Brief:
This is a semi-scale model of the GBU-24 Paveway III laser guided bomb. It flies on 18mm motors and recovers under a 12" chute. You can find more info on the actual bomb [here] .

Construction:

• One BT-55, 10 7/8" long
• Plastic tail cone/adapter (separated during construction)
• Two BT-20 tubes, 5" long
• Seamless elliptical plastic nose cone, BT-20
• Cardstock centering rings
• Engine hook
• Engine block
• Mylar retainer ring for the engine hook
• Launch lug, 1/8"
• Elastic shock cord, 1/8" x 18"
• Assembled 12" plastic chute
• Die cut balsa fins, 3/32"
• Die cut balsa fin protectors, 1/16"
• Peel and stick decals
• Enduring Freedom sticker (not used on model)

The first step is to assemble the motor mount. This is a typical build, and consists of the BT-20 motor mount, two centering rings, an engine hook, a Mylar retainer for the hook, and a motor block. I used carpenter's glue as recommended. Before installation in the main body tube, I epoxied a two-foot section of Kevlar® twine onto the mount, trough the top ring.

Next, I removed and sanded the fins, and filled them with Fill 'n Finish. The main fins were fine, but the protectors, which attach on either side of the rear fins, were very thin and warped badly when exposed to the moisture in the Fill 'n Finish. I pressed these as they dried and they straightened out.

The tail cone and transition come as one unit and must be separated. A razor saw is suggested, but I used an Exacto knife. The bottom of the tail cone must also be trimmed and sanded, as do the fin slots. The latter start as rectangular projections, which are cut off with a razor saw, forming the slots. The final trimming is supposed to be the top of the transition. The instructions have you cut this off, leaving a hollow unit with both the top and bottom open. The shock cord then attaches to the inside of the upper body tube using a paper mount. Instead, I poked a small hole in the recessed ridge just below the top of the transition, fed a loop of Kevlar® twine through the hole and around the transition (see photo). This formed a loop, which the elastic cord will later attach to. A small dab of 5-minute Epoxy on the hole and knot holds the twine in.

The tail cone is used to adjust the depth of the motor mount as it is glued into the main body tube. Once positioned, the tail cone is attached, making sure the engine hook is centered between the fin slots. I used black rubberized CA in place of the recommended plastic cement.

The lower fins are mounted through the slots in the tail cone. I found these slots to be excessively loose, so they didn't support the fins well. I applied yellow glue to the fin tab and the front root section. To hold the fins while this glue set, I used Liquid Nails Perfect Glue, Type 1 on the rear root section. This sets fast and the fins were good to go. There is a marking guide for the top fins, and these were attached with carpenter's glue. After the rear fins set, you position the fin deployment guides and mark their position. A thin layer of yellow glue is applied to fins up to the mark, and the guides are attached. These immediately warped like crazy, so a couple of small clamps were required on each guide/fin/guide 'sandwich' as they set. Afterwards, these still seemed flimsy, so I added a small strip of scrap balsa between each pair at their roots.

The final steps prior to finishing was the launch lug and Fill ' Finish fillets. I didn't' glue the top tube to the transition or the cone until finishing was complete. When they were connected, I again used black CA.

After finishing, all that was left was tying the elastic cord to the Kevlar® leader in the body tube and the Kevlar® loop on the transition. I stashed the cute that was provided and will use a 12" nylon chute.

Overall, I give this build a 3 1/2. It all went together easily with the exception of the fin deployment guides, which should have been made of thicker material. The dimensioning of the fin slots on the tail cone also wasn't good. Luckily any 'slop' is hidden by those guides. One thing that stood out to me was the quality of the nose cone - it is completely seamless.

Finishing:
I started with fill-n-finish on the fins and tubes before assembly. I found the spirals on the BT-55 to be shallow, but the ones on the top BT-20 were deeper, and required some filler. After assembly, I shot several coats of white primer, sanding and filling in between.

The instructions say to use olive drab and red spray paint, a silver paint pen, and to follow the paint scheme on the cover. The cover picture shows the fin section, top fins and nose cone to be olive drab, and top BT-20 to be more of a tan then red. I used Testors' spray for the olive drab sections. In the photos on the link I presented in the intro, the top tube seems to be somewhat of a rust colored red. I decided to use red paint, which did get toned down as it was overlaid over the olive drab. I tested some Krylon red on a piece of wood, and it seemed to be OK. However, some bubbles formed when I used it over the Testor's paint on the model. Maybe the base coat was thicker on the model. After the first red coat dried, I sanded the bubbles and re-coated it. This time it covered just fine.

There are silver bands shown at the base of the BT-55 and BT-20 tubes. Instead of silver paint, I used some chrome Trim Monokote for these stripes. Finally, I applied the peel and stick decals.

Overall, the finishing was fairly typical, however I found the separation in the side plates where they extend ahead of the main fins made spraying a little more difficult than usual. I give it a finishing rating of 4.

Construction Rating: 3 out of 5

Flight:
I decided to submit this partial review since I missed the November launches and may not be on the field until spring. I'll provide an update at that time.

Summary:
I saw my first 'bunker buster' rocket over a year ago and have really wanted to build something similar. When I saw this model, I knew that it would satisfy my cravings.

The model was not a difficult build, and I think a skill level 2 rating is about right. I liked the plastic parts, especially the nose cone, and think the thru-the-wall fin attachment is great. However, the fit of the fins was poor and the balsa used for the fin protectors was flimsy. As with the Cluster Bomb BLU-97B that I just built, it appears that Estes needs to pay more attention to quality control. Still, the rocket was fun to build and looks *very* cool.