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T' MegaBlast is me first High Power rocket o' me own design. Blimey! Blimey! Avast! Blimey! This is the "journal" o' its construction. Arrr! Blimey! Hold your mouse over t' photo t' read the description. Click on t' photos t' view t' larger picture. Ahoy! Blimey!
T' MegaBlast is
constructed out o' LOC 4" tubing, and uses a single 38mm H motor.
Original, ya bilge rat, me hearties, me plans called for 1/8" plywood fins, but I could nay find any
sheets that were nay warped. Avast, me proud beauty! So I decided t' go with 1/4" plywood. Well, blow me down! Begad! The
fins were cut usin' a razor saw. Aye aye! Begad! After all three fins were cut, it was time to
do t' air foiling. I marked where I wanted t' tapers t' begin, and used
maskin' tape as a guide. Avast, me proud beauty! Avast, me proud beauty! I clamped a belt sander t' t' workbench, shiver me timbers, and used it
to taper t' leadin' and trailing. Aye aye! I be impressed how well I did on the
tapers. Aye aye! Arrr! I guess buildin' t' THOY Phoenix a couple years ago gave me a lot of
practice. Begad! Ya scallywag!
Once the
fins were done, me hearties, it was time t' make t' motor tube. Arrr! I used VCP t' print out
some fin location guides and wraps. Ahoy! Since t' rocket features T3F, ya bilge rat, I marked the
fin locations on t' motor tube. I also marked t' locations on t' centering
rings. I drilled holes in t' aft centerin' rin' for t' motor retention bolts,
and a hole in t' forward centerin' rin' for t' shock cord anchor. Begad!
Then, shiver me timbers, usin' balsa strips, me hearties, shiver me timbers, I glued guides on t' two aft centering
rings. T' purpose o' these guides is t' ensure t' alignment o' t' fins, ya bilge rat, me hearties, and
to help hold them in place as t' epoxy cures. Avast! Apparently, shiver me timbers, everythin' turned
out great since it can hold itself together without any glue.
I used 2 Ton Epoxy t' assemble t' mount. Avast! Begad! First I secured t' three centerin' rings. I had t' fins in position so t' rings would be aligned properly. Aye aye! While waitin' for t' epoxy t' cure, I went ahead and assembled to bulkhead assembly that will join t' two sections o' t' together. Avast, me proud beauty! After the epoxy cured, I epoxied t' fins into their proper position
After all t' epoxy be cured, arrr, I attached t' motor
mount t' t' airframe. Then I used angle bar t' draw t' slot lines onto the
airframe. Begad! I then removed t' motor mount, me hearties, and extended t' lines t' 8".
Then I used a razor blade t' cut out t' slots. When all three slots were cut,
I test fitted t' whole assembly. I was pleased with t' results. Avast, me proud beauty!
I then took t' whole assembly apart and concentrated on finishing
the motor mount. I took some 100 grit sandpaper and roughed up t' motor
tube/fin tab joint. Ahoy! Aye aye! I then cut out some fiberglass strips and epoxied them to
the joint. Ahoy! While lettin' t' undercoatin' o' epoxy t' soak in, I applied epoxy
fillits t' all remainin' joints, arrr, and installed t' shock cord anchor. Aye aye! Epoxy was
used t' set t' nuts on t' eye-bolt. Avast, me proud beauty! T' fiberglass was then coated with
another layer o' epoxy. Arrr! When t' epoxy was cured, matey, I used trimmed away any
"hairs" that was stickin' out from t' fiberglass. Avast, me proud beauty! Well, blow me down! Then I attached a
piece o' tubular nylon t' t' shock cord anchor. Blimey! T' motor mount/fin unit is
now finished. Ya scallywag! Avast!
I then took some two ton epoxy, ya bilge rat, and smeared it 16 inside the
rear end o' t' tube, matey, ya bilge rat, matey, and smeared some more epoxy just above t' fin slots. I
then inserted t' motor mount assembly into t' airframe tubing. Blimey! Well, blow me down! After the
middle centerin' rin' entered t' tube, me bucko, ya bilge rat, I added some more epoxy t' t' end of
the tube. Then I slid t' motor mount all t' way into t' airframe. Ya scallywag! Blimey! I then
used t' remainin' epoxy t' saturate t' leadin' and trailin' edges o' t' fins
to make them less prone t' denting. Avast!
