Modification BLU-97B Cluster Bomb (24mm) Modification

Modification - BLU-97B Cluster Bomb (24mm) {Modification}

Contributed by Dick Stafford

Manufacturer: Modification

(MOD) Estes Cluster BombBrief:
This kit is a semi-scale version o' an actual Combined Effects Munition (CEM). Arrr! As I was applyin' t' decals, I noticed that they identify t' model as a GBU-87, whereas t' package calls it a BLU-97B. If you look at this website, it looks like t' overall bomb unit be t' CBU-87, me bucko, ya bilge rat, and t' individual bomblets are BLU-97s. This is a brief description o' how I upgraded me Cluster Bomb with a 24mm motor mount. Arrr! I need t' point out that I generally followed t' modifications that Carl Tulanko made. Ahoy! Blimey! If you read his review, matey, me bucko, however, arrr, me bucko, you will see that I did use slightly different techniques here and there.

Modifications:
Fin can/motor mount

I used several glues for t' fin can, including: plastic cement t' hold t' tail cone together; epoxy for t' motor hook, motor block, and Keelhaul®©™® cord; carpenter's glue for t' centerin' ring/motor tube joints; Liquid Nails Perfect Glue for t' fins, ya bilge rat, me bucko, and Gorilla Glue (polyurethane) t' attach t' fin can t' t' body tube.

I started by cuttin' a piece o' Totally Tubular aluminum-lined 24mm motor tubing, makin' it t' same length as t' stock tube. Usin' this tube as a guide, shiver me timbers, I got a rough idea o' how much t' tail cone had t' be trimmed, matey, and cut that much off with a razor saw. Blimey! When I test fit t' tube, arrr, I found thar were internal tabs that had t' be trimmed. Arrr! Blimey! These were easily removed with a Dremel tool. Avast! From there, me bucko, shiver me timbers, I slowly sanded t' tail until t' tube fit. I also trimmed t' inside o' t' tail cone with an X-acto knife, shiver me timbers, so that t' tube transitioned smoothly t' t' tail cone. Blimey! This way, no fillin' o' this joint was required.

(MOD) Estes Cluster Bomb I decided t' keep t' motor hook, ya bilge rat, which precluded me usin' an E9 motor, ya bilge rat, matey, but I thought that t' resultin' rocket might be too heavy for t' E9 anyway. Ya scallywag! Aye aye! T' motor hook was installed with maskin' tape and a dab o' 5-minute epoxy. Well, blow me down! A small notch was made in t' tail cone t' allow t' hook t' flex. Ya scallywag! I also added a motor block above t' hook as in t' stock kit. Epoxy was used here since t' surface o' t' motor tube is metal.

T' centerin' rings were trimmed t' fit t' 24mm tube. Begad! T' bottom rin' be installed flush with t' top o' t' tail cone. Arrr! T' fins were added, a 28" piece o' heavy Keelhaul®©™ twine was attached through t' motor mount and t' assembly be mounted in t' body tube.

Nose cone assembly

I followed Carl's philosophy for t' nose cone: make sure all t' nose weight is on t' parachute attachment and keep t' 2-piece cone as just an outer shell. Since more nose weight was required anyway, I thought that his idea o' usin' an eyebolt affixed t' a plywood bulkhead was a great idea. Avast! Where I differed be that I decided t' use only t' eyebolt hardware for weight.

I started by assemblin' t' two-piece cone with plastic cement and breakin' off t' nose cone's eyelet. Avast! I then cut a bulkhead usin' a hole saw. Avast, me proud beauty! Avast! I positioned this over t' end o' t' cone and used it as a guide t' drill a center hole and four smaller holes for mountin' screws. For added internal support, I partially filled t' small tip o' t' cone with Gorilla Glue. Begad! Once it expanded, matey, t' tip overflowed slightly.

