Scratch Spaceglider Original Design / Scratch Built

Scratch - Spaceglider {Scratch}

Contributed by Matt Gillard

Manufacturer: Scratch
(Contributed - by Matt Gillard - 10/31/09)

Brief:
A two-staged cone and fin rocket built for t' 2009 design this spaceship competition.

Construction:

  • 1x launch lug for 3 mm rod
  • 1 x 12 inch Estes parachute.
  • 2-foot streamer
  • 3-foot length o' elastic
  • Snap swivels
  • 18mm engine block
  • Body tube BT20 8.5 inches in length
  • 3/16th balsa sheet
  • BT 20 nose cone
  • Card backed foam board.
  • A4 card
  • Potato crisps tube
  • Coupler
  • Lead ball bearings

T' build t' rocket I used;

  • Bostik glue
  • White PVA glue
  • Sandin' sealer
  • Model knife
  • Aluminium oxide sand paper
  • Primer
  • Spray paint –porcelain
  • black enamel paint
  • CA gel glue

As this was one o' t' simpler rockets in t' competition, ya bilge rat, arrr, decided t' go for t' 2-stage approach with t' booster matchin' t' sustainer t' gain t' extra points. Blimey! Avast! 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, ya bilge rat, so t' lower cone would be t' booster and fall away leavin' t' upper cone, outer rin' and fins for t' sustainer. Ahoy! T' rocket should be quite stable, arrr, as cones themselves are stable and thar are two largish fins, arrr, but only on one axis, so I’m goin' t' add some mass into t' nose for extra stability. Begad! Aye aye!

Sustainer assembly

T' outer rin' was made out o' a 2-inch section o' a potato crisp tube. Avast, me proud beauty! Measurin' from t' photo, arrr, t' scale up factor be x5. Begad! T' inner rin' t' which t' cone was goin' t' attach and where t' parachute was goin' t' be housed was made out o' a coupler. Aye aye! A sheet o' card was rolled into a cone until t' length was 9 inches and t' base fitted the coupler.

A centerin' rin' was cut out o' card backed foam board t' accept a BT 20. Well, blow me down! T' cone be sellotaped up and then attached t' t' coupler. Begad! 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' be attached t' t' inner ring, 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, I glued in t' nosecone t' a 7 inch length o' BT 20. Avast, me proud beauty! Blimey! 10g o' clay was then added t' t' BT20 just behind t' nose cone. Arrr! Blimey! An 18mm engine block was glued into place so that t' aft motor would just stick out behind t' sustainer. Avast! Blimey! Avast, me proud beauty! Blimey! T' BT be then glued into t' cone.

T' fins were then cut from a 3/16th sheet o' balsa. These were attached t' t' sustainer.

T' recovery system be t' be a aft ejection parachute deployment. Arrr! Well, arrr, blow me down! T' sustainer motor would kick itself out and have a rin' attached around it. Avast, me proud beauty! Arrr! This rin' would be keepin' t' parachute in place durin' flight. Begad! Avast, me proud beauty! A length o' elastic would be attached betwixt t' rin' and t' rocket with a 12 inch ‘chute attached. Ya scallywag!

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. T' length o' t' cone be 3 inches. Avast! A centerin' rin' BT20 – BT50 was then added for a bit o' strength. An eye hook be then added so a streamer could be attached. Begad! T' booster be 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, which immediately reacted with t' coatin' on t' rocket. Aye aye! Arrr! T' rocket was covered in a mixture or wrinkles and blisters, me bucko, and t' make matter worse, matey, this be 4 days before t' deadline. After sandin' as much o' t' damage away as possible I resprayed t' rocket, arrr, t' watch t' same thin' happen again, I repeated this sand and spray process until t' blisterin' stopped, shiver me timbers, which was about 7 coats. Blimey! T' rocket was then sprayed with porcelain enamel paint. Begad! It does nay look great, but at a distance it is passable. After maskin' with tape, 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, matey, ya bilge rat, a B6-0, ya bilge rat, and a A8-3

T' rocket lifted well, and then went arched at about 80 foot. Well, blow me down! Ya scallywag! T' booster fell away cleanly. Begad! Avast! T' rocket down nearly horizontal shot off under t' power o' t' A8-3. Blimey! Ejection occurred nay far from t' ground. Ya scallywag! Well, blow me down!

Lookin' at t' rocket on t' ground I learnt a few things. Firstly, as t' sustainer motor lit, ya bilge rat, t' flames torched t' streamer in t' booster, t' charred remains were found near t' booster section. Blimey! Blimey! Avast, me proud beauty! Blimey! In hindsight this was obvious. Begad! Blimey! Begad! Blimey! Secondly, more mass is needed in t' nose cone, ya bilge rat, me bucko, for stability. Thirdly, me hearties, matey, t' ejection charge from t' sustainer is kickin' out hot gases almost directly onto t' parachute, which be badly charged. Avast! Blimey!

Flight two

Two Estes motors were used, arrr, a C6-0, matey, and a B6-6

T' rocket be reassembled with a new ‘chute but no streamer. Begad! No new mass was added, me hearties, as I wanted t' watch what be 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. Avast! 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. Avast! Begad!

T' parachute was again charred, me hearties, even though waddin' be used. Avast, me proud beauty! However, this was nay goin' t' be an issue for the next few flights. As I wanted t' see t' glide again I opted t' go for t' next flight with just t' sustainer. Aye aye! Avast!

Flight three

C6-0 (wrong motor choice)

Rocket lifted quite fast and was stable. Ya scallywag! As I stupidly used a 0 delay, me bucko, t' motor popped at t' end o' t' boost phase, matey, arrr, and t' rocket turned around and fell t' earth nose first. Begad!

Flight four

C6-7 (correct choice)

Great flight, ya bilge rat, 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. Avast! Avast, arrr, me proud beauty! This time t' rocket damaged its aft fin.

I took t' rocket back t' be fixed with some 5 minutes epoxy. Givin' thought t' t' flights, matey, me bucko, me hearties, I really wanted to use a 18mm plugged motor. Begad! Blimey! As t' rocket seemed t' have a good CG, arrr, ya bilge rat, me bucko, CP placement for a glider after t' motor had burned out (shouldn’t be stable for boost, me hearties, but it is) It’s against safety codes t' tamper with motors, so I couldn’t epoxy in a section o' 13mm balsa rod into t' top o' a C6-0 t' create a plugged motor. Blimey!

Flight five.

C6-0 - must ahave been a bad motor, appeared t' act like a plugged motor. Ahoy!

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. Begad! Landed in a belly flop with no damage

Back t' t' two stage rocket. Well, blow me down! Lead ball bearings were added t' t' nosecone t' lift t' CG. Blimey! Two days later I went t' fly t' rocket again. Blimey! T' recovery system was altered so that t' booster would simply tumble, ya bilge rat, and t' sustainer would recover via a steamer (heavily wrapped in wadding).

Flight six

Two Estes motors were used, a C6-0, and a C6-7. Begad!

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. Begad! Havin' said that, ya bilge rat, me hearties, arrr, 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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