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Carl Goldberg Sophisticated Lady

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    Carl Goldberg Sophisticated Lady

    This design is a facelift version of the venerable Carl Goldberg Gentle Lady. I bought a laser cut kit many years ago, but gave it away to a friend, thinking that I won't be building it. I came across the kit a few years ago during a year end sale of a local hobby shop, and bought it again. The fuselage lines sure have some charm which is too hard to ignore.

    What was holding me up to start building it, was my wonderful ideas of hopping up the design further, which never materialized. It is only until recently, I decided to temporarily hold back the ideas start building it, and see if I bother to modify the design along the way.

    I figured out that with such simple design, I can always build a pair of new wings later with ailerons if I want to and do not want to waste too much materials in the kit. As such, the wings are built almost fully stock. However, there is something I would definitely want to modify, which is the vertical stabilizer. I had earlier designed, built and flown a 1.5metre version of the Sophisticated lady, and although it flew great, the original vertical stabilzer design is weak, and it broke once during a bad landing. It is filmsy enough to cause the entire tail assembly to rock when you shake the fuselage. Even with a carbon strip reinforcement, it can still twist easily from side to side.

    So, I redesign a fully built-up integral vertical stabilizer, which blends with the fuselage cross sections. It is now much stiffer and stronger and take some punishments on slope better than before. What's more? The thicker fin provides enough space and material to accomodate a removal horizontal stab mounting system. But because of all these modifications, the rudder cross sections will need to be changed to blend with the fin. Subsequently, the rudder is also redesigned and fabricated from raw materials.

    I had previously face some difficulties on covering blended vertical and dorsal fin with film, I opted for glassing the fuselage and paint. I used Sig regular weight cloth with Pacer's laminating resin, before applying coats of primer with rubbing down in between, before the white 2K paint. I intend to coat it with 2 part lacquer later.

    Although the fuselage took some additional weight, I saved some on the wings using Oracover light transperant film, and mini servos. I still have some final works on this project, but I weighed all the parts together and it now tipped at 28 oz. I would expect the weight to increase to 29-30 oz once completed. Although it is par or a little heavier than the ARF version's stipulated weight, the wings are large enough to take the extra weight, and my heavy duty Hi-start will have no problem hauling it up to the heavens.


    #2
    Yes... and this is mine.

    I didn't have much problems with covering the vertical stabilizer because I did it separately as opposed to the method suggested in the instructions. Didn't have problems with covering using such a method.

    No doubt, the glider is pretty weak in the tail. I have searched around and made a thread in RCG asking for a few suggestions on strengthening the tail and there have been a few suggestions. I went ahead with bracing the tail with string (in my case, dental floss), which is claimed by the designer of this idea to allow him to have "5 years" of unfettered flights instead of 5 minutes. We will see how this lives up.

    Weight so far with two tua liap servos and a Rx is 1.4lbs, 22oz. Lots of ballast needed for this truly tail heavy beauty! Covered with Hobiking covering.

    Last edited by csisfun; 21-12-2010, 11:45 AM.

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      #3
      Originally posted by csisfun View Post
      Yes... and this is mine.

      Weight so far with two tua liap servos and a Rx is 1.4kg, 22oz. Lots of ballast needed for this truly tail heavy beauty! Covered with Hobiking covering.

      D'oh, why is this glider so heavy? Is this an ARF? No right?
      "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

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        #4
        Yuen,

        1.4kg is 3.08 lbs, also 49 oz. Not 22oz.

        For slope soaring is not a problem. However, it sounds a little heavy for flat land thermal soaring.

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          #5
          Originally posted by joe yap View Post
          Yuen,

          1.4kg is 3.08 lbs, also 49 oz. Not 22oz.

          For slope soaring is not a problem. However, it sounds a little heavy for flat land thermal soaring.
          Sorry, 1.4lbs!

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            #6
            1.4lb without batteries. 4 AA size battery pack should weigh another 3oz, bring the total functional weight to 25oz. Still very light.

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              #7
              Really nice guys. Love the pilots in the cockpits.
              Can't wait to see them on the slope.
              Gotta get around to building the Bird of Time kit that's sitting next to my bench. Plan on adding spoilers to it.

              _David-

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                #8
                This morning, I sprayed a few coats of automotive 2-part clear coat. I really like the result. Although can be better, the fuselage is already quite shiny. Furthermore, this clear coat is supposed to be impervious to most solvents, which means that I can easily remove any stains with paint thinner without harming the paintjob.

