Flea style "Piojo Flying MiniBike"

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

Help Support HomeBuiltAirplanes Forum by donating:

  1. Aug 27, 2019 #421

    Tiger Tim

    Tiger Tim

    Tiger Tim

    Well-Known Member

    Joined:
    Apr 26, 2013
    Messages:
    2,846
    Likes Received:
    1,588
    Location:
    Thunder Bay
    Fritz, if you haven’t binned the whole concept yet maybe just make a bunch of RC test articles and find out for real what works and what doesn’t.
     
  2. Aug 27, 2019 #422

    poormansairforce

    poormansairforce

    poormansairforce

    Well-Known Member

    Joined:
    Mar 28, 2017
    Messages:
    610
    Likes Received:
    131
    Location:
    Just an Ohioan
    You need to look at it again and follow it through its motion. I don't know if the throw amounts are correct or if the forces are viable....
     
  3. Aug 27, 2019 #423

    poormansairforce

    poormansairforce

    poormansairforce

    Well-Known Member

    Joined:
    Mar 28, 2017
    Messages:
    610
    Likes Received:
    131
    Location:
    Just an Ohioan
    In Sockmonkey's original drawing the angles were too steep but it works after he made the pushrods 45°.
     
  4. Aug 27, 2019 #424

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,546
    Likes Received:
    3,161
    Location:
    Las Cruces, NM
    Mach flow through the gap in the split wing might be a problem.


    That makes the most sense and sounds like the most fun.
     
  5. Aug 27, 2019 #425

    Dennis K

    Dennis K

    Dennis K

    Member

    Joined:
    May 23, 2014
    Messages:
    7
    Likes Received:
    3
    Location:
    Portsmouth, NH USA
    This control method pivoting the wing halves independently as elevators and ailerons has been successfully used on R/C model slope soarers for years. It's called wingerons or pitcherons depending on the number of functions utilized and is similar to the arrangement used for a butterfly tail. Here's a Utube video example in action (notice the degree of control).
     
    Last edited: Aug 27, 2019
    Sockmonkey likes this.
  6. Aug 27, 2019 #426

    erkki67

    erkki67

    erkki67

    Well-Known Member

    Joined:
    Feb 18, 2010
    Messages:
    1,532
    Likes Received:
    164
    Location:
    Romont / Fribourg / Switzerland
    Perfect illustration
     
  7. Aug 27, 2019 #427

    erkki67

    erkki67

    erkki67

    Well-Known Member

    Joined:
    Feb 18, 2010
    Messages:
    1,532
    Likes Received:
    164
    Location:
    Romont / Fribourg / Switzerland
    And as the whole wing is rolled, not much of roll is required max 4 -5 Degrees I believe .

    A big eyebolt would be sufficient to hang the wing at the fuselage king post
     
  8. Aug 27, 2019 #428

    Aerowerx

    Aerowerx

    Aerowerx

    Well-Known Member

    Joined:
    Dec 1, 2011
    Messages:
    4,908
    Likes Received:
    1,320
    Location:
    Marion, Ohio
    I still don't see it.

    Could you possibly redraw with the deflection, using the same dimensions for all the components, and in the proper relationship?

    Another thing I wonder about is that the push-pull force is being applied at an angle to the wing. Doesn't that require a lot more force than if it is at a 90 degree angle?
     
  9. Aug 27, 2019 #429

    Victor Bravo

    Victor Bravo

    Victor Bravo

    Well-Known Member

    Joined:
    Jul 30, 2014
    Messages:
    6,005
    Likes Received:
    4,808
    Location:
    KWHP, Los Angeles CA, USA
    I had a wingeron slope glider. Worked fine, but it required a very large steel rod to pivot the wings, and serve as the main center section spar. I am guessing that the same type of steel rod or heavy tube would scale up to be somewhere around 75-100 pounds on a full-size man-carrying aircraft where it would be expected to take 4G while still not bowing or bending the rod (and locking the roll control). Seems like it would be a high price to pay. Any one of you high brain function types care to validate or de-bunk that 75 pound wild guess? For sake of discussion, let's say you have an 18-20 foot wingspan and a 600 pound gross, 5 inch thick wing section, and you cannot afford for the pivot tube to bend more than a couple of degrees.
     
  10. Aug 27, 2019 #430

    erkki67

    erkki67

    erkki67

    Well-Known Member

    Joined:
    Feb 18, 2010
    Messages:
    1,532
    Likes Received:
    164
    Location:
    Romont / Fribourg / Switzerland
    The main load is going over the rotation point of the wing fuselage connection and at the wing strutt attachment.

    So the control rods can have about the same size like in standard flea.
     
  11. Aug 27, 2019 #431

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,656
    Likes Received:
    431
    Location:
    Flint, Mi, USA
    Ok, here ya go.
    [​IMG]
    The amount of force the pilot needs to apply doesn't seem to be that much, but the proportions and exact positioning can be tweaked a bit.
     
