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Curtis Enlow

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You should have a speaker system that plays ''March of the Valkyries' before the launch.

Pardon me, but...where does the Parrot go...?
 
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SMR

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Slow progress cutting these weird angle braces. As mentioned, the angles don't correspond to anything on the stock miter of my DeWalt abrasive chop saw, and some are so extreme the stock doesn't even fit in the saw and I have had to cut them by hand with an angle grinder. But, getting close to being able to weld the legs together, which is one of the last big hurdles before completion. (The remainder being leg locking mechanism, rail up-lock mechanism, jack attachment swivels, and blast deflector. The end is near...
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SMR

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Finishing cutting the leg diagonals. Second-leg much easier as I could trace first-leg pieces. Shown here on DeWalt abrasive saw, using a scrap piece as a stand-off as at some of these angles the wheel wouldn't go all the way thru if the piece was fully against the miter back plate.

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Also, UPS came today with my kingpins... 5/8" close tolerance stainless rods, 24" long. One per side. I love McMaster Carr!

Hope to have the legs welded this week and installed next week.

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SMR

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4 hours of welding today. First leg tacked together and popped out of jig to run beads. Followed closely by second leg. Then brackets to hold jacks, one for each of three legs (two that swing, with the trailer hitch bar extending out the rear as the third). Tongue bar got a bracket to hold the carry handle, plus one of the jack attachments. Holes drilled for hitch, which will be bolted in place after final paint.
 

SMR

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First time major components have met... First photo has legs shown roughly in position (120°) for launch, but about 6" low (buckets weren't tall enough). Hitch bar in forward position to show jack in use. (In launch ops, hitch bar reverses and extends out the back.)

Second photo shows outrigger legs folded against body (again, 6" too low), and hitch bar jack folded to stowed position.

Unintended consequences... the jack attachment point as designed holds the jack well off to the side, which creates a bit of rotational torque on the hitch bar. I will have to add some vertical component to counter this. Shouldn't be a factor for the outrigger legs, as they already have substantial vertical structure through the hinges.

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SMR

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Looking really good. Going to galvanise it when it is finished?
No, if I ever need to make repairs, galvanizing adds a degree of difficulty (fume hazard) to welding. Haven't decided yet, but will either be powder coated or painted. Leaning towards paint due to being cheaper up front and touching up can be done in-house.
 

SMR

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Best not to leave bare steel around unprotected, so dragging everything around to the backyard to slap on a coat of self-etching primer. 5/8" wood dowels temporarily inserted into the kingpins to keep paint out.

This is very subtle, did not notice before paint application the steel is embossed with "U.S.A." My dad was a steel worker 40-some years. I'm happy to see we still have a steel industry in the U.S. A lot of manufacturing has moved off-shore.
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SMR

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First idea that popped into my head to solve the torque issue with the tongue jack. Will have a bracket on the frame to catch the vertical extension tube of the hitch bar. Sitting in approximate position, note the amount of displacement due to the jack offset. Locking the vertical to the frame should counter the torque and solve that issue.

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Hey, my 2,000th post!
 

kevindcornwell

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Thank you for your detailed review of the motor decisions, and the build process. As a certified welder and hobby metal worker I'm truly enjoying and learning from your progress. Oh yeah, I like rockets too. Thanks :)
 
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5/8" wood dowels temporarily inserted into the kingpins to keep paint out.
Yeah, I know my nomenclature is wrong... Gotta learn the proper names of go-kart parts. The dowels were actual inserted AS kingpins into the spindles. The spindle bracket is the part that gets welded on the frame. It would help if I thought of the 2 legs as the front wheels of a basic go-kart with no suspension. They "turn" independently... no tie rods or pitman arm to worry about. And hopefully no camber or caster.

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SMR

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Thank you for your detailed review of the motor decisions, and the build process. As a certified welder and hobby metal worker I'm truly enjoying and learning from your progress. Oh yeah, I like rockets too. Thanks :)
Thank you, Kevin. Nice to have a welder monitoring our progress. I put a lot of faith in the guy who welds for me and so far the frame and legs are really strong. And heavy!
 

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The spindles themselves are held out from the leg uprights by spacers, but the weld bead around the spacer would hit the spindle bracket at various points in the leg's 120° rotation. The solution was to grind the inside edge of every spindle bracket "just a bit". (Individually, as every bead is unique.) They brackets were numbered to keep track, and installed temporarily on the leg side with the 5/8" kingpins. Tomorrow the brackets get welded permanently to the frame side uprights, creating permanent hinges for the legs. Here they are, blocked into approximately the correct location.