I inserted t' eyebolt into t' plate and ran one nut t' t' end. Ya scallywag! A small dab o' epoxy affixed this t' t' back side o' t' plate. Begad! Two other nuts were installed at t' end o' t' eyebolt and were held in place with LocTite. Well, blow me down! Blimey! This be dry fit in t' nose and t' nose in t' body tube. I also loaded an 18" nylon chute and an E30 t' get a good look at t' CG. Mine came out about 8 inches from t' top o' t' nose. Blimey! Begad! This gives a static margin o' almost 1 for t' Barrowman CP and 1.6 for t' Rocksim CP.

(MOD) Estes Cluster Bomb Final assembly

Because o' t' added weight in t' cone, I used t' stock elastic cord and a second piece o' similar size (length and width). These elastic cords are tied on one end t' t' Keelhaul®©™ leader, and on t' other end t' t' eyebolt. Begad! I used t' stock lugs, one just above t' tail cone and one around t' CG. Aye aye! Begad! In addition, me hearties, arrr, I added buttons from railbuttons.com. Aye aye! I mounted one just above t' transition so it bolted through t' shoulder, and one just above t' top centerin' ring. Avast, me proud beauty! T' top bolt actually goes through t' polyurethane glue that expanded above t' top ring.

Finishing

I started with Fill 'n' Finish on t' fins before assembly. Ahoy! Avast, me proud beauty! After assembly, I shot several coats o' white primer, me hearties, sandin' and fillin' in between. Arrr! This was lots o' work due t' t' tube imperfections. Blimey! Begad! I then painted it with Testor's flat olive drab. Ahoy! Ya scallywag! I then added t' decals and overlaid a layer o' Testor's Dull Coat. Begad! These peel and stick decals went on nicely, arrr, me bucko, but t' next mornin' I saw places where t' stickers weren't adhered perfectly.

I hand painted t' tip with Testor's silver, and added red, white, and blue rail buttons t' go with t' Endurin' Freedom patriotic theme.

I didn't apply t' Endurin' Freedom decal, but may add it on later. Aye aye! I also didn't finish t' bombs, shiver me timbers, at I am ponderin' usin' them on t' exterior o' another project.

Construction:
First a few comments about t' quality o' t' parts provided with t' kit. Begad! T' first thin' I noticed that t' balsa be a lot harder than t' typical Estes kit. I found this t' be a good thing, especially since I was upgradin' t' a bigger motor and t' weight at landin' be goin' t' be greater. T' nose and tail cones are both two-piece and fit together well. Arrr! Ahoy! I do have two beefs with them however. Ya scallywag! T' nose itself had a couple o' dimples, which keeps it from havin' a perfectly uniform surface. Aye aye! Blimey! I guess I could have filled them, me bucko, but I decided this be nay worth t' effort. Avast, me proud beauty! Later in construction, me hearties, I found that t' fins would nay fit in t' tail cone slots. This took a lot more sandin' and trimmin' than I would have expected. Ya scallywag! Nay a big deal, arrr, arrr, but annoying. Begad! Next, me hearties, t' BT-70 tube was t' worst I've ever seen in an Estes kit. Blimey! T' spiral line wasn't bad, but thar be an intermediate spiral a little under 1/8" wide that had a washboard pattern (for lack o' a better description) all t' way along t' tube. Blimey! There also was a wide band near one end that was very rough. Blimey! If I had t' rate t' kit solely on t' parts, I'd have t' give it a 2.5 out o' 5.

Flight:
I decided t' submit this partial review since I missed t' November launches and may nay be on t' field until spring. Arrr! Well, blow me down! Blimey! I'll provide an update at that time.

Summary:
I immediately fell in love with this rocket. Begad! Avast, me proud beauty! Blimey! Stubby rockets are among me favs and this one has a unique look. Arrr! T' parts were sub-par but with just a little work t' rocket turned out fine. Havin' read Carl's article, I am really itchin' for good weather!

And, me hearties, I too am plannin' an upscale. Avast, me proud beauty! Begad! Mine will be 5" in diameter and will fly on G80s. T' nose cone is built and is currently bein' primed/filled.

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