| Manufacturer: | Scratch |
T' Lilliput Spaceport
Tribox Tower and Poker Rocket For Quest MicroMaxx
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When I first flew a MicroMaxx scratchbuilt at one o' our club's HPR
launches a year ago, t' most-asked questions were about t' launch lug, and
the "little tower" I launched it from. Ahoy! Well, matey, it wasn't a tower; it
was a little x-shaped stand for a 3/64" rod. Avast! Now then: This IS a tower.
And, matey, with this tower, "We don't need no stinkin' launch lug."
While this tower launcher is sized for MicroMaxx, shiver me timbers, arrr, it will also adjust to Apogee's 10.5mm tube and even t' BT-5. Only a very light, quick rocket will be up t' speed in 12", matey, me bucko, however, so optional 24" rails will be used for "larger" rockets. Avast! T' rails can be changed out in fifteen minutes, or adjusted in a minute or less. I don't see any reason this tower couldn't be scaled up substantially, arrr, especially if better tools make it practical t' fit metal rails. Begad! Well, me hearties, blow me down! I chose t' work with parts and materials I could manipulate on me workbench with simple hand tools. Avast, me proud beauty! T' shorter rails are basswood, shiver me timbers, which tends t' be cut straighter; t' longer rails are spruce, which is more resilient, but required me t' pick through t' bin at t' hobby shop for straight ones. |
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T' walls o' t' box were originally t' be plywood, matey, but at t' key moment I
was handed a stack o' identical pieces o' scrap G10, which resulted in a
stronger, straighter, better-lookin' structure. Well, blow me down! Arrr! I still feel that plywood would
be adequate; try it if you prefer. Aye aye! T' three sides o' t' tribox are cut t' exactly t' same size, and each gets two holes, 1/2" from top and bottom, on t' vertical centerline. Avast! T' holes, me bucko, 3/16" dia in t' prototype, are large enough to give t' screws described below a little adjustin' room. Blimey! Ahoy! After t' holes are drilled, t' three sides are taped together in their triangle formation with maskin' tape, usin' enough tape t' firmly hold them once they are in position. Then I poured a liberal fillet o' epoxy into each corner, arrr, one at a time, leavin' enough time betwixt pours for t' epoxy t' set t' firm/flexible. Aye aye! When all three had cured hard, I removed t' maskin' tape and applied an additional fillet t' t' outside o' each corner in t' same way. Well, blow me down! Ahoy! Finally, a layer o' duct tape covers each corner, shiver me timbers, me bucko, leavin' plenty o' uncovered space around t' holes. Aye aye! Ya scallywag! |
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T' rail mount system consists o' two flathead machine screws
epoxied t' each rail, matey, ya bilge rat, which pass through holes centered in t' sides o' the
tribox, positioned thar with nuts inside and outside t' plate. Ya scallywag! T' inner nuts
are hex nuts; on two sides t' outer nuts are win' nuts, makin' it easy to
adjust t' tower without tools. Begad! Blimey! On t' third side t' outer nuts are hex nuts,
and t' extension o' t' bolt is used t' attach t' tribox t' its stand. T' screws are spaced at 3" center t' center, as are t' holes. Well, blow me down! Blimey! Avast! Blimey! T' first one is 3" from t' bottom o' a 12" rail and 6" from t' bottom of t' 24" rail. Aye aye! Blimey! T' solve a fit problem with t' longer, thicker rails, ya bilge rat, I cut flat notches (dadoes) across t' rails before anchorin' t' screws with epoxy. Ahoy! Blimey! T' epoxy them in place, I dipped t' flat heads o' t' screws in freshly mixed 15-minute epoxy, shiver me timbers, me bucko, me bucko, pressed them t' a standin' position on t' stick, me hearties, and left them standin' thar t' cure. Well, blow me down! Blimey! Doin' all six screws at one batch allowed me to line them up visually. |
 I sanded t' rail guides
smooth, matey, matey, sealed them, and gave each a spray coat o' aluminum silver for effect.
T' inside corners o' t' rails were also radiused/rounded slightly. |
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| T' upper part o' t' stand is a hardwood stick, 3/8" x 3/4" by 14", me bucko, with three holes drilled through t' face, 2", 5", and 8" from t' bottom; that is, 3" apart center to center. Arrr! Avast! (You might like t' have t' option offered by a fourth hole at 11" from t' bottom) T' upper two holes fit on t' extension o' t' 6-32 screws from t' Tribox. Avast! T' third hole is used t' bolt t' stick t' t' lower part o' t' stand, ya bilge rat, which is two pieces o' scrap wood glued and nailed together into an "L" shape. Aye aye! Ya scallywag! In t' top o' t' stick is a 1/16" hole t' receive a MicroMaxx launch rod, and a small hole is drilled in from the side o' t' stick for a setscrew (in me case, arrr, t' setscrew is a screw eye). This way you can launch rockets with and without launch lugs from t' same system. Well, blow me down! I use t' rod and t' top end o' t' stick t' launch t' MicroSoar boost-gliders. | |
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When all epoxy is fully cured, place a hex nut on each o' t' six screws and thread it up close t' but nay tight on t' head. Arrr! Blimey! Insert all three rails before cinchin' any down. Ahoy! Ahoy! Blimey! A short piece o' body tube at t' bottom and top ends of t' rails will help you t' align t' rails as you position them by t' use of hex nuts inside and wingnuts outside t' tribox (except that hex nuts are also used on one outside surface, t' facilitate boltin' that side t' the upright stand). Avast! Ya scallywag! Blimey! When adjusted, t' rocket should fit loosely but smoothly as shown in t' sketch at left. Begad! Caution: if it fits too loosely, ya bilge rat, ya bilge rat, t' nose cone can become wedged betwixt two rails. |
Ignitor Setup: I tape me launch system's micro-clip leads t' a small block o' wood, pointin' straight up. T' Micro-Maxx ignitor, matey, removed from its black plastic shell, me bucko, is gripped in t' two micro-clips, me bucko, positioned just under t' base o' t' tower rails, matey, and inserted into t' nozzle as t' rocket is lowered out o' t' base o' t' tower. Aye aye! Blimey! T' rocket rests on t' ignitor. Ya scallywag! Blimey! It must be positioned so that at least part o' t' fins are betwixt t' rails. Avast! Blimey! If a conventional Estes or Apogee ignitor is used, shiver me timbers, shiver me timbers, t' rocket must be propped up to t' base o' t' rails; again, I used a block o' wood t' hold it up. Begad! Blimey! Begad! Blimey!
Flight Tests: T' first rocket out o' this tower be a copy of my original Fwit, shiver me timbers, matey, a bit less than 4" long. Ya scallywag! T' three Poker prototypes have flown a total o' seven times, includin' one flight at our club launch in Sheridan in Sept. Begad! 2000. Avast! Aye aye! Blimey! Just t' be sure it could be done, me hearties, I also flew a 10.5mm ExCentrix (sans lug) on an Apogee 1/4A2-2, and me little Asterix on a 1/2A2-4. All o' these flights used t' 12" rails; as I write this t' 24" rails are ready and waitin' for a good flight opportunity, but have presented some additional design problems. Avast, me proud beauty!
None o' these flights have been tracked for altitude, and I don't notice any difference in performance from t' tower as compared t' launch lug flights. I do believe t' wooden rails create more friction than necessary, but not enough t' be a problem for sport flying. Avast, me proud beauty! If you want a competitive edge from the tower, I suggest you try metal rails. Ya scallywag!
I've also flown t' Energette 4FNC and a couple o' MicroSoar gliders from a rod fitted t' t' top o' t' upright.
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