Tim Hooper Posted January 4, 2015 Share Posted January 4, 2015 The brief is to create a viable RC model that can be drawn on two A3 sheets of paper. Obviously I have no idea what this design is to be used for. Mine is not to reason why, etc........ Using graph paper I sketched a reduced-size plan to get an idea of the proportions. That done I set about sourcing the hardware, and gained this little lot.... There's a 10 gramme 2000 kv motor, a 4x4 prop, 4 x 3.5 gramme servos, micro rx and 10A ESC. Here's the wing drawn full-size. A massive 22" span! The orange card contains the Profili printouts, using an E207 semi-symmetrical aerofoil. The lower wing skin is from 1/32 balsa. The lower skins, spars and ribs in place - all done with thin CA glue. The tips are raised to give 1/4" dihedral, and then the central joiner tubes are fitted. There's a central 3mm cf rod. Beneath the rod are two protruding 1/32 ply plates which will pass through the fusealge sides. These will be linked with a clip to prevent the wngs coming adrift in flight! The fronts of the lower skins are raised with tapered balsa wedges, prior to fitting the 1/4 leading edges. So far, so good....... Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted January 4, 2015 Share Posted January 4, 2015 Already looks fascinating Tim Quote Link to comment Share on other sites More sharing options...
WolstonFlyer Posted January 4, 2015 Share Posted January 4, 2015 Very interesting, who set you the challenge? Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 4, 2015 Author Share Posted January 4, 2015 Posted by WolstonFlyer on 04/01/2015 21:37:58: Very interesting, who set you the challenge? That must remain a closely guarded secret. Let's just say the edict originated in South Essex...... All the gear weighs in at 96 grammes, leaving around 60 grammes for the airframe. tim Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted January 5, 2015 Share Posted January 5, 2015 happy new year Tim to yourself and your good lady......see you pushing the boundaries again.....well done - look forward to seeing the completed model.... ken Anderson...ne....1..... TH fan club...dept. Quote Link to comment Share on other sites More sharing options...
Vecchio Austriaco Posted January 5, 2015 Share Posted January 5, 2015 Hi and Happy New Year. Looks very interesting. Why do you have 4 servos in your hardware-pot - are you planning to use 2 servos for the ailerons? Looking at the size of the plane the wing will be quite thin I suppose. Are you positioning them in the fuselage? VA Quote Link to comment Share on other sites More sharing options...
IanN Posted January 5, 2015 Share Posted January 5, 2015 Very interesting. Two piece wing, eh? That's an unusual complexity on a model this size - presumably to facilitate the "fit in a box" aspect? Quote Link to comment Share on other sites More sharing options...
Colin Hooper Posted January 5, 2015 Share Posted January 5, 2015 This looks like a holiday special. Small enough to hide in a suitcase and still have room for clothes. I could be interested! Quote Link to comment Share on other sites More sharing options...
trebor Posted January 5, 2015 Share Posted January 5, 2015 Hope you don't mind me watching, I might learn something here ! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 5, 2015 Share Posted January 5, 2015 Tim Beautiful work. What size is the 2s battery? I presume your target is a 160g (6 oz) all up weight? I have a sneaking suspicion that at 22" span you wont need ailerons that big. At these extreme small sizes is an 'exact' aerofoil actually going to make much difference? I my experience anything much below 3" chord is so relatively inefficient (Reynolds number?) that its thickness becomes the dominating factor rather than its section in determining the 'power to fly'. It almost becomes a "thinner the better" scenario hence the remarkable performance that can be achieved by a flat plate wing. I will watch with interest. Quote Link to comment Share on other sites More sharing options...
Martian Posted January 5, 2015 Share Posted January 5, 2015 watching Tim and Happy New Year Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 5, 2015 Share Posted January 5, 2015 I'll build one of those Tim.. Looks great - or do you want to start a free for all and we all do our own variant to the 2 sheets of A3 rule? Subscribing M Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 5, 2015 Author Share Posted January 5, 2015 Thanks all! Vecchio, yes there's two aileron servos - one in each wing, which sort of answers Simon's comment about the inefficiency of such a time wing section - the wings are just there to hide the internal servos! I have several 3S 450 packs in stock, so I'd like to utilise those if possible. If they're too heavy then I'll shell out for a smaller pack. tim Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 7, 2015 Author Share Posted January 7, 2015 Here I've installed the tape-wrapped 3.5 gramme servos, using thin CA. Not an ideal way of doing things, but certainly the lightest! The servfo arms will emerge from their bays when the rx is connected and powered up. With the tops of the wings sanded to remove any high spots, the 1/32" tp skins are added and pinned overnight to let the PVA glue dry. The leading edges are radiussed and sanded smooth. I opted to fit 1/32 sheet facings over the root ribs - just to hide the exposed ends of the spars. Each panel weighs in at 21 grammes. The tail surfaces are cut from light 1/16 sheet, with crossgrain end pieces to prevent warping, The elevator joiner is a length of wooden cocktail stick. Just for fun I've built a little canaliser too..... Quote Link to comment Share on other sites More sharing options...
