1000 lb Laser Guided Bomb

Modeled by: Stuart Lenz

This design is modeled on a GBU 16 – 1000 lb Laser Guided Bomb that is produced from a 1000 lb Cast Iron Bomb and an upgrade made by Lockheed/Martin Corp. It is likely that bombs like this were used in the recent gulf war. While the prototype (seen in thumbnail photo) was based on Micro Maxx engines, this was upscaled to use 3*18mm engine mounts for the contest version.

The engine mount was made by gluing three identical engine tubes together in a standard triangle configuration and attaching 3 engine hooks. The thrust rings were then glued into the end of each engine tube with a piece of braided Kevlar@ tied to one of the thrust rings. This was then glued into one end of the 18” Bt 60 and holes in both ends of the ogive nose cones was cut and trimmed to fit the Bt 60 much like a V2 tail cone. This was then all glued together using epoxy. The space around the engine tubes and Bt 60 was filled with glue soaked tissue.

The second nose cone was cut off similar to the first one to slide over the Bt 60 tube for the main part of the LMC add on. The nose cones were then fitted together end to end to produce the body of the bomb, with 1 5/8” of Bt 80 between them.

Once the engine mount was dry, the tail cone was marked and cut for the fin slots. The fins themselves were cut from 3-ply plywood material and build up from three layers. The fins were then glued to the engine mount through slots in the tail cone and to the tail cone using a generous amount of epoxy. These fins were slightly increased in length and span to improve stability.

The upper parts of the Laser Guided assembly were fabricated by drilling a ¼” hole in the end of the transition, fitting a 2” long ¼” plastic tube into the hole and carving/sanding the transition to taper up to the ¼” tube. The shock cord was attached to the Kevlar and this assembly, which will act as the nose cone for the finished rocket. The laser tracker unit was added on to the end of this tube and made from the remaining nose cone and 1” of Bt 20 and 5/16” of Bt 60 as the ring fin and 4 small fins to support the ring fin. A 1” piece of 5/16” plastic tube was centered in this unit, which will then slide over the ¼” tube. This laser tracking unit is removable and can be launch as a separate rocket using a MicroMaxx Engine (with the addition of a launch lug).

The launch lug was attached to the Bt 80 between the two large nose cones and the upper steering fins were attached to the Bt 60 tube centered on the exposed length. These fins were slightly decreased in length and span to improve stability.

The rocket was flown on August 14th 2004 at the Tripoli Minnesota high power launch. On the first attempt using 3*B6-4 Estes engines, the GBU 16 stuck on the launch rod when only 2 of the engines ignited, a second attempt, also on 3*B6-4 engines, flew to about 200 ft, deployed the parachute and landed with only a bottom fin popping off. The GBU 16 was photographed the next day after a easily repair to reattach the fin and touch up paint.

Parts

1. Ogive Nose Cones 2 * Bt 80 from Estes V2/Silver Comet
2. Body tubes Bt 80 (1 5/8”), Bt 60 (18”), Bt 20 (1”)
3. Transition Bt60/5 Gemini-Titan (60AB)
4. Round Nose Cone Bt 20
5. Engine Tube 3* Bt 20 (3”)
6. Thrust Rings 3* Bt 20/5
7. Centering Rings As Required
8. Kevlar String As Required
9. ¼” elastic shook cord As Desired
10. Launch Lug 3/16 (2”)
11. Parachute or Streamer As Desired (24” PML used)