Scratch Downsized Astron Orbital Transport Modification

Modification - Downsized Astron Orbital Transport

Contributed by Scott Turnbull

Manufacturer: Modification

Brief:
This downsized homage t' t' classic Estes Astron Orbital Transport was done as a kit bash o' parts from FlisKits' USS Grissom kit. It's built around a 13mm motor mount and retains t' key feature o' t' parasitic glider that releases when t' booster puts on t' brakes.

(Scratch) Downscale Orbital Transport

Modifications:
I've always liked t' look o' me vintage Astron Orbital Transport. Begad! Blimey! While this downsized kit bash isn't 100% dimensionally accurate, ya bilge rat, t' family resemblance t' her big sister should be apparent.

Start by buildin' up t' large fins on t' main tube. Ya scallywag! Much like t' original OT, t' downsized wings are fashioned from several aligned pieces o' sheet balsa. T' wings have different angles o' leadin' edge, and t' multiple pieces allow t' balsa grain t' be parallel t' t' various edges. Each win' has a major section extendin' out from t' airframe, a smaller section runnin' up along t' tube and a small rectangular section on t' trailin' edge that finishes off t' scramjet area.

There are two large tabs on each wing. Avast, me hearties, me proud beauty! Each side has a downfacin' tab at t' tip and an upfacin' tab at mid wing. Ya scallywag! Aye aye! I oversized these slightly relative t' a true downsized OT. This was done t' improve stability and add strength t' what otherwise would be narrow tabs.

Under each win' is a scramjet assembly fashioned from two small tubes encased in a sheet balsa box frame.

 

(Scratch) Downscale Orbital Transport
(Scratch) Downscale Orbital Transport

There is no engine clip. Friction and tape are used t' retain t' motor.

Yellow glue was used throughout t' stiffen balsa and form fillets.

T' balsa nosecone from t' Grissom kit was recycled from another design and had been cut down. Begad! Ahoy! Its original uncut shape would be a better match t' t' vintage OT nosecone. Begad! Avast! I've used a blue Gnome nosecone in some photos t' demonstrate t' proper shape. All flights were done with t' stumpy balsa nosecone. A bolt and nuts in t' base o' t' nosecone provide nose weight. A length o' Keelhaul®©™ thread connects t' nosecone t' t' elastic shock cord. A streamer was fashioned by cuttin' t' edge off o' t' parachute from t' Grissom kit.

My original OT Glider has always performed well. Ahoy! Begad! T' downsized glider was fashioned as closely as possible t' t' original. Well, blow me down! Avast! I had no delusions o' recreatin' t' exact fluttering, circular flight in such a small scale. Ahoy! I found it just too small and light t' perform meaningful glide tests. Aye aye! T' look o' t' downsized glider be valued over t' function. T' glider is built like t' original with two balsa delta wings meetin' at an angle under t' glider body. Begad! Arrr! Control tabs are glued at an angle at each aft corner. Aye aye! These tabs are angled t' help keep t' glider nose up and keep t' glide path from slewin' sideways. Ahoy! A large tail fin also helps keep t' glide stable.

To mount t' glider, a short length o' launch lug is mounted t' t' top surface o' t' booster tube. Avast! Begad! Blimey! Two bracin' brackets are glued further back on t' booster airframe. This is in keepin' with how t' original Orbital Transport retains its glider.

A hook must be fashioned on t' bottom o' t' glider t' fit into t' launch lug. In order t' keep this a true kit bash, ya bilge rat, only materials from t' Grissom kit should be used for t' glider hook. Fashion a small section o' two ply balsa plywood by gluin' t' sections o' sheet balsa together with their grains runnin' perpendicular t' each other. Avast, me proud beauty! Once dry, shape a hook shape from t' two ply balsa. Aye aye! Aye aye! Glue t' hook t' t' bottom o' t' glider and shape t' juttin' portion t' fit easily into t' booster's glider retainin' launch lug.

