Former Member Posted May 30, 2018 Share Posted May 30, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
michael harper 2 Posted June 4, 2018 Share Posted June 4, 2018 Looking very good Chris. I started drawing on a drawing board years ago and saw how it was changing to computers, so I did a course on AutoCad. The company I was working for installed Microstation which is so easy to use. Never looked back. Just send me a message if and when you need a hand. Cheers Mike Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted June 5, 2018 Author Share Posted June 5, 2018 Hi Mike. How would you work? RCM&E CAD my pencil plans, but I have to do the drawing and annotations. I guess I would have to do the same for you? Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted July 11, 2018 Author Share Posted July 11, 2018 It's amazing that six weeks has passed since the last build update. There's not much to show for the time either as I'm at the stage where small details take a long time to do. The top and bottom of the fuselage are now sheeted and the fairleads for the closed loop tail surface control cables installed. There is a lot of work to do to finish the wings, but I have installed the aileron servos using a favourite, fix them on their sides to a thin ply plate, method. The wings now need final sheeting of their centre sections, installation of all the wiring with plug and sockets at the joints, struts sockets, and getting a precision fit where they join the fuselage. The engine nacelles will need the same care to fit them to their position on the lower wings. Beneath them, I have to make up the dummy oleos for the undercarriage. They will be close to scale in appearance, and will have some springing as I know from experience that inflexible undercarriages don't work well. Looking ahead. With the demise of Solarfilm, the model will be covered with Hobbyking film - a good product that shrinks well, albeit it doesn't stretch as well as Solarfilm. I have been trying to find a paint to match the red film as Hobbyking don't make exactly matching paints like Solarlac. A Humbrol red in either enamel or acrylic looks like it will do. It will be needed for the wing struts, and possibly the nacelles if the compound curves prove too difficult to cover with film. An aside reflecting modern times. Yesterday afternoon at 1430 I ordered some servo extension leads on eBay. They were delivered at 1100 this morning! I have been chatting with RCM&E editor Graham Ashby and have pretty well agreed that I will offer the Dragon as a plan for the magazine in due course. In parallel with this blog, I have been taking build pics and writing construction notes as the build progresses. I hope it flies! Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 11, 2018 Share Posted July 11, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted July 13, 2018 Author Share Posted July 13, 2018 I've used lots of the Hobbyking cheap small servos Percy, mainly the HXT 900 and 500. I don't do deep cycling just run them a little on the servo tester to ensure they work properly. After all, in the air, they aren't motoring most of the time. Buried in the airframes I've never bothered to check for warmth. I have only had one fail and it ran away to full deflection on an aileron on a first flight - see my Vickers 151 blog elsewhere here. Hobbyking admitted that they had had failures due to poor quality gears, my failure, and refunded the cost. This was a whole $2.50! My scottish ancestry means that I tend to buy at the cheaper end of the equipment market. Almost everything we buy these days is made in China, and by and large we get great value for money. In the early electric days I bought a small brushless motor and esc package at a special Show price of £90.00! I'd just sold a design which paid for it. The same outfit would be a quarter of that today. Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted September 27, 2018 Author Share Posted September 27, 2018 It's been a long glorious summer, but it's meant that the Dragon build has slowed down. Holidays with grandchildren, and repairs to parched grass have taken their toll on the work rate.l. However, I've now got back to the build and I'm on to the fussy final fitting stage which always takes much longer than you expect. The metal tube components of the undercarriage oleos are done but now need their streamlined fairings. The servo wire connections for the ailerons across the wing separation joint are also 90% complete. I've used the system I used on my DH60 Moth. The centre section female connector is glued into a small slot in the joint rib. The outboard, removable, bits of the wing have a small box built into their inboard ends with a larger slot in the rib within which three inches of servo cable with the male connector can be stowed. When the wings are joined, the carbon rods are slid into their tubes and the cable extended to plug into the centre section socket. When plugged in, the wing can be closed up to the joint, and the excess cable tucked into its little box. I haven't sorted how I will lock the wings in position yet, but a wire U shape like a large staple that will insert vertically across the joint is a favourite idea. Two small other jobs done are fitting in the 16 pieces of 1/2" balsa with a small slot in them which will take the 8 wing struts. These will be made from streamlined metal tube with 1/16" ply ends. Once the wings are finished and covered, the slots will be opened up and the wings assembled on the fuselage. The struts will then be plugged in and secured with a dab of cyano, or maybe PVA. Each strut will have a small hole drilled at its end through which I will thread some bright silver cotton simulating the stainless steel bracing wire of the full size. The model is too small for proper bracing wire end fittings, and in any case the wings will not need bracing for rigidity. Finally, I've started finishing the nacelles with sanding sealer and dope prior to painting them. I decided that Hobbyking film won't stretch around the compound curve shapes. A Halfords aerosol of Fiat orange red looks like the right shade to match the film. However the full size aircraft has different shades of red on various bits so it will be sort of scale if it doesn't quite match. ! Quote Link to comment Share on other sites More sharing options...
