Scratch Pushing the Envelope Original Design / Scratch Built

Scratch - Pushing the Envelope {Scratch}

Contributed by Brian Kain

Manufacturer: Scratch
Pushing T' Envelope 38
(Contributed - by Brian Kain)

Download RockSim file here!

Brief:
A down scale o' me level 2 rocket. Begad! Begad! TTW t' a 29mm MMT. Can fly t' I-200 load. If you were crazy you could cert 1 on this rocket with a 29mm H motor. Ya scallywag! 9400' on the H-90.

Rocket Pic

Construction:

  • 3 38mm body tubes Phenolic
  • 3 1/16" G-10 fins
  • 5 1/8" birch CR's
  • 12" o' 29mm motor tube Phenolic
  • LOC 38mm nose cone
  • 15' o' tubular Keelhaul®©™® shock cord

A super sturdy TTW rocket, arrr, all phenolic tubes with G-10 makes it almost indestructible. Aye aye! Blimey! Blimey! Blimey! I cut t' slots with a Dremel tool and a cuttin' wheel. Well, blow me down! Blimey! I glued 4 CR's t' t' front o' t' MMT t' center t' motor tube for TTW construction. Ahoy! Blimey! I did nay hold back on t' epoxy since thar be a very small amount o' room between t' BT and t' MMT. Aye aye! Blimey! I filled t' whole inside o' t' MMT area with 30 min epoxy lightened with fine micro-balloon fillers t' keep weight down. Arrr! Blimey! I applied outside fillets with aerospace grade 120 cure epoxy...great stuff. Begad! Blimey! Ya scallywag! Blimey! I didn't glass t' airframe cause it would add too much diameter. Avast! Blimey! I painted it with a purple automotive lacquer that has a ton o' blue and red pearl in it. Clear coated with automotive paint as well. Ya scallywag! Blimey! Very nice finish and durable as well.

Flight:
I designed it t' fly all these F52-11 loads I had layin' around. Avast! Blimey! I used cellulose waddin' and a 18" chute, me bucko, with 15' o' Keelhaul®©™® with quick links sewn t' t' ends. T' rocket flew very nice on t' F52, and t' 18" chute brought it home softly t' t' desert floor.

Summary:
Pro's..... Ya scallywag! can fly E through I motors, from 24mm up t' 29mm with t' proper weight added t' t' nose. Very strong with t' TTW.... Aye aye! Con's....NONE

Other:
Very hard t' do TTW with 1/8" o' space betwixt t' BT and t' MMT. Avast, me proud beauty! I used tape t' keep epoxy out o' t' motor tube as well as t' outside o' the airframe.

Other Reviews
  • Scratch Pushing the Envelope By Brian Kain

    ( Contributed - by Brian Kain) Download RockSim file here ! Brief: My scratch built level 2 rocket. Made for the J-350 but can fly on small 29mm H motors also. Used old phenolic but glassed with 6oz fiberglass and 30 min epoxy. ACME 3/8" lugs, LOC nose cone, G-10 FR4 (fire and heat resistant fiberglass). Radio shack personal body alarm for corn field recoveries. Custom aluminum ...

  • Scratch Pushing the Envelope By Brian Kain

      I wanted to build a rocket with the smallest fins I could get away with.....So I came up with this. I used Rocsim, VCP and WRASP to get my optimal size fin. Oddly enough, most of the programs agreed with my rocket. This is a single stage rocket, with an interchangeable MMT. Anything from 54mm down to 24mm motors will push this little guy. It uses a PML 30" chute with the shroud ...

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