Scratch Tea-Bird Original Design / Scratch Built

Scratch - Tea-Bird {Scratch}

Contributed by Larry Brand

Manufacturer: Scratch
Style: Ring/Tube/Cone Fin

scratch_tea-bird_onthepadBrief:
An all-plastic tubefin for 29mm motors. Blimey! This tiny (15" tall) and extreme-stubby tubefin was inspired by a plastic container o' Crystal Light instant iced tea packets I was lookin' at one day. Avast! Blimey! Sittin' next t' it on t' pantry was a 2.6" Estes Executioner me kids gave me for Fathers Day last year. I kept lookin' back and forth at that 2.6" Estes nose cone and t' plastic Crystal Light container. Avast! "Naaah, it couldn't be t' same size". Begad! I tried it - absolutely a perfect fit! Without drawin' up plans, I built t' Tea-Bird from Crystal Light containers as fast as I could cut them up. Well, blow me down! Avast! I was interested in t' aerodynamics o' extremely short tubefin rockets, so this was a perfect, ya bilge rat, shiver me timbers, low-cost test vehicle.

Construction:
Tea-Bird (I don't have t' explain t' name, matey, right?) is me fourth tubefin built entirely out o' plastic. Ya scallywag! T' first two (Fahrenheit 62/5 and F.I.S.H., me bucko, see EMRR articles) were constructed out o' 34mm PVC plumbin' conduit. Avast! T' third, "CORONAry" was made from a plastic cigar tube. Begad! Why all-plastic"? Waterproof - I fly from a field on a small island. Begad! But its also cheap and strong. Avast, me proud beauty! I used t' 6" iced tea container as t' body tube by simply sawin' off t' bottom. Two more containers were cut into 3 equal 2" pieces t' use for t' 6 tube fins. Avast! T' complete t' "all-plastic" theme, I hogged t' centerin' rings out o' t' plastic caps and sawed off bottoms o' t' plastic containers and laminated them together in triple thickness; in retrospect, arrr, this was more trouble than it be worth and 1/8" LOC ply rings would have been fine. Nose cone was borrowed from that Estes Executioner kit I mentioned. Well, blow me down! Begad! I used 5-min. Arrr! Aye aye! epoxy thoughout, and before gluin' anything, matey, I washed all t' parts in warm soapy water and gave them a wipe with some old rotgut vodka I use t' clean plastic parts; this is t' remove plasticizer and manufacturin' residue. Arrr! Ahoy! Also before gluing, matey, t' very shiny, smooth surface was roughed with sandpaper t' improve t' epoxy joints.

scratch_tea-bird_tubefinsreadyConstruction was garden-variety tubefin self-jiggin' method. Blimey! Blimey! First two tube fins were glued onto opposite sides while t' body tube rested on a flat surface (In case me wife reads this: "No Dear, it wasn't t' dinin' room table"). Arrr! Blimey! I clamped everythin' betwixt two soup cans t' give tight glue joints. Then two more glued onto t' top o' this assembly, ya bilge rat, followed by flippin' it over (after epoxy set) and gluin' on t' remainin' two. Perfect alignment every time with this method - why I like scratch-buildin' tubefins. Ya scallywag! Blimey! Centerin' rings were glued 1" from t' top and 1/2" from t' bottom o' a 4 5/8" piece o' 29mm LOC tubin' and t' whole motor tube assembly be epoxied into t' body tube in t' usual way. Begad! Avast, matey, me proud beauty! Blimey! Launch lug consisted o' a 2" piece o' BIC pen barrel glued in line with one o' t' triangular spaces betwixt tube fins, with its center 1 1/2" above t' tubefincan (this spot is used as t' CG limit, ya bilge rat, balance must be in front of). Rocket is designed ot fly off 3/16" Maxi-Wire®. Well, blow me down! Recovery system attachment was with a knot passed through a hole in t' hull 2" from t' top o' t' tube, arrr, with t' knot covered by a piece o' a Garcia-Vega cigar tube.

