Bob Cotsford Posted October 9, 2012 Share Posted October 9, 2012 I'm working - i must be as nothing is going wrong at the moment. IT Support is a great life - right up until the phone goes at 2:30 am. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 9, 2012 Author Share Posted October 9, 2012 I am on one of those Exchange 2010 faults right now... (: M Quote Link to comment Share on other sites More sharing options...
Chris Poulton Posted October 9, 2012 Share Posted October 9, 2012 Do the ply doublers go to the nose ring Martyn? If not, then butt-joining the firewall to the fuselage sides (chamfering the sides of the firewall to ensure maximum contact area) using a good epoxy, and either adding triangular strip, or surgical gauze / fibreglass bandage and epoxy should be plenty I would think. If the ply doubler goes right up to the nose ring, the triangular stock or fibreglass / epoxy could be either side of the firewall. There are other things I would lose sleep over, but not this Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 9, 2012 Author Share Posted October 9, 2012 Hi Chris The ply doublers go just past the firewall - could be extended by a few more mm but not much further as the 40mm or so around the engine gets very curvy. I am planning to put triangle stock either side of the engine mount at the front plus a big piece under the tank floor to firewall joint plus another log between the top of the Firewall and under the cockpit floor. I think that if I split the cockpit floor about 25mm back from the Firewall that will give enough strength and an access hatch to slide the tank out. The SLEC tank is nice for this as the top of the tank is raked back at the front so I can get a decent sized piece of wood in there My other headache is finding space for a steerable (fixed) noseleg and getting the steering linkage to it. Aprt from that, it is all very straightforward. Martyn Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 9, 2012 Share Posted October 9, 2012 re steerable nosewheel: Some time back I bought a Marabu off e-bay, and when I collected it I somehow ended up with a bag of bits for 40 size models. At a guess these were dated from some time in the 80s, as the engine mounts are too tight for a modern BB 40 crankcase. One of these consisted of a near complete fuselage, tail and veneered wing halves for a non-descript low wing model. I got bored last week and started putting it together. I really can't see how to get a steerable nosewheel on this size of model without the linkage hanging out of the bottom. The radial mount gets in the way. So I didn't, I'm just leaving it fixed. I had a Pilot Commanche with fixed steering, it would actually steer by giving full up and some power to unload the nosewheel, so don't sweat it. Ps - I'm a dinosaur - strictly MVS mainframe - COBOL, IMS, DB2 - all the stuff they told us was dead or dying 20 years ago. Unfortunately it means all the important stuff runs overnight. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 9, 2012 Author Share Posted October 9, 2012 Hi Bob Unfortunately, the version of Profili that I use doesn't support export to DXF. The pro version does but that means parting with beer tokens to pay for an upgrade and at the moment I am a bit skint.. Anyone else reading this has the pro version of profili XT that can do the coversion for me...? Otherwise, I'll see if there are other ways of getting the files converted. Martyn Quote Link to comment Share on other sites More sharing options...
Robin Kearney Posted October 9, 2012 Share Posted October 9, 2012 Martyn, I have the pro version, happy to help with the conversion. I'll pm you an email address. r. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 9, 2012 Author Share Posted October 9, 2012 Thanks Robin Do you have any tips for laying out the ribs for laser cutting.Belair seem to suggest that it is up to the designer to define the layout - this is a new area for me.. Are their resrictions on width or length that I need to be aware of? Regards Martyn Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 10, 2012 Share Posted October 10, 2012 a little inspiration for anyone thinking of fitting retracts - from RCG - check out the tank and retract installation photos Edited By Bob Cotsford on 10/10/2012 12:24:36 Quote Link to comment Share on other sites More sharing options...
Robin Kearney Posted October 10, 2012 Share Posted October 10, 2012 Hi Martyn, I'm afraid I've only printed airfoils out onto paper, so I have not laser/cnc experience. I assume you would have to find out the minimum gap so the tool doesn't crash into the next part, aside from that I guess as close as possible to avoid wastage, and maybe little tabs to keep it all together. Not particularly helpful now I've read it back, sorry! Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 10, 2012 Author Share Posted October 10, 2012 Hi Robin Thanks for the info.I'll drop Belair a note asking how wide the wood is etc.I preume it will be 100 or 150mm wide. Also need to orientate the wing ribs and formers so that the grain is running in the right direction. When I understand what I need to do, I'll email you the profili file. Best wishes Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 10, 2012 Author Share Posted October 10, 2012 Here is the plan. Hopefully, it will print correctly on 1 sheet of A0, but before you get too enthusiastic, print off a section of tailplane with all the dimensions labelled to manually check X and Y dimensions. Curare 25 Plan Comments/critisisms welcomed. I have checked the rib sheets (above) and they all appear to be the correct size Good luck. If you do choose to build it, please run a blog here so I can see how you get on. Happy to answer any questions if things arn't totally clear. Probably lots of those... PS - haven't heard from Hanno yet so not sure if I got the right one. Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 11, 2012 Author Share Posted October 11, 2012 Dont print the A0 plan just yet. The PDF printing seems to have shrunk it by about 16% - I think I know what went wrong. I so wish I had a proper plotter. It may need to go onto 2 sheets.. Martyn Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 11, 2012 Share Posted October 11, 2012 I saw an ad for GAD offering laser cutting at £3.50 for a 4*36 sheet. I'll see if I can find it again. here it is Edited By Bob Cotsford on 11/10/2012 10:39:25 Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 11, 2012 Author Share Posted October 11, 2012 Yes please.... M Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 11, 2012 Share Posted October 11, 2012 If you send the file to get a quote, ask if they would do a group buy discount Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 11, 2012 Author Share Posted October 11, 2012 Plan has now been resized - the problem was that it was trying to fit onto A0 which wasn't big enough.. Redrawn onto 2A0 sized paper which is now too big. Ideally, 50"x40" will suffice. I will do a version at this size which may be OK for tile printing if required. If you have already downloaded, please download again using the same link as above. Regards Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 11, 2012 Author Share Posted October 11, 2012 Posted by Bob Cotsford on 11/10/2012 10:37:28: I saw an ad for GAD offering laser cutting at £3.50 for a 4*36 sheet. I'll see if I can find it again. here it is Edited By Bob Cotsford on 11/10/2012 10:39:25 Thanks I have just e-mailed them requesting info on layout wood quality etc. Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 11, 2012 Author Share Posted October 11, 2012 Posted by Bob Cotsford on 11/10/2012 10:41:09: If you send the file to get a quote, ask if they would do a group buy discount Will do. Martyn Quote Link to comment Share on other sites More sharing options...
