Martyn K Posted February 20, 2012 Share Posted February 20, 2012 Hi all, I have been toying with this for a couple of months now. The raw facts are: Span 800mm, AUW about 800g (hopefully) Section E182 root E184 tip Solidedge plan here (Free draughting software) Delta-a/Delta-a.dft (having problems with this link,please PM me if you would like a copy) PDF Plan http://www.czd.org.uk/aeromodel/Delta-a/Delta-a-plan.pdf Full size ribs here http://www.czd.org.uk/aeromodel/Delta-a/Delta-a-Ribs-3.pdf I am planning to start cutting very shortly, any comments would be very welcome.. Best wishes, Martyn Edited By Martyn K on 20/02/2012 22:17:56 Edited By Martyn K on 20/02/2012 22:19:42 Edited By Martyn K on 20/02/2012 22:21:48 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 24, 2012 Share Posted February 24, 2012 Martyn A nice conventional build and you get browny points from me for 'constructing' a proper tapered spar rather than just using a carbon fibre tube. About the only thing I would suggest is to move the prop as far away from the wing trailing edge as possible both to imporve efficiency and reduce noise. 800g sounds a touch heavy to me but then I do build super light. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 28, 2012 Author Share Posted February 28, 2012 Hi Simon Thanks for the comments. I never relly underatnd why peeps don't cut tapered enything, it is not exactly difficult OK on the weight, I suspect that it may come out lighter when completed, I still haven't actually started it yet as I have been away for a few days and OK on moving the prop back, Should be very easy to do at this time. Martyn Quote Link to comment Share on other sites More sharing options...
Olly P Posted February 28, 2012 Share Posted February 28, 2012 looking good Martyn. how many servos and what controls? I presume: Throttle, Elevons, Rudder? Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 28, 2012 Author Share Posted February 28, 2012 Hi Olly Twin rudders operated from a single 9g micro servo with goldenrod linkages. Two 9g servos driving the elevons plus ESC on throttle. Launching will be via a ramp - it *will* be entertaining which is why there are 2 little underfins half out along the wing. These will act as guides. There is nothing to hang on to although I did consider a discuss launch for at least 5 seconds Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted March 7, 2012 Author Share Posted March 7, 2012 Construction has actually started. About the only thing I am comfortable with is the wing - and as there isn't much else, this seemed like a good place to start. I printed the plan by tiling many A4 sheets using Adobe professional. Not too difficult, especially if you print the alignment marks as well. The PDF link above need scaling up by 141.4%(it is half area size).I'll try and get a proper plan done in the next day or so. The LE needed to be propped up by 6mm at the root and 3mm at the tip. This allowed the rear of the ribs to be placed flat against the board (allowing for 1/32 for the cap strips). The LE and Rear spar were cut from 12mm medium balsa (the hardest that my LMS had so I will be building a slightly stronger spar). The pieces are cut slightly oversize, then pinned together and the double taper was then planed down to approx the final size. Final sizing will be completed during the final sanding. When dry, the panels will be inverted and joined then braced then the main spar fitted. It also needs some gussets fitting at the LE and TE joints. The motor arrived (an eBay special with 60A ESC) from Hong Kong yesterday, it looks a little on the large size... Time will tell. I guess that this will dictate on how long the nose will be to get the CG correct. I am/was planning on a 3S 2200 LiPo for power but have just found out that the motor will take a 4S (1700kV). Comments, advice and/or don't be stoopid type messages are welcome. More to come. Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted March 8, 2012 Author Share Posted March 8, 2012 I forgot to mention. The wing ribs were cut after ironing on the laser printed 'templates' printed using a laser printer. This technique has been well described within these hallowed pages before, but happy to clarify if needed. Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted March 15, 2012 Author Share Posted March 15, 2012 Work on this has been slow to say the least, paid work and household chores are definitely getting in the way at the moment, but I have continued with the wing over the past week. The wing halves were seperated then re-pinned upside down. With the highly tapered wing, this gives a few degrees of dihederal. Don't forget the holes in the ribs. I did and had to cut them (carefully) in situ. (doh) A single 12mm light balsa gusset is located at the LE according to the plan. ... and then the centre rib was added. Upper and lower spars were cut from some rather old 3/32" spruce sheet with a single 3/32" spruce doubler out under the centre 4 bays on each side. I have opted for spruce rather than balsa as originally planned to keep the cross section sizes down. When I use tapered spars, I cut the spar slots by laying the spar over the ribs, cut the slot for the first rib and lay the spar in the first slot, check that the location at the last rib is correct, then cut and locate the spar in the 2nd rib, slowly moving down one rib at a time until all the slot have been cut. When I am happy with the fit, the spar then gets glued in (using PVA). Repeat for all 4 spars and allow the glue to dry. Note the large 8mm gussets at the Trailing edge. This will form the platform for the motor mount. I was originally going to use a block balsa infill to locate the two halves. However, I eventually settled for a 3/32" spruce cross members top and bottom. This will also have 1/16" ply braces to stop the wings falling apart. The 2200 3S LiPo arrived this week. I only bought one, I don'y think it will last long enough to need a second battery.. More to come Martyn Edited By Martyn K on 15/03/2012 23:24:44 Quote Link to comment Share on other sites More sharing options...
