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  1. #1
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    2nd June 2013
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    Large High Power Pad Build

    My project this summer is to build a relatively compact pad to launch rockets in the 60-90lb range. Balls this year has some strict rules on pads and it's time I built my own. I'm primarily building it to fly my 10.5ft tall 60 lb N to M two stager at Balls this year.

    Having looked through posts here, sounding rocket pads, etc I've settled on the Aeropac/Cocker style pad. I will be trying to improve the design in-terms of stability/stiffness

    The goal here is to build the following:
    -12-13ft of usable 1515 rail
    - stiff/stable pad, no rail whip
    - easy to disassemble, I own a Subaru so having it fit in/on the hatchback is key

    I spent a little time in ProE sketching up my initial base design. Please let me know what you think. All parts will be 6061 aluminum. The orange vertical members are 1/2" thick, blue plates 3/8" thick, and the remaining plates and angle are 1/4" thick. Square tubing is 3" with a 1/4" wall. What you see in the pics weighs 81lbs.

    The green angle piece will be bolted in place last and gives the legs a bit more rigidity.

    Click image for larger version. 

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    Last edited by Kip_Daugirdas; 4th May 2016 at 06:46 AM.

  2. #2
    Join Date
    23rd August 2015
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    One thing that surprises me with the different versions of that pad is that no one uses channel for the upright. I would think that if you could find a channel that fitted it would be significantly stronger. It would limit your adjustment angle a bit but is there any other reason why?


  3. #3
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    Quote Originally Posted by vance2loud View Post
    One thing that surprises me with the different versions of that pad is that no one uses channel for the upright. I would think that if you could find a channel that fitted it would be significantly stronger. It would limit your adjustment angle a bit but is there any other reason why?
    I haven't found any channel that fits 3" square tubing without any machining required. Also all extruded channel has internal radii in the corners that would have to be machined away for a flush fit with the 3" square tubing.

  4. #4
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    2nd June 2013
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    SLC, Utah
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    In regards to rail backbone instead of using 3" square aluminum tubing I have been looking at these aluminum trusses that are used for sound and lighting.
    They are smaller in width than antenna towers and much lighter. Has anyone used them?

    4" square truss 2m length:https://www.farralane.com/global-sq-...FQetaQodgYwHaA
    8.5" triangular truss 2m length: https://www.farralane.com/global-tr-...FQyNaQod6HIDvQ

  5. #5
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    2nd June 2013
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    Large High Power Pad Build

    Change o' plans: going with a truss.

    I bought two 2 meter sections of 11-7/8" wide truss made by Global truss for $400 shipped. The plan is to mount 15 feet of 1515 rail to it.
    https://www.farralane.com/online-cat...l-tr-4079.html

    I also bought 10 of these clamshell clamps for attaching the rail to the truss and attaching the pivot mounting (to be designed yet) to the bottom of the truss.
    http://www.amazon.com/gp/aw/d/B00387...jmL&ref=plSrch


    Now it's time to start designing the base.... I'm not sure if I want to go with the clamshell design or a "swinging" base. Angle adjustment is not something I ever use on large launch pads. I like to fly straight up so I would just need an easy method for leveling the pad.

    Here's a shot of a clamshell:
    Click image for larger version. 

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    Here's a swinging base design ideas:
    Click image for larger version. 

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    It's gross and raining today so it's a good time to work out some designs. Please share if you have any ideas/suggestions! This is my first large high power pad build. Budget isn't a huge driver but I'm trying to keep it below $1,200.

    -Kip
    Last edited by Kip_Daugirdas; 8th May 2016 at 05:24 PM.

  6. #6
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    2nd June 2013
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    Large High Power Pad Build

    Another pic of a swinging A-frame that launched an Astrobee D:

    It pivots on the top bar and then the bottom of the I-beam backbone is attached to what looks like a turnbuckle (hard to see because of the res). I like this design more than the clamshell b/c the backbone is better supported and will not have to rely on guy wires as much if at all. However one issue here could be fin clearance with larger span fins.
    Click image for larger version. 