Robin Kearney Posted October 11, 2012 Share Posted October 11, 2012 Bob, that price from GAD strikes me as a bargain! I wonder if we could petition RCM&E to offer a DXF of the parts of each plan so we can get the wood cut in cases where they don't offer a wood pack! r. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 17, 2012 Author Share Posted October 17, 2012 Apologies Been a bit of a delay since the last update. Very busy at work... I have redone the plan again - all the bits now seem to fit on the paper - I hadn't noticed that I had lost a wing tip and root after inadvertently moving the 0,0 reference. Sorry about that. The revised plan is here. It can be printed from the latest version of Adobe reader by selecting the poster option. You will need about 30 sheets of A4 paper although at least 10 will be blank and can be reused. My first attempt took me about 2 hours to assemble and then I spotted the missing bits off the end.. I have also upgraded my version of Profili to the Pro version this week and have now exported the ribs to DXF and I am preparing them for laser cutting. Not quite as straightforward as I imagined as the ribs are generated using a continuous curve rather than segments. This means that it is difficult to trim the leading, trailing edge and spars whilst leaving the build tabs intact. I am also a bit nervous about committing this to a cutter without building a protype first, I am convinced there will be at least one error and my professional credibility as an amateur CAD draughtsman is at stake. . Your comments on how to proceed would be gratefully received. I suppoe it all depends on how much of a rush you are in. Best wishes Martyn Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 18, 2012 Share Posted October 18, 2012 Martyn, for myself I think I'd get the ribs lasered as a start point to see if any issues arise with respect to laser interpretation of the drawings. I dare say if asked the cutters would be happy to provide any hints they may have to ease the process. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted October 18, 2012 Author Share Posted October 18, 2012 Hi Bob Whatr about the plywood parts? The cutter has suggested using 1/16" ply instead of lightply for the root ribs (around the u/c). I was also also going to get the 4 formers cut (3mm ply). Cutter has suggested using 2 lams of 3mm ply to make the Firewall. The other parts I am laying out are the wing dihederal braces (1/16" ply) tail dihederal braces (1/16" and 1/32" ply" and possibly the fuselage doublers (1/32" ply). I have not allowed (at the moment) for the balsa/spruce doublers in the wing and tail roots to ensure that the ply doublers have got something straight to be glued against. The build plan I was going to follow to do this was build the LE and TE with the tapered doublers (and braces) in place, then trim the ribs to fit while located against the lower spar, then add the upper spar, the remaining doublers and the main brace in place when the dihederal has been set. All will be manually inserted and cut at the point of fitting. It is not an easy build, with the added complexity of keeping the eight down. On a positive note, I have got most of the tail ribs ready for cutting. It's taking a while though, I have never done any of this minikitting before, good experience though. Martyn Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 18, 2012 Share Posted October 18, 2012 I've never been a fan of light ply other than for it's ease of cutting for servo mounts and the like. My Skybolt has a bulhead of 2 laminations of 3mm birch ply holding back a 120 four stroke so that idea will work fine for a .25. I'd even be happy using a single 3mm ply as long as it's good quality with suitable triangular fillets to brace it to the sides. Spruce doublers - I assume these are to accomodate the sweepback on LE and spar? One alternative I've seen is to use aluminium dihedral braces bent to follow the sweepback. As for rib alignment (I think that's what 'of keeping the eight down' refers to) I used a jig to build the Altair. All ribs had a pair of 6mm holes on the horizontal centreline and were threaded onto two 6mm carbon rods. The rods were supported at the ends in suitable blocks so the whole wing was built suspended over the plan. Once the spar webs and top sheet were in place the wing was inverted and clamped back in the supporing blocks while the underside was completed, then the rods pulled back out ready to build the other half wing/tail. (this was before clamping up the carbon rods) This might be a bit over the top for the size of model we're talking about here though, so I'd just rely on the rib tabs. Quote Link to comment Share on other sites More sharing options...
IanR Posted October 18, 2012 Share Posted October 18, 2012 Bob, A newbie question - having got the carbon spars so neatly inside the wing, wouldn't it have been an idea to glue them in permanently as extra strengthening? Ian Quote Link to comment Share on other sites More sharing options...
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