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