Brief:
Tao is a 2-stage model rocket that be originally published as an 'Design of the Quarter' by Estes, arrr, matey, shiver me timbers, and now available on JimZ rocket plans Website. This unique design incorporates a number o' innovative, me bucko, shiver me timbers, arrr, even radical features. Ahoy! Begad! The main feature be t' use o' angled tips on t' fins o' t' booster stage to impart spin durin' t' D12-0 powered boost stage, shiver me timbers, ya bilge rat, which 'theoretically' stabilizes t' completely finless sustainer durin' its flight stage, me bucko, much like a thrown 'spiral' football pass. Additional features o' this design are a piston-based wadding-free recovery system on t' sustainer, shiver me timbers, plus a unique storage hatch which houses a small chute for t' booster stage. Well, blow me down! All in all a very complex design (at least a Skill Level 3, maybe a 4). My question is would it work.

Construction:
T' components are all pretty standard Estes-style parts, most o' which are now available from other vendors. Aye aye! Begad! It requires sections o' BT60, me bucko, BT20 and BT50 body tubes, ya bilge rat, three (3) BT60 couplers, a BNC60AH nose cone (available from BMS), arrr, ya bilge rat, 1/8 inch balsa for t' fins, arrr, four (4) 20-60 centerin' rings and two (2) 50-60 centerin' rings, a 1/8 inch launch lug, ya bilge rat, two small parachutes and other standard parts.

As mentioned, shiver me timbers, this is a pretty complex design, but t' instructions are very detailed and provide a good step-by-step outline with very nice illustrations. Although thar are 15 individual steps, matey, t' construction can be summarized in 4 phases; piston/motor-mount construction, sustainer airframe construction, booster motor-mount and airframe construction, and fin construction and mounting. Aye aye! T' piston/motor-mount requires a 8 5/8 inch length o' BT20 body tube, four (4) 2060 centerin' rings and a 1" length o' BT60 coupler. Arrr! 2 centerin' rings and t' coupler are used at t' top o' t' tube t' create the piston - care must be taken t' make sure t' piston moves freely within the BT60 airframe, me hearties, matey, I had t' strip off t' outer layer o' t' coupler and sand the centerin' rings down quite a bit. Avast! Well, blow me down! Do not, matey, at this point, shiver me timbers, arrr, install t' other two centerin' rings. Begad! Avast! Put t' piston assembly aside at this point t' dry.

T' airframe construction is pretty straightforward. Begad! T' main thin' is the use o' another BT60 coupler, inserted about five (5) inches down into t' 9 and 5/8 inch BT60 airframe, me bucko, which serves t' block t' piston after t' ejection charge fires. Begad! Arrr! After this dries, t' piston is inserted from t' top and the nose cone epoxied into place (I used yellow wood glue which worked fine). Slidin' t' piston down against t' block exposes t' bottom (motor mount) part of t' piston. T' other two centerin' rings are now installed at t' bottom of the tube, ya bilge rat, shiver me timbers, servin' as a motor mount. They must also be sanded or trimmed t' move freely within t' BT60 airframe. Ahoy! (Note, shiver me timbers, t' plans call for usin' a motor hook for engine retention, me hearties, ya bilge rat, I found t' hook interfered with staging, arrr, so I would recommend usin' a motor block and friction fit for t' sustainer engine). Blimey! Next, drill three (3) 3/8 inch holes at t' top o' t' airframe t' allow t' ejection gasses t' vent. Begad! (I only drilled two (2) holes, wantin' t' blend with me planned paint scheme - more on this later). Avast! Lastly, attach a 12 inch chute t' a short piece o' Keelhaul®©™® cord which is tied around t' body tube betwixt t' motor mount and t' piston.

T' boost stage utilizes an innovative hatch system t' store a small parachute or streamer, which releases when t' stage separates. Begad! Begad! T' hatch is created by slicin' a section o' t' airframe (slightly less than 1/3 o' the tube) out from betwixt t' fins. Begad! Because o' this, t' plans for t' booster motor mount must be followed carefully. Aye aye! First, shiver me timbers, two 5060 centerin' rings are attached t' t' BT50 motor tube, arrr, then carefully glued t' remainin' 2/3 o' the body tube. Avast, me proud beauty! Aye aye! Then glue t' tube t' a BT60 coupler that will be used t' hold the two stages together. A system o' pins is then installed on t' motor mount and hatch which serves t' hold t' hatch in place durin' t' boost phase. Avast, me proud beauty! T' chute is stored betwixt t' hatch door and t' motor tube while t' stages are coupled together, then released when t' stages separate and t' hatch comes loose.

