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