Stuart Eggerton Posted September 23, 2011 Share Posted September 23, 2011 Hi all, I have decided to have a go at building a Zogling gliding, I think it's other name is the SG38? I think a good span would be 10ft and I have a set of plans that I will scale up . Now looking at the plans the wing section is flat bottomed, but on pictures and video's I have seen of the Zogling (SG38) the wing section looks under-cambered. I wonder if anyone has information as to the actual wing section that the original glider used, as it would be nice to remain on track with regard to scale detail Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 23, 2011 Share Posted September 23, 2011 The main function of primary trainers was to train pilots in the elementary control of gliders and not really designed for much more than short hops and ground slides or delayed plummets down to the bottom of a hill to qualify for the basic certificates. Some limited soaring was possible but the wing section was "built for comfort not speed" so the results of a scale section might be rather limiting even with a fairly large scale model. There's quite a bit of apparently authentic full size info on this page including a fairly detailed 3 view drawing, if you haven't seen it....Edited By Martin Harris on 23/09/2011 14:10:09 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted September 23, 2011 Author Share Posted September 23, 2011 Hi Martin, thanks for your reply, yeah I know it's no floater! I think the glide ratio is 1:10 which is a bit poor when you compare to an ASK 13, which is 28:1 and the high performance glass ships of up to 60:1, but I think it would be a good deal of fun and look the part. I am thinking of using a bungee to launch it to gliding height, obviously an electric motor would spoil the lines. Maybe though an electric motor could be added later if the glide is really dreadful to get some duration flights, who knows. Maybe that's why the airfoil on the plan is flat bottomed for simplicity?. Thanks for the link, I have discovered that link before but thanks anyway. Quote Link to comment Share on other sites More sharing options...
Conwy Soarer Posted September 23, 2011 Share Posted September 23, 2011 Free plan here: FUSELAGE & WING I think the full size had something like a Gottingen 426, the plans above are 1/5 scale, found them a while ago with a view to building one. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted September 27, 2011 Author Share Posted September 27, 2011 Thanks for posting links to the plan, guess what, I am using the same plans! how spooky. I noticed though the link to the 'wing' plan does not work, but thanks for posting . My next step (which I began yesterday) is to up scale from the 1/5 scale plansto my 10ft version. I am sure that there are photocopiers out there to do the job but I have undertaken the old task of using a pencil, calculater, ruler and set square to scale her up! So far with a wingspan of 10ft the model looks huge as the chord is 487mm! and the Gottingen section is not thin! Go to do a final check to see if the fuz will fit in the car, the wings should not be a prob as 5ft each. If it is a prob (looks tight) then I could make the fuz join in the centre. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted September 30, 2011 Author Share Posted September 30, 2011 Hi everyone, if you use the plans for the Zogling please note that the wing and the fuz are on two different plans and if you print them out they are different scales. You can also find the plans here I had to apply different scaling to the wing than to the fuz to get it correct for a 10ft span. My model will turn out to be approx 30% size of original. Here is an example of a 1/3 scale Zogling build on the rc groups website and this will be a valuable resource in building mine. Edited By David Ashby - RCME Administrator on 30/09/2011 14:03:37 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted October 8, 2011 Author Share Posted October 8, 2011 The plans for the Zogling have been increased in scale so the final model wing span 10 feet, which I think is a good span. It's amazing how a model with a big wing chord can look so big!.I am waiting for my timber to come from the Basla Cabin, and then let the building commenceth! Quote Link to comment Share on other sites More sharing options...
Lazygit Posted October 8, 2011 Share Posted October 8, 2011 Here is some background for primaries, Slingsby's T38 used the Kirby kite section (Göttingen 426). Note the rip off cost in 1939 "Slingsby Sailplanes Ltd were offering new gliders from £99. A Kirby Kite 1 cost £159". Considerably less than a kit might be today. Wiki gives the SG38 wing section as Göttingen 533 and the elevator and rudder as naca0012f60. There's a mention elsewhere of a Göttingen 535 for the wing. Bearing in mind models rarely scale well, it may not matter too much. Edited By Lazygit on 08/10/2011 17:03:11 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted October 10, 2011 Author Share Posted October 10, 2011 Hi Lazygit, many thanks for the info, I think I will go for the Gottingen 533 for the main wing and not the 426 as the pic above shows, so will print off the section at 477 mm chord and post it on the forum to show, like I have done above Wood still not arrived so that's OK! Quote Link to comment Share on other sites More sharing options...
Taco Posted October 12, 2011 Share Posted October 12, 2011 Another try: could not post lately.Have a look at: rc-gliderparts.com. There is a link to: schulgleiter.deLots of information, pictures etc. Taco. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted October 13, 2011 Author Share Posted October 13, 2011 Thanks Taco, very useful site, will download information when I get some spare time lol!! Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted October 24, 2011 Author Share Posted October 24, 2011 A rib at last! thanks to the work's photocopier, shhh!! Next is to cut the rest of the ribs ( all 32 of them) the wing root ribs will take 7mm brass tube for the wing joiners and will pass through the first 3 ribs in each wing. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted October 29, 2011 Author Share Posted October 29, 2011 Copied all the rib templates to paper and cut them out Stuck each rib template to a 1/8 thickness sheet balsa All the wing ribs (including aileron ribs) cut out. It has surprised me how long this process took, but she's coming on! Quote Link to comment Share on other sites More sharing options...
