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. Well, blow me down! Aye aye! 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, me hearties, shiver me timbers, 12" in length, 0.759" OD (similar to BT-20)
  • Semroc ST-8100 lower body tube, matey, 10" in length, 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, shiver me timbers, me bucko, 2 CR-78 centerin' rings, 1 TB-7 thrust block, matey, and 1 standard 18mm engine hook)
  • Semroc LL-122 launch lug, 1/8" diameter x 2" length
  • shock cord, ya bilge rat, me hearties, 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, ya bilge rat, and decal scans from JimZ's web site. 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. Ahoy! T' choice o' vendor be settled when I saw that Semroc offered not only t' tubes (cut t' t' right lengths, ya bilge rat, no less), but also t' motor mount, balsa reducer, matey, nose cone, and laser cut fins. Avast, me proud beauty! Ya scallywag! I immediately placed an order, which arrived 2 days later.

T' build be relatively simple and straightforward. Ya scallywag! It was very much like buildin' a two-stage rocket but with no motor mount in t' sustainer. Begad! The original Excalibur used die-cut fiber fins, but I found t' 1/16" balsa ones quite adequate. Avast, me proud beauty! I used Aleene's Tacky Glue for t' engine mount assembly and t' tack t' fins in place followed by wood glue fillets. 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 was 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. Ahoy! There be 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. 3 coats o' AeroGloss sandin' sealer, sandin' with 400 grit sandpaper in betwixt coats filled the balsa grain. Ya scallywag! Aye aye! 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. Arrr! T' Excalibur was then set aside t' dry for a week, ya bilge rat, 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. Blimey! Avast, me proud beauty! Those o' you with ink jet printers can make them from t' JimZ scans or if you lack a suitable printer, arrr, 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. Estes waddin' was stuffed into t' lower body tube and t' carefully folded 12" Estes parachute placed on top. Aye aye! Aye aye! T' rocket shot off t' pad very quickly, and the flight be straight with no noticeable windcocking. Ya scallywag! 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, shiver me timbers, ya bilge rat, shiver me timbers, sleek flyer that can easily top 1000 feet on a C. Well, blow me down! T' ready availability o' parts makes it a perfect rocket for first time cloners.

Overall Rating: 4 out o' 5

comment Post a Comment