Topic: English Electric Canberra B(I)8

Now that I've returned from my little world tour of GB and the Meteor awaiting some retracts to make any meaningful progress I thought I'd start work on the Canberra. It's 84" span, 84" long and has 12sq.ft of wing area  . The original by Chris Golds weighed 18lbs using NiMH batteries and Hacker B16L-50 motors driving Wemotec 90mm Midifans.

I started this a while back cutting by hand but made a few very ill-thought out changes then abandoned it, instead opting to just build it as-is for quickness and using laser cut parts.

The laser cut short kit came from Key Publishing's online shop. Key Publishing have bought out Model Activity Press who published the plan originally and the model featured in a 2005 edition of Flying Scale Models.

Here goes 

The kit comes with laser cut jigs for building the wing centre section. This is probably an easier way of building a wing like this than the way I opted to build the Meteor wing, which was to stand it on the main spar and build upwards - but I'm lazy and can't be bothered making jigs, so this is a nice inclusion in the kit. The spars are both laminations of 1/8" liteply / 1/32" birch ply / 1/8" liteply. These took forever to cut out by hand first time round, and were the single biggest motivation in going laser this time round. If I ever design a Canberra myself I'll make it a monospar for layout reasons which will become apparent later.



Unfortunately Chris made a minor error in the rib drawings which has been reproduced in the kit parts. In summary, the ribs are 2mm too long between the spars. As it happens, the ribs are also slightly too deep at the rear spar, so a simple cut with the razor saw more or less sorts it.
Here are the ribs in place, but only held in by friction at the moment.



Like many models, you really need to know what retracts you're going to use before you start. The plans don't really show what needs to happen to the ribs here, but it's not hard to work out what to do but it's important to sort this out before gluing them in. TBH it may have been better to leave them without the lightening holes, but it doesn't matter too much. It would just have been neater.





Having worked out how high up the retract bearers need to go and cut the ribs accordingly, it was time to glue it all together in the jig.



Chris builds very light and also flies from a hard surface at RAF Chivenor. I by contrast tend to build in the middle of the weight ranges others achieve, but fly from grass usually so I've opted to add in some 1/2" triangular stock just to beef it all up a bit.



That's all for tonight. Hope it's of interest to some people 

Nice one Jamie, sounds like it will be quite a beast 

Cool, subscribed 

This morning I got back to work. Again more fettling was required but nothing worth throwing toys out of the pram about.

I've continued fitting parts of ribs and then moved onto the fan bearers which are cut from hardwood. I should have bought some anchor nuts and Allen key bolts for the retracts and for the outer wing panels. The plans prescribe self tapping screws into the wood which I'd be ok using for the retracts but I'd rather have something a little harder wearing for the outer wing panels which will come on and off each visit to the flying field.



And again with the fans trial fitted to check the spacing of the bearers - more fettling was required. The laser cut bits are nice but it hasn't removed the need for basic measuring and cutting/trimming skills. It's still probably faster overall though...



Being my first build from a laser cut short kit, I think my only gripe is that it's not obvious what's been included. Some things are patently obvious, such as wing ribs, but there are loads of strippy looking bits which might be one of a hundred things and they're not named so it's a case of unfolding 4 large sheets of plan to identify what's there. That's proving a lot slower than my old fashioned method of just cutting these parts out from sheet as I need them.

It's definately slower once having emptied the contents of the box one can confirm that the parts one seeks are not actually there...

I'd rather hoped to avoid cutting my own bits out quite so soon but hey ho. The crutches for the nacelles aren't in my kit and as they're clearly shown on the plan I reckon they could go into future kits. I've still got to cut out the vertical equivalents, but here are the horizontals, from 3/8" balsa. The verticals are 1/4".

That is a real bummer Jamie: pity you live so far away, have done some stuff for Pat but he is only an hour and a bit up the road.  I can guess that they traced the plan, including any slight inaccuracies (hence the additional fitting required), then went straight to cutting - no checking and no beta build to bowl out things like missing essentials.  Never mind, it is still going to be a stunner! 

It would be great to live near someone with a similar interest Pete, that's for sure!

This morning I cut the vertical members, but discovered that the side elevation of the nacelle was about 1/2" longer than the plan view, so I went with the plan view version as everything else was built to suit that.

Here's how it looks now.



