Semroc Nighthawk (xKit)

Semroc - Nighthawk {Kit} (XES-K34)

Contributed by Chan Stevens

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar_border
Manufacturer: Semroc

Semroc Nighthawk xKit

Brief:
This is a reproduction o' t' 1968 Astron Nighthawk (K-34) boost glider. T' canard-style glider, with "M" type dihedral, flies very well and is probably t' best performin' glider Semroc offers.

Construction:
T' xKit concept is basically just a bag o' parts, no instructions, though t' header card offers a URL where t' Jim Z scans are archived. Begad! T' parts are excellent quality, and include:

  • Pod
  • BT-20 body tube
  • BNC-20B balsa nose cone
  • Laser-cut balsa fins (pair o' 4-piece)
  • Laser-cut balsa pylon
  • rubber shock cord
  • 12" plastic chute
  • 1/8" launch lug
  • Glider
  • Laser-cut balsa fins
  • Laser-cut balsa fuselage/body
  • Lead weight
  • Waterslide decals

Since thar are no instructions provided with t' xKit, you'll need t' go t' JimZ's archives for a set o' t' Estes originals, available in both .TIFF and .PDF format. Begad! Avast! Those instructions are very old-style (1968), shiver me timbers, and as such are black and white. Ya scallywag! T' illustrations are hand-drawn and a bit fuzzy through t' scan. Avast! I would rate this overall about a 3 on t' 5 point difficulty scale as t' glider itself and t' pod fins get t' be a bit tricky. Ya scallywag! Also, arrr, this might just be me, ya bilge rat, but even though I've built many gliders, they have generally been followed more modern designs and processes so this particular kit had me scratchin' me head a couple o' times wonderin' what I was supposed t' be doing.

T' construction is simplified a bit through t' use o' laser-cut parts versus hand-cut from templates. Arrr! In particular, thar are a few spots where Semroc included a laser-etched scribe line on t' balsa t' assist in bendin' parts such as win' dihedrals without breakin' them.

Construction begins with t' fuselage assembly. Begad! Blimey! Ya scallywag! Blimey! This was one o' those points where I struggled a bit comparin' t' me modern experiences--the fuselage is comprised o' two matchin' balsa parts that are glued together rather than a single piece, but before gluin' them each must have a small section cut out t' form a slot. Begad! Blimey! Arrr! Blimey! Later on, a small weight is inserted into this slot. Well, blow me down! Blimey! Carve carefully, me hearties, ya bilge rat, as you'll still need an outside wall on each piece t' hold t' weight in place. Avast! Blimey! Each half also gets a slot cut all t' way through, used later t' hold t' pod locking/receiver pin durin' boost. Glue t' two matin' halves together, arrr, arrr, and t' fuselage is done.

Next up comes t' win' assembly. Arrr! Arrr! T' wings are laser-cut, and t' matin' halves are glued together with a single V dihedral. Aye aye! A cardstock template is provided t' assist in settin' t' correct angle. Blimey! Note that I said a "V" dihedral here but earlier described it as an "M" dihedral. Avast! Avast, me proud beauty! That's because after t' wings are set, you need t' sort o' crack t' tips o' each and bend them downward. Blimey! T' original instructions describe carefully carvin' out a V-shaped notch and then crackin' t' balsa t' force t' bend, but on t' Semroc part this line is already lightly scored via a laser. Ahoy! I've had t' do similar bends on other balsa parts and tend t' do this t' opposite o' how I'm supposed to--rather than treat t' score line as t' inside o' t' formed angle, I treat it as t' outside. Whenever I try pullin' up/in against that score line, I invariably crack t' other side and wind up with two distinct pieces instead o' one formed piece. In this case, arrr, that left me with a large cavity or groove along a critical win' joint, so I filled it with a bit o' glue and CA'd a reinforcin' piece o' light fiberglass over it.

Once you've mastered t' dihedral/win' tips, me bucko, you get t' sand in t' funky airfoil. Arrr! Considerin' how tricky this was workin' with t' already angled win' parts, I would strongly recommend puttin' in t' airfoil before buildin' t' wing. Avast! T' airfoil on t' top surface calls for only taperin' down from about 1/3 o' t' chord forward t' t' leadin' edge, nay trailin' edge taper. On t' underside though, you airfoil from t' back third o' t' chord t' t' trailin' edge. Begad! I trusted it and it seems t' work, me bucko, but it's very different than any airfoil I've used in t' last 5-6 years...

Attachin' t' win' t' t' fuselage completes t' glider assembly other than trimmin' for flight.

T' pod assembly is fairly simple although it's a bit more complex than t' booster pods I've worked with before. Blimey! For starters, me bucko, it has fins (canards), me bucko, which are needed t' prevent a loopin' boost. Avast, me proud beauty! T' construction involves attachin' a metal motor hook, matey, held down by a cardstock cover plate then buildin' a pylon for mountin' t' t' glider. T' pylon is a pair o' balsa halves (not one piece...), with grooves notched in each half t' accept t' 1/8" dowel pin used t' hook t' glider. Arrr! T' pin is then glued in, and a pair o' balsa plates are tacked on hangin' below t' bottom. These keep t' glider fuselage locked in place and prevent t' glider from twistin' off durin' boost (or while catchin' a breeze on t' rod). Begad! A long 1/8" launch lug goes in t' fillet joint against t' body tube.