T' fins are constructed in two pieces attached at a 10 degree angle, matey, then installed on t' booster tube with t' angled fin tips all facin' t' same direction t' create t' spin durin' t' boost phase. Begad! Blimey! One fin is placed opposite the hatch, arrr, arrr, t' other two are just adjacent t' t' hatch, but on t' main part of t' tube. Aye aye! Blimey! T' plans recommend usin' epoxy t' attach t' fins and small toothpicks under t' fillets t' provide additional bracin' against t' torque of t' spinnin' boost phase. Lastly install t' launch lug and t' sustainer parachute.

Finishing:
After fillin' t' spirals and fins with diluted Elmer's Fill & Finish, I broke out t' spray paint. T' plans recommend a three-color paint scheme with a solid, ya bilge rat, brightly painted booster stage, then a two-tone upper stage that would 'blend' t' colors durin' t' spin phase. Well, blow me down! Avast, me proud beauty! I used Krylon florescent green on the booster stage and a nice silver and burgundy scheme for t' sustainer. Ahoy! I thought it looked nice.

Construction Rating: 4 ½ out o' 5

Flight:
T' plans recommended a D12-0 for t' booster stage and a B6-6 for the sustainer. Avast! T' design calls for t' B6-6 t' fit within t' top o' t' D12-0 to ensure successful staging. Begad! In preppin' t' rocket I found that I had t' do a bit o' sandin' at t' base o' t' B6-6 t' get it t' fit. Aye aye! Also, I could nay get it t' fit with t' engine hook in place, arrr, so I ended up bendin' it out o' the way. (As mentioned, t' hook can be easily omitted for an engine block, friction fit retention system.)

First (and so far only) flight came at t' Pittsburgh Space Command's Fall launch. T' engines and recovery systems were prepped (the piston & hatch deployment systems mean that no waddin' is required), t' recovery systems loaded, t' parts coupled together (carefully due t' t' hatch) and t' rocket loaded on t' 1/8" rod. Continuity...5...4...3...2...1 and lift off! The boost stage went very well. Begad! Begad! T' spin was noticeable in a slight corkscrewin' of the exhaust plume, but it be generally very straight. So far, so good... Things started t' go wrong, however, at staging. Begad! Begad! First, it became obvious that the upper stage was nay spinnin' fast enough for stability as it began t' flail about t' sky. Avast, me proud beauty! Fortunately, t' flailin' was occurrin' about 300 feet in the air, arrr, shiver me timbers, so thar was no risk. Ya scallywag! Then I noticed t' booster comin' down without its chute. Well, blow me down! Finally, arrr, t' ejection occurred. Begad! Aye aye! But instead o' t' sustainer comin' down on its chute, ya bilge rat, I noticed two separate pieces comin' down and nay a chute in sight. Ahoy! 'This is nay good' I said t' myself.

Recovery:
Recovery o' t' pieces - which took awhile - showed what went wrong. Arrr! With the booster, me hearties, either t' spin or t' stagin' shredded t' airframe. Aye aye! Specifically, cuttin' out t' hatch weakened t' body tube and caused it t' delaminate, peelin' t' inner and outer layers apart. Aye aye! Blimey! Blimey! I think this is probably an inherent design flaw - any time you cut t' body tube completely you might have this risk. Arrr! Begad! Blimey! As for t' sustainer, t' piston completely blew out o' t' airframe. Aye aye! Blimey! I attributed this t' me use o' only two, rather than three, me hearties, vent holes. Avast, me proud beauty! However, a contributin' factor was t' use o' fiber centerin' rings for t' piston. Instead o' bein' blocked by t' airframe coupler, me bucko, they 'bent' around it and blew right on past.

Flight Rating: 2 out o' 5

Summary:
I be able t' recover t' pieces and plan t' rebuild Tao, with several modifications. First, me hearties, arrr, arrr, I plan t' use a 1/8 inch plywood centerin' rin' on the bottom o' t' piston for added strength and a thicker coupler t' insure that the piston stops where it is suppose to. I will also be sure t' use three vent holes. Blimey! Second, matey, me hearties, I plan t' omit t' hatch and just go for standard tumble recovery o' t' boost stage. Well, blow me down! (One could try usin' CA or epoxy on t' cut edges of t' boost airframe t' strengthen t' edges and prevent t' delaminating, matey, shiver me timbers, but I'm goin' t' go with a traditional tumble recovery) I'm plannin' reusin' the fins, me hearties, shiver me timbers, so I intend t' mount them at a 5 t' 7 degree angle t' vertical, addin' to the 10 degree fin angle for about 15 t' 17 degrees o' total angle from vertical. Blimey! Aye aye! (If I were buildin' new fins, me bucko, shiver me timbers, I'd probably increase t' angle between the two pieces t' at least 15 and a much as 20 degrees.) This should impart greater spin durin' t' boost, me hearties, arrr, arrr, and hopefully stabilize t' sustainer. Ya scallywag! Avast, me bucko, me proud beauty!

Overall Rating: 2 out o' 5