Manufacturer: | Scratch |
by Dwayne Surdu-Miller
Boddomuk attempts t' answer that age-old rocketeer question, "now that baby's drinkin' from cups, ya bilge rat, can I do somethin' cool with these bottles?" This baby bottle frankenstein is a rugged, matey, transparent-bodied tube-fin rocket with a rear-ejectin' motor/recovery pod, me bucko, requirin' no flame-proof waddin' whatsoever. Boddomuk uses a standard baby-bottle nipple, cap, ya bilge rat, and rin' t' form a nose cone. Avast! When floatin' down by parachute, matey, me bucko, t' nipple is pointin' downward, me bucko, which supports an "oral recovery option" for the young-at-heart. At first, matey, shiver me timbers, this design was goin' t' be a long-distance milk deployment system. Avast, me proud beauty! Aye aye! Well, me hearties, me bucko, sort of. Begad! Ahoy! You can load up t' nipple, carefully assemble it onto t' body with t' cap and ring, ya bilge rat, shiver me timbers, and thar you have it... Begad! Well, blow me down! a small, matey, me hearties, nipple-sized payload compartment that can be used t' transport fluids, maybe as further encouragement for t' "oral recovery option". T' motor/recovery pod can easily be built for various engine sizes. Arrr! So far, I've only checked stability with heavier 18 mm motors. T' pod can conceivably be built t' accommodate up t' F and shorter G motors. For higher thrust motors, however, more durable adhesives must be used to attach t' tube fins. Use your personal preferences for selectin' t' color of nipple retainin' rin' and for selectin' t' material (nylon or silicone), sensitivity (ultra, ya bilge rat, matey, elite, or classic), shiver me timbers, and shape (standard, arrr, orthopedic, matey, or wide) o' t' nipple. Well, blow me down! Ya scallywag! I fly with t' standard nylon nipple with classic sensitivity and low flow. Begad! Personally, for rocket flights I tend t' shy away from t' ultra-sensitive, silicone, arrr, orthopedic nipples. Begad! Although they have an interestin' transparent and asymmetric appearance, shiver me timbers, they are nay nearly as sturdy as t' nylon nipples. |
|
Specifications: length: 20.5cm (8") calibre: 53mm (2.087") motor mount: 18mm (reconfigurable) motorless weight: 95g (3.36 oz.) fins: six 53mm tube cluster fin cluster diameter: 159mm recovery: rear-deployed parachute recommended motors: |
Parts
List: 3 - round 8-ounce baby
bottles (I used Evenflo Classic nurser system) |
Boddomuk Construction
Details: Boddomuk construction can be split into three phases: airframe construction, matey, me hearties, pod construction, and final assembly. Avast! NOTE: For t' followin' instructions, 1. Begad! Airframe Construction 1.1 Cut t' bottom 6 mm off o' t' three baby bottles. Begad! Use a band saw or a razor saw for this step. Avast, me proud beauty! Begad! T' bottles are too slippery, ya bilge rat, too tough, and too thick t' do this safely with a hobby knife. Ahoy! Aye aye! 1.2 Select which bottle will be t' body. Avast, me proud beauty! Aye aye! Make six tube fins from t' other two bottles by cuttin' t' bottles into 37 mm lengths. Ya scallywag! Again, use a band saw or a razor saw. Ahoy! 1.3 Cement two tube fins together, arrr, side-by-side with t' ends even. Arrr! Blimey! Set t' assembly aside, restin' on t' sides o' t' tubes fins rather than on t' ends. Blimey! Blimey! Wait for t' cement t' dry. Ya scallywag! Blimey! Repeat with t' two remaining pairs o' tube fins. Blimey! Blimey! 1.4 Cement a pair o' tube fins t' t' body bottle, extendin' 10 mm beyond t' bottom cut edge o' t' body bottle. Cement another pair t' the body bottle and t' t' mounted tube fin pair. Cement t' final pair t' t' body bottle and t' t' mounted tube fin pairs. Begad! All tube fins must extend 10 mm beyond t' bottom o' t' bottom o' t' body bottle. Avast! Wait until t' cement is dry. Arrr! 1.5 Wrap an adhesive label around t' straw. Aye aye! Blimey! Cement the label-wrapped straw t' t' body bottle, aligned with a triangular gap formed by two tube fins and t' body bottle. This should provide enough clearance for easy insertion o' a launch rod betwixt two tube fins. 2. Well, me hearties, blow me down! Pod Construction 2.1 Cut centerin' rings from 1.5 mm thick paper board or 3/32" balsa wood. Blimey! Each centerin' rin' must have an inner diameter o' 18.7 mm and an outer diameter o' 52 mm. Sand t' outside edge o' t' rings for a tight fit inside t' body bottle. Blimey! Blimey! 