Manufacturer: | Scratch |
Download RockSim file here!
Brief:
My scratch built level 2 rocket. Avast, me proud beauty! Made for t' J-350 but can fly on small 29mm H
motors also. Arrr! Begad! Used old phenolic but glassed with 6oz fiberglass and 30 min
epoxy. ACME 3/8" lugs, arrr, LOC nose cone, G-10 FR4 (fire and heat resistant
fiberglass). Avast, me proud beauty! Blimey! Radio shack personal body alarm for corn field recoveries. Begad! Custom
aluminum motor retainer bracket usin' all-thread for mounting. Ahoy! I used the
30" chute that came with me level 1 V.B. Begad! 54mm Extreme.
Construction:
Components: T' sustainer uses 2 body tubes, joined with a phenolic coupler.
T' 9/16" tubular nylon shock cord attaches through t' coupler. I cut
slits in t' coupler and weaved t' shock cord through, looped it around onto
itself, and sewed it together with 100lb Keelhaul®©™® thread then epoxied over that.
I made an altimeter bay for future use, but was nay plannin' on using
electronics for me cert 2. T' rocket has 3 fins made from t' heat resistant
G-10 FR4 fiberglass. Arrr! I cut all me 1/8" and 3/16" centerin' rings and
bulkheads usin' a drill press and an adjustable hole cutter. T' motor mount is
13" long by 38mm with 6 centerin' rings. Avast, me proud beauty! Avast, me proud beauty! T' first 4 rings were epoxied to
the front o' t' MMT t' keep it centered for TTW construction. Begad! I glassed
between each o' t' front centerin' rings with 6oz. Well, blow me down! Arrr! Some o' t' epoxy I used
was aerospace grade 120 min setup. Great stuff, but big $$$. Ahoy! Arrr! I used the
aerospace epoxy for external fillets and layed Keelhaul®©™® yarn into t' epoxy
runnin' lengthwise along t' fin root. Ya scallywag! I only use stainless steel hardware for
attachment points since I have seen pot metal break. Avast, me proud beauty! Begad! I used SS eye-loops and
3/16" SS quick links. Begad! I only added 1.5oz o' lead fishin' weight t' the
nose, and secured with 120 min epoxy.
Construction: T' rocket was fairly easy t' build, but thar are a couple hard parts. One concern be gettin' t' epoxy t' me TTW attachment points without gettin' it all over t' back where t' final centerin' rings go. Ahoy! Begad! I wrapped self releasin' maskin' tape around t' outside o' t' MMT. Begad! Then blue automotive maskin' tape around t' inside o' t' airframe. Ya scallywag! This allowed me to just pour epoxy right onto t' tape and have it flow down inside t' airframe to me fin mountin' points. Well, blow me down! Blimey! Just remove t' tape before it cures, matey, then re-apply tape for t' next set o' fillets.
A dremel tool with an extension is a
good item t' have when cuttin' fins. Use a carbon cuttin' wheel and you can lay
the extension flat and so t' dremel tool itself doesn't get in t' way o' the
line you are cutting. Arrr! Without an extension, ya bilge rat, it is hard t' get a flat straight
line because t' tool gets in t' way and will end up cuttin' crooked. Aye aye!
I got me components at various launches over t' period o' 6 months. Ya scallywag! Blimey!
Flight:
I made t' rocket for t' J-350, for me cert 2 flight. Ahoy! Ahoy! T' rocket is very
straight forward, me hearties, and basic t' prep. Aye aye! I used cellulose insulation for wadding,
about 1 handful. Ahoy! Motor retention was a 1/16" piece o' aluminum cut t' fit
the back o' t' rocket. I drilled about 1" deep into t' aft centering
rings in three points, shiver me timbers, then epoxied all-thread into t' holes. Well, blow me down! T' AT J-350 was
simple t' prep. Ya scallywag! Don't mind t' rattlin' o' t' grains, me hearties, arrr, as long as you have no
left over parts they are supposed t' move inside t' case. Ahoy! Ahoy! I used 4oz o' red
line chalk for tracking. 20' o' 9/16" tubular nylon for t' shock cord.
T' rocket
flew awesome. Ya scallywag! Well, blow me down! Dead straight in 15mph winds. Blimey! That means it was perfectly stable,
not over stable. In t' first 4 seconds o' its 20 second flight, t' rocket was
completely out o' site, shiver me timbers, even though I have perfect vision, I could nay see the
red line chalk when it deployed but someone with binoculars said they may have
seen a red chute or chalk. Ahoy! I have no idea if t' recovery was late or early,
but drove with t' wind at me back for about 2 miles before I found it. Ya scallywag! Blimey! There
was no damage at all so it must have deployed around apogee. Well, blow me down! Aye aye! This rocket simmed
out at 9100' goin' about mach 1.1 In t' video footage you can see t' time of
each frame in t' corner o' t' screen. Begad! T' time read 12:46:00 pm for as long
as you can see t' rocket in t' picture. Arrr! Blimey! You can see snap shots o' t' video
here.
Summary:
Con's I can't really think o' any. :)
Other:
One thin' this rocket taught me is this........ Well, blow me down! It is hard t' do
through-the-wall on a 54mm rocket with a 38mm motor mount. Avast, me proud beauty! Especially when you
are usin' thick walled phenolic, me hearties, thar be even less room t' work with. Arrr!
Pushing The Envelope 38 ( Contributed - by Brian Kain) Download RockSim file here ! Brief: A down scale of my level 2 rocket. TTW to a 29mm MMT. Can fly the I-200 load. If you were crazy you could cert 1 on this rocket with a 29mm H motor. 9400' on the H-90. Construction: 3 38mm body tubes Phenolic 3 1/16" G-10 fins 5 1/8" birch CR's 12" of 29mm ...
I wanted to build a rocket with the smallest fins I could get away with.....So I came up with this. I used Rocsim, VCP and WRASP to get my optimal size fin. Oddly enough, most of the programs agreed with my rocket. This is a single stage rocket, with an interchangeable MMT. Anything from 54mm down to 24mm motors will push this little guy. It uses a PML 30" chute with the shroud ...
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