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. Avast, me proud beauty! It was a favorite o' mine when I be 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, arrr, shiver me timbers, 10" in length, matey, arrr, 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, ya bilge rat, 2 CR-78 centerin' rings, 1 TB-7 thrust block, shiver me timbers, and 1 standard 18mm engine hook)
  • Semroc LL-122 launch lug, arrr, 1/8" diameter x 2" length
  • shock cord, 36" length o' 1/8" sewin' elastic
  • screw eye
  • 12" plastic or mylar parachute

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

T' build was relatively simple and straightforward. It was very much like buildin' a two-stage rocket but with no motor mount in t' sustainer. The original Excalibur used die-cut fiber fins, ya bilge rat, ya bilge rat, but I found t' 1/16" balsa ones quite adequate. Ahoy! I used Aleene's Tacky Glue for t' engine mount assembly and t' tack t' fins in place followed by wood glue fillets. Avast, me proud beauty! Avast, me proud beauty! 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! 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 was assemblin' a kit rather than buildin' a clone. 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 be a lot o' balsa to seal--a nose cone, balsa reducer, ya bilge rat, and 2 sets o' fins. 3 coats o' AeroGloss sandin' sealer, me hearties, sandin' with 400 grit sandpaper in betwixt coats filled the balsa grain. Ahoy! Avast, ya bilge rat, me proud beauty! T' entire rocket was then sprayed with 2 coats o' Krylon primer, again sandin' betwixt coats. Avast! This was followed by 2 coats o' Krylon semi-gloss white.

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

Fortunately, matey, I did nay have t' figure out how t' make t' decals, as they were a gift from Carl at Semroc. Aye aye! Avast! Those o' you with ink jet printers can make them from t' JimZ scans or if you lack a suitable printer, ya bilge rat, 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. Begad! Ya scallywag! Estes waddin' be stuffed into t' lower body tube and t' carefully folded 12" Estes parachute placed on top. Avast, me proud beauty! T' rocket shot off t' pad very quickly, and the flight be straight with no noticeable windcocking. Avast! Aye aye! 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. Ahoy! T' ready availability o' parts makes it a perfect rocket for first time cloners. Blimey!

Overall Rating: 4 out o' 5

comment Post a Comment