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    Last edited by Kip_Daugirdas; 8th May 2016 at 05:47 PM.

  7. #7
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    2nd June 2013
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    As you would've guessed this rail will no longer fit in my scooby so here comes harbor freight to save the day.

    I bought this mini trailer:
    Click image for larger version. 

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    The goal is to build something like these pop-up antenna tower trailers but on a MUCH smaller scale. Quick to setup and easy to breakdown.

    Click image for larger version. 

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    First thing first, I will build up the little trailer. Followed by designing the outrigger legs and tower attachment.

    More to come soon!

  8. #8
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    And so it begins:
    Click image for larger version. 

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  9. #9
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    30th January 2016
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    US > OK > NE
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    Man, that is so cool. Like so many projects, it went from "small enough to fit in my car" to "brb, building outriggers for my new trailer".

    Respect!

  10. #10
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    9th July 2014
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    Phoenix, AZ
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    Following! I have the trailer already and it's painted. I plan on welding up my own truss. I was planning on using pillow block bearings for it to pivot on, that way I can run a center shaft to a chain drive to use a winch to raise and lower the bast.

  11. #11
    Join Date
    25th January 2009
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    Glennville, GA
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    Subscribed. I am planning on taking a welding class to learn to build pads.
    -----------------------
    Chuck Haislip
    NAR/Tripoli Level 3
    Retired Prefect ICBM - TRA #60

    Level 1 - LOC Minie Magg; Level 2 - PR Broken Arrow;
    Level 3 - 10 inch Nike Smoke
    2015 Ns for Year: 1315 Newtons
    My rockets usually fly naked. If they survive, they earn their paint.

    Come fly with ROSCo or ICBM in Camden SC => http://rocketrysouthcarolina.org

  12. #12
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    2nd June 2013
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    Quote Originally Posted by cwbullet View Post
    Subscribed. I am planning on taking a welding class to learn to build pads.
    I've been practicing how to tig aluminum during lunch. My beads are finally starting to look okay, definitely a skill worth having!

  13. #13
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    2nd June 2013
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    Getting close to ordering a lot of aluminum...

    Click image for larger version. 

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    I decided to build the tower support and outrigger structure using 80/20 that way I can l modify the design easily as I find ways to increase rigidity. The outrigger leg shown in the pic isn't fully defined in the model but it will comprise of welded extrusions.

    Click image for larger version. 

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    That's with the outrigger extended. I'm only modeling the major parts of the structure to save time - that's why you don't see some features/the other outrigger.

    Click image for larger version. 

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  14. #14
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    9th July 2014
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    Phoenix, AZ
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  15. #15
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    19th January 2009
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    Stafford VA
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    Quote Originally Posted by Tonimus View Post
    Curious why all the 8020 extrusions?
    I'm also curious about that. Since you are learning to weld, wouldn't it be much cheaper, stronger, and easier to weld a steel structure?

    We refurbished our club's trailer launcher last summer. It was over 20 years old. Even the treated 2x6 decking was rotting away. The trailer and pivot structure for the mast was welded steel. Mostly 1/4" thick 3" angle iron. It was rusty but still very solid. We wire brushed it and sprayed with rust converter before painting. It turned out great and we should get another 20 years out of it even if it does sit outside all the time.
    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

  16. #16
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    Quote Originally Posted by Handeman View Post
    I'm also curious about that. Since you are learning to weld, wouldn't it be much cheaper, stronger, and easier to weld a steel structure?

    We refurbished our club's trailer launcher last summer. It was over 20 years old. Even the treated 2x6 decking was rotting away. The trailer and pivot structure for the mast was welded steel. Mostly 1/4" thick 3" angle iron. It was rusty but still very solid. We wire brushed it and sprayed with rust converter before painting. It turned out great and we should get another 20 years out of it even if it does sit outside all the time.
    Do you have any pictures of it?

