar to the bottom outer wing skin.

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Devon Slopes29/04/2020 18:38:09
67 forum posts
43 photos

Hmm, ten months since I posted here. Most of the reason is that I decided I needed to build a 3 metre e-glider, which is now complete. Need, of course, is an interesting word when it comes to model aeroplanes, but I’m sure you will understand. The other interruption was the small matter of breaking the wing on my smaller e-glider, which involved assembling a new wing. But both these projects are done now, and in between you can see some progress has been made on the Canberra.

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Of course, the world of Andy Blackburn Canberras has not stood still whilst my (limited) building skills have been being applied elsewhere. Mike Q started a build blog, which uncovered that both Scot Edwards 2 and Paul Ashford have completed models.

So, on with the build....

Mistake 4 was placing the inboard end of the aileron one bay too far inboard. I discovered this when cutting out the aileron, and fortunately had the picture shown below of what it looked like before the top skin went on. I've managed to bodge it back to be correct, but it was not my finest moment.

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Devon Slopes06/06/2020 13:45:39
67 forum posts
43 photos

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A slightly unusual view for this post. Looking from the back of the fuselage forwards, the slot being where the forward part of the tail fin will fit. This emphasises how foreshortened the picture is. To the top right is the area of the fuselage covered in the planking. As you can see the planking is now complete, and a lot of the sanding of the planks is now done. The bottom left is the tail bay area. Filling all this in felt a little as though I was making it up as I was going along, but its now done and roughly carved into shape. Now some more serious sanding is needed.

Handling the fuselage showed up the problems in my planking. Where planks had not glued to each other the fuselage would flex under hand pressure. Easy to cure though, by brushing white glue into the gaps. I was worried about cutting out the hatch, despite the marks I'd left all round the gap. So before the final planks went in I cut through the formers, so its now held in place largely by the planking.

Devon Slopes25/11/2020 18:17:38
67 forum posts
43 photos

Any Advice on Canberra Colour Schemes?

Progress is being made, and so I'm beginning to think about colour schemes. One of the things I learnt from building model railways is to pick things to do which lie within my modelling skills. Hence I was pleased to find that there is a colour scheme for the Canberra T4 which has all-grey wings. That should not be beyond my abilities with a spray can! But does anybody know if they were really grey, which is apparently as shown here? Or were they actually this greeny-grey shown here?

Alan Gorham_25/11/2020 19:22:55
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1415 forum posts
147 photos

The grey is light aircraft grey, a standard RAF paint colour. You can order the exact right colour from a paint supplier who offers paint to the BS381C spec. the colour to ask for is 627 Light Aircraft Grey.

Devon Slopes26/11/2020 09:23:58
67 forum posts
43 photos

Brilliant! Thank-you Alan, googling that spec gets to some useful sites.

Devon Slopes10/01/2021 19:43:32
67 forum posts
43 photos

Vacuum Forming?

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Folks familiar with the Andy Blackburn Canberra will know that creating the engine nacelles involves shaping balsa sheets into compound curves (see Andy's thread on this). Having got the balsa wet, I formed the main curve by letting it dry around the vacuum cleaner pipe (hence my claim that it's vac-forming....). More seriously this was version 1 one of doing this. I found you get more curvature if you use tape as well as elastic bands, and run your fingernail along the back to pre-curve it.

Andy also describes how to make a template to get the shape right. I found that if you trace around the bottom of the keels onto a piece of paper (before you glue them on) you get a good first approximation for the edge which joins the wing.

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