Stephen Jones Posted January 24, 2011 Share Posted January 24, 2011 Hi Tim , Love the wing rack nice idea . ... when will that be flying Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 31, 2011 Author Share Posted January 31, 2011 Ooops.....back again! I took some time out to draw the fuselage side elevation, and then take a tracing to build the side frames on. The longerons are from hard balsa as you'd expect, so I found it necessary to horizontally slit the fron of the lower one, in order to get it to curve correctly without tending to spring back. I've tried to emulate the structure of the full-sized Cygnet with its Warren bracing (the diagonal bits). Experience tells that this is the way to build the siffest structure possible. tim Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted January 31, 2011 Share Posted January 31, 2011 Hi Tim looking really good, I have one of those 4260 motors on 5S lipo in my 86" Chipmunk !!! You will have loads of power. I am on a 15 x 10 on the Chipmunk gives around 1400 watts at full throttle. And before anyone says anything a 15.5" prop is scale size for a 1/5 scale chippy Cheers Danny Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted January 31, 2011 Author Share Posted January 31, 2011 Thanks Dan! It's always good to hear some affirmation when you've bought a motor you've never used before! I'm not going to need anything like the power your drawing with a 15x10 prop, so I'm thinking that a 14x8 should be more than ample! How heavy is the Chippie? tim Quote Link to comment Share on other sites More sharing options...
Wolfie Posted February 1, 2011 Share Posted February 1, 2011 I've seen figures of 900w on 5S with a 13x8. 6S with a 15x6 makes it scream slightly: http://www.youtube.com/watch?v=WitlGhkqquM Looking at your lightweight construction Tim, it's really not going to be that heavy is it. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 1, 2011 Share Posted February 1, 2011 Hi Tim, the Chippie is probably double the weight of your wonderful creation, it weighs in at just under 12lbs but that is with 5S 10,000mAh These numbers were gathered in the garden, the 6S A123 is about equivalent to a 4S - 5S LiPo.Seeing these figures has me wondering if the Chippie is actually producing the power I think, probably not the figures don't lie Ah well it will loop from a shallow dive just like a reall chippie so does it matter? I will stick a wattmeter on it next time i fire it up Tim PS I do have a problem with the 4260 range not starting every time the throttle is advanced, its very annoying. These are the only motors I have that do it. Possibly the ESC brand. Though they work okay on other motors. Cheers DannyEdited By Danny Fenton on 01/02/2011 09:22:12 Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 1, 2011 Author Share Posted February 1, 2011 Thanks Wolfie! All that info in very useful. It looks as though I may be over-powering the Ciggie to some extent, although I'm looking for an AUW of around 8lbs or so (don't forget all those acres of Solartex.......). Dan, I'm using a new Turnigy PLush 60A ESC. I've got a couple of these (allied to other Turnigy outrunners) and never experienced any starting problems. We'll have to see what happens when I bolt it all together, won't we? tim Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 1, 2011 Share Posted February 1, 2011 Hi Tim, does the original have ailerons, and will yours? Cheers Danny Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 2, 2011 Author Share Posted February 2, 2011 Dan, The original has huge ailerons on all four wings! No kidding..... This wasn't to cater for 3D aerobatics, but to allow the ailerons to slide over each other when the wings folded back along the fuselage sides. If you look at the wings on my model, the ailerons will extend from the rear spar to the trailing edge. Full span too. I'll cut them free at a later stage. tim Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 2, 2011 Share Posted February 2, 2011 yikes!! you will be measuring the deflection in "thousands of an inch" lol That explains why I couldn't see them, thanks Tim Cheers Danny Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 2, 2011 Author Share Posted February 2, 2011 Dan, I have the micrometer all ready! I'm leaving the ailerons attached until I sort out all the incidences. Anyway, here's a couple of pics of the inverted fuselage sides making the acquaintance of F2 and F3. If they get on, then I'll introduce F1 to the nose area. The extreme rear ends of the fuselage will have bend quite sharply in order to meet up at the stern post, so I've slit them vertically to ease their passage! tim Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 3, 2011 Author Share Posted February 3, 2011 F1 joined its colleagues last night, and the rear fuselage received a few lengths of crossbracing. It all seems suspiciously square so far............Hmmmmmm..... There's quite a pronounced curvature in the rearmost couple of inches of fuselage, so I opted to slit the longerons vertically. ......which makes it a lot easier to bring them together at the sternpost! Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 3, 2011 Share Posted February 3, 2011 Love the idea of splitting the longerons like that Tim, much neater, and I dare say stronger. (Scribbles down in notepad.....) I am sorry to hear that innacurracy has crept onto your building board and you have inadvertently built a stright fus, I am sure you wont let it happen again Cheers Danny Quote Link to comment Share on other sites More sharing options...
