Danny Fenton Posted January 2, 2015 Share Posted January 2, 2015 Mmmm I thought that it would have been okay to take almost all the centre of the bulkheads out, much like the lower half of F7. My bulkheads were such soft wood It might not have been wise, but the wood that came in the cut parts was a bit hard/heavy. Not really seen how the others are doing this area..... Cheers Danny Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 2, 2015 Author Share Posted January 2, 2015 My formers are quite soft/light so I was reluctant to take too much wood out. I am rather inclined to use snakes for rudder and elevator and leave the formers in situ without any cutouts. I am not in too much of a rush to make the tail extra light as I think that additional weight at the rear may be required to get the CG correct. Martyn Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted January 2, 2015 Share Posted January 2, 2015 You've moved on quickly Martyn, I left the formers intact for the same reason and used piano wire through nylon tube for pushrods, it's easy to fit them and get a good slop free run. I cut my wing seat as plan but had to recut it as it needed to be deeper. John Quote Link to comment Share on other sites More sharing options...
Nigel Day Posted January 2, 2015 Share Posted January 2, 2015 Really motoring Martyn and looking good. I'm just about to start the fuse and will be using snakes so I'll be following with interest. Quote Link to comment Share on other sites More sharing options...
Nev Posted January 2, 2015 Share Posted January 2, 2015 Cracking on now you‘ve got started Martyn, looking tidy too. Don’t think you need worry about lagan behind. Nev. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted January 2, 2015 Share Posted January 2, 2015 Good stuff Martyn. You might have been wise leaving the wing until later, have a few good stiff scotches before you start on it though! Quote Link to comment Share on other sites More sharing options...
Levanter Posted January 2, 2015 Share Posted January 2, 2015 Like your planking. Good work Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 6, 2015 Author Share Posted January 6, 2015 A bit more planking. Hopefully I am not teaching you to suck eggs, but this is how I do my planking. Each model is different so I have to adapt but the principle remains the same. The lower half was quite easy as I elected to use sheet from the front bulkhead to where the taper really starts behind the cockpit area. The top section is not so simple with two distinct opposing tapers. So, for the top I used quite narrow planks, 8.5mm in the centre, 3mm wide at the tail and sanded to about 7.5mm at the front. As each plank is cut, I also sand a bevel on one edge only - the other side is left square.. I assemble 2 planks at a time, one each side and very gently pull them together with clamps. The pegs hold adjacent planks flush with each other. This way I get a good seal.. You can only use this technique for the first 50% or so using clamps as you get further round the fuselage the clamps start bowing planks inwards - so I just have to reply on the pegs to keep everything straight. Eventually - as the fuselage is still pinned down flat - I can't the pegs in either and have to use pins to hold everything together. When there is about 3 planks remaining to fit, I placed a full width (8mm) plank from the crutch upwards and then fitted the final planks cut to fit - these are really very tight wedges fitted into the remaining gap. Which, you may be able to see in the picture above Its a very slow process planking this way. On a good day, I can get 8 planks fitted (4 each side), the upper fuselage took me 4 days to complete. there are still one or two gaps that need filling.. Not the best photo, but now that the planks have been trimmed on the rear upper former you can see how they have gone together. More to come... I'll cut out the cockpit holes after they have been sanded to fit then I'll start on the modified wing - when I eventually decide on what and how I'm going to do it.. So the tailplane, rudder tail wheel and fin assembly may get done first... Martyn Edited By Martyn K on 06/01/2015 09:09:17 Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 6, 2015 Share Posted January 6, 2015 Very nice work Martyn - coming along well. BEB Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted January 6, 2015 Share Posted January 6, 2015 Nice hull you've got there Martyn. There's something very satisfying about planking compound curves but it is a slow process to get good gap-free fits as you have there. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 6, 2015 Author Share Posted January 6, 2015 Thanks both. I have to admit that I am quite pleased with it (so far!) Quote Link to comment Share on other sites More sharing options...