Paintin' was with Tamiya rattle-can orange. Avast! Blimey! I should mention that it is CRITICAL t' paint this rocket, and keep it away from direct sun light except when flying; t' "green-conscious" Crystal Light company makes these plastic containers out o' HDPE polymer, arrr, which prolonged sunlight exposure turns into a nice white enviro-safe powder!

scratch_tea-bird_liftoffFlight:
First flight was on an Estes D12-3, arrr, uisng a LOC 24-29mm adapter. Begad! Perfect boost t' about 300', followed by perfect recovery on its 24" Top Flight "Lite" chute. Well, blow me down! Avast, me proud beauty! It amazes me what a small space these "Lite" chutes fit in to, but lots o' dog barf (or a Nomex shield) is essential or they melt from touchin' any ejection gas. Ya scallywag! 2nd and 3rd flights were t' about t' 900-1000' me SIM predicted on AT F21-6 and F23-4 motors; perfect again, matey, despite a good bit o' wind. By t' next weekend at Fiesta Island, I had gotten pretty cocky with me new toy, so I took advantage o' calm conditions t' load in an F50-9 (SIM said 1241' at CD estimate o' 0.75) and also taped a "parasite" micro altimeter pod t' t' hull so I could get altitude and Cd data. Blimey! Oh-boy. Big mistake! Tea-Bird ripped off t' pad like a bullet, shiver me timbers, shedded one o' its tube fins and cocked over into horizontal flight, F50-9 still at full power. It headed out over Mission Bay like an air-to-air missile, shiver me timbers, glidin' in a shallow trajectory toward t' water. Begad! Blimey! Witnesses on t' shore pointed out t' landin' spot in t' bay, me bucko, notin' t' parachute popped out about 20 feet above t' water. Aye aye! Avast! Tea-Bird floated nicely, me hearties, ya bilge rat, with plenty o' air trapped in t' hull and cone. Avast, me proud beauty! I watched it drift out o' sight downwind as it bobbed toward t' opposite shore. Begad! Got in me car and drove t' where it seemed t' be heading. Avast! Blimey! No sign o' Tea-Bird. Begad! Avast, me proud beauty! Did it sink? Then I noticed a small crowd gathered near t' Hilton Hotel beach. Well, blow me down! I ran over there, and sure enough, Tea-Bird beached with its chute like a big, matey, orange jellyfish! What's more, me hearties, t' Perfectflite MicroAlt be beepin' out "peeppeeppeeppeep..." t' 486' (height before it cocked t' horizontal)! I was lucky somebody didn't call Homeland Security! Amazingly, when I opened t' altimeter pod, out came a flood o' water, followed by a very wet altimeter, arrr, still chirping. These things are amazing! I pulled t' battery, shiver me timbers, ya bilge rat, shiver me timbers, rinsed MicroAlt with some bottled water, and it is still works great today! No More F50s. Blimey! T' maximum rated power for Tea-Bird be t' F20-F21-F23-F24-F25 series. I have since flown it on E30-4 motors, me hearties, and that is a great combination, me hearties, ya bilge rat, too; gives about 600', very wind-resistant.

Summary:

PRO: Cheap and fast t' build from free parts (well, matey, arrr, you do need t' buy t' cone, arrr, t' 2.6 LOC cone can be used). Power limited t' 29mm F20-F25, me hearties, ya bilge rat, and 24mm motor tube can be used too, me hearties, although F21s are nay too available now. Aye aye! Ahoy! Very wind resistant, shiver me timbers, and o' course, matey, W-A-T-E-R-P-R-O-O-F!
CON: Risk o' crackin' t' plastic tubefins if flown off hard desert playa or t' like. Blimey! I do have t' keep remindin' myself t' store Tea-Bird in a paper bag at t' field t' minimize sunlight damage.

scratch_tea-bird_bretherinOther:
I have enjoyed Tea-Bird so much that I have built a 4"x25" version for 38mm motors up t' I287SS (which flies superbly), ya bilge rat, arrr, and a monster 5.5"x36" version for 54mm motors up t' K445 (to fly at June 2008 ROCStock). Avast, arrr, me proud beauty! I am usin' them t' compare performance o' large, me hearties, "stubby" 6-tube vs. Ahoy! 7-tube tubefin designs; some surprisin' results so far, ya bilge rat, contruction articles will eventually be submitted t' EMRR. Begad! These will wrap up me 5 year tubefin research project (mostly published recently in SPORT ROCKETRY and ROCKETS).

Other Reviews
  • Scratch Tea-Bird By Jewel B. Butler Jr. (September 27, 2009)

    Brief: This rocket is a replic of the great rocketeer Larry Brand designed called the Tea Bird. Got the idea off the EMRR web site. The rocket is a tube-fin stubby that flies really nice and is relatively cheap to build. I started with three container that my Sugar-Free KoolAid comes in, a Bt-80 nose cone fits perfectly as Mr Brand stated in the Tea Bird article. Got the balsa nose cone from ...

Comments:

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Rich DeAngelis (December 3, 2011)

Great story of the flight!

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Steve Lindeman (November 24, 2012)

Being a tea toddler my self this really caught my attention. H-m-m-m-m-m-m. Crystal Light containers you say. I'll never see them the same again.

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