Malcolm Fisher Posted February 3, 2011 Share Posted February 3, 2011 I've only just come across this thread, nice work Tim. I too like laminated outlines and have used them on all sorts of models. I never bothered to soak the balsa strips though, just coated them with PVA and used formers for inside and outside made from MDF and clamped together using cling film to stop the outlines from sticking to the formers. As for bending hard longerons, many many years ago I built an Ansaldo for C/L which had ply formers and spruce longerons. These had to be steam bent to shape with curves in two directions. Took me quite a long time steaming them using a kettle on the gas stove... A jig to build the fuselage on was also needed as there wasn't a straight line anywhere. Malcolm Quote Link to comment Share on other sites More sharing options...
Klippy Posted February 3, 2011 Share Posted February 3, 2011 Just tripped over this myself Tim, lovely work, as usual. Quote Link to comment Share on other sites More sharing options...
Ton van Munsteren Posted February 3, 2011 Share Posted February 3, 2011 Tim, What else can I say than that your doing a great job, love the splitting of the longerons. More photos please Ton Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 5, 2011 Author Share Posted February 5, 2011 Posted by Ton van Munsteren on 03/02/2011 21:25:08:More photos please Ton I'll do my best - I promise! Just as an exercise in pointlessness, I thought I'd dump all the bit on the scales and see where where we are at the moment. My apologies for working in imperial units! 4S 4000Mah cellpack 20.4ozMotor/ESC/UBEC 15.9ozServos (6) 11.4ozBalsa airframe 25.1oz TOTAL TO DATE 72.9oz (4lb 9oz)So given my target weight of 8lb AUW, that leaves around 3½lb left for covering, struttery, undercart+wheels, linkages, rx., etc. tim Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 5, 2011 Author Share Posted February 5, 2011 So, here's the start of the metalwork! The cabane struts are cut from 12swg piano wire, and I drew out patterns and and cut balsa templates to keep them as accurate as possible. After all there's nothing worse than a biplane with wonky wings, is there? Then I set about a pice of brass sheet with some tin snips, hammer and vice to produce these little saddle clamps, which will secure the struts to the top of the fuselage. I'm using brass so I can solder the clamps to the struts to aid alignment of the upper wing. More to follow...... tim Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 8, 2011 Author Share Posted February 8, 2011 With all the brass widgets soldered to the struts, I made some mounts out of 1/8 ply, which were then screwed and glued to the tops of F2 and F3. This view shows the underside of the mounts, with the 3mm blindnuts in place. F2 and F3 are gussetted with obechi block. Note the cutouts to allow for the blind nuts! The struts are temporarily screwed in place to check for alignment. What has become apparent is that I mis-measured the rear strut and it's about 2mm too long, which would lead to negative incidence on the wing. No matter - I'll shim up the bottom of the front strut to compensate! The tiny fitments near the bottom of the verticals will allow me to fit static rigging when the model is finally assembled. tim Quote Link to comment Share on other sites More sharing options...
mal brewer Posted February 8, 2011 Share Posted February 8, 2011 Hi Tim, just looking at your latest build,I don't know how you find the time! Regarding the wire cabane struts,which I have been told are correctly called centre section struts,I have found it preferable to use 3mm gas welding rod.This can be obtained from car body garages,and is a mild steel wire with a copper coating.It bends and solders much easier than piano wire,and is amply strong.I have used it on many models,and I am in fact using it on my latest Krier Kraft,which is to 1/4 scale.However,it is not resilient enough to use as undercarriage wire.Try some on your next model,I think you'll find it satisfactory,............................cheers,Mal. Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 9, 2011 Author Share Posted February 9, 2011 Thanks for the tip, Mal! I actually have several bundles of mild steel arc welding rods in my shed (a legacy from my kit-car days......), but never thought to use them for anything other than welding chassis members together! tim Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 11, 2011 Author Share Posted February 11, 2011 Some more progress! It didn't take a genius to see that I made the rear struts a tad too long, when I compared the model to my plan. Look at all that negative incidence! Never mind, it didn't take too long to remake the strut......sigh......... A lot of careful measuring saw the holes bored in the fuselage sides for the aluminium tubes for the lower wing rods. It all fitted first time (which sort of made up for the boo-boo with the rear strut!) Looking promising! tim Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 11, 2011 Share Posted February 11, 2011 Doesn't that look sweet Tim, well done I should bin that centre section jig Cheers Danny Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted February 11, 2011 Author Share Posted February 11, 2011 Dan, My drawing was spot-on! Much better than my measuring prowess anyway...tim Quote Link to comment Share on other sites More sharing options...
Ton van Munsteren Posted February 13, 2011 Share Posted February 13, 2011 Just to let you know Iam still following this build. What can I say more than nice. Ton Quote Link to comment Share on other sites More sharing options...
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