I need to do some soldery flappy linkagy faff next to complete the trailing edge, then I think it's on to the outer spars and sheeting.

Jamie,
Your struggles with short kit is noted.  I feel cutting my own maybe slower but I get it in my hands as I move along. Unacceptable that the pieces are not identifiable out of the box.  Also some drawings, if sent to the cutter contain mistakes and will require cutting anyway.  But it seems from what you say that it is worth doing a short kit.
Albert

Hi Albert,

I think if the plan in question was either CAD drawn in the first place or is at least known to be very accurately hand drawn then it would be much quicker. There's absolutely no doubt those spars saved me a lot of time. They took a couple of hours each to cut out by hand first time round and it's very difficult to get them accurate with a scroll saw so you have to cut out "roughly" to within a millimeter or so of the final dimensions then finish with sanding blocks etc - very time consuming.

This plan is by a man who has experience in own-designs that I doubt many people can match for quantity, and he is truely old-school in his methods and will just fix things without really noticing. The plans are probably a bit rougher than many new builders would like, but then again this is an 84" span twin jet model and Chris has probably assumed a basic level of competence of anyone taking this on.

Absolutely nothing I've come across yet has been an issue that couldn't be fixed with a single saw cut, other than the missing crutch parts which required a few saw cuts and a few scalpel cuts.

The kit is cut by a third party not associated with Chris. I'm merely pointing out little things as I find them incase anyone else reading this fancies a Canberra. By noting these little issues others could take them in their stride without worry.

Incidently, I have the only spare canopy and nose glazing vacuum forms that Chris had made. The plugs no longer exist as far as we're both aware. I feel I shoul maybe cast these rather than simply cut them up, as the lack of commercially available canopies may be an offput to some who may otherwise be tempted by a model like this.

What do the viewers think? 

Hi Jamie,
I've just spotted this build - what a great subject too.  The odd mis-match and omission is pretty standard, with laser-cut parts based on a manually drafted plan - and possibly without a check-build? Are the vendors asking for feedback and  interested in improving the offering?  Re-creating the vac-form tools will be a service to future builders - as long as they know where to find them!
Paul W. 

Hi Jamie,
I've just spotted this build - what a great subject too.  The odd mis-match and omission is pretty standard, with laser-cut parts based on a manually drafted plan - and possibly without a check-build? Are the vendors asking for feedback and  interested in improving the offering?  Re-creating the vac-form tools will be a service to future builders - as long as they know where to find them!
Paul W.

I think the kit is cut by Belair for sale by Key Publishing. I guess what would be needed is a back-drafted plan to correct it though? I'll maybe ask Key Publishing if they're particularly interested in corrections. 

Morning Jamie,
I wonder what the response will be - they ought to be keen to de-bug the plan and kit, ideally...  Meanwhile, good luck with another annular spar aeroplane! 
Paul W.

Hello Jamie,
I start my new job today so I may not be around as much...thank God all of you must say.  I am a trained cad guy.    I always wanted to draw my own plans.  That would be the logical progression for me.  Something simple like the Japan's Zero at 80" or about or something that somebody thinks would be a good first.  I want to draw plans but Auto cad is really not what I think is state of the art.  Does anybody have any ideas on a good software for drawing that the commands are similar to AutoCad 20011 ?   Also something that could translate a pdf or pictures into 2 d cad files would really be the way to go.  Something like the full blown Correll software package.  I would get Correll but it is a big investment more the 10,000 dollars and 5,000 for the lite version that does the miracle of producing drawing by scanning pdf files...amazing.   I guess the price tag would be nothing if somebody had a market for them???   One would not need to buy printers or plotters as most blueprint places plot my scanned drawings for peanuts.  Does anyone know where one can get the type of software like Correll?   Not stolen of course.  The amazing thing about Correll is that once you translate it you can send it directly to a CNC laser cutter and do your own kit productions.  Lasers cutters for the size we need for giant warbirds or even 90 scale planes is very expensive 20,000 dollars.  Food for thought.
Parliment is grilling the newspaper tychoon...yum grilled Murdock.
take care,
Albert

Hi Albert. Good luck in the new job. I work for an engineering company and am surrounded by guys using both 2D and 3D CAD systems. Unfortunately I work in project management and my only CAD training was on R14 over 12 years ago. I've tried to get to grips with 2007 but I lack the patience and want results too quickly. I would prefer to draw in CAD but I'm just so sloooooowwwwww at it.

