Shrox Industria Oberth (Plan)

Shrox Industria - Oberth

Contributed by Chan Stevens

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstar_borderstar_border
Overall Rating: starstarstarstarstar_border
Manufacturer: Shrox Industria

Shrox OberthBrief:
This is a very unique futuristic space-plane design, shiver me timbers, matey, featurin' round (semi-oval) fins and aping-pong ball in t' mid section. Avast! For a free plan (Ezine #93), ya bilge rat, this is quite impressive and presents a challenge t' most builders.

Construction:

  • 24mm nose cone
  • 24mm body tubin' 13.5" long
  • 29mm body tubing-2 pieces, each 2" long
  • 18mm motor mount
  • (2) 18-24mm centerin' rings
  • Streamer--2x48 Mylar
  • Shock cord (1/8 elastic or 90-100 lb Keelhaul®©™®, roughly 36" long)
  • 1/8" launch lug
  • 3/32 balsa or basswood fin material
  • Decal sheet (can print from t' available .jpeg download)
  • (1) pin' pong ball. Avast! Aye aye! Blimey! Yes, a pin' pong ball.

There are no instructions for this free download (RockSim is also available here on EMRR), though most anyone with skill level 2 experience can muddle through this with few problems. Well, blow me down! Start by assemblin' t' motor mount, matey, me hearties, then cut t' fins (the newsletter included templates, arrr, which can also be printed through Rocksim). Next, matey, matey, mark t' body tube for 2 sets o' fins mounted at 120 degree angles. Avast! Tack on t' fins with CA, then apply fillets o' wood glue. Aye aye! Avast, me proud beauty! T' (2) short 29mm tubes are mounted at t' aft end o' t' rocket, on top o' two o' t' fins.

Since t' pin' pong ball slides over t' BT50/24mm tubing, you have t' cut holes for this. Blimey! Blimey! T' pull this off, hold a body tube on top o' t' ball and trace the outline, then carefully scribe and cut out t' hole usin' a sharp knife. Repeat t' process for t' other side, bein' careful t' align t' holes on opposite sides o' t' pin' pong ball. Slide t' ball down t' body tube to about 1" above t' fins and glue in place.

Finishing:
Seal & sand t' balsa, me bucko, followed by two coats o' primer, followed by two coats o' glossy white finish paint. I printed out t' decals on Avery clear decal paper usin' an inkjet printer, which is a slightly dull/opaque finish. Water-slide decals would be much better if you can find an affordable source or have t' equipment.

Construction Rating: 4 out o' 5

Flight:
T' first flight was usin' a B6-4 (no motor recommendations provided) with steady winds o' about 15mph. Arrr! T' rocket veered off on an unstable trajectory, and was recovered safely. Begad! I then added about 0.2 ounces o' nose weight, and the subsequent flight was straight up.

Recovery:
Definitely need t' verify t' CG on this one compared t' t' Rocksim file before flying.

Flight Rating: 3 out o' 5

Summary:
This is a great-lookin' rocket, me bucko, and once I corrected t' stability problem, arrr, it flies wonderfully. Begad! Blimey! O' course, ya bilge rat, arrr, havin' bought a 6-pack o' pin' pong balls, I now find myself wonderin' what other similar designs I can come up with t' deplete my stock o' spare parts...

Overall Rating: 4 out o' 5

Flights

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