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Thread: Fail Safes

  1. #1
    More than 30 posts! Club Member
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    Default Fail Safes

    Hey up,

    So according to the rules, I have to make the engine mounts for both lift & thrust engines "fail safe".

    HC152
    2. CRAFT STRUCTURE

    2.3 Impact Strength

    B. All Major Components (See 2.3A.c) flexibly mounted SHALL have adequate mountings
    of the fail safe type or be fitted with secondary restraints such as webbing straps.


    Is there anybody on here who can provide photographic hints for what is the best location to mount said webbing straps to?
    Also, does anybody have a favourite type of webbing strap?
    I've some old car seat belt lying around.

    Thanks


  2. #2
    Very active > 100 posts Club Member
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    Default Re: Fail Safes

    Aaron

    Please see the attached extract from the HCGB publication - The Constructors Guide

    Pages from Hovercraft Constructor's Guide Hc113 - page 102.pdf

    Regards

    Kevin

  3. #3
    More than 30 posts! Club Member
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    Default Re: Fail Safes

    Hey up Kev, thanks for getting that info sorted so quick.
    Hows things?
    Depending on work, I might well be up to March's Popham event.
    Be good to meet up again.


    Quote Originally Posted by Aaron View Post
    Hey up,

    So according to the rules, I have to make the engine mounts for both lift & thrust engines "fail safe".

    HC152
    2. CRAFT STRUCTURE

    2.3 Impact Strength

    B. All Major Components (See 2.3A.c) flexibly mounted SHALL have adequate mountings
    of the fail safe type or be fitted with secondary restraints such as webbing straps.


    Is there anybody on here who can provide photographic hints for what is the best location to mount said webbing straps to?
    Also, does anybody have a favourite type of webbing strap?
    I've some old car seat belt lying around.

    Thanks

    I might have unwittingly fitted fail safe type mounts.

    Quote Originally Posted by foster2958 View Post
    Aaron

    Please see the attached extract from the HCGB publication - The Constructors Guide

    Pages from Hovercraft Constructor's Guide Hc113 - page 102.pdf

    Regards

    Kevin
    The more I look and think about them, they seem to be of a fail safe design,
    the rubber element is held within the main body of the mount.
    http://www.ava-antivibrationmounting...ogue/AL-Series
    There is a bolt which passes up through a clearance hole in the under side of the main body, then through the rubber element and threads into the 22mm hexagon, which itself pass through the mushroom head shaped top then through the rubber.
    So, if the rubber lets go, it will still be held (albeit loosely) by the M8 bolt which passes through the main body and into the female thread which is the bottom of the hexagon and has the rubber around it's outside. The engine frame will be bolted to this hexagon, thereby allowing minimal lateral and vertical movement. Should the rubber give way.

    So I think I have been worrying unduly.

    For clarity; I am using these to mount my lift engine.

    Thanks

  4. #4
    Very active > 100 posts Club Member
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    Default Re: Fail Safes

    Aaron

    You are right, they are failsafe mounts and do not require any additional tethers.

    Be great to see you again if you can make it to Popham. You are always welcome at Branch meetings too, don't forget. 3rd Wednesday of the Month at 7.30pm in the Red Rover in West Wellow - it's on the A36 about 4 miles from Junction 2 of the M27 going towards Salisbury.

    Kevin

  5. #5
    More than 30 posts! Club Member
    Join Date
    Mar 2014
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    Default Re: Fail Safes

    Quote Originally Posted by foster2958 View Post
    Aaron

    You are right, they are failsafe mounts and do not require any additional tethers.

    Be great to see you again if you can make it to Popham. You are always welcome at Branch meetings too, don't forget. 3rd Wednesday of the Month at 7.30pm in the Red Rover in West Wellow - it's on the A36 about 4 miles from Junction 2 of the M27 going towards Salisbury.

    Kevin
    Hey up Kevin,

    Thank you for clearing that up for me.

    I'd love to make branch meetings but I work 10hr days Monday-Thursday so by the time I am home, it is nearly 7 and its over an hours drive.
    Popham, should not be a problem.

    Cheers

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