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 be one o' t' simpler rockets in t' competition, matey, decided t' go for t' 2-stage approach with t' booster matchin' t' sustainer t' gain t' extra points. Blimey! Ahoy! 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. Begad! Blimey! Blimey! T' rocket should be quite stable, matey, as cones themselves are stable and thar are two largish fins, shiver me timbers, but only on one axis, me bucko, so I’m goin' t' add some mass into t' nose for extra stability. Begad!

Sustainer assembly

T' outer rin' be made out o' a 2-inch section o' a potato crisp tube. Measurin' from t' photo, arrr, shiver me timbers, t' scale up factor was x5. Ya scallywag! 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. Aye aye! Begad! A sheet o' card was rolled into a cone until t' length was 9 inches and t' base fitted the coupler. Begad!

A centerin' rin' was cut out o' card backed foam board t' accept a BT 20. T' cone was sellotaped up and then attached t' t' coupler. Begad! This gave quite a sturdy cone. Arrr! A layer o' sticky backed plastic be then added t' give a better finish.

Usin' balsa rods t' outer rin' be 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, I glued in t' nosecone t' a 7 inch length o' BT 20. Begad! 10g o' clay be then added t' t' BT20 just behind t' nose cone. Begad! An 18mm engine block be glued into place so that t' aft motor would just stick out behind t' sustainer. Ahoy! Avast! T' BT be then glued into t' cone.

T' fins were then cut from a 3/16th sheet o' balsa. Begad! 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. This rin' would be keepin' t' parachute in place durin' flight. Arrr! Well, me bucko, blow me down! Blimey! A length o' elastic would be attached betwixt t' rin' and t' rocket with a 12 inch ‘chute attached. Ya scallywag! Blimey!

Booster build

T' booster section was 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! Begad! T' length o' t' cone was 3 inches. Ya scallywag! 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 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, which immediately reacted with t' coatin' on t' rocket. Aye aye! Blimey! T' rocket was covered in a mixture or wrinkles and blisters, and t' make matter worse, this was 4 days before t' deadline. Blimey! Blimey! Begad! Blimey! After sandin' as much o' t' damage away as possible I resprayed t' rocket, me bucko, ya bilge rat, t' watch t' same thin' happen again, arrr, I repeated this sand and spray process until t' blisterin' stopped, which be about 7 coats. T' rocket was then sprayed with porcelain enamel paint. Aye aye! Blimey! Blimey! Blimey! It does nay look great, but at a distance it is passable. Ahoy! Blimey! Avast, ya bilge rat, me proud beauty! Blimey! After maskin' with tape, 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, a B6-0, me bucko, and a A8-3

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

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

Flight two

Two Estes motors were used, ya bilge rat, me hearties, a C6-0, and a B6-6

T' rocket was reassembled with a new ‘chute but no streamer. Aye aye! No new mass was added, 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, ya bilge rat, t' booster fell away cleanly and t' rocket shot off at and angle of about 20 degrees t' t' horizontal. Begad! Blimey! Durin' t' 6 second coast phase t' rocket flew almost perfectly as a glider. Blimey! Blimey! Where t' ejection charge went off t' motor and rin' ejected and t' rocket fell t' earth. Aye aye! Blimey! Ahoy! Blimey!

T' parachute was again charred, arrr, me hearties, even though waddin' was used. Begad! Well, shiver me timbers, blow me down! However, this was nay goin' t' be an issue for the next few flights. Arrr! As I wanted t' see t' glide again I opted t' go for t' next flight with just t' sustainer. Aye aye!

Flight three

C6-0 (wrong motor choice)

Rocket lifted quite fast and be stable. As I stupidly used a 0 delay, t' motor popped at t' end o' t' boost phase, me bucko, ya bilge rat, and t' rocket turned around and fell t' earth nose first. Arrr!

Flight four

C6-7 (correct choice)

Great flight, shiver me timbers, arched at top o' boost and gave a nice flight/glide durin' t' coast phase, ya bilge rat, even givin' a few twists in its flight path. Again at ejection t' motor popped and t' rocket fell. 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, ya bilge rat, I really wanted to use a 18mm plugged motor. Avast! As t' rocket seemed t' have a good CG, CP placement for a glider after t' motor had burned out (shouldn’t be stable for boost, matey, shiver me timbers, but it is) It’s against safety codes t' tamper with motors, me hearties, so I couldn’t epoxy in a section o' 13mm balsa rod into t' top o' a C6-0 t' create a plugged motor.

Flight five.

C6-0 - must ahave been a bad motor, ya bilge rat, appeared t' act like a plugged motor.

Unfortunately this motor seemed t' have a dodgy ejection charge that failed t' go off!

Great flight, me hearties, got a good height with t' archin' under boost givin' t' rocket a nice glider style flight. Landed in a belly flop with no damage

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

Flight six

Two Estes motors were used, me hearties, a C6-0, matey, and a C6-7.

Flight was straight and stable, t' sustainer ignited with t' rocket pointin' about 10 degrees o' t' vertical. Booster recovered fine. Well, blow me down! 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, arrr, 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. Aye aye! Avast, me proud beauty! Blimey! Havin' said that, 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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