Estes BLU-97B Cluster Bomb

Estes - BLU-97B Cluster Bomb {Kit} (2055)

Contributed by Steve Kristal

Construction Rating: starstar_borderstar_borderstar_borderstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstar_borderstar_borderstar_border
Diameter: 2.22 inches
Length: 14.40 inches
Manufacturer: Estes
Skill Level: 2
Style: Scale

Rock PicsBrief:
I was doing a rocket launch for Science Day at my kids' school. Since the field was small, I wanted something slow and low. Since the spectators were young, I wanted "something special" and I thought the "spits out nerdlets on streamers" factor would be a big plus. Since I wouldn't have time to reload between classes I knew I would have to build 6 rockets of each type I was launching (the Snitch, and Cosmic Cobra were the other two types I chose), so cheapness and Level 1 construction were a must. And since there was no way I could call or finish these as "Cluster Bombs" for little kids, I thought the 10" long fat tube would be perfect for a colorful wrap.

Wel,l I was right on 4 out of my five requirements. The only one I was wrong on was that these were Level 1 construction projects. A combination of poor design and shoddy parts made building 6 of these far more time-consuming and aggravating than I expected. I knew these were ridiculously cheap rockets, considering the number of parts, but these kits weren't up to the usual Estes standards. A Mosquito is a Level 1 rocket. An Alpha is a Level 1 rocket. A motor-mount-overhang, two-part-boat-tail, through-the-wall-fins, clay-in-the-two-part-nosecone is not a Level 1 project. Add in parts that don't fit and an unsecured aft motor mount and you're closer to a Level 3.


The first “gotcha” is in the motor mount. The construction is the usual Estes type, with the difference being that both centering rings are far forward of the engine hook. You're instructed to place a mark inside the aft end of the body tube and then glue the mount in place. If you do this before you do the next step, building the boat tail (“tail cone”), you can't use the tail to line up the motor mount. The aft end of the motor mount appears to be designed to end just short of the end of the tail cone, leaving it unsecured at it's aft end. Since I read the directions prior to gluing in the motor mount, I built the boat tail first thinking the aft end of the motor mount tube must rest in the end of the plastic boat tail. But the end of the boat tail is of a smaller diameter than the motor mount tube (it's the same diameter as a motor). Thus it's the motor itself that provides lateral stability for the motor mount tube. What's really needed here is either another, smaller, centering ring, or some flanges inside the boat tail that center and stabilize the motor mount. It's not that this is such a high performance product that this is critical for flight, but it means the motor-mount tube moves all over when you are trying to check the fit of the through-the-wall-fin fin-tabs. Basically you need to insert a motor while you're building the rocket in order to adjust the length of the fin-tabs.

The second “gotcha” is that on all six kits the notch in the boat tail, through which the engine hook is to fit was too narrow for the width of the hook. I simply enlarged it on the first rocket I put together before realizing I'd been had by the third “gotcha” which is that the notch is directly in line with the fin slot in the boat tail. This means you're supposed to glue that fin to the engine hook? This is the only rocket I've ever built suggesting you insert a lever between the fin and body tube! For the remainder of the rockets I Dremeled an engine-hook notch at a spot halfway between two fin slots. Really not a Level-1 construction technique.

The final “gotcha” was the fins and fin-slots. The directions tell you to “Test fit fins in slots on tail cone. Sand as needed for a proper fit.” Easier said than done since this was a two-part “gotcha”. The fin-slots on all six rockets were significantly narrower than the fin stock. Okay, you're probably going to have some variance in fin stock so err a little on the narrow side for the slots to make sure the fins are tight. A little sanding would be OK. But the difference between the two was really significant, probably 25% of the fin width. For the first rocket fin (out of the 24 I did) I tried alternately sanding one side of the fin tab, then the other, trying to keep the fin tab centered in the fin. That was such a pain that I eventually decided to widen the fin slots. I eventually figured out that folding a quarter sheet of 220 sandpaper lengthwise in half, and then in half again, produced a giant sized “emery board” that could be slipped through two fin slots at once and would fairly quickly enlarge the slots enough to take the fins.

