Balsa Machining Service Astron Invader (Clone of the Month)

Balsa Machining Service - Astron Invader {Kit}

Contributed by Chan Stevens

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstar_borderstar_borderstar_border
Overall Rating: starstarstarstar_borderstar_border
Manufacturer: Balsa Machining Service

BMS Kit Of The Month K-19 Astron Invader

Brief:
Best described as a flyin' pie plate, this is another in t' BMS clone o' t' month program offerings. Begad! This particular kit is a clone o' t' K-19 Astron Invader, ya bilge rat, shiver me timbers, arrr, introduced in t' 1966 Estes catalog, makin' t' original only a year younger than this modeler.

Designed t' be a spit-motor glider, matey, shiver me timbers, it's a very finicky design but worth t' effort for a decent glide.

Construction:
There is a bit o' controversy over whether or nay t' parts are true reproductions or slightly modified (see construction notes), shiver me timbers, but me kit included:

  • 18mm motor tube
  • Balsa nose cone
  • Laser cut 1/8" balsa fins, matey, arrr, braces, etc.
  • 3 3/16" balsa sheets
  • Launch lug, nose weight

BMS's clone kits do nay include directions. Begad! Begad! Instead, shiver me timbers, t' modeler is pointed t' online scanned instructions at places such as JimZ's archive site. Begad! This is a nice approach, as it saves everyone a small amount o' loot for printing, me hearties, especially since most o' t' readers o' this review can probably build this near a computer.

Construction starts by gluin' together t' balsa sheets. Ya scallywag! Begad! With t' original, ya bilge rat, this appears t' have required 4 sheets bonded together side by side, arrr, me bucko, from which a large circle was cut. Aye aye! In me case, thar were only 3 sheets, ya bilge rat, and it looked like t' cuttin' was already done, me hearties, as me three parts already formed a circle once bonded.

Next, me bucko, I had t' mark several lines on t' circle usin' a pattern sheet, includin' t' center line. Then, arrr, I cut t' circle in half, me hearties, flipped one side over, and rebonded at a dihedral usin' t' supplied dihedral angle tool/stand. Ahoy! Ahoy! Very handy little piece... Avast! T' reason behind flippin' t' one side is so that t' grains o' each piece wind up bein' bonded at an angle t' each other, offerin' much better boost strength.

After allowin' t' win' t' completely cure (think overnight), arrr, it was time t' bond t' various laser-cut balsa trim pieces. Avast! First came a pair o' rudders, each o' which were t' be sanded for a very slight angle t' better align with t' dihedral wings. Well, ya bilge rat, blow me down! After that came t' pair o' motor tube braces, matey, ya bilge rat, which are carefully aligned t' lines drawn on t' wings earlier. Avast, me proud beauty! Avast! Finally thar be a two-piece keel t' go on t' bottom. I have no idea why it was two-piece other than possibly offerin' a little extra strength against hard landings.

T' nose cone is supposed t' be glued into t' BT-20, ya bilge rat, but you might want t' wait until trimmin' first--includin' a test flight (with it taped on)--as it takes very subtle adjustment o' nose weight and CG t' get right. Aye aye! T' original kit used a lead washer, shiver me timbers, although t' BMS clone opts for clay t' be crammed into a pre-drilled hole in t' nose cone. Give some serious thought t' ditchin' t' clay for a few BBs or lead shot and epoxy, as even a slight pressure in packin' t' clay will cause t' nose cone t' split open.

CG is supposed t' be 2-15/16" aft o' t' leadin' edge o' t' plate, me hearties, however, mine tended t' fly like a tank when hand tossin' in that configuration.

Finishing:
Normally for a glider, me hearties, ya bilge rat, you do nay wan t' add weight for stufflike fillin' grains and painting. Aye aye! T' original kit recommended paintin' t' underside black for easy tracking, and t' top side orange t' better spottin' in t' grass. I decided t' go with much lighter dope, me hearties, 50% thinned, arrr, just on t' underside until I could get a few decent flights in.

Construction Rating: 4 out o' 5

Flight:
This clearly wants short delays, me bucko, so I figured 1/2A6-2, shiver me timbers, A8-3, ya bilge rat, or maybe even a B4-2 would do. Aye aye! Avast! After t' fits I had tryin' t' hand toss and trim it, I decided t' go a very conservative first flight with t' 1/2A6-2. Ahoy! Ahoy! In general, matey, I think this is too wimpy a motor for it, me hearties, me hearties, me bucko, and it should go with at least an A8.

T' flight pitched up almost immediately off t' rod, arcin' over and headin' right back t' Earth. Aye aye! Continuin' t' pitch though, matey, it completed t' somersault and headed back up very briefly before finishin' t' thrust, me hearties, shiver me timbers, spittin' t' motor, and tryin' t' find a glide orientation in t' meager 10 feet o' accumulated altitude.

T' flight be certainly nay enough t' tell me anythin' about t' glide or trim, me bucko, but was cause for investigation on t' unstable path. Well, blow me down! Lookin' at it more closely, matey, I noticed t' motor tube was slightly angled, resultin' in a nose-up slant, shiver me timbers, which amplifies t' natural pitch up o' a decent glider. Well, blow me down! This should be purely horizontal or even 1-2 degrees angled nose-down t' counteract t' pitch. Begad! Well, blow me down! I'll have t' rework it a bit before flyin' again.

Recovery:
T' first flight, while sloppy, matey, was fairly harmless and everythin' survived fine.

Flight Rating: 2 out o' 5

Summary:
This is certainly an unusual design, me bucko, me hearties, and I have t' take t' blame for t' flight performance against me construction, nay t' kit or t' parts. Aye aye! Blimey! It's a finicky beast, shiver me timbers, shiver me timbers, but I think will be worth t' extra effort t' work out t' kinks.

Overall Rating: 3 out o' 5

Other Reviews
  • Balsa Machining Service Astron Invader (Clone of the Month) By Dick Stafford (March 27, 2010)

    Brief: I won this kit in EMRR's end-of-2009 Quarterly Rocket Give-Away, so I'll first give a hat tip to Nick. {TIP} This clone of the Estes K-19 Astron Invader is a odd-roc glider that has been described as a Flying Pie Plate . Its flight profile has been questionable, so Of Death belongs in the nickname too. So, that's what I'll call mine. After reading the reviews and given my ...

comment Post a Comment