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