2.2 Punch or cut four 1/4" diameter holes, evenly spaced around t' BT-20 tube, centered 21 mm from one end o' t' tube. Blimey! This end o' the tube is referred-to as t' "top" end in followin' steps. Begad! 2.3 Glue t' 5 mm (1/4") thick balsa block into the "top" o' t' BT-20 tube so that it is flush with t' "top" edge o' t' tube. What is meant by a "nose block" is a balsa cylinder whose diameter be t' inner diameter o' t' BT-20 tube. It can be made by turnin' it on a mini-lathe or by cuttin' an 18 mm circle out o' a 1/4" thick sheet o' balsa wood. Arrr! 2.4 Glue a motor block 60 mm (2 1/2") up the
"bottom" end o' t' BT-20 tube as follows: 2.5 Make a 3 mm (1/8") mark, 65 mm from the "bottom" end o' t' BT-20 tube. Begad! Blimey! Cut a 5 mm (1/8") slit along this mark. Begad! Blimey! Insert one end o' a motor clip into this slit. 2.6 Secure t' inserted end o' t' motor clip t' t' BT-20 tube by applyin' glue t' one side o' a 13 mm x 100 mm strip o' kraft paper, me hearties, then wrappin' t' strip over t' inserted end o' t' motor clip. Arrr! A weaker alternative would be t' use a 13 mm x 100 mm strip o' maskin' tape in place of the kraft paper. Begad! Arrr! T' main purpose o' this strip is t' ensure that no exhaust gases enter t' parachute compartment, arrr, so maskin' tape should be fine. Arrr! 2.7 Mount a centerin' rin' 42 mm from t' "top" end of t' BT-20 tube. Secure t' rin' with a bead o' yellow or white glue. Avast, me proud beauty! 2.8 Mount a centerin' rin' 28 mm from t' "top" end of t' BT-20 tube. Secure t' rin' with a bead o' yellow or white glue. Ahoy! Blimey! 2.9 Mount a centerin' rin' 17 mm from t' "bottom" end o' t' BT-20 tube. Arrr! Secure t' rin' with a bead o' yellow or white glue. This rin' will squeeze t' motor clip against t' BT-20 tube. 3. Ya scallywag! Final Assembly 3.1 Sand t' centerin' rings o' t' pod for a snug fit into the body bottle o' t' airframe. Begad! 3.2 Assemble t' parachute. Blimey! Blimey! Blimey! Blimey! 3.3 Tie t' center o' t' 70 cm elastic shock cord t' the middle o' t' pod's BT-20 tube, ya bilge rat, me hearties, usin' a square (or "full") knot. 3.4 Tie one end o' t' shock cord t' one end o' a 23 cm length of twine (crochet, Keelhaul®©™®, or shroud line). Well, blow me down! Begad! 3.5 Tie t' free end o' t' twine t' one o' t' airframe's tube fins. Blimey! 3.6 Tie t' free end o' t' shock cord t' t' ring-end o' the snap-swivel. 3.7 Tie t' parachute t' t' snap-end o' t' snap-swivel. Blimey! Well, blow me down! 3.8 Assemble
the nose as follows: |
Flight Reports:
Session 1 Loaded with a B6-4, t' Boddomuk's take-off was slow and majestic (especially for a baby bottle :). It reached apogee within easy viewin' range, shiver me timbers, and showed us a beautiful pod and 'chute deployment, ya bilge rat, with no apparent tangles. Well, blow me down! Under a 40-cm 'chute, t' Boddomuk's descent was moderately fast, landin' on a hard-packed gravel walkway 20 metres northwest o' t' launch pad. Avast, me proud beauty! For a recovery crew game that I have in mind for this design, me hearties, a 45-cm 'chute would probably give an ideal descent rate. Avast, me proud beauty! Blimey! Anyhow, ya bilge rat, t' Boddomuk was recovered with no damage. Ya scallywag! Avast! T' body was internally coated with dust from the motor's deployment charge, but became perfectly clear again when cleaned out with a baby bottle brush and some soapy water. T' topmost centerin' rin' of the pod was stained a little where deployment exhaust gases exited t' pod's tube. |