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. Ya scallywag! It is 4" in diameter, shiver me timbers, 90" long, weighs 153oz loaded without motor, shiver me timbers, and has a 54mm motor mount.

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

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

T' altimeter bay was fabricated from a standard 7" long PML coupler, two PML bulkheads, me bucko, ya bilge rat, 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 be affixed t' the drogue end o' t' bay. Blimey! This would serve t' tie t' entire bay together and provide a mount for t' RRC2 altimeter. Begad! Well, shiver me timbers, blow me down! 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. Well, blow me down! 3/4" PVC endcaps were mounted on each end o' t' bay t' contain the ejection charges. Avast!

(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. Aye aye! Aye aye! Three equally spaced 1/8" static ports were also drilled. T' finish t' bay, a thin skin o' 30-minute epoxy be poured in t' drogue side o' t' bay with t' cap installed. Begad! This step totally seals the drogue side o' t' bay, ya bilge rat, and retains t' endcap. Begad! A mount for t' RRC2 altimeter was made by epoxyin' a copper tube t' a piece o' G-10 fiberglass. Avast, me proud beauty! Blimey! 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. Well, blow me down! Avast, shiver me timbers, me proud beauty! 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, matey, 2004. I arrived at t' launch and rounded up a few friends t' be my certification team. Ya scallywag! After acein' t' written L2 test, 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. Drogue and main harnesses are both 25ft in length. After t' recovery system was buttoned up, I turned attention t' loadin' t' motor. This flight would be on a CTI 3-grain Pro54 motor. Begad! Once t' motor be loaded and installed, we took a few pictures and headed t' t' pad. Blimey! Ya scallywag! T' day turned out t' be a real bummer weather-wise, with strong 20MPH winds. Avast! With t' help o' me test proctor and a friend, ya bilge rat, Shockwave was put on t' pad, and t' igniter installed. Ahoy! I armed the electronics, verified t' RRC2 was beepin' right, and headed back t' LCO table. Aye aye!

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

Recovery:
T' streamer deployed right on queue, arrr, 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. Upon recovery, shiver me timbers, t' rocket had no damage except for a few scuffs on t' paint. Well, blow me down! T' RRC2 was beepin' out 4,686ft. A successful flight and Level 2 certification!

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