Picture courtesy of LOC/Precision

Brief:
This model is a single-stage, three-motor, cluster rocket. It was designed for 24mm mid-power motors. Primarily D and E impulse motors.

Construction:
In this kit there are one body tube, three motor tubes, two 3/16" plywood centering rings, three 3/16" plywood fins, one 18" nylon parachute, one elastic shock cord and mount, 1/4" launch lug and a plastic nose cone.

The instruction for this kit were structured for modelers that have built a few rockets and understand how a rocket should be assembled. They explain the areas of the kit that differ from others in good detail. The order of construction was well thought out so you do not have to "go back" in the construction process. This kit is very easy to build.

The only area I wish I had paid more attention was motor retention. LOC does not include a method of retention in this kit. Which is good in my opinion. The builder can choose his/her own method of motor retention. I had the rocket completely assembled when I discovered how I wanted to retain the motors. The tree motor tubes are epoxied together in a pyramid style. During construction, a length of all-thread rod can be epoxied in the middle of the three tubes so that it extends past the aft end of the assembly. This way, the motors can be retained with a nut and washer. I had to "go back" and drill a hole in the epoxy for the threaded rod. It works very well.

If you do not use the all-thread style motor retention, remember to seal the gap between the motor tubes with epoxy. This will prevent venting the ejection gases rather than deploying the recovery system.

All the parts fit very well. I did not have to sand any of the parts to make them fit. I was a bit concerned about the fin method of fin attachment at first. The aft end of the motor tubes extend past the aft end of the body tube. This makes up a large part of the length of the rocket. The fins are attached at the motor tube joints. No through the wall mounts here. However, A little patience and a lot of epoxy in the fin to tube joints will pay off in the long run. Also I suggest an epoxy fillet in each motor tube joint. This will greatly increase the strength of the lower end of the rocket.

All in all, using good construction techniques and EPOXY, the Viper III turned out very sturdy.

Finishing:
The only "con" that I can say about this kit is the spiral grooves. Need I say more? The grooves in the body tube were no worse than an Estes kit though. I filled them with Elmer's FNF and they turned out smooth and invisible when primed and painted. The fins were coated with sanding sealer and sanded several times before priming. I used auto primer to start the finishing process. One light coat. Then sanded smooth. Any imperfection were filled with Squadron Green putty. Then primed and sanded until I was pleased with the finish. Krylon "Glowing Lemon Yellow" fluorescent paint was applied the to the main body tube. The nose cone, motor tubes and fins were painted gloss black. There were no decals included in the kit. This allows the modeler to add their own design. The model looks great after it's finished even without decals.

Construction Rating: 5 out of 5

Flight:
The recommended motors for this rocket are D12-7 and E30-7. I used three Estes D12-5's for the first two flights. Cellulose insulation was used for wadding. This stuff works great! It's cheap and can be bought at almost any building supply store. About three inches of the body tube full is enough. As I mentioned earlier I used a piece of all-thread epoxied between the motor tubes with a nut and washer for motor retention. I also epoxied thrust rings in the motor tubes to keep the motor from moving forward. If you plan to use motors longer than D's and E's, don't put any thrust rings in. Other motors will not fit. The day I flew it for the first time was near perfect. 5-10 MPH winds clear skies and the temp was around 80. I used the Estes ignitors that came with the motors. I have an Ignitorman kit, but didn't have time to make some up before this launch. Upon hitting the GO button the rocket lifted off very quickly and straight as an arrow. Beautiful flight. I guessimate altitude at approximately 1000'. Recovered close to the pads with no damage.

Recovery:
The shock cord is attached to the inside of the body tube using a small Kevlar® string. The string is taped to the tube so that a loop extends one inch from the end. Epoxy is applied other the end of the string and tape. This a very strong mount. The included elastic shock cord is then tied to the Kevlar® string. I tied a loop in the very end of the shock cord for the parachute to attach. The nose cone was attached about 18" from the parachute. The set up returned the rocket very nicely. It landed close to the pads at a rate that did cause damage upon impact.

Flight Rating: 5 out of 5

Summary:
This a great kit. I was kinda nervous about the first launch. It was my first cluster rocket. It assembled and finished very well. The flight can be summed up in one word. WOW! I haven't flown it on E motors yet. I can hardly wait.

Overall Rating: 5 out of 5

The following excerpt is from "Sport Rocketry". The intention is to allow guests to get a basic feeling about a kit. We strongly suggest that you get a copy of the referenced Sport Rocketry and read the entire article. Inside you will find many helpful hints in construction as well as other useful information. For more information, use the two links above.

"The components are solid, quality parts: plywood fins and centering rings, rugged cardboard tubing, plastic nosecone, and three 24mm motor mount tubes."
"A unique feature of this rocket is that the motor mount portion of the rocket is exposed..."
"Building the Viper III was quite simple."
"The instructions are clear and easy to follow..."
"There are no decals with the Viper III."
"It's unique, yet simple to build, and a solid performer."

The entire article gives the impression is that it a skilled modeler would enjoy this unique kit.