Andy Meade Posted January 11, 2016 Share Posted January 11, 2016 Here we are then, another large PSS build. I had drawn up a large AC130 gunship for PSS a couple of years ago, but didn't as far as 3D CAD - just a few sizing sketches over some 3-views, but then someone else decided to make one! Thus, the C17 idea was born. I watched those Discovery Channel episodes 10 or so years ago where they built one quickly, all in balsa with some mouldings here and there, for 4x turbine power. What a beast! So the C17 (or BGC - Big Grey Cloud) idea was niggling away at the back of my head, and with a build board full of other airframes requiring attention or finishing, it's obviously the ideal time to start something new and big! I started off with a quick internet search, and found a 60" C17 plan for depron, as a free plan. A good starting point, as the formers were all reasonably well shaped (apart from the undercarriage area), so I grabbed that, imported it into SolidWorks, and started work. Firstly - what size? Well, the BGC is a big aircraft, and 60" would give something not very imposing in the air, and it would probably get bumped around a lot. Bigger then. I had always planned the AC130 to have a 400mm round fuselage, so this is where I started, giving me a 3.4m / 133" span. Sketches were resized, some formers re-worked, and structure added to make this a two part fuselage, plug-in wings, and a removable tailplane. The plan so far is to make the fuselage out of 4mm (cheap!) ply - a crutch with formers and a couple of (pine) stringers to keep everything square. This will then be blocked out in white foam, covered in brown paper & PVA, then probably glassed. The wings, tailplane, and fin will be white foam, cut and veneered by me. Finish will probably be silver film straight on, then the whole model primed and sprayed. The engines will be 3D printed in 3 pieces, sanded and primed to match, and will have some facility to be knocked-off in long grass. I intend to re-create the huge blown (but not blown) flaps from the full size, along with top-surface spoilerons / brakes. I will firstly use them as brakes when full flap is selected, but might also mix them to go up with the up-going aileron. The rest of the controls will be rudder, elevator (2 servos), and some scale lighting too I hope. Overall fus structure : Big(ish) : Oh, and did I mention there will be two? I will get the first build moving quickly, then provide a kit of parts for Dave Gilder to create one too. I want this flying this year, thus the "quick" construction and finishing method. Onwards! Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 Here is the plot of the side-view of the fuselage, along side my Futaba 10c : That'll do. Last night I started sticking former templates to wood - I should have the first formers complete this week. Oh, I should also add - Dave is making his fin removable for transport, but as this will go into my trailer or camper van without too much hassle, mine will be one piece back there. The fuselage splits behind the TE of the wing - where pink changes to purple on the crutches in the above images. Quote Link to comment Share on other sites More sharing options...
David Gilder Posted January 11, 2016 Share Posted January 11, 2016 Looking Good there Andy. Cant wait to see yours started and knowing there will be parts heading my way shortly after for me to get started. I'm hoping to learn a lot about building big from you through this and the A10 build but will no doubt have lots of questions once underway!! (Like where is best to get the steel wing bar!) Signed up and eager to get building myself!! Dave Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted January 11, 2016 Share Posted January 11, 2016 Nice Andy, how exciting. Will you have to remove the landing wall to build the fin in 'situ' on the plan? No joking aside keep up the good work. Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 Dave - if you have a "Homebase" nearby, go in and buy a 25mm square length of steel. Wall thickness is about 2.5 - 3mm if memory serves, and get the long one. 5 foot is all you need, but I think they do a 4 foot one. A cheap and wayyyy over-specced wing joiner - A10 technology carried over Mark - thanks! Hopefully will have this done for Lleyn, but we will see. Edited By Andy Meade on 11/01/2016 12:17:34 Quote Link to comment Share on other sites More sharing options...
Matt Jones Posted January 11, 2016 Share Posted January 11, 2016 Subscribed! BTW, what's going on with that guy's thigh? Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 I have no idea I got a standard model from GrabCAD, and for some reason one thigh went a bit odd. I was too lazy to fix it I'm afraid Quote Link to comment Share on other sites More sharing options...
David Gilder Posted January 11, 2016 Share Posted January 11, 2016 Posted by Andy Meade on 11/01/2016 12:16:49: Dave - if you have a "Homebase" nearby, go in and buy a 25mm square length of steel. Wall thickness is about 2.5 - 3mm if memory serves, and get the long one. 5 foot is all you need, but I think they do a 4 foot one. If I need 5ft and they do 4ft that leaves me a ft short!!! I suspect flappy wing syndrome if this is the case!!! Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 Sorry, I should have said they do a 4 foot and a 6 foot. Get the 6 foot, cos all you need is 5. Let me double check that actually. Quote Link to comment Share on other sites More sharing options...
