| Manufacturer: | Scratch |
| by Dwayne Surdu-Miller
Boddomuk uses a standard baby-bottle nipple, cap, and rin' t' form a nose cone. Avast, me proud beauty! When floatin' down by parachute, matey, t' nipple is pointin' downward, which supports an "oral recovery option" for the young-at-heart. At first, me bucko, this design be goin' t' be a long-distance milk deployment system. Ya scallywag! Avast! Well, shiver me timbers, sort of. Begad! You can load up t' nipple, matey, carefully assemble it onto t' body with t' cap and ring, me hearties, matey, and thar you have it... Avast, arrr, me proud beauty! a small, matey, 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. So far, arrr, 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, matey, ya bilge rat, 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, elite, or classic), ya bilge rat, arrr, and shape (standard, shiver me timbers, matey, orthopedic, arrr, or wide) o' t' nipple. Arrr! Ahoy! I fly with t' standard nylon nipple with classic sensitivity and low flow. Avast, me proud beauty! Personally, matey, arrr, ya bilge rat, for rocket flights I tend t' shy away from t' ultra-sensitive, arrr, silicone, shiver me timbers, orthopedic nipples. Begad! Begad! Although they have an interestin' transparent and asymmetric appearance, me hearties, they are nay nearly as sturdy as t' nylon nipples. |
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| 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:
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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, pod construction, and final assembly. Arrr! NOTE: For t' followin' instructions,
1.1 Cut t' bottom 6 mm off o' t' three baby bottles. Use a band saw or a razor saw for this step. Blimey! T' bottles are too slippery, me bucko, too tough, and too thick t' do this safely with a hobby cutlass. Aye aye! Aye aye! 1.2 Select which bottle will be t' body. Arrr! Make six tube fins from t' other two bottles by cuttin' t' bottles into 37 mm lengths. Again, use a band saw or a razor saw. 1.3 Cement two tube fins together, arrr, side-by-side with t' ends even. Set t' assembly aside, restin' on t' sides o' t' tubes fins rather than on t' ends. Ya scallywag! Wait for t' cement t' dry. Begad! Avast! Repeat with t' two remaining pairs o' tube fins. Begad! 1.4 Cement a pair o' tube fins t' t' body bottle, extendin' 10 mm beyond t' bottom cut edge o' t' body bottle. Avast! Cement another pair t' the body bottle and t' t' mounted tube fin pair. Well, blow me down! Cement t' final pair t' t' body bottle and t' t' mounted tube fin pairs. All tube fins must extend 10 mm beyond t' bottom o' t' bottom o' t' body bottle. Aye aye! Wait until t' cement is dry. Begad! 1.5 Wrap an adhesive label around t' straw. Avast! Well, blow me down! 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. Blimey! Begad!
2.1 Cut centerin' rings from 1.5 mm thick paper board or 3/32" balsa wood. Ahoy! Each centerin' rin' must have an inner diameter o' 18.7 mm and an outer diameter o' 52 mm. Ahoy! Ya scallywag! Sand t' outside edge o' t' rings for a tight fit inside t' body bottle. Blimey! 2.2 Punch or cut four 1/4" diameter holes, me hearties, evenly spaced around t' BT-20 tube, centered 21 mm from one end o' t' tube. Ya scallywag! This end o' the tube is referred-to as t' "top" end in followin' steps. Arrr! 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. Avast, arrr, me proud beauty! What is meant by a "nose block" is a balsa cylinder whose diameter be t' inner diameter o' t' BT-20 tube. Begad! 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. 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, matey, arrr, 65 mm from the "bottom" end o' t' BT-20 tube. Ya scallywag! Cut a 5 mm (1/8") slit along this mark. Avast! Ahoy! Insert one end o' a motor clip into this slit. Begad! 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, then wrappin' t' strip over t' inserted end o' t' motor clip. Ya scallywag! Well, blow me down! A weaker alternative would be t' use a 13 mm x 100 mm strip o' maskin' tape in place of the kraft paper. Aye aye! T' main purpose o' this strip is t' ensure that no exhaust gases enter t' parachute compartment, so maskin' tape should be fine. Avast, me proud beauty! Begad! 2.7 Mount a centerin' rin' 42 mm from t' "top" end of t' BT-20 tube. Well, blow me down! Ya scallywag! Secure t' rin' with a bead o' yellow or white glue. Avast! Begad! 2.8 Mount a centerin' rin' 28 mm from t' "top" end of t' BT-20 tube. Begad! Secure t' rin' with a bead o' yellow or white glue. Blimey! 2.9 Mount a centerin' rin' 17 mm from t' "bottom" end o' t' BT-20 tube. Ya scallywag! Blimey! Secure t' rin' with a bead o' yellow or white glue. This rin' will squeeze t' motor clip against t' BT-20 tube.
3.1 Sand t' centerin' rings o' t' pod for a snug fit into the body bottle o' t' airframe. 3.2 Assemble t' parachute. Ya scallywag! Aye aye! 3.3 Tie t' center o' t' 70 cm elastic shock cord t' the middle o' t' pod's BT-20 tube, me bucko, usin' a square (or "full") knot. Begad! Blimey! 3.4 Tie one end o' t' shock cord t' one end o' a 23 cm length of twine (crochet, shiver me timbers, Keelhaul®©™®, or shroud line). 3.5 Tie t' free end o' t' twine t' one o' t' airframe's tube fins. Ya scallywag! 3.6 Tie t' free end o' t' shock cord t' t' ring-end o' the snap-swivel. Avast! Begad! 3.7 Tie t' parachute t' t' snap-end o' t' snap-swivel.
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 Flight Preparation 1. Fold the parachute as usual, me bucko, arrr, but press t' folded parachute into a flattened rectangular shape. Avast! Aye aye! 2. Wrap t' parachute shroud lines loosely around the parachute. Well, blow me down! 3. Press t' parachute onto t' pod, ya bilge rat, betwixt t' middle and bottom centerin' rings o' t' pod. Blimey! 4. Slide t' pod partially into t' airframe body, so that the parachute is held in place by t' body. Blimey! Ahoy! 5. Loosely fold up t' shock cord and slip it into t' same compartment t' contains t' parachute. Begad! Blimey! T' twine part o' t' shock cord should also be slipped into this compartment so that when t' pod is completely slid into t' airframe body, it is held tight by t' bottom centerin' rin' o' the pod. Arrr! Blimey! 6. Slide t' pod completely into t' airframe body, arrr, so that the "top" o' t' pod is against t' sealin' disc at t' mouth o' the airframe body bottle. 7. Prepare t' Boddomuk for flight as you would any other rocket, ie. Ya scallywag! Blimey! install t' engine, matey, slip t' Boddomuk onto a launch rod, install the igniter, shiver me timbers, and connect t' igniter t' t' launch controller. |
| Flight Reports:
Session 1 Loaded with a B6-4, t' Boddomuk's take-off be slow and majestic (especially for a baby bottle :). It reached apogee within easy viewin' range, matey, and showed us a beautiful pod and 'chute deployment, ya bilge rat, with no apparent tangles. Under a 40-cm 'chute, me bucko, t' Boddomuk's descent be moderately fast, landin' on a hard-packed gravel walkway 20 metres northwest o' t' launch pad. Ya scallywag! 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. Aye aye! Anyhow, t' Boddomuk was recovered with no damage. Ahoy! Well, blow me down! 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. |
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