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A350-900 70mm EDF 1:40scale scratchbuild

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    #61
    Building the fowler flaps and fibre-glassing

    I have bumped into another road-block as i got some feedback from other hobbyist in rc-groups pointing out that the outboard Fowler Flap won't work according to my design if it was directly attached to the fairings as hinges. The A350 Fowler flap system is unique compared to other types of Flaps such as the A330, A320, B777s as it retracts down and parallel to the fuselage compared to other flap systems which retracts down and perpendicular to the trailing edge. (See picture before for visual reference).

    Also view post #69 to post #80 for the in-depth discussion on the A350 Fowler flap: http://www.rcgroups.com/forums/showt...2263665&page=5

    Had been a long time since I have done something productive to my A350. I have been using the past few days to do primary 2 things:
    1) Figuring out a good solution for the Fowler Flap system - I have decided to use cwrr5 solution to solving the Fairings and Fowler Flap conflict. Right now the flaps and fairings both move independently of each other without any foreseeable issues.
    RC Groups - the most active Radio Control model community: electric and fuel rc airplanes,rc helis,rc boats and rc cars. Features discussion forums, blogs, videos and classifieds.


    2) Been reading up and practicing on how to fiber-glass with different type of mediums as i have never fibre-glassed anything before in my rcplane scratch-building history. One of the useful links i have searched:

    and also back in 2005 in Daddy-hobby forums:


    I have tested 4 different type of mediums to bond the fibre-cloth to the surface and made the following observations:
    1)Marine Poly Urethane - Easy application,Dries hard, bonds cloth to the surface but not as strong as epoxy, Glossiest of them all.
    2)Epoxy - Gets very messy at times, Stiff and solid once cured , bonds cloth to surface extremely well , but heaviest of them all.
    3)White Glue - Easy application, not water-proof ,Dries milky color,the weakest bond of cloth to surface of them all.
    4)Water-Based Poly Urethane - Easy application , Dries hard and slightly glossy, might need to apply 3-4 layers as the viscosity of the urethane is extremely thin which i foresee the longest to work with compared to the rest.

    I eventually chose Epoxy to be used on parts that needed strength (Flaps and other moving surfaces) and Marine Poly Urethane to be used on large area surface skin (General area of wings and fuselage).

    As i'm new to fibre-glassing, i recommend all of you not to follow my techniques in this thread as i'm honestly a newbie in this field and probably already made some mistakes. I just kept a few general rules at the back of my head while working with fibre-glass.
    1) Always a glove to prevent rashes, Always wear a mask for health purposes.
    2) use a squeegee to remove "shiny" blobs before it cures on the surface as those are unwanted dead weight.
    3) Always start from the center of the work piece and work outwards to prevent cloth from moving in one direction.
    4) Keep surface well sanded and clean at all cost before application of the 1st or 2nd layer and so on.

    Below shows the step-by-step instructions on how i work on the fibre-glass and Fowler-flaps.

    And here is the video on the Fowler flap system.
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      #62
      Building the winglet with navigation lights

      The winglet shape is a fairly complex one and requires another technique to hot-wire. To achieve this compound curved shape, It is done by hot-wiring 3 times through the same block of foam by the x, y and z axis. Once it is hot-wired out, it is not finished yet as the winglet still appears "blocky" , the airfoil (clark Y)of the winglet is hand-sanded down carefully to flush with the airfoil at the edge of the wingtip.

      Navigational lights were also added in the process.The wiring was embedded within the foam and covered up with putty to be flushed with the airfoil. A layer of fibre-glass is than applied cover the surface. Notice that the last remaining span of the wing (where the aileron will be) is made out of a solid bluefoam piece instead of ribs is because it gets relatively thin,using the 3mm depron for sheeting won't be practical. The wingroot is 52mm (2") thick while the wingtip is only 7mm (1/4") thick.

      I joined the wing to the fuse to have a rough idea how the A350 is turning out to be . Did a couple of tests while i'm at it, such as deploying max flaps and making sure it doesn't scrape the ground during rotation as the pod fairings is in near proximity to the ground.
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        #63
        Bro i salute you haha amazed at your build and detail to attention

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          #64
          Building the empennage

          Thanks xdrave, so far this is the most complex rc-plane I've ever built, building slowly but surly.