                I also added the decals on the vertical fin. Just by looking at the fuselage, anyone can imagine a scale glider zooming pass. In fact, just a little more rounding of the fuselage corners and changing to a pair of high aspect ratio wings, it can easily pass on as a 'scale glider'.

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                  #9
                  I got everything rigged up and balance by this noon. In the evening, I had a little window of opportunity to do some test glide. I quickly took my self made Up-start and head to the field.

                  I did an initial glide test, and it has completely no surprises. A usual long and flat glide can easily be achieved with just a light toss. However, at this low altittude, I can't really test out the rudder response. So, I went back to my car and took out the upstart.

                  I started to unwind the bungee out from the spool and to my dismay, I realised that there is no towline to be found beneath! All I have is just the 12metres of bungee cord. I had previously discarded the entangled towline but forgotten to reload the spool before putting the bungee cord over it.

                  I was about to pack up, but suddenly got the idea of just shooting up the Lady with whatever stuff I have left. I stretched out the bungee as far as it can go and hook up the ring to the tow hook under the lady's fuselage. I had yet to try this kind of launching, and after a brief moment of self calming, I pushed the lady forward and let it go. The bungee swiftly pull the lady up to about 7-8 metres in the air, but without the towline, it began to pull the lady level and downwards after passing the apogee. Instead of pulling up elevator to disengage, I push the nose down a little and let the bungee pull it towards the ground briefly before yanking 'up' elevator to disengage.

                  The extra energy imparted allows the model to climb further up beyond the bungee's peak of the trajectory. This is commonly known as "zoom" launch, but I was merely doing a mini version of it. Having done that, the model was brought up to only about 15 metres in the air, with this short bungee. Without significant thermals, I got about sub 2 mins air time on each launch, but by the end of the 3 launched I did, I have already trimmed the model out, and fine tune programming and check out the model for any bad habits.

                  At 29oz, I wouldn't say that it is a best floater I have flown before. But the glide ratio and response is much more comfortable with this model, in our usual windy climate. Unless we are flying in absolutely still air, we do not need to go super light. If I have the chance tomorrow, I'll go for full Hi-start launches to seek for real thermal business.

                  Comment


                    #10
                    Nice Joe. Way to improvise.

                    -David-

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                      #11
                      Painters kit

                      Hey Joe! Merry Xmas That's a gorgeous finish on that fuse. I've got an e-Wasp fuse that's been rubbed down and ready for a finish. Care to share a couple of pointers - like what your airbrush kit is and where you get your 2-pack paint?
                      sigpic
                      ... Why does everything I think I need always come with batteries?
                      John Mayer

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                        #12
                        Hi Terrance,

                        Merry Christmas to you too. I was only using a cheap spray gun and a mini air compressor for plastic modelling. You don't need to buy expensive airbrush system for this kind of paint job, unless you fancy putting some soft camouflage patterns.

                        I buy my 2K paint and lacquer systems from Tonita, 50 Paya Ubi Crescent. They don't really come cheap, but with 1 litre of quantity, you can paint your entire car. The paint is 1 part only, and will be dissolved by solvents even after curing. But the 2 part lacquer will provide the shine and protection against solvents and many other chemicals.

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                          #13
                          By the way, I flew it again 2 days ago with my heavy duty Hi-start. The longest flight I've got is 12 minutes soaring on multiple low level weak thermals. The winds are strong and tends to break up thermals sooner than usual before they can joined to form much larger and more powerful thermals. As such, the highest altitude I've flown that day wasn't anything impressive at all.

                          During one of the launch, the wind was picking up and I have left the elevator trim a little to much 'down', from the previous flight. The climb was slightly shallower and the Lady picked up a little to much speed that cause the wings to flutter. I quickly added a few clicks of 'up' trim to slow it down and steepen the climb, to prevent the wings from breaking up. The wings stopped fluttering immediately and I had an uneventful flight. After landing, I saw some small creases over the wing LE sheeting. Next time, I think I'll use the standard Hi-start instead.

                          Comment


                            #14
                            I've on two occasions took this plane out and I found it to be the most awesome plane to fly. Mine turned out to be around 31 oz (new $15 digital weighing scale!), and still is a strong slope soarer, especially when the wind is weak. This thing needs less lift than dedicated sailplanes, but when the wind becomes strong, it kinda isn't that good. Just my opinion.

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