Semroc Space Plane (xKit)

Semroc - Space Plane {Kit}

Contributed by Chan Stevens

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar
Manufacturer: Semroc
Semroc xKit Space Plane

Brief:
Semroc had released a series o' "cc:" (carbon copy) kits a few years ago that were essentially bags of parts t' clone an Estes or Centuri classic, but with no directions, me bucko, shiver me timbers, instead pointin' t' modeler t' reference sites that archive t' original instructions online. While this be generally a well-received product niche, me bucko, t' cc:'s were discontinued in 2007 due t' occasional customer confusion over lack o' instructions.

Fast forward t' 2008--Semroc has brought back t' bag o' parts concept as xKits, and now offers them only online, hopin' that if you're on t' ball enough t' get through an online shoppin' cart process, you can probably figure out how t' pull up online instructions from Jim Z's site.

T' Space Plane be originally sold in 1961 as t' first mass-produced boost glider kit, Estes number K-3. Arrr! Blimey! It features some somewhat complex aspects t' achieve t' transition from boost t' glide--spin tabs for rotational stability, matey, and elevons locked in horizontal trim by t' motor, which spits out enablin' them t' sprin' upward.

T' first cc: version o' t' kit was based upon an ST-7 tube size (0.759" OD), ya bilge rat, me bucko, but in t' xKit offerin' it now matches t' original Estes BT-30 tube (0.767" OD). Avast, me proud beauty! Begad! T' kit retails for $11.50.

Construction:
T' bag o' parts contains t' typically excellent Semroc quality materials:

  • BT-30 body tube, me bucko, 5.5"
  • Balsa nose cone
  • Laser-cut balsa fins (time-savin' upgrade from t' Estes version)
  • Balsa motor block/bulkhead
  • Adhesive plastic hinges/disks (substantially improved over Estes version)
  • Trim screws (nylon)
  • Lead nose weight
  • Waterslide decal (upgrade/not included in Estes version)

Since this is an xKit, shiver me timbers, Semroc does nay provide directions, but includes a link t' t' JimZ archive site, where the original instructions can be found in both TIFF and PDF formats. Aye aye! This kit is a close enough reproduction that the original instructions work fine.

Buildin' was somewhat challengin' although you are aided a good bit by t' laser-cut parts. I would rate this in the neighborhood o' a 3 on t' 5 scale o' complexity, matey, due t' some o' t' challenges with fit/alignment and trim. My total build time was just under two hours, arrr, me hearties, plus finishing.

Semroc xKit Space Plane Construction begins with t' fuselage (body tube). You'll need t' print out t' marking guide form t' original instructions, which is then used t' draw lines for t' wings, launch lug and control tabs, plus to cut out t' aft section which later serves as vertical stops/limiters for t' elevons. Arrr! You then glue in t' balsa bulkhead and "attach" t' nose cone, matey, but I found two things worth tweakin' here. Ya scallywag! Ya scallywag! First, arrr, matey, given today's hot ejection charges, treatin' t' aft end o' t' bulkhead is an absolute must. I used a thin layer o' epoxy. Second, matey, shiver me timbers, shiver me timbers, you should nay "attach" t' nose cone with any semi-permanent glue yet, as t' thin' has nay been trimmed and nose weight will be needed later.

Next comes assembly o' t' wings and elevons. T' wings are initially held together by a pair o' tape disks. Ya scallywag! Pay careful attention t' t' orientation, arrr, as t' laser-cut parts even have tiny laser-scratched location semi-circles on each win' half for use in placin' t' tape disks. Well, blow me down! With t' win' halves tacked together (no glue yet!), t' elevons are then taped in place at t' trailin' edges. Well, blow me down! Aye aye! T' tape strips provided is very high tack and rugged--I was impressed. As long as you don't have any balsa dust on t' surface you're bondin' to, t' tape hinges should prove t' be very durable.

Semroc xKit Space Plane I'll admit I be a bit confused by t' next step, which was bondin' and trimmin' tiny elevon stops. Begad! T' instructions show a part that starts out as a rectangular balsa strip, me bucko, which is then sanded t' an almost fin-shaped pattern, stressin' that t' 3/32" width o' t' balsa stock must be used as t' height o' the finished piece. Aye aye! T' laser-cut parts were trapezoid shaped and usin' t' 3/32" height would have made t' shape irrelevant. Ahoy! Once I started dry-fitting, matey, though, I realized that t' trapezoid was designed t' match t' top/interior surfaces o' t' elevons, and that no sandin' was needed--they simply act as small wedges t' form a tight fit once a motor's inserted. A SLIGHT taper might help make for an easy ejection/transition. Avast, me proud beauty! Arrr! See close-up photo for how these look once bonded.

