Semroc Hydra One

Semroc - Hydra One {Kit} (KA-18)

Contributed by Chan Stevens

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar_border
Diameter: 1.17 inches
Length: 22.10 inches
Manufacturer: Semroc
Skill Level: 3
Style: Futuristic/Exotic

Hydra I

Brief:
This is a 70% downscale o' Semroc's popular Hydra VII, me bucko, which is a 7-motor cluster design. Avast! This is a greatly simplified single-motor version, although it still shares most o' t' design characteristics that make t' Hydra VII a fun and challengin' build.

Construction:
T' good news is this smaller version sells for about $20 less than t' Hydra VII. Ya scallywag! T' bad news is that still makes this list for $26, which would make it one o' t' most expensive rockets I've ever flown on an A motor. Begad! Still, me hearties, for that $26 you get plenty o' top-quality parts:

  • Balsa nose cone (main)
  • Kraft paper body tube (main)
  • BT-80 rin' tube
  • BT-20 motor tube
  • ST-560 stuffer tube
  • 6 slotted body tubes (trim)
  • 3 balsa nose cones (trim)
  • Laser-cut fins (lots)
  • Keelhaul®©™ elastic shock cord
  • waterslide decals
  • 12" plastic chute

Hydra I

When Carl announced this kit at NARCON 2009, he mentioned that he built t' prototype in about an hour. Arrr! He's apparently a lot faster than I am--I think I had maybe 7-8 hours into it plus finishing, and finishin' is a lot o' work on this compared t' other models o' similar size.

T' instructions are well written, easy t' follow, me bucko, and use Semroc's new format with pre-punched holes and fold-out instructions designed t' be retained in a binder. Arrr! It's rated a skill level one, me bucko, matey, shiver me timbers, but I think that's pretty optimistic and would rate it at least a 2, shiver me timbers, possibly a 3 on t' 5 scale. Ya scallywag! Ahoy! This is nay a simple beginner's model.

T' motor mount is simple enough--a BT-20, arrr, slotted for a metal hook. T' stuffer tube is a bit unusual. Arrr! Ya scallywag! It gets a thick wound centerin' rin' on one end, which in turn is bonded inside t' forward end o' t' motor tube actin' as both a centerin' rin' for t' stuffer tube and a motor block.

Next, me hearties, t' outer trim body tubes go on surroundin' t' motor tube and sittin' flush against t' stuffer tube. These fit perfectly as they are pre-slotted. Ya scallywag! Begad! Blimey! That's a big time-saver and one o' t' reasons t' price for this kit is nay too bad once you get into it. T' 6 slotted tubes fit perfectly around t' perimeter o' t' inner tube.

Hydra I After t' tube glue joints have cured out, you add a couple o' centerin' rings t' t' inner/stuffer tube with t' forward o' these also servin' as t' anchor point for t' Keelhaul®©™ shock cord. Blimey! Aye aye! T' upper body tube fits over these.

As with t' Hydra VII, matey, matey, you get t' split some balsa nose cones in half t' mount flush around t' outside o' t' inner tube. Begad! I used a very thin razor saw for a clean cut then wrapped some 180 grit paper around t' body tube t' sand a curved contour onto t' backside o' each cone. Arrr! I held off bondin' these though until after paintin' (see finishin' notes).

T' fins on this wind up bein' a lot o' work, matey, especially if you're anal-retentive about cosmetics and fill t' grains on each before bonding.There are 6 main inner fins, me hearties, 3 larger outside fins, and 12 smaller fins flankin' t' larger outside fins. Well, blow me down! Blimey! 21 total fins t' sand, me hearties, seal, sand, fill, me bucko, etc. Arrr! On top o' that, shiver me timbers, I painted them separately before bondin' t' save maskin' trouble later.

