Flea style "Piojo Flying MiniBike"

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by FritzW, Oct 26, 2015.

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  1. Oct 26, 2015 #1

    FritzW

    FritzW

    FritzW

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    With so many flying motorcycle ideas popping up on the Modern day "motorcycle of the air" aircraft class? thread, and not getting much beyond the "concept art" stage, I thought I'd start this thread to try and zero in on just one of the ideas and try to move it forward.

    This version would be more of a flying minibike than a flying motorcycle. A safe, very simple, inexpensive fun flyer. Something that could be built in a few months by an inexperienced builder who has limited cash, tools, space and free time. The more it could it could fold up and/or come apart for transportation and storage the better.

    So far the idea is just a simplified HM-14 with the wing gap of the HM 360 so the pilot can walk between the wings and get on it like a motorcycle.

    Flygande_Loppan_500px.jpg + HM 360_380.jpg + FleaFormula.jpg = El Piojo 15.jpg


    Two big challenges I see right off the bat: (any advise/suggestions welcome)
    1) I don't know squat about Mignet Formula design or tandem wings.
    2) I'm not sure how the mono-wheel is going to work out on such a short coupled airplane, but I REALLY like the simplicity.
     
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  2. Oct 26, 2015 #2

    Riggerrob

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    Forget about the mono-wheel.
    Instead, install 2 or 3 wheels and keep the geometry similar to a regular motorcycle. Put maybe 40 of the weight on the nose wheel and 60 percent on the mainwheel. Install the main-wheel 17 degrees aft of the center-of-gravity .... similar to main-wheels on Tri-geared airplanes.

    Wheel diameter is determined by the weight and the size of ruts in your runway.

    Install a skid or small tail-wheel under the rudder post. The tail-skid's only function is to prevent the rudder from dragging on the runway.
     
  3. Oct 26, 2015 #3

    Sockmonkey

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    If you do go monowheel, make sure the wheel is ahead of where the center of mass is without the pilot or your prop goes in the dirt when you dismount. That means the tail wheel will have to take some some load when mounted rather than just being there to prevent dragging. Shouldn't be a significant change is weight and complexity though.
     
  4. Oct 26, 2015 #4

    erkki67

    erkki67

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  5. Oct 26, 2015 #5

    Victor Bravo

    Victor Bravo

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    If you use the things that have been shown to be safe by the Pou community over the last 50+ years, you'll be in a reasonably safe area. If you wanted to be a Boy Scout about it, make a quick and dirty 20% size R/C version and fly it 8 or 10 times at different CG locations. If you come up with an ideal CG on the model that is pretty close to the CG recommended by the full-scale Pou community (25% of the "total chord" between both wings IIRC), then use that as the starting point with a fair amount of confidence.

    The mono-wheel will work out FINE. Trust me. Understand that it has advantages and disadvantages just like any other design choice in any airplane. Trust your gut (and a couple of glider guys' guts like mine and Topaz' and maybe even Autoreply's), that the mono-wheel is a very good bargain for this particular aircraft usage. In other words, the simplicity, weight, cost, etc. are worth the downside in this application. Besides, this won't be a true mono-wheel, you will have an airplane with four wheels on it... but three of them will be small, with only one "main" wheel).

    IMHO Put the main wheel about six inches behind the rear CG limit. You do not want a "taildragger" mono-wheel in this application. Find youtube videos of the lovely old Schweizer 1-26 glider most of us cut our teeth in. Instead of the noisy nose skid, install a heavy duty rollerblade wheel, shopping cart wheel, or other moderate duty small wheel a couple of feet forward of the main gear. Make sure you have six or eight inches of propeller clearance with the nosewheel on the ground. If you want to get fancy and steer the little nose wheel with the rudder then fine. If not, then don't worry about it right this second. If you have prop last on the rudder you can do without it on the first version. Then put two small rollerblade wheels on the wingtips, on eight or twelve inch fiberglass rod "sticks" just to keep the tips out of the dirt.

    Granted, with a short coupled plane like this, the airplane is not going to act like a railroad car. Dragging a tip through a bush will spin it around. So what? The Fauvel gliders have dealt with this for decades. Putting the wheel behind the CG is about all you can do at this stage, short of a full-blown tricycle gear at the cost of 50+ pounds.
     
