(Contributed - by Chan Stevens - 10/13/08)
Not being much of a rocketry historian, I was a bit confused when I heard that Semroc was releasing the Mark. After
all, I already had stashed away a numbered Mark II kit, as well as a Mark II offered in 2007 at . Looking over
the JimZ archives, I could see
very little difference between the Estes Mark and the Estes Mark II.
After a bit of research, I learned that the Semroc Mark II is really a replica of the Carlisle Rock-a-Chute Mark
II, which featured one of the ugliest nose cones I've ever seen (fashioned from a crayon sharpener). The Semroc Mark
(plain) is modeled after the Estes K-2 design (which in turn was based upon the Carlisle Mark II). It was Estes' second
design, which followed on the heels of the Scout, intended to demonstrated additional recovery methods.
This small, lightweight rocket flies to eye-straining (or even vanishing) altitudes and uses streamer recovery.
This is considered an xKit, meaning it's marketed as a bag of parts without instructions, though instructions are
available at the JimZ archive site. Semroc had previously had a couple befuddled customers of their bag-o-parts kits
who did not have the savvy to navigate online to find the archives, and as a precaution Semroc will only sell xKits
direct to online customers.
Your $6.50 retail buys the following parts:
The instructions as noted are not supplied, so construction follows the instructions from the original kit, preserved
from 1961 on Jim Z's archive site.
- Balsa nose cone
- BT-30 body tube
- Balsa engine block
- Laser-cut balsa fins
- Crepe paper streamer
- Rubber shock cord
- 1/8" lug
Construction on this is pretty simple, as it's just a basic 3-fin/nose cone style
rocket, and by upgrading to laser-cut fins, Semroc has eliminated the hand cutting from the original.
This is a minimum diameter model, so there is no motor tube assembly. Instead, you simply glue a thrust ring into
the body tube. In sticking with the 1961 design, Semroc provides a balsa block that's been bored out (roughly 1/2"
long) instead of the more modern (and cheaper) 20/5 centering ring approach. There's certainly nothing with this, but I
was curious what that part was for, and needed to confirm its use by checking the instructions. Other than that one
step, I did not actually need the instructions for this.
I did deviate from the plan slightly, by ditching the rubber shock cord and tri-fold mount in favor of Kevlar
line looped around that balsa block, attached to 15" of elastic as it clears the body tube. I know the rubber is
sticking with the original design, but I've had less than stellar success with rubber and so think the upgrade is well
worth the effort.
The fins were attached using a bead of medium CA followed up with white glue fillets.
Nose cone attachment is via screw eye in the . The crepe paper streamer is held on via an adhesive band
cut onto label paper.
The cover art from 1961 shows a pretty complex paint pattern, especially considering this doesn't come with any
decals--checkerboard black/white pattern on the fins, and vertical stripes. The Semroc cover art looked a little nicer
and easier, so I tried to follow their lead a bit. I started with a gray primer base, then followed by painting the
body tube and fins a dark red metallic. The nose cone was painted with a gold metallic left over from my Sky of Gold
The Semroc cover art also included a neat looking set of black trim stripes--one vertical stripe with horizontal
bands at each end. Having just masked and painted a couple Saturn 1b's, I felt up to the challenge and so cut some
rectangular bands of tape about 2-3/8" long, then drew a vertical line up the body tube (from forward fin joint)
using a short piece of angle. That line would represent my centerline for the vertical black band. I then applied the
2-3/8" strips of tape about 3/8" short of each end of the line, with the gap (2-3/8" is too short to
make it around the body tube) centered over the line. I then masked off horizontal bands for the other end of the
3/8" top/bottom bands, and shot the exposed areas with Rustoleum
The finished effect doesn't look quite as nice as the Semroc cover art, but I was fairly pleased. I'd like to have
gone a lighter red, but the metallic is a nice effect.
½ out of 5
Recommended motors are all long delay 18mm's of A8-5, B6-6, C6-7. I grabbed an A8-3 from an open Blast Off Flight
Pack I'd picked up for half price. It absolutely boogied off the pad and even on an A8 was a strain to track to apogee.
The delay was very clearly too early and even a -5 would be slightly before apogee. I suspect I could also track this
on a B, but unless you're feeling lucky avoid using C's unless using some tracking powder as truely out of sight
flights would be in order.
