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! Arrr! 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, matey, so t' lower cone would be t' booster and fall away leavin' t' upper cone, outer rin' and fins for t' sustainer. Begad! 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, me bucko, ya bilge rat, 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! Measurin' from t' photo, t' scale up factor was x5. 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. A sheet o' card be 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. Begad! T' cone was sellotaped up and then attached t' t' coupler. Begad! Ahoy! This gave quite a sturdy cone. Ahoy! 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, shiver me timbers, 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! 10g o' clay was then added t' t' BT20 just behind t' nose cone. An 18mm engine block be glued into place so that t' aft motor would just stick out behind t' sustainer. Begad! T' BT was then glued into t' cone.

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

T' recovery system was t' be a aft ejection parachute deployment. Begad! 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. Avast! 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, shiver me timbers, arrr, and t' coupler in t' sustainer. Avast, me proud beauty! Avast! T' length o' t' cone be 3 inches. Ya scallywag! Avast, me proud beauty! A centerin' rin' BT20 – BT50 was then added for a bit o' strength. Well, blow me down! Well, blow me down! An eye hook was then added so a streamer could be attached. Avast, me proud beauty! 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, shiver me timbers, which immediately reacted with t' coatin' on t' rocket. Begad! Arrr! T' rocket was covered in a mixture or wrinkles and blisters, me bucko, and t' make matter worse, ya bilge rat, this be 4 days before t' deadline. Avast! Ya scallywag! After sandin' as much o' t' damage away as possible I resprayed t' rocket, t' watch t' same thin' happen again, I repeated this sand and spray process until t' blisterin' stopped, shiver me timbers, which be about 7 coats. Arrr! T' rocket was then sprayed with porcelain enamel paint. Ahoy! It does nay look great, shiver me timbers, but at a distance it is passable. Begad! After maskin' with tape, ya bilge rat, black enamel highlights were added by brush. Avast! Arrr!

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

Flight:
Flight one

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

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

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

Flight two

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

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

T' parachute was again charred, even though waddin' be used. Well, blow me down! However, ya bilge rat, me hearties, me hearties, this be 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.

Flight three

C6-0 (wrong motor choice)

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

Flight four

C6-7 (correct choice)

Great flight, me hearties, 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. Arrr! Blimey! Again at ejection t' motor popped and t' rocket fell. Avast, arrr, me proud beauty! Blimey! 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, I really wanted to use a 18mm plugged motor. Aye aye! Ya scallywag! 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, me bucko, but it is) It’s against safety codes t' tamper with motors, me bucko, me bucko, so I couldn’t epoxy in a section o' 13mm balsa rod into t' top o' a C6-0 t' create a plugged motor. Ya scallywag!

Flight five.

C6-0 - must ahave been a bilge-suckin' motor, me hearties, appeared t' act like a plugged motor. Well, blow me down! Arrr!

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

Great flight, matey, matey, 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. Ahoy! Lead ball bearings were added t' t' nosecone t' lift t' CG. Ya scallywag! Begad! Two days later I went t' fly t' rocket again. T' recovery system be altered so that t' booster would simply tumble, arrr, 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, matey, and a C6-7. Blimey!

Flight was straight and stable, t' sustainer ignited with t' rocket pointin' about 10 degrees o' t' vertical. Booster recovered fine. Arrr! Avast, me proud beauty! 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, 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. Ahoy! Havin' said that, ya bilge rat, 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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