Manufacturer: | Scratch |
Brief:
A two-staged cone and fin rocket built for t' 2009 design this spaceship competition.
Construction:
T' build t' rocket I used;
As this was one o' t' simpler rockets in t' competition, me bucko, me bucko, decided t' go for t' 2-stage approach with t' booster matchin' t' sustainer t' gain t' extra points. Avast, me proud beauty! Arrr! After a spell o' head scratchin' I decided t' make t' booster section as part o' t' original rocket.
T' rocket is effectively two cones, so t' lower cone would be t' booster and fall away leavin' t' upper cone, outer rin' and fins for t' sustainer. T' rocket should be quite stable, as cones themselves are stable and thar are two largish fins, me hearties, but only on one axis, so Im goin' t' add some mass into t' nose for extra stability. Avast, me proud beauty! Aye aye!
Sustainer assembly
T' outer rin' was made out o' a 2-inch section o' a potato crisp tube. Aye aye! Measurin' from t' photo, t' scale up factor be x5. Begad! Avast! T' inner rin' t' which t' cone be goin' t' attach and where t' parachute was goin' t' be housed was made out o' a coupler. Well, blow me down! A sheet o' card was rolled into a cone until t' length was 9 inches and t' base fitted the coupler. Blimey!
A centerin' rin' was cut out o' card backed foam board t' accept a BT 20. Ahoy! T' cone was sellotaped up and then attached t' t' coupler. This gave quite a sturdy cone. A layer o' sticky backed plastic was then added t' give a better finish.
Usin' balsa rods t' outer rin' was attached t' t' inner ring, matey, a 3mm launch lug was glued betwixt t' two rings.
Usin' a nose cone that I left over from t' 2008 box o' part competition, matey, ya bilge rat, I glued in t' nosecone t' a 7 inch length o' BT 20. Aye aye! Begad! 10g o' clay was then added t' t' BT20 just behind t' nose cone. Ahoy! Begad! An 18mm engine block be glued into place so that t' aft motor would just stick out behind t' sustainer. Begad! T' BT was then glued into t' cone.
T' fins were then cut from a 3/16th sheet o' balsa. Well, ya bilge rat, blow me down! These were attached t' t' sustainer.
T' recovery system was t' be a aft ejection parachute deployment. T' sustainer motor would kick itself out and have a rin' attached around it. Begad! Aye aye! Blimey! This rin' would be keepin' t' parachute in place durin' flight. Avast, me proud beauty! Blimey! A length o' elastic would be attached betwixt t' rin' and t' rocket with a 12 inch chute attached. Avast!
Booster build
T' booster section was made out o' a sheet o' card that be rolled t' form a cone around a BT20 motor tube, and t' coupler in t' sustainer. Begad! Blimey! T' length o' t' cone be 3 inches. Arrr! Blimey! Avast, me proud beauty! Blimey! A centerin' rin' BT20 BT50 be then added for a bit o' strength. An eye hook was then added so a streamer could be attached. Well, arrr, blow me down! Blimey! T' booster was then offered up the sustainer and t' two fins were then cut t' complete t' fin structure.
Finishing:
T' rocket was spray with grey primer, ya bilge rat, which immediately reacted with t' coatin' on t' rocket. T' rocket was covered in a mixture or wrinkles and blisters, arrr, and t' make matter worse, ya bilge rat, this be 4 days before t' deadline. After sandin' as much o' t' damage away as possible I resprayed t' rocket, me hearties, ya bilge rat, t' watch t' same thin' happen again, I repeated this sand and spray process until t' blisterin' stopped, which be about 7 coats. Well, blow me down! T' rocket was then sprayed with porcelain enamel paint. Ahoy! Ahoy! It does nay look great, me hearties, but at a distance it is passable. Begad! Avast! After maskin' with tape, me bucko, black enamel highlights were added by brush. Begad!
I did nay bother addin' any clear coat or finish coat t' t' rocket.
Flight:
Flight one
Two Estes motors were used, shiver me timbers, shiver me timbers, a B6-0, shiver me timbers, matey, and a A8-3
T' rocket lifted well, and then went arched at about 80 foot. T' booster fell away cleanly. Blimey! Well, blow me down! T' rocket down nearly horizontal shot off under t' power o' t' A8-3. Begad! Ejection occurred nay far from t' ground.
