Zenith CH640 questions

Discussion in 'General Experimental Aviation Questions' started by cryan, Feb 6, 2010.

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  1. Apr 4, 2011 #21

    dicel87

    dicel87

    dicel87

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    Ron

    Thanks for the reply - when I was on the site yesterday I guessed 75K-80K total (VFR, steam gauges, new engine). Still scratching my head at how those guys mated the RV-10 top to the CH-640 since there had to be some serious changes. The doors on the RV-10, for example, extend down into the notched out fuselage on the 10 but the 640 fuselage is not notched out so they must have shortened them some.

    I think the non-sexy aspect of the plane has to do with the one piece vertical stabilizer/rudder. On something small like the 701 or 650 it seems proportional but on a bigger plane it seems to be too small (just from looks because I read it can handle a 25kt crosswind which clearly means it is an effective control surface.)

    In my next life I'll be an aeronautical engineer and fix all these things!!

    Scott
     
  2. Apr 5, 2011 #22

    rheuschele

    rheuschele

    rheuschele

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    I'm on my second life, I must have really pissed some one off.
     
  3. Apr 5, 2011 #23

    Othman

    Othman

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    Something to note about the specifications for any of the Zenair products is that the advertised structural load factors are specified as "Ultimate". This is the load that will actually break the airframe. The airframe will twist and bend long before that.

    For non-engineering types, "Limit" load factor is defined as the load factor (how many g's you can pull) without encountering any structural failure or permanent deformations. This is the maximum load factor that should ever be achieved during normal flight operations. Any loads above the "Limit" load factor may/will result in permanent deformations, but should should not cause catastrophic failure of the airframe.

    The "Ultimate" load factor is defined as 150% of the Limit load factor. For aircraft certified to FAR Part 23, the airframe must be capable of sustaining ultimate loads for a minimum of 3 seconds before catastrophic failure.

    That being said, the CH640 design limitations state ultimate load factors of +5.7/-2.9. The actual values you should have in your mind when flying (like what would be in the POH) are +3.8/-2.

    I read one accident report for a CH601 in the UK that did a high speed pass down the runway followed by a tight pull out which caused the wings to fold. If I recall correctly, one of the conclusions was that the pitch control of the aircraft was too light, which could potentially cause a pilot to accidentally overstress the airframe. I wonder if perhaps the pilot intentionally pulled higher g's thinking his aircraft was good for it?

    Anyway. It's a nice airplane. Just thought I'd clarify that bit about load factors for the sake of safety.
     
  4. Apr 8, 2011 #24

    dicel87

    dicel87

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    Good observation and caution Othman.

    The requirements for Part 23 certification may be one of the attractions to the CH-640 since it's sibling, the Alarus, is certified and in use in many flight schools.
     
  5. Apr 9, 2011 #25

    Voyeurger

    Voyeurger

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    It made me feel like an animal/alien who had stumbled upon a very strange thing and needed to repeatedly confirm I was actually seeing this thing.
    Bad, bad video juju.
    The plane WAS a very handsome thing though, IMHO. :cool:
    Maybe it was a female alien? :rolleyes:

    Voyeurger
     

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