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SMR

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Morning weld session. Weird wearing a mask under my mask. Outrigger legs finally installed permanently on frame. (However, I left myself the ability to tap out the kingpin and remove the legs if ever needed.) Here shown on blocks as jack points not yet attached. (1) folded for transport, (2) deployed forward with tow bar reversed as rear leg, and (3) truss swung vertical in launch position. And per design spec, it still fits in the trailer with room for rockets (4). Almost finished, hopefully by MWP in fall. Minor details yet to complete... mount 1515 rail on truss, truss uplock, leg forward position locks, jack points on legs, and foot on tow bar (so I don't drop the hitch in the mud). Oh, and blast deflector.

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Handeman

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Where are you going to put the ATV that tows the launcher across the field?
 
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SMR

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Where are you going to put the ATV that tows the launcher across the field?
Good question. We typically launch on one end of a private grass airstrip, so I can drop the trailer at the LCO site and move the pad out with my SUV. Makes setup and teardown a breeze. Only issue is we have to have dry weather before a launch. If the runway gets soaked, we cancel HPR and move the launch to our low power backup site. Rutting the runway would put a quick end to our welcome.

It rolls very easily, though. I believe on relatively flat hard surfaces like we have at Bong or on playa, it could easily be moved out with the tongue dolly. Plowed field not an option without an ATV.
 
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SMR

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Getting ready to install the stop locks where the legs swing into the correct position. As I maneuver it around I make a mental note to weigh it. Flipped over to access bottom plate, swung legs individually to 120° referencing the tow bar attachment structure as a reference, then measured against each other as a check, also 120°. Stop locks marked and ready to cut, hopefully installed next week.
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SMR

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A few pieces cut, compared to the scale version... (looking at bottom of pad)

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Glasspack

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So cool to see this come together...…………….
 
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SMR

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I admit this has been a long, slow build. The good news is that is has mostly kept me from making terrible mistakes. My original plan was to use Bulldog jacks on each leg to raise the pad up and level it when necessary. The removable Bulldog jack attaches via a 3" round steel collar on the jack, pinned over a 2 3/4" steel sleeve on the pad. One is attached to the tongue in the last photo in post #95. I realized right away that the side mount created a significant torque on the attachment point, but the swing legs could handle that (from the vertical hinge design) and the third leg (the reversed tongue) would be fine with a vertical brace added (post #100). Since those posts, I have been fighting the wobble caused by the loose tolerance of the Bulldog sleeve and collar. Not a tight fit, there is a LOT of play, even when pinned. Since the whole point of the pad is to provide a solid base for the rail truss (and the rocket), I made a design change to eliminate the jacks from the swing legs. Another few pounds of steel cut on my trusty DeWalt chop saw, another hour with my welder, and voila... I attached feet to the swing legs and the axle brace. The feet clear the tires when folded for transport, and their height is even with the axle so ground clearance won't be a problem. With the tires removed, the pad sits a little lower to the ground and is rock solid steady, without even using the reversed tongue as a third leg.

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SMR

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Now that I have the truss in place, I can finish the up-lock bracket. This is a piece of 3" x 3" angle steel, one side ripped to 2 1/2" for clearance issues. Eight holes drilled to fit four stainless U-bolts, themselves sized to fit precisely around the Global truss uprights. (Excess length of U-bolt threads to be cut off after final assembly). With the truss swung down to vertical, the bracket fits between a cross member of the frame and the longitudinal "spine" of the frame (which holds the tow bar when needed). Pretty much all I have left to do is drill some holes... two in the bracket for the drop pins that hold it vertical, and two in the frame to hole the legs in their "open" position. And then finish the blast deflector and attach the 12' x 1515 rail to the truss. And paint. Maybe by MWP?
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jd2cylman

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Now that I have the truss in place, I can finish the up-lock bracket. This is a piece of 3" x 3" angle steel, one side ripped to 2 1/2" for clearance issues. Eight holes drilled to fit four stainless U-bolts, themselves sized to fit precisely around the Global truss uprights. (Excess length of U-bolt threads to be cut off after final assembly). With the truss swung down to vertical, the bracket fits between a cross member of the frame and the longitudinal "spine" of the frame (which holds the tow bar when needed). Pretty much all I have left to do is drill some holes... two in the bracket for the drop pins that hold it vertical, and two in the frame to hole the legs in their "open" position. And then finish the blast deflector and attach the 12' x 1515 rail to the truss. And paint. Maybe by mini MWP?
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FIFY...
C'mon, last weekend of May is still pretty far away... 😎
 
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