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