  12. Aug 27, 2019 #432

    Victor Bravo

    Victor Bravo

    Victor Bravo

    Well-Known Member

    Joined:
    Jul 30, 2014
    Messages:
    6,005
    Likes Received:
    4,808
    Location:
    KWHP, Los Angeles CA, USA
    You know what, they're right. The forces will be far less than a cantilever wing. But there will still be bending loads in the center.
     
  13. Aug 27, 2019 #433

    Topaz

    Topaz

    Topaz

    Super Moderator

    Joined:
    Jul 30, 2005
    Messages:
    13,628
    Likes Received:
    5,279
    Location:
    Orange County, California
    Just seems like a needless development risk that offers little perceptible benefit over simply putting ailerons on the rear wing.

    Looking at this, the "benefit" is a reducing the roll-control system by 2-4 pullies and about six feet of cable. The "cost" is breaking the spar at the middle of the span, large pressure leaks through the centerline when rolling - with the attendant increase in induced drag, and potentially wrenching control forces on the stick in gusty conditions.

    I just don't see that it's worth it, myself.
     
  14. Aug 27, 2019 #434

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,656
    Likes Received:
    431
    Location:
    Flint, Mi, USA
    The center is supported by the A-frame struts.
    There are other benefits. Less twisting force on the fuselage while banking. The downwash from the fore wing increases the lift on the aft wing. That's how fleas can stay level while climbing and descending. That means the half of the fore wing that deflects it's trailing edge down to increase it's lift will also increase the lift of the aft wing on that side so both contribute.
    The aft wing being shorter also means that aft ailerons would have much less roll authority.
    Honestly if you don't want to split the fore wing, just stick full length flapelevons on the fore wing instead of the rear one. They will still do all the things you need.
     
  15. Aug 27, 2019 #435

    Aerowerx

    Aerowerx

    Aerowerx

    Well-Known Member

    Joined:
    Dec 1, 2011
    Messages:
    4,908
    Likes Received:
    1,320
    Location:
    Marion, Ohio
    Thank you, but I still don't get it.

    As you tilt the control stick to the left, the right ball joint goes HIGHER than the neutral position, as you show. So how can it pull DOWN on the right wing?

    Unless there is an angle at first where it starts to pull down, stops, and then with further stick travel, starts to push up. NOT a good idea, IMHO.

    And, as Topaz said. Needless development. Aren't there some split wing aircraft that already do this? And it is certainly possible to do this without ball joints.

    [Edit] Ah, I think I see what you are doing. In the neutral position the pushrods are supposed to be exactly at 45 degrees?? You are taking a known design for a elevon mixer and making it bigger. The problem is that you would have to use steel tubing for strength. This will be heavy, and I also think that such long unsupported pushrods will flex and possibly lead to disastrous wing flutter!
     
  16. Aug 27, 2019 #436

    poormansairforce

    poormansairforce

    poormansairforce

    Well-Known Member

    Joined:
    Mar 28, 2017
    Messages:
    610
    Likes Received:
    131
    Location:
    Just an Ohioan
    Let me be clear, I'm not advocating or rejecting this idea. I just wanted everyone to be on the same page. The forces due to the angles will be different, that is certain
     
  17. Aug 27, 2019 #437

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,656
    Likes Received:
    431
    Location:
    Flint, Mi, USA
    Like I said, if you want ailerons instead of a moving wing then the ailerons should be on the fore wing.
     
  18. Aug 28, 2019 #438

    Topaz

    Topaz

    Topaz

    Super Moderator

    Joined:
    Jul 30, 2005
    Messages:
    13,628
    Likes Received:
    5,279
    Location:
    Orange County, California
    That's actually the far better idea, if one simply can't handle ailerons on the rear wing for some reason. Rutan tried this on one of the EZE prototypes and had very poor results, but then the canard on the EZE's was a very small surface, relative to the wing. It would take a lot of calculation and probably some additional testing, but the fact that a "flea" derivative has much larger front wing might make this possible. You'd still have the added complexity of a mixer, but that's an individual choice.

    All this said, I'd personally just put ailerons on the rear wing.
     
  19. Aug 28, 2019 #439

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,546
    Likes Received:
    3,161
    Location:
    Las Cruces, NM
    Making a mixer isn't an issue. The issue is weather or not it makes sense to put a split wing on a Piojo.

    What would be the advantage?
     
  20. Aug 28, 2019 #440

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,656
    Likes Received:
    431
    Location:
    Flint, Mi, USA
    If you wanted to stick with just two-axis then a split wing gives that with a single control system. Plus, it gives an easy way to fold the wing just by unhooking the outer struts since the wing is already in two halves.

    Rear wing ailerons only make sense if you make them elevons and have the fore wing be fixed.
     

Share This Page

arrow_white