Brief:
This is #3 of 10 "ready to build" models released by Semroc at NARAM-52. The original was one of Semroc's best-selling kits (released in 1970). The original kit introduced an ejection baffle, eliminating the need for wadding and simplifying flight prep. For this kit, the baffle is not included.

Construction:
Parts were excellent quality, and the sealed bag contained:

• Balsa nose cone
• Series 10 slotted body tube (1" ID)
• Series 9 stuffer tube (1" OD)
• 18mm motor mount (tube, metal hook, centering rings)
• Laser-cut balsa fins (3)
• Elastic shock cord
• 12" plastic chute
• Waterslide decals

The "ready to build" series is Semroc's answer to numerous requests for "ready to fly" rockets. In the RTB series, the modeler still has to actually do work to build and fly the model, but the design includes a number of features that simplify the build process, including slotted body tubes for thru-wall fin mounting, an alignment jig, and a stuffer tube to serve as shock cord anchor and reinforce the body tube.

The RTB series are all fairly easy to build, with almost all of the construction process using the same standardized steps. This is clearly a skill level 1 introductory type kit, and excluding finish/surface prep total construction is well under an hour.

The motor mount is a standard BT-20 tube, metal hook, and a pair of centering rings. Unlike the typical mount, though, there are two different centering rings involved with slightly different diameters. Pay careful attention to the instructions, as the white ring goes forward and the brown ring goes aft. This is critical later in the process. Surprisingly, the mount does not include an inner motor block, so the metal hook will have to hold for the life of the model. I found the centering rings a bit too snug, and had to peel off a layer of paper from the inside of each, plus one layer of paper from the outside of the white ring.

The stuffer tube contains a couple slits, which are used to slip the elastic shock cord through, serving as an anchor. After knotting the cord and reinforcing with a drop of glue, it's ready for the motor mount. The motor mount slides just a tiny bit into the stuffer tube, enough that the forward (white) centering ring is flush with the aft end of the stuffer tube. Do not slide the motor tube any further--the aft/brown ring is too large for the stuffer tube and instead is used to align inside the large series 10 body tube. Sliding the assembly into the body tube to dry fit is a good idea at this point, to make sure the forward centering ring is aligned properly inside the stuffer tube. Once the motor mount/stuffer tube assembly has completely dried, it can then be glued inside the body tube (though be careful to make sure the metal engine hook does not line up under a fin slot).

As noted, fins are thru-wall, and the fit against the motor tube was very good. Included in the kit is a nifty little cardboard fin alignment jig, which fits smoothly on the series 10 body tube and has notches to accept 3 and 4 fin patterns. The fixture fits well for most fins in the RTB series, though for fins that have a significant span and are not swept back very far, the slots in the jig are not long enough to be of much use. That was not the case with this model, though.

Finishing:
I went with the stock paint scheme on this, starting with two coats of primer, following up with a couple thin coats of gloss white, then masking off to paint the fins red and nose cone plus about an inch of body tube gloss black.

The waterslide decals add the name and roll pattern, and also include a neat little "powered by Semroc" decal that can go between the fins if you want that NASCAR-like look or just want to promote this great vendor.

Construction Rating: 4 out of 5

Flight:
I opted for a B6-4 for the first flight, finishing off a flight pack motor assortment (kit recommendation is for a -6 delay). The boost was straight, very fast, and respectable altitude, though probably closer to 300-400 feet than the header card's suggested 550. Part of that difference was surely my choice of delay, since the -4 clearly deployed early, leaving some potential coast altitude unfulfilled.

Recovery:
The 12" chute worked like a charm, as the model was recovered with no damage on dry/hard grass.

Flight Rating: 4 out of 5

Summary:
The 3FNC styling isn't exactly attention grabbing on the pad, but in terms of a simple to build, reliable flyer for an introductory model, this fits the bill. It's a bit pricey for the typical cub scout build/fly market, but as a kit to give to the kid who just bought one of those starter sets with models featuring plastic parts, this is a great way to introduce a young modeler to the wonders of balsa and glue construction.

Overall Rating: 4 out of 5