Nigel Day Posted January 6, 2015 Share Posted January 6, 2015 Nice Martin. It's good to see that someone else built a boat hull too. What glue are you using for the planking? I used cyano for the top half. This allowed me to hold each bit of planking in place whilst it set to the former and close to the previous plank. The problem is that this much cyano fumes isn't good - and get's a bit thumbs down from SWMBO. I'm going to use aliphatic on the bottom with pins to hold it in place. I'll see whether I need pegs and clamps as I go. Thanks for the explanation. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 6, 2015 Author Share Posted January 6, 2015 Thanks Nigel I used to build boats - its much harder using mahogany planking.. I use PVA for (nearly) all wood joints - Evo-Stik Resin W Green. I don't get on with Ali's Phatic and I find Cyano a bit too brittle and temperamental. Epoxy is used occasionally for things like engine mounts where I want to prevent oil ingress. I don't think that Epoxy is that much stronger than PVA if the wood joint is sound but it does help prevent oil damage. Martyn Quote Link to comment Share on other sites More sharing options...
Andy Muckley Posted January 6, 2015 Share Posted January 6, 2015 Nice job Martyn and i agree about the pva if your joints are sound then pva is a very good Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 8, 2015 Author Share Posted January 8, 2015 Moving on. The two halves have been tacked together and with careful sanding and a little filler, it look like this. I use Ronseal wood filler - natural - it fills well, sticks well and is softer than the balsa. Just moisten it regularly to keep it soft. So time to mark out the position of the cockpit. Working from the two formers that define the rear of each cockpit, I transferred the layout from the plan to the upper fuselage.. and and then with heart I mouth I went at it with a Razor saw.. After that, I needed a lie-down.. Still a bit more sanding to do, but that will be done when the fuselage halves are glued up properly More to come. Martyn Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted January 8, 2015 Share Posted January 8, 2015 Nicely done Martin, not familiar with that filler, is it light weight? The stuff i use the tub feels empty, its so light!CheersDanny Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 8, 2015 Author Share Posted January 8, 2015 Hi Danny I don't use a lot of it - for big fills I use epoxy/microballoons but the Ronseal stuff appears to be water based so dries out quite light. It is great for filling in those little gaps in planks. I spade it in using an offcut of spruce then rub it in with my fingers. A light brush over with 240 grit quickly removes any excess. It dries hard in about an hour at room temperature. It doesn't clog the sandpaper either but the dust produced is very fine. I get it from B&Q - it costs about £5 per pot which lasts a long time if you keep it moist. My trick is to spit in it (saliva) after I have used it and then put the polythene seal over the top surface of the filler. M Quote Link to comment Share on other sites More sharing options...
Nigel Day Posted January 8, 2015 Share Posted January 8, 2015 Nice one Martin. I haven't worked out how best to mark and cut my cockpit cut-out yet so I may just follow your lead - with a stiff drink at the ready in case! Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 8, 2015 Author Share Posted January 8, 2015 Cheers Nigel The former positions were located by pushing a pin through and checking that it is touching the former when looking from the inside. The bottom of the cockpit was measured up from the crutch on both sides - measurements taken straight from the plan. I wrapped a piece of card around the fuselage to mark the rear edge of the cockpits - again checking that they were flush against the formers using the pin technique. Draw the line to the intersection with the base. Measure forward from the rear of the cockpit to the forward position (measured off the plan) and mark on the cockpit base and the upper centre line (if you remember, I used a single full width plank for my keel piece so my centre line is easily determined). Using the card wrap around, draw from the top to the bottom and you have your cockpits marked. Good luck Martyn Quote Link to comment Share on other sites More sharing options...