michael harper 2 Posted November 29, 2018 Share Posted November 29, 2018 Any updates on build ? Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted November 29, 2018 Author Share Posted November 29, 2018 Slowish progress Michael, but some has been made, and all of the woodwork is finished. This latest pic shows the final build with the ailerons installed and, not visible the lower rears of the nacelles. The undercarriage oleos are on board with their streamlined fairings, and all the wiring to aileron servos and motors is in place. The oleos have springs inside their aluminium tube structure as I discovered when building my Scottish Aviation Pioneer that rigid dummy oleos deform if landings are heavy. All that remains now are the 4 inner and 8 outer wing struts and covering. I'll use red and white Hobbyking film, and have found that Humbrol 19 red enamel is a good match for the film so I will probably hand paint the nacelles rather than mask up and spray with an aerosol. The decals have been made by my local friendly sign maker. The struts and dummy rigging will be installed after covering when the centre sections of the wings will be fixed semi permanently in place, and the outer wings plugged in in pairs for flight. I've done a "show and tell" session at my Club when the model was well received. It's been fun to do, but taken rather longer than I expected. I suspect I'm slowing down as anno domini advances! Quote Link to comment Share on other sites More sharing options...
michael harper 2 Posted February 2, 2019 Share Posted February 2, 2019 Looking good. Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted February 9, 2019 Author Share Posted February 9, 2019 Well, we finally got there. After just over a year in production, the Dragon is 99% done. I just have to calculate the CG position, then finalise the battery location, and do some weight and power measurements. The final finishing was uneventful but took a long time. It serves me right for going for the vanity "Chrisair" colour scheme. However, now that it's done I'm pleased I went to the effort as it is an eye catching finish. The Hobbyking film went on well as always, and the minor wrinkles were easily ironed away. The assembly of the wings into two permanent box structures proved straightforward . The wood tipped streamlined metal struts were plugged into their PVA glue filled slots in the wings and the whole, very wobbly, structure plugged into position on the wing centre sections to set. One the glue had set, the wings could be slid off the centre section in pairs as planned, and their replacement takes only moments. They are retained by what looks like a large staple that fits across the wing joints at the main spar position. The ailerons have a clevis and carbon rod connector bottom to top from the servos in the lower wings, and look to work well. At the top and bottom of each strut there's a small hole which I threaded up with cotton rigging. I'm not too happy with the result. I had found some bright silver cotton to simulate the stainless steel wire of the full size. However, it proved to have no strength at all, and was replaced with a stronger black thread. It sort of looks the part, but it serves no real purpose, will add drag, and you won't be able to see it in the air. I may remove it again. My Dragon is not super scale as I have made some minor alterations here and there to ease the build, and also to slightly enlarge the main planes chord as I felt that the scale chord looked very narrow. I don't think any of the mods are obvious, and I'm very happy that my Dragon represents the full size aircraft pretty well. I just hope she flies as well as she looks. Test flight report pending subject to better weather and the availability of my Club Chairman test pilot. Quote Link to comment Share on other sites More sharing options...
