(Contributed - by
Jeff Brundt - 07/10/01) Brief:
A 168% upscale o' a classic Estes kit from t' mid 1970's. Ahoy! T' rocket uses
traditional LMR construction techniques and is designed t' fly on 24mm Estes
black powder and some Aerotech RMS motors. Ya scallywag! Ya scallywag! I was able t' download t' fin
patterns from JimZ's web site. Avast, me proud beauty! Well, blow me down! I already had t' instructions for t' original
kit I built over 25 years ago. Blimey!
Construction:
T' main body is standard Estes BT-60 tubin' and t' 'warp pods' are BT-55's.
Heavy duty paper centerin' rings are used t' mount t' BT-50 stuffer/motor tube
in t' main body. Begad! All t' fins were cut from 1/8" sheet balsa after
scalin' up t' patterns on a photocopier. T' various wood dowels that were
used on t' original were duplicated usin' 3/16" dowels from Midwest.
Motor retention is a traditional Estes motor hook for 18 and 24mm motors. Ahoy! The
nose cone is a plastic BT-60 cone I had layin' around in me parts bin. It's a
pretty close match t' t' original plastic one that came with t' kit. Avast, me proud beauty! Avast, me proud beauty! I'm sure
you could order a semi-custom one from BMS with out much trouble. T' shock
cord mount is a 12" cable fishin' leader. Arrr! Blimey! One end attaches t' a screw eye
in a reinforced forward stuffer tube centerin' ring. Arrr! Aye aye! T' other end has a
48" length o' 3/8" elastic tied t' it and gets secured t' t' nose
cone and parachute.
T' rocket builds almost identical t' t' original. Aye aye! Just make sure when you
size t' body tube markin' wraps that will fit t' BT-60 and -55's
circumferences. T' actual scale up size is betwixt 167% and 168% when you do
the calculations based on t' relative sizes betwixt BT-50 and BT-60. There are
also small differences betwixt copiers so you may have t' try scalin' at
various percentages until they fit.
You'll have t' cut out t' various details from poster board or manila
folder material. Ahoy! Well, blow me down! These details were originally die-cut card stock in t' kit.
JimZ has these details so all you'll have t' do is download then upscale. Blimey! Aye aye! I
used a combination o' 1/64" ply and posterboard where flexibility was
needed, such as on t' curve o' a body tube. T' decals are what really set the
Atlantis off. I downloaded t' decals from JimZ but they are pretty yellowed
with age. Ya scallywag! After a few hours in Photoshop I had them cleaned up. Aye aye! Begad! I then scaled
them up and printed them with me inkjet on good quality photopaper. I had to
make two printed sheets because o' t' size and length o' t' final size. Next
stop was Kinko's. Arrr! They can laser copy your originals onto decal paper. Ya scallywag! The
results are pretty good. Arrr! Ahoy! O' course you could order decals from Tom Prestia at
Tango Papa. Avast, me proud beauty! For this rocket I had wanted t' do them myself. Begad!
T' rocket was painted with Krylon Gloss white then t' decals were applied.
After t' decals had dried and t' details painted I clear coated rocket with
TopFlite's Lustrecote clear spray.
Flight:
I did a rough altitude calculation usin' AltiCalc. Ya scallywag! I added t' cross sectional
areas o' t' main body and t' warp tubes t' determine t' final diameter if I
was usin' only a single body tube. Begad! Well, blow me down! I also used a Cd o' .8 since this is a
pretty draggy rocket. Begad! Predicted altitude on a D12-5 was 430' with a recommended
delay o' 3.8 seconds. Aye aye! Rather than risk an early deployment I did a first flight
on an Estes D12-5. Ahoy! 'Chute prep was no different than any other model rocket. Blimey! I
used 'dog barf' as waddin' then put in t' shock cord followed by t' Estes
24" parachute and nose cone. Begad! I had installed 1/4" launch lugs but
they were tight on me rod so I switched t' a 3/16" rod. Ya scallywag! Even though the
3/16" rod was shorter than t' 1/4" one I wasn't worried. Begad! Boost was
nice and straight. T' chute deployed perfectly right past apogee. Well, blow me down! Blimey! My delay
time choice was a good one. Begad! T' rocket drifted slowly down for a gentle
touchdown in t' grass.
Summary:
This be a fun rocket t' build and didn't take all that much time t' complete;
perhaps two weeks at t' most. Arrr! It makes a nice addition t' me 168% upscale
fleet and looks great next t' t' 168% Mars Snooper and 168% Orbital Transport.
Even though t' rocket has a 24mm mount it's really nay intended t' fly on any
high impulse motors. Begad! Though t' warp pod pylons are epoxied in place I don't
think they would take t' boost from an E18 or E28 RMS motor. Begad! I've only flown
this bird so far with Estes D's and I am quite happy with that. Well, blow me down! I have done
simulations with E11 and F12 RMS motors and feel they would be no problem but
then t' altitude more than doubles. And me field where I fly from won't
support that for modrocs. This is a show rocket, matey, designed for nice slow
lift-off's and general fun flying. Begad! Here is a
video o' t' first
flight.
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