          Both the horizontal and vertical stabs is made out of fiber-glassed blue foam. Servo slots are cut out by a milling tool, The servos are fitted in precisely and flushed with the surface of the stabilizers.

          I have added 2 thin wooden skewers to the horizontal stab, not for adding stiffness but more of a guide to help hold the piece in place while the glue dries. The AOA of the horizontal stab is fixed at 2°, i have no calculations to justify how I derive this value from but through my learning experiences from other airliners I've built,this seems to be the ideal angle to go for.

          As all the parts are coming together and finally taking shape, I've decided to start painting the livery , starting on the vertical stab first which gives me a "warm up" start before the daunting task to cut out spray-paint templates for 112 windows and 8 doors.

          Singapore Airlines will be the choice of livery.
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            #65
            Originally posted by viper1990 View Post
            Thanks xdrave, so far this is the most complex rc-plane I've ever built, building slowly but surly.

            Both the horizontal and vertical stabs is made out of fiber-glassed blue foam. Servo slots are cut out by a milling tool, The servos are fitted in precisely and flushed with the surface of the stabilizers.

            I have added 2 thin wooden skewers to the horizontal stab, not for adding stiffness but more of a guide to help hold the piece in place while the glue dries. The AOA of the horizontal stab is fixed at 2°, i have no calculations to justify how I derive this value from but through my learning experiences from other airliners I've built,this seems to be the ideal angle to go for.

            As all the parts are coming together and finally taking shape, I've decided to start painting the livery , starting on the vertical stab first which gives me a "warm up" start before the daunting task to cut out spray-paint templates for 112 windows and 8 doors.

            Singapore Airlines will be the choice of livery.
            good job

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              #66
              Building the Nacelles

              Thanks Choo

              Going back to the very first post, the EDF and Motor combo i'm using will be the 10bladed ChangeSun EDF with Turnigy L2855-2800 EDF Outrunner
              The motor is rated at 4s but after researching through several articles online,i'm intending to fly this on 3s as the motor + EDF combo delivers sufficient static thrust on 3s to get it airborne and gentle cruising.

              The static thrust of each engine produce is roughly 650grams (23oz) on a 3S with a correctly designed intake lip. The estimated All-Up-Weight (AUW) of my A350 is roughly 2200grams (77.6oz). Thrust to Weight Ratio is calculated to be 0.59:1 . Though the thrust might seem insufficient to get the the plane airborne,there is a difference between static thrust and dynamic thrust. Though i can't explain this mathematically, I am aware that the EDF blades will un-stall itself in flight which results the efficiency of the whole EDF system to increase substantially. Therefore i wouldn't read too much into Static Thrust on my EDF bench tests, its only good to know whether it is suitable for hand-launching, which in my case, i'll definitely go for ROG. After playing around with EDFs for 8 years, it is still a complex topic for me, i have included a few reading materials below for those who want to dive deeper into the topic on EDFs.

              My main objective in building an airplane is always to design an efficient and clean airframe rather than pumping up the watts by increasing motor size or Lipo Cell count. I believe anything can fly, even a brick with enough Watts, but there will be no challenge to rely mostly on power

              For building the nacelles, my objective is to build a it as efficient as possible by:
              1) Minimizing internal drag within the nacelle.
              2) Carefully shaped bell-lip intake.

              Thankfully, the thrust tube of most airliners are extremely short compared to EDF-fighters therefore the losses within the tube is minimal. But i still took measures to smoothen the internal surface as much as i possibly can. An exhaust cone is added to the back to help smoothen the airflow as well as aesthetic purposes.
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                #67
                Exhaust Cone and Engine Pylon Fairings

                Just a minor update on getting the mock-up exhaust cone attached just 3mm or (1/8") shy from the back of the 28mm EDF motor. I doubt the cone will significantly improve the overall efficiency. I haven't got any resources nor the experience but it would be interesting to use CFD to visualize the air flow between a rounded steep taper rear , and a gentle-taper rear (Cone attached) and spot the difference. Other than anything beneficial, it will be just to closely replicate the XWB trent engine on the actual A350.

