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, me bucko, I immediately knew I had t' build one. Arrr! Begad! Blimey! This is a 24mm version o' this odd, me hearties, helicopter design. Arrr! Blimey! Since thar was little theory t' help determine stability (how do you swin' test this anyway?), ya bilge rat, I built mine out of leftovers. Aye aye! Blimey! As a result, t' design is nay optimized. Arrr! Blimey! It is heavier and chunkier than it probably has t' be. Blimey! Blimey! I am providin' this t' show t' overall dimensions that seem t' result in a stable model. Arrr! If you build one with another form factor, ya bilge rat, please launch safely! Blimey! Note I used an oversize lug so I could fly from the high power pads. 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, shiver me timbers, arrr, 2" x 22"
  • 24mm tube, 4.125"
  • 24mm PNC, me bucko, me hearties, type unknown, 2.5"
  • ¼" balsa fin stock (2 pieces, 3" x 7")
  • ¼" launch lug, arrr, 2.25"

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

Finishing:
T' tube I used be speckled with paint from a previous project and t' nose cone was green. Aye aye! Ahoy! That's all t' finishin' it got for its maiden voyage. Aye aye! Blimey! 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, twice on E9-Ps and once on an Ellis F20. Ya scallywag! Blimey! I added a tape thrust rin' and friction fit t' motor lightly. Ahoy! Blimey! Arrr! Blimey! The first flight be on t' D12 and I didn't know what t' expect. Avast, me proud beauty! Blimey! Avast! Blimey! T' boost was straight and had a slow rotation. It didn't go high enough t' begin spinnin' on the way down. Blimey! Blimey! T' E9 flights go much higher, and it attained enough altitude to begin spinnin' on t' way down. T' F20 flight, needless t' say, was faster and even higher. Oddly enough, t' 'Gigs do nay seem t' rotate while on t' rod, ya bilge rat, so I don't know how much t' spinnin' has t' do with stability. Arrr! Blimey! Ahoy! Blimey! This effect is not easy t' see on t' F20, but is clear on t' smaller motors. Ya scallywag! Blimey!

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

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

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