You'll want t' read t' directions carefully before workin' t' fins. In me case, me bucko, betwixt me deviation from t' routine/plan o' paintin' some parts offline first, matey, combined with a cursory readin' o' t' instructions resulted in a goof I didn't catch until t' very end when I noticed 3 leftover smaller fins. Begad! Aye aye! I'd botched t' fin alignment marking, however, me hearties, me hearties, me finished bird looks fine.

In a nutshell, me hearties, thar are 6 inner fins that go in t' joints betwixt trim tubes. Begad! Avast! These also act as braces/supports t' which t' BT-80 rin' fin is bonded. In me case, t' fit was a bit sloppy, ya bilge rat, me bucko, so t' ID o' t' BT-80 rin' fin is about 1/16" larger than t' diameter o' t' braces' outer surfaces, so I had t' pinch it in just a little t' get it t' properly bond. With t' rin' fin in place, you then mount t' 3 main fins aligned with 3 o' t' inner braces and 12 o' t' outer fins per t' markin' guide provided with t' kit. Ahoy! Aye aye! T' markin' guide does nay show t' position o' t' 3 main fins, just t' 12 trim fins, and I didn't catch that t' outer trim fins were not supposed t' line up with any o' t' inner braces.

Hydra IHydra I

Anyway, once all t' fins are on, thar are just a few simple steps left. First, arrr, a tail cone shroud made from a cardstock pattern sheet goes on t' aft end, then t' screw eye goes in t' nose cone, followed by attachin' 3 little wood dowel "guns" as trim t' t' main fins.

Sure seems like a bit more than an hour's work...

Finishing:
T' cover art depicts a decent gray and white contrastin' color scheme. T' achieve that though would require some pretty challengin' masking. Avast! Blimey! I wimped out and opted t' pre-paint many o' me detail parts t' eliminate t' more difficult mask jobs.

I started by sortin' t' parts into two piles--one t' wind up gray, t' other t' wind up white. T' gray pile included t' nose cones (split and main), me bucko, BT-80 rin' with 3 main fins already bonded, me bucko, and 6 inner fin braces. T' white parts included t' body tubes and 12 outer/trim fins.

I then sanded/scraped off t' bond surfaces and attached t' inner/brace fins. Ya scallywag! Well, blow me down! While those were drying, I tacked on t' outer trim fins t' t' BT-80 rin' tube. Begad! That finished assembly then went on t' t' inner braces. Avast! Ahoy! I tacked t' gray split nose cone halves into t' exposed forward end o' t' little body tubes.

I finished up by hand paintin' t' guns gloss black and t' tail cone a metallic silver.

I wrapped up by applyin' t' waterslide decals. As usual, they were terrific quality and texture, me hearties, arrr, me hearties, very good t' work with, and dryin' absolutely clear.

Construction Rating: 4

Flight:
For t' maiden flight I was a bit limited, me hearties, me bucko, flyin' it on a small field roughly 250 square yards surrounded by dense tree growth. Begad! Begad! Even though t' winds were light, matey, I didn't want t' chance losin' all me work t' a tree so I went with a B6-4.

T' flight was dead straight, and t' 4 second delay was just right as it deployed while still hangin' at apogee horizontally aligned. T' altitude was a good deal less than t' estimated 300 on t' kit's header card. Blimey! Blimey! I'd say I be more like 150-200 feet, me bucko, although me finished model weighed in at 2.3 ounces (without motor and wadding) versus t' 1.9 on t' header.

Recovery:
T' 12" plastic chute furnished with t' kit worked fine and brought it gently back down. Avast! Ahoy! No trees involved. Avast, me proud beauty! Begad! It landed on t' very short grass, sufferin' no damage. Ya scallywag! Even t' little dowels stickin' out beyond t' fins survived fine.

Flight Rating: 5

Summary:
This turned out t' be a pretty nice little build project, ya bilge rat, matey, and t' finished rocket is certainly more appealin' than 3FNC designs. Avast, me proud beauty! I do find t' gray/white paint scheme a bit borin' and would suggest somethin' more along t' lines o' t' original Hydra VII with red and blue accents though.

Overall Rating: 4

Flights

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