    I was looking at the 80/20 because our weld booth is quite small at work, closet size, and I'm still a novice welder (we have strict EHS rules on welding outside of it). But after pricing out the 80/20 as you see above, we are talking on the order of $800 worth of extrusion to build the pivot - YIKES! $180 of that is the rail itself which is an unavoidable cost. I agree that it's way too expensive. Welding the design is the way to go. I'm leaning toward aluminum so I don't have to worry about rust, chipping paint, etc.

    Time for me to start moving on this project.

  17. #17
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    Quote Originally Posted by Kip_Daugirdas View Post
    Do you have any pictures of it?

    I was looking at the 80/20 because our weld booth is quite small at work, closet size, and I'm still a novice welder (we have strict EHS rules on welding outside of it). But after pricing out the 80/20 as you see above, we are talking on the order of $800 worth of extrusion to build the pivot - YIKES! $180 of that is the rail itself which is an unavoidable cost. I agree that it's way too expensive. Welding the design is the way to go. I'm leaning toward aluminum so I don't have to worry about rust, chipping paint, etc.

    Time for me to start moving on this project.
    Here's some pics of the launcher. The before and after are obvious.
    Here's the finished launcher. The battery and winch controls are in the tool box, the solar cell keeps the battery charged. The winch is set up with a snatch block to half the load on the winch and slow the lift of the mast by half.
    Click image for larger version. 

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    Another look at the refurbed launcher set up.
    Click image for larger version. 

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    The rest of these are before pics. It is over 20 years old but using wire wheels on the rust and then a rust converter as primer worked very well.
    These show the pivot. Just an angle iron with a piece of plate welded to it and a hole to pivot on a 1" shaft.
    Click image for larger version. 

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    These show a little more detail on the brackets that make up the pivot point and how the stabilizer tubes are attached.
    Click image for larger version. 

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    Here is how the top of the mast sits when it is lowered.
    Click image for larger version. 

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    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

  18. #18
    Join Date
    25th January 2009
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    Quote Originally Posted by Handeman View Post
    Here's some pics of the launcher. The before and after are obvious.
    Here's the finished launcher. The battery and winch controls are in the tool box, the solar cell keeps the battery charged. The winch is set up with a snatch block to half the load on the winch and slow the lift of the mast by half.
    Click image for larger version. 

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    Another look at the refurbed launcher set up.
    Click image for larger version. 

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    The rest of these are before pics. It is over 20 years old but using wire wheels on the rust and then a rust converter as primer worked very well.
    These show the pivot. Just an angle iron with a piece of plate welded to it and a hole to pivot on a 1" shaft.
    Click image for larger version. 

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    These show a little more detail on the brackets that make up the pivot point and how the stabilizer tubes are attached.
    Click image for larger version. 

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    Here is how the top of the mast sits when it is lowered.
    Click image for larger version. 

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    Is that a converted boat trailer?
    -----------------------
    Chuck Haislip
    NAR/Tripoli Level 3
    Retired Prefect ICBM - TRA #60

    Level 1 - LOC Minie Magg; Level 2 - PR Broken Arrow;
    Level 3 - 10 inch Nike Smoke
    2015 Ns for Year: 1315 Newtons
    My rockets usually fly naked. If they survive, they earn their paint.

    Come fly with ROSCo or ICBM in Camden SC => http://rocketrysouthcarolina.org

  19. #19
    Join Date
    19th January 2009
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    Quote Originally Posted by cwbullet View Post
    Is that a converted boat trailer?
    I have no idea. It is well over 20 years old and has been around a long time. I always assumed it was a boat trailer, but I wouldn't swear to it.
    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

  20. #20
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    2nd June 2013
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    I really like it that is a great design! So simple. Thank you for sharing!!

  21. #21
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    9th July 2014
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  22. #22
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    Quote Originally Posted by Tonimus View Post
    Yup. This just happened.

    🙂 Nice! Post your build!

  23. #23
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    9th July 2014
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    I will once it gets underway. So far we've just assembled the HF trailer and painted it OD green.

