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  1. #61
    Building Fool-Flying Noob FoamyDM's Avatar
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    Sep 2016
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    468
    Nice

    The squids did good work, but not soon enough though because my motors are acting all twitchy all of a sudden... rrrg. But I have it working right - according to the bars. looks like more solder work tomorrow.
    FTFC'18 WWII - Team ALLIED FORCES PAGE

    FTFC'18 WWII Projects (Join Us!): Kalinin K-12 | SAM-7 "Sigma" | LPL Flying Sub

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  2. #62
    Building Fool-Flying Noob FoamyDM's Avatar
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    Progress and Trepidation

    After looking through the Lippisch P13a by dr. Looping Looie thread I noticed he used a paper copy to test CG. I thought, "Great Idea!" so I printed the K-12 out on A4 paper, and started cut and folding, here's the result.
    Click image for larger version. 

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    I tested it in the office, testing it in the hallway. Sadly it had a tendency to roll and float upside down. I had only a few "Meh" glides, then added the wing tip rudders, and adjusted... it didn't seem to have much yaw effect at that size I didn't expect much. Then added Aileron Flaps and adjusted, but still wasn't able to stop it from flopping over.

    I was able to learn the CG was narrowed down it's location to 1/8" to 3/8" just in front of the back vertical leg of the spar box.

    It's funny how this is Exactly where the Bomb Bay is.

    But I couldn't manage a consistent glide. It nearly always flopped over, and or spun under. That was pretty cool.

    OK I think I have 2 bad 12A escs and 1 bad 20A escs. They'd power up and go through the beep cycle but throttle up yields twitching. So I spent last night testing, re-flowing., re-soldering etc. Still bad (maybe). So while the solder joints are definitely good, I decided to pull out the un-opened 12A escs from a quad, where I replaced the stock 12A's with 20A Aikons. Soldered up the Bullets, and XT60, shrink wrap and the test on both are solid. I also pulled out a 30 Cheap ESC for the 2812 center motor for the flying Sub. Although I think I might switch up to the C-pack motor as I can set it up with a shaft in front and one in back. lending for perfect motor for propeller or water screw drive from the same source.

    I have a little Time. I will have the water screw shaft in for show. For the air flights. wither way is good for air-worthiness testing.
    FTFC'18 WWII - Team ALLIED FORCES PAGE

    FTFC'18 WWII Projects (Join Us!): Kalinin K-12 | SAM-7 "Sigma" | LPL Flying Sub

    Personal:VF-9 (Robotech), FLITE TEST CARD GAME, Anime X1, Getting my Gremlin(s) Up.

  3. #63
    Old and Bold RC PILOT
    Join Date
    Aug 2016
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    Brisbane, Australia
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    As for you inability to obtain a consistent glide from the paper mock-up I would say that it is to be expected!

    The drag of the plane is far higher than the forward thrust you would ever get from the weight of the craft working through the wing shape.

    What is happening is that because it has such a large cross section and so little weight the drag quickly slows the model to below stall for the wings and then the little weight the model has uses its inherent centre of mass and rolls the plane to put the centre of mass below the lift, centres for stability. The wings are now acting as parachutes,

    The spinning inverted is caused most likely by differences in the parachute like lift from the wings and their aerofoil shape.

    If the paper model can support an increase in weight add some for better glide response or angle the launch in a slightly nose downwards attitude and try to keep the models speed above stall.

    Just a few thoughts,

    Have fun!
    Hopefully making a difference!

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