(Contributed - by Bill Eichelberger
- 02/09/06)
Brief:
This project was started with the intent of putting the legendary Centuri
Taurus more in line with the way I had imagined/remembered it back in the late
'70s. While cloning the Taurus recently, one thing I was surprised about was
the rocket's size relative to the Centuri Super Kits.
In short, I had expected the Taurus to be quite a bit bigger than it
actually was, but the size of the components and the subsequent dry-fit told
the real story. With this project I set out to change all that. Using parts
from BMS, Red Arrow Hobbies, FlisKits, and Thrustline, I scaled up the Taurus
up so that it could claim it's rightful place as one of the Super Kits. (In my
mind at least, and when you get down to it, what else matters?)
Construction:
The parts list:
- BNC-70AJ nose cone (BMS)
- 2 TA-6070 transitions (BMS)
- 3 BNC-20B pod cones (BMS)
- 3.7" T-70 upper body tube (BMS)
- 9.5" BT-60 center body tube (Red Arrow)
- 13.2" T-70 lower body tube (BMS)
- 3 6.6" BT-20 pod tubes (Red Arrow)
- 3 x 18mm cluster motor mount for BT-70 (Thrustline)
- 36" length Kevlar®
shock cord
- 36" length 1/8" sewing elastic shock cord
- BT-60 sized ejection baffle (FlisKits)
- 1/8" balsa fin stock
- Medium screw eye
- Large snap swivel
- 18" nylon parachute (Thrustline)
- decal
Construction began when the BT-70 tube, transitions and cones arrived from
BMS. I immediately started to work hollowing out the transitions with my Dremel
tool. I managed to get two fairly decent looking holes with the Dremel while at
the same time stirring up enough balsa dust to make the front steps looked like
they'd been hit by a sudden snowstorm of talcum powder. When the hollowing was
finished, I dry fit the collected parts together. The result was pretty much
what I had hoped for: a Taurus sized along the Super Kits.
At this point I assembled the Thrustline 3 x 18mm cluster engine mount. The
holes on this mount are laser cut and the tubes slip in without any trouble
whatsoever. The fit is firm, and the best part is that there are no holes to
stuff with the messy glue and recovery wadding mixture that I've used on my
other clusters. Another advantage is the unit's great looks, which are almost
too good to consider covering up with a body tube. The Thrustline kit comes
with two laser cut centering rings, three motor tubes, three engine blocks,
three engine hooks, and a length of Kevlar®.
I used everything except for the engine hooks, which I put aside for use on
future vintage projects, and the Kevlar®,
because I was also incorporating a baffle from FlisKits.


The FlisKits baffle is sized for a BT-60, so I planned to fit it into the
center section of the rocket. The recovery system was completed with a 36"
length of 1/8" sewing elastic and a medium sized screw eye, which was
epoxied into the nose cone. The 18" nylon chute, also a Thrustline
product, was attached using a large snap swivel.
I attached the fins to the bottom tube, dry fit the pieces together, and
sprayed the whole structure with a coat of Valspar primer to toughen it for the
sanding and sealing to come. Sealing was done using several coats of thinned
Elmer's Fill 'n' Finish and the rocket was sanded after each coat.
The fins and pod supports were cut from a sheet of hard 1/8" balsa and
attached using gel CA, then given a double fillet treatment with Elmer's wood
glue. After this I sprayed the whole rocket with another coat of Valspar
primer, then several coats of Valspar gloss white. (Because of the trouble I
had masking my 1:1 clone I decided to wait until after the painting was
finished to mount the finished pods onto the supports.)
With the white base coat in place, I masked off the appropriate areas on
the bottom section using good quality masking tape, then sprayed the remainder
of the section with Valspar Gloss Black. The center BT-60 section, including
one of the TA-6070 transitions, was sprayed with Valspar Silver Metallic, while
the other TA-6070 was sprayed Gloss Black. This left only the nose and pod
cones, all of which were sprayed with Valspar Harvest Orange. After the masks
were removed from the bottom section I prepared to begin final assembly.
Then the whole project went into the toilet.
