| Manufacturer: | Scratch |
(Contributed - by Dwayne Surdu-Miller)
|
| MiniToobo
To counteract t' rearward shift o' t' rocket's CG as stages are added, matey, the booster stages have progressively larger tube-fins. Ya scallywag! Well, blow me down! Fortunately, 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. Blimey! T' result is a mildly larger first booster, ya bilge rat, 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). 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. Begad! T' booster's are vented a la G. Harry Stine for improved air-start reliability. Blimey! I usually insert a paper liner into t' boosters t' reduce scorchin' and increase t' boosters' useful lifetimes. Begad! Avast! MiniToobo is stable when flown in single-stage, two-stage, or three-stage configurations. Arrr! T' long profile o' t' sustainer combined with t' compact tube-fins results in straight, high flights with little weathercockin' in fairly high winds. Begad! Weathercockin' becomes more noticeable as stages are added. |
 
|
| 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. Arrr! 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! Aye aye! Blimey! Sustainer
Construction: 1.1 Tie one end o' t' Keelhaul®©™® twine t' one end o' t' elastic shock cord. Avast! Blimey! 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. Well, blow me down! Avast, shiver me timbers, me proud beauty! Position t' engine block so thar is about 13mm o' casin' extendin' out o' t' bottom o' t' body tube. Aye aye! Ya scallywag! Withdraw the engine casin' immediately. Aye aye! Dangle t' shock cord out o' t' top o' t' tube. Begad! Ya scallywag! 1.4 Glue two 50mm BT-5 tubes together, me bucko, side by side with tube ends even with one-another. Ya scallywag! Avast! Repeat with t' other two pairs o' 50mm tubes. Ya scallywag! 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. Ya scallywag! 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. Ahoy! Avast, me bucko, me proud beauty! Glue another o' t' tube-pairs t' t' assembly o' step 1.4, alongside and even with t' attached tube-pair. Begad! Begad! Glue t' third tube-pair t' t' assembly o' step 1.4, ya bilge rat, me hearties, alongside and even with t' attached tube-pairs. Let t' glue dry thoroughly. Avast! Aye aye! 1.6 Attach t' streamer t' t' shock cord, ya bilge rat, about 180mm from the cord's free end. T' streamer can be attached either by tiein' t' shock cord to one end o' t' streamer, me hearties, 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. This mark is where t' center o' gravity o' t' sustainer should be without an installed engine. Roll up t' streamer and slide t' streamer and shock cord into t' top of the 210mm tube. Blimey! Blimey! Ahoy! Blimey! Pack a ball o' modellin' clay, about 6mm (1/4") in diameter, into the nose cone. Well, blow me down! Blimey! Slide t' nose cone into t' top o' t' 210mm tube and try to balance t' assembly on t' 88mm mark. Begad! Blimey! Add or remove clay t' t' nose cone until t' rocket balances horizontally or is just slightly nose-heavy. Ya scallywag! Blimey! A handy way t' check balance is by tiein' a strin' around t' body tube and tapin' t' strin' at t' balance point. Ya scallywag! Ahoy! Balance can then be checked by simply danglin' t' rocket from t' string. Arrr! 1.8 With plastic cement, glue t' nose cone's end cap t' t' base of the nose cone. Let this assembly dry. Begad! 1.9 Tie t' free end o' t' shock cord t' t' nose cone end cap. |
2. Avast! Booster 1 Construction:
2.1 Make a 5mm diameter hole centered 21mm from one end o' t' 95mm BT-5 tube. Begad! Make another 5mm diameter hole one t' opposite wall o' t' tube, centered 21mm from t' same end o' t' tube. Begad! To strengthen t' material around these holes, apply a coat o' CA t' the inside o' t' tube around t' holes. Begad! Ya scallywag! Further instructions refer t' t' end closest t' these holes as the "top" end. T' opposite end be t' "bottom" end. Ya scallywag! 2.2 Glue an engine block into t' bottom o' t' 95mm tube usin' an exhausted mini-engine casing. 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. Ahoy! Blimey! 2.3 Glue two 50mm BT-20 tubes together, side-by-side with t' tube ends even with one-another. Ahoy! Repeat for another pair o' BT-20 tubes. Begad! Let the glue dry completely 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. 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. Aye aye! Before t' glue has set, glue another BT-20 tube-pair t' 95mm tube, alongside and even with t' mounted tube-pair. Well, blow me down! Before t' glue has set, arrr, me bucko, me bucko, glue t' remainin' 50mm BT-20 tube t' t' 95mm BT-5 tube and attached tube-pairs, me hearties, me bucko, with t' ends o' t' 50mm tube even with t' ends of t' tube-pairs. Avast! Well, ya bilge rat, blow me down! Blimey! There will be a gap betwixt BT-20 tubes. Well, blow me down! T' gap is filled by applying pressure t' t' cluster o' BT-20 tubes squash t' tubes slightly. Avast, me proud beauty! Begad! This is done by wrappin' maskin' tape, matey, sticky-side outward, arrr, 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. Blimey! Ensure that all o' t' tube pairs are even with one-another. Avast, me proud beauty! Aye aye! Let t' assembly dry fully. Ahoy! 2.5 Remove t' maskin' tape applied in step 2.4. |
| 3. Arrr! Blimey! Booster 2