David Gilder Posted January 11, 2016 Share Posted January 11, 2016 Beginning to be scared now..... If this is how you measure things!! Maybe I should wait for the plans and measure it myself!!! lol 5ft sounds about right for the 11ft wingspan! Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 I've sized up the wing boxes, just not actually measured anything in the model. The limiting factor is the monster anhedral the wing uses. It's 5 foot. Edited By Andy Meade on 11/01/2016 13:19:48 Quote Link to comment Share on other sites More sharing options...
David Gilder Posted January 11, 2016 Share Posted January 11, 2016 Cool. I will get it on the order list!!! Nothing to stop me cracking on with a relatively quick build when the parts arrive then! Quote Link to comment Share on other sites More sharing options...
Flyer Posted January 11, 2016 Share Posted January 11, 2016 Very nice Andy. Will follow this with interest. It will dwarf the AC130 ......... a mere 2.7m . As a matter of interest, would a built up and glassed wing be much lighter than foam veneered? (Looking at doing that myself). keep up the good work Ade Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 Hi Ade, I'd imagine the built up version to be not only lighter but stronger too. My main reason for going with a foam wing is that my built up wings are an embarrassment when it comes to straightness, and I can knock out a completed foam wing pretty quickly. I really want to see the C17 and AC130 flying a tight formation on the slope! Quote Link to comment Share on other sites More sharing options...
Flyer Posted January 11, 2016 Share Posted January 11, 2016 Posted by Andy Meade on 11/01/2016 13:37:31: I really want to see the C17 and AC130 flying a tight formation on the slope! I'm not too sure that I can build a straight wing that big yet !!! , but I've a better chance that a foam wing. You may have to wait until next year to 'hopefully' see the C17 and AC130 fly together, as I will not be able to get on with the construction plans until February, due to work, but you never know. Do you hollow the white foam infill blocks on the fuselage? Cheers Ade Quote Link to comment Share on other sites More sharing options...
Matt Jones Posted January 11, 2016 Share Posted January 11, 2016 Andy, built up wings are easy at this size, 1/8" - 1/4" ribs and 3/32" sheeting, it goes on much easier than the usual 1/16". Dave, if you want to save weight I'd make the wing three piece with the dihedral build into the centre section, the joiners to the outer panels could then be short lengths or carbon tube, say in the region of 25-35mm dia rather than 5' of box steel. Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 Yes, where possible I will use a hot-wire to leave about a 2" wall on the fuselage. The rigidity should be supplied by the crutches and formers. That's a good idea Matt - certainly possible. The centre section could then bolt into the fuselage with the normal large dowels + bolts, or maybe a ply tongue on the front like the Cocker B52. The only problem with that is..where to split? The flaps take up about 85% of the span, and you'd likely want not just plug-in tips. Also storage - with that sweep, it becomes a big lump very quickly. I'll let Dave decide what he wants to do with his Edited By Andy Meade on 11/01/2016 13:46:33 Edited By Andy Meade on 11/01/2016 13:53:37 Quote Link to comment Share on other sites More sharing options...
David Gilder Posted January 11, 2016 Share Posted January 11, 2016 Interesting idea Matt. Yes it would save in weight but with this being a very wide bodied aircraft, going light could lead to penetration issues resulting in a very non scale like flying characteristic! I think the A10 would have had a lot less speed and penetration if it hadn't had the extra weight provided by the steel bar! And to add also, Andy is very kindly cutting me a set of wings so its less to worry about and will aid a speedier build! I will be doing a blog also when I start my build! Quote Link to comment Share on other sites More sharing options...
Phil May Posted January 11, 2016 Share Posted January 11, 2016 Subscribed and following with interest 👍 Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 I can always cut another kit of parts Phil! Quote Link to comment Share on other sites More sharing options...
Monz Posted January 11, 2016 Share Posted January 11, 2016 Look forward to your build Andy! Nice to see so much PSS activity about Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 11, 2016 Author Share Posted January 11, 2016 Thanks Monz! I'd love to try one in depron at some point Quote Link to comment Share on other sites More sharing options...
Phil Cooke Posted January 11, 2016 Share Posted January 11, 2016 Subscribed Andy - look forward to seeing you and Dave develop these heavies from your conceptual drawings to slope. I can't imagine how little spare room you have in your workshop starting this with all the other projects you have on the go - you are an inspiration to us all!! Quote Link to comment Share on other sites More sharing options...
David Gilder Posted January 11, 2016 Share Posted January 11, 2016 Well I have tidied my workshop up the other day Phil in readiness. It currently has the AN72 on the desks which I hope to have nearly ready by the time the BGC parts arrive!! Now as I understand things, Andy is doing a standard military grey for his colour scheme... I on the other hand want to do something a little different (as always)... and so I will be looking to complete mine in the colour scheme adorned on A7-MAB! Hopefully this will also aid us in telling them apart in the air!! Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted January 11, 2016 Share Posted January 11, 2016 Andy, Great subject choice and the CAD images really make the project come alive - will follow with interest - subscribed. Harry 1 Quote Link to comment Share on other sites More sharing options...
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