Glider Performance Limitations or Requirements

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by jedi, Sep 24, 2018.

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  1. Sep 24, 2018 #41

    jedi

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    Not my area of expertise but I understand DARs are limited to certain types of aircraft. Most all are airplane, some rotorcraft, etc. Few Glider.
     
  2. Sep 24, 2018 #42

    narfi

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    I gave the link. It is registered with the FAA as a glider. What is your question?
     
  3. Sep 24, 2018 #43

    Hot Wings

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    Agree - They do not have a specific LSA category or class to define a motor glider, glider, gyro, or lighter than air. They are all LSA.

    My reading of the regulations is that a powered glider is a sub class of glider and gliders are limited to 120kt Vne while a pure airplane only has a cruise speed limit Vh of 120 Kts. It would then follow that a glider with an engine, 'powered glider' in FAA speak, is functionally different than a regular light sport airplane and this difference is recognized by the regulation. There are also provisions granted to LSA gliders that also transfer to powered gliders, such as retractable gear and feathering props.

    The ASTM standards, per the NPRM, also have a separate standard for gliders that includes standards for powered gliders. There is nothing in the ASTM glider standard with regard to wing loading or aspect ratio to differentiate an LSA glider from a 'standard' LSA.
     
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  4. Sep 24, 2018 #44

    BBerson

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    Huh? It says "Glider category" in FAR 61.313 of the Light Sport rules.
    There is no category "rating", as I mentioned. But there is the use of category and class of aircraft for the endorsements.
    The word category and class is in 61.321.
     
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  5. Sep 24, 2018 #45

    Topaz

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    Sorry, I missed your link. Been a very long few weeks at work.
     
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  6. Sep 24, 2018 #46

    narfi

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    Winter is coming, then we can sleep :)
     
  7. Sep 24, 2018 #47

    Topaz

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    Winter is coming, then I typeset all the changes to the California Penal Code, Vehicle Code, Fish & Game Code, unabridged and abridged versions, etc. Besides, the temps will fall down to a brisk 75-80° F here during winter. Who can sleep in such cold? ;)
     
  8. Sep 25, 2018 #48

    mcrae0104

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    Yeah, when he gave an update at OSH (2017 was it?), I recall he we going for motorglider. He does not appear in the FAA registry as a PPL holder.
     
  9. Sep 25, 2018 #49

    BBerson

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    The registry only lists pilots with current medicals, I think.
     
  10. Sep 25, 2018 #50

    Marc Zeitlin

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    Burt designed it to meet the requirements for a Motorglider, and that's how he certified it in the EAB category.

    I believe that it actually meets the certification requirements for span loading for motorgliders, so it's only sort of a stretch.

    Except that Burt does not have a current medical since his heart surgery of 11 years ago (and cannot get one) so as long as he's never applied for a medical and been turned down, he can legally fly a "glider" without a medical. That (along with the original long range requirements he had for the plane) was one of the major reasons for designating the plane as a motorglider.
     
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  11. Sep 25, 2018 #51

    proppastie

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    missing the cord, to have Sq. FT. you need length by width, or cord x span. I surmise the language is such because one includes the fuselage portion of the span when calculating the Sq. Ft. of wing area. But I have been wrong before.
     
  12. Sep 25, 2018 #52

    jedi

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    It is not square feet, it is feet squared. The span, b, can be given in feet or meters and the requirement is 0.62 pounds per span squared in feet or 3.0 Kg per meter squared of span respectively.

    The limitation is not a wing area limitation it is a wing span (actually span loading) requirement. The b is the wing span. The requirement is a function of span, b, squared.
     
    Last edited: Sep 25, 2018
  13. Sep 25, 2018 #53

    mcrae0104

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    You lost me. When is a square foot not a foot times a foot?
     
  14. Sep 25, 2018 #54

    narfi

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    Well 10 square feet could be 2ft x 5ft or any other combo, where 10 feet squared would be 100 square feet, or am I mistaken?


    Edit:
    Wait, was it a riddle?
    When is a square foot not a foot times a foot?
    A: when it's a hoof!
     
  15. Sep 25, 2018 #55

    lr27

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    Span squared is the span times the span. It's not an area. A foot times a foot can be square feet, but it doesn't have to be. Span squared will be the same whether the chord is 1 inch or 6 feet.
     
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  16. Sep 25, 2018 #56

    proppastie

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    The Carbon Dragon is 44 ft span 44 x 44 =1936 If the gross weight is 400 # 400/1936=.207

    The area of the wing platform is 153 ft sq.... 400/153=2.6

    Sorry It does make sense.
     
  17. Sep 26, 2018 #57

    lr27

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    Not sure what you're saying here.

    Regarding span squared loading, it has a lot to do with induced drag and sink rate. Induced drag, at least on a vanilla sort of wing, really doesn't care how much area it takes to get the lift you have. Wikipedia says the gross is more like 335 lbs, so the span squared loading is even lighter. For a 1-26, it's 0.44 or so. (English units as with your calculation.) The sink rate reflects this.
     
  18. Sep 26, 2018 #58

    blane.c

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    So whats everbody's understanding of the number of engines or motors you can have on a motor glider? Is 27 engines and/or motors ok?
     
  19. Sep 26, 2018 #59

    proppastie

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    certified or homebuilt?
     
  20. Sep 26, 2018 #60

    proppastie

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    we are saying that CS-22 calculation is true for the Carbon Dragon Glider, and as you pointed out the 1-26
     

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