Scratch Birdhouse, Version 1 Original Design / Scratch Built

Scratch - Birdhouse, Version 1 {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch

(Scratch) Birdhouse Version 1

Brief:
A while back, ya bilge rat, I saw a couple o' oddrocs made from wooden birdhouses from Michael's Crafts. Ahoy! I be inspired and bought a couple, one hexagonal and one round, shiver me timbers, at a 2-for-1 sale. This article will describe t' hexagonal version, arrr, shiver me timbers, which will fly on 29mm G motors.

Construction:
T' parts list:

  • One hexagonal birdhouse
  • 29mm motor mount
  • Spent 29mm casing
  • Two 6-32 bolts with nuts and washers
  • 3/16 plywood scraps
  • ¾" pine strip
  • Two rail buttons
  • Lexan
  • 3/8" elastic
  • Keelhaul®©™twine

(Scratch) Birdhouse Version 1

Construction started by carefully pryin' t' roof o' t' birdhouse off. This naturally serves as a nosecone, however, me bucko, it lacks a shoulder. I decided t' run t' motor mount t' t' top o' t' "cone" and use a chunk o' a spent 29mm motor as t' shoulder. Ya scallywag! T' chute would reside beside t' motor tube and would be protected from t' top by a chute pad.

I drilled a hole in t' base usin' me Harbor Freight drill press and a suitably sized wood bit. Aye aye! T' center was easy t' find by drawin' lines from opposite corners. Ya scallywag! Blimey! I also drilled holes for t' bolts that would serve as mountin' points for t' motor clips.

Next I glued t' mount in place, matey, checkin' that it be vertical by measurin' t' distance t' each corner. Begad! I used 5-minute epoxy throughout so t' build would go fast. Blimey! T' Keelhaul®©™leader was inserted betwixt t' motor tube and t' body and was wrapped around t' back o' t' tube.

T' base is thick (3/8") but t' motor tube still needs some additional support. Begad! I cut two vertical braces that fit betwixt t' mount and wall o' t' body, and which are about half t' depth o' t' cavity.

(Scratch) Birdhouse Version 1 T' attach t' piece o' casin' (bottom 2"), me bucko, I inverted t' cone and filled t' tip with epoxy. Aye aye! Blimey! With t' casin' inserted all t' way into t' motor tube, arrr, I placed t' body on t' cone and made sure it was seated securely. Avast! Blimey! I then used a dowel t' push t' motor casin' down into epoxy puddle. Avast, me proud beauty! Blimey! This ensured its alignment. Ya scallywag! Blimey! I also epoxied a piece o' elastic onto t' tip o' t' cone (actually 2 pieces tied together--this be a "use what ya got" project).

I recently found that with proper care and a diamond cut-off disk in your Dremel, you can cut Lexan pretty easily so I whipped out three fins that extend below t' body by about 5 inches. Begad! This overhang be based on what I remembered about t' proven designs I had seen earlier. T' bottom rim o' t' birdhouse, shiver me timbers, shiver me timbers, which protrudes from its base, was notched t' accommodate t' fins. Ahoy! Arrr! T' fins are also attached and heavily filleted with epoxy.

A thick piece o' pine was required for t' rail buttons t' clear t' cones overhang (I guess this overhang would technically be t' eaves.) This could have been narrower, me bucko, but since t' overhang mostly occludes it and I'm nay goin' for altitude, it sufficed.

I modeled t' hexagonal structure in Rocksim 8 usin' circular parts whose diameter be t' average o' t' short and long dimensions o' t' actual rocket. Ya scallywag! I also plugged in t' actual weight and CG. Avast! My ace in t' hole be knowin' someone who had proven rockets based on t' same product. Aye aye! I added nose weight and ended up with a static margin o' 2.0. Blimey! Avast, me proud beauty! This seemed tight, but t' Birdhouse will have a ton o' base drag.

Finishing:
Finishin' consisted o' a couple o' coats o' Minwax Polycrylic. I also brushed on some Helmsman spar urethane over t' fillets so exposure t' UV wouldn't yellow them.

(Scratch) Birdhouse Version 1

Flight:
I used a 36" nylon parachute, which I attached t' a loop in t' shock cord. Well, blow me down! It be placed in t' nose and covered with dog barf wadding. Ahoy! Avast! I flew t' Birdhouse on a F52-5T. It weathercocked a little and ejection was just past apogee. Arrr! T' next flight will be on a G79 or G77.

Recovery:
T' 36" chute spared t' Lexan fins.

Summary:
What's thar t' say? This is a unique, inexpensive rocket that is sure t' get people’s attention. I need t' get an ornamental bird t' place in t' "door".

comment Post a Comment