GrahamWh Posted February 9, 2019 Share Posted February 9, 2019 Lovely build Chris and a clever way of dealing with the wings. Is there any chance you could show a close up of the staple method you describes that holds the wing sections together? Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted February 9, 2019 Author Share Posted February 9, 2019 Hi Graham. No sooner said than done. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted February 9, 2019 Share Posted February 9, 2019 hello Chris,very nice model- well done... ken anderson...ne..1..rapide dept. Quote Link to comment Share on other sites More sharing options...
GrahamWh Posted February 9, 2019 Share Posted February 9, 2019 Thank you very much Chris - I have been puzzling about some sort of connection to use for some time. Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 10, 2019 Share Posted February 10, 2019 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
michael harper 2 Posted February 17, 2019 Share Posted February 17, 2019 Very impressive. Hope it flies well. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted February 17, 2019 Share Posted February 17, 2019 Looks superb Chris. An excellent result. I'm really looking forward to a flight report. Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted February 17, 2019 Author Share Posted February 17, 2019 Thanks for the compliments guys. I've done the weighing and power checks now. The latter proved a bit of a puzzle as I'm only pulling 210W on 7x6" props from both motors from 2x2200 3S lipos in parallel; my standard for larger models. The Hobbyking spec for the Turnigy 2863/8 1100Kv motors says they pull 336W each at 18A and 15v, which I should have spotted is rubbish, as others have recorded on forums various. The model weighs 4lb 12oz ready to fly which around 40W/lb, rather less than some of the tables suggest for good performance. However, as fellow clubmates and I have found, brushless motor watts go further than old brushed motors watts, on which the tables are based. The static thrust is 2lb 2oz which ought to be enough. It's a vintage biplane not a pattern ship! I've done the CG calculations which are not wholly straigtforward for a swept winged biplane. I hope I've got it right. I just need a fine day and a friendly test pilot now. I'm a safe flyer but I'm not up to first flight out of trim surprises. Quote Link to comment Share on other sites More sharing options...
Trevor Posted February 17, 2019 Share Posted February 17, 2019 7x6 props are a bit on the small side for 1100kv motors on 3s batteries. I’d be tempted to fit 8x6 or even 9x4 for the first flights. Trevor Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted February 17, 2019 Author Share Posted February 17, 2019 Alas, scale being what it is, 7" props are as big as I can go! No room for bigger. Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted February 17, 2019 Author Share Posted February 17, 2019 Good thinking Trevor. I bought unsuitable motors having been fooled by the promise of 336W. I've just been out to measure the gap between the engines and fuselage. 8" props might just fit, they certainly will if I trim the tips a tiny bit. I'll buy some 8x6" props and give it a go. Quote Link to comment Share on other sites More sharing options...
Trevor Posted February 18, 2019 Share Posted February 18, 2019 In case it helps, the stats for my Rapide are here: **LINK** It has plenty of power at 55w/lb so I'm sure you could fly at around 30 - 40w/lb but it wouldn't leave much in reserve while coping with any trim issues on a maiden flight. Temporarily fitting 3-blade props or going to 4s batteries would be other ways of getting a power boost if prop diameter is a constraint. Good luck! Trevor Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted February 18, 2019 Author Share Posted February 18, 2019 Hi Trevor, My Dragon is nice but your Rapide is very nice! Lots of interesting stuff on your link Did your weight of 5lb include the 3 batteries? If so your build was much lighter than mine. Chris. Quote Link to comment Share on other sites More sharing options...
Trevor Posted February 18, 2019 Share Posted February 18, 2019 The weight includes one 3s x 3300mah LiPo. The Rapide was kept light to reduce the tip stalling risk. However, it is arguably too light! In anything other than flat calm it looks very untidy being bumped around by slight turbulence. I added an Eagle Tree Guardian 3-axis stabiliser a couple of years ago and that has made flying in a breeze a lot more pleasant. At the risk of going off topic, if anyone is fancying building one of these DH biplanes from an Ivan Pettigrew plan, I should mention that the Rapide is one of Ivan's earlier plans and he's refined his design and drawing methods a lot since then, so the Dragonfly and Express are much more straightforward to build. Quote Link to comment Share on other sites More sharing options...
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