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 #21

    proppastie

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    part 103 glider is 155 lb and I do not think they will give a weight exemption, best not to tell anyone if it is slightly over.
     
  2. Sep 24, 2018 #22

    Topaz

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    There is no aspect ratio requirement, especially for E-AB. As I discussed earlier with Jedi (and provided the relevant AC21.17-2a), there is a span-loading discriminator that says, if you're trying to type certificate your powered glider design, which certification standard you must use, either EASA CS-22 (called JAR-22 at the time the AC was written) if the aircraft qualifies as a Glider, or FAR Part 23 if it must be type-certificated as an Airplane.

    None of this applies to E-AB, where the builder gets to decide whether go after an airworthiness certificate as a Glider or as an Airplane, and the FAA gets to decide if they agree with you or not. There are no objective criteria. Basically you have to convince the FAA that your aircraft is capable of operating as a glider, and how you really intend to fly it that way. The farther away from a recognizable motorglider your airplane is (and a Cub clone is pretty far, even with longer wings!), the harder time you'll have convincing the FAA, particularly if you don't already have a Glider rating and self-launch endorsement. Took the guy with the Challenger about two years of arguing before they finally gave in, and there were more guys that never succeeded.

    Trying to use the "motorglider loophole" to fly airplanes without a medical certificate is a possible route. It's just a risky and expensive one.
     
  3. Sep 24, 2018 #23

    proppastie

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    pictures, links, did not know there was one.
     
  4. Sep 24, 2018 #24

    Topaz

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    The reason a Glider rating for motorgliders isn't required under Sport Pilot is that there is no such beast as a "Light Sport Motorglider." A powered aircraft either qualifies as an LSA or it does not, regardless of how long the wings are, and LSA does not have a category for "powered glider." It does recognize unpowered gliders, which I believe require a logbook endorsement to your Sport Pilot certificate, but does not recognize gliders with engines as different from "airplanes." The self-launch endorsement probably still does still apply because it's separate from the pilot's certification, just like a tailwheel endorsement (and comes from the same part of the FAR's). It depends on whether or not the AC or TC defines the airplane as a "Glider". A powered aircraft could have a TC or AC as a "Glider", and would require a logbook endorsement for self-launch even if it also fell within the weight, speed, and other limits that allows it to be flown as an LSA.

    It should be noted that LSA is much more restrictive than the Glider category in the rest of the FAR's. An aircraft with a "Glider" type on the AC can have retractable gear, has no particular speed limitation until you get up to "High Performance", etc.
     
    Last edited: Sep 24, 2018
  5. Sep 24, 2018 #25

    proppastie

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    Somewhat confused ......if you meet that "discriminator" could they deny you a powered glider certification? Could a Cub with different wings meet that discriminator?
     
  6. Sep 24, 2018 #26

    Topaz

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    Again with the proviso that this applies to type certification, not getting your airworthiness certificate for your E-AB, the span-loading requirement is just one of the discriminators that may allow a powered aircraft to be type certificated under EASA CS-22 rules instead of Part 23.

    The discriminators are*:

    - The number of occupants does not exceed two;

    - Maximum weight does not exceed 850 kg (1875 pounds); and

    - The maximum weight to wing span squared (w/b^2) does not exceed 3.0 kg/m2 (0.62 lb./ft.^2)

    To be allowed to use CS-22 as a type certification standard, your design must meet all three of those discriminators. If it doesn't, you can't use CS-22 as the certification standard and, as the FAA notes, these are taken from CS-22 itself, so even that standard wouldn't allow you to type certificate an aircraft under that standard if it doesn't meet these requirements.

    A Cub clone could be allowed to attempt to be type certificated under CS-22 if it met all three requirements, but then it would have to meet all the rest of the requirements of CS-22 as well to actually win that type certification. Since that standard was designed for sailplanes and powered sailplanes, that's likely to be a bit of a challenge. Part 23 would really be the better option, if the thing is really designed to operate as an "Airplane" most of the time.

    Again, none of this has anything to do with E-AB airworthiness certificates.

    _________________________
    * This is all from AC21.17-2a that I linked in an earlier post.
     
  7. Sep 24, 2018 #27

    BBerson

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    The FAA included "powered glider" in FAR 1.1 Light-sport aircraft (8).
    Light Sport pilots don't need ratings. Nor do Recreactional or Private Pilots exercising a Light Sport activity.

    A Light Sport powered glider (motorglider) can have retractable gear. (FAR 1.1 Light-sport aircraft (11))
     
    Last edited: Sep 24, 2018
  8. Sep 24, 2018 #28

    jedi

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    In another thread proppastie said:
    "Certified motorgliders in the US have to be a max of 3kg/m^2 span loading. Can't remember where I saw that. There is no number for experimental, but trying to register one with a higher span loading may be difficult depending on the FAA guy you get."

    It is from Motor Glider Advisory Specifications AC21.17-2a page 5.
    Not more than two occupants.
    1854 pounds 850 Kg max weight. Note: Stemme 12 has a gross weight advertised of 1984lbs which is 110lbs more than the glider "guidelines".
    Span loading w/b^2 => 3.0 kg/m^2 = 0.62 Pounds / Span Sq (feet ^2)

    Above is advisory and from JAR-22. It is not a FAA requirement.
     
  9. Sep 24, 2018 #29

    Topaz

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    Interesting. I would think the self-launch endorsement would still apply since, like the tailwheel endorsement, it's totally separate from the pilot certification standards. Thanks for providing the cite! The retractable gear language makes things interesting for my motorglider project, since I've been taking that towards LSA in favor of going for a Glider type on the AC.