I did begin drawing an Ilyushin IL28 "Beagle" in CAD at around 85" span but only got as far as the nacelles. I can't remember how to use Layers properly.

I would be interested in back drafting the Meteor plan in CAD, and also adapt them for the later night fighter noses and longer wings. Also I'd like to design a true scale Canberra some time.

For a good first time design, I'd suggest the Nakajima B5N "Kate". It's proportions are quite good for a model, and it has a huge wing area. The wings are quite thick and the undercarriage retraction geometry is both very simple and well suited to commerically available retracts. It's something else I did quite a bit of pencil/paper drawing on and is sat half-done in the loft.

Jamie,
Looked up Kate on the internet and really think it fits the bill.  I like it as it is a little obscure and has that "Japanese" design thing going on.  Nice wing transition to fuselage.  Cowl looks like something I could develop in balsa. Yes,  wing area is even noticeable by inspection.  Simple strait forward.  The big canopy has to be an advantage if anything for the new drawer of big scale.  I think if I did it I would make it large...say 1:5 ratio or 20%'er.  Now I have to get the spirit in me to commit as it may take a two years of a little here a little there drawing and much more time in research.  Maybe when I can build a couple more war birds of that period I will take on the drawing challenge.  I really am getting into the BT Spitfire at 80+ inches.  The wings of the Spitfire are tricky and will challenge me in that they seem to be gulled with compound flaps...a challenge for my next build next year. There are a lot of good build thread as this is a popular build. Now I must stay focused on finishing and painting the P-47.  That Corell software is pricey but it can actually scan real construction drawing and translate it from PDF to a ACAD drawing.  Yes ACAD requires practice that leads to memorization and quickness. Layers are usefull and have been made easier by the software guys and you may find it easier if you could get practice at a night school class.
take care,
Albert

The Canberra hasn't been touched in a while due to work, child and general lack of motivation for personal pursuits.

Having finished the P-38 though, and the woodwork (the bit I actually enjoy) being completed on the Meteor, it was time to dust off the Canberra again.

Not much progress - just the lamination of the outer wingspars, but hey, it's one little job crossed off the list 

I had stopped because I needed a supply of anchor nuts and bolts. I have them now. Fittingly, I'm very low on CA, so the spars were laminated with aliphatic glue with CA tacks in strategic places so they wouldn't move when I parked a sodding great weight on top of them to dry. 

My intention for this was and remains to build it pretty much as-is without worrying too much about deviations from scale. One thing which I think will really irritate me if not addressed is the aileron and outer flap hinge line, which I think is really prominent on the real one. It wouldn't be any great feat of engineering to just alter the ribs while they're still in their carrier sheets (i.e. CA the laser cut lines for the plans hinge spars and cut new ones where I want them.



What do y'all think? I'll probably just do it anyway. I need to clear some space on the bench (i.e. tidy up  ) and stock up on CA and 1/16" balsa before I can assemble the outer wing panels and set the dihedral. I hope to make some progress in between Meteor canopy work and imminent baby arrival.  Got 3 weeks paternity leave due so hope to spend my off-shift time unwinding with woodwork 

I'd go for it............as you say, a fairly easy mod and if it irritates you now, just wait until you start finishing it in your chosen scheme.

Nice looking build by the way...I have a soft spot for Canberras, first live jets I ever worked on...231 OCU, RAF Marham, 1980....happy days....

You'd regret it if you didn't do the mod, especially now you've mentioned it on here!!

Ian.

Sold 

Time for some choppy choppy...

Well I went to modify the ribs this afternoon, but as soon as I laid them on the penciled up plan alarm bells rang.

I used to get told I was arrogant by my parents when I was a kid, because I used to be overly critical of others. Yet again though, I feel that I rightly deserve a place above average in humanity. I drew up that Meteor initially intending to publish the plan, but decided just to build it for me on the basis that the plans probably weren't good enough for public consumption. They're a damn sight better than these though. At least my parts drawings match each other.

The ribs as supplied match the rib drawings on the plan, which as far as I can gather are for some other model - definately not the Canberra wings drawn on another sheet of the plan. They're not out by a "little bit" either.