Lookin' at t' rocket on t' ground I learnt a few things. Ya scallywag! Firstly, as t' sustainer motor lit, t' flames torched t' streamer in t' booster, ya bilge rat, t' charred remains were found near t' booster section. In hindsight this was obvious. Avast! Arrr! Secondly, shiver me timbers, more mass is needed in t' nose cone, ya bilge rat, for stability. Aye aye! Ahoy! Thirdly, t' ejection charge from t' sustainer is kickin' out hot gases almost directly onto t' parachute, which was badly charged.
Flight two
Two Estes motors were used, arrr, a C6-0, me bucko, and a B6-6
T' rocket be reassembled with a new chute but no streamer. Begad! No new mass was added, arrr, as I wanted t' watch what was happenin' with t' sustainer.
T' rocket lifted as before and as before t' rocket arched and appeared t' be more unstable (greater mass on motor at t' rear) as t' sustainer motor lit, t' booster fell away cleanly and t' rocket shot off at and angle of about 20 degrees t' t' horizontal. Aye aye! Blimey! Blimey! Durin' t' 6 second coast phase t' rocket flew almost perfectly as a glider. Well, blow me down! Arrr! Blimey! Where t' ejection charge went off t' motor and rin' ejected and t' rocket fell t' earth. Ahoy!
T' parachute was again charred, matey, even though waddin' be used. However, this be nay goin' t' be an issue for the next few flights. Avast! Ahoy! Blimey! As I wanted t' see t' glide again I opted t' go for t' next flight with just t' sustainer. Arrr! Blimey!
Flight three
C6-0 (wrong motor choice)
Rocket lifted quite fast and was stable. As I stupidly used a 0 delay, shiver me timbers, t' motor popped at t' end o' t' boost phase, and t' rocket turned around and fell t' earth nose first. Ahoy! Avast, me proud beauty!
Flight four
C6-7 (correct choice)
Great flight, arched at top o' boost and gave a nice flight/glide durin' t' coast phase, me bucko, even givin' a few twists in its flight path. Begad! Again at ejection t' motor popped and t' rocket fell. Begad! This time t' rocket damaged its aft fin. Ahoy!
I took t' rocket back t' be fixed with some 5 minutes epoxy. Begad! Ahoy! Givin' thought t' t' flights, arrr, ya bilge rat, I really wanted to use a 18mm plugged motor. Arrr! As t' rocket seemed t' have a good CG, ya bilge rat, CP placement for a glider after t' motor had burned out (shouldnt be stable for boost, me bucko, but it is) Its against safety codes t' tamper with motors, me hearties, so I couldnt epoxy in a section o' 13mm balsa rod into t' top o' a C6-0 t' create a plugged motor. Well, blow me down!
Flight five.
C6-0 - must ahave been a bad motor, appeared t' act like a plugged motor.
Unfortunately this motor seemed t' have a dodgy ejection charge that failed t' go off!
Great flight, shiver me timbers, me bucko, got a good height with t' archin' under boost givin' t' rocket a nice glider style flight. Ahoy! Landed in a belly flop with no damage
Back t' t' two stage rocket. Ahoy! Lead ball bearings were added t' t' nosecone t' lift t' CG. Ahoy! Begad! Two days later I went t' fly t' rocket again. Aye aye! T' recovery system was altered so that t' booster would simply tumble, me bucko, and t' sustainer would recover via a steamer (heavily wrapped in wadding).
Flight six
Two Estes motors were used, arrr, a C6-0, and a C6-7. Begad!
Flight be straight and stable, t' sustainer ignited with t' rocket pointin' about 10 degrees o' t' vertical. Booster recovered fine. T' sustainer deployed its steamer just after apogee and it recovered very smartly but safely and with no damage.
Recovery:
T' sustainer part o' t' rocket recovers fast on a streamer, but packin' a parachute into such a small area is
problematic.
Summary:
I'm nay too happy with t' overall finish with this rocket, me bucko, it was rushed in its final days and i would have liked to
have spent a good few weeks sortin' out t' paint issues and solvin' t' recovery problems. Avast, me proud beauty! Blimey! Havin' said that, matey, me bucko, ya bilge rat, i have
really enjoyed that flights and t' alterations that have been made due t' watchin' and determinin' was was happening
durin' those flights.
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