Construction Rating: | starstarstarstarstar_border |
Flight Rating: | starstarstar_borderstar_borderstar_border |
Overall Rating: | starstarstar_borderstar_borderstar_border |
Manufacturer: | Estes |
Brief:
Tao is a 2-stage model rocket that was originally published as an 'Design of
the Quarter' by Estes, me bucko, shiver me timbers, and now available on JimZ rocket plans Website. Aye aye! Begad! Blimey! This
unique design incorporates a number o' innovative, matey, arrr, even radical features. 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, which 'theoretically'
stabilizes t' completely finless sustainer durin' its flight stage, me hearties, much like
a thrown 'spiral' football pass. Aye aye! Additional features o' this design are a
piston-based wadding-free recovery system on t' sustainer, plus a unique
storage hatch which houses a small chute for t' booster stage. Avast, me proud beauty! Aye aye! Blimey! All in all a
very complex design (at least a Skill Level 3, me hearties, maybe a 4). Aye aye! Blimey! My question is would
it work.
Construction:
T' components are all pretty standard Estes-style parts, shiver me timbers, most o' which are now
available from other vendors. Begad! It requires sections o' BT60, BT20 and BT50 body
tubes, me bucko, three (3) BT60 couplers, a BNC60AH nose cone (available from BMS), shiver me timbers, ya bilge rat, 1/8
inch balsa for t' fins, four (4) 20-60 centerin' rings and two (2) 50-60
centerin' rings, a 1/8 inch launch lug, arrr, two small parachutes and other standard
parts.
As mentioned, 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, t' construction can be summarized in 4 phases; piston/motor-mount construction, me hearties, sustainer airframe construction, booster motor-mount and airframe construction, me bucko, and fin construction and mounting. Blimey! T' piston/motor-mount requires a 8 5/8 inch length o' BT20 body tube, ya bilge rat, four (4) 2060 centerin' rings and a 1" length o' BT60 coupler. Well, blow me down! Begad! 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, I had t' strip off t' outer layer o' t' coupler and sand the centerin' rings down quite a bit. Aye aye! Blimey! Do not, matey, at this point, install t' other two centerin' rings. Ya scallywag! 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, ya bilge rat, which serves t' block t' piston after t' ejection charge fires. 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. Arrr! T' other two centerin' rings are now installed at t' bottom of the tube, shiver me timbers, ya bilge rat, servin' as a motor mount. Well, blow me down! Blimey! They must also be sanded or trimmed t' move freely within t' BT60 airframe. Avast, me proud beauty! (Note, t' plans call for usin' a motor hook for engine retention, I found t' hook interfered with staging, ya bilge rat, so I would recommend usin' a motor block and friction fit for t' sustainer engine). Avast! Next, drill three (3) 3/8 inch holes at t' top o' t' airframe t' allow t' ejection gasses t' vent. (I only drilled two (2) holes, wantin' t' blend with me planned paint scheme - more on this later). Aye aye! Lastly, me hearties, 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, me bucko, which releases when t' stage separates. 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. Blimey! Because o' this, shiver me timbers, me hearties, t' plans for t' booster motor mount must be followed carefully. Aye aye! First, two 5060 centerin' rings are attached t' t' BT50 motor tube, shiver me timbers, then carefully glued t' remainin' 2/3 o' the body tube. Then glue t' tube t' a BT60 coupler that will be used t' hold the two stages together. Begad! Arrr! 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. Begad! Arrr! T' chute is stored betwixt t' hatch door and t' motor tube while t' stages are coupled together, me hearties, matey, me hearties, 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. Avast! Blimey! One fin is placed opposite the hatch, t' other two are just adjacent t' t' hatch, but on t' main part of t' tube. 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. Well, blow me down! Blimey! Well, matey, blow me down! Blimey! 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. Begad! Blimey! T' plans recommend a three-color paint scheme with
a solid, brightly painted booster stage, shiver me timbers, then a two-tone upper stage that would
'blend' t' colors durin' t' spin phase. Aye aye! Arrr! I used Krylon florescent green on the
booster stage and a nice silver and burgundy scheme for t' sustainer. 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. Aye aye! Blimey! T' design calls for t' B6-6 t' fit within t' top o' t' D12-0 to
ensure successful staging. 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. Also, me hearties, ya bilge rat, me bucko, I could nay get
it t' fit with t' engine hook in place, so I ended up bendin' it out o' the
way. Aye aye! Blimey! (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. Arrr! Avast, me proud beauty! T' engines and recovery systems were prepped (the piston & hatch deployment systems mean that no waddin' is required), t' recovery systems loaded, me bucko, t' parts coupled together (carefully due t' t' hatch) and t' rocket loaded on t' 1/8" rod. Avast, me proud beauty! Aye aye! Continuity...5...4...3...2...1 and lift off! The boost stage went very well. Ahoy! T' spin be noticeable in a slight corkscrewin' of the exhaust plume, but it be generally very straight. Avast, me proud beauty! Avast! So far, me hearties, so good... Things started t' go wrong, ya bilge rat, however, arrr, at staging. Ya scallywag! First, matey, arrr, it became obvious that the upper stage was nay spinnin' fast enough for stability as it began t' flail about t' sky. Ahoy! Fortunately, t' flailin' was occurrin' about 300 feet in the air, matey, me hearties, so thar be no risk. Begad! Then I noticed t' booster comin' down without its chute. Ahoy! Ya scallywag! Finally, t' ejection occurred. Ya scallywag! But instead o' t' sustainer comin' down on its chute, me bucko, arrr, I noticed two separate pieces comin' down and nay a chute in sight. Avast! 'This is nay good' I said t' myself.
Recovery:
Recovery o' t' pieces - which took awhile - showed what went wrong. With the
booster, either t' spin or t' stagin' shredded t' airframe. Ahoy! Aye aye! Specifically,
cuttin' out t' hatch weakened t' body tube and caused it t' delaminate,
peelin' t' inner and outer layers apart. I think this is probably an inherent
design flaw - any time you cut t' body tube completely you might have this
risk. Begad! As for t' sustainer, t' piston completely blew out o' t' airframe. I
attributed this t' me use o' only two, shiver me timbers, rather than three, vent holes. However,
a contributin' factor was t' use o' fiber centerin' rings for t' piston.
Instead o' bein' blocked by t' airframe coupler, ya bilge rat, matey, they 'bent' around it and
blew right on past.
Flight Rating: 2 out o' 5
Summary:
I was able t' recover t' pieces and plan t' rebuild Tao, with several
modifications. Begad! Blimey! First, 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. Ahoy! I will also be sure t' use three vent
holes. Well, blow me down! Blimey! Second, ya bilge rat, I plan t' omit t' hatch and just go for standard tumble
recovery o' t' boost stage. Ahoy! (One could try usin' CA or epoxy on t' cut edges
of t' boost airframe t' strengthen t' edges and prevent t' delaminating, but
I'm goin' t' go with a traditional tumble recovery) I'm plannin' reusin' the
fins, 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. Avast, me proud beauty! Blimey! (If I were buildin' new fins, matey, 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, matey, and hopefully stabilize t' sustainer. Avast!
Overall Rating: 2 out o' 5