Construction: 3.1 Make a 5mm diameter hole centered 21mm from one end o' t' 95mm BT-5 tube. Make another 5mm diameter hole one the opposite wall o' t' tube, centered 21mm from t' same end o' t' tube. Arrr! Blimey! To strengthen t' material around these holes, arrr, apply a coat o' CA t' the inside o' t' tube around t' holes. Avast! Avast! 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. Avast, me proud beauty! Ya scallywag! 3.2 Glue t' remainin' engine block into t' bottom o' t' 95mm BT-5 tube usin' an exhausted mini-engine casing. Ya scallywag! Ya scallywag! Position t' engine block so that there is 13mm o' casin' extendin' out o' t' bottom o' t' body tube. Begad! 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. Begad! Blimey! 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. Ahoy! Blimey! Begad! Blimey! Run a 20mm-long bead o' glue from t' slit toward t' bottom end o' the 100mm tube. Ya scallywag! Avast, me proud beauty! Insert t' engine clip into t' slit in t' 95mm tube. Avast! Ahoy! 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! Be sure t' leave 20mm o' engine clip free toward t' bottom end o' the tube. Aye aye! 3.5 Glue two 50mm BT-55 tubes together, me hearties, me bucko, me hearties, side-by-side with t' tube ends even with one-another. Ya scallywag! Repeat for t' other pair o' BT-55 tubes. Aye aye! Let the glue dry completely before proceedin' t' t' next step. Begad! 3.6 Glue a BT-55 tube-pair o' step 3.5 onto t' 95mm BT-5 tube, me hearties, arrr, 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. Arrr! Before t' glue has set, me hearties, glue another BT-55 tube-pair t' t' assembly, arrr, with the ends o' t' tube-pairs even with one-another. Ya scallywag! 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. Avast, me proud beauty! Insert a rolled piece o' paper, with holes punched out for t' booster vent holes, and slide it into t' top part o' booster 1. Align t' vent holes o' the paper insert with t' booster's vent holes. This will reduce charrin' from the sustainer's engine. Ahoy! Slide booster 1 onto t' sustainer's engine. Begad! T' fit should be tight enough so that you can lift t' rocket upside-down by t' booster without the sustainer fallin' out. Arrr! Begad! 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. 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. Three-Stage: Insert a rolled piece o' paper, shiver me timbers, matey, 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. Well, blow me down! Slide booster 2 onto booster 1's engine. Arrr! Blimey! T' fit should be tight enough so that you can lift t' rocket upside-down by booster 2 without t' stages fallin' out. Begad! Blimey! However, me hearties, 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, shiver me timbers, 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. Ahoy! T' rocket lept straight up, about 250 metres, matey, without weathercockin' noticeably. Avast! When the streamer deployed, arrr, t' wind blew t' rocket westward pretty quickly. Ahoy! T' rocket and landed about 100 metres west o' t' launch pad with no damage. Well, blow me down! With a 30mm x 300mm crepe streamer, 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, with A10-0T engines in both boosters and a 1/2A3-4T in t' sustainer. T' rocket flew up about 60 metres, weathercockin' toward t' south, thar be a slight pause, me hearties, then booster 1 ignited and booster 2 was ejected. Avast! Arrr! 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, matey, arched t' t' south, and dived straight down, itself in t' ground 20 metres south o' t' launch pad. Blimey! Blimey! T' sustainer's body tube be ripped and accordianed at t' front end. However, ya bilge rat, a bit o' maskin' tape and some smoothin' o' t' body tube prepared the sustainer for further flights. Begad! Well, blow me down! Upon examinin' t' engines o' both boosters and t' sustainer, ya bilge rat, I found that both boosters had exhausted themselves, but t' sustainer's engine be not ignited by booster 1's stagin' charge. Aye aye! Blimey! T' sustainer engine's base was blackened, shiver me timbers, arrr, so t' booster's stagin' charge must have activated. Avast! So, me hearties, t' determine whether t' stagin' engine was a dud, I pushed t' engine back into t' sustainer, matey, prepped it, ya bilge rat, and launched it. T' engine ignited. Blimey! Avast! Blimey! The sustainer flew straight up about 90 metres, popped its streamer, me hearties, and landed 25 metres east o' t' launch pad (the wind was shifting) with no damage. Ahoy! T' 40mm x 400mm streamer be far more effective in slowin' descent and bein' visible than t' 30mm x 300mm streamer was. I then prepared for a two-stage flight, matey, me hearties, me hearties, with an A10-0T in booster 1 and a 1/2A3-4T in t' sustainer. Begad! T' rocket flew straight up about 120 metres, matey, the sustainer ignited and ejected booster 1, me bucko, which tumbled t' earth about 10 metres northeast o' t' launch pad. Begad! Ahoy! T' sustainer flew up about 350 metres, popped its streamer, and descended t' land about 30 metres east o' t' launch pad. Blimey! This was a very pretty, me bucko, impressive flight. I then prepared for a three-stage flight again, with t' same configuration as t' first flight o' t' day. T' rocket flew straight up about 60 metres, then booster 1 be ignited and booster 2 was ejected. Blimey! Booster 2 tumbled and landed about 5 metres northeast o' t' launch pad. T' rocket flew up t' about 190 metres when t' sustainer be ignited and booster 1 be ejected. Booster 1 tumbled and landed about 20 metres east o' t' launchpad. Blimey! T' sustainer flew up out o' site and was invisible until it deployed its streamer. Blimey! T' sustainer finally landed about 60 metres east o' t' launch pad. |
Sponsored Ads
 |
 |