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Thread: Armin-style flying wing - introducing the "Cheap Armyr"

  1. #1
    Assault the sky SecretSpy711's Avatar
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    Armin-style flying wing - introducing the "Cheap Armyr"

    Here's my latest project. I was so impressed with the cheapness/quickness/stiffness of Ed's building method (ExperimentalAirlines) that I thought it was time to build a flying wing in that style. It's not finished yet but here is my progress so far.

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    47" wingspan, 440 sq. in of wing area. I expect the AUW to be around 2.7 lbs with full FPV gear.

    Power system will be a Turnigy Park480 1320kv motor (275 watts) with a 8x4.5 folding prop, running on two 3S 2200's in parallel.

    So, since I used the Armin build method, with elements taken from the Deep Reaper and Zephyr designs...

    I think a good amalgamation for a name would be "Cheap Armyr!" There's less than $10 wrapped up in the airframe, including the spars. I really like how it's turning out.

  2. #2
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    Looks nice ...Please post some dimensions of the wing.

  3. #3
    HeliMedic ColoradoFlightMedic's Avatar
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    Nice work! I really like what Ed has pioneered... that airfoil is genius! I'll admit though, I've struggled getting my mirrored pairs to match up, therefore I have a small air force of planes with a 30" wingspan Any tricks to get a nice taper to those wings?
    Brooks, N7BLD

  4. #4
    Crashing Vitamin J's Avatar
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    Nice! That thing looks super clean. I built one like that awhile back but scaled down to 38," it flew awesome. I'm gonna have to build a bigger one like that.

    I bet it will fly amazingly, that type of construction is super light and stiff. Be careful though it'll take a few crashes, but anything big will crease the foam and then it will flop around like spaghetti.

  5. #5
    Assault the sky SecretSpy711's Avatar
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    11" root chord, 7" tip chord (not including ailerons, I added those separately). 35 degree leading edge sweep. Center section is 8" wide.

    @ColoradoFlightMedic, all I can say is just take your time and be careful with the measurements. You'll still end up having to trim root and tip. If I did it over again, I would've also tapered the "spar foam" width. Right now it is a constant 1.75" wide. I've also noticed that the airfoil sorta ends up with a flat spot near the LE, so the next one I might try to fix that.

    There's a post here on RCGroups that shows what the flat pattern looks like. I didn't follow it exactly, as I started building before I found that thread, but it's nearly identical. Templeton89 had a good idea for using a Simpson Strong Tie as a motor mount.

    This is the layup I used for the thickness-taper. The center layer is split to allow for a spar channel but I'm not using one along the length -- just through the center section.

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    -----
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    It left some gaps, so the next one might be more like this, I think it would lay down more cleanly. This is how real aerospace composite parts are tapered anyway:

    -------------
    --
    ------
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    -------------

    I don't plan to crash it, but maybe that's where the spar-channel will come in handy later to stiffen it back up :-)

    Also, we'll see where I have to place the batteries for CG. It allows a few different placement configurations but I wish I had made the center section slightly wider to fit 2 batteries end-to-end laterally.
    Last edited by SecretSpy711; 30th March 2012 at 12:21 PM.

  6. #6
    FPV - Fly Low airbagit13's Avatar
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    Nice, very clean build.
    FPV is not a crime!

    executiveprinters.com
    printingplusfl.com

  7. #7
    Assault the sky SecretSpy711's Avatar
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    Another thought for a future build...better control of the actual airfoil shape. Most flying wings prefer to have an airfoil with some reflex (aft section turned slightly upwards.)

    Instead of removing ALL of the paper on the upper surface, I might try leaving some paper towards the back end, and also de-papering a similar-width strip on the bottom surface. If anyone tries this before I do, let me know how it works!

  8. #8
    Assault the sky SecretSpy711's Avatar
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    Last edited by SecretSpy711; 29th April 2012 at 05:05 PM.

  9. #9
    I see you... Derrick's Avatar
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    The landing technique is pretty awesome... hope no tree huggers are offended It looked better in real life than on the video though.

  10. #10
    Crashing Vitamin J's Avatar
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    Nice dude, congrats on a successful flight! You guys are gonna have to show me that flying site as well!

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