While walking through my room in the basement after retrieving a can of paint
for some touch-up on the project, I noticed my Taurus clone sitting on the old
Hoosier cabinet. As my foot touched the first step on the way upstairs, a
horrible realization hit me like a club. The original Centuri Taurus had been
built with a combination of ST-8 and ST-13 body tubes, but somehow I had
figured all of the numbers for my upscale out using the Estes BT-60 to BT-70
size difference as a starting point for figuring out the tube lengths involved
in the upscale. Worse yet, I had also sized the fins using this number. What
made this so disastrous was that the Taurus was originally built using the
ST-13 (Estes BT-56) instead of the BT-60. This meant that instead of a 1.36x
upscale, I should have been building a 1.65x upscale. My tubes and fins were
all too small.
Luckily my house was only two stories high so jumping wasn't an option
(although retaking math obviously should have been at some point.) As you might
imagine, this set me back a bit, and I considered just adding on to the
existing pieces, but in the end I decided to cut all new BT-70 parts from the
section of tube I had remaining. I added a piece to the existing BT-60 center
section, mostly because I had already installed the FlisKits baffle and glued
the topmost transition to the tube. It was easier and quite a bit less heart
wrenching to just add the small piece of BT-60 and do a reseal/resand. I set
the original bottom section aside with the intention of buying another TA-6070
transition and making a Taurus-inspired "supply ship" out of it. I
was able to squeeze out new upper and lower BT-70 sections from the piece of
BT-70 I had left over. (I checked these measurements three times. I hadn't paid
such close attention to measurements since Miss February of 1968 and I didn't
understand them either.)
Flight:
After waiting for what seemed like an eternity, I finally found myself with a
slim weather window to get the big Taurus flying. Conditions were far from
optimal with a cold 10+ mph wind strafing the VOA field, but as long as I
wasn't the only one to show up for the Quark launch that day, I was flying.
For the inaugural flight of the day, I decided to err (if I were to err) on the
side of caution and chose a trio of B6-4s. Though it was planned as my first
flight that day, a little blind spot of mine involving launch lugs kept it from
its leadoff spot in my launching order. When the time came to launch I double
checked everything before heading out to the pad with my .
When the time came to launch, I had another club member push the button so
that I could get a picture of the liftoff. (In case it was the only chance I
ever got. A possibility considering how unlucky it had been up to this point.)
The liftoff was slow on the three B6-4s and every bit as cool as I had hoped it
would be with plenty of smoke and flame. It tipped into the wind off the pad,
and I was surprised at the height it attained. Ejection occurred quite early
and for a second the big Taurus looked like it had been jerked from a
Vaudeville stage by a cartoon hook. The large Thrustline nylon chute unfurled
and it rode the breeze out into the vegetation...and toward the access road.
For a moment I thought that the bad luck streak was going to continue, but it
took a fortuitous turn away from the road and landed well back in the weeds.
Weeds I could deal with. Roads I couldn't.
Flight two was the 3 x C6-5 flight I had planned from the start. The Taurus
left the pad noticeably quicker and topped out quite a bit higher than on the
three Bs. This flight went due west into the breeze as it accelerated off the
pad, arcing toward a large grove of trees but never appearing to be threatened
by them. The ejection charges were closer to true this time as they fired just
as the rocket tipped over. It rode the breeze back, still quite high as it
passed over the flightline. The recovery walk was a long one, and I found it
stuck in a tree. Luckily it was a waist high tree.
The third flight came at NARAM 47. Flying on a 3 x C6-5 load alongside the
Semroc SLS Laser X prototype, the flight itself was beautiful. The recovery was
a different story. While the cameras rolled, the big Taurus popped the chutes
right on the money after a textbook flight. Then came the drama. From my spot
near the LCO tent I could see that the landing would be close in respect to the
access road. (By close, I mean that I could see that it was going to land dead
center on the access road.) The jarring impact splitered one fin, loosened
another, broke off two pods, and partially crushed the upper section of BT-70.
(The SLS Laser X wound up with a comparitively soft landing on the field and
was spared any damage.) I've since tried to make the repairs, but the damage is
extensive enough that it will always be noticeable. It kind of takes the wind
out of my sails, so as of today, it remains in a heap in my shop. Maybe
someday.
Summary:
PROs: Overall bulk. The Taurus lines upscale well. Cool cluster performance.
CONs: The apparent curse that has been cast on the project.