I don't know whether it's original drafting or whether it's the scanning/replication process, but I reckon Mr Bean could have produced more accurate drawings using his "hold your index fingers this far apart" measuring technique.

It's a big expensive box of scrap balsa. 

Why is it so difficult for other people just to get things right? If they worked for me they'd be bouncing out the door on their backsides 

Does it look like the two plans have been printed at different scales, Jamie?

Arsey Enema have been doing this a lot lately - older plans were scanned so that they could be printed directly and needed less storage space. But they seem to have no control over the scaling between scan and print, with random stretchings (perhaps to fill a sheet). It sounds like a basic operator competence issue, but someone needs to sue them for the costs of the errors to "encourage" them to get it right...

If this is the case I'd contact them and demand that they provide both a new (correct) print of the plan and a new kit of laser cut parts. If they decline I'd suggest a small-claims action (moneyclaim on-line) might change their minds.

PDR

I mentioned inaccuracies on plans the other day on another thread and it didn't seem to be well received but it's rearing it's head again by the looks of it.

It's hard to tell Pete, but there are some clues in there such as timbers labelled as 1/4" square actually measuring out about 3/16" on one plan but 1/4" elsewhere. Overall the errors are too inconsistent I think to be a simple case of that. Each of the ribs has slightly different spacings of the (parallel) spars for example, but they all match the appropriate rib drawings well enough. The ribs are all stacked vertically on one drawing, so I don't think a scaling error or even paper stretching could cause all of this.

As the same vendor sells both the plans and the kits though, I'm going to have a proper moan anyway. Even if it was Chris Golds himself who drew the errors (but I'd have thought he'd have spotted this since he did actually build the model from his own plans, and I know he does at least some backdrafting during/after the build before publishing), they should be doing QC checks. If it was just a plan then you could shrug your shoulders, but the kit isn't cheap, and even to scrap the ribs and cut my own would mean a lot of balsa sheet given the chord of this wing.

I've done some careful measuring, and it seems that by trimming that 3mm or so off the centre section ribs as I described earlier in the thread to make the centre section match the plan, I have unknowingly spaced the centre section spars at pretty much the correct distance to suit most of the outer panel ribs (to within shimming tolerances). It's just the actual outer wing panel plans that are useless. The leading edges don't line up with the plan by up to 4~5mm (variable) so if I get the root and tip ribs right to match the sweep I need, I can throw the plans away and just space the other ribs to make the leading edges line up. The trailing edges are mostly wrong too, but to a lesser degree. It'll make changing the flap and aileron hingelines almost a neccessity though, because the supplied cutouts for the hinge spars will be wavy once everything else is sorted. I just need to establish to what extent the pre-cut weakening holes infringe on the new hinge spar location.

Here are two piccies showing the ribs matching up to the rib drawings, and how they compare to the actual wing plan:

If you guys are still interested in CAD then I can point you to a very good freebie that is fully AutoCad compatible and runs on Mac, Windows and Linux; I use Draftsight for anything I have to do in 2D, I really prefer 3D (Solidworks) but still find it usefull to have the 2D option at times (mainly for providing suitable data for manufacture).
http://www.3ds.com/products/draftsight/download-draftsight/

Thanks for that 

Might still be able to use these ribs. The spars needed 2 slots moved and 2 slots widened. The former was because I moved two ribs inboard about 1/4" to make them line up with the leading and trailing edges. The latter are due to CAD tracing errors. The kit cutter used the wrong slot size for the root rib which is thicker, and used the wrong timber thickness for rib R12 (second from tip) using 1/8" instead of 3/32" as per the plans. Incidently the plans call for 1/8" on the tip rib, which are incorrectly labelled as R12 again on the plan but correctly labelled as R13 on the parts, yet they're supplied in 3/32". I can't get excited about that though.

It's one of the real advantages of working 3D, you can put the parts together and make sure everything fits together, with laser cut parts I can supply a file that can go straight in to the machines post processor and get very tight tolerances to my CAD model, I work mainly in sheet metal but how I work could be applied to what we are doing. I have started to transfer a freebie plan onto 3D Cad to see what it would be like, problem is I am used to seeing dimensions not working from a "to scale" print - printing is quite often not very accurate so this explains some of the problems with fit of parts.
Having seen a model designed on 3D cad and followed the cnc laser route and fitting together perfectly (like a jigsaw) I can thoroughly recommend that route - the only problem is that 3D cad with suitable functionality is expensive, there are a few cheap/freebies about but they don't cut it!

