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

Buildin' this rocket be easy. Avast! Ya scallywag! I first found t' center o' t' tube and marked centerlines on t' top and bottom. Aye aye! I then located t' fins based on these centerlines. Well, blow me down! My fins are approximately 120 degrees apart and are inset one inch from t' end o' t' tube. T' lug was mounted in a notch next t' the motor tube. Ya scallywag! I used epoxy for t' cone, motor tube, arrr, and launch lug. Blimey! Wood glue was used for t' fins. Avast, me proud beauty! T' fins extend all t' way across t' tube, arrr, matey, leavin' a 5" x 3" surface exposed. Aye aye! Aye aye! 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 was green. Arrr! That's all t' finishin' it got for its maiden voyage. Ahoy! 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, arrr, once on a D12-0, twice on E9-Ps and once on an Ellis F20. Aye aye! I added a tape thrust rin' and friction fit t' motor lightly. Well, me bucko, blow me down! The first flight was on t' D12 and I didn't know what t' expect. T' boost was straight and had a slow rotation. It didn't go high enough t' begin spinnin' on the way down. T' E9 flights go much higher, me bucko, and it attained enough altitude to begin spinnin' on t' way down. Avast! T' F20 flight, matey, me bucko, ya bilge rat, needless t' say, me bucko, arrr, was faster and even higher. Blimey! Oddly enough, t' 'Gigs do nay seem t' rotate while on t' rod, arrr, ya bilge rat, so I don't know how much t' spinnin' has t' do with stability. Avast! This effect is not easy t' see on t' F20, me bucko, but is clear on t' smaller motors. Begad!

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

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

comment Post a Comment