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A350-900 70mm EDF 1:40scale scratchbuild

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    A350-900 70mm EDF 1:40scale scratchbuild

    Hi to all my fellow modelling enthusiast!

    A little background
    I felt a huge urge to kick start my new scratch-building project after watching couple of short clips on the actual Airbus 350 from it's initial design stages to it's maiden flight. The A350 will serve as a competitor to Boeing's 787 to compete in this long range,low fuel consumption and composite material build era.

    I would like to share this build with all of you,in an attempt to build a RC A350-900 from scratch till it's maiden flight just like how the Airbus team did it but the only draw-back will be, this is going to be a one man team.

    You may help me to provide any positive or negative feedbacks in anyway possible that will aid and improve areas such as building techniques, materials,electrical components,painting methods and whatnot. I'll also be happy to answer any questions asked along the way.

    History
    This will be my 4th Airliner build till date,
    1)B777-200 (Year2008)
    2)B787-900 (Year2009)
    3)B727-200 (Year2012)
    4)A350-900 (Year2014) <-- New build

    Building Specifications
    Scale - 1:40
    Estimated Weight- 2000Grams (70.55oz)
    Wing Area - 2.47 ft²
    WingLoading - 28.47oz/ft²
    Cubic WingLoading - 18.08oz/ft³
    Thrust - 1300 grams static (45.85oz)
    Main wing Airfoil - Clark Y
    Vertical and Horizontal Stab Airfoil - NACA0008

    Main Components
    ESC - 40Amp Turnigy x2
    EDF - Changesun 10 blade 70mm x2
    Motor - Turnigy L2855-2800 EDF Outrunner x2
    Retracts - Turnigy Alloy Servoless Airliner Retracts w/Sprung Oleo Legs - Base Light Version (767)
    Retracts Sequencer - ASSAN Adjustable Retract and Door sequencer w/Display
    Servos - HXT900 9g / 1.6kg / .12sec Micro Servo x13
    Strobe Light Controller - Arduino Nano V3.0 Microcontroller Board
    Battery - Any brand 3s 4000mah - 6000mah Range of Lipo

    Control Surfaces as per channel on the receiver
    I've throw in some other redundant add-on goodies that won't be of much help in a model in this scale, but it will make it look even more realistic! (Items 5,6,7,8)
    1 - Ailerons
    2 - Elevators
    3 - Throttle
    4 - Rudder coupled with Nose gear steering
    5 - Retracts with Door open and close sequencing
    6 - Flaps (Fowler flaps identical to the real A350)
    7 - Spoilers
    8 - On-Off Navigation lights

    Other relevant information
    -Model will be build out of Blue Foam and EPS ,after which it will be fully fiberglassed
    -Model will be painted with Singapore Airlines livery
    -I have also started a duplicate build-thread in Rcgroups to gather inputs from other fellow builders to aid this massive project:
    Build Log A350 70mm EDF 1:40scale scratchbuild RC Airliners (Commercial, Cargo, Troop Carrier)


    I have set myself a modest dead-line for this project of 1 year as i have other commitments on day to day basis. Started in Early September 2014 this project will end on Early September 2015. Anything earlier will be a bonus!

    Enough said, let the scratch-building begin!

    Attached Files
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    #2
    Month of September 2014

    So far,what I've done in the month of September 2014 was getting ready the some basic preparation such as drawing out new plans on Autocad. The actual A350-900 plans was taken from Airbus's website and i spent over 3 weeks on heavy editing to ensure the main components such as the Retracts with doors and the 70mm Changesun 70mm EDF fits nicely and to scale.

    The most important part now is to tackle for now will be getting the retracts to swing in and out with the gear doors opening and closing without any issues of space constraints or restrictions.

    In the past, to figure out the CG for every new scratch-build plane i've build. I use to have a link to a website where it scans the entire plan-view area and will give a good gauge on the actual CG location. But unfortunately the website either shifted or closed down. My new method now is to build scaled down chuck glider and use trial and error to find out the new CG by tossing it straight and level in the air and achieve a good glide-ratio without stalling or being nose-heavy.

    Attached Files
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      #3
      This is Model A350 Chuck-Glider at 1:200 scale (35cm wingspan). I gave the wings slight camber, with 5° dihedral and twisting the either sides of the wings to give a straight and level flight.

      The CG was found to be at the "Sweet-Spot" i've earlier estimated.

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        #4
        I've started working on the strobe lighting effect not too long ago.

        The Arduino Uno Board is chose use to program the lighting effects as i have much more versatility in determining the delay and frequency of each strob. The Arduino Nano Board will be used in the A350 as it is much more compact and lighter.

        I've been watching different airliners such as A380, A320 B777 at night with different types of pulse-pattern.Honestly, I do not know which type of Strobe patterns the A350 will use. Do anyone know?, it would be of great help!

        I have came up with 2 types of pattern so far
        1st pattern- White strobe twice, delay 500ms , Red strobe, Delay 500ms. (One cycle in 1 second)
        2nd pattern- White strobe twice every 1s and Red strobes once every 1.3s (Both lights run independently without a defined pattern)




        Attached Files
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          #5
          I have found how exactly the A350 blink sequence looks like.

          It is similar to my "stobe effect 1" where it goes:
          white strobe flash x2 followed by anti collision lights flash x1

          I'll just need to make minor adjustments accordingly to change the flash-timings to match the real thing.

          Note
          -There are 2 anti collision lights,one on top of the fuselage,one at the bottom
          -There are 3 White strobes , 2 at each wing tip pointing forward and one at the rear of the fuselage

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            #6
            Programming a Gear-Door Sequencer

            Normally handling projects this size,It would be almost with certainty there will be some roadblocks ahead.