Sheet metal huh? My fullsize has brackets to hold the wings on made from 4130 steel 1/8" (0.125in) thick which have some corrosion. Could you cut new ones? I really can't face hacksawing and filing steel. Aluminium is slow and boring enough!

3D modelling is a skill I'd like to have but I just lack the inclination to learn, and seeing it done at work, it's a painfully slow process that I don't think I've got the patience for.

I've only had very elementary drafting training during first year at university, and even that was well over a decade ago. Even still, I can draw parts by hand which fit together. It's just a case of thinking things through and cross checking dimensions against one another.

Lots of mass produced aeroplanes, cars etc were successfully drafted by hand long before people started using 3D CAD to make up for lack of ability to visualise 3D objects from 2D drawings. The oil platforms I'm used to working with are the most complex objects I've ever been exposed to, and most of them in the North Sea were hand drafted, or at very least 2D CAD drafted using the old radar screen style facilities, but even that had to be visualised in the mind and the CAD element didn't offer any design assistance over hand drafting with pens or pencils.
I can completely see the value of CAD, both 2D and 3D but there's still absolutely no excuse for poor drafting using pencil and paper. Without meaning to blow my own trumpet, the Meteor was sketched rather than properly drafted using pencil, steel rule and set square on wall paper. From memory there were 3 parts which didn't fit properly first time, and that was just because I was stupid. If I, an impatient buffoon, can do it, anyone can - or at least should if they're going to charge money for copies of it!

Last one for tonight - tomorrow I'll be back onto the Meteor canopy which has been worked on sporadically tonight...

I framed up t'other wing this morning and put it all together for an impression of size. The chord is still 3" short as the flaps and ailerons are missing. The tips are worth another 2" span each side. It'll take quite a lot of balsa and glass cloth and resin to skin all of this 



The plywood outer spars which attach the outer wing panels to the inners aren't glued in yet, and whilst obviously close enough to do this pose, the fit needs some fettling to be good enough for day-to-day use. It's nothing that can't be fixed though. Next I'll need to make new hinge spars and fit leading edges.

Wow that's bigger than I expected  (said the actress to the bishop  )

I always believe size wasn't important.

But then all my wallpaper fell off.

PDR
(with acknowledgement to the late and much missed Humphry Littleton)

(with acknowledgement to the late and much missed Humphry Littleton)

It's Lyttleton with a Y    I didn't think you made mistakes, PDR 

Looks good mate, good luck with the rest of the build; by the way just out of interest what are you going to use for propulsion?

Hehe 

I haven't got any more done. Dear wife wanted to go for a walk to try to shake out Baby #2 who is now 4 days behind schedule. I know which side of the family this one takes after already 

I've also been given a challenge to find my mate an automatic car for under a grand which is better/more interesting than the Vauxhall Astra he's otherwise going to buy. Since baby doesn't appear to be coming today, I'd best get some shirts ironed too 

by the way just out of interest what are you going to use for propulsion?

Big Mahoosive hands.

Forgot to answer the question 

It's going to be twin Wemotec 90mm Midi fans with a pair of 36mm long can inrunners, probably on 8S LiPo.

A reckon Wren 44s would fit in, but spending £3000 on engines for a toy plane doesn't align with my priorities. I think it would work though.

Hmm, understand that completely Turbines are mega expensive but you will probably see respectable performace any way, I don't think that having a mega rapid model is what it's all about!

I think it should be quite sporty.

Chris Golds' original weighed 18lbs and was powered by Hacker B50-16Ls on, if memory serves, 16 C-size NiCds/NiMHs. He said it gave a thrust/weight ratio of 0.45:1 and performed well. This was a decade ago though.

I think that my model will weigh about the same - going heavier duty on servos, retracts etc, but won't be carrying around half a tonne of batteries. In addition, I expect between 12~15lbs of thrust. The Midi fan can produce up to 10lbs when thrashed with really hot motors, but mine will be a bit softer than that. Even still, I expect a strong performance, and it should be able to emulate the sort of manouvers that the big engined PR.9s used to at airshows with ease.

It's got more wing area than you can shake a big stick at, so it'll carry whatever weight it's asked to. It's really just a question of how steep do you want it to climb?