Semroc - Mark II {Kit} (KV-1)

Contributed by Alan Tuskes

Construction Rating: starstarstarstarstar
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar
Diameter: 1.04 inches
Manufacturer: Semroc
Skill Level: 1
Style: Clone, Sport

Brief:
The Mark II is a single stage Retro-Repro kit of Orville Carlisle's Rock-A-Chute Mark II model rocket. It is, as noted by the history sheet that came with the kit, not a clone kit, but rather a reproduction of a classic kit updated with the latest technology and building components.

Construction:
Opening the packaging and laying out the contents revealed what would be an easy build, using the high quality components that Semroc is known for. The package contents included:

  • 1 Precision turned balsa nose cone
  • 1 Series 10 body tube
  • 1 Series 7 to 10 engine mount kit (engine tube, engine hook, thrust ring, 2 centering rings
  • 1 BT-3 launch lug
  • 1 Recovery kit (Kevlar® and elastic shock cords, screw eye, 12" parachute kit)
  • Extremely clean laser cut balsa fins.
  • Instructions and history of the Rock-A-Chute
  • No decorative decals, however there is a name plate decal, which includes the name of the kit, and a production number.

I got the Mark II as part of my purchase from a Hobby Lobby sale at the end of December 2005, so what better way to ring in the new year than hanging in The Rocketry Forum chat room and building this kit at my desk.

Yeah. I know. Get a life...

Anyway, the instructions are straightforward, starting with assembling the EM-710 motor mount. The engine tube even comes pre-slotted, so there is no question about where the motor hook goes. Semroc does have a better trick for attaching the Kevlar shock cord attachment than what I usually use and it's a real forehead slapper. (You know...you smack yourself in the forehead and say "Now why didn't I think of that?") I usually loop the Kevlar around the engine tube and notch the centering ring to allow the Kevlar to exit the body tube. Semroc has you just tie the Kevlar around the engine block itself and glue that into place. It is much less work and as long as you use a good grade of glue (because of the attachment point, I glued the block in with wood glue and reinforced with a dab of 5 minute epoxy), it isn't going anywhere.

While that assembly is drying, I put the #10 body tube on the fin marking guide that was printed on the instructions. I personally prefer the wraparound type, but the way Semroc does it maintains the integrity of the instructions (which are printed on a good grade of cardstock, interestingly enough...) for filing away for future use and perhaps allowing them to be preserved for a generation of yet to be born BARs? The three fins themselves are extremely clean laser cut and pretty much fell away from the surrounding balsa. I sanded all edges except for the root edges round and used my handy yellow plastic Estes fin attachment tool to attach the fins with wood glue. After those were set, the engine mount was installed (again with wood glue) and the Kevlar shock cord is fed through the front of the body tube, attached to the generous length of elastic shock cord, and then to the beautifully turned balsa nosecone via the included screw eye. Finally, the oversized launch lug (accurately reflecting Carlisle's original) is attached to the body tube.

Finishing:
I gave the nose one and fins a coat of thinned Elmer's Fill 'n' Finish. The next morning, I sanded them smooth and hit the rocket with a shot of sandable primer just to make sure the grain wasn't too obnoxious. That was then followed by a couple of coats of red spray paint, then one fin and the nose cone were masked for a shot of black. With that it was called finished, and I assembled and installed the 12" plastic Semroc parachute. The rocket was then ready for the January 8th Sky Buster launch!

Construction Rating: 5 out of 5

Flight:
Well, the January 8th launch was canceled for poor field conditions and since most of the flyers are HPR guys, a lack of a waiver due to changing of the officers, so there was no big launch that day. However, not being one to let a mid-winter 45 degree day go by, I packed my rockets, my daughter, and myself up for a launch at Lakewood park.

Semroc recommends the following engines: A8-5, B6-6, C6-7. The only one's I had out of those 3 were the C6-7s, but the park wasn't big enough for those motors in that rocket. I did, however, have some Quest A6-4s and thought that would be even better that risking too short a delay with the A8-3s I did have. Since the park is also surrounded by trees, I swapped out the chute for a streamer for the first flight. My daughter hit the launch button and the Mark II shot arrow straight into the sky, popping the streamer at apogee, which I estimate to be possibly 200 feet. As there was virtually no wind, the rocket landed maybe 30 feet away from the pad with the streamer recovery resulting in no damage. For the second flight I put the chute back in the rocket in place of the streamer, and launched again with my last A6-4. Once again, arrow straight flight, popping the chute right at apogee or maybe just a breath thereafter. This time, there was a little drift but nothing serious. The 12" chute is just the right size for a rocket this weight. Recovery was right next to but not quite in a mud puddle. A few swipes with a baby wipe cleaned the crud off the gloss paint. This little bad boy is looking to cut loose on a real field this spring!

Recovery:
There was no damage at all. I used dog barf for wadding and it proved to be adequate protection for the recovery system. The chute is the right size for a rocket this size and weight, but the rocket is small, light, and sturdy enough that a streamer can also be used easily.

Flight Rating: 5 out of 5

Summary:
PROs: Very simple, inexpensive replica of a historic model rocket that can be put together in an hour or so (depending on how slow setting your glue is) at one sitting. Good performer. Good beginner kit without being insultingly simple (i.e., Rip the package open and launch).

CONs: I can't think of any.

Overall Rating: 5 out of 5

Flights

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