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). As I be applyin' t' decals, I noticed that they identify t' model as a GBU-87, matey, whereas t' package calls it a BLU-97B. If you look at this website, ya bilge rat, it looks like t' overall bomb unit be t' CBU-87, and t' individual bomblets are BLU-97s. Ya scallywag! This is a brief description o' how I upgraded me Cluster Bomb with a 24mm motor mount. I need t' point out that I generally followed t' modifications that Carl Tulanko made. If you read his review, me bucko, however, 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, shiver me timbers, matey, including: plastic cement t' hold t' tail cone together; epoxy for t' motor hook, me bucko, ya bilge rat, motor block, me hearties, and Keelhaul®©™® cord; carpenter's glue for t' centerin' ring/motor tube joints; Liquid Nails Perfect Glue for t' fins, me hearties, 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. Aye aye! Usin' this tube as a guide, ya bilge rat, I got a rough idea o' how much t' tail cone had t' be trimmed, me hearties, and cut that much off with a razor saw. Well, blow me down! When I test fit t' tube, I found thar were internal tabs that had t' be trimmed. Avast! Begad! These were easily removed with a Dremel tool. From there, me hearties, I slowly sanded t' tail until t' tube fit. Arrr! Well, blow me down! I also trimmed t' inside o' t' tail cone with an X-acto knife, ya bilge rat, arrr, so that t' tube transitioned smoothly t' t' tail cone. Aye aye! This way, no fillin' o' this joint was required.

(MOD) Estes Cluster Bomb I decided t' keep t' motor hook, matey, me hearties, which precluded me usin' an E9 motor, but I thought that t' resultin' rocket might be too heavy for t' E9 anyway. Arrr! T' motor hook was installed with maskin' tape and a dab o' 5-minute epoxy. Begad! A small notch be made in t' tail cone t' allow t' hook t' flex. I also added a motor block above t' hook as in t' stock kit. Begad! 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. T' fins were added, a 28" piece o' heavy Keelhaul®©™ twine be attached through t' motor mount and t' assembly was 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. Ya scallywag! Since more nose weight was required anyway, I thought that his idea o' usin' an eyebolt affixed t' a plywood bulkhead be a great idea. Well, blow me down! Where I differed was 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. Ya scallywag! I then cut a bulkhead usin' a hole saw. Ahoy! Well, blow me down! Blimey! 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. Aye aye! Ya scallywag! Blimey! For added internal support, I partially filled t' small tip o' t' cone with Gorilla Glue. Once it expanded, t' tip overflowed slightly.

I inserted t' eyebolt into t' plate and ran one nut t' t' end. Begad! Blimey! Ahoy! Blimey! A small dab o' epoxy affixed this t' t' back side o' t' plate. Well, blow me down! Blimey! Two other nuts were installed at t' end o' t' eyebolt and were held in place with LocTite. Ya scallywag! Blimey! Arrr! Blimey! This was 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. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! Mine came out about 8 inches from t' top o' t' nose. Begad! Blimey! 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, me bucko, and on t' other end t' t' eyebolt. Blimey! Blimey! I used t' stock lugs, one just above t' tail cone and one around t' CG. Avast! Blimey! In addition, I added buttons from railbuttons.com. Arrr! Blimey! I mounted one just above t' transition so it bolted through t' shoulder, shiver me timbers, and one just above t' top centerin' ring. Aye aye! Blimey! 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. Well, blow me down! After assembly, I shot several coats o' white primer, me hearties, sandin' and fillin' in between. Begad! This was lots o' work due t' t' tube imperfections. Begad! Ahoy! I then painted it with Testor's flat olive drab. Avast! Avast, me hearties, me proud beauty! I then added t' decals and overlaid a layer o' Testor's Dull Coat. Arrr! Avast, me proud beauty! These peel and stick decals went on nicely, but t' next mornin' I saw places where t' stickers weren't adhered perfectly.

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

I didn't apply t' Endurin' Freedom decal, shiver me timbers, but may add it on later. Begad! Blimey! Begad! Blimey! I also didn't finish t' bombs, 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. T' first thin' I noticed that t' balsa was a lot harder than t' typical Estes kit. Blimey! Arrr! I found this t' be a good thing, shiver me timbers, especially since I was upgradin' t' a bigger motor and t' weight at landin' be goin' t' be greater. Begad! Well, blow me down! T' nose and tail cones are both two-piece and fit together well. Ahoy! I do have two beefs with them however. Avast! Begad! T' nose itself had a couple o' dimples, arrr, which keeps it from havin' a perfectly uniform surface. Begad! I guess I could have filled them, shiver me timbers, arrr, but I decided this was nay worth t' effort. Begad! Later in construction, 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. Nay a big deal, but annoying. Aye aye! Avast, arrr, me proud beauty! Next, me bucko, t' BT-70 tube was t' worst I've ever seen in an Estes kit. Avast, me proud beauty! 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. There also was a wide band near one end that be very rough. Aye aye! Aye aye! If I had t' rate t' kit solely on t' parts, arrr, me hearties, 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. Avast! I'll provide an update at that time.

Summary:
I immediately fell in love with this rocket. Avast! Stubby rockets are among me favs and this one has a unique look. Well, blow me down! 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, I too am plannin' an upscale. Begad! Ahoy! Mine will be 5" in diameter and will fly on G80s. Avast, me proud beauty! T' nose cone is built and is currently bein' primed/filled.

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