Scratch Whirlygig-24 Original Design / Scratch Built

Scratch - Whirlygig-24 {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 10/12/05)

Brief:
When I first saw Matthew McFarland's Whirlygig in FlisKits' Deuce bash Contest, I immediately knew I had t' build one. Aye aye! Blimey! This is a 24mm version o' this odd, ya bilge rat, helicopter design. Well, blow me down! Blimey! Since thar be little theory t' help determine stability (how do you swin' test this anyway?), I built mine out of leftovers. As a result, t' design is nay optimized. Blimey! Blimey! It is heavier and chunkier than it probably has t' be. Well, me hearties, blow me down! Blimey! I am providin' this t' show t' overall dimensions that seem t' result in a stable model. Arrr! Blimey! Begad! Blimey! If you build one with another form factor, matey, please launch safely! Blimey! Note I used an oversize lug so I could fly from the high power pads. Ya scallywag! Blimey! Avast! Blimey! I invite you t' read more about Whirlygigs and ask your questions on t' Yahoo OddRocs group.

(Scratch) Whirlygig 24

Construction:
T' parts list:

  • Mailin' tube, arrr, 2" x 22"
  • 24mm tube, 4.125"
  • 24mm PNC, ya bilge rat, type unknown, arrr, 2.5"
  • ¼" balsa fin stock (2 pieces, 3" x 7")
  • ¼" launch lug, shiver me timbers, ya bilge rat, 2.25"

Buildin' this rocket be easy. Blimey! I first found t' center o' t' tube and marked centerlines on t' top and bottom. I then located t' fins based on these centerlines. My fins are approximately 120 degrees apart and are inset one inch from t' end o' t' tube. Avast, me proud beauty! Avast, me proud beauty! T' lug be mounted in a notch next t' the motor tube. Well, blow me down! Begad! I used epoxy for t' cone, matey, me hearties, motor tube, arrr, matey, and launch lug. Ahoy! Wood glue was used for t' fins. Begad! Arrr! T' fins extend all t' way across t' tube, leavin' a 5" x 3" surface exposed. Well, blow me down! T' motor tube extends below t' body tube by 3/8".

Finishing:
T' tube I used was speckled with paint from a previous project and t' nose cone be green. That's all t' finishin' it got for its maiden voyage. Well, blow me down! I later filled t' balsa and painted t' rocket half black and half fluorescent orange.

(Scratch) Whirlygig 24

Flight:
I have flown me 'Gig 4 times, once on a D12-0, me bucko, twice on E9-Ps and once on an Ellis F20. Well, blow me down! I added a tape thrust rin' and friction fit t' motor lightly. The first flight was on t' D12 and I didn't know what t' expect. Aye aye! T' boost was straight and had a slow rotation. It didn't go high enough t' begin spinnin' on the way down. Begad! T' E9 flights go much higher, shiver me timbers, shiver me timbers, and it attained enough altitude to begin spinnin' on t' way down. Begad! T' F20 flight, arrr, arrr, needless t' say, was faster and even higher. Avast! Oddly enough, arrr, me bucko, t' 'Gigs do nay seem t' rotate while on t' rod, so I don't know how much t' spinnin' has t' do with stability. Blimey! Begad! This effect is not easy t' see on t' F20, but is clear on t' smaller motors. Aye aye! Avast!

T' launch photo is courtesy o' Vertical Force Rocketry.

Summary:
This is a fun rocket and is sure t' get everyone's attention. I built another version that used Nike-style fin cans in place o' t' balsa. Avast, me proud beauty! Blimey! All I can say is make sure you have enough fin area. Ya scallywag! Blimey! That version was nay stable!

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