The tiny (8") crepe paper streamer is mainly decorative/complying with safety code and does not really affect
the descent rate. The model is small and light enough not to care. Despite upgrading to Kevlar/elastc
shock cord, I still managed to suffer a smiley dent in the nose cone. Guess I should have gone with even more elastic.
out of 5
While there's nothing all that striking about this design (other than the fact it's less ugly than the Mark II), it
is a nice simple construction, uses quality components and there's clearly a nostalgic retro aspect to it. It flies
great. The only cons I'd offer are related to the adherence to the original design--rubber shock cord/tri-fold mount
and a decal for stripe to match the cover art would be sweet (though certainly add a buck or two to the cost).
out of 5
(Contributed - by John Thompson - 10/16/08)
I received this kit from Semroc at 50. Semroc gave the Mark to anyone who purchased a kit from them. The Mark
is a reproduction of the Estes kit #K-02 and is part of the Semroc XKits line. The XKits line of rockets are
beautifully recreated reproductions of classic Estes, FSI, and Centuri rockets we remember as kids.
The Mark is a simple, super light 3FNC rocket that will really get some altitude on A and B engines, and
will fly out-of-sight on C impulse engines. I wouldn't recommend flying this on a C engine as it may become a
The kit comes with a beautifully turned balsa nosecone, three laser-cut fins, a balsa engine block, a sturdy body
tube, crepe paper streamer, a screw eye, and a rubber shock cord.
- BT-30B Body Tube 6.125" Long
- BNC-30E Balsa Nose Cone
- EB-30 Balsa Engine Block
- FES-K2 Laser-Cut Balsa Fins
- LL-2B Launch Lug
- SC-1A Shock Cord 9"
- SM-1A Streamer 1" x 8"
- TD-1 Tape Disc
Construction directions are not included with the kit. The directions are to be downloaded from JimZ's website.
The kit does come with an "instruction manual" that gives a complete history of the rocket. In this
"instruction manual", Semroc acknowledges that the streamer is a little short, but is the same length as the
original. I have to agree with that assessment and I should also mention that the shock cord is a little too short as
Because the instructions were scans of the original Estes instructions, the build was smooth and error free.
There were no "gotchas" or alignment issues, and all the parts fit together perfectly.
The only special tool you will need is an empty engine casing to push the engine block to the proper place inside
the body tube.
After you have the engine block and fins attached to the body tube, two slits are cut into the top of the body
tube just below the nose cone shoulder. The two slits form an opening that will become the shock cord attachment point.
This is the first time I have attached a shock cord in this manner. I have to say that this way is very solid, and
might outlast a standard tri-fold mount. The down side is the bump that is left on the outside of the body tube.
Once the shock cord is mounted, glue the launch lug on, and it is ready for primer and paint.
One thing I would like to mention, there seems to be two or three scans of instructions for the Mark on JimZ's
website. The instructions show two different launch lug mounting points. One set shows the launch lug mounted at a fin
root, the other set shows the launch lug mounted between two fins. However, I really don't think it matters where the
lug is mounted.
Finishing the Mark is very straightforward. Fill the balsa with the technique of your choice, prime, and paint. I
choose not to use any balsa fillers and just used a high build primer from a spray can found at most automotive parts
or home improvement stores.
After the rocket has been filled, primed, and sanded, paint the rocket the color of your choice. I would
recommend a highly visible color as this is a small rocket and can easily be overlooked. Especially in high grass.
I choose to paint mine like the cover picture, which has a red body tube and a gold nose cone. I used the same
gold "metal" paint for the nose cone that I used for my Golden Scout. I have not put the black stripes on
Construction Rating: 5 out of 5
Both Semroc and the Estes instructions recommend A8-3, B6-6, and C6-5 for engine choices. As I mentioned, I would not
fly this rocket on a C engine as you will most likely never see it again. I would suggest flying this exclusively on A
The maiden flight was on an A8-3. The flight was straight, fast, and high. I would guess that it went every bit
of 600 feet. Ejection was just after apogee. The streamer did not fully deploy though. I am not certain if the streamer
got stuck on the shock cord mount or if I put in a little too much cellulose wadding. The rocket came down a little
fast but landed in some tall grass and received no damage. Unfortunately, this has been the only flight so far.
There was a small dent on the top edge of the tube. I believe this was from the nose cone snapping back at
ejection. Lengthening the shock cord should eliminate this.
The recovery was fine except for the streamer not fully deploying. However, even if it did fully deploy, I still
think it would have come down too fast. I would recommend lengthening the streamer to get slower decent rates.
Flight Rating: 4 out of 5
Main PROs: Easy to build. Fast, high flights on low impulse engines. A great rocket for beginners and school
projects. A perfect rocket for small fields.
Main CONs: Short shock cord, short streamer.
Overall Rating: 4 ½ out of 5