Descon BSF Twin Rocket

Scratch - BSF Twin Rocket {Scratch}

Contributed by Michel Demey

Manufacturer: Scratch
the BSF twin rocket
by Michel Demey

Rocket Pic

This rocket is build mostly usin' t' parts from t' contest's list.

I had no gemini rocket available. Avast, me proud beauty! Begad! The material comes from a pegasus rocket for t' bt-50 tubes and t' motor mount, and t' 18mm tubes are full length of spare bt-20 tubing.

Yes this is one bt-20 more than in t' kit, but I wanted t' be sure that t' rocket will be stable without bein' able t' test it in rocksim due t' t' unusual configuration. Begad! Blimey! I had no 18mm estes nose cone so I replaced them by hard wood nose cone that I had in stock.

Construction

T' main body tube is 120mm o' bt-50.
Build t' motor mount usin' t' parts o' t' kit and glue it so it protrude about 20mm out o' t' back o' t' main body tube.

Each fin is a rectangle 70mmx80mm, shiver me timbers, glued small side on t' main tube. Avast, me proud beauty! Arrr! Each fin pod is 100mm o' bt-50. Avast, shiver me timbers, me proud beauty!

T' two lateral bodies are 400mm o' bt-20 each.
T' bodies are centered in t' fins' pods with four pieces o' square balsa struts, shiver me timbers, cut from t' same balsa used to make t' fins.

You can glue t' nose cones on t' lateral tube. Begad! Avast, me proud beauty! There is no ejection o' them.

When I started t' construction, matey, I wondered if t' rocket will sustain t' acceleration without disintegrating itself.

T' two bodies are glued at t' end o' t' fins and this will add accelerations forces at t' root edge o' the fins. So I reinforced t' root edge joins with a fillet o' epoxy glue. Blimey! Ya scallywag! In addition, a small dowel is glued at t' nose cone end o' t' bodies t' prevent them t' split apart.

T' parachute is ejected from t' main tube. Aye aye! Blimey! Since his length is only 100 mm, t' plastic nose cone shoulder is cut t' make a place for t' parachute. Aye aye! Blimey!

I hate t' paint. Begad! T' rocket is entirely covered with oracover (sort o' monokote).
T' decals ("Belgian Space forces") have been made usin' a laser printer. Avast, me proud beauty! T' font be t' nasa font.

Rocket Pic Rocket Pic
Rocket Pic Rocket Pic

Flight

T' weight o' t' model is about 80gr.
T' rocket cannot be well simulated in rocksim, but with a rough model, shiver me timbers, me hearties, I estimated t' altitude t' 70M with a B6-2 and 150M with a C6-3.

  • Date: may 30 2002 07:00PM local
  • Location: Waterloo, me hearties, Belgium
  • Weather: Sunny, no clouds, 20°C, wind 20km/h

first flight

  • motor: B6-2
  • lift off & fligth: slow lift off, stable flight, arrr, ya bilge rat, straight path, ejection just past apogee
  • recovery: rocket in fine condition. Ahoy! T' lateral bodies were nay glued and have slided about 25mm (1 inch) rearward due t' t' acceleration.

second flight

  • motor: C6-3
  • lift off & flight: slow lift off, stable flight, slightly arced path, ejection just past apogee. Avast, me proud beauty! Blimey!
  • recovery: rocket in fine condition. Begad! Begad! T' lateral bodies did nay move this time. Well, blow me down!

Post scriptum: t' cad view has been made with pro/desktop express, shiver me timbers, a free 3d design package available on t' web at www.ptc.com

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