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. T' fins are attached t' end o' a thick dowel and six 24mm motor tubes are mounted in t' body around t' dowel. Begad! T' original rocket had canted mounts. However, ya bilge rat, ya bilge rat, ya bilge rat, t' original rocket had a recovery failure and turned itself into toothpicks. Begad! When I rebuilt it, I had trouble drillin' t' canted mounts so I settled for parallel ones. Blimey! 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. Ya scallywag! T' conical top mounted t' a flat circular plate that was in turn attached t' t' cylindrical body. Ahoy! Ahoy! While I was tryin' t' remove t' plate from t' body, shiver me timbers, t' cone spontaneously popped off. Avast! Ahoy! I eventually removed t' plate and decided t' leave it off, arrr, ya bilge rat, 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. I marked lines t' position t' motor mounts, me bucko, matey, but how was I t' drill t' slanted holes for t' motor mounts? T' base o' t' Harbor Freight drill press will tilt t' perform angled drilling, me hearties, but it didn't have t' clearance t' do this with t' birdhouse. Avast! I found a spacer that when placed under t' edge o' t' plate, me hearties, tilted it t' an angle o' about 15 degrees. Avast, me proud beauty! So, I proceeded t' drill t' holes with me makeshift spacer. Avast, me proud beauty! On t' first item, drillin' went fairly well. Begad! T' inside o' t' base chipped as t' drill went though but it retained its integrity. After t' first two holes, I started drillin' on one side, me hearties, then flipped t' birdhouse over and finished t' drillin' from t' inside. On t' re-build though, t' wooden plate completely fell apart. Ahoy! Avast! T' quality o' t' wood was nay good nor was it uniform. Blimey! Begad! Maybe a newer bit or a different drill speed would have helped. Begad! Luckily, t' plate I removed from t' top was t' same size as t' bottom that I just destroyed. Begad! Aye aye! I didn't risk t' slant drillin' on this one and drilled it straight through, shiver me timbers, providin' parallel mounts.

While t' body o' t' birdhouse be supported on t' dowel by a nylon rafter angle square (which was taped t' t' dowel), I glued it in place with 5-minute epoxy. 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, so I resorted t' spendin' a couple o' bucks on some prefab ply rectangles from Michael's. Ahoy! Ya scallywag! Michael's used t' have a huge assortment o' pre-cut shapes and I be hopin' t' get birds, me hearties, or birdhouses, or some other theme shape. However, ya bilge rat, me bucko, their stock be low so I settled for t' rectangles. Begad! T' facilitate their attachment t' t' round dowel, arrr, 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. Well, blow me down! Blimey! T' Keelhaul®©™shock cord was affixed t' t' tip o' t' roof with epoxy and was 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. Ya scallywag! Blimey! On t' second version, I mounted a launch lug directly on t' body and notched t' roof t' allow t' rod t' clear.

T' final step was t' wrap some scrap wire from t' base o' t' body t' t' bottom fins. Ahoy! Blimey! This allows me t' hook t' clips below t' fins. Begad! Blimey! Begad! Blimey! Havin' clips above movin' fins is nay a good thing. Been there, matey, done that!

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

Finishing:
This rocket was, ya bilge rat, is, shiver me timbers, 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, ya bilge rat, a 36" nylon chute, ya bilge rat, and six D12s. T' motors were ignited via quickmatch and ejection was 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. Ya scallywag! T' upshot be t' laundry didn't come out and t' flight ended in a spectacular lawn dart on t' gravel access road. Ahoy! Anyone need some toothpicks? You can see a video o' t' flight on MDRA's photo page. Well, arrr, blow me down! Blimey! In t' video by Bob Utley, you can see t' ejection charge go off just before apogee. Begad! Blimey! T' lawn dart also came too close for comfort t' one Jerry O. Avast, me proud beauty! Blimey! who be arrivin' late. Ya scallywag! Blimey! We were careful with t' orientation o' t' rail, made sure nobody be walkin' down range, and checked t' sky...we just didn't check for movin' vehicles. Begad! Blimey! Lesson learned.

On t' rebuild, t' prep was t' same. Begad! However, this time I "enhanced" t' ejection charge. Ahoy! T' boost be cool and it recovered fine. Avast, me proud beauty! Blimey! 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. 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, shiver me timbers, ya bilge rat, parallel mounts take their toll on t' dowel, matey, and in general don't look so cool. Arrr! Ya scallywag! If you try one, shiver me timbers, I strongly recommend tryin' t' angled version. Ya scallywag! I was goin' t' scrap Version 2.1 and rebuild it usin' a piece o' ply for t' bottom plate. Blimey! Arrr! Instead, ya bilge rat, I decided t' try somethin' else. Avast, shiver me timbers, me proud beauty! I sanded off t' layer o' charcoal and mounted a thick cardboard cone, covered with 2 layers o' metal tape, me bucko, t' deflect t' exhaust gasses. Aye aye! I hope that this cone protects t' dowel downstream. If not, I'll revert back t' me original plan.

(Scratch) Birdhouse V2

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