Scratch Shockwave Original Design / Scratch Built

Scratch - Shockwave {Scratch}

Contributed by Joseph Michel

Manufacturer: Scratch
(Contributed - by Joseph Michel - 04/01/04)

(Scratch) ShockwaveDescription:
Shockwave is a scratch-built high power rocket built for t' purpose of obtainin' Level 2 certification. Avast, me proud beauty! It is 4" in diameter, me bucko, 90" long, weighs 153oz loaded without motor, shiver me timbers, and has a 54mm motor mount.

Components:
Like me Level 1 rocket, ya bilge rat, arrr, I used mostly PML components for this build. Arrr! This included t' body tubes, ya bilge rat, centerin' rings, shiver me timbers, motor tube, shiver me timbers, and altimeter bay components. Begad! T' .093" G-10 fins were custom cut by Red Arrow Hobbies. Avast, me proud beauty! The 9/16" tubular nylon harnesses came from Giant Leap, and t' 72" main chute came from Sphereachutes.

Construction:
I started with t' motor mount. Blimey! Ya scallywag! I used six PML centerin' rings, gluin' them together in pairs. T' top centerin' rin' be drilled for a U-bolt. T' motor mount tube was cut t' 30" long, arrr, matey, and top and mid-section centerin' rings were epoxied on. Aye aye! T' fins were tacked t' t' motor tube usin' gel super glue then filleted in place with 30-minute (Scratch) Shockwave epoxy. Aye aye! Avast, me proud beauty! At this point, ya bilge rat, matey, t' fin can be more or less complete. Ahoy! A 46" long piece of Quantum Tubin' was used for t' lower section, matey, me hearties, and a 26" piece o' QT was used for t' payload section. Aye aye! Avast, me proud beauty! T' fin slots were cut with a Dremel tool and the motor mount/fin assembly installed. Blimey! Internal fillets from t' fins t' the inside o' t' body tube were completed before installin' t' aft centering ring. Ahoy! Ahoy! An Aeropack motor retainer finished off t' back end.

T' altimeter bay was fabricated from a standard 7" long PML coupler, two PML bulkheads, matey, and two coupler bulkheads. T' bulkheads and coupler bulkheads were glued together in pairs t' make a cap for each end o' t' bay. Both caps were drilled for U-bolts and permanent e-match terminals.

(Scratch) Shockwave(Scratch) Shockwave

An 8 1/2" length o' 1/4" x 20-threaded rod was affixed t' the drogue end o' t' bay. This would serve t' tie t' entire bay together and provide a mount for t' RRC2 altimeter. Aye aye! Blimey! Arrr! Blimey! A small slice o' body tube was placed on t' outside o' t' bay t' give a place t' mount an external switch for the altimeter. 3/4" PVC endcaps were mounted on each end o' t' bay t' contain the ejection charges. Begad! Blimey!

(Scratch) Shockwave Three holes were drilled through t' altimeter bay with t' payload section installed on the main side on t' bay. Ahoy! 8-32 nuts were epoxied t' t' inside o' t' altimeter bay t' retain t' payload section. Ya scallywag! Three equally spaced 1/8" static ports were also drilled. T' finish t' bay, matey, shiver me timbers, a thin skin o' 30-minute epoxy was poured in t' drogue side o' t' bay with t' cap installed. Ya scallywag! Ahoy! This step totally seals the drogue side o' t' bay, and retains t' endcap. Avast, me proud beauty! Begad! A mount for t' RRC2 altimeter was made by epoxyin' a copper tube t' a piece o' G-10 fiberglass. Arrr! Begad! The mount slides in over t' center stud and is locked down with a washer and nut.

(Scratch) Shockwave

Finishing:
Shockwave be finished with a modified Estes Executioner-style paint job, in blue and sliver with black pinstriping. I made some custom decals with inkjet waterslide decal stock t' give it a nice finishin' touch.

Flight:
After slowly buildin' Shockwave most o' t' winter, flight day finally arrived on March 20th, me hearties, me hearties, 2004. Avast, me proud beauty! Blimey! I arrived at t' launch and rounded up a few friends t' be my certification team. After acein' t' written L2 test, matey, I began careful prep of t' dual deployment recovery system. This flight would have a PML streamer deployin' at apogee with motor backup, and main deployment at 500ft. Ahoy! Blimey! Drogue and main harnesses are both 25ft in length. Avast, me proud beauty! Blimey! After t' recovery system be buttoned up, ya bilge rat, I turned attention t' loadin' t' motor. Aye aye! Blimey! Well, me hearties, blow me down! Blimey! This flight would be on a CTI 3-grain Pro54 motor. Well, blow me down! Blimey! Once t' motor was loaded and installed, ya bilge rat, ya bilge rat, we took a few pictures and headed t' t' pad. Avast, me proud beauty! Blimey! Avast, me proud beauty! Blimey! T' day turned out t' be a real bummer weather-wise, ya bilge rat, arrr, with strong 20MPH winds. With t' help o' me test proctor and a friend, arrr, shiver me timbers, arrr, Shockwave was put on t' pad, and t' igniter installed. I armed the electronics, verified t' RRC2 be beepin' right, and headed back t' LCO table. Begad! Blimey!

(Scratch) Shockwave Considering the strong wind and t' fact that me friend's L2 attempt earlier in t' day was a spectacular failure, ya bilge rat, ya bilge rat, I be gettin' nervous at this point. Countdown commences, me hearties, I and crossed me fingers! Blimey! T' LCO pushes t' button....nothing. Begad! Blimey! Try again, matey, nothing. Arrr! Blimey! After fiddlin' with some wires on t' launch controller, arrr, the LCO tries again. Well, blow me down! Blimey! Well, arrr, blow me down! Blimey! Finally, t' big J295 awakens with t' thunderous roar, and Shockwave is on its way! Blimey! T' rocket had a very straight accent considerin' the strong winds.

Recovery:
T' streamer deployed right on queue, arrr, shiver me timbers, and t' descent began. Ahoy! After fallin' for what seemed like an eternity, t' main chute deployed and Shockwave had a gentle touchdown about 1/2 mile away. Well, blow me down! Well, blow me down! Upon recovery, t' rocket had no damage except for a few scuffs on t' paint. Blimey! T' RRC2 be beepin' out 4,686ft. Blimey! Well, blow me down! A successful flight and Level 2 certification!

Summary:
This project sure has taught me a lot. Some will tell you that a certification flight should be as simple as possible, ya bilge rat, without electronics and with the smallest motor available for t' certification bein' sought. Avast, me proud beauty! While thar is merit t' that opinion, me hearties, I felt that I be up t' t' challenge. Ahoy! This flight was full o' firsts for me. My first experience with dual-deployment, altimeters, and CTI motors. Ahoy! Begad! I also achieved a new personal altitude record. Begad! I can't wait to fly it again on a calm day!

PROs:

  • Cool lookin' rocket
  • Can be flown single-stage deployment without t' payload section and altimeter
  • Built tough
  • Flies very stable

CONs:

  • I can't think o' any except cost

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