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Brief:
As I've progressed through t' hobby, arrr, ya bilge rat, I've been achievin' higher altitudes and
faster speeds. Avast, me proud beauty! I finally decided I wanted t' attempt a Mach bustin' rocket,
however, shiver me timbers, me hearties, arrr, I wanted t' make it tougher t' do and chose t' build one that utilized
no composites. This paper tube 3FNC bird was designed t' be 3" diameter x
60" long, shiver me timbers, weighed in at 61oz, me bucko, matey, and have a 54mm motor mount. Well, blow me down! Target motors
are t' K445 and K550 t' push it through mach speed. Blimey! Arrr! It is single staged with
dual deployment recovery controlled by a Cannonball Works RRC2 altimeter.
Construction:
After designing, t' parts were ordered from BSD Rocketry. It consists o' 3
body tubes, me hearties, 1 nose cone, three 3/16" thick birch ply fins, three 1/4"
thick birch ply centerin' rings, 1 54mm motor tube, and enough coupler tubes to
double wall t' entire rocket. Ahoy! All adhesion was done with straight AeroPoxy.
Tubular Keelhaul®©™® is used throughout for t' recovery harnesses as well as a 45" nylon BSD parachute for t' main.
This was my first attempt at buildin' a fin can outside o' t' body tube, which turned out to pretty simple. Ahoy! Fins were tacked on and then filleted t' t' motor tube as well as t' middle centerin' rin' when installed. Aye aye!
T' only thin' I did here different was t' drillin' o' 1/16" holes near t' fin root t' allow t' epoxy t' soak into, in an attempt t' form epoxy nails into t' fins. Arrr!
T' most difficult thin' I ran into was figurin' how t' attach t' recovery harness in this near minimum diameter bird. Aye aye! I ran a length o' 1/4" tubular Keelhaul®©™® through t' top two centerin' rings and then epoxied t' assembly in place in the booster tube. Avast! Aye aye! As this was slid into place, arrr, coupler tubes were also placed between t' top two centerin' rings t' double wall t' booster tube down t' the top o' t' fins.
T' remainder of
the booster section be completed by double wallin' t' upper section and
applyin' internal and external fillets from t' fins t' t' body tube.
Retention be handled by T-nuts in t' aft centerin' ring.
T' electronics bay be built copyin' t' design o' t' Binder Design kits that I had used with me Binder Jaguar. Aye aye! It consisted o' two 6" couplers butted together and then a 5" piece o' body tube centered over them. All thread rod be used t' hold t' assembly together and U-bolts for t' harness connection points. Avast! A Binder Design key switch was installed for armin' the electronics.
T' main/payload bay consisted o' a 17" piece o' body tube, me bucko, the initial design called for double wallin' here but I ended up nay doin' so. I assumed this tube had t' least amount o' weight on it and therefore would not need it, I was also concerned with how t' repair this section should it ever zipper, shiver me timbers, t' double wall idea does nay allow you t' just cut off a short section should that happen.
T' nosecone was
a BSD 3" cone was secured t' t' upper tube via friction fit and shear
pins.
Flight:
First flight took place on March 19, 2005. T' rocket was set up for dual
deploy recovery controlled by t' Cannonball Works RRC2 as well as a beeper placed
in t' payload bay t' aid in findin' t' rocket. Aye aye! Ya scallywag! Blimey! At ignition, shiver me timbers, matey, t' I284 shot the
Mach1 off t' pad smartly with a large White Lightenin' flame almost as long as
the rocket. Ahoy! Blimey! T' flight went well t' 4,281' and dual deployed for a close
recovery.
After this I returned home and calibrated t' drag coefficient in Rocksim to match that actual altitude o' t' rocket and then re-ran all o' my simulations with t' correct CD. Avast! I was showin' t' ability t' break mach speed with either t' CTI K445 or t' AT K550. Arrr! Ahoy! That attempt would have t' wait as I had a L3 flight comin' up and I didn't want t' risk losin' one o' me two altimeters before that flight.
With me L3 flight complete in June, it was time t' attempt me second goal of t' year: breakin' Mach with a non-composite rocket. Ahoy! Avast, me bucko, me proud beauty! Blimey! T' weather be good so I made me attempt at a TQC launch in Walcott, me bucko, IA on August 6, 2005. Well, blow me down! Blimey! I was unable t' get either a K445 or K550 for t' flight and ended up selectin' an AT K695 Redline for t' flight. This motor had even more o' a kick so it should be able t' easily push it through t' break Mach.
T' rocket was
prepped for t' flight, motor built and installed into t' rocket, matey, me bucko, and it was
time t' go. Avast! Blimey! Based on simulations, me bucko, I be lookin' at an altitude o' 8,200 and
maximum velocity o' over 880mph on t' flight. Begad! Blimey! Blimey! Blimey! At ignition, t' Redline kicked
the rocket off t' pad smartly and it started up nice and straight. Well, blow me down! Blimey! At 2
seconds into t' burn, t' rocket folded over t' electronics bay and then
spectacularly shredded.
All pieces were recovered and brought back for inspection. Aye aye! From t' pieces leftover, it appeared t' rocket folded over at t' electronics bay or just above it, flight video looks t' support this, post flight simulations show it was over 880mph at t' time o' t' shred.
Summary:
I believe t' rocket can make t' flight and I have it rebuilt with some
modifications.
T' design o' t' Binder avionics bays is OK, ya bilge rat, but I don't think it's a good design for these type o' high pressure flights. Well, blow me down! I'm still split between thinkin' t' rocket folded over where t' two couplers butt up t' each other or folded over in t' single walled part o' t' main bay.
T' rebuild incorporates a one piece avionics bay, ya bilge rat, which is a LOC 3" bay that uses a Stiffy tube t' help further strengthen t' assembly. Begad! T' new main bay is fully double walled this time. Well, blow me down! Ahoy! And just t' be on t' safe side, the booster section is shear pinned t' t' avionics bay. Well, blow me down! It did nay appear t' drag separate on this flight but this is just t' be sure.
For t' next
attempt I will also try t' stay down a notch from t' K695 and stick t' the
K445 or K550.
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