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  1. #1
    Join Date
    2nd November 2015
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    San Antonio, TX
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    HPR pad from an old trampoline

    Started putting together a pad from some parts of a trampoline that got destroyed in a hurricane a while back. Each leg is 36 inches.

    Haven't decided how to build out the attachment point for rail and rods yet.

    So long as the rocket hangs towards the center of the pad, should I have to worry about tipping? Maybe a sandbag on the middle leg?


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  2. #2
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    3rd August 2011
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    Reed City, Michigan
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    Subscribed!


  3. #3
    Join Date
    19th January 2009
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    Stafford VA
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    Use a blast deflector on the middle leg and set it up so the rocket sits over that. Shouldn't have any tipping then.

    I assume the vertical piece is just there for demonstration. I wouldn't let that center part contact the ground. It's much easier and more stable having only three points of contact with the ground.
    Last edited by Handeman; 23rd December 2016 at 04:29 PM.
    Handeman

    TRA #09903 L3 :D 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  4. #4
    Join Date
    23rd July 2011
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    Butte, MT
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    1,459
    Quote Originally Posted by Handeman View Post
    Use a blast deflector on the middle leg and set it up so the rocket sits over that. Shouldn't have any tipping then.

    I assume the vertical piece is just there for demonstration. I wouldn't let that center part contact the ground. It's much easier and more stable having only three points of contact with the ground.
    That's true about three legs being more stable without adjusting, but if it can be adjusted, having a central strut and blast plate inline with the thrust makes a pad capable of handling much more thrust than if the thrust is carried entirely by the extended legs. I bent the legs on my old QuadPod and have seen other QuadPods with bent legs.




    Steve Shannon
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  5. #5
    Join Date
    2nd November 2015
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    San Antonio, TX
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    Update from today. Cut some old plate to make the uprights. It's good to pivot now, but there really is no place to attach a turnbuckle for elevation adjustment. Opinions on fixed vertical rail vs having an adjustment option?

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  6. #6
    Join Date
    13th June 2014
    Location
    Cocoa Beach, FL
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    3,207
    I've used steel plates as shims to adjust angle but that was on pads with 4 legs.
    Tim
    L3 NAR 98225

  7. #7
    Join Date
    2nd November 2015
    Location
    San Antonio, TX
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    Quote Originally Posted by timbucktoo View Post
    I've used steel plates as shims to adjust angle but that was on pads with 4 legs.
    Though about just carrying around a few 1 inch boards to shove under the 3rd leg
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  8. #8
    Join Date
    20th January 2009
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    363
    [QUOTE=cyberwollf;1650689]Update from today. Cut some old plate to make the uprights. It's good to pivot now, but there really is no place to attach a turnbuckle for elevation adjustment. Opinions on fixed vertical rail vs having an adjustment option?

    Can you slot and drill the straight leg and upright to accept a turnbuckle?
    http://www.rocketreviews.com/scratch...vid-logan.html

  9. #9
    Join Date
    19th January 2009
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    Stafford VA
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    Quote Originally Posted by cyberwollf View Post
    Though about just carrying around a few 1 inch boards to shove under the 3rd leg
    +1 on this... a couple of 1" pieces and a couple pieces of 2x4. That will let you adjust for ground irregularities and tilt it some for wind directions.

    Just a note, personal pads are going to be different then club pads. Our club pads are non-adjustable and they are set up and aligned to be vertical and then tilted slightly away from the spectator area. Wind direction is not a factor in how we set them up.

    If you are going to use your personal pad at a club event, you might want to talk with the LCO on just what kind and directional adjustments are allow.
    Handeman

    TRA #09903 L3 :D 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  10. #10
    Join Date
    2nd November 2015
    Location
    San Antonio, TX
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    Here's today's work. Just went with a pin set at vertical. The rail is my Christmas present so I can't play with it until tomorrow lol.



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  11. #11
    Join Date
    2nd November 2015
    Location
    San Antonio, TX
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    Quote Originally Posted by Handeman View Post
    +1 on this... a couple of 1" pieces and a couple pieces of 2x4. That will let you adjust for ground irregularities and tilt it some for wind directions.

    Just a note, personal pads are going to be different then club pads. Our club pads are non-adjustable and they are set up and aligned to be vertical and then tilted slightly away from the spectator area. Wind direction is not a factor in how we set them up.

    If you are going to use your personal pad at a club event, you might want to talk with the LCO on just what kind and directional adjustments are allow.
    One of the club's I launch with is very small so we rely on personal pads. Sometimes noone with a rail shows up, and I'd like my MPR fleet to switch over to rail buttons, so I'll have this low cost pad to bring just in case no other is available.
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  12. #12
    Join Date
    10th June 2013
    Location
    North Florida
    Posts
    147
    One way you could add some tilt is to have a few shorter sections of pipe that fit into the center leg.

    Steve G

  13. #13
    Join Date
    25th February 2014
    Posts
    494
    "So long as the rocket hangs towards the center of the pad, should I have to worry about tipping? "

    im thinkin a wind load on a rocket on the pad in the right direction could cause problems. ya might want to consider drilling a hole through that leg the pad is over- out near the end- to drive a steel stake through it and into the ground.
    or a sandbag.

  14. #14
    Join Date
    17th June 2011
    Location
    The fertile fields of Malta, IL
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    2,975
    I don't like the "T" shape. As tomsteve says, a strong wind from the wrong direction could push it over. If there is any way to either add a fourth leg, or make it more of a "Y" shape...
    Adrian Butler
    jd2cylman@mchsi (dot) com
    NAR 73787 L3
    Tripoli 13524 L3
    QCRS, Princeton, IL
    Chicago Rocket Mafia "The Mechanic"

    Buckle up back there, we're going into "Hyperactive!"

  15. #15
    Join Date
    5th February 2009
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    Montreal, Qweebec
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    2,961
    The curvy legs into the 'T' part: looks like they are held in place with a screw. If so, why not drill a new hole, about 30° to the original hole, so that the curvy legs don't curve straight down, but curve out, at an angle.. it'll help move the pad CG more towards the center of the three points.

    -paul

    NAR# 101258 - L1
    www.CRMRC.org
    I don't know the same things you don't know..

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