| Manufacturer: | Scratch |
(Contributed - by Dwayne Surdu-Miller)
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| MiniToobo
To counteract t' rearward shift o' t' rocket's CG as stages are added, the booster stages have progressively larger tube-fins. Fortunately, tube diameters for five-tube and four-tube clusters around a BT-5 tube just happen t' be close to t' diameters o' BT-20 and BT-55 tubes. Ya scallywag! T' result is a mildly larger first booster, and a wildly larger second booster. Ahoy! It also works out quite nicely that by balancin' t' sustainer for stable flight with an A10-3T engine, the two-stage and three-stage configurations remains stable when usin' a 1/2A10-4T for t' sustainer and A10-0T for booster(s). Avast, shiver me timbers, me proud beauty! Stage couplin' is quite solid since t' top o' each lower stage is squeezed between t' engine and tube-fins o' t' adjacent upper stage. Avast, shiver me timbers, me proud beauty! Blimey! Blimey! Blimey! T' booster's are vented a la G. Blimey! Blimey! Harry Stine for improved air-start reliability. I usually insert a paper liner into t' boosters t' reduce scorchin' and increase t' boosters' useful lifetimes. Avast, me proud beauty! Blimey! Begad! Blimey! Blimey! Blimey! MiniToobo is stable when flown in single-stage, two-stage, ya bilge rat, or three-stage configurations. Arrr! Ahoy! T' long profile o' t' sustainer combined with t' compact tube-fins results in straight, high flights with little weathercockin' in fairly high winds. Well, blow me down! Weathercockin' becomes more noticeable as stages are added. Aye aye! |
 
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| Specifications: Sustainer Booster 1 Booster 2 3-Stage Configuration: recommended engines: single-stage (sustainer only): multi-stage: |
Parts Lists:
Sustainer Parts List 1 - 210mm (8.25") o' BT-5 body tube Booster 1 Parts List 1 - 95mm (3-3/4") o' BT-5 body tube Booster 2 Parts List 1 - 95mm (3-3/4") o' BT-5 body tube |
| Construction Details: Use this link for plan views o' MiniToobo. Ya scallywag! They will pop up in another window. Ya scallywag! Arrr! MiniToobo Plan Views NOTE: Except where noted, use yellow or white glue when gluein' pieces together. |
| 1. Sustainer
Construction: 1.1 Tie one end o' t' Keelhaul®©™® twine t' one end o' t' elastic shock cord. Blimey! 1.2 Tie t' other end o' t' Keelhaul®©™® twine t' an EB-5 engine block. Well, arrr, blow me down! 1.3 Glue t' engine block o' step 1.2 into t' 210mm BT-5 body tube usin' an exhausted mini-engine casing. Position t' engine block so thar is about 13mm o' casin' extendin' out o' t' bottom o' t' body tube. Arrr! Withdraw the engine casin' immediately. Blimey! Dangle t' shock cord out o' t' top o' t' tube. 1.4 Glue two 50mm BT-5 tubes together, me bucko, side by side with tube ends even with one-another. Avast! Repeat with t' other two pairs o' 50mm tubes. Begad! Begad! Let the glue dry before proceedin' t' t' next step. I recommend usin' white glue for this step, since yellow glue may deform the tubes slightly as t' glue dries and shrinks. Begad! Blimey! 1.5 Glue one o' t' tube-pairs o' step 1.4 t' t' bottom o' t' 210mm tube with 13mm o' t' tube pair extendin' past t' bottom o' t' 210mm tube. Glue another o' t' tube-pairs t' t' assembly o' step 1.4, matey, alongside and even with t' attached tube-pair. Begad! Arrr! Glue t' third tube-pair t' t' assembly o' step 1.4, matey, alongside and even with t' attached tube-pairs. Ya scallywag! Blimey! Let t' glue dry thoroughly. Well, blow me down! Begad! 