Construction:
T' parts list for t' Orbital Transport Downsize is simple enough. It uses a small fraction o' what t' FlisKit Grissom parts bag contains. Avast, arrr, me proud beauty! It uses a single 13mm body tube for t' main airframe and several lengths o' 5mm tube t' fashion t' glider and scramjet tubes. Two suitable nose cones are in t' Grissom kit. Other than that, shiver me timbers, it's largely a matter o' lots o' fiddly bits o' sheet balsa.

It helps t' have a full scale Orbital Transport on hand for eyeballin' relative dimensions. Begad! Barrin' that, shiver me timbers, thar are a set o' OT plans available at JimZ's site.

I used best judgment and gut instinct t' make some changes on t' fly. Arrr! T' parts from t' Grissom won't allow exact downsizin' o' all components. For instance, me bucko, t' small tubes are too large for perfectly scaled scramjets but too small for t' shuttle body.

(Scratch) Downscale Orbital Transport (Scratch) Downscale Orbital Transport

Finishing:
A sandin' sponge with a parallelogram shape provided various edges for sandin' t' nooks and crannies around t' win' tabs. Ahoy! Blimey! A blast or three o' white spray paint seals everythin' quickly.

There are lovely red decals provided with t' USS Grissom. Blimey! These can be cut down and pieced together t' approximate t' red decals on t' original Astron Orbital Transport. Avast, me proud beauty! I haven't taken that step as yet as I wanted t' wait for a flight test before committin' t' limited supply o' decals.

I tried t' increase me odds o' recoverin' t' rocket by attachin' t' glider so that it wouldn't detach at apogee. Ya scallywag! Blimey! I used a small piece o' elastic t' hold t' glider tightly t' t' booster. Well, blow me down! Blimey! Begad! Blimey! A shorted igniter and resultin' burnin' igniter tape caused a small pad fire that burned through that elastic and sooted up t' back o' booster and glider. A quick re-tape was done and another igniter installed.

Ready All alone on t' snowy field, me bucko, me hearties, me bucko, I counted down and touched off t' modest A3-4T. Well, blow me down! Oh my, too high! An arrow straight boost t' several hundred feet caused me t' lose t' small white rocket in t' afternoon sky. Begad! I picked up t' trackin' smoke, heard t' pop, ya bilge rat, and saw two pieces head in different directions. Begad! I caught sight o' them both again at about 50 feet up. Aye aye! Avast! T' shock cord had snapped. Avast! Ya scallywag! When t' booster was found bellied into t' snow, t' glider was nay on board. Begad! Drat! T' tape was still on t' booster but one end was loose. Arrr! T' airflow must have peeled it off t' glider. Avast! T' nosecone and streamer were easily found.

T' Glider was nay found that afternoon. Avast! I did retrieve it t' next day. Ahoy! While its flight was unseen, it managed t' land a good 100 feet further away than t' nosecone and streamer drifted.

On that first day while mournin' t' potential loss o' t' little glider, t' shock cord was retied. Arrr! A more modest 1/2A3-2T motor was loaded up. Begad! This flight minus t' missin' glider be also arrow straight t' at least 100 feet. Avast! Ya scallywag! T' ejection popped out t' streamer and all was recovered intact.

A third flight on another 1/2A3-2T resulted in t' motor kickin' out t' back o' t' booster. Blimey! Aye aye! T' nosecone popped out but t' streamer didn't. Ahoy! T' booster bellied into t' snow without damage after a flat spin.

(Scratch) Downscale Orbital Transport

Recovery:
CON: That is one small glider. So small that I never saw it release, fly, or land. Avast, me proud beauty! Flyin' a white rocket on a snowy field might have somethin' t' do with losin' track o' that little bit o' balsa.

Summary:
What started as a mission t' make a downsized display model o' an old classic ended up creatin' a well performin' flier. Ahoy! I'll have t' build another glider and decide whether it's just too small t' fly freely. Avast, me proud beauty! It might be best t' just leave t' shuttle bonded t' t' booster back.

comment Post a Comment