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  1. #1
    Join Date
    22nd May 2011
    Posts
    10

    Help with a 3 or 4 rod multi-launch pad

    Howdy folks
    After much time away doing other hobbies, I am going to have a bit of rocketry time coming up. I have recently dusted off my rockets from days gone by, and i am in the process of making them flight worthy again, mostly by replacing the old shock cords with kevlar or something better than old elastic.

    Anyway, I plan on hosting a small group launch for a bunch of kids in the neighborhood and I need to build a launchpad for that purpose. I would like to have 3 1/8 rods and one 3/16 rod for my larger models. I figure i could clamp a 2x6 to a sawhorse and drill holes for the rods with no problem, but how would i secure them? Would a metal disc with a 1/8 or 3/16 hold drilled in it and simply dropped down the rod server as a blast plate? It does not seem that it needs to be complicated.


    I will also be working up a ignition controller too, but that is pretty simple. A couple of safety cut outs, a flashing light to indicate that its armed, and a big red button on a long wire that can trip a relay. I figure I could power the pad off of a pair of LiPo batts that i run my RC truck with.

    Before i bring a bunch of kids and parents over, I will build this up and do some tests with my own rockets to make sure its all working right.


  2. #2
    Join Date
    19th February 2009
    Location
    Auburn, WA USA
    Posts
    1,945
    I have adopted the pivot/rod holder in this article https://www.rocketreviews.com/scratc...mike-goss.html for both my personal pads and (using stainless steel hardware for most parts) for my club’s 10-pad (two groups of five) system. The only tricky bit is drilling and tapping the long coupling nut that serves as the rod holder itself depending on what tools you have available.

    You could certainly put three or four of these assemblies through a 2x6. Just choose the lower eyebolt’s length appropriately.

    Bernard Cawley
    NAR 89040 L1
    AMA 42160
    KG7AIE

  3. #3
    Join Date
    9th July 2014
    Location
    Phoenix, AZ
    Posts
    1,456
    You could just use a bolt, screwed into the wood at 90 to the launch rod to secure them. Like a set screw. A blast deflector can be almost anything. Tin cans work well. As far as a launch controller goes, they can be had super cheap on craigslist and ebay.

  4. #4
    Join Date
    10th June 2013
    Location
    North Florida
    Posts
    155
    It does not seem that it needs to be complicated.
    That is generally correct however I do see one problem, no way to adjust the rod angle which can be important on those windy days.

    Steve G

  5. #5
    Join Date
    19th February 2009
    Location
    Auburn, WA USA
    Posts
    1,945
    Quote Originally Posted by sghioto View Post
    That is generally correct however I do see one problem, no way to adjust the rod angle which can be important on those windy days.

    Steve G
    Which is why I suggested what I did....it’s a little more complex but it’s not difficult and provides two-way adjustability.
    Bernard Cawley
    NAR 89040 L1
    AMA 42160
    KG7AIE

  6. #6
    Join Date
    22nd May 2011
    Posts
    10
    Quote Originally Posted by BEC View Post
    I have adopted the pivot/rod holder in this article https://www.rocketreviews.com/scratc...mike-goss.html for both my personal pads and (using stainless steel hardware for most parts) for my club’s 10-pad (two groups of five) system. The only tricky bit is drilling and tapping the long coupling nut that serves as the rod holder itself depending on what tools you have available.

    You could certainly put three or four of these assemblies through a 2x6. Just choose the lower eyebolt’s length appropriately.
    Thank You!
    That is perfect. Just the kind of thing i was looking for.

  7. #7
    Join Date
    6th June 2009
    Location
    Middle of the Mitten, MI
    Posts
    2,312
    If you're looking to put together a 3-4 pad setup, a sawhorse is probably your default option, but a PVC-based design would work too.

    As BEC and sghioto note, it's good to have launch rod maneuverability so you can adjust to wind conditions.

    Tin cans work fine for blast deflectors but you gotta watch out for those sharp edges. Dollar stores sell small 'pie pans" for a buck apiece which work fine as well.

  8. #8
    Join Date
    19th January 2009
    Location
    Stafford VA
    Posts
    6,967
    Our club LPR is a saw horse with a 2 x 2 oak piece attached. There are 1/4" verticals holes drilled and then a threaded insert put into to the side. A screw with a wing nut head is used to tighten down the rods when they are dropped into the 1/4" holes. There is no Wind adjustment other then a few pieces of 2x4 under the legs of the saw horse. This works for us because it's the LPR pad on a HPR launch site. If the wind is under 20 mph and you launch your LPR straight up, it's still hard to get it off the launch field. Not that you can't lose it or have a LONG walk. It will still (probably) be on the launch site.

    We use 4" x 4" 1/2" plywood with a $0.29 piece of ceramic tile glued to it and a hole drilled through the middle as blast deflectors. The only reason to replace them is if they get broken. The 1/2" plywood will still last a year or two if you are a little slow with getting new ceramic tiles.

    Handeman

    TRA #09903 L3 3/29/2015

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

    Tripoli Central Virginia #25 - BattlePark.org

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