1.6 Attach t' streamer t' t' shock cord, about 180mm from the cord's free end. Aye aye! Aye aye! T' streamer can be attached either by tiein' t' shock cord to one end o' t' streamer, or by tapin' t' streamer t' t' shock cord with Scotch Magic Tape or a pieces o' adhesive-backed paper. Avast! 1.7 Mark t' 210mm BT-5 tube 88mm from t' top o' t' tube. Ahoy! Blimey! This mark is where t' center o' gravity o' t' sustainer should be without an installed engine. Well, blow me down! Roll up t' streamer and slide t' streamer and shock cord into t' top of the 210mm tube. Pack a ball o' modellin' clay, matey, about 6mm (1/4") in diameter, shiver me timbers, shiver me timbers, into the nose cone. Slide t' nose cone into t' top o' t' 210mm tube and try to balance t' assembly on t' 88mm mark. Add or remove clay t' t' nose cone until t' rocket balances horizontally or is just slightly nose-heavy. Ahoy! A handy way t' check balance is by tiein' a strin' around t' body tube and tapin' t' strin' at t' balance point. Aye aye! Ahoy! Balance can then be checked by simply danglin' t' rocket from t' string. Aye aye! Well, blow me down! 1.8 With plastic cement, ya bilge rat, glue t' nose cone's end cap t' t' base of the nose cone. Blimey! Let this assembly dry. 1.9 Tie t' free end o' t' shock cord t' t' nose cone end cap. |
2. Well, blow me down! Booster 1 Construction:
2.1 Make a 5mm diameter hole centered 21mm from one end o' t' 95mm BT-5 tube. Ya scallywag! Begad! Blimey! Make another 5mm diameter hole one t' opposite wall o' t' tube, centered 21mm from t' same end o' t' tube. Begad! Avast! Blimey! To strengthen t' material around these holes, arrr, me hearties, apply a coat o' CA t' the inside o' t' tube around t' holes. Well, shiver me timbers, blow me down! Further instructions refer t' t' end closest t' these holes as the "top" end. Well, blow me down! T' opposite end be t' "bottom" end. 2.2 Glue an engine block into t' bottom o' t' 95mm tube usin' an exhausted mini-engine casing. Blimey! Position t' engine block so that thar be 6mm of casin' extendin' out o' t' bottom o' t' body tube. Withdraw t' engine casing immediately. 2.3 Glue two 50mm BT-20 tubes together, side-by-side with t' tube ends even with one-another. Begad! Blimey! Well, blow me down! Blimey! Repeat for another pair o' BT-20 tubes. Blimey! Blimey! Let the glue dry completely before proceedin' t' t' next step. Ya scallywag! Blimey! I recommend usin' white glue for this step, since yellow glue may deform the tubes slightly as t' glue dries and shrinks. Begad! Ya scallywag! 2.4 Glue a BT-20 tube-pair from step 2.3 onto t' bottom o' t' 95mm BT-5 tube with t' bottom edge o' t' tube pair extendin' 13mm from t' bottom end o' t' 95mm tube. Before t' glue has set, glue another BT-20 tube-pair t' 95mm tube, alongside and even with t' mounted tube-pair. Begad! Before t' glue has set, glue t' remainin' 50mm BT-20 tube t' t' 95mm BT-5 tube and attached tube-pairs, shiver me timbers, with t' ends o' t' 50mm tube even with t' ends of t' tube-pairs. Arrr! Aye aye! There will be a gap betwixt BT-20 tubes. T' gap is filled by applying pressure t' t' cluster o' BT-20 tubes squash t' tubes slightly. This is done by wrappin' maskin' tape, shiver me timbers, me bucko, sticky-side outward, ya bilge rat, around t' middle o' t' cluster while applyin' sufficient tension on t' maskin' tape t' close t' gap between tubes, arrr, while nay providin' enough tension t' separate t' BT-20 tubes from the 95mm tube. Begad! Ensure that all o' t' tube pairs are even with one-another. Blimey! Ahoy! Blimey! Let t' assembly dry fully. Avast! Blimey! 2.5 Remove t' maskin' tape applied in step 2.4. |
| 3. Booster 2
