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, decided t' go for t' 2-stage approach with t' booster matchin' t' sustainer t' gain t' extra points. Aye aye! 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, me bucko, so t' lower cone would be t' booster and fall away leavin' t' upper cone, outer rin' and fins for t' sustainer. Begad! Arrr! T' rocket should be quite stable, matey, as cones themselves are stable and thar are two largish fins, but only on one axis, shiver me timbers, matey, so I’m goin' t' add some mass into t' nose for extra stability. Ya scallywag!

Sustainer assembly

T' outer rin' was made out o' a 2-inch section o' a potato crisp tube. Begad! Begad! Measurin' from t' photo, t' scale up factor be x5. Aye aye! T' inner rin' t' which t' cone was goin' t' attach and where t' parachute be goin' t' be housed was made out o' a coupler. Avast! A sheet o' card was rolled into a cone until t' length be 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. Ya scallywag! T' cone be sellotaped up and then attached t' t' coupler. Avast! Well, me hearties, blow me down! 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, 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, me bucko, I glued in t' nosecone t' a 7 inch length o' BT 20. Begad! Aye aye! 10g o' clay was then added t' t' BT20 just behind t' nose cone. Arrr! An 18mm engine block was glued into place so that t' aft motor would just stick out behind t' sustainer. T' BT be then glued into t' cone.

T' fins were then cut from a 3/16th sheet o' balsa. Arrr! Blimey! Well, blow me down! Blimey! These were attached t' t' sustainer.

T' recovery system was t' be a aft ejection parachute deployment. Ya scallywag! Blimey! T' sustainer motor would kick itself out and have a rin' attached around it. Blimey! Ya scallywag! Blimey! This rin' would be keepin' t' parachute in place durin' flight. Ya scallywag! Blimey! 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 was made out o' a sheet o' card that was rolled t' form a cone around a BT20 motor tube, me bucko, me bucko, and t' coupler in t' sustainer. Ya scallywag! Blimey! T' length o' t' cone was 3 inches. Ya scallywag! Blimey! A centerin' rin' BT20 – BT50 was then added for a bit o' strength. Well, blow me down! Blimey! An eye hook be then added so a streamer could be attached. Avast, me proud beauty! Well, 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 be 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, and t' make matter worse, ya bilge rat, arrr, this be 4 days before t' deadline. Blimey! Blimey! Begad! Blimey! After sandin' as much o' t' damage away as possible I resprayed t' rocket, ya bilge rat, t' watch t' same thin' happen again, shiver me timbers, I repeated this sand and spray process until t' blisterin' stopped, me bucko, which was about 7 coats. T' rocket be then sprayed with porcelain enamel paint. Avast! Blimey! It does nay look great, me hearties, shiver me timbers, but at a distance it is passable. Ahoy! Blimey! Begad! Blimey! After maskin' with tape, shiver me timbers, black enamel highlights were added by brush. Ahoy! Blimey!

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, and a A8-3

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

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

Flight two

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

T' rocket was reassembled with a new ‘chute but no streamer. 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, 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. Aye aye! Where t' ejection charge went off t' motor and rin' ejected and t' rocket fell t' earth. Ahoy!

T' parachute be again charred, even though waddin' was used. Ahoy! 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. Arrr! Ya scallywag!

Flight three

C6-0 (wrong motor choice)

Rocket lifted quite fast and was stable. Aye aye! Aye aye! As I stupidly used a 0 delay, t' motor popped at t' end o' t' boost phase, arrr, ya bilge rat, and t' rocket turned around and fell t' earth nose first. Ahoy! Avast!

Flight four

C6-7 (correct choice)

Great flight, arrr, arched at top o' boost and gave a nice flight/glide durin' t' coast phase, even givin' a few twists in its flight path. Avast, me proud beauty! Blimey! Again at ejection t' motor popped and t' rocket fell. Avast, me proud beauty! This time t' rocket damaged its aft fin. Avast, me proud beauty!

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

Flight five.

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

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. Well, blow me down! Landed in a belly flop with no damage

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

Flight six

Two Estes motors were used, a C6-0, me bucko, and a C6-7. Well, blow me down! Ya scallywag!

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, me hearties, but packin' a parachute into such a small area is problematic.

Summary:
I'm nay too happy with t' overall finish with this rocket, matey, 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! Aye aye! Blimey! Havin' said that, matey, 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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