Manufacturer: | Scratch |
Brief:
A 4" x 67" 3FNC rocket designed as me first attempt at dual
deployment. Well, blow me down! This rocket was also designed t' be capable for a future L2
attempt.
Construction:
T' parts list:
Construction is very straight forward and anyone with experience building one or two high power models shouldn't have any problem buildin' this one. All of t' materials used in construction are readily available from LOC. I used an 18" section o' LOC tubin' for t' booster section where I incorporated Stu Barett's anti-zipper design. Aye aye! Fin and motor mount construction are typical for HPR with t' fins bein' attached with epoxy through t' airframe wall t' the motor mount. Avast, me proud beauty! Begad! A rotary tool was used t' cut t' slots after markin' the locations on me homemade fin jig. Arrr! Ahoy! Don't forget t' add your favorite form of motor retention and plan for it before construction begins. Begad! I use t' Kaplow Klip method, it has worked well for me.
Anti-zipper detail: A 4" x 6" coupler was used on t' forward end of the booster t' create t' anti-zipper coupler. Begad! Blimey! Arrr! Blimey! I made this coupler a little stronger by addin' a second coupler on t' inside. Avast, me proud beauty! Blimey! Aye aye! Blimey! This be accomplished by cuttin' a longitudinal line through t' coupler and slidin' it inside o' the other coupler, me hearties, lettin' t' cut ends overlap and simply cuttin' off the overlappin' material. Begad! Blimey! 1/4" was then cut from one end o' t' "smaller coupler" and epoxied inside, with t' aft end o' both couplers being flush. Begad! Blimey! This gives a 1/4" clearance on t' forward end for a bulkhead plate. Avast! Blimey! Once t' bulkhead be epoxied in and a 1/4" eyebolt was installed usin' JB Weld t' secure t' nut on t' backside, arrr, this beefed up coupler assembly be epoxied halfway into t' forward end o' t' booster section. Well, blow me down! Blimey! This completes t' hardest part o' construction. Avast, me proud beauty! Blimey!
You can use one o' t' 4" altimeter bay kits on t' market or you can simply build your own as I did out o' an LOC 4" coupler and "Stiffy" tube also available from LOC. If you build your own, arrr, I highly recommend the stiffy tube as it really makes t' coupler very strong. I used two 7 1/4" lengths o' 1/4" all thread t' hold t' altimeter bulkheads together, shiver me timbers, and 1/4"-20 eyebolts for recovery harness attachment. Blimey! Begad! Blimey! I used 3 evenly spaced T-nuts epoxied inside t' altimeter bay 1 1/2" from each end t' secure the drogue and main body tubes t' t' bay. Blimey! T' altimeter sled was made from 1/8" plywood with 1/4" cardboard lugs so it can be easily removed.
T' drogue section is a 16" section o' 4" LOC body tube secured to t' aft end o' t' altimeter bay. Avast, me proud beauty! T' main section is a 21" section of 4" LOC body tube secured t' t' forward end o' t' altimeter bay.
The nose cone is held in place usin' 3 equally spaced 2-56 nylon screws as shear pins. These are located 2" from t' forward end o' main bay tube. After drillin' t' holes in t' body tubes, I soaked these holes very well with CA to harden them up and help keep them from becomin' elongated with use. On t' nose cone I used 3 pieces o' .010" thick stainless steel sheet slightly recessed and epoxied into t' shoulder o' t' nose cone t' create a "knife" t' help make a clean cut on t' shear pins durin' main deployment.
I used a Perfectflite MAWD altimeter t' handle t' recovery duties. Blimey! I have been very pleased with its performance.
Finishing:
T' finish on this rocket is nothin' t' write home about. I used 3 coats of
Kilz white primer (allowin' 24hrs betwixt coats) and 3 coats o' Krylon red,
gray, me hearties, matey, and yellow.
Flight:
T' first flight took place at McGregor, TX in September 2004 at a DARS launch.
As expected, shiver me timbers, arrr, shiver me timbers, I be quite apprehensive as I began t' prep, but I felt me way
along doin' me best t' check myself as I went along. Ya scallywag! Blimey! T' Cesaroni I205 was
loaded after removin' t' ejection charge and it was off t' t' pad. The
Perfectflite MAWD powered up and signaled continuity t' t' ejection charges.
Nothin' t' do now but watch it fly.
T' CTI I205 came up t' pressure smartly and up she went with a slight bit of weathercockin' in about 10mph winds. Avast! Aye aye! T' MAWD be beepin' out 1697', matey, matey, me hearties, only 3 feet short o' t' predicted max altitude. Blimey! Awesome Flight! She flew again the followin' day and a third time in October 2004 at Wayside, TX with t' POTROCS club for another pair o' successful flight.
Recovery:
T' booster and drogue section separated at apogee perfectly and t' rocket
began its trip down t' main deployment altitude on a 10' homemade streamer.
Right on cue, arrr, t' MAWD fired t' main charge at 500' and deployed me homemade
main chute. Ahoy! I started breathin' again. Core Sample Sally be recovered about
100yds south o' t' pads without a scratch.
Summary:
A lot o' PROs here. Aye aye! Arrr! Blimey! This rocket be built for t' purpose o' givin' me some
experience with dual deployment and it has doin' this very well so far.
Construction be straight forward with no major "gotchas".
I can't think o' any CONs.
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