                Pylon Fairings was also attached. It won't bear any load in-between the EDF to the wing and will be just a "skin" to sandwich the plywood pylon.
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                  #68
                  Building the Spoilers

                  The time has come to cover up the top wing panel with 3mm depron sheet permanently. Before this step, I've triple checked all servo horns, wiring extensions and tightening of screws to preventing a chance for the components to come loose during flight.

                  This is the same way how the under wing panel was done. Uhu-por was first applied on both surfaces of the wing panel and ribs. After 10mins the surfaces become tacky. Once both surfaces are pressed together firmly for a few seconds, the wing panel and ribs will join together with a very strong bond.

                  Spoilers slots were cut out during the fiber-glassing phase. The spoilers were hinged to the wing with another thin layer of fiber-glass. Once the fiber-glass hinged dries and sanded, it would appears almost seamless on the surface of the wing.

                  Here are some pictures and video of the spoilers and flaps in action.
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                    #69
                    To secure the spoilers in the closed position to prevent it from fluttering during fl, I've tried the following 3 methods:

                    1) Springs <-- i found it slightly challenging as I've permanently covered the top wing panel , my fingers can't access the small gaps to glue the spring end. It will get troublesome to cut open the wing panel to work on this.

                    2) Magnet to Magnet <-- Too strong when close shut together, the servo stalled when trying to push open the spoiler.

                    3) Magnet to Screw <-- Magnetic forces to keep the spoiler down can be adjusted by turning the screw so i can fine-tune the strength to hold the spoilers down. The best option so far.
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                      #70
                      Building the Wingroot Fairings

                      The purpose of the wing root fairing is to smoothen the skin gradient between the wing and fuselage. Airflow would be smoother over such surfaces which will reduce form and interference drag.The fuselage fairing piece was cut to shape from a 3mm depron sheet. The fairing is than glued into place and wall putty was added to cover up small gaps.

                      The unique part about this fairing is that it looks different from all the other Airliner I've seen. The A330 has a smaller version of it, but not very noticeable.I've tried googling the purpose of this extended fairings but couldn't find any technical reasons behind it yet. My guess is that it will improve airflow by directing the boundary layer downstream from the trailing edge to the fuselage smoothly.
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                        #71
                        1:400 A350 model

                        I have bought this Singapore Airlines diecast A350 1:400 scale model (Registration No. 9V-SUA) from Phoenix model. This particular model brand is very detailed with their paint job such as the Rolls-Royce and Airbus logo could be read under magnifying glass and the edges delineating the 2 colors are very crisp and sharp.

                        The diecast model will be my guide for the next few weeks to aid me in visualizing details while painting my A350 1:40 model.
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                          #72
                          In the news

                          The actual Singapore Airlines A350 in production as of this week.

                          "Airbus has begun final assembly of the first A350-900 for Singapore Airlines at its facilities in Toulouse, France."
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                            #73
                            Originally posted by viper1990 View Post
                            The actual Singapore Airlines A350 in production as of this week.

                            "Airbus has begun final assembly of the first A350-900 for Singapore Airlines at its facilities in Toulouse, France."
                            http://www.adsadvance.co.uk/singapor...kes-shape.html
                            Great work dude. Thanks for detailed photos of the project. Really wonderful.

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                              #74
                              Originally posted by Rieksts View Post
                              Great work dude. Thanks for detailed photos of the project. Really wonderful.
                              Thanks for the compliment. , i'm happy to share.
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                                #75
                                Spray Painting

                                All the decals will be spray painted on the aircraft except for some extremely small and detailed objects such as the Rolls-Royce logo ,Airbus logo and Singapore national flag will be printed on a gloss paper and glued on.

                                The painting method i'll be using for the decals will be using spray on stencils. The stencils were made by printing out the decal on a piece of paper .After which, I will be using a sharp blade to slowly but surely cut it out to shape (eg. the A350 XWB stencil shown below).

                                I am left with creating the stencil for the 56 windows and 4 doors which is going to be the most tedious stencils I will ever make.

                                So far this is what I've done.
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