Nigel Day Posted January 8, 2015 Share Posted January 8, 2015 Thanks Martin, very helpful. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 11, 2015 Author Share Posted February 11, 2015 Well - now the STOL is out of the way, I have started thinking a bit more about this. I intend to get as much of the fuselage finished before I start on the wing, but I need to plan for any changes to try and get the flaps and ailerons to the correct scale size. So, last night I attacked the plan with a pencil and ruler and working from 3063, scaled up accordingly. To get the flaps the rights size, I need to extend the wing width (LE to TE - excluding flaps and ailerons) down the entire length - except at the tip - where it is actually correct. This shot shows the crosshatch which is the revised shroud location. It seems easier to work from that as a datum. The Red line shows (approximately_ the outer edge of the upper wing fairings. There are two revised rib locations to get those slanted ribs and the centre sheeting ends at the first slanted rib. The area in front of the main spar in unchanged At the junction between the flap and the aileron The shroud is getting a bit nearer to where it should be. On 3063, the shroud is shown as a straight line but (AFAICS), there should be a 4mm step between the flap and the aileron hinge points Finally at the tip, the shroud is in the right place. So.. to accommodate this and make as much use of the cut parts material as possible. On the root rib, (as an example), I will need to extend the rib back a bit and cut the flap aileron ribs down a bit - the latter is not difficult, just slice a parallel edge off, but the wing rib is a bit more tricky Somehow I need to integrate the existing rear spars and B3/B4 into this revised layout or it wont fit in the fuselage. The spars are not too much of a problem as they sit below the surface of the wing and a cap strip will hide them. The new TE can be a simple sheet strip - say 5mm wide - it will only be carrying the load of the flaps and ailerons so I think that this may be "doable". The bit that bothers me most is integrating that double swoopy under fuselage fairing into this revised wing and whether that will need changing as well. So... do I bother? Martyn Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 11, 2015 Share Posted February 11, 2015 Its great experience Martyn, but do you bother...... that is a tough one, to me there are so many bits that are just wrong on the plan, I wouldn't spend the time and effort, the only person that will really know is you. Having said that, why else would we add all the detail we do, much of it will go unseen, because we enjoy it..... So I am afraid nobody can answer the question but you Cheers Danny Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 11, 2015 Author Share Posted February 11, 2015 The other problem I forgot to mention is that the 2 slanted ribs at the root are in the correct scale location - unfortunately, the others are not. So the gap between R3 (new) and the old R3 is incorrect - which would mean that all the other rib locations would need to be redone. Aesthetically, I may just do the wing but keep parallel ribs as per the DB original. At least, it will look more right Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 12, 2015 Author Share Posted February 12, 2015 Started work on the tailwheel assembly last night. I have found this engineering drawing of the tailwheel assembly. As expected it asks more questions than it answers If you compare this against the measurements taken directly from the DB plan, then this diagram is about 4x larger linearly. I really would try and replicate this at the correct size and if possible make it pivoting/sprung as per the original. I envisage manufacturing the triangular yoke using brass tube (silver soldered) then filled with something light and extending the pivot tube into a block in the base of the fuselage and stop it twisting or moving off centre. That bit, I think should be quite easy. The tricky bit is the wheel fork. It appears to be made from 2 lateral U shaped plates welded to the fork legs. The tube is 4mm diameter- any suggestions on bending thin wall brass tube over this radius The other thing that bothers me is the size of the tailwheel. Scaling this down, it looks like a scale tailwheel should only be 21.5 mm diameter. This image shows a comparison with a dummy wheel of the plan size used for reference. You can see that the wheel on the engineering drawing is definitely not 4x bigger than the DB plan wheel. Any thoughts Maestros? M Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 12, 2015 Share Posted February 12, 2015 Hi Martin, I would love a copy of that drawing if you wouldn't mind, can't quite make out the details from the pic To be honest Martyn, I think you are quite capable of doing a better Chippy than this plan is allowing, how about doing another one further down the road? Everything you have done to date is background info and is food for thought. I have the drawings for Dave Womersley's 1/4 scale Nats winner as well as Jerry bates 1/4 scale version. I think one of those two would be a much better basis for the amount of effort you want to expend. 1/6th scale is such hard work to get the detail and keep the weight down 1/4 or even 1/5th is so much easier to work with. Just my thoughts, you are doing a great job, really impressive Cheers Danny Quote Link to comment Share on other sites More sharing options...
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