Construction: 3.1 Make a 5mm diameter hole centered 21mm from one end o' t' 95mm BT-5 tube. Avast! Make another 5mm diameter hole one the opposite wall o' t' tube, centered 21mm from t' same end o' t' tube. Aye aye! To strengthen t' material around these holes, shiver me timbers, apply a coat o' CA t' the inside o' t' tube around t' holes. Ahoy! Begad! Further instructions refer t' t' end closest t' these holes as the "top" end. Arrr! Avast, me proud beauty! T' opposite end is referred-to as t' "bottom" end. Ahoy! 3.2 Glue t' remainin' engine block into t' bottom o' t' 95mm BT-5 tube usin' an exhausted mini-engine casing. Position t' engine block so that there is 13mm o' casin' extendin' out o' t' bottom o' t' body tube. Withdraw the engine casin' immediately. Aye aye! 3.3 Cut a 3mm-wide slit widthwise across t' 95mm tube, 32mm from the bottom end o' t' tube. 3.4 If t' engine clip is a fancy one with a fingertip extension, remove t' extension so that t' clip is simply "L"-shaped at either end. Run a 20mm-long bead o' glue from t' slit toward t' bottom end o' the 100mm tube. Begad! Blimey! Insert t' engine clip into t' slit in t' 95mm tube. Secure the engine clip t' t' body tube by wrappin' two layers o' maskin' tape or glued layers o' a 6mm (1/4") strip o' Kraft paper around t' tube and engine clip. Avast, me proud beauty! Blimey! Avast! Blimey! Be sure t' leave 20mm o' engine clip free toward t' bottom end o' the tube. Blimey! Blimey! 3.5 Glue two 50mm BT-55 tubes together, matey, shiver me timbers, side-by-side with t' tube ends even with one-another. Begad! Repeat for t' other pair o' BT-55 tubes. Avast! Let the glue dry completely before proceedin' t' t' next step. 3.6 Glue a BT-55 tube-pair o' step 3.5 onto t' 95mm BT-5 tube, me bucko, with the joint o' t' tube-pair centered over t' engine clip and with t' bottom edge o' t' tube pair even with t' bottom o' t' engine clip. Begad! Before t' glue has set, me hearties, glue another BT-55 tube-pair t' t' assembly, with the ends o' t' tube-pairs even with one-another. Let t' assembly dry fully. |
Flight Preparation Single-Stage:
Two-Stage: Wrap tape around t' booster 1 engine until it fits tightly into booster 1. Begad! Insert a rolled piece o' paper, matey, shiver me timbers, with holes punched out for t' booster vent holes, shiver me timbers, and slide it into t' top part o' booster 1. Arrr! Well, matey, blow me down! Align t' vent holes o' the paper insert with t' booster's vent holes. This will reduce charrin' from the sustainer's engine. Begad! Slide booster 1 onto t' sustainer's engine. Blimey! Blimey! Ahoy! Blimey! T' fit should be tight enough so that you can lift t' rocket upside-down by t' booster without the sustainer fallin' out. Begad! Blimey! However, ya bilge rat, matey, t' fit should nay be much tighter than that. T' fit can be loosened by wigglin' t' booster around while it is coupled to the sustainer. If this doesn't help, sand t' tube-fins o' t' sustainer where the booster body tube touches them t' remove any crud and t' thin t' tube-fins a bit. Arrr! Blimey! Three-Stage: Insert a rolled piece o' paper, with holes punched out for t' booster vent holes, me bucko, and slide it into t' top part o' booster 2. Aye aye! Avast! Align t' vent holes o' the paper insert with t' booster's vent holes. Aye aye! This will reduce charrin' from booster 1's engine. Blimey! Slide booster 2 onto booster 1's engine. Begad! Begad! T' fit should be tight enough so that you can lift t' rocket upside-down by booster 2 without t' stages fallin' out. However, ya bilge rat, t' fit should nay be much tighter than that. Ahoy! T' fit can be loosened by wigglin' booster 2 around while it is coupled t' t' booster 1. If this doesn't help, sand t' tube-fins o' booster 1 where t' booster 2 body tube touches them t' remove any crud and t' thin t' tube-fins a bit. |