  6. Oct 26, 2015 #6

    erkki67

    erkki67

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    The shortest Mignet I'm aware off;
    image.jpg
    There are other fleas around short as well, like the Butterfly and Romibutter.

    Rki
     
  7. Oct 26, 2015 #7

    RUSTY

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  8. Oct 26, 2015 #8

    don january

    don january

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    I think the consept is awsome and like a motor bike you use your legs when parked, throw the coals to it and your legs keep it stabilized intill airborn. Way Cool
     
  9. Oct 26, 2015 #9

    rtfm

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    Good luck with the design. I wish you every success - and a lot of fun in the process.
     
  10. Oct 27, 2015 #10

    cluttonfred

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    I think you're on the right track, Fritz, and I would vote for less is more in about every aspect of the design. That includes leaving out the ailerons and I would definitely not put ailerons on a pivoting wing, so if you want full three-axis controls then the front wing should be fixed. See the Lacroix de Nazaris Autoplan in previous Mignet discussions in this group or on pouguide.org.

    2485.jpg

    For absolute simplicity, why not put the wheel ***at*** the CG when level (so it's slightly back if sitting on the tail and slightly forward if leaning on the nose)? Add a front skid to keep the prop clear of the ground when you rock it on to the front skid on landing, much like Mike Sandlin does with his Bloop, and that's your brake!

    [video=vimeo;136009914]https://vimeo.com/136009914[/video]
     
  11. Oct 27, 2015 #11

    lurker

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  12. Oct 27, 2015 #12

    bmcj

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  13. Oct 27, 2015 #13

    FritzW

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    I can understand a monowheel on a sailplane where the aileron is 20' from the lateral axis. But this thing would be so short coupled (aileron ~5' from the lateral axis) you might not be able to raise the wing until you had some pretty good speed. The pilot couldn't afford to have his feet off the rudder pedals while the take off run started, like a motorcycle starting from a stop sign.


    Why can't the front wing pivot and the Cosandey flaps work as elevons?
    HM_VC_10.jpg ...there are 200+ threads on the HBA that discuss Cosandey flaps that I haven't begun to read yet, the answer is probably there somewhere.
     
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  14. Oct 27, 2015 #14

    Hot Wings

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    It will just be more like a motorcycle that low sides after dragging a peg - except for the abrasion that results. What's not to like about this?

    It can. That's exactly how the reflexor on the Q's works.
     
    Last edited: Oct 27, 2015
  15. Oct 27, 2015 #15

    cluttonfred

    cluttonfred

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    Ah, but in a Flying Flea the rudder is connected to the stick or yoke and you steer it like a car. There are no rudder pedals so you absolutely could use your feet to hold yourself upright at first, just like a motorcycle!

    Cosandey flaps are really just big trim tabs which can be used which can be used together for pitch trim and one up, one down to dial in a fixed amount of "aileron" for conventional crosswind approach. You may find that ailerons on the rear wing, which is less highly loaded than the front wing, may not be as effective as you'd like.

    Note that most Mignet types by Mignet himself and others actually use conventional gear and get by fine even in crosswind operations, most without Cosandey flaps. For a light design like this one, with the benefits of the monowheel gear to reduce the likelihood of a ground loop, I think you'd be just fine with two axis controls.
     
  16. Oct 27, 2015 #16

    addicted2climbing

    addicted2climbing

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    Fritz,

    Can i get a solidworks copy of the Briggs motor, PSRU and prop you have in your Assembly file? I think I have the same human model as you that I downloaded of Grabcad. I want to do a quick configuration of something i have in mind. PM me with your email and I will set up a dropbopx folder to share files.

    Take care,

    Marc
     
  17. Oct 27, 2015 #17

    Hot Wings

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    It's a download from GrabCad.
     
  18. Oct 27, 2015 #18

    FritzW

    FritzW

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    So is the prop. It's a scaled up model airplane prop.
     
  19. Oct 28, 2015 #19

    addicted2climbing

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    Thanks guys. I found the files on Grab Cad
     
  20. Oct 28, 2015 #20

    bifft

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    Why couldn't you use ailerons on the rear wing to get full 3-axis control? Doesn't the front wing pivot provide the pitch control?
     

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