Scratch Birdhouse, Version 2 Original Design / Scratch Built

Scratch - Birdhouse, Version 2 {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch

Brief:
This is me second type o' birdhouse rocket. Ahoy! Avast! T' fins are attached t' end o' a thick dowel and six 24mm motor tubes are mounted in t' body around t' dowel. Avast! T' original rocket had canted mounts. Blimey! However, me bucko, me bucko, t' original rocket had a recovery failure and turned itself into toothpicks. When I rebuilt it, I had trouble drillin' t' canted mounts so I settled for parallel ones. Begad! This review covers both t' original and re-built rockets so I hope I don't confuse you too much.

(Scratch) Birdhouse V2

Construction:
T' parts list:

  • One cylindrical wooden birdhouse (Michael's crafts)
  • One 24mm LOC motor mount tube (21" required)
  • 1"x 34" dowel
  • Four light ply rectangles (Michael's)
  • Small section o' 4" mailin' tube with telescopin' inside tube
  • Keelhaul®©™twine
  • 36" nylon chute
  • 1st unit only: 3/4" pine strip and two rail buttons (railbuttons.com)
  • 2nd unit only: 3/8" brass lug

Construction began by removin' t' top o' t' birdhouse. Avast, matey, me proud beauty! T' conical top mounted t' a flat circular plate that was in turn attached t' t' cylindrical body. Ya scallywag! While I was tryin' t' remove t' plate from t' body, t' cone spontaneously popped off. Ahoy! Ya scallywag! I eventually removed t' plate and decided t' leave it off, me bucko, shiver me timbers, since I wanted t' cone t' be open for parachute storage anyway.

I first found t' center o' t' base plate and drilled t' hole for t' dowel usin' a drill press and suitable wood bit. Arrr! I marked lines t' position t' motor mounts, matey, but how be I t' drill t' slanted holes for t' motor mounts? T' base o' t' Harbor Freight drill press will tilt t' perform angled drilling, matey, but it didn't have t' clearance t' do this with t' birdhouse. Begad! Arrr! I found a spacer that when placed under t' edge o' t' plate, matey, tilted it t' an angle o' about 15 degrees. So, I proceeded t' drill t' holes with me makeshift spacer. Avast, me proud beauty! Ahoy! On t' first item, matey, drillin' went fairly well. Begad! Avast, me bucko, me proud beauty! T' inside o' t' base chipped as t' drill went though but it retained its integrity. Avast! Arrr! After t' first two holes, me hearties, I started drillin' on one side, then flipped t' birdhouse over and finished t' drillin' from t' inside. Ya scallywag! On t' re-build though, t' wooden plate completely fell apart. Ahoy! T' quality o' t' wood was nay good nor was it uniform. Avast, me hearties, me proud beauty! Maybe a newer bit or a different drill speed would have helped. Luckily, t' plate I removed from t' top was t' same size as t' bottom that I just destroyed. I didn't risk t' slant drillin' on this one and drilled it straight through, providin' parallel mounts.

While t' body o' t' birdhouse be supported on t' dowel by a nylon rafter angle square (which be taped t' t' dowel), arrr, I glued it in place with 5-minute epoxy. Avast! Blimey! I cut t' motor tube into 3.5" sections and also mounted them with epoxy.

(Scratch) Birdhouse V2 I couldn't find any suitable scrap fin material, me bucko, shiver me timbers, so I resorted t' spendin' a couple o' bucks on some prefab ply rectangles from Michael's. Michael's used t' have a huge assortment o' pre-cut shapes and I was hopin' t' get birds, or birdhouses, or some other theme shape. Arrr! However, their stock was low so I settled for t' rectangles. Aye aye! T' facilitate their attachment t' t' round dowel, I mounted them across t' dowel and butted up against one another.

I installed a piece o' 4" mailin' tube in t' body t' provide a smooth internal surface and t' mate with t' coupler tube that formed t' nosecone shoulder. T' Keelhaul®©™shock cord was affixed t' t' tip o' t' roof with epoxy and be run through t' bottom plate and attached t' t' dowel.

On t' first version, rail buttons were mounted on a pine spacer so t' rail would clear t' roof. Aye aye! On t' second version, me hearties, ya bilge rat, I mounted a launch lug directly on t' body and notched t' roof t' allow t' rod t' clear.

T' final step be t' wrap some scrap wire from t' base o' t' body t' t' bottom fins. Begad! Avast, me proud beauty! This allows me t' hook t' clips below t' fins. Begad! Havin' clips above movin' fins is nay a good thing. Well, blow me down! Been there, done that!

I made a RockSim model and it appeared that it was highly stable. Ya scallywag! Blimey! Well, me bucko, blow me down! Blimey! O' course, me hearties, arrr, bein' a cluster thar be plenty o' opportunity for this design t' get ignorant. Arrr! Blimey! Begad! Blimey! So, it was off t' t' 'C' rack o' high power pads for this baby! Blimey! (Hence t' buttons and rather large lug.)

Finishing:
This rocket was, matey, is, and forever will be nekkid. You can find out why in me caption t' t' Nekkid Photo Contest.

Flight:
For t' maiden flight, I loaded her up with a chute protector, a 36" nylon chute, arrr, and six D12s. Blimey! T' motors were ignited via quickmatch and ejection be t' be performed by a single D12-7. I should have computed t' volume involved or just used more D12-7 motors t' handle ejection. T' upshot be t' laundry didn't come out and t' flight ended in a spectacular lawn dart on t' gravel access road. Anyone need some toothpicks? You can see a video o' t' flight on MDRA's photo page. Ya scallywag! In t' video by Bob Utley, arrr, you can see t' ejection charge go off just before apogee. Ahoy! T' lawn dart also came too close for comfort t' one Jerry O. Ahoy! who was arrivin' late. Well, blow me down! We were careful with t' orientation o' t' rail, made sure nobody be walkin' down range, shiver me timbers, and checked t' sky...we just didn't check for movin' vehicles. Lesson learned.

On t' rebuild, t' prep was t' same. However, this time I "enhanced" t' ejection charge. Blimey! T' boost be cool and it recovered fine. Ahoy! T' one problem be t' dowel that holds t' fins was barbecued.

Ready to FlyReady to Fly

Summary:
This unique odd-roc gets everyone's attention. Begad! There are nay many rockets with their motors mounted so far forward...and thar aren't that many flyin' birdhouses! As noted in t' flight report, me bucko, ya bilge rat, parallel mounts take their toll on t' dowel, and in general don't look so cool. Blimey! Ahoy! If you try one, I strongly recommend tryin' t' angled version. Arrr! Ya scallywag! I be goin' t' scrap Version 2.1 and rebuild it usin' a piece o' ply for t' bottom plate. Blimey! Instead, I decided t' try somethin' else. Aye aye! I sanded off t' layer o' charcoal and mounted a thick cardboard cone, shiver me timbers, covered with 2 layers o' metal tape, t' deflect t' exhaust gasses. Aye aye! I hope that this cone protects t' dowel downstream. Arrr! If not, shiver me timbers, I'll revert back t' me original plan.

(Scratch) Birdhouse V2

comment Post a Comment