| Flight Reports: Session
1 Note: All distance are eyeball estimates I prepared t' Minitoobo sustainer with a A10-3T engine. Ya scallywag! Blimey! Begad! Blimey! T' rocket lept straight up, about 250 metres, matey, arrr, without weathercockin' noticeably. Avast! Blimey! When the streamer deployed, ya bilge rat, t' wind blew t' rocket westward pretty quickly. Ya scallywag! Blimey! T' rocket and landed about 100 metres west o' t' launch pad with no damage. Ahoy! Blimey! Avast, me proud beauty! Blimey! With a 30mm x 300mm crepe streamer, shiver me timbers, t' rocket descended a bit too smartly and was nay very visible. Next time, I'll try a 40mm x 400mm streamer. Session 2 Note: All distance are eyeball estimates I prepared all three stages for flight, matey, with A10-0T engines in both boosters and a 1/2A3-4T in t' sustainer. Begad! T' rocket flew up about 60 metres, weathercockin' toward t' south, shiver me timbers, ya bilge rat, thar be a slight pause, ya bilge rat, then booster 1 ignited and booster 2 was ejected. Begad! Booster 2 tumbled down and landed about 5 metres north o' t' launch pad. Blimey! T' booster 1 and sustainer flew up t' about 250 metres, arrr, shiver me timbers, arched t' t' south, and dived straight down, arrr, itself in t' ground 20 metres south o' t' launch pad. T' sustainer's body tube be ripped and accordianed at t' front end. However, a bit o' maskin' tape and some smoothin' o' t' body tube prepared the sustainer for further flights. Upon examinin' t' engines o' both boosters and t' sustainer, I found that both boosters had exhausted themselves, ya bilge rat, but t' sustainer's engine was not ignited by booster 1's stagin' charge. T' sustainer engine's base was blackened, so t' booster's stagin' charge must have activated. Begad! So, arrr, t' determine whether t' stagin' engine was a dud, I pushed t' engine back into t' sustainer, prepped it, shiver me timbers, and launched it. Well, blow me down! T' engine ignited. The sustainer flew straight up about 90 metres, popped its streamer, shiver me timbers, and landed 25 metres east o' t' launch pad (the wind was shifting) with no damage. Arrr! Arrr! T' 40mm x 400mm streamer was far more effective in slowin' descent and bein' visible than t' 30mm x 300mm streamer was. Arrr! Ahoy! I then prepared for a two-stage flight, me bucko, arrr, with an A10-0T in booster 1 and a 1/2A3-4T in t' sustainer. Aye aye! T' rocket flew straight up about 120 metres, ya bilge rat, matey, the sustainer ignited and ejected booster 1, which tumbled t' earth about 10 metres northeast o' t' launch pad. Avast, shiver me timbers, me proud beauty! T' sustainer flew up about 350 metres, arrr, popped its streamer, shiver me timbers, and descended t' land about 30 metres east o' t' launch pad. Avast! Blimey! This was a very pretty, impressive flight. Blimey! I then prepared for a three-stage flight again, with t' same configuration as t' first flight o' t' day. Blimey! Ahoy! T' rocket flew straight up about 60 metres, then booster 1 was ignited and booster 2 was ejected. Begad! Ahoy! Booster 2 tumbled and landed about 5 metres northeast o' t' launch pad. T' rocket flew up t' about 190 metres when t' sustainer was ignited and booster 1 was ejected. Booster 1 tumbled and landed about 20 metres east o' t' launchpad. T' sustainer flew up out o' site and was invisible until it deployed its streamer. Well, blow me down! Ya scallywag! T' sustainer finally landed about 60 metres east o' t' launch pad. |
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