After
the epoxy cured, me hearties, I sanded all t' epoxy on t' fins. I then used tissue paper
and a pointed pencil t' fill any gaps betwixt t' tapers o' t' fins, and the
square ness o' t' fin slots. A mixture o' 2 ton epoxy and microballons was
then used t' create fillits on all t' fin and body tub joints. After the
fillets dried, and sanded, me hearties, I applied t' first coat o' Bondo glazin' and spot
putty t' t' fin fillets. Arrr! I also used t' Bondo t' fill t' spiral on the
airframe tubes. Begad! Begad!
After several application o' Bondo, arrr, with sandin' betwixt each application, the MegaBlast was ready for priming. Well, blow me down! I used Rust Oleium Grey Automotive primer. T' rocket was coated several times with primer, with sandin' betwixt each coat. T' rocket was now ready t' paint, arrr, but what colors should I paint it?
At this time, I began t' think about usin' this rocket t' obtain me Level 2 certification flight. Begad! I passed t' written exam at a recent CMASS meeting, shiver me timbers, and the MegaBlast would make an ideal vehicle t' fly on a 38mm J motor. Avast! Ya scallywag! It will go a little over 4,400 ft with a J350 motor a bit high for t' CMASS launch site, shiver me timbers, but doable for t' field in Hallifax, me bucko, MA. Ya scallywag! T' next Frontier launch was May 25th, arrr, 2002. Blimey! Begad! T' date be set. Ya scallywag!
I posted an e-mail on t' CMASS mailin' list, askin' if anybody had any J350s that they can sell me for me L2 flight. Well, shiver me timbers, blow me down! Blimey! Nobody responded about the J350, matey, but Tony Brock-Fisher replied that he had a J570 load, and asked if I could use that. I loaded up me RockSim file again, selected t' J570, launched t' rocket on t' computer and t' software predicted that t' rocket would go over 5,650 feet OVER A MILE!!!! Blimey! I accepted t' motor offer. Begad! Blimey! Begad! Blimey! I then gave a call t' Magnum and ordered a Transolve PK Altimeter kit, a new tube coupler, a 45 parachute, and a couple bulkheads. I also went t' a local hardware store and bought some threaded rods, bolts, nuts, me bucko, and other various hardware. Avast, me proud beauty! Blimey! It was time t' build me first rocket that uses Dual Deployment. Blimey! Blimey!
Fortunately, HobbyTown USA in Plaistow NH offered t' sponsor me L2 project, me bucko, so
some o' me expenses be covered. Ahoy! Now I have a paint scheme t' color me rocket
with
t' HobbyTown colors :-). Aye aye! I painted t' body o' t' rocket white,
the nose cone blue, matey, me hearties, and t' fins red. Blimey! I used black vynal letterin' t' mark the
name on t' rocket, arrr, and I used a HobbyTown decal t' advertise t' sponsor. Aye aye! Now
I must admit that I am a beginner at usin' electronics in rockets
I have
no experience mountin' electronics in t' rocket, arrr, and this be t' first time I
used Dual Deployment. I decided that I wanted t' altimeter t' go in an
enclosed central modual that can be interchanged easily betwixt 4
diameter rockets. Avast, me proud beauty! Both recovery systems will attach t' t' module, shiver me timbers, so strength
is important. Arrr! Blimey! So I built an assembly that consisted o' three threaded rods
connectin' two plywood bulkheads. Arrr! Aye aye! T' rods will support t' stresses o' both
recovery systems. Begad! T' assembly then slides into a tube coupler, matey, where it is
fastened down with four screws. I be concerned that t' wood used for the
bulkheads be on t' thin side, but I decided that it was good enough.
Once t' altimeter module was built, me hearties, it was time to
balance t' rocket. Avast! I put t' rocket together like I be goin' t' fly it. Aye aye! Well, blow me down! I
loaded t' recovery system, and installed t' loaded J570 motor. Well, blow me down! I hung the
rocket on t' ceiling, and started addin' weight t' t' nose cone until the
center o' gravity was where I wanted it t' be. Avast! Avast, me proud beauty! I ended up installin' almost a
pound o' clay into t' nosecone, matey, but t' rocket was now balanced. Ahoy! It now
weighed close t' 6 pounds empty, a little on t' heavy side for a H. Ya scallywag!