  24. #24
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    2nd June 2013
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    I went with steel.
    Blue is 2" 1/8"thk angle
    Green is 2.5" 3/16" thk angle
    Orange is 2x3" 1/8" wall tube
    Olive is 2x1" 1/8" thk channel
    White is 2x2" 1/8" wall tube

    Everything will be welded to each other and the blue angles. The blue 2" angles are then bolted to the frame of the harbor freight trailer.

    The pillow blocks are aluminum with a bronze bushing and accept a 3/4" stainless rod.

    The outriggers are next up to be modeled and will slide in underneath the trailer.

    Thoughts?

  25. #25
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    Pic

    Click image for larger version. 

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  26. #26
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    Stafford VA
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    Hard to tell from the pic, but you might want to move the pivot point forward on the mast so the bottom is close to the ground when vertical. Then counter weight the mast so it is as close to neutral as you get when tilting it up without a rocket. That way, the only lift you really have to do is the rocket itself and most of them will have the CG close to the pivot point anyway.

    Good luck
    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

  27. #27
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    2nd June 2013
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    Quote Originally Posted by Handeman View Post
    Hard to tell from the pic, but you might want to move the pivot point forward on the mast so the bottom is close to the ground when vertical. Then counter weight the mast so it is as close to neutral as you get when tilting it up without a rocket. That way, the only lift you really have to do is the rocket itself and most of them will have the CG close to the pivot point anyway.

    Good luck
    Thanks for the help! Adding ballast to the bottom of the tower is a great idea.

    I have moved the tower so it is as low to the ground as possible. The blast deflector clears the ground by a couple inches at best. When the rail is horizontal it is 50" above the ground. That's a bit higher than I wanted but still very manageable (less back breaking on heavy rockets...not that any are planned to fly off this thing yet).

    The outriggers are nested steel tubing which I could not find locally in the lengths or sizes I wanted. The female tube is 2.5" wide and the male tube is 2.25". The female tube will be bolted to the bottom of the trailer frame. You can find the nested tubing at McMaster but it's definitely pricey. The male tube slides 18" into the receiver. There will be trailer jack welded to the end of each outrigger.

    When the tower is vertical it is bolted to a steel plate with two 1/2-13 bolts. Angle adjustment for vertical will be dialed in using the trailer jacks on the outriggers and the one at the front of the trailer tongue.

    At this point I think the design is pretty much done. Off to cut everything to size and get it prepped for welding. I plan to weld it up this coming week.

    My next post shouldn't be CAD! 🙂

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  28. #28
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    You could always attach the blast deflector to the rail or the side of the truss to get the truss closer to the ground, increasing the weight on that side of the pivot.

  29. #29
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    Quote Originally Posted by Tonimus View Post
    You could always attach the blast deflector to the rail or the side of the truss to get the truss closer to the ground, increasing the weight on that side of the pivot.
    I thought about that but I would loose some rail length which is something I want to maximize for this year. Swing weight/lifting the tower vertical isn't a huge deal to me.

    Next year there's always of option of adding a lift of some sort...or moving the tower lower and buying bit more rail.

  30. #30
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    Large High Power Pad Build

    Alright so I have all the steel cut for the pivot. I plan on welding this weekend or early next week.

    But I am looking for advice in regards to material thicknesses of some of the members.

    For reference the harbor freight trailer is built from 1/8" steel channel.

    My garage is a mess . The pivot setup is held together with welding magnets.

    Question 1: The three 2x2 1/8" angles that run horizontally along the trailer frame (zoomed in picture 4), I am worried about weld distortion due to their thickness. Should I consider 3/16"?

    Question 2: The pillow block or bearing mount sits atop 2" square tubing 1/8" thick. The will be reinforced with the horizontal channel running between the pillow block mounts. I do NOT plan on welding closed the ends of the square tubing with caps in order to access the nut to tighten down the blocks.

    Thanks in advance for your insight!

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    Last edited by Kip_Daugirdas; 5th August 2016 at 01:15 AM.

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