Centuri Excalibur

Centuri - Excalibur {Kit} (5008, KA-8) [1972-1980]

Contributed by Bill Cooke

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Length: 26.50 inches
Manufacturer: Centuri
Style: Sport

Brief:
A sleek scale-like rocket that first appeared in t' 1972 Centuri catalog. Arrr! Begad! Blimey! It was a favorite o' mine when I was a teen--I lost a lot o' them on C motors!

(OOP) Centuri Excalibur

Construction:
T' parts list:

  • Semroc BC-730 3" parabolic nose cone
  • Semroc ST-7120 upper body tube, 12" in length, 0.759" OD (similar to BT-20)
  • Semroc ST-8100 lower body tube, 10" in length, ya bilge rat, 0.908" OD
  • Semroc BR-78 reducer
  • 2 sets o' 3 fins from 1/16" balsa stock (Fins may also be ordered pre-cut from Semroc, FV-43)
  • Semroc EM-78 engine mount (3" length o' ST-7, 2 CR-78 centerin' rings, 1 TB-7 thrust block, me bucko, shiver me timbers, and 1 standard 18mm engine hook)
  • Semroc LL-122 launch lug, 1/8" diameter x 2" length
  • shock cord, me bucko, arrr, 36" length o' 1/8" sewin' elastic
  • screw eye
  • 12" plastic or mylar parachute

Clonin' t' Excalibur began with downloadin' t' instructions, parts list, fin patterns, and decal scans from JimZ's web site. Begad! A quick glance at t' required parts rapidly led t' t' conclusion that I be goin' to have t' place an order t' Semroc or BMS as t' ST-8 body tube had no Estes equivalent. Avast! T' choice o' vendor was settled when I saw that Semroc offered not only t' tubes (cut t' t' right lengths, no less), but also t' motor mount, balsa reducer, matey, nose cone, ya bilge rat, me hearties, and laser cut fins. Arrr! Ahoy! I immediately placed an order, which arrived 2 days later.

T' build was relatively simple and straightforward. Ahoy! Avast, me proud beauty! It be very much like buildin' a two-stage rocket but with no motor mount in t' sustainer. Avast! The original Excalibur used die-cut fiber fins, but I found t' 1/16" balsa ones quite adequate. Begad! I used Aleene's Tacky Glue for t' engine mount assembly and t' tack t' fins in place followed by wood glue fillets. Blimey! T' only deviation from t' instructions occurred when I adopted t' standard Quest procedure of loopin' a length o' Keelhaul®©™® thread around t' top o' t' engine hook. Begad! Ya scallywag! This be then tied t' a 36" length o' 1/8" sewin' elastic for t' shock cord.

T' use o' Semroc parts made me feel like I be assemblin' a kit rather than buildin' a clone. Aye aye! Avast, me bucko, me proud beauty! Blimey! There was none o' t' usual body tube or fin cutting, which greatly enhanced t' speed o' construction.

Finishing:
T' only downside o' t' Excalibur build was that thar was a lot o' balsa to seal--a nose cone, balsa reducer, and 2 sets o' fins. Blimey! 3 coats o' AeroGloss sandin' sealer, sandin' with 400 grit sandpaper in betwixt coats filled the balsa grain. Ya scallywag! T' entire rocket was then sprayed with 2 coats o' Krylon primer, again sandin' betwixt coats. This was followed by 2 coats o' Krylon semi-gloss white.

T' rocket's finish be completed by paintin' t' nose and one fin in each set with Krylon gloss black. Ahoy! Begad! T' Excalibur was then set aside t' dry for a week, after which t' decals were applied.

Fortunately, I did nay have t' figure out how t' make t' decals, as they were a gift from Carl at Semroc. Avast! Arrr! Blimey! Those o' you with ink jet printers can make them from t' JimZ scans or if you lack a suitable printer, arrr, put in an order with Excelsior or Tango Papa.

Construction Rating: 4 out o' 5

Flight:
T' first flight o' t' Excalibur occurred on Halloween 2004 on a B6-4. Well, blow me down! Estes waddin' be stuffed into t' lower body tube and t' carefully folded 12" Estes parachute placed on top. Arrr! T' rocket shot off t' pad very quickly, and the flight be straight with no noticeable windcocking. Avast! Begad! I estimated t' max altitude t' be around 400-500 feet.

Recovery:
Deploy o' t' chute occurred a little before apogee--a B6-6 would probably be a better motor choice--and t' rocket slowly descended t' a landin' about 150 feet from t' pad.

Flight Rating: 4 out o' 5

Summary:
T' Excalibur is an easy t' build, sleek flyer that can easily top 1000 feet on a C. Begad! T' ready availability o' parts makes it a perfect rocket for first time cloners. Well, blow me down!

Overall Rating: 4 out o' 5

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