Delta Whiskey Posted March 16, 2012 Share Posted March 16, 2012 (Not another delta..) And what's wrong with Delta's ! Quote Link to comment Share on other sites More sharing options...
Martyn K Posted March 16, 2012 Author Share Posted March 16, 2012 Ha ha.. Just too many of em! But you will be Ok - it wil take me ages to get to letter 'W' Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted March 29, 2012 Author Share Posted March 29, 2012 Progress has been very slow. All this nice weather has caused an upsurge in oudoor activities plus family commitments and even worse, no time for flying either. Spars have been fitted and ply wing half joiners inserted. What would have been a much better idea would have been to offset the centre 'bracing' spars so that the upper or lower spar sat behind its oppsite number. The ply brace would have then sat between them in a sort of 'Z' (with a vertical bar) arrangement. This would have spread the load much better. The TE has been added and the laminated fins have been glued up and are ready for fitting. That is the next job, then install the first servo somewhere/somehow to drive the twin rudders. More to come (sooner or later) Martyn Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted March 29, 2012 Share Posted March 29, 2012 Aha, wondered where you had been. It's starting to look like the end [of building ] is not too far away though. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted April 13, 2012 Author Share Posted April 13, 2012 Progress is still slow - the Astro-Hog 25 has been taking priority as I need to get that finished for the RCM&E fly-in - so work on this has been mainly while waiting for glue to dry. The tip fins have been laminated from 2 x1/6" balsa around a 1/32" ply core. I have reduced them very slightly in size from the original plan - they simply looked too big when I originally cut them out. Lower 1/32" balsa sheeting has been added. I have used medium hard quarter grain balsa - it was what I had available and has to take any landing loads - the upper sheeting will be lighter (when I buy it!).. The rudder servo has been fitted - the linkage will use snakes to connect it to the twin rudders. The micro receiver will be located in the adjacent bay. When I get all the radio gear in place, then I can start planning the final fuselage pod layout. However, the next joy will be to build the ailerons, get them hinged, install the aileron servos and then add the webbing and upper sheeting. At the rate that this is progressing, probably about a months work.. I still also need to work out how I will get the motor fitted.. More to come Martyn Quote Link to comment Share on other sites More sharing options...
kevin wild Posted April 30, 2012 Share Posted April 30, 2012 Hi any progress martyn ? kev Quote Link to comment Share on other sites More sharing options...
Martyn K Posted May 1, 2012 Author Share Posted May 1, 2012 Hi Kev Nothing in the last 2 weeks. I have been away for a break and been a bit busy catching up at work, post holiday.... Martyn Quote Link to comment Share on other sites More sharing options...
kevin wild Posted June 11, 2012 Share Posted June 11, 2012 HI any updates ? kev Quote Link to comment Share on other sites More sharing options...