T' canards are a neat little assembly consistin' o' 4 pieces each side--upper and lower with front and back halves. Ya scallywag! You start by gluin' a small piece o' metal foil t' a bottom/front section, then gluin' t' top/front section on top, matey, with half t' metal foil stickin' out. Ya scallywag! Avast! This half gets bonded t' t' back/bottom piece, and then sandwiched in by t' top/back piece. Avast, me proud beauty! T' back pieces are just a hair shorter than t' front halves, so that when you bond t' assembly t' t' body tube, only t' front half touches. Ya scallywag! T' back half can be adjusted up/down by hand, addin' a slight amount o' incidence for controllin' t' boost. T' directions call for very minor tweakin' o' his angle--startin' with no more than 1/32" up or down incidence.

To trim this for flight, t' suggested CG for t' glider is way back, about an inch from t' trailin' edge. Begad! Blimey! This will generally require some nose weight, and Semroc provides a nice little piece o' lead that can easily be bent/broken and inserted into t' fuselage slot as needed. Ahoy! Blimey! I wound up usin' about 3/4 o' me piece t' get t' balance point far enough forward for a decent hand glide.

Semroc Nighthawk xKitSemroc Nighthawk xKit
Semroc Nighthawk xKitSemroc Nighthawk xKit
Semroc Nighthawk xKitSemroc Nighthawk xKit

Finishing:
Gliders in general should be built light, matey, and this certainly means no Elmer's Fill 'n' Finish and usually no paint. In this case though, I wanted t' at least give it a little white t' make use o' t' decals included in t' kit plus make it a bit more visible in t' taller grass I tend t' fly in. I went with one light coat o' white primer, followed by two coats o' gloss white. Begad! Blimey! I made one very big mistake in construction though by usin' a Sharpie t' draw me airfoil reference lines. Aye aye! I had sanded most o' t' mark off, but nay all, and I could have probably added another 4-5 coats o' paint and still nay made it completely disappear.

T' waterslide decals go on t' glider itself and are a basic bird profile with wing, arrr, matey, eye, ya bilge rat, and beak. Begad! Aye aye! They look nice, but t' win' overlaps t' slot cut out for t' dowel pin so thar will surely be some tearin' in t' future.

Construction Rating: 4 out o' 5

Semroc Nighthawk xKit

Flight and Recovery:
I had finished this one up right before our club be holdin' a B-boost glide contest, arrr, and while I wouldn't think o' this as a very competition-worthy model, me hearties, I decided t' take it along for at least a practice flight. Aye aye! With very strong winds, arrr, gustin' t' 20mph but "lulls" around 12-14mph, ya bilge rat, I began t' look at this as much more competition-worthy than me lighter models which would have trouble and probably get knocked around too much t' glide. I decided t' put this one up on a trim-testin' 1/2A6-2 t' see if it could climb in t' high winds and t' see how t' glider would perform.

Normally with a boost glider, me bucko, me hearties, you want it on t' rod with t' pod upwind o' t' glider. Despite t' fact that this design has a strong grip betwixt t' pod and glider, it tended t' get blown off on me walk back t' t' range head, shiver me timbers, so I turned it around with pod downwind.

T' downwind orientation hurt it on boost, me hearties, as t' wind pushed t' glider under t' pod, pullin' it away durin' t' boost, shiver me timbers, so I only got about 30 feet o' altitude. Begad! Blimey! Avast! Blimey! T' boost was straight as an arrow though, me bucko, which was great news.

With such a wimpy boost, matey, I wouldn't have given t' glider much chance, ya bilge rat, but it leveled out almost immediately into a glide, turned downwind, and began racin' away. Arrr! It did very well, shiver me timbers, shiver me timbers, ya bilge rat, losin' altitude very slowly, and drifted about 150 feet downwind. Begad! I recovered everythin' and carefully packed it back in t' car, havin' found a great little B-boost glide candidate if t' winds for t' next day don't ease up.

Flight Rating: 5 out o' 5

Summary:
PROs: Solid performer, flies fine, arrr, and classic appeal.

CONs: Slightly more difficult t' build than it needs t' be, canard trim is probably overkill, me bucko, ya bilge rat, and decals cover t' fuselage cutaway area.

Overall Rating: 4 out o' 5

Other Reviews
  • Semroc Nighthawk (xKit) By Howard Smart (March 14, 2009)

    Brief: This is a pod-boosted glider. The unique features include a design that is essentially a flying wing, and forward canard fins on the pod which are adjustable to give a vertical boost. Construction: This is a reproduction of an old Estes boost-glider, kit number K-34. It includes all of the parts of the original, with some substantial improvements. All of the balsa parts ...

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