            I just bump into one huge road block just recently and took 2 weeks to solve it.

            I've ordered an Assan Gear-Door sequencer a few months back (see pictures below) ,plugged in the retracts and servos and it did exactly what it's suppose to do. But after a few runs, the Sequencer just blacked-out on me, everything stopped working. I re-traced back my steps and re-checked all voltages levels given are appropriate and wires connecting to the correct pin and all seems right. i guess i could have end up with a faulty equipment...

            I ordered another Assan Gear-Door sequencer and waited for it to ship to my home, this time with utmost caution, triple checking every wire and connections , it went dead on me again after a few runs! , not wanting to order my 3rd piece, i decided to go the extra mile and program my Arduino Uno to do exactly what the Assan Gear-Door Sequencer does except the part where i have to flick the switch 3 times to arm.

            Programming also gave me full versatility to adjust my servo-travel, servo sweep delay and door open delay timings. Anybody who owns Arduinos at home and wish to give my code a shot, do let me know in this thread,i'll be more than happy to share.

            Theres a thread i've been reading through to seek some help but found out that most guys there are either having problems understanding the manual or finds the "arming" switch quite unesscessary:


            Thankfully , now that the gear-door sequencer ,lighting and other electronic issues are resolved, i can now move on to the actual scratch-building phase.

            Here is my video on my Arduino-Gear-Door Sequencer.


            Attached Files
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              #7
              Finalizing the Door-Sequencer

              One person in the RcGroups forum shared a link regarding a Gear-door sequencer. http://www3.towerhobbies.com/cgi-bin...P?I=LXCJE0&P=8

              I should have got this from the beginning as it is light, come with unique specifications and most importantly, reliable. But given my current circumstances, i'm close to finish with my gear-door sequencing programming so i'll make do with my Arduino gear-door sequencer.

              I've saw a great feature to have to add on into the sequencer, which is to lock the steering when the gear is retracted. It'll save unnecessary current draw as it will coupled with the rudder servo and also to avoid mechanical jam which can be annoying.

              With great enthusiasm, i quickly wrote a few more programming lines and upload into the board.

              Here are the results shown in the video.



              Here is my own gear-door sequencer board lay-out , I've took half a day to design and soldered on all the components on the stripped copper board.

              The whole circuitry isn't that complex to make, it consist of a 2 transistors and a few resisters. Rest are just jumper wires soldered to the different pins of the Arduino board. Next is to pre-positioning the male pins on the copper board to fit the female pins on the Arduino and simply pushing the 2 boards together to lock for compactness. The overall thickness is no thicker than 2cm.

              Attached Files
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                #8
                Above link to the Gear-door sequencer is broken.

                This is the correct link.
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                  #9
                  Hot Wiring Templates

                  My next update,

                  I have printed out the hot wiring templates drawn on AutoCad to A4 papers. The printed templates are than double checked by using a ruler to confirm it's actual dimensions and it turns out that the accuracy is spot on as far as a naked eye can see. This is crucial as there will be some areas in the fuselage, such as the retractable landing gear will have only +/- 2mm (1/16") of freedom when kept in the bay.

                  The printed templates are transferred onto a harder cardboard material as it can withstand higher temperature without burning holes in it.

                  The Cardboard is first wetted with 50:50 whiteglue (this depends on different type of whiteglue brands) to water ratio to keep the viscosity just right so that the ink won't smudge on the printed paper at the same time allowing the glue to be easily spread across the large cardboard surface. Templates are left to dry in the sun after which will be cut out piece by piece.

                  A350 chuck glider put side-by-side to show scale.

                  Attached Files
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                    #10
                    Building the Fuselage

                    I always like to start building the fuselage first from the nose to the rear, unless it is a flying wing! In a more technical point of view, building the fuselage first especially for Airliners is crucial as the Wing's construction such as carbon fibre spars and Retracts depends on several reference points on the fuselage. (More on this at the later part of the build)

                    The shop that sell blue foam comes in 4' x 2' x 2" pieces. I've bought one piece of it and the volume of foam isn't enough to build the whole fuselage of the A350(this was done intentionally). As a foam-saver while trying to save the environment (yeah,right), With the same volume of foam,i've pre-arrange the block of foam into that rectangular overlapping shape (is there a name for this?) to leave the middle hollow so that i have a bigger diameter block compared to a solid piece of foam.

                    Using the pre-cut templates in the previous post, i started with nose first. Showing step by step from a piece of solid block to a nicely sanded nose. After the exterior is done. I cut the nose into 2 and subtract foam within to make space for the Retractable nose gear.

                    The challenge for this part will be building the hinges onto the gear door that will actuate in a particular motion as the gear door won't be hinged directly to the fuselage due to the curvature of the door piece. (See Nose Wheel Autocad picture) . This is reference to the real A350 nose gear doors.

                    Attached Files
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                      #11
                      Hi, are you going to put a download for the plans?

                      Comment


                        #12
                        Hi MrDepron,

                        Of course, will be happy to share.

                        Do note my Plans are still under refinement as i go along with this build thread so this won't be the final version.

                        PDF: (If you want to print to scale, you have to do some scaling which is bit tedious)


                        DWG: (I'll recommend you using Autocad to print as it is very accurate)
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                          #13
                          I can help with the improvement.

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                            #14
                            If you want i can try a pusher version or a slope soaring with your plans

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                              #15
                              Please do and feel free to edit it in anyway you like , share the improvements that you've made and update us with your progress.

                              By the way, if you are making a slope soaring version, do not follow the carbon fibre dimensions in the plans as it will be an overkill and heavier. Go for something smaller will be better like say 5mm Solid Round Carbon Fibre Rod. The rest is up to you
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