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Thread: ZII: Project Hello Kitty

  1. #11
    Instructor Pilot
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    Kev if you actually attempt this let me know I can help you get it strong enough and keep it lite.
    Hitting Cg and fuel on the CG will be your largest hurdle.

  2. #12
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    This is awesome!!!!

  3. #13
    Cor blimey, guv'nor!
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    Thanks for all the comments guys!

    Yes, I may well be a little mad, but if this comes off, it could well be something pretty special. The first ever jet powered r/c wing and the first ever FPV piloted jet. The sound and the smell alone will make this epic!

    BCSaltchucker, a tandem flight with Yves “Jetman” Rossy would be pretty cool, but I'd probably leave that piloting role to someone more qualified than me.

    I'm well converse with gas turbine engines. I've built and fly a gas turbine helicopter, so the power plant aspect of this build is the very least of my concern.

    I'm a notoriously slow builder however, primarily due to a lack of time and really only having a 1/2 day a week (at best) where I have access to quality workshop equipment and a second pair of hands to help. As a result, I actually started this quite a few months ago and so have progressed quite some way already.


  4. #14
    Cor blimey, guv'nor!
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    Flat out, the turbine consumes 100ml of fuel a minute. They're thirsty beasts, but naturally I won't be flying flat-out all the time. That said, the twin fuel tanks will hold 800ml, so at least 10 minutes of spirited flying should be assured. This won't be a 'long range' craft, but I'm confident it'll climb faster than any other FPV plane, so if it all comes together, gunning for an altitude record might not be out of the question.

    As Chris has alluded to, my biggest concern (by far) with build is with the CG. The design, shape and placement of the twin tanks have been done in such a way that when either full or empty, the ZII's CG doesn't change. Like with everything else on this build, this has been modelled in SolidWorks.

    My concern however comes from the CG changing due to the movement of the fuel, and so to try and help here, I'm going to have to employ some sort of electronic stabilisation. The fuel tanks have baffle plates (again on the CG line) to minimise the effect of 'fuel slosh', but this is my biggest and in truth, only, concern with this build.

    The fuel tanks have been made out of folded and soldered tin-plated steel. It took me many iterations to get this right, but as with a great deal of this build, they're now done.











    Last edited by Ian Davidson; 23rd July 2012 at 05:42 AM.

  5. #15
    Cor blimey, guv'nor!
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    To make way for the fuel tanks, the original locations for the servos had to be moved out. Pretty simple really (unlike carving out the recess for the actual fuel tanks, which took hours!), but this time I made the new servo holes angled so parallel with the ailerons. It just seemed more logical.





    Last edited by Ian Davidson; 23rd July 2012 at 05:43 AM.

  6. #16
    Pilot Blizzard1287's Avatar
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    Ian, have you considered lining the fuel tank with some sort of bladder bag? If you pump the fuel into the bag you'll have a constant fuel supply and it wont pool to the front or the back if your doing anything but level flight. Also should keep it from sloshing around (or at least more contained) with those metal support beams you have in there. Idea?
    Last edited by Blizzard1287; 22nd July 2012 at 04:42 PM.
    Some fly for attitude, others for altitude

  7. #17
    Just dog tired. Wearyman's Avatar
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    Quote Originally Posted by Blizzard1287 View Post
    Ian, have you considered lining the fuel tank with some sort of bladder bag? If you pump the fuel into the bag you'll have a constant fuel supply and it wont pool to the front or the back if your doing anything but level flight. Also should keep it from sloshing around (or at least more contained) with those metal support beams you have in there. Idea?

    I think Blizzard is right. Based on what I know of REAL Airplanes, the fuel tanks are always lined with a bladder bag that starts out with no air in it so that fuel pressure is always slightly positive. I've seen a few RC jets and they use bladder bags too. (One guy who posted his ramjet plane here uses old hospital IV fluid bags for fuel bladders.) The bag itself resists the fluid sloshing and helps keep the fluid stable in flight.

  8. #18
    Navigator ChrisG's Avatar
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    Awesome! I own a Jetcat 160 powered Eurosport. I've often thought about a turbine glider for FPV but Unfortuneately our governing body for models here in Oz strictly bans the fpv/turbine mix

  9. #19
    Cor blimey, guv'nor!
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    Quote Originally Posted by ChrisG View Post
    Awesome! I own a Jetcat 160 powered Eurosport. I've often thought about a turbine glider for FPV but Unfortuneately our governing body for models here in Oz strictly bans the fpv/turbine mix
    Nice plane!! I'm sure the authorities here would have something to say about what I'm planning, but there are no distinct rules against it. To the best of my knowledge, not one has ever FPV'd a jet anywhere!

  10. #20
    Cor blimey, guv'nor!
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    Blizzard and Wearyman, I very much agree you guys, a bladder tank would be ideal! However, the problems I foresaw with this were, 1. how do you get bladder tanks even approaching the shape of those I have without being very wasteful on space/fuel capacity and 2, how can you get two to work in perfect tandem? I'm definitely open to ideas though, as although the tanks are 100% on the CG line, the movement of the fuel is my one-and-only concern with this build.

    I did a lot of tests with subtlety different tanks designs and ruled out having dual feeds in a 'Y' to the fuel pump, because as soon as one of the feeds had a marginally greater resistance than the other (e.g one of the pipes was bent differently, or one of the clunks gets a tiny bit clogged) then it simply sucked all the fuel from the tank of least resistance. Therefore I decided on a single feed from one tank and both tanks plumbed together as one.

    As you see in the photos, I had to use a 10mm brass tube to connect them, as with just a simple fuel pipe, the tank I was draining the fuel from would be half empty before the other one even began to drop. As I have it now, they both drop at the same rate, which is ideal.

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