Martyn K Posted June 11, 2012 Author Share Posted June 11, 2012 Hi Kev Funnily enough, I have restarted work on it again this week. I have ordered a smaller motor and ESC - I'll use the others in my Webbit. I am struggling with the rudder linkage , there is not much space in the wingtips to get the bellcranks in.I'll provide a better update towards the end of the week. Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 1, 2012 Author Share Posted July 1, 2012 Today is a bad day. We had water dripping through the ceiling from a leaking hot water tank and I have spent the day trying to drain it to minimise damage until the plumber comes tomorrow. So while waiting for the controlled drips to stop I thought that I would take the opportunity to update this blog. I have to admit though - I would rather be flying.. The project has been put on hold while I finished the AstroHog 25, then practiced for my 'A' certificate and the rest of the time has been spent on maintenance - a posh word for repairs. However, I have spent some quality thinking time - mainly trying to work out how to get the rudder linkages working. In hindsight, and with the benefit of experience, i wish that I had used a micro servo in each tip and direct driven them.. it is what I would do if I was doing this again. I originally intended using a snake to get straight to the rudders, however, the structure and the sharphess of the bend required discounted that idea so I settled on a snake to the tip , a 90 degree bellcrank and then pushrods to each rudder. Unfortunately, geometry got in the way.. To maintain lineraity, the snake pushrod from the servo needs to be at 90deg to the belcrank arm, which is possible, but then the belcrank arm to the pushrod to the rudder isn't, resulting in non linear movement. This was also complicated by the section being only about 8mm thick at the tips. This mistake I made was routing the goldenrods like this: It would have been better and feasible to have routed them like this.. (Obviously with some curves instead of straight edges, but by the time I realised this it was too late. So the bellcrank linkage is as follows: I needed to thin the belcrtanks down by a few mm and they are hinged usinga M3 screw running in 1/32 ply bearers. The arrangement at the root is that both pushrods meet up and a simple pin arrangement will go to the servo to provide the drive. The fact that it is not symmetrical is a not a total crisis, I cant imagine that they will be very effective as they will be out of the propwash. The two pushrods will be joined with a single length of M2 studding.and the pin soldered to this . Elevons have been carefully carved then sanded and added.. and and the elevon servos are added. These are simply inset into the top of the ribs with 1.5 and 3mm lite ply reinforcement each side. Finally (for now), the upper 1/32" sheeting has been added. the LE was carved down to the top of the ribs and then the sheeting laid on top. The whole lot is then sanded down to the correct LE profile, which is where I am up to... I have bought a smaller motor from GiantShark, a higher Kv which will drive a slightly smaller prop. Haven't decided how I am going to fit it though.. its a 2212-06 28A 2200KV SP Brushless Outrunner Motor More to come, hopefully sonner rather than later. One big design change is that I am going to have a go at Thrust Vectoring running in parallel with the twin rudders... Probably another stoopid idea.. Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 2, 2012 Author Share Posted July 2, 2012 Just noticed that one image is missing from above.. so here it is. Sheeted LE upper Regards Martyn Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 5, 2012 Author Share Posted July 5, 2012 Work is progressing at a reasonable rate, but after today, I am away for a few days so not much will happen in the next week. The Elevon linkages have been installed and setup. Make sure that the servos are screwed in properly and that nothing will come loose. The ailerons are now boxed in top and bottom with light 1/16" sheet. This will make the ailerons totally inaccessible without resorting to surgery. Get it right first time. Lower 1/16" central sheeting is added.. and the cap strips. The outer upper bay will be sheeted with 1/32" balsa sheet and then we start work on the engine mounting and lower fuselage. Amazingly, it is still coming together.. More to come Martyn Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted July 5, 2012 Share Posted July 5, 2012 It's looking great Martyn, not long to go now Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 5, 2012 Author Share Posted July 5, 2012 He he Thou hast more confidence than I have Chris. Already taking bets on the life expectancy. If I can get one flight out of it with it still in one piece I will be happy, but to be honest there are simply too many unknowns. But it will be worth it simply as an experiment. Martyn Quote Link to comment Share on other sites More sharing options...
Erfolg Posted July 5, 2012 Share Posted July 5, 2012 Having taken a similar design Pelta and modified into a Depron design with two motors, I have found it surpriingly tolerant of the CG. Lateral roll is twitchy about the horizontal, which has been cured by 50% expotential. I would be surprised if you have any problems Pelta in Depron with a Kline Fogleman airfoil Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 5, 2012 Author Share Posted July 5, 2012 Thanks for the encouraging words Erfolg. That is an interesting Delta, how do you get it airborne? Martyn Quote Link to comment Share on other sites More sharing options...
Erfolg Posted July 6, 2012 Share Posted July 6, 2012 Launching in itself is not difficult. If you have ever seen Zagi types being launched I use one of the methods. An underarm throw, holding the model about the cockpit area. I now have self launched a fair few times now. I have found that a lot of up trim is very beneficial, this ensures it goes up, in a climb out. If flying trim is used, the model streaks away at the same height as to your hand at launch, my model gently turns left at this stage, in this turn it starts to loose height, remember we are only at 1m. You then are desperate to get to the sticks before it touches down, at speed. Up trim, full power and life is rosy. My delta likes big manoeuvres, tight turns, burn of speed, dramatically. The turn into land needs care, if speed is reduced. It can just drop out of the sky. I have done it. Just flops down. I have limited delta wing experience, although I have now flown a number of flying wings. In many ways they seem similar. Flying wings do not seem to stall in the conventional manner, they just seem to nod at the stall loosing height. My delta, does not nod, it drops like a pancake. So slowing down to land needs care. Do all deltas do this? I do not know. Quote Link to comment Share on other sites More sharing options...
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