Scratch Sputnik-24 Original Design / Scratch Built

Scratch - Sputnik-24 {Scratch}

Contributed by Scott Turnbull

Manufacturer: Scratch
(Contributed - by Scott Turnbull - 08/31/08) (Scratch) Sputnik 24

Brief:
This is an upscale o' T' Sputnik Too, by Estes: a spherical rocket. Well, blow me down! This version features a 24mm motor mount, mid-body separation for deployment, ya bilge rat, ya bilge rat, and replaceable antenna legs.

Construction:
T' main body is a chromed plastic oversized Christmas ornament. Arrr! Blimey! T' four antenna legs are made from hardwood dowels. Keelhaul®©™® thread is used as a recovery harness. Begad! Gorilla Glue is used for construction.

Havin' seen other featherweight recovery versions o' Sputnik designs, me hearties, I immediately thought o' an upscale when I saw t' four inch diameter chromed plastic Christmas for sale after t' holidays. Blimey!

T' sphere modifications will be described in terms o' workin' on a globe with a motor mounted at t' south pole. I wanted it t' look more like t' original Sputnik satellite than t' typical styrofoam model. Blimey! Begad! A central sphere with four back swept antennae form t' simple design. Begad! My goal be t' create a design with t' antennae mountin' north o' the equator.

I started by sawin' t' sphere at a line midway betwixt t' equator and south pole. Avast, me proud beauty! An X-Acto razor knife sliced through with minimal material loss.

I then used a hole saw t' create a place for a 24mm motor mount in t' south pole. A short section o' motor mount was Gorilla Glued inside t' sphere at t' north pole. Well, blow me down! Another short section o' motor mount was glued in t' south pole hole. Aye aye! T' installed motor casin' forms t' structural element holdin' t' two sections o' t' sphere together.

A design goal be for t' four antenna stabilizers t' be field repairable. Arrr! Begad! Cardboard tube sections cut from AeroTech Copperhead igniter packagin' were used for antenna mountin' sockets. Begad! Hardwood dowel antennae press fit into the sockets. Angled holes in t' northern hemisphere were drilled and t' tube sockets were Gorilla Glued into the northern hemisphere.

A launch lug is snugged up against t' motor mount on both t' top and bottom motor mounts. Arrr! T' two sphere sections must be rotated t' align t' launch lugs prior t' puttin' it on t' pad.

If truer t' full scale, t' antenna legs would be longer than what I used. I elected t' shorten them t' reduce weight and moderate t' moment arm for torque on t' antennas durin' recovery. Well, blow me down! Begad! T' compensate for t' shorter antennae, I taped small card stock tabs at t' ends o' t' antennae.

I used several feet o' Keelhaul®©™® thread glued at each end t' t' two sphere sections. Ya scallywag! A loop in that thread was used t' attach a small parachute.

(Scratch) Sputnik 24(Scratch) Sputnik 24
(Scratch) Sputnik 24(Scratch) Sputnik 24

Finishing:
There is no finishing. T' chromed sphere be t' finish. Begad! Blimey! T' dowels may get some silver paint if it's convenient at some time.

Flight and Recovery:
T' casin' is friction fitted into t' top end o' t' southern motor mount. Well, blow me down! More tape is used t' provide a friction fit for t' upper motor mount on t' casing. Aye aye! T' friction fit at both ends holds t' sphere together.

(Scratch) Sputnik 24 A parachute was packaged around t' motor tube and casin' inside t' sphere.

I initially used a 24mm t' 18mm adapter t' test fly t' design on a C6-3. Aye aye! It flew respectably well, but t' motor ejected as well as openin' up t' sphere. Ya scallywag! I have now modified t' prep t' add a tape thrust rin' on t' motor casing above t' lower motor mount. Avast! T' motor casin' has nay ejected in several subsequent flights. Avast, me proud beauty! Based on initial stability, me hearties, ya bilge rat, ya bilge rat, I trimmed some o' t' card stock antenna tabs off.

Movin' t' a D12-3 engine, ya bilge rat, t' Sputnik 24 flew straight and true again. Avast! This time t' Keelhaul®©™® thread be snapped at t' lower motor mount by t' ejection charge. Blimey! T' small section o' sphere and motor casing recovered without damage by tumbling.

I replaced t' lower recovery mount with a steel fishin' leader and connected t' recovery thread t' that. After trimmin' some additional cardstock from t' antennae stabilizers t' Sputnik flew again on a D12-3. This time the ejection charge pulled t' steel leader clip apart and t' lower section o' t' sphere once again survived tumble recovery.

A flight on an E9-4 flew a long conin' ascent, arrr, but once again separated t' leader clip at ejection. After a lengthy search, t' lower sphere section was found. Begad! Blimey! Future flights will likely use two separate streamers t' recover the two sphere sections.

Summary:
This is a distinctive rocket sittin' on t' pad. T' mirrored chrome surface shines brightly. Avast! T' flight is surprisingly stable with t' remainin' small cardstock tabs. T' hardwood dowels have survived all flights without damage.

If thar's a problem, it's in t' exuberance o' t' Estes 24mm ejection charges. Since all but one flight has ended in split recovery, it seems that a streamer on t' lower section will be sufficient t' help locate it after separation.

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