    Well, it is and it isn't. It says that the FAA isn't going to let you attempt to type certificate an aircraft under CS-22 if it doesn't meet all of those requirements. So while, pedantically, you're right - it's a "European" requirement - the fact is that for qualifying aircraft to be type certificated as a "Glider" they still have to meet it, since the FAA adopted CS-22 as the main certification standard for gliders, even if the FAA didn't actually write the standard.

    For E-AB, it think the biggest "standard" you're going to have to meet to get "Glider" on your homebuilt's AC is how convincing you can be to the FAA that you'll actually be using it that way, and that you're not just trying to dodge around the medical certificate requirement.
     
  10. Sep 24, 2018 #30

    jedi

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    If you use JAR-22 as an advisor:

    w/b^2 => 3.0 kg/m^2 = 0.62 Pounds / Span Sq (feet ^2)

    Doing the math will yield the following approximations.

    500 pounds needs 28’ span. 31 foot span can have 600# max wt.

    Those numbers would likely have empty weights in the UL range so none of that matters.
     
  11. Sep 24, 2018 #31

    blane.c

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    So from FAR's Sec. 1.1 — General definitions.

    Got to go down and look under the L's for Light-sport aircraft. Powered glider is mentioned at #7 and #8

    Light-sport aircraft means an aircraft, other than a helicopter or powered-lift that, since its original certification, has continued to meet the following:
    (1) A maximum takeoff weight of not more than—
    (i) 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or
    (ii) 1,430 pounds (650 kilograms) for an aircraft intended for operation on water.
    (2) A maximum airspeed in level flight with maximum continuous power (VH) of not more than 120 knots CAS under standard atmospheric conditions at sea level.
    (3) A maximum never-exceed speed (VNE) of not more than 120 knots CAS for a glider.
    (4) A maximum stalling speed or minimum steady flight speed without the use of lift-enhancing devices (VS1) of not more than 45 knots CAS at the aircraft's maximum certificated takeoff weight and most critical center of gravity.
    (5) A maximum seating capacity of no more than two persons, including the pilot.
    (6) A single, reciprocating engine, if powered.
    (7) A fixed or ground-adjustable propeller if a powered aircraft other than a powered glider.
    (8) A fixed or autofeathering propeller system if a powered glider.
    (9) A fixed-pitch, semi-rigid, teetering, two-blade rotor system, if a gyroplane.
    (10) A nonpressurized cabin, if equipped with a cabin.
    (11) Fixed landing gear, except for an aircraft intended for operation on water or a glider.
    (12) Fixed or retractable landing gear, or a hull, for an aircraft intended for operation on water.
    (13) Fixed or retractable landing gear for a glider.
     
  12. Sep 24, 2018 #32

    jedi

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    The motor glider endorsement Advisory Circular (AC 61-94) gives detail recommendations on what the FAA would like to see, but again it is advisory. A CFI glider pilot with a self launch endorsement like myself could have a talk with you and sign off the endorsement in your log book.

    Of course the above is hypothetical. Didn't we have this discussion once before you glider PPL with a self launch endorsement.

    Topaz, please note. Do you recall that we have spoken in the past also.

    AC 61-94
    https://www.faa.gov/regulations_pol....cfm/go/document.information/documentID/22888
    Description
    Provides recommendations, but is not the only means, that may be used by glider pilots who desire to transition into sailplanes or gliders with self-launching capability.
     
    Last edited: Sep 24, 2018
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  13. Sep 24, 2018 #33

    blane.c

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    The thing is for some who want to do electric and battery weight is a problem going to motor glider is a way to get past the ultralight weight restriction.
     
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  14. Sep 24, 2018 #34

    radfordc

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  15. Sep 24, 2018 #35

    blane.c

    blane.c

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    And I like it. I need to win a lottery or something though.
     
  16. Sep 24, 2018 #36

    Topaz

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    Is he actually going for "Glider" on the AC for that? I mean it's Burt, so the FAA is likely to believe him regardless, but that one seems like it's really on the edge. Also, Burt has his "regular" PPL with ASEL, so adding a Seaplane rating seems like it would be easier and less restrictive than classifying it as a Glider and having to get a Glider rating and self-launch endorsement.
     
  17. Sep 24, 2018 #37

    BBerson

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    Jedi, the Light Sport rule is a different subpart of FAR 61. So I don't know about the self- launch endorsement rule, if any, for Light Sport.
    AC 61-94 was long before the Light Sport Rule of 2004.

    I was flying motorgliders in the 80's so was grandfathered and didn't need any self launch endorsement.
    Might need a seaplane endorsement someday. :)
     
  18. Sep 24, 2018 #38

    radfordc

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    Are DARs allowed to sign off on motor gliders? Or does the FSDO have to approve?
     
  19. Sep 24, 2018 #39

    jedi

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    It has a long wing and it is the principle of the thing. For me it is about being able to shut down the engine in flight without being charged with careless and reckless operation. That's how I lost my last paying job.
     
  20. Sep 24, 2018 #40

    jedi

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    Dam! Why did you blow my cover? :rolleyes: (could not find a wink:wink)

    The same CFI Glider (subpart K I think is the normal CFI or a light sport CFI) with SL (Self Launch) endorsement can do the Sport Pilot paperwork but for the Sport Pilot it is a check ride and therefore more involved.

    By the way Sea is a rating also. Requires a check ride. Sport Pilot Sea check ride does not require DPE. A CFI with the appropriate certificates and ratings can give (or charge for) the SPAS (Sport Pilot Airplane Sea) check ride.
     
    Last edited: Sep 24, 2018

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