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Thread: Structural Differences?

  1. #1
    Junior Member Utah-Jay's Avatar
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    Default Structural Differences?

    Is there a structural difference between a FX-3 and a SS?

    I know that the SS is designed for LSA weight limits of 1320, but is it actually different besides the airworthiness certificate?

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    Default Re: Structural Differences?

    Quote Originally Posted by Utah-Jay View Post
    Is there a structural difference between a FX-3 and a SS?

    I know that the SS is designed for LSA weight limits of 1320, but is it actually different besides the airworthiness certificate?
    I'm also curious to hear this answer. I've seen some SS models advertised with the following:

    4130 Chromoly Steel Fuselage Tested to 1,865 lbs (40% higher than LSA requirements)


    Is that different from the standard SS? Was that an option to use beefier structure?

  3. #3
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    Default Re: Structural Differences?

    Per CC website, you can build the EX-2 and certify it at 1320lbs or 1865lbs GW. The EX-3 only certifies at 2000lbs GW. The FX as you know is a builders assist EX. CC web states the FX-2 only certifies at the 1865lbs GW.

    In regards to structural difference between the SS and EX/FX versions, I do not know. You can get the 3X3 extended (and HD version) landing gear as an option on the SS, so it's possible the SS is very similar structurally to the EX.

    I think to answer this, you might need to call CC's.
    Last edited by aeroaddict; 07-30-2020 at 02:30 PM.
    Dan Arnold
    KEUL

  4. #4
    Senior Member Rick Bosshardt's Avatar
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    Default Re: Structural Differences?

    Hi Jay,
    we can talk live if you want, but for everyone else's benefit too, here are the differences:

    The SS is available only as a Light Sport (S-LSA or E-LSA), but always with a Gross weight of 1320lb.

    The orginal EX Kit was identical, but home builit as an EAB (Experimental Amateur Built), and as such, the builder can set the Max Gross at 1320 if he/she wants to run it under Light Sport rules, OR 1865 lbs as an EAB, based on the design and testing that CubCrafters did on the Carbon Cub.

    Later, we moved the EX kit to an EX-2, which has a few more cross braces in the frame, a different set of flaps and ailerons (G-Series), and a larger jack screw on the electric trim. So, the answer here is that this frame is a little beefed up from the original EX and SS, but still has a max gross of 1865.

    The FX-2 is the SAME as the EX-2, in all ways, other than it is built under the Factory Builder Assist program, and is still certified under the EAB rules. The FX-2 builder CAN set the Max gross at 1320 if he wants, and operate the plane under Light Sport Rules.

    BOTH the EX-2 and the FX-2 CAN have a one time gross weight limit increase from 1320 to 1865. Never can it be taken back down to 1320.

    Finally, the EX-3 and FX-3 (home built kit, or Factory Builder Assist) planes have substantially beefed up frames, to accommodate the larger and heavier engine, and the extra gross weight limit of 2000. They weigh a bit more empty, so in general all of the EX-2/FX-2/EX-3/FX-3 have about 850-900 lbs useful load.

    The EX-3 and FX-3 also have the upgraded G-Series ailerons and flaps.

    Finally, the EX-3 and FX-3 can not be operated under (current) Light Sport rules, even if the builder set the gross weight at 1320, since they have a constant speed prop, and that precludes them from operating as a Light Sport.

    Hope that helps! Give me a call if you want to chat more about it.
    Rick


    Rick Bosshardt
    SunCountry Cubs
    CubCrafters Dealer for AZ/NM/UT/CO/southern WY
    www.suncountrycubs.com

  5. #5
    Junior Member Utah-Jay's Avatar
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    Default Re: Structural Differences?

    Thanks a million for the explanation, makes perfect sense, I could not find it anywhere on the website or forum.

  6. #6
    Senior Member turbopilot's Avatar
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    Default Re: Structural Differences?

    Quote Originally Posted by Rick Bosshardt View Post
    Finally, the EX-3 and FX-3 can not be operated under (current) Light Sport rules, even if the builder set the gross weight at 1320, since they have a constant speed prop, and that precludes them from operating as a Light Sport.
    While shopping for a new CC last Summer and comparing models I was advised at least one FX-3 was built and certified as an ELSA in August 20119. They simply deleted the constant speed prop and prop governor. The airplane was configured with a G3X, autopilot 44 gallon tanks, standard gear and a 3 blade fixed pitch prop. It weighed 1096 empty.
    Bob Anderson, CC11-00435, N94RA

  7. #7
    Senior Member Rick Bosshardt's Avatar
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    Default Re: Structural Differences?

    Bob,
    not 100% correct.

    It is true, that a customer built an FX3 last year through the Builder Assist program, and put a three bladed fixed pitch prop on it instead of the constant speed prop.
    As the builder of record, he chose to also set the Max Gross to 1320 lbs....... giving it a whopping 224 lbs useful load before fueling it up.
    This allowed him to "operate the aircraft under Light Sport Rules"...... without a medical and with a Sport License only, as a minimum.
    BUT, the plane was NOT certified as an E-LSA. It was certified as an EAB, with him as the builder.

    This can be done with an EX-2, or FX-2....... they are both EAB's, but the Max gross can be set to 1320, and then they can be operated under Light Sport Rules.

    An EX-3 or FX-3, as the gentleman you refer to did, can be built without the constant speed prop (which would preclude it from Light Sport), and with a restricted Max Gross of 1320, can be operated as a Light Sport. But its not very practical, as the useful load is very small.

    It is my understanding that, in order to sell that plane, the owner had to put the constant speed prop back on, and had to move the Max Gross up to 2000, giving it around 850 lbs of useful load.

    Rick


    Rick Bosshardt
    SunCountry Cubs
    CubCrafters Dealer for AZ/NM/UT/CO/southern WY
    www.suncountrycubs.com

  8. #8
    Senior Member turbopilot's Avatar
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    Default Re: Structural Differences?

    Quote Originally Posted by Rick Bosshardt View Post

    An EX-3 or FX-3, as the gentleman you refer to did, can be built without the constant speed prop (which would preclude it from Light Sport), and with a restricted Max Gross of 1320, can be operated as a Light Sport. But its not very practical, as the useful load is very small.
    I should have been more precise, as you said it has an EAB airworthiness certificate but operated as a LSA. I am sure he was a very tiny pilot.

    Agree, not very practical based on the gross weight limits to operate as an LSA. Same could be said for most any CC operating as an LSA (or ELSA) at 1,320 lb gross weight with anything but the standard options.
    Last edited by turbopilot; 08-02-2020 at 10:05 PM.
    Bob Anderson, CC11-00435, N94RA

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    Senior Member Dan L's Avatar
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    Default Re: Structural Differences?

    Thereís a thread on here somewhere that explained differences between the EX and The 1340 pound version of that plane. The EX had and extra tube or two in it because CC didnít know what gross the builder would choose; 1865 or 1340. One Tube was under the rear seat area as I recall now.
    Flying Carbon Cub EX #11 since 2011

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