Brief:
This kit is a 3FNC (3 Fins and a Nose Cone) piston-ejection, streamer duration competition rocket. The "ELM" stands for "Extremely Low Mass." It is a companion kit to its only slightly larger brother the Stratos-18 ELM.

Construction:
My kit came with balsa nose cone, two sheets of 1/32" balsa fin stock, balsa nose block for the piston, a Kevlar® shock cord, an elastic shock cord, engine block, launch lug, white BT-5 body tube with very fine groves and a light glassine coating. The instructions were written onto a compact disc in PDF format. Even though the kit comes with two sheets of balsa, only one is needed.

I ordered both the Stratos-13 and Stratos-18 together. When they arrived I found that the body tube had been bent beyond use by the post office. I sent Carlos at Heavenly Hobbies an email about the tube and he sent me out a replacement right away and free of charge. I built the Stratos-18 while waiting for the replacement BT-5. As that only took a few hours of build time to complete, I decided to use a "modular" approach to assembling the rest of the rocket.

First I cut the fins from the 1/32" balsa fin stock. To protect in from chipping or splitting, I covered the back with blue painters tape. After the fins were cut I decided not to round the edges. At that thickness I don't think it would have made a difference and why take the chance on splitting a freshly cut fin.

Next I assembled the engine block and Kevlar® shock cord. A groove gets cut into the outside surface deep enough to fit the shock cord in to it. I secured it using a bowline knot and set it with CA.

After that came the nose cone and elastic shock cord. According to the instructions, the elastic cord is to be knotted at one end and stuffed into a pre-drilled hole. There was no hole. I used a 1/8" drill bit to make one. The balsa also looked a bit soft so I coated it with CA and allowed it to harden. Following that came a brushed on layer of thinned Elmer's Wood Filler. Once that had dried I sanded it down until smooth. To finish up I pushed the elastic knot into the shoulder of the nose and secured it with 30 minute epoxy.

All that left was the streamer. All I did there was fold one end into a point and tie on a 9" section of Kevlar® cut from the length provided. I used hole reinforcements to keep it from tearing out.

When the body tube arrived at last, it was time to put everything together. Engine block in, fins on, tie shock cords to one another. I do need to mention that as the rocket uses a balsa block as its piston. It comes with a small hole drilled through it and threaded on to the Kevlar® shock cord. Knots are tied above and below the piston to hold it in place. The piston provided was a good bit narrow and had to be built up with masking tape. This may actually be a good thing as I'll cover in a moment.

Finishing:
I left the rocket unfinished as it is supposed to be a competition rocket. The only finishing I did was the before mentioned work to harden the nose cone.

Construction Rating: 5 out of 5

Flight:
For its maiden flight I used an A3-4T. With the piston ejection it requires no wadding. Place an igniter in a motor and place the motor in the rocket. The motor is friction fitted and secured with two wraps of masking tape. The take off was right quick and blended in with the overcast skies.

Recovery:
I was able to track the rocket once the ejection charge blew. Then I knew I had a problem. Somehow the nose and streamer had separated from the rest of the rocket. The body landed gently in the flying field but the nose and streamer continued to drift toward the road. It landed gently enough but balsa was never intended to hold up against cars. The nose cone was crushed. Turns out that the Kevlar® shock cord snapped at the piston. It was either too thin, too short, or a combination on the two. Also, after the flight the piston was a bit resistant to go in. I peeled off a bit of the masking tape and all was fine. It was cool and damp when I flew and that may have had something to do with it.

Flight Rating: 4 out of 5

Summary:
This was a very nice little kit. I would not recommend it as a first kit as you need a motor case to set the engine block in place. It would work well as a first completion kit as long as the builder had some experience with cutting their own fins from stock.

Overall Rating: 4 out of 5