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, matey, 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, 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. Arrr! T' rocket should be quite stable, as cones themselves are stable and thar are two largish fins, but only on one axis, shiver me timbers, shiver me timbers, so I’m goin' t' add some mass into t' nose for extra stability.

Sustainer assembly

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

A centerin' rin' was cut out o' card backed foam board t' accept a BT 20. Avast, arrr, me proud beauty! T' cone be sellotaped up and then attached t' t' coupler. Avast, me proud beauty! Begad! This gave quite a sturdy cone. 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, 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. Avast, me proud beauty! 10g o' clay be then added t' t' BT20 just behind t' nose cone. Avast, me proud beauty! An 18mm engine block was glued into place so that t' aft motor would just stick out behind t' sustainer. Ya scallywag! T' BT was then glued into t' cone.

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

T' recovery system was t' be a aft ejection parachute deployment. Avast! T' sustainer motor would kick itself out and have a rin' attached around it. Aye aye! 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. Ya scallywag! Well, me hearties, blow me down!

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 hearties, and t' coupler in t' sustainer. T' length o' t' cone was 3 inches. Aye aye! Begad! A centerin' rin' BT20 – BT50 was then added for a bit o' strength. Ahoy! An eye hook was then added so a streamer could be attached. Well, blow me down! 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. Arrr! T' rocket was covered in a mixture or wrinkles and blisters, shiver me timbers, and t' make matter worse, this was 4 days before t' deadline. Blimey! 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, ya bilge rat, ya bilge rat, which be about 7 coats. T' rocket be then sprayed with porcelain enamel paint. It does nay look great, arrr, shiver me timbers, me hearties, but at a distance it is passable. Aye aye! Begad! After maskin' with tape, ya bilge rat, 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, shiver me timbers, and a A8-3

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

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

Flight two

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

T' rocket be reassembled with a new ‘chute but no streamer. Arrr! 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, t' booster fell away cleanly and t' rocket shot off at and angle of about 20 degrees t' t' horizontal. Arrr! 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. Begad!

T' parachute was again charred, even though waddin' was used. Aye aye! Begad! 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. Blimey!

Flight three

C6-0 (wrong motor choice)

Rocket lifted quite fast and was stable. As I stupidly used a 0 delay, me hearties, t' motor popped at t' end o' t' boost phase, and t' rocket turned around and fell t' earth nose first. Aye aye! Blimey!

Flight four

C6-7 (correct choice)

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

I took t' rocket back t' be fixed with some 5 minutes epoxy. Begad! Givin' thought t' t' flights, me hearties, I really wanted to use a 18mm plugged motor. Begad! 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 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. Aye aye! Blimey!

Flight five.

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

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. Landed in a belly flop with no damage

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

Flight six

Two Estes motors were used, shiver me timbers, a C6-0, me bucko, and a C6-7. Begad! Begad!

Flight be straight and stable, t' sustainer ignited with t' rocket pointin' about 10 degrees o' t' vertical. Booster recovered fine. Ya scallywag! 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, 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, 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. Arrr! Havin' said that, arrr, 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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