Semroc xKit Space Plane T' win' dihedral is achieved very simply--the flexible, taped-together assembly gets a generous bead o' glue t' t' top surface (with t' tape disks), arrr, ya bilge rat, and this is then placed upside-down on t' body tube with t' win' tips restin' flat on t' table surface. Aye aye! Allowin' for overnight drying, shiver me timbers, I then added t' stabilizers and spin tabs on t' win' ends (pay careful attention t' t' positionin' o' t' spin tabs--also supported by laser-etched lines on t' balsa parts).

T' last aspects o' construction are t' bond t' elevon lockin' plates t' t' bottom (keeps them from getting pushed below horizontal/causin' a nose-down dive), matey, arrr, t' launch lug, and t' mountin' plates for t' nylon trim screws. T' trim plates were hard 3/32 balsa, but Semroc still suggests reinforcin' with a coat o' CA. This is a good idea although in me case t' holes were slightly undersized and reinforcin' with CA should have been done after openin' them up, nay before.

An elastic cord is then attached from t' elevons up around t' launch lug, ya bilge rat, arrr, pullin' t' elevons up whenever they're free t' float (e.g., after motor ejects). Begad! T' nylon screws can then be turned t' adjust t' amount o' angle for each elevon, which helps create lift as well as introduce a turn for easier recovery. Ya scallywag! In me case, I needed t' use most of t' provided nose weight and then a fair amount o' up elevon for a good hand glide, and t' glide was very fast.

Semroc xKit Space Plane

Finishing:
Normally gliders are best left unfinished other than basic moisture protection such as thinned dope, matey, but in this case, given that it's nay exactly a competition/performance model and that it came with nice decals, I decided t' give it a very light white primer coat followed by two light coats o' gloss white. I did nay bother fillin' grains, as that would have just added weight, but I did sand everythin' down with 320 grit sandpaper before painting, and made sure to round t' leadin' and trailin' edges as well.

I finished up by applyin' t' waterslide decals, me bucko, me bucko, which were typical Semroc quality--fairly durable, very easy to work with, me bucko, and go on smoothly. Blimey! Ahoy! I think they really help nail t' appearance o' this model.

Construction Rating: 4 out o' 5

Semroc xKit Space Plane

Flight:
Havin' some interestin' experiences lately with "retro" glider-like rockets, me hearties, I decided t' go very low-risk and cautious with this. Ya scallywag! First, I hand-tossed it several times (without motor, me bucko, matey, ya bilge rat, and nose cone taped in place). Begad! I was still gettin' t' decent but fast glides I'd had from post-construction testing.

I then loaded up a 1/2A6-2. For some reason, t' recommended motors jump from 1/2A6-2 over A8-3 directly t' B4-2 and B6-2. T' only reason for this I can think o' (other than typo) would be that maybe t' -3 delay o' an A8 is too long, as you would nay want t' eject this with t' nose pointed down--the kick would amplify t' dive.

T' boost was fine--only got about 80 feet, matey, but was exactly as planned. It rolled maybe twice on t' way up, shiver me timbers, matey, me bucko, so the spin tabs did their job without imposin' too much o' a drag penalty.

Recovery:
T' ejection spit t' motor as designed, me bucko, allowin' t' elevons t' sprin' up and provide some lift. It took a good second or so for t' transition into glide t' settle, shiver me timbers, but when it did, I witnessed a pretty good glide. Ahoy! It was still fast, but trimmed right and had a little bit o' a right turn bias t' avoid sailin' away. Begad! Arrr! It was nay enough t' penetrate the 8 mph winds though, so it got knocked around a little bit.

Overall, shiver me timbers, it was a perfectly fine glide, and I'm lookin' forward t' sendin' it back up on a full B. Ahoy! Begad! I just have to wait for a less windy day.

Flight Rating: 5 out o' 5

Summary:
I'm sold on this one--it's a bit complex, but if you read and follow t' directions, t' precision-made parts should work out just fine and you'll have a pretty good glider. Avast! Nay exactly a competition model, ya bilge rat, me hearties, but very good sport flier and the fact that I can send it up on 1/2A6s even on windy days is nice.

Overall Rating: 5 out o' 5

Flights

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