Taco Posted October 31, 2011 Share Posted October 31, 2011 Normally with these ribs, i bolt all them together with a template on each side. And then i sand them down to the template. Taco. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 1, 2011 Author Share Posted November 1, 2011 Hi Taco, yes that's the tried and trust sandwich method if I'm not mistaken. I had to cut out the lightening holes anyway so thought I would do it this way and it seems to work OK. I have sheeted the inner most ribs (x3) with 1/16 ply, see pic below The two bottom spars has been spliced and cut to length. The next stage will be to set the airfoil up on blocks as it's an under cambered section this makes it tricky to build. I have cut the blocks out of balsa and they will support the front and back spar off the building board by just the right amount. The trailing edge is just 1/16th sheeting. Got to figure out where to run my wiring for the aileron servos. I think it would be easier than using wires and bell cranks to just put a couple of servo's in the wings. I thought I might hide the cables in in front of the main spars and behind the leading edge, this would require either circular holes of a square hole to be cut in the ribs. The model will be covered in nylon and I won't want to see aileron servo cables through the covering!!! Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 5, 2011 Author Share Posted November 5, 2011 Root rib example with holes for 7mm brass tube wing joiners drilled, note the notch in front of the bottom front spar notch to allow aileron servo cable to pass through.(below) Note small rectangular hole to take servo lead for aileron (below) Rear spar piece that joins onto the back of wing where aileron joins and the corresponding spar (aileron LE) pieces, two per wing. These may need sheeting and some cross members to stiften them up. The wing bit will need shaping /bevelling to allow the aileron to move up and down. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 7, 2011 Author Share Posted November 7, 2011 Below are the ply braces for the ailerons. made from 1/32 ply sheet. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 7, 2011 Author Share Posted November 7, 2011 Does anyone know if the Zogling primary glider had any washout incorporated into the wings? Do you think I should incorporate some in anyway? and how much washout is usually acceptable for a glider like this? I don't know what the tip stalling characteristics of this glider were like. Quote Link to comment Share on other sites More sharing options...
Taco Posted November 7, 2011 Share Posted November 7, 2011 As far as i know it has not any washout. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 7, 2011 Author Share Posted November 7, 2011 Thanks Taco, they probably hadn't invented washout when the Zogling was made lol! Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted November 7, 2011 Share Posted November 7, 2011 Hi Stuart A small amount of washout ,gives that extra safety margin ,but not realy necessary on a lightly loaded low aspect wing Tom. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 8, 2011 Author Share Posted November 8, 2011 I have started to make a wing at long last!. In the pic below, I have pinned down the front and back lower spars to the plan and added the block balsa leading edge, the ribs, trailing edge sheeting, from 1/16th balsa sheet, and also the shear webbing. The ailerons have yet to be made. The next stage is to add the upper rib capping from 1/16th balsa sheet and get the servo's in and the servo extension wires before sheeting from the leading edge to the main spar. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 8, 2011 Author Share Posted November 8, 2011 Hi Tom, just seen your message! OK thanks for the info regarding washout Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 16, 2011 Author Share Posted November 16, 2011 Progress so far on the Zogling. I have been focusing on building the wings. You can see both wings in the photo below. The wing tips have yet to be added. I need to add the rib capping and bottom sheeting to the right hand wing (left is done) Also need to add 1/16th balsa rib capping (9mm wide) to the top of both wings as well as top sheeting, but need to thread aileron servo wires through first. I have ordered two servos for the ailerons from Giant Cod, and the the system will use pull pull cables. I have not added in the shear webbing between the inboard 2 ribs as need to fit the brass tubes and get them aligned first. Also I will add 0.5mm by 10mm carbon to the upper spar well out to the first 1/3 of the span, in fact 500mm out. This should help the spar take loads in compression as will use a bungee as well as aero-tow for launching. The underside of the wing showing 1/16th balsa rib capping (9mm wide). You can also see the shear webbing. Below, you can see the two attachment points for the wire bracing (for the bottom of the wing). The same applies for the upper part of the wing in the same place. Below is the aileron in-situ. I decided to make the trailing edge a bit wider than scale as used 1/16th sheeting top and bottom. I will put another strip of 1/16th sheeting in the gap between the two 1/16th balsa trailing edges to stiffen things up. Below is one of the ailerons. The leading edge needs to be shaped to allow aileron to move up and down. Edited By Stuart Eggerton on 16/11/2011 11:35:53 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted November 16, 2011 Author Share Posted November 16, 2011 Below is a picture of the progress made so far on the boom. This is made from 12.5mm square spruce strip. I had to cut down the wood to 9mm thickness as this is correct for scale. You can see that the original 12.5mm thickness still exists where the members join but will be hidden behind the ply braces when added! I have pre-cut slits for the rudder hinges (easier to do this before assembly). The 1/8th balsa pieces actually seal off the airflow from getting onto where the ply braces are to cut down drag. Below is close up of typical joint. Next stage is to give it a good sanding to get joints level and then add 1/64th ply braces both sides. Edited By Stuart Eggerton on 16/11/2011 11:43:31Edited By Stuart Eggerton on 16/11/2011 11:44:32 Quote Link to comment Share on other sites More sharing options...
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