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A350-900 70mm EDF 1:40scale scratchbuild

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    #31
    I am still working out why i cant post photos.But i am working out the placement of servos.i have already cut out the stabs and wings.And sanded the front edge and added the curve to the wing.I'm considering painting it in Air France colours as the model is not very big and needs SUPER PRECISE painting and detailng.Air France colour is simple,paint the fuse white and add the windows logo and some other details which will be printed decals.All i need to paint is the wings,the fuse.


    Edit:YAY!I MANAGED TO POST A PHOTO!
    I will post the photo of the model later.

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      #32
      Hi viper,do you know the effects created by wing flex?

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        #33
        Hi mrdepron,

        Glad you've enjoyed your trip. Remember to prep your surface of your aircraft well, meaning to sand the cutting lines away real nice and smooth starting from a higher grit sandpaper to a lower grit sandpaper. A good surface will determine how good your paint job will turn out in the end! I've made many mistakes and ugly finishes myself and this time i'll be paying closer attention to the surface of my aircraft too before finishing it off with spray-painting.

        To answer your question on wing flex, i not too sure myself, but i can give some logical answers to how a high wing-flex have an effect on your model:
        1) Lower wing area = less lift and your plane will have to fly faster to prevent from stalling
        2) Higher dihedral = more stability about the longitudinal axis of the aircraft, means it would be harder for the aircraft to bank left and right using ailerons. Normal for gliders to have high dihedral wings for stability and using the rudder to yaw the plane left and right would be preferable in this case.
        3) Wing flexing on a RC plane is normally not that visible , but if you do witness it happening to your model in air, means the wings require more reinforcement spars. On a true account, i had once a flying wing that flex really bad, and the wings starts to vibrate/oscillate on it's natural resonance (like a bird flapping it's wing). The vibration was continuous for a few seconds till the carbon-fiber rod within gave way. I had no control over it's control surfaces during the ordeal and the wings just folded mid-air
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          #34
          Underbelly Construction

          The underbelly , aka: wingbox , was constructed using depron sheets. 1/4" (6mm) depron for the belly ribs and 1/8"(3mm) for sheeting over the ribs.

          The underbelly will eventually house the main landing gears retracts , ESCs and the 3s 5000mah lipo.

          14 Underbelly ribs templates was printed out and was pasted right onto the depron sheet using 50:50 water to white glue mix. The ribs was cut out and hot glued right onto the underbelly of the fuselage. The Pin-point accuracy of the ribs placement is very crucial here as the wingbox will be used as a reference for the wing's construction. It would be undesirable to end up with a slanted wing tilted to one side relative to the fuselage!

          The step by step belly sheeting is shown below. The segments were first built from the middle and the both ends completed last. Once the sheeting is completed, there are small gaps in between each panel which are filled with wall putty.

          The long yellow cardboard was pinned on the fuselage as wire guides for the wire to follow accurately for a good straight and neat cut. Slicing through the thick foam feels like cutting jelly!

          Curious about the fuse weight at the moment, I took it to the weighing machine ,and here are the results:
          Whole fuselage ,inclusive of nose gear: 553grams
          Nose Gear weight: 88grams
          Fuselage without Nose Gear weighs in: 465grams
          The weight is acceptable for me at the moment. My estimated empty weight (purely material only without components) fiber-glassed full air-frame will be about: 1000grams

          Side experiment i've conducted regarding how much additional weight was added when the putty was applied
          Whole fuselage: 553grams
          Whole fuselage with fresh wet putty: 563grams
          Whole fuselage with dried putty: 560grams
          Thus:
          I've added 10grams of wet putty,3grams of water evaporated leaving me with 7grams of dried putty as additional weight.
          So i can give a rough estimate that the putty compound i'm using consist of 70% putty material and 30% water in weight.

          Additional comments
          i've been looking at demondriver's video on foam types,polystyrene vs bluefoam here: http://www.rcgroups.com/forums/showp...&postcount=199
          I totally agree that polystyrene would be the ultimate weight-saver option, infact my fuselage would weight only 553grams/3 = 184grams if it's made out of polystyrene. But the reason for the choice of using bluefoam is that the fuselage is going to be fiber-glassed. Polystyrene cell-structure is widely spaced compared to blue foam ,hence it would soak up much much more epoxy resin which might turn out heavier. Having said that, Polystyrene is still my favorite material to work with,I have build many light foam places using polystyrene + packing tape combination and i find that the easiest to work with ,cheapest, much lighter with most durable option so far.

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            #35
            I changed my mind about a slope soarer. I am going to mount the motor at the nose, the final product will look like that glide below.i just ordered a cheap chinese 2200kv with a GWS 4.5 or 5 inch prop which will give me enough propulsion. I will use my custom battery packmwhich i made from my laptop battery pack. It is a 2 cell 4400mah li-ion. I will try bamboo skewers as wing re-inforcement.There will not be flaps.I just busted up 4 out of 6 servos in the 747 crash. I have just ordered 2 Tower Pro SG 90 9 grams along with the motor. I have a recipe of making my own putty which i will share on my next post.

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              #36
              May I suggest you using a 6x4 or 7x3 inch prop when running a 2200kv motor with 2s lipo. A 5 inch prop will not give you sufficient thrust. A bigger prop also allows you to have more airflow around the thick fuselage, as airliners
              Generally have fat fuselage.

              Trust me on this one. I once too attach a 5 inch prop on the front of a cessna (recommend prop was 8inch). Its flight path was extremely unstable.

              Play around the values using this useful website.http://www.ecalc.ch/motorcalc.php
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                #37
                Thanks viper for the advice.May i know what piano wires you use?Those tettra 1.6mm mwhich i bought from Singapore Hobby is difficult to cut.i had to saw them. They are also difficult to bend.

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                  #38
                  My push rods comes from diaso. Shop sells about 20m length of wires with different diameters.

                  Use the right tools for the right job and you will find doing things much easier. For instance, instead of sawing the piano wire, try using pilers that comes with inbuilt wire cutters. Or if possible, I use a dremel rotary tool with disc cutter blade, cuts thin steel like tofu.

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                    #39
                    I dont remember seeing push rods in daiso.Which section?(eg.handicraft,sewing)

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                      #40
                      I can't remember which section. But it looks something like this , get the steel wire, not the brass. Just uncoil and straighten them and you'll get pushrods.

                      Click image for larger version

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                        #41
                        Ok.Thanks

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                          #42
                          This is what i bought.Diffrent packaging

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                            #43
                            Oh, anyways, thank you for you recomendation. It works great!

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                              #44
                              Reshaping the micro's fuselage

                              Reconstructing the fuselage as the additional 5cm from the fuselage spars made the extra wide body fuselage into a super extra wide body fuselage.

                              The pictures below shows the detail of the fuelage,before and after.

                              Attached Files

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                                #45
                                Hey Mrdepron,

                                I think I know how you end up with the bulge in fuselage the first place which cause your "Extra wide body".

                                Lets use Template E as an example for your fuselage construction. See picture below.

                                If you trim-off the already existing bulge that happens in the first place, it might be not as accurate as before. Assuming if you are going to skin your fuselage with a thin sheet of depron, you need all the ribs to be +- at most 1 mm accurate for the skin to touch all the ribs to maximise area contact between them to ensure proper glue-bond.

                                Fear not! as there are many methods to solve your problem if you do not want to rebuild the fuselage.One of them is try using a long sanding block (Must be straight and flat!) and carefully sand several ribs at the same time length-wise. It should give you good accurate results!

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