Thursday, December 30, 2010

Review: Essence Aerospace Technologies - Lambda-Class Shuttle (18mm)

This 18mm version of the Star Wars Lambda-Class Shuttle was produced in limited quantities by Essence Aerospace Technologies (EAT).  EAT was an off-shoot of Essence's Model Rocket Reviews and has been out-of-production for many years.  It was (and is) one of the most innovative rockets around.



Construction:

Parts:
* One 1/4" balsa sheet (3" x 6")
* Two 1/8" balsa sheet (6" x 7" each)
* One 3/32" balsa sheet (3" x 1")
* 3" 18mm motor tube
* 18mm thrust ring
* 18mm thin plastic, 2 piece nose cone
* 1/8" launch lug
* 24" Kevlar® shock cord
* 18" plastic parachute
* BB's
* Decal set

Tools/materials:
* Pencil
* Metric ruler (T-Square is recommended, but I didn't use one)
* X-acto-type knife with a new blade (I did follow this advice)
* Estes 18mm motor (spent or not)
* Wood glue - TiteBond Original is recommended
* 5-minute epoxy
* CA
* Masking tape
* Sand paper (220 grit) on a block
* Sand paper (220 grit) on a dowel
* Sand paper (400 grit) on and off a block
* Wood filler (Elmer's Fill-n-Finish, etc) or paper for lamination

This is not your typical kit with 3 - 4 fins to cut. The Lambda-Class Shuttle has 13 unique balsa parts and 19 total. The instructions were highly detailed with plenty of color photos. The kit includes a page of templates and a couple of alignment guides. The parts were all of nice quality, except I thought the nose cone was flimsy. I'm sure other cones could be substituted.

You first build the base assembly, which consists of three balsa pieces, the motor tube and motor block. This was straightforward and went together easily with wood glue. The Kevlar® shock cord is attached to the joint between the core and the motor tube with 5-minute epoxy.

You then cut out the large top fin and strengthen it. I laminated mine with drafting vellum and 3-M spray adhesive. The fin is attached to the top of the motor tube using the fin alignment guide. I used black rubberized CA in place of wood glue.

The canopy is constructed over the base and around the top fin. This consists of four balsa sections. The top and sides go on first and the rear plate later. I miss-measured ever so slightly and had to adjust the rear plate slightly. Luckily, I test fit the template before I cut balsa. At this point, I also I added the lower wing supports and let it all sit overnight.

I strengthened the lower wings the same way as the top. While this was drying, I filled and sanded the body.

For the nose cone, you start by gluing the shoulder into the cone with CA. I used black rubberized CA and accelerant to assemble the entire nose. After it is dry, you cut the top away at an angle that sets the downward slant of the upper nose cone plate. The shell of the cone consists of six balsa sections. You start by aligning the top plate with the body while it is laying on the surface of the cone that you just cut, and gluing it in place. With the plate flush with the body, I simply twisted the cone until it had the best fit. You then add the bottom and the sides. The side pieces have to be beveled and took some effort to assemble. I also found that the sides were a bit long, probably due to some problem with the angle of the nose cone (?). This was easily compensated for. The final step is filling the nose with BB's and epoxy. I ran out of five minute so I used 20 minute epoxy. I also threw in some #7 ½ lead shot to boost the weight, just in case I built the body too heavy. Building light is a consistent warning with this kit. Oh, and I almost forgot to set the shock cord in the BB/epoxy mix. This would have been a major problem. After the epoxy had cured, I sanded the edges and did some filling with fill-n-finish. The nose cone did live up to the reputation as being the most difficult part of the kit. Nevertheless, the cone looks fine and fits perfectly in spite of the few minor issues encountered.

Finishing:
In the final version, all balsa surfaces were filled with fill-n-finish. I gave it a couple of coats of white primer and then painted it with Wal-Mart brand chrome paint. It was supposed to be Plasti-Kote Car Color Ford Motors 8147 - Platinum, but I couldn't resist the cheaper paint. The kit included some decals, including one with the kit's serial number - mine is S/N #3. I also managed to wrangle an extended set of decals that weren't in the kit. Thanks, Nick! Theses decals were some of the easiest to work with, possibly because they came pre-coated.

Flight:
I carefully packed the chute and stuffed it into the cavity next to the motor tube. I repacked it a couple of times and it still seemed too tight to me. And it was. I flew the Shuttle twice on a C6-3 and a B6-2. Both flights were straight and it appeared to try to fly parallel to the ground after burn out. This rocket was in general a crowd-pleaser and really caught the attention of the visiting scout troop! On the first flight with the C6-3 the chute didn't budge, but it landed without damage. On the second flight, the chute almost deployed. This time the top fin snapped off.

In summary, while this rocket looks awesome and flew nicely, the large 18" chute and the short 18mm compartment made recovery problematic.