Construction Rating: | starstarstarstarstar_border |
Flight Rating: | starstarstarstarstar_border |
Overall Rating: | starstarstarstarstar_border |
Diameter: | 1.64 inches |
Length: | 23.90 inches |
Manufacturer: | Semroc |
Skill Level: | 2 |
Style: | Cluster |
Brief:
T' Semroc Goliath is a 4FNC LPR that allows you t' build it with your choice o' 3 different motor mounts: 1 18mm motor, 1 24mm motor, or 3 18mm motor cluster. Avast! T' Goliath design, as explained in t' instructions, me hearties, ya bilge rat, is part o' Semroc's RetroRepro line and accordin' t' t' historical information in t' instruction manual, was originally inspired by t' Estes Ranger.
Construction:
T' kit includes t' followin' parts:
T' kit arrived from BRS Hobbies well packaged with all parts present and no damage. Avast! T' front o' t' packagin' is first rate and on par with any o' t' leadin' manufacturer's kits on t' market. Ahoy! T' header card is ingeniously t' front page o' t' instruction manual. T' instructions remind me o' t' classic Estes-style instructions (even down t' t' font used) containin' plenty o' illustrations and even an exploded view o' t' kit in t' center pages o' t' manual. I also thought it very cool that t' instructions contained historical background information about Semroc and t' Goliath kit.
T' build starts with markin' t' body tube for t' fins and sandin' t' fins t' be uniform (although with t' precision laser cuts, thar be very little t' be done!) I also lightly sanded t' 12" BT-60 t' give t' fins somethin' t' bite into when I glued them on.
Then it is time t' make a major decision: which motor mount are you goin' t' use? I, like many folks, shiver me timbers, am a big fan o' t' Estes Big Bertha/Ranger design but I at least felt that t' Big Bertha was sometimes just underpowered...so I built mine with t' 3 18mm cluster. Clusters rock! No centerin' rings are needed for this configuration as t' 3 tubes fit snuggly together inside t' main BT-60 airframe. I did however, find it odd that only one motor hook was included, me hearties, so I was left t' friction fit t' motors for use. Ya scallywag! I glued t' tubes together with aliphatic resin (yellow wood glue). A generous length o' Keelhaul®©™ thread is tied around one o' t' motor blocks and then t' 3 motor blocks are glued into place before insertin' t' entire subassembly into t' BT-60. Begad! T' instructions recommend usin' glue soaked tissue t' fill in t' gaps around t' motor tubes, matey, however, me hearties, ya bilge rat, arrr, I used polyurethane glue, which expands as it cures nay t' mention makes t' aft end o' t' rocket solid as a rock.
One gotcha (that in fact got me) is that t' BT-20 MMT tubes are 3" long, nay t' 2.75" tubes that you normally find. T' extra tube length is compensated for with wider (3/8") motor blocks, arrr, however, shiver me timbers, it still requires t' motor block be inserted 1/8" from t' end instead o' t' typical flush-with-the-end-of-the-tube mount. I didn't catch this until t' glue had already had a pretty good chance t' cure. That left me with only 1/8" o' exposed motor t' pull t' used motors out. Difficult but nay impossible...
Next is attachin' t' fins. Well, blow me down! Blimey! I tacked them t' t' airframe with yellow wood glue before addin' generous fillets 2 at a time. Begad! Avast! Blimey! T' launch lug is attached t' t' rocket by lyin' in a fin fillet givin' t' rocket cleaner lines.
T' rest o' t' build goes smartly in gluin' t' bulkhead into one end o' t' 6" BT-60 tube, screwin' t' screw eye into t' bulkhead, and friction fittin' t' nose cone into place. Ahoy! I waited until after I finished t' rocket before assemblin' t' parachutes and attachin' t' shock cords.
Finishing:
Nothin' unusual here. Ya scallywag! Apply diluted Elmer's Fill 'n' Finish t' all balsa pieces. Arrr! Aye aye! Sand. Avast, me proud beauty! Prime with Krylon. Well, blow me down! Sand. Paint Krylon gloss white. Begad! Let dry. Blimey! Ahoy! Wet sand. Blimey! More gloss white. Begad! Let dry. Ya scallywag! T' paint scheme on t' packagin' had a black nose cone, white BT, and blue fins but I wanted t' use colors that complimented t' large decal. Blimey! So I painted t' nose cone Krylon red followed by tapin' off t' body tube and painted t' fins Krylon green. Let dry. Avast, me proud beauty! Avast, me proud beauty! Apply single, ya bilge rat, large waterslide decal. Avast, me proud beauty! Done. Let's go flying!