Vecchio Austriaco Posted January 7, 2015 Share Posted January 7, 2015 looks very nice. Wonder how it will fly. My experience with very small planes is that they are rather difficult to control (for instance Multiplex Fox conversion) - but probably yours has the right size to weight ratio. Looking forward to maiden flight VA Quote Link to comment Share on other sites More sharing options...
Nev Posted January 7, 2015 Share Posted January 7, 2015 This looks fun, how big is the box ? Can't fit in a shoe box surely, will have to make one though. Quote Link to comment Share on other sites More sharing options...
Alan Randall Posted January 7, 2015 Share Posted January 7, 2015 Just needs a nice carrying case to go with it Tim. Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 7, 2015 Author Share Posted January 7, 2015 Vecchio, Netty and I have been flying a pair of Hitec Zippers. These little 24" ARTFs are certainly quite rapid, but quite smooth in flight. The ailerons are positive, but not ridiculously so. The elevator does need to be treated with respect though! You're quite right lads - I'll need to make a custom box. tim Quote Link to comment Share on other sites More sharing options...
IanN Posted January 7, 2015 Share Posted January 7, 2015 Blimey, the modelling pins alone will cost more than the build and fit out - I've never used even remotely that many on wings several times the size. You must have needed a truckload for that 80" Quad On reflection, that could of course quite probably be where I've been going wrong all these years Following this with interest Edited By IanN on 07/01/2015 23:37:01 Edited By IanN on 07/01/2015 23:45:17 Quote Link to comment Share on other sites More sharing options...
cymaz Posted January 8, 2015 Share Posted January 8, 2015 Just a thought, it might have a detachable tail section. That way it could sit in a suitcase or hand luggage. Plane for going on Hols with ?? Quote Link to comment Share on other sites More sharing options...
kc Posted January 8, 2015 Share Posted January 8, 2015 Well I cannot think of a publisher here in South Essex ........we have a large Rc retailer here, a large balsa supplier and a glow fuel maker but nobody publishing plans that I know of! So who could it be? Seems we have to wait...... Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 8, 2015 Author Share Posted January 8, 2015 Posted by cymaz on 08/01/2015 06:57:35: Just a thought, it might have a detachable tail section. That way it could sit in a suitcase or hand luggage. Plane for going on Hols with ?? Cymaz, You're spot on! I'm hoping to have a threaded stud protruding from the base of the fin that will pass vertically through the rear fuselage (trappping the tailplane in the process), and then secure by a nut underneath. It's a system I've used before successfully. Work has started on the fuselage. I've drawn the basic outline.... The fus sides are cut from 1/32 sheet, with internal 1/16 doublers and longerons at the rear. F2 and F3 are simple frames, from firm 3/16 x 1/16 balsa strip. Making them as a single unit, and then cutting them free afterwards helps keep the sides parallel. tim PS. Ian, you can never have too many pins! Quote Link to comment Share on other sites More sharing options...
kc Posted January 9, 2015 Share Posted January 9, 2015 Tim, can you explain that last photo. Is it a neat way of making identical built up formers which are then sawn apart? Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 9, 2015 Author Share Posted January 9, 2015 Posted by kc on 09/01/2015 11:51:34: Tim, can you explain that last photo. Is it a neat way of making identical built up formers which are then sawn apart? Exactly! As long as the longest two sticks are set absolutely parallel to each other, the the fuselage sides should be equidistant apart too. Here're the two sides, together with F1,2 and 3. The formers in close up. F1 is cut from 1/16 ply, and is marked out for the motor mount. The hole below is to allow passage of the cables. Oh.....that's a 5p piece inside F2. The sides are assembled (inverted) to the formers over a drawn centreline, pinned and clamped as necessary. I've added two pieces of the 1/16 bottom sheeting just to stiffen up the assembly. The front former F1 protrudes above the fuselage sides, so I positioned the front ends of the fus sides to overhang the building board. Two bits of scrap ply stop the clamps from marking the balsa beneath. The sternpost is lightly clamped. The little piece of 1/32 ply will, hopefully, line up with the protruding stud from beneath the fin. Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 11, 2015 Author Share Posted January 11, 2015 The high winds have meant lots of workshop time this weekend! The wing panels have incidence pins added (bits of cocktail stick). The actual joiner is a 140mm length of 3mm carbon fibre rod, whilst the piece of bent wire above it is the clip that holds the wings tight to the fuselage, as the two short ends pass through those ply lugs that protrude from the root ribs. The servo leads pass through slots in the fuselage sides. There's a length of plastic tube glued across the fuselage. You can see the wire clip holding the wing panel in situ. Seems to work so far! I've installed a length of 2mm threaded pushrod into the base of the fin. The stud lines up with holes in both the tailplane and its seat on the fuselage. The assembled tail set. Needs a bit of fine tuning, but the principle is sound. The airframe so far! Quote Link to comment Share on other sites More sharing options...
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