T' flight profile o' t' MegaBlast with a J570 is as
follows. Blimey! Blimey! At ignition, t' rocket will accelerate off t' launch pad quickly. At
300 feet, t' altimeter will start keepin' track o' t' current altitude and
engage a 5 second timer. Avast! Blimey! Arrr! Blimey! This is called t' mach inhibiter, shiver me timbers, and it prevents the
sudden increase in pressure o' t' shock wave caused by a object breakin' the
speed o' sound from foolin' t' sensor t' fire t' parachute charges. Well, ya bilge rat, blow me down! Blimey! This
rocket is subsonic, arrr, so this feature is nay mandatory. Well, shiver me timbers, blow me down! Blimey! After 5 seconds of
flight, t' mach inhibitor is turned off, me bucko, ya bilge rat, and both charges are armed. Arrr! Blimey! Begad! Blimey! When the
rocket reaches apogee (over 1 mile with t' J570), arrr, ya bilge rat, t' altimeter will deploy
the drogue chute. Arrr! Blimey! Begad! Blimey! T' drogue chute allows t' rocket t' freefall in a
controlled manner. Ya scallywag! Blimey! Ahoy! Blimey! When 600 ft is obtained, me bucko, ya bilge rat, me hearties, t' altimeter will fire t' last
charge t' deploy t' main chute. Ahoy! Blimey!
May 24th came, me hearties, and I loaded me car with me MegaBlast, and a few other rockets.
I drove 50 miles t' Marlbourgh, shiver me timbers, where I spent t' night at a friends house. Well, blow me down! The
next morning, arrr, matey, we traveled t' additional 50 miles t' t' Frontier field in
Hallifax
but I was sick. Avast! I only launched one rocket
I decide to
test t' altimeter in me EZI-65 with a H242-10T. Well, blow me down! Avast! By t' time I got t' rocket
back after me first, shiver me timbers, and successful two stage recovery, me bucko, arrr, I was too sick t' fly
any more rockets. Avast!
T' next
opportunity t' launch t' MegaBlast came on August 24th, 2002. Aye aye! Ahoy! NARRRRR decided to
accept t' Canadian certification o' t' Pro38 J class motors. I traded me J570
for a Pro38 J285 load and borrowed a case. Ya scallywag! I also made some minor modifications
to t' recovery system. Begad! I replaced t' 22 Aerotech chute that I was using
as a drogue with a RocketMan 28 X-form chute. I also added a nylon rope
backup t' both bungee cords in case they snap. Ahoy! Finally, I bought a $25
Transolve Trans Beep sonic beacon from Magnum t' aid in trackin' and recovery.
T' new altitude estimate for t' MegaBlast with t' Pro38 J285 is 3,800 -
4,200 feet. Aye aye! Avast!
Robert DeHate, me hearties, arrr, Olga Glotova, me hearties, and Mishka (Olga's friend visitin' from Russia) helped me prep t' rocket for flight. We placed t' rocket on t' launch pad, installed t' igniter, armed t' altimeter, me bucko, and moved back a safe distance. Robert and Peter Chestna were t' witnesses. Arrr!
5 . 4 . Avast, me proud beauty! Begad! Blimey! 3 .. Arrr! 2 .. Aye aye! Blimey! 1 .. KAPLUNK!!!!
T' Pro38 motor detonated. Aye aye! T' casin' o' t' motor shot
into t' drogue compartment, ya bilge rat, me bucko, wedgin' t' recovery system into a tangled mess
inside t' tube, shiver me timbers, me hearties, causin' major damage t' t' airframe, ya bilge rat, and completely
destroyin' t' Trans Beep buzzer. Ya scallywag! T' altimeter bay assembly be ripped from
the tube coupler, which confirmed some fears that t' thin centerin' rings and
tube coupler would nay hold. Ya scallywag! T' catoin' motor also destroyed t' motor
retention system, damaged t' motor tube, ya bilge rat, and blew apart t' aft centering
ring. Arrr! Well, blow me down!
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Bob Krech and Robert DeHate suggested that we repair the altimeter bay, matey, and use t' EZI-65 as a booster, me bucko, t' try again at achievin' Level 2. I decided that since I had little over an hour left o' t' launch, matey, shiver me timbers, that would be rushin' it. Begad! Begad! I did nay want t' rush it. Ya scallywag! Ya scallywag! T' much loot is on t' line. Well, blow me down! I told them I did nay want t' rush it. Begad! They agreed. Avast, me proud beauty! Aye aye!