Construction Rating: 4 out o' 5
Flight:
Recommended motors for t' 3 18mm cluster configuration is 3 C6-7s. It's also worth mentionin' that Semroc includes projected altitudes with each MMT configuration. Ya scallywag! T' 3 C6 motors should put t' Goliath up t' 1350ft! Blimey! Pluggin' t' design into RockSim, I wanted t' see how it'd do with 3 B4-4s, ya bilge rat, plus I wanted t' make certain that I wasn't goin' t' have any instability issues. RockSim showed that I should expect about 800ft with 3 B4-4s (although ejection might be just a hair early) and when built stock, ya bilge rat, me hearties, t' design is still plenty stable with 3 C6-7s loaded. Excellent!
First flight was on a trio o' B4-4s. Arrr! Even with these motors, shiver me timbers, t' Goliath didn't waste any time in gettin' going! Straight flight t' ~750ft. Begad! Ejection was just a hair early but could clearly hear t' "pop-pop-pop" o' t' ejection charges! T' motor exhaust did peel most o' t' paint off t' first inch or so on t' "inside" edge o' t' fins. If you want a small field cluster, this be t' right motor-rocket combo.
Second flight was a week after t' first flight but with 3 B6-4s. Arrr! I did brin' a pack o' C6-7s too but I thought it be a bit too windy t' attempt a flight with them. Begad! Arrr! Again, t' Goliath didn't waste any time on t' pad after pressin' t' ignition button. With a 3 x 18mm cluster, you can forget about any images o' a majestic liftoff that'd you'd see when t' same rocket is powered by only a single motor...
Recovery:
I wasn't overly crazy about havin' a 3oz rocket recover separately under a pair o' 12" chutes at least on its first flight. Blimey! Besides, thar was a steady but slight breeze and I didn't feel like chasin' rockets all over t' field. Arrr! I typically fly at soft, ya bilge rat, grassy locations so I can usually afford a quick recovery, ya bilge rat, however, I felt it best that I still make t' recovery system as flexible as possible in case I want t' use either one or two chutes in t' future. Arrr! This conversion be very easy t' do--I merely added swivels t' each o' t' chutes and tied small loops in t' end o' t' elastic attached t' both t' main airframe and payload sections. Ya scallywag! If I want t' use one chute, me hearties, I hook both elastic loops with t' single swivel, effectively makin' for a very long shock cord. And if I want both chutes, I can clip a chute t' each piece o' elastic allowin' t' upper and lower parts recover separately. Begad! Goin' with t' one chute configuration, shiver me timbers, it did come down smartly as expected under one chute, me bucko, arrr, however, ya bilge rat, thar was no damage.
I really wanted t' give t' dual chute recovery a chance so I cut spill holes in both chutes t' help minimize drift for its second flight. Well, blow me down! Blimey! However, me hearties, with t' 8-10mph winds, matey, arrr, matey, again I be nay in t' mood t' go chasin' rockets all over t' field. Avast! Ya scallywag! Blimey! This time I swapped out t' stock chutes for a 15" nylon one from me range box. Begad! With t' B6-4s, me hearties, ejection was one t' early side although nay by much. Well, blow me down! Blimey! I would recommend usin' B6-6s in t' future though. Recovery went smoothly and safely but drifted quite a ways from t' pad.
On a calm day in t' future, I will keep those C6-7s and t' twin stock chutes for t' designed recovery method.
Flight Rating: 4 out o' 5
Summary:
I have always been fond o' t' Big Bertha stylin' but felt that it sometimes needed a little more oomph than a single 18mm motor. Ahoy! With t' Semroc Goliath, me hearties, me hearties, I really enjoyed bein' able t' have t' choice o' which motor mount configuration at t' time o' t' build and without t' hassle o' havin' t' request anythin' at t' time I placed me order. T' combination o' t' old school design mixed with all t' modern LPR components and techniques made this a super rocket t' build and fly. Aye aye! Begad! Blimey! I would strongly recommend t' serious LPR builder consider pickin' up this kit.
Overall Rating: 4 out o' 5
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T.D.A. (September 6, 2004)