Semroc - Arcon {Kit} (KV-7)

Contributed by John Lee

Construction Rating: starstarstarstarstar
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Diameter: 1.04 inches
Length: 20.00 inches
Manufacturer: Semroc
Skill Level: 1
Style: Scale

A semi-scale, 4FNC, 18mm, payload, parachute recovery, retro repro of a Centuri rocket by Semroc. This is another of my retroactive reviews of a rocket that was built before I found EMRR. I am doing it from memory with the instructions in front of me. I received the Arcon as a freebie with a large order from Semroc. Since it is a simple model, I decided to try it before tackling some of the more complex ones.

The kit came as a standard Semroc hanging bag with standard Semroc parts. That means that everything was FIRST RATE. The parts inventory was as follows:

  • Body Tube ST-10105
  • Body Tube ST-1050
  • Body Tube ST-730E
  • Balsa Nose Cone BC-1045
  • Laser cut fin sheet FV-7
  • Balsa Tube Coupler BTC-10
  • 2 Centering Rings CR-710
  • Thrust Ring TR-7
  • Launch Lug LL-122
  • Engine Hook EH-28
  • Screw Eye SE-10
  • Elastic Cord EC-124
  • Kevlar® THread SCK-24
  • Plastic Parachute RC-12
  • Tape Disc Sheet TD-6
  • Shroud Line SLT-6
  • Decal DKV-7
The instructions for the Arcon are printed in a nice booklet. They are clear and well illustrated as to be expected from this company.

Construction begins with the engine mount assembly. The Kevlar® thread is slipped under the motor hook and the thrust ring is glued into place. The centering rings are then slid into place and secured with glue.

The fins also are simple. They are of good quality and practically falling free from the balsa on their own accord. A light sanding prepares them for mounting. I rounded the leading and trailing edges as well as the tips. The BT is marked for placement by standing it on a guide printed in the instructions. Lines are drawn and extended as needed.

Before mounting the fins, the motor mount is inserted. It slides into the main BT and is secured with glue. The Kevlar® is then fished through the BT and tied to the elastic.

The fins are mounted by the simple expedient of gluing them to the marked lines and the launch lug is glued equidistant between 2 fins.

This rocket is designed to be a payloader. A balsa coupler joins the lower BT to the upper one and is fitted with the eye screw. The nosecone completes the forward end and is held in place by friction.

With that, it is time to assemble the parachute which follows the standard plastic parachute schema.

PROS: Great quality parts and great instructions. Great kit for learning the rudiments of building.
CONS: none

Finishing is where I really fell down on this rocket. I think it was the last one on which I used standard sanding sealer. The sealer was applied to the fins and NC then sanded. The process was then repeated ad nausem. I emphasize the ad nausem part because my wife made sure I heard her objections to the smell (I didn't think that was possible with somebody who likes to fix kimchi). Eventually, I thought it was ready for paint. I was not at this time sophisticated enough to realize that spirals are the mark of the amateur and did not fill mine in.

I primed the rocket with gray because that is what I had on hand. For the finish itself, however, I had chosen a nice metallic purple for the body and a deep red for the fins and NC. I had no idea what I was doing. The body drank up many coats of the purple and afterwards you could not see any of the metallic finish. If I had done something silly like read the painting instructions, I would have learned that this paint was for engine blocks and assembled a metallic base.

The fins and nosecone were relatively easy. I masked the body and sprayed the red. That part worked out fine. After the paint dried, I applied the roll pattern decal. It was lost on the dark purple.

All in all, this is not a good looking rocket as I built it. That is my own fault and not that of Semroc.

PROS: a simple design which should be easy to paint effectively.
CONS: I did it my way

This one gets a 5 for the kit and a 2 for my treatment of it.

Construction Rating: 5 out of 5

The recommended motors for this kit are A8-3, B6-4, C6-5.

The maiden flight was on an A8-3. It took off, spun a bit around its long axis and deployed right on time. It was not a spectacular flight except that, at this time, any successful flight for me was spectacular.

The second and third flight were both on B6-4s and were in all respects identical to the first flight except in terms of altitude.

After that, the rocket sat for a long time before I flew it again. When I did, it was on a C6-5. It really went high and drifted far. I thought I had lost it but it eventually was found. I have since launched it successfully on an A6-4 as well. This rocket has the potential to fly well. For me, it flies reliably even if not spectacularly.

PROS: Dependable, Simple
CONS: none

Flight Rating: 4 out of 5

I think this is a good intro rocket. It teaches the basic skills and can look very nice. It improved my skill set, inspired me to find something besides sanding sealer and reliably worked. Mine will never win any beauty contests but I am happy with it.

Overall Rating: 4 out of 5


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