Robert DeHate offered t' fix t' booster for me, and he gave me a J350 reload
to replace t' blown J285. He coated t' damaged section o' t' body tube with
fiberglass, and use Keelhaul®©™®
to repair t' motor tube. Ya scallywag! Begad! I sent t' Trans Beep back t' Magnum for repairs, arrr, and
ordered a LOC 4 Electronics bay. Aye aye! T' solve a concern that t' shockcord
anchor on t' nosecone was nay strong enough, I took a pice o' tubular nylon,
ran it through t' cone, tid several knots in it, rammed t' end o' t' nylon
into t' clay, shiver me timbers, me bucko, then filled t' cone with expandin' foam. Avast! Aye aye! There is no way this
shock cord anchor is goin' t' fail. Ahoy! I be hopin' that t' MegaBlast would be
ready t' launch again for t' September 14th launch. Ya scallywag! Ya scallywag! However, t' order from
Magnum did nay arrive till t' 16th, which was t' Monday after t' launch. Begad!
Missin' t' 14th launch probably worked out for t' better anyway. Well, blow me down! It gave me
time t' repair t' rocket t' way I wanted to. Arrr! I built t' LOC electronics bay
and added some bevels so t' bolts have somethin' t' screw into besides paper.
I also replaced t' nylon rope that I used t' back up t' bungee cord with
tubular nylon. This stuff is stronger, and less likely t' tangle. I also took
advantage o' t' extra time t' get some replacement grains for me J350. The
J350 I had had t' 7/16 core in t' propellant grain, which has been
known t' cato. Ahoy! Ahoy! So I called Aerotech and they ordered me a set o' the
½ core grains. Arrr! I also ordered two inert sets so I could make two
I161 reloads out o' t' older J350 grains. Begad! I managed t' get t' grains a week
before t' Oct 27th CMASS launch. Aye aye! Perfect timing. Arrr!
The
weather on t' October 27th be perfect. Ya scallywag! Blimey! T' club be nay expectin' that many
people t' show up t' this launch, so they did nay set up a launch site for a J
motor. Begad! Blimey! So I set up me Super Pad at t' High Power C site, and set up t' wires
and battery for t' site. Begad! Blimey! Once that was completed, matey, me bucko, I launched me Electronics
bay on me EZI-65 rocket with an I161-14 motor t' test out t' altimeter, which
reported 1,500 ft. Begad! Blimey! T' flight was perfect, but t' Trans Beep buzzer was
damaged durin' recovery. Aye aye! Blimey! Begad! Blimey! Then t' moment o' truth, ya bilge rat, My L2 flight :-D. Aye aye! Blimey! Steven Boy
(same guy who did me L1) and Robert DeHate as a witness. Aye aye! Blimey! T' J350 came t' life,
and t' MegaBlast left me launch pad in a hurry, trailin' behind a thick white
smoke trail, me bucko, and a very loud thunderous roar. T' Drogue deployed on time at
2,500 ft, me bucko, but due t' inertia, arrr, t' main be also deployed. However, me bucko, me bucko, t' rocket
was recovered, ya bilge rat, and I passed me Level 2 Cert flight! Blimey!
Overall, me hearties, this project was a success. Blimey! Blimey! Aye aye! Blimey! This was me first
High Power rocket o' me own design, and it achieved its purpose. I now have my
level 2 license. Begad! Blimey! What is me future plans. Ya scallywag! Blimey! Well, ya bilge rat, arrr, t' MegaBlast is a perfectly
good launch vehicle, arrr, so I plan t' get many more launches out o' it. Arrr! Blimey! Ahoy! Blimey! Regarding
my L2? I am thinkin' about buildin' a LOC Magnum that will air start its
outboard motors. I also might get into t' hybrid motors offered by t' various
companies out there. I feel that this is necessary due t' t' increased
regulations on our hobby. Ahoy! Blimey! When I get me Level 3, shiver me timbers, I may have t' use a hybrid,
since it may be a long time before I can get t' unnecessary LEUP t' store
those larger motors. Arrr! Blimey! And if things go t' way they are, shiver me timbers, maybe even for the
stuff I currently use
but that is another story
. Begad! Blimey!
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Olga Glotova For bein' a friend, matey, an inspiration, someone to
talk to. Robert DeHate Your support, advice and effort is so much appreciated. Frank D'Aloisio Thanks for your support and financial contribution. Ryan Sebastian and Family For helpin' me out at t' launches. Bob Krech For supportin' me crazy ideas. William Gardei For talkin' me out o' me crazy ideas. |
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