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, decided t' go for t' 2-stage approach with t' booster matchin' t' sustainer t' gain t' extra points. Ahoy! Well, blow me down! 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, arrr, shiver me timbers, so t' lower cone would be t' booster and fall away leavin' t' upper cone, outer rin' and fins for t' sustainer. Avast! Avast! T' rocket should be quite stable, arrr, as cones themselves are stable and thar are two largish fins, but only on one axis, arrr, so I’m goin' t' add some mass into t' nose for extra stability. 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, shiver me timbers, t' scale up factor was x5. Begad! Well, blow me down! 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. Begad! Blimey! A sheet o' card was rolled into a cone until t' length was 9 inches and t' base fitted the coupler. Avast!

A centerin' rin' was cut out o' card backed foam board t' accept a BT 20. Arrr! T' cone be sellotaped up and then attached t' t' coupler. Well, blow me down! Ahoy! This gave quite a sturdy cone. Well, blow me down! 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 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. Aye aye! Blimey! 10g o' clay be then added t' t' BT20 just behind t' nose cone. An 18mm engine block was glued into place so that t' aft motor would just stick out behind t' sustainer. Aye aye! 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. Avast, me proud beauty! 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. 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 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. Avast, me proud beauty! T' length o' t' cone was 3 inches. Ahoy! A centerin' rin' BT20 – BT50 was then added for a bit o' strength. Begad! An eye hook be then added so a streamer could be attached. Ya scallywag! 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. Well, blow me down! Begad! Blimey! T' rocket was covered in a mixture or wrinkles and blisters, ya bilge rat, and t' make matter worse, me bucko, this was 4 days before t' deadline. Aye aye! After sandin' as much o' t' damage away as possible I resprayed t' rocket, t' watch t' same thin' happen again, me bucko, I repeated this sand and spray process until t' blisterin' stopped, which was about 7 coats. Avast! Blimey! T' rocket was then sprayed with porcelain enamel paint. Ahoy! It does nay look great, but at a distance it is passable. Blimey! Blimey! After maskin' with tape, me hearties, black enamel highlights were added by brush. Blimey! Well, blow me down! Blimey!

I did nay bother addin' any clear coat or finish coat t' t' rocket.

Flight:
Flight one

Two Estes motors were used, ya bilge rat, shiver me timbers, matey, a B6-0, and a A8-3

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

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

Flight two

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

T' rocket was reassembled with a new ‘chute but no streamer. Begad! No new mass be added, me bucko, 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. Begad! Durin' t' 6 second coast phase t' rocket flew almost perfectly as a glider. Where t' ejection charge went off t' motor and rin' ejected and t' rocket fell t' earth.

T' parachute was again charred, ya bilge rat, me bucko, even though waddin' be used. Avast! Begad! However, shiver me timbers, matey, this was nay goin' t' be an issue for the next few flights. Aye aye! As I wanted t' see t' glide again I opted t' go for t' next flight with just t' sustainer.

Flight three

C6-0 (wrong motor choice)

Rocket lifted quite fast and be stable. Arrr! 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. Ahoy!

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. Arrr! Again at ejection t' motor popped and t' rocket fell. This time t' rocket damaged its aft fin. Begad!

I took t' rocket back t' be fixed with some 5 minutes epoxy. Ahoy! Givin' thought t' t' flights, shiver me timbers, I really wanted to use a 18mm plugged motor. As t' rocket seemed t' have a good CG, arrr, CP placement for a glider after t' motor had burned out (shouldn’t be stable for boost, me bucko, me bucko, 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. Begad! Avast, me proud beauty!

Flight five.

C6-0 - must ahave been a bilge-suckin' motor, appeared t' act like a plugged motor. Avast, me proud beauty!

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

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

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

Flight six

Two Estes motors were used, ya bilge rat, me bucko, a C6-0, and a C6-7. Begad! Arrr!

Flight was straight and stable, t' sustainer ignited with t' rocket pointin' about 10 degrees o' t' vertical. Booster recovered fine. Aye aye! 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, ya bilge rat, 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. Ya scallywag! Havin' said that, matey, 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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