Picture courtesy of ARC     

Brief:
This is a parallel staged rocket. The four 13mm boosters detach while the main body continues on its 18mm core motor. This vehicle has four fins on an 18mm by 5.5" long core. The 13mm x 5.5" boosters attach in between each fin. The main body transitions to a 32mm body tube, which separates in the middle for parachute deployment. Each booster is recovered by its own streamer.

Construction:
The parts were top quality totally tubular tubing and high quality balsa nose cones and transition. The fins were laser cut, and the recovery system was an ASP sport chute with Kevlar shock cords. The instructions are extensive and include many excellent photographs. This kit is definitely meant for experienced builders, and it requires pre-fitting all parts and patience.

There are two areas where the builder needs to take care. One area is during the attachment of the lower launch lug. Due to the transition from the 32mm main body tube to the 18mm core tube a standoff is called for in the directions. You are directed to cut a standoff from balsa and glue the lug to it. The directions are unclear here, but you must glue the lug the the EDGE of the balsa, not the surface. Instead, I attached my lower launch lug to a fin and it works fine.

The second area that needs care is in the positioning of the booster forward mount retainers. The instructions indicate the retainers glued to the right of an alignment line (and this is what the directions state). I had to center the retainers on the alignment line to get the boosters on straight. Both of these issues were easily overcome and not a significant problem for an experienced builder.

Finishing:
This model has small tolerances between the boosters, the core, the interlocks and forward retainers. Care must be taken not to build up too much paint/primer in these areas. The tubing is top quality and I had no problem with the finish.

Construction Rating: 4 out of 5

Flight:
1/4A3-2, 1/2A3-2, A3-4 and A10-3 are all recommended for the 13mm boosters. A8-3, B6-6 and C6-7 are recommended for the core. The kit was shipped with a special flight instruction manual for those inexperienced in clusters etc.

The model is designed so that the boosters will fall away from the core and then eject the streamers while the core continues on. This is best achieved with boosters with a short burn (A10-3) and long burn core motors, but should work as long as the boosters burn out before ejection from the core motor.

My model flew straight and true with complete separation of boosters and deployment of all recovery devices. I had one failure, when the core motor failed to light (probably due to detachment of igniter clip prior to launch). The motor was recovered with minor damage to one fin. I experienced a little scorching of the main body tube transition by the booster ejection charge during this flight (the boosters did not separate until ejection - probably due to the slow speed). Motor retention is by friction fit, and I used cellulose wadding.

Recovery:
Kevlar is used for the entire booster shock cords, and is attached to the motor block. The main recovery harness is Kevlar and elastic and seems satisfactory. The ASP parachute is very nice and easy to assemble, and appears adequate for this light model. I lost a booster nose cone, shock cord and streamer. The only thought was that the Kevlar burned through - or had flaw/weak spot. There is plenty of room in the main body tube for wadding and the recovery system. The streamers fit well in the boosters, but there is less room for wadding etc.

Flight Rating: 4 out of 5

Summary:
I do not feel there are any major cons involved. The instructions are being updated by the company to clear up any confusion. This is a complex kit, and should be purchased/flown by modelers of intermediate/advanced levels of experience. This model looks and flies impressively - a real crowd pleaser! The quality of the materials, and the obvious thought and care put in by the designers is a major plus! Customer service by the company is excellent.

Overall Rating: 4 out of 5