The second part of this “gotcha” was that now that I had fins that fit in the slots, the tabs were too long. The directions tell nothing about this but the solution I came up with, because of the unsecured motor mount, was to insert an engine (the yellow engine spacer is too flimsy), write a number on each fin and corresponding fin-slot, and sand the tabs to fit. Okay, after the fins are all glued in place they do act to center-stabilize the motor-mount tube. But unless you figured out some way to hold the tube in place while sanding the fins to fit, you're going to end up with an off-center motor-mount. One that you probably can't even slide an engine into considering the proximity and narrowness of the aft end of the boat tail. Again, not really a Level 1 technique.

As for the rest of the assembly, it was fairly straightforward. If you've built lots of rockets before, there are no show-stoppers. But there's no way anyone should think of buying this kit for someone's first rocket. If you haven't built a number of rockets with motor mounts and through-the-wall fins, this kit would be extremely frustrating.


As for finishing, I made colorful wraps to size on my computer and printed them out from my inkjet printer on full-size label paper. The best technique I found was to put a little centering mark in the center of the top and bottom of each wrap. I drew a centering line down the middle of each rocket using a piece of aluminum angle-iron. (Because I had already put the launch lugs on, I put my line on the opposite side of the launch lugs. I've used this technique again since, but I do it before putting on the launch lugs, then cut out a small spot for the lugs.) I then cut the wraps to size, and tore away a thin strip of backing paper down the middle of the wrap. I lined it up at top and bottom, then pressed it into place, starting from the center and working out toward the top and bottom of the tube. I then removed the backing paper from one side at a time and, working from the center out towards the back side of the rocket, repeated the sequence. It works well, avoids bubbles, and allows for better alignment than trying to line up one edge of the wrap with the centering line. If you make your background color black, you can fill in any tiny gap on the back side with permanent marker (I also used permanent marker to color the launch lugs). I then sprayed the wrap with two coats of Rustoleum clear, and let those dry for 24 hours before masking off the body to paint the fins and tail. I painted the clear first because I wanted to be sure the masking tape wouldn't ruin the paper wrap. Be sure to test whatever spray you're using first on some scrap wraps because one of the acrylic clear coats I tried made all the ink run. The clear coat soaks through the paper so whatever is underneath will show through any light areas. For that reason I erase all but the very top and bottom of my centering line before putting on the wrap. I also spray non-white tubes white when using the technique on other rockets for the same reason. If you've not done this technique before, you'll be surprised at how vibrant the inkjet colors turn after you spray them with the clear spray paint (see photo). The size and color of the body tube, as well as the cost, on this rocket make it perfect for your first attempt at a wrap.

Construction Rating: 1 out of 5


As for flying, in spite of all the construction problems, this is a real crowd pleaser. It flies great, and is sturdier than I expected. I used B6-4s to keep the ejection low enough so the kids could see the action. Be sure to keep the rod straight up though when using B's. These rockets only hit 150' max on a B so angling the rod on my first shot caused an almost-lawn-dart (which the kids liked anyway). I basically think of this rocket, with colorful wraps, ejecting nerdlets, and flown on B-engines, as a big version of a New Year's Eve “Party Popper”.

Flight Rating: 5 out of 5


All in all, I'd give this rocket a 5 for flight, a 5 for Potential Creativity, and a 1 or 2 for construction. If Estes cleans up the construction problems it should be in their lineup for a long time to come.

Overall Rating: 2 out of 5

Other Reviews
  • Estes BLU-97B Cluster Bomb By Max Handly

    This is Estes new 1:6.4 scale BLU-97B Cluster Bomb. The rocket is fat (2.25") and short (14"). It comes with 4 "cluster bombs" which are small, about 1.5 inches long that get ejected at deployment and streamer to the ground. The kit contains: one body tube two part nose cone (cut in half) two part tail cone (with through the tube slots!) die-cut balsa fins bomblets ...

  • Estes BLU-97B Cluster Bomb By Carl Tulanko

    The Estes BLU-97B Cluster Bomb Model Rocket Kit is one of four new Estes "Military" kits recently released; a nice salute to our boys overseas. I purchased the kit on August 11, 2003, as soon as I saw the first ones in the store and had it built and flown by the following weekend. I have to say all four of the new Estes kits are pretty cool, but this cluster bomb with its short, stout look ...


comment Post a Comment